Drivetrain Rear end Question

Aoneill5.0

Member
Sep 30, 2022
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EASTERN CANADA
Hi

recently bought 89 GT

Found a rear end repair Reciept with some details

it came into the shop locked up

mechanic replaced gears with 373
Shimmed up everything and kicked it out the door,
It’s still the 8.8

anyway I have been driving the car, no real issues except that I noticed only 1 rear wheel spin.
Drivers side mostly unless on gravel

anyway I jacked up the rear, spun each wheel expecting to see the other go opposite
But no, I the other tries to go same direction but won’t, fast spin or slow..

can someone tell me from this, do you believe the diff is a locker, limited slip or standard diff

seems like there may be clutches in there just worn maybe??
Thanks

Andy
 
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Rdub6

So while I wait to figure out my rear end issues
5 Year Member
Dec 29, 2017
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I don’t have a ton of experience with this, but I did just recently rebuild my own rear end. I painstakingly watched videos and read articles during the process, and in the end, it runs awesome. I would bet that all they did was change the gears and throw it back together. I’d say that your clutches are shot and need to be redone.
 

Jimmer009

Member
Jan 4, 2022
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Ny
So the rear end in the mustang is a limited slip. It is a crappy version of one though. There are clutches on both sides that you can replace. But buy a trac lok if you want posi. It's a great way to spend 4-500$.

Rear end gears are something I grown into. The 8.8 is actually easier than say a 9 inch. If you have the capability to torque the crush sleeve it's about 220ftlbs. Then you have to use a dial caliper to measure play in the gears then paint them and spin it for like 10 minutes. It's definitely doable if you have the tools and a afternoon and some ocd helps. Also YouTube will/can walk you threw it in like 8 different languages
 

96pushrod

I think they're a little easier to get off
May 15, 2018
1,478
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Savannah
That gt should have a trac lok in it. As stated it probably just needs the clutches replaced. You can buy the carbon clutch rebuild kit from ford performance and do it yourself, or find someone who has experience doing them and get a hand.

They’re actually pretty stout If rebuilt with the carbon clutches
 

Bullitt347

I have been doing it wrong this whole time
15 Year Member
Mar 23, 2007
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The 8.8 is actually easier than say a 9 inch.
I completely disagree with this statement. I can set up a 9" on the bench. You can not do that with a 8.8". I can change pinion depth on a 9" and never have to press the pinion bearing on and off to access the shim, unlike a 8.8". I can change backlash on a 9" and never have to change the carrier shims, unlike a 8.8". The only advantage the 8.8 has is that it is an overall lighter assembly and the pinion placement is more ideal. Otherwise the 9" is not only the stronger rear assembly but by far the easiest to work on. I can have another 3rd member assembled and ready to swap out with a 9" while the 8.8" would require complete disassembly to swap gears
All that being said, I run a 8.8" for the reasons stated above, it is lighter and because of pinion placement it takes less HP to operate. It can also be built to take a ton of power, but still not anywhere near the power level of a 9"
 
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limp

wrap a little cheese around it and its a done
Oct 4, 2020
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Bullitt347, I still think the 8.8 is easier. You have some good points and and knowledge about them. But let's stay on topic, as it don't matter witch axel we prefer.
Lets stay on topic.... LOL...
DSCF0957.JPG
 
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Bullitt347

I have been doing it wrong this whole time
15 Year Member
Mar 23, 2007
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Bullitt347, I still think the 8.8 is easier. You have some good points and and knowledge about them. But let's stay on topic, as it don't matter witch axel we prefer.
Lol. You are the one that brought up the 9"
I replied to your premise.
I disagreed with that premise and gave the reasons why.
I even said I run a 8.8" rear end. It is in a 1,300 HP car.
So...yeah.
 
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