I am currently in school for automotive technology and am currently taking Drivetrain. Since I've been in class I've been planning my projects for the spring, one being that I'd like to beef up my rear end, and I'd like to start that by upgrading to a 10-bolt, and getting better gears. I'm sure I can figure out how to change it as I go, especially with my classes, but I'm at a loss as to what I need to buy, and from where. Would I be looking for a 10-bolt differential "case"? if so what changes will I have to make otherwise? Like new axles and such, if any. I read through the 10 bolt rear sticky and couldn't find the info I need, so I figured I'd try a thread.

 

The 9-bolt and the 10-bolt are 2 completely different models of product, made by 2 different companies on 2 different continents. NOT ONE SINGLE PIECE inside them interchanges. Not gears, not axles, not carriers, not bearings, NOTHING.

So you can't really turn one into the other except by the magical 2-step method involving a 3rd item in the middle.

Step 1: Sell rear end you don't want.

Step 2: Take the cash you got from Step 1 and use it to help buy the one you do want.


The 9-bolt is marginally stronger than the 10-bolt. It main issue is parts availability. I wouldn't consider going from a 9-bolt to a 10-bolt an "upgrade" if all else is equal. The benfits of swapping to a 10 bolt come when you get a 98-up (LS1) one with good gears, good brakes, and a MUCH better posi than was in any of these cars.

 

Unless you get a 98+ 10-bolt, it isn't an upgrade. Even then, there is still the aspect of bolt-in axles vs the c-clip retainer. Convert the 98+ to a bolt-in axle retainer & then, IMHO, it is a complete upgrade.

 

In that case I'd be happy putting a different set of gears in it but all the ones I find online are for a 10-bolt. Any suggestions on where to purchase a set of gears for the 9-bolt?

 

http://www.9bolt.com/gearsets.html is the only place I know of, although it was my understanding that some components of the 9-bolt are still in use to this day, in Australia. That makes some sense, since Australia is the origin of the 9-bolt.

 

Awesome that's exactly what I'm looking for. I need to find out what my current ratio is and see if I need a new carrier, then I can start buyin and throwin it in, thank you very much. Been sitting at the computer for hours trying to figure something out

 

I wouldnt plan on installing the gears yourself.

Definately sounds like you will need to pay someone that knows how to set them up correctly.

 

Installing gears isnt that hard, but you do need a lot of tools. A lot of those bolts and parts inside differentials are in there pretty f'in tight. Power tools are a must for some of it. Just getting the pinion gear out of my 9-bolt was a major PITA. Mushroomed the hell out of it trying to hammer it out. Ended up having to take the rear out of the car just to get a full swing on it that was good enough to dislodge it. Had to use a big honkin heavy duty electric impact wrench I rented from the autoparts store for some of it. Then you need a press to remove the bearings off your old pinion gear and replace it onto your new one. I had one bad carrier bearing too, so I had to replace it so that bearing ahd to be pressed off and a new one pressed on too.

Just in case you're interested - bad bearing:



So you can't just assume everything inside of it is fine. ratechmfg.com sells some really nice kits and parts and I've always used them for my 9-bolt setup stuff. They've got bearings, shims, pinion bolts, ring gear bolts, seals, etc. They also have the solid pinion spacer which makes the setup a lot easier and will make your diff a little stronger.

Then it's really not so bad. You need some calipers/micrometers... measure the thickness of the shims on each side of the carrier (you have to pay attention to which side is which, very important) and then just match it with your new shim set that you will buy from ratechmfg.com and then you will match your new solid pinion spacer to the old crush sleeve's thickness using the supplied shims with it. Then you match your old pinion gear's pinion depth. Just use a straight edge across the face of the diff and measure as well as you can down to the pinion gear. Try to match that as close as possible with your pinion depth shims on your new pinion gear.

From there you need to bolt your new ring gear to your carrier and get your factory shims in place, pop it in, check the pattern (with gear marking compound) and backlash (with a dial indicator + magnetic base) and backlash to get your starting point. From there you can tweak things around to get them where you want. Moving the ring gear away from the pinion gear from left to right will increase backlash and effect the pattern. Moving it towards the pinion gear from left to right will tighten the backlash and effect the pattern. If moving it left to right doesnt get the pattern correct with the backlash in the right range, then make a small adjustment to the pinion gear's depth and start with factory carrier shims again, and move the carrier from the factory location and then left and right and see if you can get the pattern right. It's trial and error but truly it's not awful. The actual gear setup itself is the easy part.

Just write down where you started, try to keep your carrier shim thickness of the L + R side equal to stock... so you take a little out of one side and move it to the other, make one adjustment at a time.... Eventually you'll get it pretty close. As long as the pattern is good and your backlash is around .007-.010 you're good to go. All the shim play is just to get the wear pattern and backlash correct. You will have pinion shims (that replace the crush sleeve along with your solid pinion spacer - this is a worthwhile investment, very cheap, and makes it a lot easier to install too) and carrier shims on each side to move things around and that's really all there is to it.

You're supposed to use an inch/lb torque wrench to measure some stuff...

Its not easy but it's not rocket science either. I skipped over a lot of things, so if you want a more in depth read, go here:

http://www.corral.net/tech/drivetrain/gears.html

You can substitute an inch/lb torque wrench with feel if you need to, it's not that hard to tell if it feels wrong, but it's not the "proper" way to do without it. I didnt bother with it.

Also, several companies make gears for 9-bolts, just look. The only aftermarket ratio available is 3.73/3.70, though. If you want 3.27's, 3.45's, or 3.90's you're SOL unless you buy from Australia or buy used. I got my Yukon 3.70's from biggearhead.

Hopefully I gave you enough of a feel for the job that you get a good idea of whether or not you're able to handle it. But the gear setup itself is REALLY not as bad as it's made out to be.

 

Thank you very much for all that info. I do know how to swap the gears though, and I have access to all the tools. I just don't know if I want to stick with this 9 bolt. I don't think this whole slip resistance cone BS or w/e they're calling it is even worth having in my car. And I'm not going to try and change my carrier of the rear end I don't even like just to get better gears. Looks like i'll be saving for a new/different rear end.