Rear differential repair

n8bachelor

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Car has developed a noticeable grind/howl from the back end that I suspected was the differential (aka 3rd member).

Took it to the shop and they test drove it and put in on the lift to diagnose the problem. Shop said it was the pinion bearing going out making that noise. After the bill of parts and labor they wanted $1200 for a 7 hour job ($90/hr). Parts list included seals, bearings, fluid, etc.

I asked how long it would take to swap out for a new differential.... 3 hours.
I've called the shops around here and found one from an '04 LS for $300. I have not asked how many miles.

Now to my question: Does the Ford Thunderbird use the same differential as the LS? I have heard they do, but is it a direct swap? I'm not looking for better gearing or performance or anything like that.... just want it to run for another 50k.

I do not have the means to swap the part at home and do intend to shop for a more reasonable labor rate.

Any advice is appreciated.
 
I have an entire rear axle setup out of a 2004. 3.58 gears. Axle housing is in mint shape, gears are quiet, and axle housing bearings are quiet. CV shafts are perfect, driveshaft doesn't vibrate or make any center bearing noise, not sure if its anything your interested in. All pieces have 80k on them.

I think it will fit a GEN I.

Only reason its out is I have an 8.8 setup with a 1 piece axle. I'd rather sell it to someone on here that needs it, then throw it in the metal bin at work.

LS PARTS.jpg
 
I have a 2004 with 3.58 gears. You have what I need... but shipping that pumpkin from NH to AR would not be cheap. Are you willing to get a quote for me?

Any advice on swapping out the drive train? I thought the exhaust would have to come off but my coworker doesn't seem to agree. Can you swap a diff without dropping the exhaust on the LS?
 
Mine was rebuilt at 35k now im taking it again at 48 k its bad. Pinion moves 1/8th inch and dam it whines
 
why are these gears wearing out at such low mileage?
something like that ought to last 150k unless abused or run low on fluid.
 
How much did you pay for a rebuild? Did you drive it long after the noise started? I'm hoping to spend under $500


My LS has 102k.
 
why are these gears wearing out at such low mileage?
something like that ought to last 150k unless abused or run low on fluid.

Can't answer that but the same thing happened to my 02' F150. Luckily my mum works at Sterling Axle where they're made. Took it into the R&D department there and got it swapped for free. The thing whined like crazy.

I too noticed the diff whine when I first got my LS. Thought it was leaking, bought cv shaft seal, turns out it wasn't leaking. Fluid level was fine.

If you want to save a couple bucks the seal is yours if and when you may want it. Forgot how much I paid for it but I'm not going to be using it anytime soon.
 
Im going to be replacing my 8.0 for the 2nd time in roughly 8000 miles. I beat the piss out of it but whatever, it should still last longer than that.. 8.8 swap FTW
 
zip is 72712. I found a shop locally that has one for $300, just have to go get it.... they are only open M-F 8-5.

Does 3 hours sound about right for the time to install this unit?


Hoping I can get this done next week cause I'm planning a trip to KC on 11-12.
 
zip is 72712. I found a shop locally that has one for $300, just have to go get it.... they are only open M-F 8-5.

Does 3 hours sound about right for the time to install this unit?


Hoping I can get this done next week cause I'm planning a trip to KC on 11-12.

3 hours sounds ok.
 
Alldata has it at 7.5 hours labor but I believe thats for the entire rear assembly.
 
Let me know what you want to do I'll get a shipping price if you want.
 
Let me know what you want to do I'll get a shipping price if you want.

If you can tell me how much the differential weighs I can get rough shipping. I checked UPS with 60 and 100 lbs, the range was about $60-100 from you to me.

Will you sell just the diff? How much do you want for it?
 
Yeah, I'll get a shipping price and get right back to you.
 
I'm getting a similar sounding constant noise, it starts around 30mph and with a little vibration. I will be taking it to the shop next week to have them check it out. If I need a new diff, are they interchangeable between generations? I have a Gen I, could I install a Gen II differential?
 
I'm getting a similar sounding constant noise, it starts around 30mph and with a little vibration. I will be taking it to the shop next week to have them check it out. If I need a new diff, are they interchangeable between generations? I have a Gen I, could I install a Gen II differential?

As far as I know, they are geared differently so it's not a direct swap. Someone please confirm/deny.
 
