cjsdad

Has anyone ever put a Corvette IRS in a 67 Cutlass? I have a chance at a DANA 36 out of an 85 Corvette for a good price that would be cool-as-hell under the back end of my car. Obviously not as robust as the DANA 44 but I'm not building a dragster. Just a cruiser. I have read about Camaros getting the IRS treatment and is said to make street manners a lot better.

The track width is only 1/2 inch different and the curb weight of both cars is almost the same as well. Building the mounts would be interesting and maybe even fun. I figure since I am gathering parts for my build, now would be a good time to get the IRS. Comments? Suggestions?

joe_padavano

There are aftermarket rear frame rail kits to install IRS in A-body cars. Frankly, unless you are swapping to a high dollar custom chassis with all Corvette suspension, this is waaaay more cost and effort than it is worth. keep in mind that besides the chassis mods, you need to mod the floor pan, re-route the exhaust, likely modify the gas tank, re-route all the lines, build a new driveshaft, change the e-brakes, etc, etc. You aren't really going to see all this work under a full-body car anyway. Spend the money on a quality suspension rebuild, good shocks, and a decent rear sway bar. Buy a repro W-27 cover for bling.

cjsdad

Well I've put my foot in the deep end this time. In spite of Joe's excellent advice i have purchased an independent rear suspension out of a 1990 Corvette to install in my '67 Cutlass. I know it sounds like a lot of work but for the amazingly small price of $300 I get limited slip diff, disc brakes, and IRS. A complete setup like that on my existing diff housing could cost three times that even with used parts. So, with that small explanation out of the way, here is the good stuff.

Rear_zpslp0wolyq.jpg

Front_zpsjfx7ynoc.jpg

cjsdad

RonFX was kind enough to send me a copy of some documentation with the frame dimensions for a 1966 Cutlass which should be the same as a '67.

Frame%20Dimensions_zpsrshffoec.jpg

cjsdad

Here are some dimensions for the differential from something I found on the web as well as some of my own measurements. In oversimplified terms, I simply need to fashion some mounts for the new diff mounting points and bolt it in. I'm sure it will take a lot of trial fitting to get it positioned correctly but it should be a blast to drive when finished.

c4rear_3_zpszx8qdmkk.jpg

Drawings_zpss3sxjgsn.jpg

cjsdad

It looks like the upper mounts will be able to be positioned at or very near the spring mount locations on the frame. I will then need to make some mounting rails for the front control arms in the arch portion of the frame as well.

More suggestions or comments?

oldcutlass

Its easier if you use a C channel and fabricate brackets to it. I mated a late model front and rear suspension to a 66 Vette. You will have to mod the floor as Joe Said and do something with the fuel tank. Make sure everything is square.

cjsdad

The C channel will work well for making pockets to locate the upper mounts but I will have to make pockets for the round mounts too. Not sure how I will control the front of the diff housing though. I didn't get the factory c channel that goes from the pinion mount to the trans. I don't know if the aluminum c-channel can be found or even if it can be modified to work with a 2004r. But I'm gonna find out.

oldcutlass

For the front of the diff, I used plate with a vertical gusset from the C channel. You can shim as required to maintain proper pinion angle.