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Increased caster pretty much eliminates that loose, darty feeling when driving at speed
"Loose and darty" is exactly how I'd describe it. I thought it might be insufficient toe-in. Haven't got an alignment shop in this tiny town, will have to wait for the big city.
It helps if you can be more specific on what the car is not doing that you want it to do. After many time trials at Bridgehampton, I can tell you what worked for me. YMMV
First, I started with the basics, replaced the entire suspension, ball joints, tie rod ends, etc. Better, but not close to what I wanted. I tried many sway bars. They can have a huge effect on the way the car handles.
I should add here that my car is almost rubber free. The upper and lower control arm bushings I purchased from Guldstrand are solid. They were also offset, which allowed me to get a better alignment with more camber. The sway bar, again Guldstrand, is held in by aluminum blocks and Heim joints.
The rear had too much trailing throttle oversteer. The car was nuts if you lifted after the main straight of Bridgehampton at over 100 MPH. I took the rubber out of the rear control arms and replaced them with Gulstrand Spherical bushings and replaced the camber arms with Guldstrand solid arms. This allowed for better alignment.
I felt the springs were too soft, so I purchased the Chevrolet Daytona suspension front and rear. I proved to be a bit too stiff and went with the F-41 suspension front and rear.
For shock I now have Bilstein’s. I liked the original Koni’s better.
A HUGE change, as other have mentioned is tires. I went from the stock size, to 17 inch rims. Yes, had to flair the fenders to fit them. The rears are 335/35X17. The fronts are 275/40X17.
I want to add here, there was a lot of trial and error. I have 3 or 4 sway bars in my attic that didn’t work. I have multiple springs that didn’t work.
Alignment, I have tried more settings that you can count.
One important thing I forgot to add. A huge improvement was when I installed new springs (The F-41) and my ride was height was higher in the rear. I took the car to do a Time Trial at NJMS (Lightning). The car did not handle well. My friend who is a certified instructor and driven numerous Corvettes of all years initially told me the car was "possessed". I was reading my Chevy power book in regards to setting the “D” height.
I noticed the rear half shafts were not parallel to the ground. I found my D height was off (it was over 2 inches) and I have ordered longer rear spring bolts to get the back down and get the proper D height. I personally found that 8 inch were too short. I used 10 inch and when the proper D height was set, I trimmed the excess of the bolt with a Dremel. Someone correct me if I am mistaken, but I think non-tracked cars the D-Height should be 1.6". I used the racing spec of 1.2". BTW: This should be performed with a full tank of gas and weight equal to you own in the passenger seat.
225-70-15's, Moog bushings, stock suspension, Delco shocks, I drove 5900 miles last year and 4800 the year before. I drove to Carlisle (from home) with the club members C8's and C7's for the 50 year anniversary display and to Carlisle each year. I do many long trips. For street use the car is fantastic. The Borgeson kit made the car a pleasure to drive. This year I only put 3k miles due to getting a C8 Z51 in December . Since I do long trips, I wanted parts that could be replaced if something failed while a few hundred miles from home.
Just a note, most aftermarket front springs are not "progressive" like the factory springs and even though the handling is better, they may result in a rough feel on washboard roads.
The front stiffener cross bar does help, if you like to "push" the car in corners.
First it was Van Steel's coilovers- then I went with a Flaming River Manual rack and pinion- then added electric assist. Used a Nissan Cube set up.
Love the feel- parking is soooo easy and at speeds there is no assist. Best mod I have done and just sayin I have done a few!
Your method of adjusting the box I have never heard before. The only method GTR1999 has ever mentioned, usually the box needs a rebuild, is to center your steering wheel, look under the hood at the steering shaft above the rag joint and make sure the flat surface is pointing straight up, if not adjust steering wheel, loosen lock nut and tighten screw till it stops but do not apply force, tighten the nut.
Dont think it was mentioned above, but a spreader bar helps.
Op… i thought you said ball joints replaced and aligned? Do you have the printout mentioned earlier in thread?
i have ZERO track experience and my comments are to your loose darty comments..
i would look very closely at ALL bushings but particularly the rear strut and trailing arms.
i would also research heavily the experience of the alignment shop especially adjusting the rear. They will not have the correct shims you need to buy some. If you find the right guy stick with and tip well. Even chains may have some competent guys like i found.
I have basically OEM components and the factory best (reset in picture) alignment specs and have zero issues with street performance even hard turns. I am not saying more castor etc wouldn’t be helpful but I’m not sure i would change a thing on mine..it drives down the road and steers stable like a new car.
i thought my rear bushings looked worn but not that bad??? Guess wrong
The Borgeson conversion is by far the best thing I've done to make my car steer better. Replacing my stock front sway bar with a QA1 is the best thing I've done for handling.
If you want a C3 with 'great handling', prepare to spend $$$ and do a lot of work underneath. The C3 platform is basically a 1950's Chevy 'ladder' frame and steering system. You can "do the deed" and modify the C3 to get handling like a C4 [and somewhat later models]. But it's much easier to just buy a C4 to play with for steering fun.
