Pinion pre-load advice (1 Viewer)

[jgranthevagrant]

Truck is a 1990 w. 22re. Should be 4:10 gears and the 7.5 rear diff.
I noticed diff fluid leaking from the pinion and the housing area, so I decided to re-do the carrier seal with FIPG and get a new oil seal for the pinion. I had a new seal already in when I started pulling pieces of rubber off the pinion. So I decided to wreck the new seal and check a bit further. Pulled it apart down to the front bearing, which looks fine. Ordered new bearing spacer and another seal. FSM says to set pinion pre-load with an old-school looking inch pound torque meter, which I don't have. I have a torque wrench that you set and it clicks. Is there a way to set the pre-load properly without that little torque device? Well enough that I don't blow the diff far out in the bush? I want it to last about another 20000 k while I look for axle upgrades. I did a search on here and read some of the ZUK threads. Any tricks beyond the FSM would be useful.

 

[KLF]

Once you've done a few dozen diffs you can do it by feel. But if you've never done one, you need a beam style or meter style torque wrench, and it is very low range. A click style torque wrench won't work, plus keep in mind that torque wrenches are very inaccurate at the bottom end of their scale. Best wrench for doing this is a Park Tools TW-1, I have one and it's perfect for doing this.

Other tips:
Put a thin schmear of RTV on the very outer edge of the seal before installing into the housing. Also put RTV on the pinion splines, so gear oil can't leak through them.
Red locktite on the pinion nut, don't reuse the old one.
You will need a very large wrench to crush the sleeve, and a way to safely hold the diff.

 

[Prairie Swamp]

KLF's advice is all good. Here is a beam style in-lb torque wrench that I have (or very similar) for $25:

https://www.amazon.com/Performance-...-3-fkmr3&keywords=bicycle+torque+wrench+in-lb

You're saving so much money doing the job yourself that you're totally justified buying a tool or two that you'll have for the rest of your life. That's the way I look at it anyway.

You will have to have a way to adapt up from 1/4" drive to the pinion nut as well (no prob at all if you have a welder.)

 

[jgranthevagrant]

Thanks KLF and Prairie Swamp. I want the diff to last long enough before I find a hub to hub with e-locker, so I need to get this right. I can buy a 4th!! torque wrench tomorrow for $70 can, which will be faster than amazon. I'm used to buying tools like engine hoists for bigger jobs, so this won't be that bad. Just trying to dodge buying a tool that I won't use that much. I mangled the stake nut getting it off, so no danger of using again. There is no crush sleeve, as far as I can tell. It is a bearing spacer, and the brand new one looks the same as the old one. Not sure why Toyota says to not re-use it. I should be able to use socket adapters to go from 1/4 drive to the 30mm pinion nut. KLF, do you mean put RTV on the black part of the seal that goes against the pinion or the metal part of the seal that seats it?

 

[jgranthevagrant]

Update. Looks like Park Tool TW - 1 was discontinued in 2016. Also, the FSM is unclear on exactly how the pre-load backlash is measured. Point at which the pinion begins to turn the ring gear? Contacts the ring gear?

 

[Prairie Swamp]

Update. Looks like Park Tool TW - 1 was discontinued in 2016. Also, the FSM is unclear on exactly how the pre-load backlash is measured. Point at which the pinion begins to turn the ring gear? Contacts the ring gear?

Dial indicator on the flat face of the ring gear tooth. Hold the pinion fixed and move the ring gear back and forth until it "clicks" as it contacts the pinion teeth. There should be no motion of the pinion - you're only measuring the air gap between the two.

Good on ya for doing the job right.

 

[KLF]

"Pre-load" and "backlash" are 2 very different things.

Backlash is the tiny bit of movement that the ring gear can travel when you move it back and forth, making sure the pinion doesn't move, as @Prairie Swamp described. You need a dial indicator in a magnet base to measure this. The FSM will have the range of allowable backlash.

Pre-load is how tight the pinion bearings are, after the nut is torqued. It's much easier to measure without the ring gear carrier installed, just the pinion in the housing. There are actually 2 pre-loads: starting, and running. Starting pre-load is how much torque it takes to get the pinion to start turning. Running is how much it takes to keep it spinning and is less than starting. This is what you measure with the torque tool.

There are lots of Park TW-1 wrenches on eBay for cheap. Or there is the other one posted above.

