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V1 David K's Extended Track Goblin #343 - 06 SS Donor
Keckster
Well-Known Member
- Keckster Well-Known Member
Short little video update on the past racing season on my YT channel today. Don't mind the SEO title and description lol. This season I drove to, participated, and drove home from 10 different racing events across 3 states in the North East.
Winter 2024 projects: (Broke the bank...)
- Fueltech FT550 ✔
- Complete custom wiring Harness ✔
- Cat V Ported head ✔
- Dyno tuned ✔
- New Wrap ✔
- Sticker Hoosier A7 ✔
- DF Subframe ✔
- Wider rear wheels and tires ✔
- Oil Accumulator ✔
Fueltech FT550, Hardwire PDM, and Custom Wiring
I did complete the custom harness for the FT550 with lots of learning and late nights and it is working great, Most of the time lol. I had a single wiring issue when at my first event a wire coming out of the tunnel rubbed through and was grounding out. I really enjoyed making the new wiring harness and would absolutely do it again if anyone wants to swap over to an aftermarket ECU.
Dyno Tuning
The first startup and tuning of the Goblin did not go very well initially. We were trying to use sequential injection and spark but the engine turns over too slowly to get a cam sync. I was looking for a way to make the engine turn over faster but did not come across aftermarket starter for a cobalt and I didn't want to modify my existing starter and possibly hurt the reliability/lifespan. Eventually we figured it out and got the car to make 307 HP and 260 ft*lbs of torque on a hub dyno. The car was tuned by BluTunesEFI down in Spring Grove, PA, Jon is a really nice guy, very understanding, and reasonably priced for his great service and commitment.
Autox Events
This year I drove in 7 different Autocross events in 5 months with the main goal of obtaining as much seat time as possible. For the first event I got caught in the rain and had a wire ground out shutting me down early. Upon fixing the wire issue I had zero day ending issues apart from an extremely sensitive pedal which I eventually remedied with a large spring.
Mid Atlantic Car Fest (Oct. 10-13, Northeast US)
The event I was most excited for this year was Mid Atlantic Car Fest (MACF) which is a spin on the drag and drive event genre. We started our weekend at Dominion Raceway in Virginia on the .4 Mile Oval track. I honestly was a little intimidated by the oval as you are in a dish surrounded by track and walls if you were to loose it. In the end the oval had a ton of grip and the only thing holding me and the goblin back was my lack of confidence.
The second event of MACF was a track day on the 2 Mile Dominion Raceway track just after we finished on the oval. This was my first track event and I was just starting to get into it when I ran into my first issue of the weekend. On the back straight of the track I found that the car just wouldn't accelerate and more past about 5k rpm in 3rd gear, This caused a lot of heat to build up behind the exhaust and I ended up melting through a shifter cable. I am convinced this issue was caused by the lack of E85 in virginia and the car is down about 70HP on 93 octane. I ended up being able to free up the melted shifter cable by cycling it and dripping oil down inside the case. I unfortunately only got one session on the track due to the broken shifter cable. The other issue that arrived at the track is a large leak when making higher G turns, I am still unsure what was leaking but when I would take a turn it would spray all over the back of my seats and on the exhaust leaving a big mess everywhere.
After the day at Dominion Raceway we stayed in a Hotel at the track then woke up and drove to Mason Dixon Dragway for our next event. I have never gone down a drag strip and actually found it to be a lot of fun with friends. When we got to the Drag strip I was still on 93 octane fuel and the best I could run was a 14.2 at about 90 mph. I honestly expected the goblin to be a lot faster but the most I know on drag racing is watching Cleetus on YouTube lol. I was searching for gas stations nearby with E85 and found one about 25 minutes away. I emptied my tank to about 2 gallons into a friends car then left to find the gas station. The car instantly was happier even before getting back to the track. My final fastest time was a 13.195s at 100MPH. Maybe the goblin could go faster but I could barely get any grip on the track so maybe the prep wasn't very good. After our private track rental at Mason Dixon, We left taking scenic roads through the Appalachians to stay in a hotel in Altoona for our next event.
Day 3 of MACF was an Autocross event at Mid State Airport with the Central Pennsylvania SCCA Region. At this event is where I ran into another big problem. I ended up overextending my drivers side axle on my second run of the day cracking my transmission case. Everyone from the MACF event jumped into action to make sure we all made it to the end. Almost everyone offered me to borrow their car to run and get parts to fix it. After about 4 hours we finally found an axle and returned to the airport to repair my goblin. Once we got back to the car we found the axle was too short, which upon further inspection was due to the upright bending from the first axle breaking. One of the guys in our group pulled out a grinder and cut a 1/5 inch spacer off his jack handle so we could get the car driving. I decided to bring the car home and park it rather than push my luck going to the final event. I jumped in my daily driver and met everyone back at our hotel for for the final event of the weekend.
