I like your setup OCB!
For a street car it should be good.
Even on normal twisty road driving I rarely went to 50% of the cornering speed the car was capable of.
Does that sound about right?
If you think you are going to track it, or autocross it, or slide it thru corners on the street, then I might suggest a couple changes.
But otherwise not.

Your biggest "suspension" issue is going to be your right foot! LOL
Whether or not you are going to like your rear sway bar choice will depend on how much of that 600ft-lbs you try to use in a corner, and how soon. Under lighter throttle it should be fine. You may just have to wait until the car is straight before you unleash the "monster" up front!

Enjoying a cruise is all about balancing crisp steering response vs ride quality. You have a good spring/bar package. So the rest of the ride-vs-handling quality "balance" will be left up to the shock tuning. I am glad you got the QA-1 adjustables vs the one-setting Bilsteins. See how the "wallow" is on single or double wheeled bumps. Tighten them up a click or two at a time until it goes away. If too "tight" it will start to skip on that same bump.

I hate to disagree with Van Steel, but getting rid of the bump steer makes the car so much more enjoyable to drive, on anything with bumps, even on the street at normal speeds. You can always add that later. Take the car over a small bump in a corner, Hold the steering with two fingers. If the wheel moves, it has bump steer. If it has no bump steer, the wheel will not even move as the suspension goes up & down. If it bothers you, do something about it. It will require some custom adjusting to the height. Now good luck getting a regular alignment shop to do that. You will either have to do it yourself, or go to a real race shop.

A bump steer kit, since it bolts together, would have to be checked on a regular basis for tightness, for obvious safety reasons. That could easily get forgotten by a regular customer, on a street car, and if it comes loose, that could be disastoriously dangerous. Me I will probably go as far as safety wiring mine, if possible. They do include "double locking nuts". You will have to check the heim-jointed strut rods for tightness periodically also.

We just had a customer bring his gorgeous, but wrecked, 65, by the Corvette Shop. His real knock off wheel spinner came off the front wheel while he was driving down the road. You are supposed to check these "knock-off" spinners for tightness very regularly. He admitted he has never checked his. Errrr....

 

OCB: can't find your original text but I would have real issues with a non-motion compliant rear anti-sway bar setup that didn't adhere to the factory original. Clamping to the rear of the trailing arm is a cheezy way to just get by with something that sort of works. There were many threads on this subject a while ago. My experience was the clamp work-hardened the trailing arm until it just snapped off. Cost me some $$$$.

Oh and you haven't mentioned your alignment settings. I have very aggressive autocross settings which make the car very annoying to drive normally. I suppose you need to wait and see what you like but I would start out very conservatively.

Have to agree here with Leigh on the bump steer question.

 

I talked with Eric at Van Steel twice about their bump steer kit.
He said he has it on one of his street cars and was planning to remove it.
It was some time ago and I don’t recall the exact reasoning, but he suggested that on my suspension set up and how I planned to use my car on the street, he didn’t think it was necessary, overkill and a waste of money.
He told me he would sell it to me if I really wanted it.

Chris Springer Restoration who is doing the body and paint on my car, has a full suspension and alignment rack in his shop.
Chris will be doing a “close” alignment before the car leaves his shop.
It will be close enough to complete the build, put on a few miles and let the suspension settle.
After I complete the build the car will go back to Chris and he will do the full alignment and set up the suspension.
He had his C2 vintage race car up on the rack tweaking everything for Monterey Car Week where he was invited to race and display his C2 car.
It was really cool to see everything he has done with that car.

I seriously doubt I’ll need the bump steer kit, but if I do, I can always swap it in later.

 

I had my '72 aligned last week and asked for as much caster as possible. What I gave them was a request for 0" toe, -1/2° camber, and a minimum of +2.75° caster.
I knew toe would be starting way out because I had restored all of the under-car linkage. Here's how it was returned to me:


Can anyone provide an opinion on how the car should feel at 55mph with the after-alignment settings? (brand new BFG 225/70r15) I'm not giving my opinion on how I think it drives because I may have other issues going on.

