Does anybody know what the correct/best rear alignent specs are for a 1973 454. I ask this because I almost wrecked my car sometime back in a high speed turn. I had thought the twitchy ill-handling of my car was the fault of the "power assisted steering". I have had everything about the steering replaced/rebuilt, but no change in handling. Then the other day I read an article on Super Chevy on-line where they tested three 1972 Corvettes. A base engine, L-82, and 454. Both small blocks did great but the 454 had bad issues. Testers thought it was 454 engine weight that messed everything up and caused car the under-steer and then over-steer and then back to under-steer...oops over-steer when trying to correct while entering a corner, but found that the rear alignment was off on the 454 car. They didn't say anything about testing the car after re-setting the rear alignment or what the alignment specs were before or after.

 

This is a point of reference

https://www.vansteel.com/PDFs/6382AlignmentSpecs.pdf

 

FWIW, there's somewhat more to sorting a BB C3 for serious high-speed handling than is covered within alignment specs alone or available in off-the-shelf kit form (factory or aftermarket). And, bear in mind when you're turning into sweepers at 100+, you're into RR territory for which typical AX oriented alignment/setups may not be best suited. My $.02

 

I wonder how old the rubber bushings are in your car. IMHO there is too much rubber in the suspension of a C-2, C-3 to have precision handling.Especially when it is old and cracked.

 

i agree with Pop Chevy here as my small block behaved poorly till all rubber was replaced,stock except rear strut bushings,and now is a pleasure to drive.

 

Interesting. What are the effects of the different settings? Why one vs another?

 

Rather than type out what each, caster, camber and toe, do. I'll provide another link that does it for me.

http://www.tirerack.com/tires/tirete...e.jsp?techid=4

 

Let me say that the car has the twitchy steering even at slower speeds but it is not something that can't be easily controlled at 55 to 65 mph. That is why I thought it was/is the "power assisted steering" causing the under-steer/over-steer problem. I know there are conversion kits to change the "power assisted steering" over to more modern "power steering" or even rack and pinion steering. Are the kits meant to fix the under-steer/over-steer problem, or just to update the steering and may be eliminate a lot of leaks? My son has a 1973 small block vette with "power assisted steering" and it feels the same as my car, but I have not driven it like I did my car (same corner at same speed). But at 55 to 65 mph it has the darty under-steer/over-steer issue. I have not driven a C3 in years that didn't have the "power assisted steering" so I can't remember what C3's feel like with manual steering. Just wondering if that is the answer or if there is something to what I read in the Super Chevy article.

 

As a bandaid I would dial some more caster into the car.

 

Cheaper band aid is a smaller steering wheel

 

Mine was like that for a long time. I paid the $100 or so bucks, to have lifetime alignment at my local Firestone Tire dealer and what I did, was take it back and tell them what was going on (same thing as yours) and told them to 'slow' the steering down, as it was darty and unsure at high speeds. They readjusted it and now, it's pretty stable at 85, 90 and even 100 mph. Still grabbing cracks though and I've got to back one more time, to see if they can fix that.

I've got all new suspension front and rear. New rubber on everything, ball joints, sway bar, and the rear suspension and trailing arms were brand new, when I got the car. If your front suspension hasn't been rebuilt completely, your results may vary and I do have the stock power steering.

 

Here is are a few things to think about in addition to alignment specs. What kind of wheels and tires are you running on your 73BB?
Another, has the steering box ever been replaced, like with the Jeep box that some were using for a while? It makes them squirrely to drive.
What suspension mods have been made over the years? Has the ride height been altered front or rear?

I traded my 72 standard Corvette for a new 74, 454 4 spd Corvette. There was a handling difference, like the BB car was kind of ponderous to drive.
After about 6 months a guy offered over list for the car so I sold it to him and bought a new 74 small block 4 spd car. It was much nicer handling and more fun to drive.

Was you 73 equipped with FE7 Gymkhana suspension option and maybe had mismatched parts replaced?

Has the car ever been wrecked hard enough to bend the frame or suspension parts?

Make it right or don't play in the corners for sure.

 

In short order first up is later C4 wheels/50 series tires, or damn similar.....then rack/maybe Borgeson/Jeep steering conversion, junk the OEM system, after that.....springs front/rear, shocks, and the all important cross support between the upper A arms..... OH, plastic rear springs

each improvement is listed in rough order of improvement....

I been at it some 20 years now....this traces my improvements......

 

My 1973 454 Vette is a 40,000 mile car that has never been in a wreck. Front and rear suspensions have been rebuilt, the front by a Chevy dealer just before I bought the car. Shock are good. Steering box I had replaced with a re-built (Lonestar Caliper) unit I got from Volunteer Vette. Power steering control valve is also Lonestar and came from Vol Vette. Wheels are stock 15 X 8 rallies with new BFG TA's (stock sizes). Car was re-aligned. Steering may be a tad better but not right!

The high speed corner I was in could be easily taken at the same speed with any normal car (my '87 Regal Turbo-T would have no problems). I was not pushing the limits. But the speed was enough that the under-steer / over-steer "twitch" was not safe in my Vette.

I have replaced/fixed/repaired enough of the "power assisted steering" to believe that it is not something broken in that system. All work was done by a professional mechanic. But I wonder is it just the design of the system itself. Is that why there are kits to replace it?

I have found a good article on suspensions spec for C3's on the forum, so it may be time to get with the alignment shop and see what can be done.

Thanks for all of the help. I really want to be able to drive this car and feel comfortable doing it.

 

Nothing was ever mentioned about sway bar sizes and bushings, BB vs SB

And how rear alignment/worn components can really affect handling

 

There are a lot of components that can effect the handling of the C2/3 Vette chassi. You need to go over to the Tech/Performance section of the C3 forum and do some searches on the subject. If your Vette has worn components including the IRS differential, it can gretly effect the stability of the chassis.