Our final event of MACF was a track sprint hosted by NEPA SCCA at Pocono Raceway. I was originally just gonna attend to support the rest of the MACF group but Bob Schiffer offered me to co-drive his goblin for the event. I am forever grateful for his offer and was not ready for the power of his LSJ-t. Unfortunately the video corrupted for our runs in his goblin but it was incredibly fast at Pocono on AR1s. I ended up finishing the event in 9th out of 20 after not getting all runs for 2 of the four events.
Winter 2025 Projects:
- Fix Supercharger loop Heat Exchanger leak
- Fix Transmission leak
- Install Catch Can
- Powder coat and install replacement rear control arms
- Cleanup entire car from various leaks
- Adjust Pedal Positions
- Replace cracked windshield (optic armor or glass?)
Winter 2024 projects: (Broke the bank...)
- Fueltech FT550 ✔
- Complete custom wiring Harness ✔
- Cat V Ported head ✔
- Dyno tuned ✔
- New Wrap ✔
- Sticker Hoosier A7 ✔
- DF Subframe ✔
- Wider rear wheels and tires ✔
- Oil Accumulator ✔
Fueltech FT550, Hardwire PDM, and Custom Wiring
I did complete the custom harness for the FT550 with lots of learning and late nights and it is working great, Most of the time lol. I had a single wiring issue when at my first event a wire coming out of the tunnel rubbed through and was grounding out. I really enjoyed making the new wiring harness and would absolutely do it again if anyone wants to swap over to an aftermarket ECU.
Dyno Tuning
The first startup and tuning of the Goblin did not go very well initially. We were trying to use sequential injection and spark but the engine turns over too slowly to get a cam sync. I was looking for a way to make the engine turn over faster but did not come across aftermarket starter for a cobalt and I didn't want to modify my existing starter and possibly hurt the reliability/lifespan. Eventually we figured it out and got the car to make 307 HP and 260 ft*lbs of torque on a hub dyno. The car was tuned by BluTunesEFI down in Spring Grove, PA, Jon is a really nice guy, very understanding, and reasonably priced for his great service and commitment.
Autox Events
This year I drove in 7 different Autocross events in 5 months with the main goal of obtaining as much seat time as possible. For the first event I got caught in the rain and had a wire ground out shutting me down early. Upon fixing the wire issue I had zero day ending issues apart from an extremely sensitive pedal which I eventually remedied with a large spring.
Mid Atlantic Car Fest (Oct. 10-13, Northeast US)
The event I was most excited for this year was Mid Atlantic Car Fest (MACF) which is a spin on the drag and drive event genre. We started our weekend at Dominion Raceway in Virginia on the .4 Mile Oval track. I honestly was a little intimidated by the oval as you are in a dish surrounded by track and walls if you were to loose it. In the end the oval had a ton of grip and the only thing holding me and the goblin back was my lack of confidence.
The second event of MACF was a track day on the 2 Mile Dominion Raceway track just after we finished on the oval. This was my first track event and I was just starting to get into it when I ran into my first issue of the weekend. On the back straight of the track I found that the car just wouldn't accelerate and more past about 5k rpm in 3rd gear, This caused a lot of heat to build up behind the exhaust and I ended up melting through a shifter cable. I am convinced this issue was caused by the lack of E85 in virginia and the car is down about 70HP on 93 octane. I ended up being able to free up the melted shifter cable by cycling it and dripping oil down inside the case. I unfortunately only got one session on the track due to the broken shifter cable. The other issue that arrived at the track is a large leak when making higher G turns, I am still unsure what was leaking but when I would take a turn it would spray all over the back of my seats and on the exhaust leaving a big mess everywhere.
After the day at Dominion Raceway we stayed in a Hotel at the track then woke up and drove to Mason Dixon Dragway for our next event. I have never gone down a drag strip and actually found it to be a lot of fun with friends. When we got to the Drag strip I was still on 93 octane fuel and the best I could run was a 14.2 at about 90 mph. I honestly expected the goblin to be a lot faster but the most I know on drag racing is watching Cleetus on YouTube lol. I was searching for gas stations nearby with E85 and found one about 25 minutes away. I emptied my tank to about 2 gallons into a friends car then left to find the gas station. The car instantly was happier even before getting back to the track. My final fastest time was a 13.195s at 100MPH. Maybe the goblin could go faster but I could barely get any grip on the track so maybe the prep wasn't very good. After our private track rental at Mason Dixon, We left taking scenic roads through the Appalachians to stay in a hotel in Altoona for our next event.
