Recent posts have prompted this response for your consideration and comments.
Once I have the carrier and axles bolted together with the mandatory brass thrust washer between the axles, I bolt the left axle housing on my stand in its vertical position. Then the two steel washers and a new bronze thrust are fitted and the axle/diff assembly is dropped into place.
Next the other two steel washers and the bronze thrust are stacked in place and the right axle housing lowered into place. Given the bronze thrusts need to be dressed down, there is a gap between the two axlehousings.I square this gap up with three of the axle housing bolts finger just tight and measure the gap between the housings.
Given a gap of say .040" I need to remove .042" from the bronze thrusts to give a couple of thou. running clearance. I would take .015" from one and .027" from the other. This will leave one thrust some .012" thicker than the other.
The idea is to give some flexibility when trying to set the gear mesh. Having two different thickness thrusts allows them to be swapped from side to side to shift the assembly within the housings. It would be nice to have some variation in the thickness of the steel washers too, but .003' seems to be as much as I can find in originals. Perhaps adding one or two steel shims of different thicknesses before measuring to machine the bronze thrusts would do the trick. They could then be swapped too.
So far this procedure has allowed me to get the pinion gear/crown wheel mesh spot on using both original gears and a couple of 3:1 sets.
Allan from down under.
Sounds like a great method - I did something similar as far as I can remember
Allan, I find that the brass washers are usually thicker than needed so instead of dressing them down I search my pile of steel washers for thinner ones. I must have a couple of hundred steel washers from old tear downs and they vary in thickness quite a bit. I even have some thicker ones that I assume must have been available in the day to make up adjustments without shims.
The brass thrust washers I have are also too thick. When I assembled the axle housings there was a good 1/8 inch gap!! I don't have thinner steel washers to switch around to reduce the distance, so I guess I'm forced to have them milled to size...
Why are they too thick in the first place?? Very frustrating.
MIKE: Check the hole in the brass washers. The last ones I got the hole was TOO small to let it go over the diff housing. The whole batch I got is that way. You need to check that before you start cutting on them. Thanks, Dan.
Hey Mike - you can have them milled but I got a flat steel block, put sand paper on it, then the bronze thrust washer, then used an electric random orbital sander on top of that. I mic'ed it in 4-5 places around the outside to start, then again after I sanded it a good minute on the stop watch. Then I'd flip it over and do the whole thing again and then make sure it was pretty even everywhere. 10 to 15 minutes tops to assemble, make an educated guess on how much to remove, sand the washers, and reassemble. I ended up sanding mine twice. That may be a lot easier and more reasonable then taking them to a shop to have them milled (possibly more than once) when the only way to know if they're really right is to bolt the housings together and see how the ring gear turns.
I used 150 grit to really cut through, and then 400 to polish and smooth it out a bit.
Dan & Seth, good info. I'll check out both options for sure. Thanks for the feedback!
It's true that the bronze washers are usually a bit too thick. However, they should not be 1/8" too big, (1/16" each). Most likely, one or more of the steel side washers has dropped off its locating pin during assembly and caused binding. This is a very common thing. Before assembly, use grease to "glue" the side washers in place.
Thicker brass washers help make up for worn housing. I find it is easier to work with. I machine them down on the lathe and finish them off with a file and crocus cloth. I think the machining of the earlier housings was not very precise so having the thicker brass washers allows for adjustments of the differential. I have rebuilt a lot of rears and the later ones are usually close on with stock parts but the earlier ones are all over the place and require a lot of adjustment.
I used grease to glue the steel washers in place but they could have slipped during assembly. I'll check it to be sure, thanks.
Seth, I use the three finger tight bolts to get the axle housing sitting square, so I can then measure what needs to come off the thrusts. This removes the guesswork/trial and error multiple fittings. It also puts a figure on the amount needed to be removed so I can manipulate where it is best removed.
All of this is done prior to any fitting up of the torque tube assembly.
Allan from down under.
Allan, The gear mesh should be adjusted before you fit the right housing. That is the last thing you do before final assembly. Read the book.
Glen, once I have the centre settled in the housings, I take the right housing off again to set up the pinion mesh. By making the thrusts different thicknesses, and by juggling them and the steel washers from side to side as needed, I have been able to get a correct mesh almost every time. You are correct. The gear mesh is set before the right housing is fitted.
By getting the shim/steel washer/bronze thrust stack installed so the diff is fitted at the correct clearance beforehand, setting the pinion mesh up is just a matter of swapping things around in the left housing to set the mesh. Then the rest is simply added to the other side on assembly. This saves having to machine the left thrust to get the correct mesh for the pinion and then having to go through the same procedure on the right to get the correct play in the whole assembly.
It works for me. Others may/may not like the idea.
Allan from down under.