I'm not thrilled with the caster (2° & 1.3°) just from the reading here on the forum. If I were to use this as a starting point, what effect on toe and camber would a move of A-arm shims from front to rear be? Is there a rough guideline for the amount of caster change for a specific shim thickness?

I'm open to all suggestions except for changing components away from stock. That said, I've got poly a-arm bushings I put in a loooong time ago that appear to be fine.
Thanks!

 

That'll be twitchy, and probably pretty scary at 55 mph. Does it feel like you are riding down the road while balancing on a rail under your car?

What's wrong with non-stock components that bolt on? Just keep the old trash for the next guy to throw away*. Other than heim-jointed strut rods, the SPC adjustable UCAs are the best suspension mod I've done. They eliminate the need for shims.

*I just recycled a second set of front control arms that had been haunting my storage space for 5 years. The aftermarket replacements are much better, adjustable, and semi coil-over ready.

 

On that alignment I would say that they didn't try very hard. I recently bought 4 new tires and had my Q5 Audi aligned. I was in a hurry when I picked it up later for $1800. At home I looked at a similar alignment print out and was pissed when some of the numbers which were out of bounds on the before were unchanged on the after for a 4 wheel alignment. I took it back the next day and talked to the manager. I left with a perfect side to side numbers and all good looking.

You need to do the same thing. Side to side equal is very important. I've heard the old BS that they did that for allow for the crown on the road. We know that you turn both left and right and want the car to do each direction equally . Well you ask for easy to do specific numbers and didn't get them.

Stock c-3 upper a-arm cross bars were made to have a max adjustment of @ 4.75 dregrees. I've done it. Time, ware, and sagging can limit the adjustments. But any competent alignment person grabs each tire to feel or see slop like in the wheel bearings and arm bushings. A friend came over after an alignment and they said they couldn't do it because of too much in and out movement on the rear yokes. So we pulled his differential out at my house and he took it to a shop

 

You should show these to your your alignment shop.
Tell them to meet the street specs.
You need at least 3* pos caster, 4* if they can get it.
And even side to side.
They have 1/4" toe-in in front, and much less than that at the rear.
The front one means too much tire wear, the rear one means twitchy handling on a C3 chassis.
You need 1/8" toe-in in back, period, no other number. A fraction over if necessary, but not under that at all.
It is that important.
Yours is only .03" just way too low.
Yes it is a pain to adjust, but that is the main thing that needs to be done.
Take them a pack of rear alignment shims from a vette vendor.
The front one can be near zero.
Camber is way less important on a street car. It can be zero. That's actually better for tire wear if you drive gently. Up to 0.5* neg camber is ok on the street, OK if you like to push the corners. You do not need any more on the street.
The 55 year old factory specs are useless, they were meant for Bias ply tires, not radials.

Most machines read out in degrees toe-in these days, and the above specs are in inches.
Converted:
1/32" total front toe-in = 0.067 degrees
1/8" total rear toe-in = 0.27 degrees

 

.3* total toe would be good.
But his has another zero there.
His is .06* total toe - that is way too low.
And they didn't even try to change it before & after.

 

Regarding the Van Steel settings, what is "rake"?

Thanks everyone. I guess I'll have to revisit the shop to discuss it - that's what I suspected my next step was but wanted feedback from folks way more experienced than I.

I should have said they didn't touch the rear alignment as it more than likely needs a change out of the T/A and control rod bushings. I just wanted to see where it sat until I tackle that job.

The specs I gave them were a slight mix from past threads from the Vette Brakes settings:

 

Rake has very minimal effect on alignment. The higher you lift from OEM height in the rear the more the rear axle will shift to the right in relation to the frame rails. The higher you lift the front from OEM height the further your caster/camber will be off WITHOUT getting another alignment.

If the rear is taller (more distant from the ground) there is said to be a positive rake. If the front is taller there is negative rake, which is seldom if ever ...

 

I see, so it's referencing whole-car rake angle not a setting for the front alignment.

 

Correct. This comes into play for high speed handling. These cars need a bit of rake. But is not a component of the front alignment settings.
And I think your current settings are dismal as well.