Day 3 of MACF was an Autocross event at Mid State Airport with the Central Pennsylvania SCCA Region. At this event is where I ran into another big problem. I ended up overextending my drivers side axle on my second run of the day cracking my transmission case. Everyone from the MACF event jumped into action to make sure we all made it to the end. Almost everyone offered me to borrow their car to run and get parts to fix it. After about 4 hours we finally found an axle and returned to the airport to repair my goblin. Once we got back to the car we found the axle was too short, which upon further inspection was due to the upright bending from the first axle breaking. One of the guys in our group pulled out a grinder and cut a 1/5 inch spacer off his jack handle so we could get the car driving. I decided to bring the car home and park it rather than push my luck going to the final event. I jumped in my daily driver and met everyone back at our hotel for for the final event of the weekend.
Our final event of MACF was a track sprint hosted by NEPA SCCA at Pocono Raceway. I was originally just gonna attend to support the rest of the MACF group but Bob Schiffer offered me to co-drive his goblin for the event. I am forever grateful for his offer and was not ready for the power of his LSJ-t. Unfortunately the video corrupted for our runs in his goblin but it was incredibly fast at Pocono on AR1s. I ended up finishing the event in 9th out of 20 after not getting all runs for 2 of the four events.
Winter 2025 Projects:
- Fix Supercharger loop Heat Exchanger leak
- Fix Transmission leak
- Install Catch Can
- Powder coat and install replacement rear control arms
- Cleanup entire car from various leaks
- Adjust Pedal Positions
- Replace cracked windshield (optic armor or glass?)
. It is not always those dates, I can let you know when this year's event is scheduled. It is usually a thursday through sunday around the middle of october
Ross
Goblin Professor
- Ross Goblin Professor
Nice summary of your racing season. A year's worth of testing and debugging your car is well worth the effort. I know my car's handling drastically improved over my first race season. Thanks for making a video!
Rauq
Goblin Guru
- Rauq Goblin Guru
I just got around to watching your video and I have a ton of questions, but I'll start with these:
- Can you share some info on your oil accumulator, where you connected it and if you're using an electronic or manual valve or what?
- Are you still running stock cams and valve springs?
- It seems the accelerator pedal spring took out a lot of throttle touchiness, did you make any adjustments to throttle mapping or sensitivity in the FT550?
- It looks like you powered all your accessories (lights, horn, etc.) through a PDM, is that correct? Did you rewire everything or did you reuse any of your original wiring?
Keckster
Well-Known Member
- Keckster Well-Known Member
Thank you for watching it! I'd be glad to answer any questions you have the best I can!
The oil Accumulator is a Moroso 23900 3 Quart that I purchased as recommended by a few of the faster guys in the goblin community. I mounted it using large hose clamps to the chassis for MACF in october. I will probably move it somewhere else cause I'm not a huge fan of it's current mount. I use a manual valve and run it directly to the crank oil galley via the plugs on the side of the block under the intake.
Blue Circle is the galley port I used. I used an M12x1.75 to 6an fitting from racetronics.
No, I have 82lb valve springs and .5 mm oversized valves from Category V Portworx and ZZP Stage 2 supercharged cams. I honestly don't know how to read the cam numbers but here are the specs, 216/218 @ 1mm and 10.78mm/10.69mm lift, 111 LSA. If you know more about cam specs please educate me!
We did work on the throttle maps a little before adding a spring to the pedal which didn't seem to do anything but make the power feel kind of strange. I have not changed the tune since the first even of the season.
I made my own completely custom harness from scratch. I guess I can't necessarily say complete scratch cause I used an ft550 unterminated harness that I then modified to what I needed. Here is a link to the Google Sheetz that I planned the entire harness out in: Fueltech Wiring
Rauq
Goblin Guru
- Rauq Goblin Guru
I don't really think you need any ideas or help to find your fluid leak, but just to make sure this is on your list for inspection- I had a leak from the input shaft seal that you can see here.
Also looked back through your build thread and thought I'd tag @Ross to see if there were any updates on your thermostat housing project.
