Independent rear suspension

[EarlsflyinCobra]

My kits rear end is based on a 79 to 93 Fox Body. I have been told that there is a Ford independent rear suspension that will bolt right in as a replacement for the Fox body rear. Is this the case and if so what rear end do I need to look for??

Thanks, Earl

[Tim Brewer]

Could be the IRS from a T Bird....

[ffindling]

There's an IRS assembly for '94 and up cars that bolts to the same
pickup points as the solid rear assembly does.

....Fred

[map]

Check here...
Fasterpatricks Custom Cobra

[nevermind65]

http://www.mouthbreather.net/IRSSWAP.HTML

[cycleguy55]

Has anyone ever thought about or tried using a completed IRS & sub-frame assembly from an Infiniti G35? There's a lot of aluminum in those to reduce unsprung weight, and there are getting to be more of them in wrecking yards. LSDs only came standard in Sport models, but are available for the open differentials, though they seem to an atrocious price (e.g. $1400+).

[Ralphy]

Is the IRS a multi link design, or is it a double wishbone? Multi link would be a bit complicated to set up. Plus limited slips, limited supply as you said.

Ralphy

[Tom Wells]

Earl,

What nevermind65 said...

I have done that to the Zephyr. It's great! First Coast Cobra Club • View topic - Zephyr dirty hands party Saturday 1-24-09

If the pickup points for the present rear are identical to the Mustang's, you're most of the way there; the Mustang IRS also uses the quad shock mounting points, so if those aren't present you'll need to figure out how to add them to the chassis. Also, the rear u-joint is different so that will need to change, but that's pretty easy...

The '99-'04 Mustang IRS was made to "bolt right in" to any Fox Mustang. Yeah, right...

BTW if you decide to do this swap, the '03-'04 differentials and axles are 31 spline, compared with the '99-'02's 28 spline.

Have fun!

Tom

[Luce]

I took matters into my own hands...

Lonestar Classics Forums • View topic - I'm in! LS 427 with home brew IRS

[strictlypersonl]

There are many IRS designs in late-model cars that would work - assuming you don't care where your wheels come out relative to the body. The problem is that you want a design that has a ~53.5" hub-to-hub distance in order to use original-offset wheels. Most newer IRS designs will exceed that by more than 5" so you're stuck with weird wheels or having them stick way out from the body. Factory Five's system uses custom arms and half-shafts in order to bring the wheels under the body.

[LMH]

Hurricane and FFR both build IRS units that are an assembly by themselves. Track width would be more inline with our type of cars. You could look into adapting either into an exsisting chassis.
Larry

[ERA2076]

ERA Sells a couple

Gen 1




Gen II




I have an 03 Mustang Cobra and have had the IRS out of the car. It is a monster compared to a Cobra roadster


Pillaged photo - 99-04 Cobra




An ERA is going to fit - IMO Fords system would be misapplied (I think a T56 in a roadster is misapplied also so take it with a grain).

I have the cradle, control arms, uprights, anti roll bar, and brakes for a Gen 1 that came out of my FIA. Six pin hubs and wheels also.

You would need to supply the XJ6 differential and shocks (ERA has assembly instructions) and of course location and attachment to your chassis.

chr

[Rog246]

Hey guys, us blokes building Harrison Cobra's in Australia use Nissan Skyline R32 & R33 complete rear IRS subframes and they work a treat. They use the same bolt pattern as Ford and are as stong as. There are also heaps of adjustable suspension parts available for these. Nissan has a reputation in the market for building the strongest drive trains out there. On top of that there are a multitube of diff ratios available asa wellas several different tyres of LSD's from Viscous to 2 & 3 open LSD centres. Yes they will take the torque and nearly all of the diff centres are interchangeable between similar models AND you can use V spec,R spec centres as well and these are the Jap equivalent of a 9" .
They come with 2 pot rear calipers and a working handbrake (drum in centre of disc hub).

[Tom Wells]

Rog246,

Interesting...

Wonder if Nissan sells anything in the US with that rear axle. If so, would you have any idea what they'd be called over here?

Tom

[Rog246]

Dunno !! No idea what Nissan sells over there sorry
I'd most likely try a search on a few Nissan forums, but Skyline GTR, real late Z's and a bunch of others, S14 springs to mind as well.
Rog

[cycleguy55]

Originally Posted by Tom Wells

Rog246,

Interesting...

Wonder if Nissan sells anything in the US with that rear axle. If so, would you have any idea what they'd be called over here?

Tom

Skyline R32 & R33 are RH drive and were never sold in NA, though some people are now importing them (Nissan Skyline - Wikipedia, the free encyclopedia).

The Skyline V35 was sold in NA as the Infiniti G35 from 2003 to 2006 - that's the IRS I was asking about. The V36 was sold as the G37 from 2007 - 2013, and was re-named the Q50. The current model is sold in NA as the Nissan GT-R. I have a G35x (AWD) in my garage, and I've seen a couple pop up in local salvage sales (G35 RWD and G35x AWD). Light weight 3.5L aluminum v6 with 380 - 306 HP, and I understand aftermarket engine management systems are now available for them. Hmmm....

Nissan / Infiniti uses a 114.3mm / 4.5" bolt circle, the same as Ford and, as noted by rog246, they have emergency / parking brakes standard (drum in centre of disc hub). The control arms are aluminum, making for reduced unsprung weight.

I've attached a .jpg of the G35 rear suspension assembly. It looks like there are 4 attachment points for the subframe, and separate mount points for coil springs and shocks, though I'm sure coilovers could be adapted.

Thoughts? Comments?

[cycleguy55]

Originally Posted by Tom Wells

Rog246,

Interesting...

Wonder if Nissan sells anything in the US with that rear axle. If so, would you have any idea what they'd be called over here?

Tom

Later model Skylines were sold in NA as the Infiniti G35, G37, etc. The only real bogies with these are the currently available limited slip units are quite a bit more $$ than similar ones for the Ford 8.8, etc.

I've attached a JPG showing the rear suspension assembly (including subframe) from the G35 sedan. I believe the G35 coupe is very similar, as is the Nissan 350Z and 370Z coupes. FWIW, there's a lot of aluminum in these, including the control arms. Track width for the G35 is 59.3", while I believe the FFR standard rear track width is around 58" - so the G35 is a touch wider.

[cycleguy55]

Originally Posted by Ralphy

Is the IRS a multi link design, or is it a double wishbone? Multi link would be a bit complicated to set up. Plus limited slips, limited supply as you said.

Ralphy

It's multi-link - but all the link mount points are on the subframe, so if it's installed as an assembly all the setup is handled. As you can see in the diagram I posted earlier it has separate mounts for springs and shocks, but perhaps that can all be handled with a single mount by using coilovers.

As it turns out, it appears all the 6MT (6 speed manual transmission) models were equipped with viscous limited slip differentials. So, it would be best to look for 6MT rather than one with the 5 speed auto. If you go with the auto you'd need to track down an LSD - either OEM or aftermarket.

Thoughts?

[Rog246]

there is a bunch of Nissan stuff that is interchangeable from multiple models.
I used a Skyline GTS-T auto (R33) in mine and it came with LSD. The ratios available is quite wide, mine happens to 3.7 to 1 (a bit lucky) most seem to come with 4.11 gears which would be ok as I'm using Tremec 6speed box behind my 5.4 DOHC.
Think I'm going to pick up a 4.1 when I finally get mine on the road.
There are a lot on EBay if your thinking of looking.
Rog