vbMike

iTrader: (2)

Okay. I'm going to attempt to install a set of gears in my 9 bolt. I have 3.27 in there now and have a set of 3.70 to put in. I need to get an install kit but I'm not sure which one to buy. Install kits appear to be different from vendor to vendor and even the same vendor sometimes has 3 or more different kits from basic to all parts included. I've looked around on the msg board but can't find any good guides. I've rebuilt and installed my T56 so I think I should be able to handle this 9 bolt. Anyway I have several questions.

1. What vendor do you recommend buying an install kit from?

2. What parts are needed (specific) - Bearing, seals, shims, etc... I remember reading about replacing the axel bearings but it sounds like a pain so I might not do that. BTW, my car only has 27,000 so there may be some parts that just don't need replaced.

3. Do any install kits come with instructions?

4. I need to know specification such as torque settings, preloads, backlash, etc...

5. What special tools will I need. I know I need a dial indicator. What kind did you guys use and where did you buy it. I hear that a dial style inch pound torque wrench is recommended to check pinion bearing preload but I can't seem to find one. Is this tool needed or not, if so where can I get one? I also hear you need a slide hammer to remove the axels, can you make due with something else or is this the only way they are coming out? Any other tools?

6. Correct me if I miss speak but I think there are five things you need to check. Pinion depth, pinion bearing preload, carrier backlash, carrier bearing preload, and tooth pattern. I have a guide somewhere showing how to read the gear tooth pattern and I think I have the backlash thing figured out. Basically install as many shims as possible to make the carrier snug. They move shims from the left side to the right side to increase backlash or from the right to the left to decrease back lash. Once the backlash is set how do I know how many more shims to add to obtain the correct carrier bearing preload?

I'm a little confused about setting the pinion depth. I've hear that you can use the stock shim and that is close enough as long as you have a good pattern. Others say there is a special too to purchase to measure pinion depth. Is this needed and if so where do I get the tool.

I've also heard that it is better to use a solid pinion spacer instead of a crush sleeve. I'm a bit confused about setting the pinion preload. Correct me if I'm wrong but with a crush sleeve you first figure out the pinion depth and then install the bearings and crush sleeve and tighten the nut and continue to tighten until the proper preload is obtained. If over tighten you have to start again with a new crash sleeve. With a solid pinion spacer you install the bearings and spacer with shims and then tighten nut until tight and then stop and check preload. If more preload is needed you decrease the number of shims and if less preload is needed you increase the number of shims.


7. I guess the big thing right now is trying to figure out what parts to replace when I have it apart and what install kit to buy. This web site has 3 install kits with various parts but I'm not sure which one to get.

http://ratech.stores.yahoo.net/79bogmax.html

Would I be better off just buying the parts I need so I don't end up getting parts I won't use like ring gear bolts, crush sleeve, etc..

The install kit on this site (one in the middle) seems like it has everything. Anything that is missing?

Any help here would be appreciated.

88bracketT/A

Look through this thread. Alot of good info. Most of your questions are answered.

https://www.thirdgen.org/forums/faq-...now-about.html

vbMike

iTrader: (2)

A great post but I've already read it.

vbMike

iTrader: (2)

This relates back to the what install kit to buy. What is the recommendation on bearing? Sould none, all, or only some bearing be replaced? Which ones. My axel only has 27,000 on it. I've read that some bearings will be runied when trying to removed them, which ones?

88bracketT/A

If you have the correct tools you can do it without damaging any of the bearings.

The side bearings will not have to be removed so if they are in good condition you won't have to replace them.

The outer pinnion bearing will be removed when you tap out the old pinnion gear and should not do any damage to it.

That leaves the inner pinnion bearing. If you have a pinnion bearing puller you can get this off the old pinnion without damaging it. If not just by that bearing and press onto new gear. If you go this route you will also have to replace the inner race. The cost of the new bearing and race is much less the puller so if your not going to be setting up to many rears just buy the new bearing.

Also another trick that might help you is to take the old inner race and grind the outside of it a little to make a smaller dia. You can then use this as a dummy bearing to get your pinnion depth set. Once you figure out the correct shims install them with the new race. This way you don't have to beat the new race in and out each time you change shims reducing the chance of damaging it.

Hope this helps you out.

vbMike

iTrader: (2)

Okay so I should be able to reuse the carrier and outer pinion bearings. If I can get the only inner pinion bearing off I can also grind that out to use as a setup bearing along with the old race.

How do I go about setting the pinion depth? I’m lost here. Obviously, I should start with the old shim and see how it looks. Is there anything to measure for pinion depth or is it just checked by looking at the pattern?

What about the preload? How do you check that for the pinion and carrier?

88bracketT/A

Looking at the contact pattern is only a final check not for setting the pinnion depth. You need to measure the pinnion depth with a gauge of some sort. You can either purchage a pinnion depth gauge or you can put a strait edge accros the side bearing cap pads and then measure from the strait edge to the face of the pinnion gear and subtract the width of your strait edge this will be the pinnion depth. Then add or subtract this from the number scribed on the end of the pinnion gear ans that is the amount of shim to add or sutract.

vbMike

iTrader: (2)

Okay, I have a used gear set that I am putting in and there is no number on the end of the pinion. Unless I just can't find it.

n8sz28

rather than posting a new topic is was wondering if someone could briefly explain the difference in the clutch posi unit used in 10 bolts and the cone type clutch unit used in the 9 bolts. which one is stronger. also will a 9 bolt, bolt directly up to a 85 camaro? wasn't sure if the driveshafts were the same.

player 88

iTrader: (2)

I did exaclty what you did the psring, went form 3.27 to 3.70. It wasn't very hard. get the FACTORY manul and follwoit as well as the instructions for the pinion depth. There in no pinion depth gauge for a 9 bolt that I know of. I measured from the carrier bearing cap mating surface. this is the center of the ring gear. I has to add approx. .004 to original shi wit the 3.27.

