alloy

iTrader: (16)

I've got a used 3.42 rear out of a wrecking yard and I'm putting a zexel from SLP in it along with 28 spline axles. Before pulling the carrier and ring gear, the backlash was .006 in one spot, and .004 pretty much everywhere else. I've got it back to that including preload, but the book calls for .005 to .009 backlash on new gears. Should I try to get a little more backlash than the .004 on this used gear set?

90Formula-X-F

Ideally when installing used gears the exact wear pattern and backlash would be perfect. Since you seem to have the #'s from what they where before, I guess another rear end ? use all the old case shims and see if it comes up like it was before. if so run it.

Ohh and the answer to your question is if the backlash was 4 - 9 then the used gears would be set up to 9, atleast thats what the little books I get with the diff overhauls kits say in them.

alloy

iTrader: (16)

Guess I should have been more specific. All I did was pull the carrier and ring gear out of this rear, and put the used ring gear on the zexel and put it back in. The pinion wasn't touched.

I tried using the original shims and got perfect backlash, but zero preload. So I got a set of those stackable type shim packs that use two thick parts, then sandwich smaller shims between them. If I ever do this again, I'm going to get regular shims. Took forever to get the backlash to the specs I mentioned with these shims. The assortment of shims included in the kit isn't the best.

4L60bliss

You want the backlash to be the same as what it was before being pulled. The idea is the set them up exactly as they were. Backlash does effect pattern.

90Formula-X-F

If you have the same backlash as you had before and your pinion dept hasn't changed then it should be perfect but since the carrier is diffrent it packs diffrent side clearence and there for analize the pinion pattern to be sure that it looks close to where it ran before. If so your in. Those little thin shims do s**k.

Chris89GTA

iTrader: (2)

well... i am in the process of re doing my rearend... i had the 2.73s on the open diff setup and absolutely shattered my pinion... so i bought the zexel from slp and a set of used 3.42s a buddy of mine had... and let me tell you... it has been a pain the the *** getting that thing set right... i have tried 3 diffent pinion shims as of now and will probably try again tonight... we are close to getting it back together... only real problem is we have a great pattern on the drive side of the ring gear... but my coast side is way too deep... so i gotta move the pinion back a little more and play with it some... but onto the backlash q man... from what i have read on using used gears... if you are anywhere between .005 and .010 you should be alright

alloy

iTrader: (16)

Well everything turns over pretty well. Takes a little more effort to turn the pinion by hand, but there are new bearings on the carrier with preload. The old carrier didn't have much preload, and the stock thick shims had spun and worn about .0005. I was going to use them, but I needed some .004 shims to get some preload on the new bearings, but couldn't find any anywhere. So bought those shim pack things (they suck) and had it together and apart about 7 times. I don't have any marking compound, but can get some. I guess it's not a bad idea to check the pattern. Couldn't hurt, and could help big time if the pattern is off. I'll try to get some compound today and post about how the pattern looks.

I guess this is good practice for me. I've got a 97 astro van and the rear howls on both power and coast. So it will need a new ring and pinion for sure. And, since it will be apart, might as well put an SLP zexel in it if it has the right gears to do so.

Chris89GTA

iTrader: (2)

yeah its a good idea to check the pattern... but you will find that it is really hard to get a perfect patter with used gears b/c they already have a wear pattern on them... there a couple of links i will post later that have contact pattern diagrams for you...

the reason my stuff broke was b/c the previous owner had changed the pinion seal and forgot to put the washer back, and to locktite the nut... so the nut walked itself off the pinion and the pinion was flailing around in there but it will better in the next day or so

oh yeah... are you talking about the preload on the pinion bearings in that last post?? what did you torque the pinion nut to when you put it on... cause with new bearings you need to torque it to 20-25 inch/lbs to get the correct preload!!

Chris89GTA

iTrader: (2)

here are those links i told you about dood

http://www.precisiongear.com/pgtech_contact.htm

http://www.drivetrain.com/ringpinioninstal.html

http://www.ring-pinion.com/foursettings.shtml

http://128.83.80.200/taco/r&p.html

http://www.tpub.com/basae/129.htm

90Formula-X-F

Actually you can pattern it with some white grease and should be able to see it ok.. When turning the pinion with the new bearings you'll find it hard to turn also.. it's normal and will wear in. I think you got it all going on except the test drive.. 8-)

alloy

iTrader: (16)

Chris, All I'm doing is pulling the carrier and ring gear, putting a zexel in, new bearings and races on the carrier, and setting the backlash. I didn't do anything with the pinion.

I had a kind of famous local engine builder over to the shop today, and he brought some marking compound and looked at the the pattern and said it looked really good. Got about the right amount of preload on the carrier bearings, but need to increase the backlash to.008 from the look of the gears. He says the gears look very good buy the way. He's been doing this for many, many years and knows what he is doing. He used to build engines for Harry Gant when Harry was winning. When AC was building engines for Harry, they called Harry "Mr. September" beacause he was unbeatable in that month. Geez, does anyone but me old enough to remember that name? Harry Gant?

Anyway he also told me about a spreader he has that you put in the two holes on each side of the housing and it spreads the housing enough that you can drop the shims in without forcing them in. I'm going to go borrow it tomorrow morning. So other than increasing the backlash, I think I'm about there. Now just have to put it in the car on Sunday. I would do it Saturday, but there is a swap meet here, and also a car show at another location. I can't miss these!!! I can't wait to see what the 3.42 and a "working" posi feels like verses the 3.08's and useless Auburn unit.

Will keep you all posted.

84305HO

Just a quick question, but what is the
"right amount of preload on the carrier bearings" ? And is this set by the shims also ?
I will probably be doing this same mod;
reusing 3:73 gears, and replacing the
old posi with Zexel Torsen and adding some new 28 spline axles.

alloy

iTrader: (16)

Yes the preload is set with shims. The book says to get the proper preload, then add a .004 shim to the right side. I set my used gears for .008 backlash. But, if you are reusing the gears in your rear end, check your backlash before pulling it apart, then duplicate that setting. Check the backlash in about 4 places around the ring gear. Mark the places with a felt pen and get as close to those settings as possible when you put the new carrier in. Then gears develope a pattern when they run together and it's best not to change this pattern. My backlash varies about .0015 around the ring gear. From about .007 to .0085

Do yourself a favor, get some shims or the shim pack setup I had before trying to install your gears. I was hoping that I could use the stock shims. The stock ones were perfect for backlash, but had zero preload. And you have to have preload on these bearings. You also can get a cheap magnetic base and dial indicator from Enco manufacturing to check the backlash with. www.use-enco.com to check your backlash. They have a set on sale now for $19.95. Part# BA625-1340. The price is good until 12-31-02. Or you can call them at 1-800-965-5857.

I'm glad I took the time to do this right. The "new" (used) rear that I put in is quieter than the one I took out. Just be prepared to pull the carrier multiple times to get it right.

Also, the zexel from SLP will come with bearings installed on it. One of mine was good, the other wasn't. So I replaced one of the bearings and both races. If your bearings are good, then just buy the races. The bearings on the carriers from SLP are so new you can reuse them. Just don't, and I repeat don't be tempted to reuse your old races on the new bearings.

My old races are a Hyatt Clark #LM501314. They were about $8 each. I had to special order them, but got them in one day. If you have to pull the bearings from the zexel, take it to a machine shop and have them do it. They are tough to get off ,and I own a machine shop and had a heck of a time with the one bearing.

Anyway, now I have to pull the back of my T5 apart to change the speedometer drive gear. Great fun!!!!!