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When C7 came out I did not realize how important being at 0.0 or positive caster was when it came to not having snap oversteer, I actually ran positive 2.4 both sides and oversteer was definitely long gone - hopefully I can give my rear caster tools away with the C8 - anyone know ??? Thanks
When C7 came out I did not realize how important being at 0.0 or positive caster was when it came to not having snap oversteer, I actually ran positive 2.4 both sides and oversteer was definitely long gone - hopefully I can give my rear caster tools away with the C8 - anyone know ??? Thanks
It appears to be the same as the C7. Maybe someone can post pictures of the lower control arms. I revised my upper A arms in my C6Z and relocated them as shown below to achieve pos. caster and camber gain in droop. I made them from steel tubing with 3 Heims. You can't believe what a pleasure it is to drive. I can get on it real soon out of turns without any unpredictable results. Beats me why the C5, 6 and 7 have this design.
The C8 looks different, although I can't explain the neg. camber in the picture below, but I fear setting the rear with those dumb eccentrics is going to be a compromise once again.
My C6Z lower control arms have solid shim box mounts and all adjustment, except for initial installment is fixed. It is all done at the top. I removed 2 degrees out of the squat geometry also. I altered the mount point of the steering arm and dialed in some roll under steer.
C8 rear and front suspension. C8 lower control arm appears to have eccentrics like the C7 has. Maybe some one has a photo. C7 eccentric camber caster adjustment. Upper fixed. This is what happens in droop with the geometry on a C5 C6 and C7. Although in the pictures provided, the geometry looks correct, it beats me why there is neg. camber here. Note position of upper A arm, fixed. C8 upper control arm fixed at mount points same as C7. Note ride height adjustment. C8 A arm mounted differently. C7 incorrect. Yellow is correct like C8 has. You may have got ideal + caster settings but maybe it is at the expense of camber and steer settings. Each car is different and in some cases, the track settings can't be achieved. It also causes binding and stiction. I'm afraid the C8 looks like it has the same dumb eccentrics. Lock in the bottom A arms and fabricate uppers with 2 Heims.
It appears to be the same as the C7. Maybe someone can post pictures of the lower control arms. I revised my upper A arms in my C6Z and relocated them as shown below to achieve pos. caster and camber gain in droop. I made them from steel tubing with 3 Heims. You can't believe what a pleasure it is to drive. I can get on it real soon out of turns without any unpredictable results. Beats me why the C5, 6 and 7 have this design.
The C8 looks different, although I can't explain the neg. camber in the picture below, but I fear setting the rear with those dumb eccentrics is going to be a compromise once again.
My C6Z lower control arms have solid shim box mounts and all adjustment, except for initial installment is fixed. It is all done at the top. I removed 2 degrees out of the squat geometry also. I altered the mount point of the steering arm and dialed in some roll under steer.
C8 rear and front suspension. C8 lower control arm appears to have eccentrics like the C7 has. Maybe some one has a photo. C7 eccentric camber caster adjustment. Upper fixed. This is what happens in droop with the geometry on a C5 C6 and C7. Although in the pictures provided, the geometry looks correct, it beats me why there is neg. camber here. Note position of upper A arm, fixed. C8 upper control arm fixed at mount points same as C7. Note ride height adjustment. C8 A arm mounted differently. C7 incorrect. Yellow is correct like C8 has. You may have got ideal + caster settings but maybe it is at the expense of camber and steer settings. Each car is different and in some cases, the track settings can't be achieved. It also causes binding and stiction. I'm afraid the C8 looks like it has the same dumb eccentrics. Lock in the bottom A arms and fabricate uppers with 2 Heims.
Watch what Pratt and Miller does.
Thanks a ton !! I got the alignment numbers I wanted once I removed the shims/washers from behind A arms . It’s funny my car isn’t showing up till March ? And I’m already doing a alignment! Lol
Looks great but often not repeatable on every car. I found a pic of the eccentric camber caster adjustment on the rear. Won't do on the 600-800hp cars or the high downforce packages.. My order went in Thursday And with your help I’m already pulling my shims . These pictures really helped me understand, thanks again.
