Rear End, How Long Do I Have...Also......

[Kwik_Cutty88]

My rear end started making the classing whirring sound about 500 miles ago, how much longer do you guys think I have before it needs to be rebuilt? From what I can guess it has about 258,*** miles on it and has never been rebuilt. Fluid looked good about 10,000 miles ago. It's a 7.5" 2.56 non posi. Also, my car makes a weird vibration/noise at 4,500 RPM. It sounds like if you run the carpet tool of a vacuum on a hard wood floor. My dad and I assume it's the motor mounts which are rubber and cracked, but the driveshaft was never also balanced too. What do you guys think?

 

[307 Regal]

With all of the action it has seen it's hard to say how much longer it will last (or what brand your vacuum is), but I would definitely start looking for a solution right now whether that be a 8.5" with a posi you find on craigslist or saving up to rebuild your 7.5" with new bearings+races and maybe a new gear set. That way when it does give out, you'll be ready. Or maybe even ready before it gives out so you don't have a towing bill.
And get your driveshaft balanced. Having the rear out is a great time for that since the driveshaft will be basically out anyway.

 

[Kwik_Cutty88]

With all of the action it has seen it's hard to say how much longer it will last (or what brand your vacuum is), but I would definitely start looking for a solution right now whether that be a 8.5" with a posi you find on craigslist or saving up to rebuild your 7.5" with new bearings+races and maybe a new gear set. That way when it does give out, you'll be ready. Or maybe even ready before it gives out so you don't have a towing bill.
And get your driveshaft balanced. Having the rear out is a great time for that since the driveshaft will be basically out anyway.

Yeah i know what you mean, I'll prolly just rebuild the rear end I have now, any rebuild ,kits or gear sets you have heard good things about?

 

[-83MONTESS-]

Check out your u-joints. If you can, unbolt the driveshaft from the rear, and pull back and forth on the input shaft of the differential. See if it has any noticeable play back and forth or in any direction really. Also spin it by hand and see if you can hear anything like gears smacking. With it being a 7.5" I wouldnt bother rebuilding it right now because they can be found on craigslist dirt cheap and with a better gear ratio.

 

[307 Regal]

Nope. I'm not really in the loop with rear ends but I did just finish rebuilding my 7.5" a couple weeks ago. I had never done that before. It used to be a 2.56 peg leg but I put a used 7.625" lsd w/3.73s in it with some new axles. I put in new bearings and races also by a company called Ratech. So far so good. Nice and quiet. I've heard that Timken also makes good bearings. That was actually the brand in my 7.5" and out of the '96 Camaro the used lsd came out of.
As I found out, you do need special tools to do a rear yourself. Dial indicator, press, bearing splitter, axle puller, inch pounds torque wrench, foot pounds torque wrench, impact gun, large impact sockets (an 18mm for your control arms but idr what you need for the pinion/yoke nut), shim kit, special pattern checking paint for the ring and pinion, crowbar would help, just to name what I can remember using. I also used a pretty good DVD as a walk-through, along with good ol' google to find torque specs.
It's pretty involved. Not impossible, but involved. To be honest, I can see why a lot of guys have it done at a shop or just buy another used rear.
As far as gears, I can't really say. The ones I put in were something GM used. I did buy some 3.73s for my 2 series open diff but I never used them since I got a deal on that Camaro diff and gears.

 

[Evan11]

Some 85w140 diff oil might calm it down some.

 

[Kwik_Cutty88]

Alright guys, I need some help on this. I checked craigslist and didn't see any decent 7.5 or 8.5's within 200 miles of me. So I scowered jegs for a rebuilt kit/the parts I would need and I am at a complete loss. I would like to do a full rebuild, and maybe a posi and 3.08 or 3.23 gears. I got lost in all the clearances, and series, and all that sort of stuff. If someone could give me a quick lesson on what I would need/ how to go about looking for it.

 

[Kwik_Cutty88]

 

[307 Regal]

For a full rebuild, you'll need a bearing kit which should at minimum include 2 bearings+races for your diff and 2 bearings+races for your pinion gear. When you get the bearings and races, don't mix them up as they could be matched sets. You'll also need a shim kit for your carrier and pinion, axle bearings and seals (which if not in your bearing kit can be bought through Moser), a new pinion seal, *a pinion nut, a crush sleeve (I'd get 2 in case you mess up the first one), new ring gear bolts if you change gears (left handed thread), a new pinion shaft retaining bolt if you're using a used diff ( http://www.summitracing.com/search/part ... 0Fasteners ), new diff fluid of course, **limited slip additive if you go to an LSD, and if you do change carriers then make sure the spline count is the same on your axles or you'll need new axles and studs. Just about all of this stuff can be found through places like Summit. Here's a list of bearing kits:
http://www.summitracing.com/search/part ... /gm-7-5-in
http://www.summitracing.com/parts/rat-3001k/overview/

*The pinion nut (found on the outside holding the yoke for your driveshaft) is dented so it won't easily come on and off. It's guaranteed that you'll need to take it off 2-3 times minimum while setting pinion depth (your gear pattern) and installing a crush sleeve. I've noticed that after a while this will really mess up threads. You can get a new nut cheap but it's not so cheap to replace a pinion. Take your pinion gear to a hardware store and find a regular nut that will easily go on and off. Use this for your setup process to save the threads. For final installation, use the new dented nut.

**There are conflicting reports as to whether or not this is necessary, but I just used it for good measure.

One of the best things you can have for your first diff job is a good walk-through and a laptop near by to play it / use the net. Here's the one I used:
http://store.boxwrench.net/Rear-Axle-Di ... _p_61.html
It's very in-depth. Every rear end model has different specs so you won't be able to follow it to-the-letter (including backlash and some torque specs) but I found it to be a great source of understanding and confidence. Just take into consideration that they use a pre-cleaned demonstration unit and we're working on rusty units with 6 digit mileage.
P.S. Don't get the DVD by Richmond. My dad says it pales in comparison to the one we used.

 

[86 Grand prix]

I bought the complete Richmond bearing kit from Summit, it comes in a couple of different ways. I got the complete kit with the axle bearings and seals. I picked up a Auburn LSD with 3:42 gears from a 4th gen Firebird at a pull a apart for $45.00 and ordered new Moser 28 spline axles from Summit.