When I bought mine in April I knew it needed something in the rear-end since it had a whine from about 45-60. I live in the Atlanta area so I found this place called S&W wrecking yard and they had a few of them available, I got mine for $159, including bearings and seals (which were in great shape, diff was from an '06 w/80K). I'm not sure where you live but I would try local wrecking yards, they can usually perform a cross-reference lookup and see what will work with your car based on some info.
 
I'm getting a similar sounding constant noise, it starts around 30mph and with a little vibration. I will be taking it to the shop next week to have them check it out. If I need a new diff, are they interchangeable between generations? I have a Gen I, could I install a Gen II differential?

IIRC the gen one has 28 spline axles and the gen 2 has 31 spline. I think the pinion is different too but im not sure
 
Are you absolutely certain its the pinion? Pinion's tend to make a whiny noise as well.

I have a humming/growling noise myself, took it to shop and its my drive shaft carrier bearing. As its been getting worse it makes quite the noise and causes quite the vibration right in the hump in the back seat.

There have been others on this forum who have replaced there entire differential too and it didn't fix the humming noise and ended up being this bearing.
 
You have to get it up on a lift, put it in gear, and have a second person walk around with a stethoscope. It could even be a wheel bearing (this was the case for me last month).

As for these rear ends not lasting, I don't know what to say. I have about 400 ft-lbs of torque and 285's out back. The drive line takes it all and I've had zero issues with 175K on the clock.
 
IIRC the gen one has 28 spline axles and the gen 2 has 31 spline. I think the pinion is different too but im not sure

Thanks Hite, if I need a new one I will look for a Gen I.

Are you absolutely certain its the pinion? Pinion's tend to make a whiny noise as well.

I have a humming/growling noise myself, took it to shop and its my drive shaft carrier bearing. As its been getting worse it makes quite the noise and causes quite the vibration right in the hump in the back seat.

There have been others on this forum who have replaced there entire differential too and it didn't fix the humming noise and ended up being this bearing.

Interesting, thanks for the heads up. I will have the shop look at it when I get back to town.

Is the carrier bearing a difficult/expensive repair?
 
Well I just ordered the part for $140 from the dealership. I myself can't do the job because it requires removing the exhaust and heatshield to access the driveshaft. And I don't have a garage or a lift.

But I am only being quoted about 2.5 hours of labor to do it, and where I live labor is dirt cheap, only $50 an hour.

If someone gets it on a lift, you can visibly see the play in the driveshaft, It moves around a lot, I actually think that the rubber around the bearing is the problem and not so much the bearing itself. Luckily the part comes with the whole assembly.
 
Are you absolutely certain its the pinion? Pinion's tend to make a whiny noise as well.

I have a humming/growling noise myself, took it to shop and its my drive shaft carrier bearing. As its been getting worse it makes quite the noise and causes quite the vibration right in the hump in the back seat.

There have been others on this forum who have replaced there entire differential too and it didn't fix the humming noise and ended up being this bearing.

Bschooled has a very valid point here. The center driveshaft carrier bearing has a habit of going out on these vehicles. If this is not fixed, it will cause premature failure of the pinion bearing, and possibly the tranny tailshaft bearing as well. On top of this, if a person is constantly spinning the tires, this causes premature wear of the spider gears, which will cause other intenals to wear out faster. Not so sure the traction control doesn't compound the issue by transferring torque load from side to side.

Does anyone have a factory posi unit in their vehicle? If so, have you had less or more issues with the diff?

Has anyone tried a swap of the 8.8 carrier from a late 90's T-bird, or an IRS Mustang? IIRC, the Mustangs used 28 spline axles, and the T-bird used 31. I may be wrong about this. It's been a while since I researched these diffs.

IRS diffs can't handle the abuse a solid axle can. That's why the new Mustangs have gone back to a solid axle. I haven't actually looked under a new Mustang to verify this. I'm just going by what someone told me.
 
No, there were no limited slip cars from factory. Yes, there is a handful of people who have done the 8.8 swap and the necessary drive shaft mods and custom fab housing mount bracket.

You may be right about the strength in general, but putting a SRA in the LS would be sacrilege. 8.8 IRS is plenty strong enough (close to the 9"), and even the 8.0 is plenty ample for anything this engine can dish out. Mustang likely went back to SRA for cost reduction... what a step backwards.
 

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