Looks great but often not repeatable on every car. It will be no different on the C8. I found this a image which shows lower A arm adjustment. You can see the cam (eccentric) adjustment for camber/caster and tow adjustment. I would place shim blocks on lower A arms. The top will be mine with 3 Heims. I may have to relocate the tow arm. Fail. I'll hold off on the front till I am done with the rear. See video. I don't see how you can change ride height without changing preload here. I would keep stock ride height on the Z51. You always screw up geometry if you do, even with 1". Aero package is different where I would go max pre load. Check out this structure. What were they thinking at the rear? High CG and poor load paths. This would make it much stronger and lighter. Or this. I can set everything including motion ratios. I would have liked to have seen something like this. I send the shock company all my specs and they make the coil over accordingly. They tune the shock and give me clear parameters including pre load which I always adjust to my liking.
If I had to change ride height, I would turn the replacable bottom threaded mount but these are custom C/Os. There are some advantages to pull rods. Modifying factory chassis and suspension is much more difficult than scratch designs. I look forward to messing with the C8. May sneak a few photos from the Pratt and Miller car first.
Oh god... Shaka's "Corvette engineers are morons, I know more about suspension design than all of them" posts...
OP.... it appears the car will have eccentrics at both ends of the rear LCA which means caster can change if not measured when adjusting rear alignment. This affects bump steer curves aka roll steer. Whether or not the same caster gauge will work with the new spindle design is yet to be seen.
A more economical rear-caster measurement solution is as follows:
1) Buy two 0.4330" size "go" gauge pins, part #23055A002 at https://www.mcmaster.com/catalog/126/2427. These are an exact fit for the machined holes in the C8’s rear uprights/knuckles. $4.08 each
2) Buy one nickel-coated low-carbon steel bar, 1” x .125” x 6” at https://www.mcmaster.com/catalog/126/3920, see: 8131K35. $11.55 each (non-nickel plated cost less if preferred)
3) Buy a Wilex angle gauge (0.1 degree accuracy), see:
A more economical rear-caster measurement solution is as follows:
1) Buy two 0.4330" size "go" gauge pins, part #23055A002 at https://www.mcmaster.com/catalog/126/2427. These are an exact fit for the machined holes in the C8’s rear uprights/knuckles. $4.08 each
2) Buy one nickel-coated low-carbon steel bar, 1” x .125” x 6” at https://www.mcmaster.com/catalog/126/3920, see: 8131K35. $11.55 each (non-nickel plated cost less if preferred)
4) Install rubber bands to hold tool steel bar on the pins (it isn't necessary to tap rubber band holding-screws)
These pictures were taken after the removal of the rear brake cooling ducts.
a little help please, this is first I see the bar is lateral instead of horizontal how do you know if you positive or negative? My guess is the bar toward the front of car should be higher up for positive caster ? Thanks for you help
Yes, if the front of the bar goes "up," then you have moved positive; although "zero" degrees is the goal. Remember to "zero out" your gauge on the alignment rack as the first step. For increased accuracy, if your angle gauge will be attaching upside down (as is mine in the picture), zero out your gauge upside down on the alignment rack as well.
Yes, if the front of the bar goes "up," then you have moved positive; although "zero" degrees is the goal. Remember to "zero out" your gauge on the alignment rack as the first step. For increased accuracy, if your angle gauge will be attaching upside down (as is mine in the picture), zero out your gauge upside down on the alignment rack as well.
thanks for your response ( help) I understand 0.0 is recommended but I have learned the more positive caster I can get the less oversteer I get with my extra tow in I run in rear on C7’s - I will start about 1.5 positive on c8 and see how it feels , thanks about for your response.
With the stock 4S tires (however upgraded GiroDisc rotors and Raybestos ST-43 pads) I've run three days at Mid-Ohio and another three days at Road America, all with the factory recommended 0.0 degree caster and the balance throughout the corner was amazing. Heading for Watkins Glen on 7/24-26/20 now shod with BCForged wheels and Cup 2 tires.
long story short, I have unlimited access to alignment rack and started at 0 and learned the more positive rear caster the less oversteer I have especially the dreaded snap oversteer I started with when I had negative on one side and positive on other . Worked on my c7’s and now works on my c8 . Side note always run some if not a lot of rear tow in some people were following blindly a shock company suggesting Static tow out in the rear . Nuts !
Does C8 still have rear caster adjustable ?
