Changing Rear End Gears...HELP

bigdaddy999 · 08-07-2005, 08:56 AM

I was wondering how hard it was to change the gears in a rear, if the rear is already out of the car. is it just opening up and switching out, or is it alot more complicated than that? If anybody has done this please le me know.

Jeff Chambers · 08-07-2005, 09:50 AM

Take it to someone who knows how to do it right. There's nothing magical about it, but if you have to ask, then you probably don't have the tools to do it right anyways. Not tryin' to 'dis you, but it takes some special tools and knowledge to really do it right. Some folks will just slap them in, but there's no substitute for doing it right.

ols0051 · 08-07-2005, 03:41 PM

If you have someone able to do the job right, go for it. But if not I wouldn't fear giving it a try. I did mine but have not yet driven the car to see if I did a good job or not. I have had to ask about a ton of things I've done but I have always found good help here. So if you get stumped ask. You will find a ton of people that are very experienced with things like this. You will need a dial indicator for the backlash, and a shim pack. A machine shop to press on the pinion bearing, and a impact to get off/on the pinion nut.etc etc...

rwhite65 · 08-07-2005, 07:41 PM

You might be able to do it, but Jeff Chambers is giving you good advice. Rear ends are kinda like auto transmissions. We can help walk you threw it, but unless you have someone there to help you in person that has done it before....may not want to tackle it just yet.
Ryan

Jeff Chambers · 08-08-2005, 06:34 AM

You wouldn't believe some of the poor installations that I've had to correct since we opened our shop in May. The very first car to break on our dyno was an 84 Camaro that the kid had installed gears himself before coming in for the dyno sesssion. On the second pull, when I got out of the throttle (and gears went from drive to coast), the pinion sucked back into the differential and locked the rear end up instantly. Tires went from 120mph to 0mph in the snap of a finger and it threw the car right off the rollers. This kid is a technician at a local Chevy dealership (more of shop helper), but he still thought they had been installed correctly. He re-used the pinion nut and crush sleeve and didn't set the pinion preload properly. Result => one really screwed up rear end. Cost him about 5 times to fix it than what it would have to let me install the gears correctly the first time. Damn good thing this didn't happen when he crossed the finish line at the track or he might have tasted concrete!

Other things I've seen:
-Way too much differential bearing preload, so much so that it burnt bearings out in less than 500 miles. Same goes for pinion preload.
- Two crush sleeves stacked together because they didn't set pinion depth properly
- Pinion races that are not square or set evenly
- Ring gears that aren't checked for run out
- Differential bearing caps that are installed backwards
- Parts left in the housing on re-assembly

08-07-2005, 08:56 AM	#1
bigdaddy999 Registered Member Join Date: Aug 2005 Posts: 34	Changing Rear End Gears...HELP I was wondering how hard it was to change the gears in a rear, if the rear is already out of the car. is it just opening up and switching out, or is it alot more complicated than that? If anybody has done this please le me know.

08-07-2005, 09:50 AM	#2
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	Re: Changing Rear End Gears...HELP Take it to someone who knows how to do it right. There's nothing magical about it, but if you have to ask, then you probably don't have the tools to do it right anyways. Not tryin' to 'dis you, but it takes some special tools and knowledge to really do it right. Some folks will just slap them in, but there's no substitute for doing it right. __________________ Jeff Chambers 1990 Mustang GT 10.032 Seconds / 137.5 MPH 14-time Street Warrior World Record Setter CRT Performance 2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH 2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2 "There's nothing boring about a small block automatic shifting gears at 9400 rpm!"

08-07-2005, 03:41 PM	#3
ols0051 Registered Member Join Date: Sep 2002 Location: cent.wis Posts: 203	Re: Changing Rear End Gears...HELP If you have someone able to do the job right, go for it. But if not I wouldn't fear giving it a try. I did mine but have not yet driven the car to see if I did a good job or not. I have had to ask about a ton of things I've done but I have always found good help here. So if you get stumped ask. You will find a ton of people that are very experienced with things like this. You will need a dial indicator for the backlash, and a shim pack. A machine shop to press on the pinion bearing, and a impact to get off/on the pinion nut.etc etc...

08-07-2005, 07:41 PM	#4
rwhite65 Ride Hard Join Date: Oct 2000 Location: Wyoming IL Posts: 1,094	Re: Changing Rear End Gears...HELP You might be able to do it, but Jeff Chambers is giving you good advice. Rear ends are kinda like auto transmissions. We can help walk you threw it, but unless you have someone there to help you in person that has done it before....may not want to tackle it just yet. Ryan __________________ 65 Fastback 91 roller 306, H/C/I AOD-Bauman, PI Stallion, 4.10's and traction loc 04 Grand Cherokee Freedom Edition 79 Ford F-250 4x4 - Restored

08-08-2005, 06:34 AM	#5
Jeff Chambers Moderator Join Date: Aug 2000 Location: Milan, OH Posts: 2,699	Re: Changing Rear End Gears...HELP You wouldn't believe some of the poor installations that I've had to correct since we opened our shop in May. The very first car to break on our dyno was an 84 Camaro that the kid had installed gears himself before coming in for the dyno sesssion. On the second pull, when I got out of the throttle (and gears went from drive to coast), the pinion sucked back into the differential and locked the rear end up instantly. Tires went from 120mph to 0mph in the snap of a finger and it threw the car right off the rollers. This kid is a technician at a local Chevy dealership (more of shop helper), but he still thought they had been installed correctly. He re-used the pinion nut and crush sleeve and didn't set the pinion preload properly. Result => one really screwed up rear end. Cost him about 5 times to fix it than what it would have to let me install the gears correctly the first time. Damn good thing this didn't happen when he crossed the finish line at the track or he might have tasted concrete! Other things I've seen: -Way too much differential bearing preload, so much so that it burnt bearings out in less than 500 miles. Same goes for pinion preload. - Two crush sleeves stacked together because they didn't set pinion depth properly - Pinion races that are not square or set evenly - Ring gears that aren't checked for run out - Differential bearing caps that are installed backwards - Parts left in the housing on re-assembly __________________ Jeff Chambers 1990 Mustang GT 10.032 Seconds / 137.5 MPH 14-time Street Warrior World Record Setter CRT Performance 2001 Tropic Green Mustang GT - 12.181 / 113.2 MPH 2002 Ford F-250 Crew Cab 7.3l Power Stroke - 17.41@77.2 "There's nothing boring about a small block automatic shifting gears at 9400 rpm!"

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