If you want a C3 with 'great handling', prepare to spend $$$ and do a lot of work underneath. The C3 platform is basically a 1950's Chevy 'ladder' frame and steering system. You can "do the deed" and modify the C3 to get handling like a C4 [and somewhat later models]. But it's much easier to just buy a C4 to play with for steering fun.
Interesting option for sure.
Would agree the path to a C3 that handles like a modern sports car and is not too harsh is an interesting path, and one that can be expensive in both time and money. But if you can get there it is worth it.
Had my 71 out today and it sits low, handles great and just soaks up all but the biggest road irregularities, however, I am still on that elusive journey to something that may not exist.
Am about to rework the front end again with full coilovers from my semi coilovers I have now. Will be interesting to come back to you all with my findings. Sometimes the $ cost is worth it even though logically it does not stack up 😀
And I have a factory gymkhana car that I have modified slightly, still with factory front springs although cut. And it's a bloody weapon.
slightly bigger rear sway bar. Offset and slotted Upper A arm shafts. (Thanks Leigh) Factory Bilstiens replaced with modern Bilstiens. Poly bushings in A arms and all sway bar bushings and links. Composite rear spring, and a few other tweeks. And it really handles. So, maybe I've learned to drive it over the many years. Or maybe I have it dialed in fairly well.
maybe a bit of both.
I've owned 3 C4's. They are indeed a better start. But. Nothing looks as good as a C3. So we do the best we can.
I think track time will help sort out a car. Doing HPDE or Time Trials taught me a lot about handling and knowing the pluses and minuses of my car.
That is why I often ask people that want to do modifications “What is the car doing (or not doing) that you want to change.
Wadenelson gave us some info when he said It "lurches" more than it steers around a corner. I actually have to give it a little gas to "set" it into a curve --- I was instructed to "Steer with your right foot!" Which works, believe it or not!”
2020 Corvette of the Year Finalist (performance mods)
2019 C3 of Year Winner (performance mods)
2016 C3 of Year Finalist
I have a 68 without the rear supports so my frame was a bit flexy. I replaced all my ball joints, they are all the same age, along with tie rod ends. Tighten up your box like you said. I pulled mine apart and cleaned it. Usually there is zero slop in the box afterward but you can actually see it in the linkage afterward. Idler arm was replaced, they get overlooked. Make sure its tight too., i replaced the power steering valve when it leaked and moved the tie rod ends to the inner most hole on the king pin arms on the knuckle. A bigger front sway bar and bikstein shocks. Never a steering issue with my car. Drives like its on rails. Never understood how anyone could have all these steering issues.... Was very nice.
I eventually installed VBP suspension all the way around and jave it cranked up to the track settings with a big block in it. Felt pretty good with 225 15s but they were undersized for sure.
Stepped up to 17 inch after those and added a spreader bar. I couldnt say there was a huge difference but it felt great on the track....ran very flat
When i had a small block and had it on a track i couldnt out drive it. Had a heating issue that was solved by removing the headlight shields and openning the headlight doors that day. Realized i smoked the organic brake pads the next drive the day after.
Im back to 15 inch tires running staggered Coopers, still grip tight in the local turns. If you have issues i would check the frame on both sides where your steering box mounts and the power steering piston anchors, either they are loose or your frame is cracked....seen lots of that here on the forum.
With your engine running have someone rock the steering wheel and you should be able to see your linkage issues. Any small flex or stutter is an indication. Joints feeling good is not an adequate assessment. I never replace anything on a 50 year old performance car without replacing its mirror image......theres no reason not to, they have the same mileage
Last edited by Rescue Rogers; Sep 10, 2023 at 10:26 AM.
A good steering box rebuild might be in order (op) ..in addition to ensuring the bushings and everything else is good, or needs changing.
The C3 steering boxes are a manual box and frequently wear at the lower bushing and input bearing. Tightening the upper screw won't fix or resolve steering box slop *if* the above issues are present. The bearings/bushings are (relatively) easy to replace, but considering the time, yer almost better off letting someone who's done it rebuilt it. After a steering box rebuild, the steering can be super-tight and precise, as others have pointed out. Like the car was new. And also the Rag Joint is another wear area. And the power steering valve needs to be 'good' and adjusted properly.
The reason GM used the type of power-over-manual steering they did on a Corvette, vs the typical Saginaw power steering box, is because a manual steering box is inherently more precise and tighter ..by design. A power steering box uses two input shafts, the top stub shaft (where the steering column hooks up) has a small amount of built-in 'slop' which is essentially the fluid control valve. So there will always be a little bit of *designed-in* free-play on the power box, vs a manual steering box. Even a borgeson has a small amount of built-in freeplay. That's how they work. The borgeson tightens the ratio and makes it 'seem' tighter. For normal touring a Saginaw box works just fine. But for track sportiness, the manual is going to be more precise as long as the bearings/bushings & adjustment is all good.
When owners/shops, etc move C3's around w/o using the power steering (engine off, or not running), it puts a huge amount of stress on certain steering components, like the flexible coupler and even the steering box. Try to always move the car 'running' so you don't murder the steering parts..
. Since I do long trips, I wanted parts that could be replaced if something failed while a few hundred miles from home. 