Also looked back through your build thread and thought I'd tag @Ross to see if there were any updates on your thermostat housing project.
Keckster
Well-Known Member
- Keckster Well-Known Member
you hit the nail on the head on the first thing on my list to check
. It is between that or some threads I stripped out on the clutch cylinder and “fixed” with JB weld. I think another problem getting fluid everywhere is the gasket on the fuel tank and blow coming from my valve cover vent.As for the heater core I was designing, I couldn’t really find a way to get it made affordably. I was tempted to try doing some plaster lost plastic casting but haven’t gotten around to it. I could dig the project back up but am a little short on money right now unfortunately.
Rauq
Goblin Guru
- Rauq Goblin Guru
I'd imagine if the throwout bearing is not firmly sealed against the inner bellhousing service then you could also get a leak around the face seal and not the input shaft seal. But I'll let you get eyes on and report back to satisfy my curiousity!
Do you have any idea what powdered metal 3d printing costs? I just have no idea if you were to upload a part like that if it'd come back at $100 per part or $1000 per part. Just curious... again!
Do you have any idea what powdered metal 3d printing costs? I just have no idea if you were to upload a part like that if it'd come back at $100 per part or $1000 per part. Just curious... again!
Keckster
Well-Known Member
- Keckster Well-Known Member
I have made a bunch of changes to hopefully improve the overall mechanical handling capabilities of my goblin. Lets start with a recap of the setup at the end of my 2025 season. I want to preface that I am not a professional in tuning or setup however, I have met many incredibly fast people and have worked with them to improve both my driving and setup.
2025 end setup
Spring Rate: 400F/550R
Damper Clicks: I honestly don't remember but 11 front 6 rear from softest keeps popping up in my mind...
I kept raising the spring rate around the car to help combat the amount of roll and oversteer the car seemed to have. I ended but getting a relatively stable car with this final setup however, it was way too stiff for anything but a perfectly smooth track.
Ride Height: LCA horizontal
DF recommended setup. I did some math and modeling of the stock setup and it leaves little room for travel before the roll center on our cars dips below ground which from my reading can cause some very unpredictable handling characteristics.
Alignment:
Caster: 5.5°
Camber: -3.2°F, -2.2°R
Toe: .15° (roughly 1/8")
Alignment seemed pretty good. I had struggled getting more rear camber due to what seemed like machining differences in the BC coilovers so I had just set it to the max that one side could do and set the other to match. I will be experimenting this year with decreasing the front end alignment after measuring the camber curve at the front end and observing the tire wear, temperatures, and pressures under racing conditions. From my roughly CAD design of our front suspension we gain about 0.4° of negative camber for every inch of wheel travel.
2026 Setup Changes
Spring Rate: 220F (2.0hz)/400R (2.6hz)
Flat Ride: 30% (47mph critical velocity)
Anti-Dive: Move front UCA mounting point up 3/4"
No Rake: 16.7 %
0.8° Rake: 21.4 % (Current Setup)
1.8° Rake 26.5 %
(Honestly not sure why I chose these angles for rake when I did my original math a while ago but I did confirm they are still correct)
This spring rate change was something I tried before to get a more mathematically ideal ride frequency however the front suspension geometry on the goblin from DF does not include any anti-dive characteristics to stop the nose from hitting the ground under hard braking. By moving the front upper control arm mounting point up by 3/4" I should now have roughly 18% anti-dive with the car setup level front to rear. I can also adjust the anti-dive percentage by adding rake to the car by raising the rear suspension or lowering the front.
Ride Heights (Measured from center of LCA mounting point on chassis to ground):
Front: 9.3" (25% roll center height w/ 20mm LCA spacer)
roughly 20° of LCA travel from full droop (Binding) to point where RC intersects the ground plane
Flipped front LCA so shock mount was on top for more travel(only 14.5° stock) and easier ARB Mounting
Rear: 8.9" (17.5% roll center height w/ 20mm LCA spacer)
roughly 14.25° of LCA travel from full droop(Binding) to point where RC intersects the ground plane
Installed bump stops on rear shocks to shorten stroke where RC intersects the ground
This winter while measuring, studying, and modeling the goblin suspension I learned that when starting with the control arms horizontal we have very little room before our roll center becomes unpredictable. I brought this up to a couple fast engineers/drivers in SCCA and they noticed in pictures how the rear MacPherson strut going past level is very undesirable and the reason when cars are lowered they often use extended ball joints to fix the RC. By increasing the ride height all around to have some downward slope to the lower control arms and installing a spacer on the bottom of the uprights I have given myself more travel while keeping the actual chassis of the goblin at a relatively similar height to stock.
