8.8 rebuild

Booboo

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The 8.8 rear end in my 1997 GT is making grinding noises. The plan is to rebuild it with 3.73 gears. I am wondering if I should replace the axles or differential too. The plan is get close to 350 wheel HP. Not a daily driver, only street driving.

Here is a pic of the tag on my existing setup. Anyone know what gear ratio it is, does it have 31 spline axles, Posi?
Gears.jpg
 

lwarrior1016

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I thought that bottom row would be the info.

3.08 gears 8.8 housing

It should be 28 spline axles. The axles should hold up to the power fine.
 
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Is the stock differential limited slip? Would it be worth while replaceing the differential with an upgraded one?
 

96blak54

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IIRC , F150 8.8 rear ends came 31 spline axles and limited slip. You can used the 31 spline limited slip in your mustang as a cheap upgrade if you want to do 31spline axles
 

cobrajeff96

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If it's only 350hp and street, don't bother spending on a different differential. You might as well just replace the clutch packs and not much else. They do make carbon fiber packs which is a bit better, can't vouch for them though. Higher spline count axles is definitely not necessary with your power goal. You can basically reuse everything but new bearings and seals are a must and replacing the clutch packs is just a no-brainer if you're already that far. Chances are it's a track-lok diff, so yes you could say it's a type of LSD but not a good one at that. If you put a 3.73 or better yet a 4.10 it'll really wake the car up where it needs it.
 
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Booboo

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I'm really on the fence with 3.73 and 4.10. It has an automatic transmission. I want to get a noticable improvment but I don't want it to be too much that it is not comfortable to drive. It is a car that I drive occasionally and do not race it.
 

lwarrior1016

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This is going to greatly depend on what you consider to be uncomfortable. With a 27 inch rear tire and 4.10 gears I cruise 80mph right around 3k rpm. I don’t mind and the engine doesn’t mind, but some folks find that uncomfortable.
 

waynenorcross

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The 8.8 rear end in my 1997 GT is making grinding noises. The plan is to rebuild it with 3.73 gears. I am wondering if I should replace the axles or differential too. The plan is get close to 350 wheel HP. Not a daily driver, only street driving.

Here is a pic of the tag on my existing setup. Anyone know what gear ratio it is, does it have 31 spline axles, Posi?
View attachment 18377
Curious about your plans to get 350 RWHP out of the 4.6L SOHC motor. With an automatic you will need 370 HP (rough guess) at the crank. If you are supercharging, that would make a difference on what gear ratio to choose if you decide to change. I went with 3:55s in my '94 Cobra because I had a Kennel Bell to go on and that would supply plenty of torque.
 

Wmac

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If you are planning upgrades to 350hp, then "beefing-up" the rear end is a good idea. 3.73 gears are just the ticket for any 4R70W trans. If you have any plans for drag radials, or slicks and any time at the track, 31 spline is the way to go.

All 2nd gen Explorers have 31 spline diffs. Door code D2 has 4.10 gears, D4 & L73 code is 3.73 gears. All these codes are trac lok. Plenty of 96 to 2001 explorers in the boneyard. 31 spline axles of your choice from summit, jegs, etc.
 
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Booboo

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Any idea of what labor should cost? A local shop just quoted me $750 if I supply the parts and oil. That is just the gear set and clutch pack. Seem very high to me. I was guessing it would be closer to $250.
 

cobrajeff96

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It's about right on the price. Can vary a bit but if someone quotes you $500 or less their end result might not be even worth that price. Any more than a thousand and they're just ripping you off. Just make sure, make sure, make sure that they use solid diff shims and not those thin-ass shim packs. Ask me how I know, lol.
 

lwarrior1016

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Any idea of what labor should cost? A local shop just quoted me $750 if I supply the parts and oil. That is just the gear set and clutch pack. Seem very high to me. I was guessing it would be closer to $250.
Not trying to be rude, but have you ever built a differential before? There’s a lot that goes in to it. It’s a full days work. If labor rate was $100 an hour, 8 hour day, that’s $800. I’d say that’s pretty close to correct.
 
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Booboo

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Was just asking. Didn't realize it was an 8 hour job.
 

tvsn95

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I agree with iwarrior and this is a not fun job and I would strongly suggest pulling rear and working on a bench.
FWIW when I broke my axles it ruined the carrier. new Detroit true track and 31sp axels over a $1000. I did the work.
 

cobrajeff96

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I knew I wasn't going to rebuild my IRS diff, I removed it from the car and handed it over to Powered By Ford in Orlando, FL. They did a perfect job, literally.
 

PinkieT

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Yep, $750 plus parts to do a rear is reasonable. I had a cracked differential carrier and my wife had broken limited slip gears, and so we had to do both in the last year.
 

b1pig

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Curious if you pulled the trigger on the rear end and what you ended up doing.
In my Jeeping experience, if you can find a reputable shop able to do a ring and pinion... any price you can get that is under $1000 with all parts is generally a good deal. From what I used to hear, most shops tended to hover in the $1200 range.

I had most of the tools and chose to do the work myself. I've done 3 Dana 35 axles, two Dana 30's and one Dana 44. They are all pretty similar to the 8.8, which has been a common swap for Jeep YJ (and some TJ) owners for years. Its not like changing plugs, for sure. It takes a lot of patience and following the setup guide. There's a reason why good mechanics charge a premium fee for ring and pinion setup. The first time I did a gear swap, it took me two days. Each axle I did got shorter and shorter with my understanding.


Only reason why I haven't regeared my gutless 07 JK is because I would rather hemi swap it. Rubicon already has 4.10 gearing. But the gutless wonder still gets me around. :)
 

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