How about a 98 cobra differential? - TCCoA Forums
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post #1 of 11 (permalink) Old 06-26-2016, 03:33 AM Thread Starter
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How about a 98 cobra differential?

I tried to do some skimming on the subject. I understand the necessary 28 spline diff is needed. But, everything I read always says get a 1999 cobra diff.

All the google searching I've done says the 98 is also a 28 spline. Wouldn't that be compatible as well?

I've found one that's close to me. All the 99's I've come across want big bucks for the complete rear end and they are all 14 hours east of me.

Someone please make my morning and say this 1998 Cobra diff would work.
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post #2 of 11 (permalink) Old 06-26-2016, 08:32 AM
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Quote:
Originally Posted by mandersen View Post
I tried to do some skimming on the subject. I understand the necessary 28 spline diff is needed. But, everything I read always says get a 1999 cobra diff.

All the google searching I've done says the 98 is also a 28 spline. Wouldn't that be compatible as well?

I've found one that's close to me. All the 99's I've come across want big bucks for the complete rear end and they are all 14 hours east of me.

Someone please make my morning and say this 1998 Cobra diff would work.
I'm fairly certain the 1998 Cobra was a solid rear axle, the first IRS Cobra was 1999, ending in 2004.

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post #3 of 11 (permalink) Old 06-26-2016, 09:13 AM
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No, the 98 Cobra has a solid rear axle. The 99-04 Cobra got IRS, like our cars. 2000 was only the Cobra R, so good luck finding one of those, and starting in 01, the Cobra got 31 spline axles, so that leaves the 99 Cobra diff as the only completely bolt-in swap for the aluminum case and trak-lock diff. Alternatively you could get a MarkVIII housing and swap in a trak-lock diff and whatever gear ratio you want.

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post #4 of 11 (permalink) Old 06-26-2016, 05:25 PM Thread Starter
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Thanks for the replies.

Ok, then the seller definitely doesn't know what he has. He's got a picture up for an IRS system and claims it was from a 98 cobra. He claimed that it's at his fathers house and doesn't have tools to take off the cover and doesnt know the spline count.

He was asking $600 or best offer for the whole rear end minus the calipers. Not sure if it would be worth picking up.
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post #5 of 11 (permalink) Old 06-26-2016, 05:26 PM Thread Starter
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Especially when I can pick up a mark's diff from the junk yard very easily and a lot cheaper too like you said Mike.
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post #6 of 11 (permalink) Old 06-27-2016, 01:46 PM
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The stock 8.8 is fine, unless you are doing a huge torque converter with a trans brake or a stick car launching at the red line.

Then you might need the DSS axles, the kind with the larger outer
stub.

Thats what breaks most of the time.

I broke three.

Now I run DSS axles on my mostly drag racing car.


If you want to look fancy, buy the special differental cover, those look cool.

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post #7 of 11 (permalink) Old 06-27-2016, 09:14 PM Thread Starter
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I was thinking about upgrading my gears to 3.73's. The local reputable driveline shop wants around $600 in labor to it. So, i thougt i could be potentially more cost effective to just find one of these diffs with that gear already installed.
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post #8 of 11 (permalink) Old 06-27-2016, 09:55 PM
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99 Cobras used 3.27s, not 3.73s. There used to be pre assembled 3.73 differentials for them available through Ford parts but those are long obsolete now.

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post #9 of 11 (permalink) Old 06-28-2016, 11:02 AM
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I think the 99 Cobra was also 28 spline. I don't believe they upgraded to the higher spline rear end until they came out with the Terminator Cobras with the factory blower.

97 Thunderbird LX (The GT Bird)
2003 Explorer WAP block with Modular Head Shop "street ported" heads and Stage 2 PI NA cams, 75mm Accufab throttle body, C&L upper intake plenum, Kooks 1.75" primary/3" collector headers, 2.5" full exhaust with mid mount Magnaflow dual in/out muffler, 24lb/hr injectors, 80mm MAF, Tuning from Don @ www.lasotaracing.com, CAI that feeds from fenderwell. Jmod, 3.73:1 TL in Mark VIII carrier, Mark VIII aluminum LCAs, 93 Mark VIII driveshaft, PBR brakes (soon to be Cobras), 18x9 wheels with 35mm offset, 255/40/ZR18 Tires, Front and Rear strut/shock bracing, GR-2 shocks, Eibach 1.5" springs, 1989 SC front and rear sway bars.
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post #10 of 11 (permalink) Old 06-28-2016, 11:16 AM
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Quote:
Originally Posted by Woodman View Post
I think the 99 Cobra was also 28 spline. I don't believe they upgraded to the higher spline rear end until they came out with the Terminator Cobras with the factory blower.
01 is 31 spline. There were a lot of half baked issues with the 99 Cobras going past the manifold recall, the IRS wasn't well sorted either and SVT spent that gap between 99 and 01 improving that too, including the 31 spline inners.
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post #11 of 11 (permalink) Old 06-29-2016, 12:34 AM Thread Starter
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Has anyone sucessfully pieced the two half shafts together? Put the 31 spline from the cobra onto our tbird halfshaft?
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