Front Anti-Roll Bar/Sway Bar
3/4" x 40" straight bar
Arms with adjustment from 3.5" to 8"
I believe personally that this sway bar will be the biggest performance boost for my setup. at the stiffest setting on my ARB the front axle weight transfer distribution is roughly 60% and I have adjustability all the way down to 40%. Stock from DF setup guidelines does have roughly 40% from weight transfer however the flat ride percentage is reversed with a higher frequency up front compared to the rear.
Alignment:
Caster: 5.5° (should be the same however I did not check after flipping the LCA)
Camber: -2° F(Max attainable after flipping the LCA for some reason), -2.5° R
Toe: 1/8" In
Alignment I tried to keep similar to last year except for the inability to get the front camber back down after adding the spacers and flipping the LCA. I slotted the rear BC coilover mounts a little more to fix my low camber in the rear. I actually am planning to decrease the front camber more after this test and tune after noticing the outside edge of the tire is not being utilized unless I set the tire pressure super low which when measuring the tread temperature was too low of a pressure.
First Test on New Setup
Now I am by no means a professional, I'd even be cautious about calling myself intermediate, but the difference between any other setup I've had and this one is in my opinion night and day. The car is still extremely responsive to my input but it is not trying to snap the rear end out constantly and even when i do slide the rear end out it is infinitely easier to recover from. I've attached a video of my fastest run from the test and tune which was 6th fastest raw time for the day and only 2 seconds behind an autocross national champion in a dodge viper.
I am an engineering student with a passion for motorsport that I have found over the last few years. I know I have a lot to learn but really feel like I made some progress with this great starting point of a chassis. Feel free to ask any questions or voice any concerns. I may entertain the idea of putting together some sort of group buy for a front ARB if there seems like a decent amount of interest in it.
2025 end setup
Spring Rate: 400F/550R
Damper Clicks: I honestly don't remember but 11 front 6 rear from softest keeps popping up in my mind...
I kept raising the spring rate around the car to help combat the amount of roll and oversteer the car seemed to have. I ended but getting a relatively stable car with this final setup however, it was way too stiff for anything but a perfectly smooth track.
Ride Height: LCA horizontal
DF recommended setup. I did some math and modeling of the stock setup and it leaves little room for travel before the roll center on our cars dips below ground which from my reading can cause some very unpredictable handling characteristics.
Alignment:
Caster: 5.5°
Camber: -3.2°F, -2.2°R
Toe: .15° (roughly 1/8")
Alignment seemed pretty good. I had struggled getting more rear camber due to what seemed like machining differences in the BC coilovers so I had just set it to the max that one side could do and set the other to match. I will be experimenting this year with decreasing the front end alignment after measuring the camber curve at the front end and observing the tire wear, temperatures, and pressures under racing conditions. From my roughly CAD design of our front suspension we gain about 0.4° of negative camber for every inch of wheel travel.
2026 Setup Changes
Spring Rate: 220F (2.0hz)/400R (2.6hz)
Flat Ride: 30% (47mph critical velocity)
Anti-Dive: Move front UCA mounting point up 3/4"
No Rake: 16.7 %
0.8° Rake: 21.4 % (Current Setup)
1.8° Rake 26.5 %
(Honestly not sure why I chose these angles for rake when I did my original math a while ago but I did confirm they are still correct
)This spring rate change was something I tried before to get a more mathematically ideal ride frequency however the front suspension geometry on the goblin from DF does not include any anti-dive characteristics to stop the nose from hitting the ground under hard braking. By moving the front upper control arm mounting point up by 3/4" I should now have roughly 18% anti-dive with the car setup level front to rear. I can also adjust the anti-dive percentage by adding rake to the car by raising the rear suspension or lowering the front.
Ride Heights (Measured from center of LCA mounting point on chassis to ground):
Front: 9.3" (25% roll center height w/ 20mm LCA spacer)
roughly 20° of LCA travel from full droop (Binding) to point where RC intersects the ground plane
Flipped front LCA so shock mount was on top for more travel(only 14.5° stock) and easier ARB Mounting
Rear: 8.9" (17.5% roll center height w/ 20mm LCA spacer)
roughly 14.25° of LCA travel from full droop(Binding) to point where RC intersects the ground plane
Installed bump stops on rear shocks to shorten stroke where RC intersects the ground
This winter while measuring, studying, and modeling the goblin suspension I learned that when starting with the control arms horizontal we have very little room before our roll center becomes unpredictable. I brought this up to a couple fast engineers/drivers in SCCA and they noticed in pictures how the rear MacPherson strut going past level is very undesirable and the reason when cars are lowered they often use extended ball joints to fix the RC. By increasing the ride height all around to have some downward slope to the lower control arms and installing a spacer on the bottom of the uprights I have given myself more travel while keeping the actual chassis of the goblin at a relatively similar height to stock.
