V1 Pisco's extended city goblin #220 (2009 SS/TC donor) Registered

[Gtstorey]

I wonder what he was basing the "too much camber" on? Does the car return to center at speed?

 

[pisco]

I wonder what he was basing the "too much camber" on? Does the car return to center at speed?

Caster he was saying that the recommended 8.5 was alot and 6 would drive better
I don't know if he realized the front end has such little weight on it

 

[pisco]

Not likely an issue of lack of downforce in the rear.

I agree I don't see a reason to have rear downforce in this car until there is enough up front to counter it
9LR makes a front wing that some have installed I'm debating which way to go with it splitter or front wing...

 

[Gtstorey]

This is more likely to mostly still be an alignment issue. I don't think any of the DF direct built cars have had front wings or splitters.

 

[Desert Sasqwatch]

Has this guy done an alignment on other Goblins? Probably not. The values provided by @Lonny are the 'factory settings', so he is one deviating by going with his own opinion on values. Also know that the decreased caster setting will be even more exaggerated when getting into the brakes hard - the nose will dive and the relative angle of caster will be reduced even more. As @Gtstorey asked, does the steering wheel self-center from turning? Does it self- center (still) when braking in a turn?

 

[pisco]

I also just popped out to the garage to take a look and check everything
the torque paste isn't broken on any of the inside heim joints so I don't believe they adjusted caster
the lower right outer joint was finger tight ( I got a full revolution + 1/8 before torque wrench clicked)
this makes me think they adjusted camber and toe only every one of these were also clocked all the way as if they didn't back them up while tightening the jamb nut and the joint was jammed up on the washers...
would this cause damage? I never noticed grease coming out of the joints before now.

 

[pisco]

Has this guy done an alignment on other Goblins? Probably not. The values provided by @Lonny are the 'factory settings', so he is one deviating by going with his own opinion on values. Also know that the decreased caster setting will be even more exaggerated when getting into the brakes hard - the nose will dive and the relative angle of caster will be reduced even more. As @Gtstorey asked, does the steering wheel self-center from turning? Does it self- center (still) when braking in a turn?

I didn't give it a chance it seems to be pulling right but that may be from the crown on the road I was on...
I'm not comfortable driving it on the highway at this point it was almost impossible to keep it between the lines at 80


Called the shop and they must be closed for the day
I'm pretty unhappy right now and just want to walk in there calm with facts in hand

 

[SmsDetroit]

I run mine at 7.5 deg of caster. 1.5 deg camber and 1/8’ toe in. Without my front splitter im stable up to about 90mph. With front splitter ive been 125mph and felt planted. All of this occurred in Mexico of course. Also i have done all my own alignments. The 2 times i did it with weight in the drivers seat i did not like the outcome. I know weight plays a big part in how these cars drive so i know some people do theirs with weight in it. I love how it drives. Steering wheel self centers after turns. It doesn’t wonder. Come on up to Michigan and ill give you a hand

 

[pisco]

I run mine at 7.5 deg of caster. 1.5 deg camber and 1/8’ toe in. Without my front splitter im stable up to about 90mph. With front splitter ive been 125mph and felt planted. All of this occurred in Mexico of course. Also i have done all my own alignments. The 2 times i did it with weight in the drivers seat i did not like the outcome. I know weight plays a big part in how these cars drive so i know some people do theirs with weight in it. I love how it drives. Steering wheel self centers after turns. It doesn’t wonder. Come on up to Michigan and ill give you a hand

before this morning's adjustments it was stable and felt fine up to about 140 now I can't keep it on the road at 80
also in mexico of course

 

[pisco]

Not sure why but I also noticed considerably more wheel spin in 1st - 3rd after adjustments
it felt loose in back and didn't want to track straight under hard acceleration

 

[Gtstorey]

Assuming it's the top number in your screen shot, looks like too much camber. Depending on type and condition of bushings, you need closer to zero camber.

 

[Joebob]

Do you have solid bushings in the rear lower control arms. I noticed a fair amount of compliance in the rubber in the rear bushing such that with the parking brake on, and rocking the frame forward and back, I could see a significant movement in the bushing, this translates to toe in on acceleration and tow out on braking which is highly unsettling. I suggest you have the rear set at a healthy toe in to ensure you never break out into negative or toe out. Should help a bit on stability.

