Drivetrain 91' Mustang - Best Posi Unit For The Street?

Exile · Sep 24, 2012

I have a 91' 5.0 Mustang LX-Hatch, and am getting ready to rebuild the 8.8 rear end. It has 4:10 gears with a mini spool in it now, and I absolutely hate driving it on the streets!

What I do know so far is that the new rebuilt rear end will have 3:73 gears, and Moser 31 spline axles.

But im debating on which posi unit that I should go with? Right off im trying to decide between a Detroit Trutrac unit, or a Detroit Locker?

It will mainly be a fun lil daily driver that might see the drag strip maybe a few times a year. I will admit that I do like to get her sideways from time to time, and possibly swinging a few donuts here, and there. (I know, I know)

So that being said I dont think I would want the Detroit locker unit for those reasons? So I am boiling it down to the Detroit Truetrac unit, but I wanted to hear from some other people on what they thought might be the best posi unit for the street?

Any feedback/thoughts/opinions are appreciated!

Noobz347 · Sep 24, 2012

Get a Trak-Lok from an F-150 (31 spline) and rebuid it with the extra clutch.

Often, you can buy them on ebay all ready to go.

Better street manners than any of the options you've listed. It's just an OEM traction lock, exactly like the one that came in your 91 from the factory but beefed up slightly.

2000xp8 · Sep 24, 2012

Just buy a new one from ford racing meant for the 03 cobra.
Shop well and you'll find you can get it cheap, i had coupon code for somewhere (can't remember) got mine for $225.
At that price, it's not worth rebuilding anything else.
It's also 31 spline.

srtthis · Sep 24, 2012

03/04 cobra diff (stock with carbon fiber clutchs)
05+ have 31 spline like the 03/04's (some had the CF clutch pack)
01 cobra had a 31 spline diff also

and any of the trucks or explorers with 8.8's also had 31's i believe

any of these rebuilt with the CF clutch pack will be good to go!

Exile · Sep 24, 2012

What year trucks (F-150's), and Explorers should I be looking for a Trac-Lok diff from?

Does it matter what size motors they come off of?

srtthis · Sep 24, 2012

http://forums.corral.net/forums/5-0-5-8-engine-tech/1092402-junkyard-horsepower-summary.html

acording to that... 84+

Exile · Sep 24, 2012

Or how does this new Trac Lok unit with carbon fiber clutches compare to the Cobra/Trucks/Explorers factory Trac Lok units? Better? Worse? Same?

Ford Racing M-4204-F318C
http://www.summitracing.com/parts/FMS-M-4204-F318C/

srtthis · Sep 24, 2012

you can buy the clutch pack from summit or ford its around 100 bucks. and you can have the diff from a junk yard for around 50 depending on the yard.

half dozen of 1 or 6 of the other.
im curious of the other threar i just started about the CF clutch pack and the over packed stock pack. which is actually tighter

2000xp8 · Sep 25, 2012

Exile said:
Or how does this new Trac Lok unit with carbon fiber clutches compare to the Cobra/Trucks/Explorers factory Trac Lok units? Better? Worse? Same?

Ford Racing M-4204-F318C
http://www.summitracing.com/parts/FMS-M-4204-F318C/

That's the cobra one.

Just buy it, no sense in building something you can buy, if it were a massive savings i'd say build your own, but by the time you count in going to a JY and finding one or getting one shipped in from ebay, then the clutch kit+shipping, savings are minimal.

Noobz347 · Sep 25, 2012

2000xp8 said:
That's the cobra one.

Just buy it, no sense in building something you can buy, if it were a massive savings i'd say build your own, but by the time you count in going to a JY and finding one or getting one shipped in from ebay, then the clutch kit+shipping, savings are minimal.

Troofs... I tooled around on ebay last night for a little. When I bought mine, it was $110 for one completely rebuilt with the extra clutch. Ready to go. The ones I saw on ebay were over $100 and were NOT rebuilt. So for the $250 or so bux that xp8 is talking about, that's pretty much a steal... Particularly for a new unit with the CF clutch pack installed.

Exile · Sep 25, 2012

Ok so lets say I was to get the following...

Ford Racing Diff - M-4204-F318C
http://www.summitracing.com/parts/FMS-M-4204-F318C/

Ford Racing 3:73 Gears- M-4209-88373
http://www.summitracing.com/parts/FMS-M-4209-88373/

Moser 31 Spline Axles - A883141
http://www.summitracing.com/parts/MSR-A883141/

What else am I missing/needing to complete a complete rear end rebuild?

srtthis · Sep 25, 2012

bearings
shims
seals
crush sleeve
fluid
friction modifier

srtthis · Sep 25, 2012

i believe the ford racing kits come with pinion nuts but youll need a new one of them also if it doesnt come with one

Exile · Sep 25, 2012

srtthis said:
bearings
seals
shims
crush sleeve

I have never rebuilt a rear end before, so please bare with me.

Moser 9563 Axle bearings & seals.
http://www.summitracing.com/parts/MSR-9563/

Pinion Nut
http://www.summitracing.com/parts/RAT-1502/

How many Crush Sleeves do I need? 2?
http://www.summitracing.com/search/...e-Model/Ford-8-8-in/Brand/Ratech/?Ns=Rank|Asc

And as far as the shims goes, do I need carrier shims, or pinion shims? Or both?
http://www.summitracing.com/search/Part-Type/Differential-Shims/Axle-Model/Ford-8-8-in/

srtthis · Sep 25, 2012

1 crush sleeve

pinion shims and carrier shims

srtthis · Sep 25, 2012

http://www.summitracing.com/parts/BCA-RA311MK/
that would be the best route

Exile · Sep 25, 2012

srtthis said:
http://www.summitracing.com/parts/BCA-RA311MK/
that would be the best route

I do like the looks of that kit with everything in one kit, but it shows to be for 30 spline axles? I will be running 31 spline axles. So that kit wont work for me will it?

srtthis · Sep 25, 2012

Exile said:
I do like the looks of that kit with everything in one kit, but it shows to be for 30 spline axles? I will be running 31 spline axles. So that kit wont work for me will it?

thats the pinion spline count not axle spline count

Exile · Sep 25, 2012

srtthis said:
thats the pinion spline count not axle spline count

Ah ok... I had just read over the specs real quick, and seen "spline count 30", and didnt realize it actually said "pinion spline count 30".

I think that will be the kit that I go with then! Thanks!

srtthis · Sep 25, 2012

no problem!

Drivetrain 91' Mustang - Best Posi Unit For The Street?

Exile

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Noobz347

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2000xp8

srtthis

the guy doing it does every local racers rear end

Exile

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srtthis

the guy doing it does every local racers rear end

Exile

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srtthis

the guy doing it does every local racers rear end

2000xp8

Noobz347

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Exile

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srtthis

the guy doing it does every local racers rear end

srtthis

the guy doing it does every local racers rear end

Exile

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srtthis

the guy doing it does every local racers rear end

srtthis

the guy doing it does every local racers rear end

Exile

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srtthis

the guy doing it does every local racers rear end

Exile

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srtthis

the guy doing it does every local racers rear end

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Drivetrain 91' Mustang - Best Posi Unit For The Street?

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Stangnet Facilities Maint Tech... Er... Janitor

the guy doing it does every local racers rear end

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the guy doing it does every local racers rear end

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the guy doing it does every local racers rear end

Stangnet Facilities Maint Tech... Er... Janitor

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the guy doing it does every local racers rear end

the guy doing it does every local racers rear end

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the guy doing it does every local racers rear end

the guy doing it does every local racers rear end

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the guy doing it does every local racers rear end

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the guy doing it does every local racers rear end

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