I have a 69 Vette that I road race and it has always performed excellent. However last year at Road Atlanta the car performed perfect and the power steering went out. I like the car so much without power steering I removed the power steering and shortly afterwards went to Daytona. With no other changes to the car, it no longer will come out of a flat corner. Even at a car show this year (held at a track) we were allowed to take some show laps and I could tell even at slow speeds the car would not come out of the corner. It brakes and turns in good but when applying power to exit the corner it wants to push. Now the question, any ideas as to the direction I should take. Softer rear sway bar? Stiffer rear? Softer front spring? I hate to waste an entire track day chasing the wrong formula. And I surely hate to go to a race chasing a pushing car. Any help as to a direction to take to help save some time in testing? Thanks Mike W---

 

For road racing sometimes the corvettes handle better without a rear sway bar. Its easy to remove, I run mine at Road America without one and it handles great.

 

With the rear evidently hooked up well on corner exit, I'd suggest working to try and bring the front end up to even par before resorting to stiffening up the rear to reduce it's grip. Yes, a lot of hard runners have no rear bar (), but removing it isn't going to fix corner exit understeer, rather potentially make it worse depending on how early you're attempting to put down power.

So, it would be good to know a good deal more about your front end setup and any mods you've done and/or may be allowed; i.e. static alignment, bumpsteer, ride heights, corner weights, bushing and link materials, OEM or other CA's, springs, bar(s), shocks and how adjustable they may be... Also, when you converted to manual steering, did you replace the pitman arm and drag links to HD manual bits?

Shy of knowing more about your car, assuming there's no geometry or chassis flex issue causing mid-corner understeer that's going undetected until you begin hard acceleration (as opposed to maintenance throttle), if you have adjustable shocks the first thing I'd try would be to stiffen front rebound to slow weight transfer off the front wheels. IMCO, if you don't have at least 2-way adjustable shocks, I'd budget ~$2K for a set ASAP and get in touch with someone such as KONI NA Racing (ask for Gordon) when you're ready to step up.

Otherwise, one step less front bar may help on exit, but at the expense of some responsiveness on turn in and risk of corner entry oversteer. Hard to say much more at this point, but at least you've identified the issue far better than the usual "I want my car to handle better". Hope that's worth something. (I take PayPal, btw )


TSW

 

Soften the front bar if you can, and I agree with increasing the front rebound on the shocks also. A little more rake might help. As TSW said bump steer, camber and toe can also make a big difference.

Different tracks also can widely effect the handling of the car depending on the surface, age, temp, sun, altitude and time of day.

 

Just a thought, I know nothing about road racing compared to these guys but when changing to standard steering you might have tweaked the alignment a bit in the front wheels enough to make a difference on the track

 

I bet the front tires are used up. replace them . go back to lower pressure.......Hope thats an easy fix.........bryan.

 

Thanks for the time and information. Very well stated Skunkworks. At least now when I go to a track day in a few weeks I will have a few directions to try. Some of them I had already thought of as a possibel problem, I just wanted to confirm my ideas. Thanks again for taking the time to help. Mike W----

 

Glad we could help. Good luck, and do post up with results.

 

The rear bar links should be shortened and stiffened.

 

I'm quite curious as to 1) how you know they're too long and too compliant, and 2) why this mod would specifically help improve front grip when accelerating out of a corner. If I've missed something, please fill me in...

 

I think Skunkworks is on the right track. I did replace the drag link, but did not replace the pitman arm. I got a new one but it looked just like the power steering one to me so I did not replace it. Must be some difference I could not see with the naked eye. I also did not restring the car to check alignment. I trusted marking the threads for the car to be back where it was (pretty dumb looking back now). I am going to replace the pitman arm and totaly re-align the front end. then make adjustments if needed from there. I think this will be a good start to fix the problem. Again thanks for all help and input. back to work !

 

I do not have adjustable shocks either, sounds like a few bucks spent in this area might be a very good investment. Thanks again

 

I'm surprised your having the type of issue with your vette as my 80 has a bad oversteer problem which most early vettes seem to have (rear bar removed). Let us know what happens and for sure check the alignment.

Have you measured wheel to wheel center front to back? I barely clipped a curb many years ago and didn't realize the A-arm had been bent. Found it when the passenger wheel was 3/4 inch further back than the drivers side. Also check to make sure the mounts for the lower control arms haven't become bent or breaking away from the frame if not previously re-inforced.

Oh and the best mod a I made to my car to get it to handle was the VBP front leaf spring kit with control arms. This and adjustable shocks was the best mod ever for me but other have differing experiences. I'll be going coil overs in the front at some point but from a simple bolt I liked the VBP front kit and I did it back 90/91

 

Whats the alignment like, maybe you have too much toe in, the two center links could easily be off a little and and would be exaggerated at the tires

 

As the complaint was isolated specifically to corner exit, and toe issues would usually show up on the turn in and entry phase, I wouldn't think that's the likely issue, unless due to bumpsteer.

Yes, IMHO any race car should have adjustable dampers, as they provide for much more tuning. Heck, I've got adjustable KONI's on my street shark, tho they're only Special-D's, but have 2-ways (I'd love 4-ways) on my wish list.

 

I agree that indeed if you have changed the drag link , I would double check the alignment again. You did not mention it , but , there are two
positions on the steering spindles that the tie rod ends can be place in..
One for manual , one for power steering ???

 

does your front sway have adjustable spring end links? Are you using shorter stiffer springs like the VB&P? Are you running Zero toe to 1/8th out. Is front camber setting -.50 to - 1.00. Have you installed a bump steer kit?

It's not easy on our Vettes, but adjusting the rear toe can really change how the front end acts

 

Wow thanks , without a lot of back and forth I can say you are all over the problem. I run the rear with 0 toe and the front 1/16 out on each wheel total of 1/8. I have VBP front and rear springs, the front does have several adjustments ava. It is set to the stiffest adjustment right now. Again thanks for all the input.

 

I ran Zero rear toe for many years with a 3/4 rear bar and 420# custom steel. I removed the rear sway and I'm convinced now that 1/8 is good for hot weather RR. I can pull in and have over 175 degrees in the rear hoosier 335/18 slicks.

I was trying to think about how to best explain my VP3 SCCA Vette. The only time I ever get push is from too high of cornering speed. Any time in the turn push for me is just to much speed and it's the off the gas push where you just wish that the front tires would bite as the front end is headed to the outside of the turn.

Now under power front end push can be accomplished if you are inducing rear weight x-fer by going WOT with a powerful motor out of slower turns with max rear traction.

I'd really also take some measurements and figure out front bump steer. I really recommend the BS eliminator kit. You want to make the most use of your front tires at all times.