I'm trying to decide what to do with the front suspension of my 79. I'm going to be installing an early (narrow) C4 rear suspension to get rid of toe change issues. I'm currently having the frame stripped, then I'll seam weld it and install either a 4 or 6 point roll bar.

The car is currently stock and my original plan was to do a steering rack conversion and spherical bearings in the control arms. However, I'm also tossing the idea around of just hacking the C3 front suspension off and grafting in an early (narrow) C4 suspension. I have all the equipment to do either, but obviously the C4 is considerably more work. The car isn't going to be a "race car" but everything I read about the C4 front suspension is lightyears ahead of the C3 as far as ride. I've settled on a big block/t56 swap and I'm trying to build a really good/fun driving road car. Unfortunately, I don't have $35K to just buy an aftermarket frame, and $2K for aftermarket front a-arms just isn't reasonable in my book (or with my budget) as I can buy a whole rolling C4 frame for around $500.

So, considering that it's not a "race car", is the difference in performance and/or ride between the C3 and C4 front suspension (assuming they are both running a steering rack and good solid bushing) really that significant?

 

I have a 2 door 57 Chevy 150 that bought an 84 C4 rolling body and frame that I got for the suspension. I removed the engine cradle and had a custom front frame clip made. The price was about $2,000 but I parted out the C4 body parts and seats and was able to pay for the entire fabrication work. I then has a shop cut the original frame cut and the new fabricated clip grafted in. The width of a C4 frame rails and a 57 Chevy frame rails are very close and with the engine cradle being a bolt in on the C4 makes the fabrication easier. I have no idea of the width of the C3 rails are compared to the C4 but would be worth looking into. The A-arms and rack and pinion all bolt up to the engine cradle.

 

Not sure what your plans may be for this project, but I just put a flaming river rack and pinion in my 78 and it was one of the easist things I have done. Rip ALL of the steering components out of the car. The cradle they supply bolts right in to where the steering box and idler arm used to be. No drilling, no welding. Then all you do is install the steering shaft/ujoints from the steering column to the rack itself. It all comes in one kit for a C3 corvette. Then hook up the 2 hoses. No engineering, no guess work. I am very happy with the results. Just my $.02 for your consideration.

 

Flaming river would definitely be an easier option and likely cheaper in the end. If this is not going to be a race car what is the reason for the roll bar?

 

[QUOTE=80-Vette;1602498970If this is not going to be a race car what is the reason for the roll bar?[/QUOTE]

Frame stiffness.

 

The guys at Ridetech told me that bump steer will a problem when installing a rack in pinion with our stock frame. I wanted to use their strong arms with a modern rack.

 

I've seen that mentioned, but a good bump steer kit should cure any bump steer. There's plenty of people running rack conversions without bump steer issues.

 

Two very different solutions!

If you are looking for a completely different suspension, than yes, the C4 suspension design is much better....BUT lots more work. Personally if you are looking for a C4 suspension, you are much better off just sourcing a C4 car. A buddy of mine just found a 96 LT-4 C4 6 speed (330 HP) red, very good condition relative low mileage car witn about 45,000 miles on it for less than $10K. It is a great C4 car for him to develop into a fine machine.

As for steering, I would forget R&P for a borgeson steering box..it will give you 95% of the preciseness of the R&P with a super quick steering ratio of 12:1 and no lock to lock issues using a R&P for less money.

A solid C3 rear suspension with composite spring, like new axle shafts/rear diff, Bilstein Shocks competition heim jointed struts ius pretty tough to beat on the street for a C3 AND will ride much better than the C4. C4's ride very stiff and are not great riding for the street...just saying..my car below:

From previous posts:


I have a 78 L-82 4 speed car with the gymkhana sport suspension (67,000 miles) that I have owned for 34 years and I have tinkered with the suspension one part at a time over all those years to achieve the perfect balance of superb handling, steering response and a firm but not harsh ride. Not knowing if you have a base suspension (most likely since most did not have the sport suspension from the factory) or the sport suspension, below is what you need for truly sportscar handling with a great ride for your 78:

Front:

550 lbs front coil springs/1 inch lower than stock-$100
1 1/8 inch solid front sway bar (OEM Bar size)-$200
poly upper and lower control arm bushings-$50
Bilstein HD shocks-$150
Front Spreader Bar-$100
Custom blueprinted/rebuilt OEM steering box- GTR 1999-Gary Ramadei-$300
This modification will make your OEM box about as good as it gets with the OEM steering and very close to a borgeson.....not quite but close
Rear:

360 monospring-$300
Bilstein Sport shocks-$150
OEM Style Rear Sway bar (not the aftermarket type bars. I highly discourage NON OEM/GM style rear sway bars)-7/16 or 9/16 or 3/4 inch (I have this one replacing the stock 7/16 inch bar)-$200
Competition adjustable strut rods with heim joint ends-$200

Total Cost $1750

This suspension will get you a FAR SUPERIOR suspension than what came on the car when it was new, X3 if the car had a base suspension from the factory. You will need to add 17/18 inch rims and tires (ZR rated only W/Y sub rating) later to maximize the superior suspension setup. I have ultra high performance summer only tires Front-255/45/17 ZR and rears 255/50/17 ZR's.

In my Opinion, you need a rear bar of some size, especially if you want balanced handling with a C3.

My 78 above is far superior to any stock handling C3 BY FAR. Does it handle like my 10C6Z06? NO! It will smoke just about any stock lightly modified C3 in the curves..no contest.....and no Stock SBC C3 of any year or engine designation can even come close to the rebuilt/upgraded 355 L-82.

Last edited by jb78L-82; 11-11-2020 at 12:54 PM.
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As for rear camber issues on the stock C3,

 

Thanks jb, that's good insight. I'm certainly not looking for a C4 (never wanted one and wouldn't have one) and that's not the goal. I don't know what the suspension is on my 79, but I'm going to assume its the base suspension and it's worn out regardless. Are you running a manual or power assisted box?

 

Custom Blue printed and rebuilt OEM Steering box by Gary Ramadei...forum member, GTR 1999, as described in previous post....in bold print ^^^^^^^^

 

Yeah, I read that. What I was asking is are you running it as a manual box or do you have power assist (with the factory ram and hydraulic actuator)?

 

Power..OEM setup