Front Anti-Roll Bar/Sway Bar
3/4" x 40" straight bar
Arms with adjustment from 3.5" to 8"
I believe personally that this sway bar will be the biggest performance boost for my setup. at the stiffest setting on my ARB the front axle weight transfer distribution is roughly 60% and I have adjustability all the way down to 40%. Stock from DF setup guidelines does have roughly 40% from weight transfer however the flat ride percentage is reversed with a higher frequency up front compared to the rear.
Alignment:
Caster: 5.5° (should be the same however I did not check after flipping the LCA)
Camber: -2° F(Max attainable after flipping the LCA for some reason), -2.5° R
Toe: 1/8" In
Alignment I tried to keep similar to last year except for the inability to get the front camber back down after adding the spacers and flipping the LCA. I slotted the rear BC coilover mounts a little more to fix my low camber in the rear. I actually am planning to decrease the front camber more after this test and tune after noticing the outside edge of the tire is not being utilized unless I set the tire pressure super low which when measuring the tread temperature was too low of a pressure.
First Test on New Setup
Now I am by no means a professional, I'd even be cautious about calling myself intermediate, but the difference between any other setup I've had and this one is in my opinion night and day. The car is still extremely responsive to my input but it is not trying to snap the rear end out constantly and even when i do slide the rear end out it is infinitely easier to recover from. I've attached a video of my fastest run from the test and tune which was 6th fastest raw time for the day and only 2 seconds behind an autocross national champion in a dodge viper.
I am an engineering student with a passion for motorsport that I have found over the last few years. I know I have a lot to learn but really feel like I made some progress with this great starting point of a chassis. Feel free to ask any questions or voice any concerns. I may entertain the idea of putting together some sort of group buy for a front ARB if there seems like a decent amount of interest in it.
Attachments
Desert Sasqwatch
Bigfoot Goblin
- Desert Sasqwatch Bigfoot Goblin
Kudos for figuring out the front suspension and raising the forward UCA mounting point by the 3/4 inch. I figured this out a few years ago and did exactly the same modification. Going from 0 percent of antidive to about 19 percent of antidive is a marked improvement. I went further and moved the forward LCA mounting point down by 1/2 inch and added about another 12 percent antidive for 30-31 percent total.
Adding this can cause the caster and possibly camber changes during braking and acceleration. The diverging angles of the UCA/LCA mounting points will make the hub upright move in a longitudinal arc rather than perfectly vertical. This arc, when acting with the lateral camber arc of the UCA/LCAs, can change the camber gain (or loss) during motion - it will not be linear and can add some geometry variability. The 5.5 degrees caster is about 2.5 degrees less than recommended by @Lonny. You may want to try adding more caster to see if it makes any difference, especially when transitioning from braking into a turn to acceleration out of a turn.
The rear strut suspension is really not ideal, especially if using the Cobalt subframe. It is setup for antidive for the front suspension of the donor and is prosquat on the rear suspension. The camber gain curve is far from ideal. I have to assume you have read about the tube subframe option from DF - or do you have one already? The LCA geometry has been adjusted to provide some antisquat and a slightly better camber gain curve. Using a strut suspension has been one of the limitations of the V1 chassis, which you are well aware of from your dialogue. This is the reason that @Lonny is making a UVA/LCA suspension for the rear of the V2. And why I'm working on designing one for my build too.
Adding this can cause the caster and possibly camber changes during braking and acceleration. The diverging angles of the UCA/LCA mounting points will make the hub upright move in a longitudinal arc rather than perfectly vertical. This arc, when acting with the lateral camber arc of the UCA/LCAs, can change the camber gain (or loss) during motion - it will not be linear and can add some geometry variability. The 5.5 degrees caster is about 2.5 degrees less than recommended by @Lonny. You may want to try adding more caster to see if it makes any difference, especially when transitioning from braking into a turn to acceleration out of a turn.
