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Discussion Starter · #1 ·
I'm about to take apart a 56 2dr post for a complete rebuild and want to use C-4 suspension front and rear but have several questions first.

1. If the 84-89 suspension is 62.5 inches wide and the 90-96 suspension is 63.25 wide and the stock rear end is 60 inches wide is there a limited number of rim and tire sizes that will fit using the Corvette suspension parts, or will they have to be modified? Which rear would you recommend or is there a newer year that will work just as nicely?
2. Is it worth it to use the rear transverse spring or upgrade to coil overs?
3. Have you found a reliable source for the suspension parts or is e-bay the best source? The prices seem to vary widely.
4. Using a 700R4 transmission and a 28 inch tire what rear gear ratio do you recommend?

The last car I did had a Jag rear and it was a piece of cake to install, the rear looks pretty straight forward, but the front looks like more work. What the heck it's a hobby time is not the impostant thing.... right?
 

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Hey dawg welcome to the site.
1. I went with the later c4 thinking it might be a little more advanced engineering, don't really know if it is. With the early you can run deeper dish rims, more old school look. The later you use the modern Corvette style. C5 require major mods.

2. I went with transverse the way GM designed it.

3. Local is IMO the best way to get parts. In my area you can find c4s cheap.
4.I like to shift, 6 speed for me.
Jim
 

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sawdawg, look up chevynut one of the members here on this site, he has all the answers for a c4 conversion. He's building one for me.
 

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sawdawg, welcome to the site!

We build complete chassis for the tri-fives and also do stock frame conversions that lets you bolt in the C-4 suspension front and rear.
like Jim said GM used the transverse leaf, if there was a better way it would have been on the car.

give us a call, we have allot of experience with these setups and allot of helper parts for getting them together and on the road.

http://www.newmancarcreations.com/55-57-chevy/
 

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I'm about to take apart a 56 2dr post for a complete rebuild and want to use C-4 suspension front and rear but have several questions first.

1. If the 84-89 suspension is 62.5 inches wide and the 90-96 suspension is 63.25 wide and the stock rear end is 60 inches wide is there a limited number of rim and tire sizes that will fit using the Corvette suspension parts, or will they have to be modified? Which rear would you recommend or is there a newer year that will work just as nicely?
2. Is it worth it to use the rear transverse spring or upgrade to coil overs?
3. Have you found a reliable source for the suspension parts or is e-bay the best source? The prices seem to vary widely.
4. Using a 700R4 transmission and a 28 inch tire what rear gear ratio do you recommend?

The last car I did had a Jag rear and it was a piece of cake to install, the rear looks pretty straight forward, but the front looks like more work. What the heck it's a hobby time is not the impostant thing.... right?


Welcome aboard sawdog! C4 is certainly a great and worthwhile modification. I guess, regarding which year to purchase just remember, wheel back spacing can take care of some issues and, the rear can be narrowed. My preference is the later C4.

Transverse spring will give you a decent ride, however, My preference is Coil Over Shocks. They will give more adjustability (adjustable) and you can vary the springs to compensate for any conditions you may impose upon the chassis/car.

As far as a reliable source, local certainly will do two things – allow you to see the parts prior to purchase and save freight. I have had both good and bad luck with purchasing components through Ebay, but then that is entirely dependent on the provider you choose.

A 700R4 has an OD Final of .7, so it really depends on other items, i.e. what RPM do you want at say 70 MPH and does this fall into the efficiency range of the engine you will use.

I will say this however; one does need a chassis jig to keep it right. I built mine years ago and would not attempt to do it otherwise.
 

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I'm about to take apart a 56 2dr post for a complete rebuild and want to use C-4 suspension front and rear but have several questions first.

1. If the 84-89 suspension is 62.5 inches wide and the 90-96 suspension is 63.25 wide and the stock rear end is 60 inches wide is there a limited number of rim and tire sizes that will fit using the Corvette suspension parts, or will they have to be modified? Which rear would you recommend or is there a newer year that will work just as nicely?.
Per my measurements the late C4 (88-96) is 63" wide and the early ones (84-87) are 62" wide with brake rotors installed. The front ends are 61" early and 62" late, with discs. The difference is only 1/2" per side and can normally be accommodated with wheel offset. Here is a car that I built a chassis for that uses an early C4 rear and a late C4 front end.

http://www.wadesgarage.com/gallery/main.php?g2_itemId=2055
http://www.wadesgarage.com/gallery/main.php?g2_itemId=3522

The tires on this car are 275 in the rear and 245 in the front.

There are wheels out there that will work with either suspension, and you don't have to use Corvette wheels. Many custom-offset wheels should work fine.


2. Is it worth it to use the rear transverse spring or upgrade to coil overs?
As mentioned, the stock transverse springs will work but if the car doesn't sit at the correct height, you have limited adjustability, especially in the front. And it's a real PITA to shim the front spring. Also you have limited spring rates to choose from, and the aftermarket adjustable height spring is costly. I have used coilovers on my own car, and most of the other chassis I have built were for coilovers by the customer' choice. They give you more flexibility in height adjustment and in spring rate choices. Personally I think coilovers are an upgrade....corvette owners consider them an upgrade too. They do add around $900 or so to the cost of the build.

While I think the plastic springs can be made to work okay, I personally think GM didn't use coilovers in their design because they're more expensive than the plastic springs. Look at what's under most of the exotic cars and you'll find coilovers.

3. Have you found a reliable source for the suspension parts or is e-bay the best source? The prices seem to vary widely.
I have bought several on eBay, but the shipping charges can significantly increase the cost. Look locally first.

4. Using a 700R4 transmission and a 28 inch tire what rear gear ratio do you recommend?
You are fairly limited on stock gear ratios. The Dana 36 only came in 3.08 or ratios lower numerically. The Dana 44 was 3.08 in the early cars, and 3.33, 3.45, and 3.54 in the later years.

The last car I did had a Jag rear and it was a piece of cake to install, the rear looks pretty straight forward, but the front looks like more work.
I have found that the rear is about 1/4 of the work and the front about 3/4 of the work, based on my design and experience building several frames.
 

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Discussion Starter · #7 ·
c-4 project

Thanks for the information, I know it's quite a project but I have a lot of time especially with winter coming. It's hard to fish or golf with ice on your nose.
I have a frame table left over from my Bonnevill Streamliner project. It will have to be widened a bit since that car is 23 feet long and 22 inches wide. I think the modification shouldn't be too much of a problem some channel iron and a bit of welding. I guess my first worry is that the suspension will be too wide for the car but I think not if so many of you are doing it. My last street rod/shop truck is a 40 Ford pickup with a jag rear and a mustang ll rear I think I can do it, I really like the idea of the corvette ride.
Today I widened one of the rear wheel tubs to make way for the bigger tires, it's been a while since I mig welded as I prefer tig welding but there was no way I could contort my body into such a small hole and weld.
Thanks for your help
 
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