C4 guys, tell me I'm crazy
 

I'm gonna dust off my 93 and start working on it again. It's going to be slow progress as money is tight. My plan is to do a budget LS swap, TH400 (yes I know I have to fab a crossmember), small turbo. Here's where you're going to call me crazy.

I'm going to keep the IRS. My car is originally an auto so it's a D36. We know that won't live. My plan is to swap in a Ford 8.8 IRS center section and fab a way to make it fit. Next I'm going to have to find a way to mount a larger spline outer axle. Not sure if having the hub resplined or adapting another hub to the spindle will be the way to go. It's an ambitious project, but I think it's the best way to keep the IRS and make it solid enough to go mid-low 9's.

You're crazy!!!!!!

That said, I'm always a big fan of going against the grain and figuring out a way to make it work.

Best of success to you with your project and goals.

Best of luck with the project, buddy...nice to see you get back in the game...woot!....

Thanks guys. This will be a slow moving project, as time/funds allow. I'll keep everyone posted.

what indication do you have that the 8.8 inch Ford is any stronger than the stock ready bolt in C4 Dana 44 set up? Looking at their specs /dimensions they seem to be quite similar in size and capacity.

Save yourself some time, money and heart ache and put a solid rear in it now. No way an IRS will hold up with that HP. I had some real good D44 in my car with only 375 RWHP and I broke everything. Unless there some reason your required to run the IRS I would do it right the first time and save some money in the long run. Been there!

I disagree Mackey - to a certain extent.

Absolutely a solid axle 9" will be stronger than an IRS setup. But, a properly built IRS will hold up to a lot of power.

While this thread is old, and we have no idea if the OP is still working on this project, a good discussion can still be helpful to anyone searching for answers.

Contact Dutchman Axles.


https://cimg5.ibsrv.net/gimg/www.cor...b21c970d82.jpg

This is a 9" IRS they offer with Willwood brakes. They build custom axles to go with it as well.

People use this type setup to convert many different styles of cars to IRS. As well as trophy trucks for off road racing.

Dutchman makes some real nice stuff but a bare housing is $1,250. Buy the time you dress it with good parts, we are taking big money.

Was that with an auto or manual transmission?

I would also vote for 9" rear over IRS. In the long run it will yield you less headaches overall. Bolt in kits are available. Below is from Carrols web site:

C-4 Bolt in Straight Axle Conversion

A true 4-Link rear suspension designed to be installed in a few hours with 9 simple bolts. Our kit uses all 4130 Chromoly brackets CNC cut in house and TIG welded in our own fixtures to ensure accuracy and repeatability. 4-Links include 3 piece Chromoly rod-ends, 4130 Chromoly tubes and utilize the same high strength tube inserts used on 2500 hp Pro-Mod cars, not threaded tubing. All housings come with a jack bar and wheelie bar mounts standard. Furnished with all necessary Grade 8 hardware assembled & ready to install. Kits are offered in several packages to meet your specific performance level.
Level I Package $3995.00

Complete Chromoly 4-Link System
GM 10 Bolt housing upgraded with 3”x.250” wall axle tubes
LPW Aluminum differential support cover
Spool with your choice of gear ratio
Strange 33 Spline axles
Strange Single adjustable coilover shocks
Assembled & ready to ship**
Level II Package $4995.00
Complete Chromoly 4-Link System
Strange 12 Bolt Housing, Chrome-Moly caps, 1350 yoke
Strange Aluminum differential support cover
Strange Spool with your choice of gear ratio
Strange 33 Spline axles
Strange Double adjustable coilover shocks
Assembled & ready to ship**

I worked with Leo and developed these packages for my C4. It's a simple bolt in swap using the factory attachment points. I ran 9.4 @141 in my car with zero failure. Over the years I spent over twice the cost of the solid axle kit in IRS parts with at that time under 400 RWHP. For me it just made sense!