V1 David K's Extended Track Goblin #343 - 06 SS Donor

[Keckster]

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.

That is exactly how I felt last year. I did not engine or suspension changes and did 2-3 events a month for 2025. After getting a bunch of very experienced autocross and track guys to drive the car I gained a lot of suggestions and ideas on improving the car. The biggest issue was the balance of the car was too tail happy with "theoretical" good spring rates at each corner.

I’m also surprised your caster is so low. Everyone is in the 8-9 range or more. Might be something to play with.

Yeah I honestly wish I took better notes on some of the changes I made. I know I originally built the car with 8.5° of caster and looking back through text messages with my race car friends I only found one instance where we talked about my caster being high and then a few days later I sent a picture of my new alignment settings with the 5.5° just before Mid Atlantic Car Fest 2025. TBH I don't think being at 5.5° is currently an issue for me, Car drives straight as an arrow at triple digit speeds and isn't heavy to steer. Doing some research since Mr Sasqwatch noticed my caster number I think a low number could possibly help the goblin.

Here a snippet from the website suspension secrets which outlines two problems the goblin already seems to struggle with that the lower caster could be helping with slightly. On the 2025 setup when I would get a good run out of a corner I did notice lifting the rear inside tire causing the diff to unlock.

Definantly need a front sway bar. That was in the works when I took my break. Glad I have another visual to work with.

This is the golden ticket for our cars and even with just 18 runs on the new sway bar I can already tell you how much safer and more confident the car feels. Now I just need to get rid of some poor driving tendencies I have developed from before the setup change. I may consider putting together a group buy of my setup.

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.

Yeah the Macpherson strut if definitely a crutch we sit on but to be fair DF made an awesome kit within a great budget range for the market and they had to do what they could at the time. I don't think the strut in the rear will actually be that big of an issue once we get it figured out. I've been talking to a bunch of really fast FWD engineer type guys and they were adamant to make sure to verify our roll center stay above ground and is at a good static height which is why I added the spacers to the wheel hubs and added collars to limit my maximum bump travel.

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.

Yeah we do not need much negative camber in the front, Based on tire shoulder lack of wear and how low air pressure I need before the shoulders get used, which is on my list to modify before my next event.

 

[Rttoys]

Since we are shut down right now on autocross, only test track I have is streets here near the house and you can’t push near as hard on the street.

I remember moving my castor around years ago, but I don’t remember the results and I didn’t take notes on it.

I made a rear sway bar for the Df subframe, but it really messes up the handling. It won’t be needed until a front is installed. I still stand by a soft rear sway bar in the rear with stock subframe, especially on the street. It’s much nicer to drive.

I'm getting good tire roll and total use of the tire up front being at roughly -.5 to -.8 camber. In the rear, I have always had awkward findings. Now with stickier tires, I’m using the outside edge, but not the inside. I’m around -.8 in rear, but will move it in to maybe -1.3 to -1.5? Not sure yet, I need to drink about it.

 

[SmsDetroit]

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.

Do you have a parts list for your sway bar as well ast a write up

 

[Keckster]

Do you have a parts list for your sway bar as well ast a write up

I do not have a write up on it yet but will put something more together after a couple events to verify it works well