Mustang Cobralopnik

Kinja'd!!! "RazoE" (razoe)
10/01/2015 at 12:19 • Filed to: None

Kinja'd!!!0 Kinja'd!!! 11

FoxbodyOppos

Hi guys, this is for my broseph-in-law. He has a 1999 Cobra and his rear differential mounts broke off. We’ve been doing some research but there are still a few questions we have.

1999 Cobras have a differential (28 spline) that’s not compatible with a pre-99, nor a 2001 (as it’s 31 spline). 2000 cobras are all Cobra Rs (good luck finding one of those), So it has to be from another 99 Cobra, right?

You can swap over to 31 spline axles for a 2001/2002 (31 spline) differential, but a 2003/2004 is much stronger.

We’ve seen 31 spline conversion axles, but they all say GT/Bullitt/ etc, just not Cobra, or they’re for a pre-99.

Can you use 28 spline axles from another Ford? Can you use 31 spline axles from a different car?

Also, last question, do 99 cobra differentials share their pumpkin with any other car? That’d be the easiest.

Please let us know folks, thank you!

p.s. Finding a 99 Cobra differential for sale is nearly impossible, if there are any for sale that you know of online (I’ve tried my google/ebay/craigslist-fu, but no luck), please post them up.

Terminators for your time

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DISCUSSION (11)


Kinja'd!!! crowmolly > RazoE
10/01/2015 at 12:28

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‘99 Cobra is an IRS so basically other axles are out. I think you are going to have to find another ‘99 center section or swap up to a newer model. Maybe you can find an aftermarket diff case/bare housing? Where did the mounts break?

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Kinja'd!!! RamblinRover Luxury-Yacht > RazoE
10/01/2015 at 12:30

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I think the same pumpkin (the aluminum one) is in the Mark VIII. Iron version in Thunderbird.

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If the spline count doesn’t match, you could most likely swap the carrier and/or spiders.


Kinja'd!!! 66671 - 200 [METRIC] my dash > crowmolly
10/01/2015 at 12:33

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Kind of off topic but didn’t most Gen mustangs up until 2015 or so have non-irs?


Kinja'd!!! RamblinRover Luxury-Yacht > crowmolly
10/01/2015 at 12:33

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The case is actually one of the easier parts - unless I’m very, very wrong it’s the same as the Mark VIII, or the Thunderbird (in steel). It may even be the same case as some of the earlier IRS Exploders. Short version, finding another Cobra IRS is not really necessary.


Kinja'd!!! crowmolly > 66671 - 200 [METRIC] my dash
10/01/2015 at 12:34

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Cobras are IRS starting in 1999.


Kinja'd!!! crowmolly > RamblinRover Luxury-Yacht
10/01/2015 at 12:38

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Could very well be. I know the half shafts and control arms are different but the case might be the same?


Kinja'd!!! RamblinRover Luxury-Yacht > 66671 - 200 [METRIC] my dash
10/01/2015 at 12:40

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Like Crowmolly says, the Cobra went IRS in 99. However, because the whole setup is based on existing Ford IRS stuff and on squishy rubber bushings, they kind of went over like a lead balloon. You *can* make them really nice, but a lot of people just swapped them for live axle. The Cobra IRS setup was designed to pretty much bolt into anything Fox-body without issue, and with light tweaking can be put in a 1st gen as well, by design. They weren’t utilized that much that way, but that was the idea.


Kinja'd!!! RamblinRover Luxury-Yacht > crowmolly
10/01/2015 at 12:43

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Ford parts-bins very weirdly and inconsistently, but this is one of the times that I think they did the obvious thing.


Kinja'd!!! RazoE > RamblinRover Luxury-Yacht
10/01/2015 at 12:51

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Yeah, we weren’t looking for an entire IRS, just the differential housing, or entire diff if need be. I’ll look into the MKVIII/Thunderbird.


Kinja'd!!! RazoE > RamblinRover Luxury-Yacht
10/01/2015 at 12:51

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Thanks!


Kinja'd!!! RamblinRover Luxury-Yacht > RazoE
10/01/2015 at 12:58

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I only know this much about them because I was weighing using a Cobra, Mark, or T-bird IRS in my project. Ended up going Jag, but I’ve seen the Cobras pop up for sale from time to time. There was a time when the Cobra IRS setups weren’t hard to find because a lot of the Cobra guys building for more power went back to the live axle, but these days most of the guys with one aren’t getting rid of it.