I.R.S. choices
 

I'm trying to school myself on which I.R.S. is best for my '39 Chevy. There is SOME info on the different setups but seems to be nothing on narrowing a unit. The new Jag looks good and air bags would slip in where the coils are now but the gears seem all wrong. Ford Expedition is 67" wide and can't even find a picture to see if it can be narrowed. The new Mustang (2015 -) would be nice to but gears are a problem. I only have 7" from the back of my 8.8 now to the gas tank and would like to keep the stock tank. Also would like to use air bags in place of coils which sorta rules out 'Vettes. Anyone narrowed or installed an I.R.S. unit that can shed light on this subject. Thanks.

Have you looked at Heidt's IRS setup? I don't know which widths it is available in, but I bet a call to them will answer that.

Heidt's would be grand BUT at $10,000 plus it's not an option.

Understood. Just thought I would throw that in there. I also didn't know they were so proud of their stuff! Sorry about that!

Looking more for info on narrowing a unit such as an Expedition or T'Bird, etc.

Don't they narrow the Ford 8.8 IRS to put in the Miata's, don't know about bagging them tho, you could check some of the Miata build threads.

Any chance a gto rear would fit without narrowing?

Gen5 rears bound to be cheap and strong ?

GTO uses an A arm that is canted in such a way they can't be narrowed. Had one local for a good price but just would not lend itself to my application. Frustrating.

I have heard about the Miata and trying to research it a bit.

Gen 5 Camaro?

What width do you need? I'm using an E36 chassis BMW IRS in my project. The stock width I measured from outsid of the tires with stock BMW wheels is 63 1/2". Haven't measured from flange to flange as I haven't removed it from the donor yet.

Why would that rule out the corvette IRS? They have been used in every type of vehicle including pickup trucks. Here's a link that might be helpful. I don't see why you couldn't use a shockwave air setup in place of the coil overs on these.

http://flatout-engineering.com/produ...tallation-kit/

True, dozens of BMW options, or even from 4wd Audi's or VW cars. Subaru or various rwd Jap stuff.

The C4 'Vette has some odd gears with the most popular being 2.73, then 3.06. I'm sure I could replace the composite leaf with a set of air bags. Looking at the Expedition (late model) with 331 gears. Would have to narrow it and build mounting points but that is true of just about all the I.R.S. out there. The off shore stuff (minus Jag) comes with unknown gears and maybe no options for replacement gears. Not sure about how strong they would be. Can' find pictures of just about any of the systems.

What about something like this? 3.42 gearing, huge diff.... plus 7 speed manual trans...
https://www.corvetteforum.com/forums...post1599417952

The gears are right BUUUUT there are a few other problems that it would cause. First is the $3500, then the back seat issue. It would take up just about the whole back seat except for maybe a single cheeked person. Upgrade the engine from an LM4 to a gen V too...not a bad idea. LOL

You can run a Gen3/4 engine with a C5/6 torque tube and driveshaft and have a 7 speed manual :)

https://cimg6.ibsrv.net/gimg/ls1tech...cf769e6f82.jpg
Nope, already have a headache LOL. Sprung for a late model Expedition which does not have a cradle and can't find any pictures of the naked rear end so it's feel my way thru this project. Intend to take pics and document just hope it's not a failure. I think the best way to go is build a back half on the bench then scab it into the car. Thinking of using pre-bent rails this time.

I.r.s.
 

Got a package today, larger than I though it should be. This is an I.R.S. from a 2010 Expedition and it's big and heavy. I'll need to narrow it about 8 inches but how I'm not sure yet. Need to mock it up on the table, then cut. TBC....
https://cimg1.ibsrv.net/gimg/ls1tech...7a10d23682.jpg
https://cimg8.ibsrv.net/gimg/ls1tech...2251b98fb8.jpg

I.r.s.
 

Broke down what I could and here are the axles, brakes and center section. This stuff is large and I'll be looking into trying to adapt a smaller disc rather than go to a bigger wheel. The Expedition weighs twice what my '39 does so I really don't need the extra braking power. As I start to build I'll post a few pictures.
https://cimg2.ibsrv.net/gimg/ls1tech...cab01a9094.jpg
https://cimg7.ibsrv.net/gimg/ls1tech...4249787f5b.jpg

Wouldn't an Explorer have been better suited than an Expedition?