Singin' those Different(ial) Blues

Goose428

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Hello everyone,

Just went to a 5th autocross in my somewhat new to me 2008 Bullitt. The car did well.

But.....there's always a but

BAD one wheel peel. My car has a fresh trac-lok too. I looked into the matter and it seems if you autocross frequently, a different type of differential is almost a requirement.

It seems the common participants are the Auburn "Racer" (What differential is this actually? Couldn't find an actual auburn "racer" differential) and the torsen T2R. However, it seems the torsen's have been very problematic as of late.

Can anyone offer me their advice/experiences with what diff to get? I don't care about SCCA class btw.

Thanks!
 

redfirepearlgt

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Many guys in my area running their cars into the 9's regardless of setup will rebuild the limited slip carrier with an FRPP carbon fiber clutch kit. They actually buy two and add an additional clutch to the stackup as it was explained to me. I've brought up going to a Detroit locker to several and I have been told in each case the above mentioned is as good and it costs way less. That's my plan when I begin the one wheel wonder burnouts.
 
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Sky Render

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Many guys in my area running their cars into the 9's regardless of setup will rebuild the limited slip carrier with an FRPP carbon fiber clutch kit. They actually buy two and add an additional clutch to the stackup as it was explained to me. I've brought up going to a Detroit locker to several and I have been told in each case the above mentioned is as good and it costs way less. That's my plan when I begin the one wheel wonder burnouts.

This isn't drag racing. The carbon clutches still wear out quickly when autocrossing and road racing.

Vorshlag tested the carbon clutches and completely wore them out in one day on the road course.

Get a gear-type diff.
 

Goose428

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This isn't drag racing. The carbon clutches still wear out quickly when autocrossing and road racing.

Vorshlag tested the carbon clutches and completely wore them out in one day on the road course.

Get a gear-type diff.

I can attest to this. On my 2001 Bullitt, I had the track-lok rebuilt with carbon disks and they were gone after about 10 autocross runs. I was only on 300 treadware tires too. I heard the stickier the tire, the quicker they ware out.

I will look into the diffs you guys I have posted. I definitely want durability. I don't want to be opening up the diff once every couple of years....
 

Sky Render

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There are a few nationally-competitive drivers who replace the clutches after every autocross, because their class rules don't allow the use of other diffs.

Screw that noise.
 

Goose428

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Sky Render,

Could you send me a link for your exact diff? Lot's of results when I search eaton truetrac mustang.

And thank you for the article. Definitely confirmed that I want this to be my next mod.
 

Thenorm

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my OEM torsen does pretty well for me.
over 200 laps so far and going strong.
 

Sky Render

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Sky Render,

Could you send me a link for your exact diff? Lot's of results when I search eaton truetrac mustang.

And thank you for the article. Definitely confirmed that I want this to be my next mod.

http://www.jpcracing.com/detroit-truetrac-ford-8-8/
 

ExSRT8Guy

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The stock Trac-Lock wears out VERY quickly when doing corner carving.

Auburns don't hold up well, either.

You want an Eaton TrueTrac. 95% of the performance (bias ratio) of a Torsen T-2R, half the cost, and will hold up to way more abuse (including drag launches).

http://www.motoiq.com/MagazineArtic...art-5--Putting-the-Power-Down-with-Eaton.aspx

How noisy is the Eaton compared to the Trac-Lok? With poly everything in the rear suspension, you can really hear the stock setup clunk around slow corners.
 

Sky Render

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How noisy is the Eaton compared to the Trac-Lok? With poly everything in the rear suspension, you can really hear the stock setup clunk around slow corners.

If you're getting clunks with polyurethane, you installed something wrong, most likely a loose bolt somewhere.

The Eaton does have noticeable gear backlash noise during deceleration.
 

ExSRT8Guy

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If you're getting clunks with polyurethane, you installed something wrong, most likely a loose bolt somewhere.

The Eaton does have noticeable gear backlash noise during deceleration.

I should have been clearer. The clanking isn't from the suspension, it's from the diff. Taking all the rubber out of the suspension makes it much more noticeable. Experienced the same thing in my '97 Cobra years ago.
 

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