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questions on rear end

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Old Mar 23, 2010 | 08:48 AM
  #1  
IROC_Z89's Avatar
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From: Queens,NY
Car: 89 IROC-Z
Engine: 350 tpi
Transmission: 700r4
questions on rear end

My rear blew out on my car it was a 10 bolt posi disc.
Two questions:
1) If i buy a rear can i just use the middle section i.e. differential and gears?

2) If i bought a drum posi rear can i take the drums off and put on my disc setup

Thanks in advance for the help,
-Danny
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Old Mar 23, 2010 | 09:01 AM
  #2  
DJP87Z28's Avatar
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Re: questions on rear end

Originally Posted by IROC_Z89
My rear blew out on my car it was a 10 bolt posi disc.
Two questions:
1) If i buy a rear can i just use the middle section i.e. differential and gears?

2) If i bought a drum posi rear can i take the drums off and put on my disc setup

Thanks in advance for the help,
-Danny
1) yes, if the axle shaft spline count are the same for the 10-bolt.
2) yes, if the disc backing plates will fit.
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Old Mar 23, 2010 | 09:04 AM
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Car: 1992 Camaro RS
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Transmission: WCT5, 7k & counting behind the 350
Axle/Gears: 4thgen disc rear w/ 3.73 Posi
Re: questions on rear end

In order:

1 - It depends on how much damage was done to the housing when it went, and what you get the center section out of. You can use one out of any 3rd or 4th gen F-body or one out of an 82-97 S10/S15/Blazer/Jimmy. Possibly a few others, but those are the ones I know for sure will work.

2 - Yes, as long as both are F-body rears its a pretty straightforward swap.

EDIT:
DJP87Z28 is correct, the axle spline count must be the same, I forgot about that. Or you could swap matching axles too.
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Old Mar 23, 2010 | 09:07 AM
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Re: questions on rear end

The 7.5 10 bolt uses a 2 series differential for 3.08 to 2.41 gears and a 3 series for 3.23 to 4.10 gears. You must use the right series for the gears. There are 26 and 28 spline axles. You must use the right differential for the axles that you have. You can not simply unbolt the internal parts from one rear end and bolt thenm into another housing. You MUST set the pinion depth, bearing preload and backlash whenever you change parts from one housing to another.
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Old Mar 23, 2010 | 09:12 AM
  #5  
IROC_Z89's Avatar
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From: Queens,NY
Car: 89 IROC-Z
Engine: 350 tpi
Transmission: 700r4
Re: questions on rear end

so i would be better of just buying a whole rear from third or fourth gen and put it in
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Old Mar 23, 2010 | 10:06 AM
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Re: questions on rear end

It would be easier, but is this one bad enough that you think you need to replace it?
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Old Mar 23, 2010 | 10:11 AM
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Car: Met. Silver 85 IROC/Sold
Engine: 350 HO Deluxe (350ci/330hp)
Transmission: T-5 (Non-WC)
Axle/Gears: Limited Slip 3.23's
Re: questions on rear end

Originally Posted by IROC_Z89
If i bought a drum posi rear can i take the drums off and put on my disc setup
Not without a kit or modification to the axle flanges. More info about that, along with combination valve, parking brake cables, and speedo gears, in the link to following.

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC
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Old Mar 23, 2010 | 10:27 AM
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IROC_Z89's Avatar
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From: Queens,NY
Car: 89 IROC-Z
Engine: 350 tpi
Transmission: 700r4
Re: questions on rear end

Originally Posted by big gear head
It would be easier, but is this one bad enough that you think you need to replace it?
yeah the diff is gone in a straight line its ok but as soon as i turn and drive i get a horrible noise, i know my cone was damaged, it was only a matter of time
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Old Mar 23, 2010 | 11:28 AM
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Re: questions on rear end

Originally Posted by big gear head
The 7.5 10 bolt uses a 2 series differential for 3.08 to 2.41 gears and a 3 series for 3.23 to 4.10 gears. You must use the right series for the gears. There are 26 and 28 spline axles. You must use the right differential for the axles that you have. You can not simply unbolt the internal parts from one rear end and bolt thenm into another housing. You MUST set the pinion depth, bearing preload and backlash whenever you change parts from one housing to another.
Don't confuse the issue, He stated he wanted to use the COMPLETE center section of the rear. This he can do, no matter if it is a 2 or 3 series carrier as long as the axle shaft spline count is the same.
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Old Mar 23, 2010 | 11:54 AM
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Re: questions on rear end

Yes, I know. I just wanted to be sure that he understood that it wasn't a simple unbolt and bolt in job. It still must be set up correctly.
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Old Mar 23, 2010 | 01:01 PM
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Re: questions on rear end

Originally Posted by big gear head
Yes, I know. I just wanted to be sure that he understood that it wasn't a simple unbolt and bolt in job. It still must be set up correctly.
Nothing moves....it is a complete unit. Pull the axle shafts, remove dr shaft and remove 10 diff caarier bolts to the axle housing. So what do you need to set up?????
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Old Mar 23, 2010 | 01:10 PM
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Transmission: WCT5, 7k & counting behind the 350
Axle/Gears: 4thgen disc rear w/ 3.73 Posi
Re: questions on rear end

Originally Posted by DJP87Z28
Nothing moves....it is a complete unit. Pull the axle shafts, remove dr shaft and remove 10 diff caarier bolts to the axle housing. So what do you need to set up?????
BGH is right, you need to set it up properly if you want it to last. Pinion depth, backlash, and pattern must all be set.

If you swap the whole center section, the only thing you don't have to to worry about is if the gears will fit the carrier if you use the everything from the same axle. If the OP is talking about just swapping the carrier over to his ring & pinion then he will definitely need to make sure the carrier fits the ring gear.

EDIT: Its also a good idea to change the bearings on the carrier when you swap it. It really sucks pulling something back apart 2 months after you put it in just to fix something you could have done the first time. Plus, they will probably be worn to the axles they originally came with, not his axles.
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Old Mar 23, 2010 | 08:23 PM
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Re: questions on rear end

Originally Posted by DJP87Z28
Nothing moves....it is a complete unit. Pull the axle shafts, remove dr shaft and remove 10 diff caarier bolts to the axle housing. So what do you need to set up?????
I don't know if I'm not understanding you or if you are not understanding me. Are you talking about changing the complete rear end or the internal parts? If you are talking abouot swapping the complete rear end then there is nothing to set up. If you are talking about removing the ring & pinion gears and differential then the pinion depth, bearing preload and backlash MUST be set again. You are talking about things that are set to +/- .001 inch and there is much more than that amount of machining tollerances between each housing.
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Old Mar 24, 2010 | 06:48 AM
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Re: questions on rear end

Originally Posted by big gear head
I don't know if I'm not understanding you or if you are not understanding me. Are you talking about changing the complete rear end or the internal parts? If you are talking abouot swapping the complete rear end then there is nothing to set up. If you are talking about removing the ring & pinion gears and differential then the pinion depth, bearing preload and backlash MUST be set again. You are talking about things that are set to +/- .001 inch and there is much more than that amount of machining tollerances between each housing.
You are the one that is confused. I am not taking any parts from the donor rear, just the COMPLETE DIFF CARRIER assembly intact and installing it in place of the old one on the car.

Last edited by DJP87Z28; Mar 24, 2010 at 07:37 AM.
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