I then used a new crush sleeve and torqured the pinion nut util I had the approx. the same roational force that I had with the original 3.27 pinion. I used a fish weighing scale to measure pull force.

I then loaded the carrier in with the oroginal thick ness pack of shims less the preload amount. It is in the factory manual. then measure the back lash. adjust the shims to set the back lash. If you remove shims on one side you add them back onthe other to take up slack. i.e. no side-to-side carrier movement. Once back lash is set then add then check the tooth pattern. if this OK then add the preload shims to each side and button it up. It not ad or substract shims to the pinion bearing or between the rear pinion bearing race and differential housing. NOTE: the 9 bolt pinion depth can be set by adding shims between the rear race and housing. that is how mine was set up and all 3 spares differential I have were done.

Just think what you are doing and do the math to calculate the pinion depth. and the shim required.

specs from the factory manual:

ring gear backlash .004-.007

I used a Motive Gear full install kit and gear set. they both come with instructions.

good luck

vbMike

iTrader: (2)

Where did you get this FACTORY manual from? Would you want to make me a copy of the relevant section???


I like your idea about using the fishing scale to measure the rotational resistance of the pinion! The only problem with this is that you are measuring the pinion bearing that are currently installed and worn in. This would be fine if you reuse the bearings. However, if you replace the bearings the new ones should be setup tighter. If you setup new bearings with the same preload as the ones that were removed they the new bearing may become loose/sloppy as they wear in.

The factory manual says the backlash is .004 - .007? That seems really tight. I've read that it was supposed to be .006 - .010. Do your gears wine at all?

If I am putting in used gear should I go with the spec or should I increase or decrease the backlash. For example, when reusing pinion bearings the preload is supposed to be less than what a new bearing would be set at, about half. I wonder if used gears should have more backlash since they are already broke in?

vbMike

iTrader: (2)

Player 88,

I was a bit confused about the setting of the pinion depth. So can I take a measurement of the stock pinion from the flat part of the pinion head to say the outer housing or bearing cap?. Then use shims to adjust the new pinion to get the same depth? Is that basically what I need to do? Does the ring gear play any kind of a factor in setting the pinion depth?

TransAM Joe

iTrader: (6)

First off I would get the RATECH complete 9 bolt install kit and replace all bearings, races and seals. I would also put new axle bearings and seals on since your in there. All of this is much easier if you pull the whole axle assembly out of the car and it not that much work and beats working on your back reaching up into the housing, plus cleaning it will be much easier.

First make sure your carrier including posi cones are in excellent condition because now is the time to correct it if it's not. As far as performance upgrades really besides what you are doing is going with 31 splined axles but that requires changing the carrier. I would add the TA Performance rear girdle and get the ARP Stud kit, a big help.

To set the gears up properly this method has always worked well for me and I've set up quite a few gear sets over the years:first make sure you have a inch lb dial torque wrench, if you don't then get one and a magnetic dial indicator. To start set the new gear set up with the original pinion shim and carrier shims and put the pinion nut on WITHOUT the crush collar for now. Check the backlash on the ring gear and set it to .006-.010 inch. YOU MUST GET THE BACKLASH SET PROPERLY BEFORE YOU CAN GET THE CORRECT PINION DEPTH!! If the backlash is not within spec then take shims from one side and add to the other till it is within specs. Now take your marking compound and paint three or four teeth in two different spots and spin the ring gear a couple times. NOW THE PATTEREN MUST BE CENTERED FROM FACE TO FLANK EVEN IF A HEEL TO TOE PATTERN IS NOT IN THE CENTER: this always indicates correct pinion depth. If necessary add pinion shim(s) to get a centered face to flank pattern, this may take a few tries so don't get lazy. Now take it all back apart and add the crush sleeve on the the pinion gear and torque the nut down to achieve a 12-15 inch lbs. resistence on the preload (for a new bearing) If it's a used bearing more like 6-7 inch lbs. Not too hard just time consuming, but you will have a quiet long lasting gear set.

vbMike

iTrader: (2)

Thanks for the reply Joe.

A couple questions. Where can I get a inch lb torque wrench? I can't seem to find one.

So you adjust the pinion depth the center the pattern from face to flank. What do you change to adjust heal to toe pattern?

6speedIROC

iTrader: (3)

Try KD tools for an in-lb beam style. Or Snapon has the dials, but they are $$$. Note that the 9 bolts had at least 2 different size main pinion bearings. Make sure you get the right one in the kit, or you can buy it separately at a bearing shop.
I can email you the factory manual in pdf. Send me your address.
Shim your posi while you're in there.
FYI 9 bolts use tighter backlash than other axles for some reason...check the manual.

TransAM Joe

iTrader: (6)

you cannot adjust face to flank and heel to toe independently. Just worry about getting the face to flank centered on the gear and use the charts posted as acceptable wear patterns. It all depends on how carefully the gear set was manufactured. In my experience the $200 gear sets usually don't have a perfectly centered heel to toe like the $600 gears sets almost always do.