Is this a 2WD truck? Otherwise this is an 8" ring gear. And it should be a crush sleeve between the bearings on the pinion. Image I found on the Googles, solid space with shims on the left, crush sleeve on the right.

Since you're not replacing the bearings or gears, you don't need to worry about pinion depth, just put it back together and torque it down (hope you have a big torque wrench).

 

[ntsqd]

I built a tool to measure this. Bolts to the pinion flange and exactly 12" from the center of the pinion there is a loop for a spring scale. Have to hold the scale to always be perpendicular to that 12" distance, but with a little practice it isn't that hard to do.

You really want to check pinion pre-load without the ring gear & diff installed. I realize that isn't always possible, but it is the best way to make this measurement.

 

[jgranthevagrant]

Thanks people. Bought the latest torque wrench today. With some socket adapters. I'm sure it will go okay. I will look at the bearing spacer again. Not sure that it is crushable.

 

[jgranthevagrant]

RE-installed bearing and bearing spacer. Comparing new spacer with 27 year old one there is about 2mm of difference in length and a slight bulge in the old one, but I'm still not sure it crushes. At least not like the above photo. Losing time right now trying to make a seal driver.

 

[KLF]

Post pictures, but that sure sounds like a crush sleeve to me (assuming the old one is the shorter one). That photo above is from a Honda BTW.

A solid spacer is much stiffer, it is machined. It is generally slightly too short to set proper preload on the bearings, you add those very thin shims to decrease preload.

 

[jgranthevagrant]

Yes, the shorter one is the old one. Both old and new are definitely not machined. I will post a picture of it and my home-made seal driver. Not working on it today. Pouring rain.

 

[ntsqd]

One of the OEM solid spacers that I've had was a nicely made casting.

the crush sleaves take a ton of torque to get started, but once started they crush too easily for my taste. I had one in a Ford 8" relax and cause a bit of trouble. I go with solid spacers on Ford 9" and Toyota and Ford 8" diffs.

 

[KLF]

I have a spare TRD E-locker in my garage right now, all torn apart waiting for me to decide what to do with it. The front pinion bearing was trashed when I got it, I believe because the crush sleeve compressed a little.

 

[jgranthevagrant]

Installed second new seal tonight. Put RTV on pinion spline and outside of seal. Re-installed companion flange and torqued the new nut to about 140 foot pounds. does not feel like sleeve is crushing. there is quite a bit of play ( i.e. not drivable) in the pinion. I notice the FSM says to go up to 253 foot pounds, but I'm not sure how I will get to that. Breaker bar and a pipe? Impact? I assume the play in the pinion should be similar to the transmission output and/or the front diff? Any advice is welcome. KLF, what is the e-locker out of? Tacoma TRD 1998 - 2004? There is an e-locker rear end for sale here. From a Pre-runner.

 

[KLF]

You need a lot more than 140 ft-lbs to crush the sleeve, I think you'll be surprised how much it takes to get it started. I have a 4' long piece of 2”x2" angle iron with holes in it to match 2 adjacent holes in the flange. I bolt the flange to this, then clamp it to my workbench with big strong clamps. Breaker bar with cheater pipe on the nut, hold on tight and give it hell. You'll know when it starts to crush, then you slowly turn it in, unbolt and check preload. If you go too far, you get to take it back apart and get a new sleeve, start over.

There should be NO play in the pinion bearings, none.

I don't know if the spare e-locker I have came out of a Tacoma or a 4Runner, they're all the same. It has 4.11 gears, but needs new pinion bearings. The carrier bearings are fine.

 

[jgranthevagrant]

That's what I thought. I will try with the bar and pipe later this week. I'll rent or buy another torque wrench. Mine only goes to 150 ft pounds. Getting quite the torque wrench collection.

 

[KLF]

I honestly never measure the torque on the nut (unless I'm doing a solid spacer), just crank it down until the preload is right. You will spend a lot of money on a wrench that will go that high.

 

[ntsqd]

The first 7 diffs I ever set up used a solid spacer with no shims. They were all long and we had to surface grind them a 1/10,000 or two at a time until we got the pre-load number we were looking for.

I'd bail on the crush sleave entirely and order a solid spacer kit from Marlin. With shims it is a whole lot easier to set up the pre-load.

 

[jgranthevagrant]

Too far down the crushing it road. If I can't crush it, I will change tactics. I now have 5 torque wrenches. I'm already crushing' it. Won't be back at it until Thursday or the weekend. Re-designing my flange holder.