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Discussion Starter · #1 ·
Pulled the brakes apart, axles out (new Mosers going in), and center section out. Supposedly the rear diff was rebuilt/converted by the dealer back in the early/mid 90's (have the reciepts). Here's where it gets odd...the diff is a limited slip unit, not a posi unit, and the ring gear is stamped 3.37. Would the center section out of a 7.5" 10 bolt actually bolt into the 8.5" rear? Dunno where else they would have gotten a 3.37 gear from. Kinda sucks though...now I have to buy gears, posi, and bearings instead of just rebuilding what I though was a dealer installed G80 unit... :pissed: :crying: :help:
 

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No way a 7.5" carrier will work in an 8.5" rear.
Look at the differences in the ring gear diameters.
You'd need an extra long,protruding pinion gear to reach the ring teeth.
I would count the teeth and do the math.
 

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Discussion Starter · #3 ·
Ok, rules that problem out. Did any other cars come with a 8.5 LSD? I need to replace the gears anyway.....found a tooth on the ring gear with a small chip in it. Probably wouldn't hurt to reuse the gears, but since everything else will be new, might as well do gears as well. Fuggin money pit......lol.
 

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Turbocharged BrunoStachel
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Limited slip and Posi are the same thing. You could get the 8.5 in just about anything. How are you coming up with the 3.37 number? Divide the number of teeth on the pinion gear by the number of teeth on the ring gear.
 

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Discussion Starter · #5 ·
The 337 was stamped on the ring gear, but I'm going to go count the teeth in a bit. Willing to bet it's actually the 3.42 gearset, especially if the part #'s match the shop ticket from 1995.
The open diff wouldn't have any spider gears in the housing, would it? This is the first Buick rear I've had cracked open....used to dealing with Ford 8.8's w/Trac Lok diffs. Rear was torn down when I got to the shop, so just the center chunk was setting on the bench. Definitely had spiders in it though.
 

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Slo86GN said:
The 337 was stamped on the ring gear, but I'm going to go count the teeth in a bit. Willing to bet it's actually the 3.42 gearset, especially if the part #'s match the shop ticket from 1995.
The open diff wouldn't have any spider gears in the housing, would it? This is the first Buick rear I've had cracked open....used to dealing with Ford 8.8's w/Trac Lok diffs. Rear was torn down when I got to the shop, so just the center chunk was setting on the bench. Definitely had spiders in it though.
Stock 8.5" Posi's will have spiders. It will also have a means of applying preload to the axle "spiders". Usually a peice of flat steel shaped in an extended "S".
 

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Turbocharged BrunoStachel
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Slo86GN said:
used to dealing with Ford 8.8's w/Trac Lok diffs.
It should be the same thing from what very little I know about Fords.
 

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turbofish38 said:
It should be the same thing from what very little I know about Fords.
No. I am a big fan of a 9" ford. I believe 8.8 & 9" look the same. If so, they look nothing alike.
 

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Turbocharged BrunoStachel
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wmsonta said:
No. I am a big fan of a 9" ford. I believe 8.8 & 9" look the same. If so, they look nothing alike.
Isn't the 8.8 an Eaton carrier with C-clips? A Salisbury type differential? :dunno: Now I do know the 9" and the 8" look alike.
 

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turbofish38 said:
Isn't the 8.8 an Eaton carrier with C-clips? A Salisbury type differential? :dunno: Now I do know the 9" and the 8" look alike.
You have got me Eric. This country is over run with Fox bodies. I'll have to look. I have degree'd the cams in a couple, never paid any attention to anything else.

Thinking about it, I think you're right.
 

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Discussion Starter · #11 ·
wmsonta said:
Stock 8.5" Posi's will have spiders. It will also have a means of applying preload to the axle "spiders". Usually a peice of flat steel shaped in an extended "S".
So an open diff will be just that....no spiders in the housing? I'll take a closer look at it in a bit. Not that it matters much.....Moser Pro Spool is on it's way, along with Ratech install kit and new 3.42 gears. At least I won't have to worry about breaking **** in the rear....lol.
 

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Slo86GN said:
So an open diff will be just that....no spiders in the housing? I'll take a closer look at it in a bit. Not that it matters much.....Moser Pro Spool is on it's way, along with Ratech install kit and new 3.42 gears. At least I won't have to worry about breaking **** in the rear....lol.
No, an open rear will have spiders, but no means of preload.

Locked rears can be trouble on the street. JMO
 

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Discussion Starter · #13 ·
turbofish38 said:
Isn't the 8.8 an Eaton carrier with C-clips? A Salisbury type differential? :dunno: Now I do know the 9" and the 8" look alike.
Pretty much.....they are C-clip axles and like Buicks, don't like lots of power + traction..makes a mess. The ring/pinion and Trac Lok are tough as nails though. The 8.8 is similar to our 8.5 when it comes to strength/durability once built.
 

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Discussion Starter · #14 ·
wmsonta said:
No, an open rear will have spiders, but no means of preload.
Ok, got'cha. What's wierd is the car would spin both tires on wet roads, dirt, etc, but as soon as it got any type of grip....one wheel peel. I'm gonna ride over to the shop in just a few to make sure it's still the factory open diff. According to the shop invoice from '95, they used the GM open diff during the rear overhaul....checked the part numbers against GM parts direct listing for the 87 Regal. Just wanna double check, if for no other reason than to know more about the car....lol.
 

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Discussion Starter · #15 ·
wmsonta said:
No, an open rear will have spiders, but no means of preload.

Locked rears can be trouble on the street. JMO
Well, it's going to be more of a weekend driver/track toy, so it won't see much foul weather driving. May cruise over to different cruise-ins/gatherings, but that's about it. I would rather deal with chirping tires going around a slow corner/turn than worrying about killing the posi after repeated transbrake launches. Eventually going to a th400 w/brake, so might as well put the spool in now while it's apart.
 

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Slo86GN said:
Ok, got'cha. What's wierd is the car would spin both tires on wet roads, dirt, etc, but as soon as it got any type of grip....one wheel peel. I'm gonna ride over to the shop in just a few to make sure it's still the factory open diff. According to the shop invoice from '95, they used the GM open diff during the rear overhaul....checked the part numbers against GM parts direct listing for the 87 Regal. Just wanna double check, if for no other reason than to know more about the car....lol.
A worn out posi will act like an open rear end. To convert an open to posi only requires a carrier change and setup.
 

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I just had a spool with 33 spline axels put in. Bit of a bear on the street but should work at the track. Wouldn't want to make a daily driver out of it.
 
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