The rear strut suspension is really not ideal, especially if using the Cobalt subframe. It is setup for antidive for the front suspension of the donor and is prosquat on the rear suspension. The camber gain curve is far from ideal. I have to assume you have read about the tube subframe option from DF - or do you have one already? The LCA geometry has been adjusted to provide some antisquat and a slightly better camber gain curve. Using a strut suspension has been one of the limitations of the V1 chassis, which you are well aware of from your dialogue. This is the reason that @Lonny is making a UVA/LCA suspension for the rear of the V2. And why I'm working on designing one for my build too.
Keckster
Well-Known Member
- Keckster Well-Known Member
For the Anti-dive I think what I have now is pretty good. I drove the car before with the 220 springs on the front without the anti-dive and it would constantly bottom out under any braking. Now with the amount I've gained from just moving the UCA mount I hit the brakes hard from 70mph at the test n tune with about 1.2 Longitudinal gs without scraping.
Thank you for teaching me this as I did not think about how the caster would change as the suspension cycles but it makes perfect sense! If I'm imagining this correctly with my current setup I will be gaining positive caster in bump and losing caster in droop.
I understand the effects of caster with it's self centering nature as well as how it adds negative camber to the outside wheel. I'm not really sure how I ended up with 5.5° I thought I set it to DF recommended and just haven't touched caster since I first built the car... I will look into changing it to see if I notice any performance differences! As of right now I haven't had issues with poor self centering.
I do already have the tubular subframe. I am aware of the improved anti squat on the rear and my modeling was based off of measurements I pulled from the tubular subframe. For camber curve adjustments in the rear I may have a slightly different setup than others due to requiring shorter control arms for the f35 transmission.
Desert Sasqwatch
Bigfoot Goblin
- Desert Sasqwatch Bigfoot Goblin
Sounds like you are on top of this!
Post again if you learn something new. It may benefit the other track enthusiasts on the forum.
Post again if you learn something new. It may benefit the other track enthusiasts on the forum.
David
Goblin Guru
- David Goblin Guru
I have made a bunch of changes to hopefully improve the overall mechanical handling capabilities of my goblin. Lets start with a recap of the setup at the end of my 2025 season. I want to preface that I am not a professional in tuning or setup however, I have met many incredibly fast people and have worked with them to improve both my driving and setup.
2025 end setup
Spring Rate: 400F/550R
Damper Clicks: I honestly don't remember but 11 front 6 rear from softest keeps popping up in my mind...
I kept raising the spring rate around the car to help combat the amount of roll and oversteer the car seemed to have. I ended but getting a relatively stable car with this final setup however, it was way too stiff for anything but a perfectly smooth track.
Ride Height: LCA horizontal
DF recommended setup. I did some math and modeling of the stock setup and it leaves little room for travel before the roll center on our cars dips below ground which from my reading can cause some very unpredictable handling characteristics.
Alignment:
Caster: 5.5°
Camber: -3.2°F, -2.2°R
Toe: .15° (roughly 1/8")
Alignment seemed pretty good. I had struggled getting more rear camber due to what seemed like machining differences in the BC coilovers so I had just set it to the max that one side could do and set the other to match. I will be experimenting this year with decreasing the front end alignment after measuring the camber curve at the front end and observing the tire wear, temperatures, and pressures under racing conditions. From my roughly CAD design of our front suspension we gain about 0.4° of negative camber for every inch of wheel travel.
2026 Setup Changes
Spring Rate: 220F (2.0hz)/400R (2.6hz)
Flat Ride: 30% (47mph critical velocity)
Anti-Dive: Move front UCA mounting point up 3/4"
No Rake: 16.7 %
0.8° Rake: 21.4 % (Current Setup)
1.8° Rake 26.5 %
(Honestly not sure why I chose these angles for rake when I did my original math a while ago but I did confirm they are still correct
This spring rate change was something I tried before to get a more mathematically ideal ride frequency however the front suspension geometry on the goblin from DF does not include any anti-dive characteristics to stop the nose from hitting the ground under hard braking. By moving the front upper control arm mounting point up by 3/4" I should now have roughly 18% anti-dive with the car setup level front to rear. I can also adjust the anti-dive percentage by adding rake to the car by raising the rear suspension or lowering the front.