 

Reading through all of this I realised that I didn't mention my front spreader bar earlier on when I put up my spec's.
Finally had a chance to take mine out for a really aggressive street drive today. I live right on the edge of the Hinterland here in the Sunshine Coast area of Queensland Australia. A semi mountainous area full of every type of turn from super tight realitivly low speed hairpins to series of ongoing S turns, sweepers, all up and down hills, some of it fairly steep. Great place to play in other words.
So, with rear wheels right on .4 degrees camber. Front right on .5 degrees camber and my new heim jointed strut rods. I'm happy to report I'm very happy with the street manors of my car. Front sticks good and car feels neutral under light to med power in the turns. Just a little understeer in a downhill coast through a tight turn but not at all bad. Just a little power into her and she really plants well.
Wide open through the turns isn't something I'm asking her to do so I can't comment.

 

That comment I put in red tells me you have a very nicely balanced setup for a street car.

And also your earlier comment that it tracks very nicely on the highway, ie: it's not nervous.

The wide open throttle part.... that's called fish-tailing where I come from!

 

I for one always questioned the need for a spreader bar if you already had the following items. Completetly stitch welded frame rails, Chevy power book frame gussets, and solid motor mounts. So I had years of 100's upon 100's of lap times with notes and I bought the VB&P speader bar kit in the early 2000's. I couldn't see a verifiable change in lap times at differnet tracks. True testing would have required showing up early on a test and tune day and try and lay down three laps within a .2 second window and then install the spreader bar and see if a change in time occurred. I put it on like over the winter.

Now on a flexy flyier stock old frame with upgraded springs etc... It might really stiffen up the front end. It's very common mod for all the unibody cars that you see at the track.

Really old picture of my 396 stroker SBC with spreader bar.



Installing my 3-4 fourth rebuild 434 in 2023. I added my dreamed up water cooling system and changed cam timing.

 

Very good data point on the spreader bar!

 

Well I'll add this to the spreader bar discussion.
I don't have a completely stich welded frame with all the gussets. I have a old, original somewhat rusted frame.
I have frequently told others that "bang for the buck" the spreader bar is absolutely the best mod I have ever done to my car! For so little money it made such a noticeable improvement to the handling of my car.
really, really noticeable improvement in S turn situations where you quickly swing from right to left to right again kind of thing.
So, for the Vast Majority of us with street cars that for whatever reason, don't have the ability or inclination to strip our frame, clean, weld, gusset and reassemble our entire car. (Kinda a big job for most of us).
The spreader bar really does help stiffen up the stock flexy frame.
I don't have any track times. No data to prove it.
I drove my car before the spreader bar installation. Pushed it hard through some S turns near my home, went home, put the car up and installed the bar. Did a quick camber check and took it back through the same S turns later in the day. I was impressed. And I still am. And I can actually make minor camber adjustments by cranking on the spreader bar.

 

That is what I said. The spreader bar works very well. All the modern unibody cars add one from tower to strut tower

 

I wonder if solid engine mounts add any measurable rigidity.

I have a stock frame (which has slightly thinner wall thickness, starting in 80), but I had made a bunch of other changes at the same time, so I don't really know if the strut brace does anything. It looks nice, though.

 

I would assume solid motor mounts would help significantly as well.
The a-arm mounts are roughly 12" higher than the engine crossmember below the crank balancer, so with tire loads that area will flex that area unless supported. Sideways tire loads can hit 1000#, and the upper a-arm mount is going to have to absorb part of that. So it clould easily flex some, affecting the alignment, both the camber and toe-in.
It is just a big "C" shape, turned 90*, with the open part pointing upwards, and the a-arms are pressing on the ends of the C.
Someone has published a go-pro video of this a-arm "shake" Interpon? or Ignatz? IIRC they did it with a loose spreader bar.

Both the spreader bar, and the solid motor mounts, do the same thing, they complete the top section of that large c shape, and completely box it out, and go direct from a-arm to a-arm.
Adding one of those items should help tremendously, by boxing in the top of the "C".
Now once you have one of them, adding the second one may not help that much more.
Once the box is stiff, how can making it stiffer help much more?

That would account for both Gkulls and 4-vettes observations.