What is the correct thickness of the thrust plate washers in the differential?
The necessary thickness varies based on the tolerances of the axles halves and the assembled differential. I put my axles together standing on end and then measure the gap between the axle housings. That gives you an idea of how much to remove from the two bronze plates.
This is my first rear end rebuild so there is much to learn. I do not understand what you mean by "removing from the two bronze plates".
When I look in the catalogs they speak of a "precision ground for the correct thickness" of the thrust washers. That is the number I am looking for. I am trying to determine if I can reuse the thrust washers I have or do I need to replace them.
I understand there are shims to use to account for wear and tear.
John, If your thrust washers are the original babbitt, you should replace them. If they are bronze, they should be ok unless they have cracks or other imperfections. This topic has been discussed on this Forum many times and if you search on "Topics" or "Keyword Search" you will find those threads.
Adding to what Keith said
Re-use the four steel ones that have the two dowel holes in them if they appear serviceable with no gashes or bends. And if you do not have two bronze plates you need them.
Right. I have 2 new bronze thrust washers and it is the steel ones that I was inquiring about the thickness.
PS: I appreciate everyone's input.
No one can know too much!
Sounds like you may be flying blind. The MTFCFA axle book by Glen Chaffin is the first rear end part you should buy. It gives you the measurements.
I have the "Bible" and have borrowed Tinkerin' Tips Volume II from a T Bubba friend but "Flying Blind" aint far wrong!
Not sure I agree with all the Tinkerin Tips, at least some that I've seen. Glen Chaffin's book is a better investment.
John, if the housings are good on the surface where the steel washer is held in place by the two pins and the carrier is not worn, you place one of the new bronze washers on the thrust side and the ring and pinion clearance should be correct. Devise a way to hold the housing upright and install the housing washer, the carrier washer and the bronze washer so they will stay in place. Install the carrier into the housing with both sleeves and both bearings installed in the housing. Now install the driveshaft with the pinion gear to the housing. Check the clearance. If it is too big, add a shim between the steel washer and the carrier. If it is too tight, machine away the bronze washer a few thousandths at a time until you have the correct gear clearance. Remove the driveshaft and pinion gear setup. Then with the housing still in an upright position, add the carrier washer, bronze washer and housing washer to the up side of the carrier and install the right side housing from above the axle. (Incidentally, I don't replace the little pins in the housing until I have the clearances set on the washer. Makes it a lot easier when checking the clearances if you don't have to have the washer on the pins.)
If the clearance is too small it will keep the housing from setting all the way down on the left housing. If it sets down tight, get a little flashlight and a long, bent feeler gauge. You can see in the hole, put the feeler gauge in and see if you need a shim. You should not have more than .005 clearance between the washers, etc. Makes it a lot easier to do it this way and you have the weight of the housing holding everything together. I put a few bolts in and tighten them up to make sure there is a little clearance and it is not locking up so it won't turn. I prefer that there be just the slightest bit of drag, which means there is virtually no clearance at all. If you need a shim, it is easy to put one in. If it is too tight it is easy to machine away a bit of the bronze washer. If you search back I posted an easy way to thickness washers with a drill press and piece of angle iron awhile back. Lifting that housing up and over the end of the axle is a pain but it will reward you in a good fit when you are done. After you get your clearances what you are sure are correct, lay the housing assembly down on your bench and try to move the axles back and forth. If you can feel any movement at all there is too much clearance. You can't feel .005 or less.
When you put the carrier together you should have made sure the axles cannot move more than a few thousandths by installing that fiber washer between the ends, maybe two fiber washers to make sure nothing can move. (I use PTFE 1 inch bar stock and machine a washer the correct thickness for each rear end instead of using fiber washers) You can also use brass in there.
I don't use the paper gasket, I use copper bearing gasket maker by Permatex, smear it about half an inch on either side of the parting line before final assembly and let it set up for a day before I put grease in there. Make sure you wipe down the inside of the carrier with lacquer thinner so the gasket maker will stick.
Also, before you put the right side housing on, go just behind the boss for the third parting line bolt and drill and tap the housing for an eighth inch pipe plug. Makes it a lot easier to change the diffy lube down the road. Use a brass plug and it won't leak.
Now to your original question. New bronze washers are .200
New steel thrust washers are .088.
To follow up a little, I guess you know that the adjustment of the clearance on the ring and pinion is with a couple paper gaskets between the housings and the pinion bearing carrier. It's surprising how much difference a gasket can make. My rule of thumb is that if it takes more than 3 gaskets to get clearance I machine the bronze washer down a few thousandths to get the necessary clearance. Your mileage, opinions, methods and results may vary. I agree, get a copy of Glenn's book, it's a good investment.
Based on my experience, there a far more problems with setting the ring and pinion up too tight than too loose. .010 - .015 seems to work well. They are just straight cut gears and are not as critical as hypoid gears.
Thanks Steve and Stan.
Steve... see you tomorrow!