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Ride Heights (Measured from center of LCA mounting point on chassis to ground):
Front: 9.3" (25% roll center height w/ 20mm LCA spacer)
roughly 20° of LCA travel from full droop (Binding) to point where RC intersects the ground plane
Flipped front LCA so shock mount was on top for more travel(only 14.5° stock) and easier ARB Mounting
Rear: 8.9" (17.5% roll center height w/ 20mm LCA spacer)
roughly 14.25° of LCA travel from full droop(Binding) to point where RC intersects the ground plane
Installed bump stops on rear shocks to shorten stroke where RC intersects the ground
This winter while measuring, studying, and modeling the goblin suspension I learned that when starting with the control arms horizontal we have very little room before our roll center becomes unpredictable. I brought this up to a couple fast engineers/drivers in SCCA and they noticed in pictures how the rear MacPherson strut going past level is very undesirable and the reason when cars are lowered they often use extended ball joints to fix the RC. By increasing the ride height all around to have some downward slope to the lower control arms and installing a spacer on the bottom of the uprights I have given myself more travel while keeping the actual chassis of the goblin at a relatively similar height to stock.
Front Anti-Roll Bar/Sway Bar
3/4" x 40" straight bar
Arms with adjustment from 3.5" to 8"
I believe personally that this sway bar will be the biggest performance boost for my setup. at the stiffest setting on my ARB the front axle weight transfer distribution is roughly 60% and I have adjustability all the way down to 40%. Stock from DF setup guidelines does have roughly 40% from weight transfer however the flat ride percentage is reversed with a higher frequency up front compared to the rear.
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Alignment:
Caster: 5.5° (should be the same however I did not check after flipping the LCA)
Camber: -2° F(Max attainable after flipping the LCA for some reason), -2.5° R
Toe: 1/8" In
Alignment I tried to keep similar to last year except for the inability to get the front camber back down after adding the spacers and flipping the LCA. I slotted the rear BC coilover mounts a little more to fix my low camber in the rear. I actually am planning to decrease the front camber more after this test and tune after noticing the outside edge of the tire is not being utilized unless I set the tire pressure super low which when measuring the tread temperature was too low of a pressure.
First Test on New Setup
Now I am by no means a professional, I'd even be cautious about calling myself intermediate, but the difference between any other setup I've had and this one is in my opinion night and day. The car is still extremely responsive to my input but it is not trying to snap the rear end out constantly and even when i do slide the rear end out it is infinitely easier to recover from. I've attached a video of my fastest run from the test and tune which was 6th fastest raw time for the day and only 2 seconds behind an autocross national champion in a dodge viper.
I am an engineering student with a passion for motorsport that I have found over the last few years. I know I have a lot to learn but really feel like I made some progress with this great starting point of a chassis. Feel free to ask any questions or voice any concerns. I may entertain the idea of putting together some sort of group buy for a front ARB if there seems like a decent amount of interest in it.
Following, not at the suspension tuning yet but ill be there very soon. So keep it up and ill have to pick your brain when its time. Sure seems like your on the correct path.
Also would love to know more about your rewiring. Didn't get to it this winter but definitely on for next winter. Would like to rewire everything nicely.
Rttoys
Smokin' Goblin
- Rttoys Smokin' Goblin
I was R&Ding and making/changing parts a ton in ’24. So much I couldn’t tell you what worked and what didn’t. In ‘25 I decided to just drive and have fun. Now I’m ready(ish) to get back into fixing things, so these are good findings.
I’m also surprised your caster is so low. Everyone is in the 8-9 range or more. Might be something to play with.
Definantly need a front sway bar. That was in the works when I took my break. Glad I have another visual to work with.
As you know, the rear strut system is one of the biggest holdbacks of the goblin. looking at pictures of our rear suspension compressed in a race is pretty shocking. An upper control arm and spring/shock is definitely the way to go, but it’s gonna take some work. The Df subframe is a good start to build off of though.
the camber seems pretty extreme, but if you can get good roll, then it’ll work. I have my front hitting both ends of the tires, but rear I’m going to have to move around due to new tires that grip better and such. It’s all part of the game.
I’m also surprised your caster is so low. Everyone is in the 8-9 range or more. Might be something to play with.
Definantly need a front sway bar. That was in the works when I took my break. Glad I have another visual to work with.
As you know, the rear strut system is one of the biggest holdbacks of the goblin. looking at pictures of our rear suspension compressed in a race is pretty shocking. An upper control arm and spring/shock is definitely the way to go, but it’s gonna take some work. The Df subframe is a good start to build off of though.
the camber seems pretty extreme, but if you can get good roll, then it’ll work. I have my front hitting both ends of the tires, but rear I’m going to have to move around due to new tires that grip better and such. It’s all part of the game.