 

[LaunchPad]

Caster he was saying that the recommended 8.5 was alot and 6 would drive better
I don't know if he realized the front end has such little weight on it

this here is one issue. . . you said unstable at speed. . . this could do it very easily. . .here is why

Very short wheelbase car- the roads around our area (Omaha for both of us) are much less than desirable. Any bump on the road (or hard braking/acceleration depending on anti dive, etc) would significantly change that caster number and the front wheels then start to act like a broken shopping cart.

The only real reason to have a lower caster number is if you have significantly WIDER than normal tires and no power steering with a heavy car because then you are using your arm muscles to raise the whole car up when you turn the wheel. in a goblins case only one of these might apply.

Now my vehicle dynamics book from way back in Mechanical Engineering undergrad said you average passenger cars (much longer wheel base) tend to be 7.5- yeah it is probably dated but the 8.5 recommended sounds very correct given the short wheelbase, light weight and all. I haven't run any numbers on the Goblin yet but several folks have hopefully some pitch in.

 

[Gtstorey]

this here is one issue. . . you said unstable at speed. . . this could do it very easily. . .here is why

Very short wheelbase car- the roads around our area (Omaha for both of us) are much less than desirable. Any bump on the road (or hard braking/acceleration depending on anti dive, etc) would significantly change that caster number and the front wheels then start to act like a broken shopping cart.

The only real reason to have a lower caster number is if you have significantly WIDER than normal tires and no power steering with a heavy car because then you are using your arm muscles to raise the whole car up when you turn the wheel. in a goblins case only one of these might apply.

Now my vehicle dynamics book from way back in Mechanical Engineering undergrad said you average passenger cars (much longer wheel base) tend to be 7.5- yeah it is probably dated but the 8.5 recommended sounds very correct given the short wheelbase, light weight and all. I haven't run any numbers on the Goblin yet but several folks have hopefully some pitch in.

And then you have to add in bump steer on top of that. Mine had a bunch at first.

 

[Desert Sasqwatch]

Not to pile onto this - and I have said this before - the Goblin V1 has parallel mounted from a-arms, so no anti-dive geometry. Hard braking will push the nose down until the shocks or springs are fully compressed (or the nose hits something). Compounding this is the pro-squat geometry of the Cobalt donor rear suspension. The 8 degrees of caster will lose probably 2-3 degrees under hard braking. Add in any flex in the a-arms, bushings, or frame and the caster is likely half what it is set to. This just the front suspension. The rear suspension has no anti-squat, since it's factory geometry is set up for anti-dive in the front of the donor Cobalt. The angle of the a-arm mounts, plus the aforementioned bushing movement leads to the lower control arm moving back a forth and the rear tires changing angle in the wrong direction for braking and acceleration. The DF tube subframe and suspension was designed to help fix this. If you plan to compete with your Goblin, It is something to look into for the rear suspension. A front suspension improvement would require physical changes to the suspension mounts for anti-dive improvement.

 

[Gtstorey]

Don’t let all the suspension design talk get you down. I’m very happy with how my Goblin handles for spirited back road driving. It may not be perfect but still handles well with proper setup. I eliminated bump steer, and better bushings in the rear and the adjustable Saturn Vue power steering. I do have a front wing but I think it’s more for looks than anything handling.

 

[pisco]

Spoke with the shop owner the day after and he agreed to make adjustments but wants to be there for it on this car and will be out of town all next week.
I may add some caster in myself in the garage and bump up the toe in on the rear also looking into the prothane bushings and noticed zzp and ottp both sell a solid spherical joint bushing. I don't know what direction to go if I'm replacing the rear sub frame and suspension this fall I don't want to spend a fortune on what I have now... I also need to find a new set of wheels to go wider in the back the search is back on for decently priced wheels with the proper offset

 

[Gtstorey]

MOOG K201285 Problem Solver for the spherical in the rear of control arm. I did get the OTTP for the front.
More Information for MOOG K201285

 

[comegetjoe]

I've got a brand new set of them in the boxes, Im never going to use them on my build. Pm me.

 

[Rttoys]

I believe it needs more caster too. I would also bring the camber to around -.8 to -.5. I know DF recommends -1.5, the tires just don’t seem to make enough contact with that much neg camber. Around -.5 seems a lot better.

plus, don’t forget to get your tires pressure down. They may have brought them up to 32 psi like cars normally are, but a goblin is so light, you only need 20psi at the most.