Rear Diff Rebuild Q's (1 Viewer)

brownbear

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So all my jobs are slow... But over the last little bit I pulled my rear diff to rebuild it. The reason I am doing it was I felt in the clutch and drive train to me, back lash. Also I had excessive noise in the drivetrain.

Prior to stripping the diff I took the measurements. I think I have .017 of back lash. Run out of the gear did not move more than .003 on my dial indicator. But it wasn't easy to check with indicator bouncing along.

Pulling the drive pinion. I noticed some wear in the splines. There is no mention in the FSM about acceptable spline wear between the drive pinion and the companion flange. I see a little movement together. Like 1-2 thousands of an inch. But Its hard to measure.

Please have a look at these pictures and let me know what you think. My picture inside the companion flange isn't clear. It did not seem as worn.

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RustyNailJustin

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This is in an FJ60? If so someone put 4.11 coarse spline ring and pinion in it or complete 3rd.
Depending on what you are doing with the truck... The coarse spline is much weaker than the later fine spline.
Looking at your pictures and measurements you can run what you have but there is much more slop in the coarse spline version.
.017 back lash is a lot. You can tighten that up a little get closer to .010 or so.
If it were mine I would swap gears to fine spline pinion.
 

brownbear

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@RustyNailJustin yah it's an 84 BJ60. And they are 4.11 I installed, I used complete 3rds about 15 years ago. I installed them as is and not overhauled. I got them from another cruiser owner. No idea what they came out of.

Now I am trying to rebuild them. I am guessing they are older than my truck then?

SO another issue I found today. I removed the bearing race for the large pinion bearing out of the carrier and there was a shim under it. The FSM doesn't show this shim. Also on my pinion under the big bearing it doesn't seem to have a shim either. So it looks like it was shimmed under the race, not the bearing to get the contact patch. It has a toyota logo on the shim and the markings .40 I did damage this shim with a punch.

My kit I have is from US standard gear, with all koyo bearings. It has shims that are the same size as the one I removed. So I am guessing this is another way to set up, rather than taking the pinion bearing on and off as you test the pattern. What should I use for a starting shim thickness? I'm not such a fan knocking a race in and out for setting up, but it might be easier than the bearing.

I also did not have a crush spacer in my 3rd when I took it apart. It had shims. My new kits comes with shims and a crush spacer, but I don't think the spacer fits over the pinion to the bearing.

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RustyNailJustin

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The shim under the big pinion bearing sets pinion depth. Replace it with the exact same size as came out.
Your pinion does not use a crush sleeve. Its machined as a solid pinion spacer. Use the exact same thickness shims that came out. That sets your pinion bearing preload.
Once you get it back together mix a little gear oil in with your marking compound and put a good resistance on the ring while you turn the pinion. Run it both ways and post pics of the drive and coast sides of the ring gear.
You are not setting up gears here just a bearing job so it will be right or extremely close on the first try if you put the exact same size shims back in.
 

brownbear

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So you think I have a shim under the big pinion bearing? I was thinking it was just the one under the race. In this Zuk build he removes the .014 shim, that is pretty much what I had under my race.


My FSM is for 1984, so it doesn't show any of this older style pinion.

I put my new race in with no shim, as I damaged it, and the FSM did not show it. But I am thinking it's the method on this older style for setting the depth.

As far as the pre-load on the pinion, yes I have them shims for that. Also my kit provided some more if I need to increase, or decrease.

Thanks!
 

RustyNailJustin

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There is no shim under the big pinion bearing.

Putting the shims under the race is much easier than under the pinion bearing. You can just use a brass drift to tap it out vs having to use your clamshell to remove and press to put it back on. The other method is make a setup bearing... Different story.
Its not an older style thing. You have 2 options to gain or loose pinion depth under the race or under the big bearing.

Your going to find out once you pull that bearing. It looks like there might be when the bearing is on cause the pinion is stepped a bit there.
 
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brownbear

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Thanks! @RustyNailJustin

I'll use the same thickness under the race to start. I'm waiting on sourcing my bearing splitter locally to pull the big bearing. I tried to pull the bearing with some angle iron cut out and my press. no luck. need the bearing splitter it's really on there.
 

RustyNailJustin

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If you do very many diffs at all this bearing tool is worth it’s weight in gold.
And no worries.
 

brownbear

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Yes I saw that puller being used. That looks pretty amazing. Hopefully I only have to to do my two diffs, and maybe my spares when I re-gear in the future.
 

tmxmotorsports

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If you do very many diffs at all this bearing tool is worth it’s weight in gold.
And no worries.
I have the same one worrh every penny
 

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