Pinion nut is loose - questions (1 Viewer)

[Yellow Jacket]

76 fj40 -front diff has a Toyota eLocker from a fzj80

So I searched and I'm not seeing these answers and appreciate any help. Hope I'm using the right names here as I'm still a newb at this.

The pinion nut is loose on my front diff. It goes from side to side and up down or any other direction you choose by a couple of mm. I know that is a bad thing. I pulled off the driveshaft hoping the nut had just worked its way loose and would be an easy fix. When I first saw it I was sure that was it because it doesn't look like the nut was staked well (or it backed off somehow). See pic below. However the nut feels pretty durn tight.

BUT when I tried to measure preload I got a big zero. FIRST QUESTION: should hubs be locked or unlocked when measuring preload? I had mine locked when I got the zero reading.

With hubs still locked I tried to torque nut down but need to fab the flange tool first to do it right. So that will be tomorrow. What little i could tell it feels tight already. SECOND QUESTION: keep hub locked when torquing nut to spec?

THIRD QUESTION: If it is truly at spec already, then is my only option to jump into the deep end and pull the diff to start tearing it apart and measuring? I've got a bad feeling this is the road I'm headed down.

Thanks.

 

[LAMBCRUSHER]

IIRC, the 80 pinions use a crush sleeve; once it is crushed, tightening the nut will work for a while, but the damage has most likely been done. best course IMO is a solid spacer and shims during reassembly.

 

[john657]

I concur with Lambcrusher. Once the original crush setting is set with the crush sleeve when the diff is set-up and it then loosens up for some reason, you can buy some time by retightening the pinion nut. Eventually, it won't be effective anymore and it needs to be re-set with a new crush sleeve or better yet, a solid spacer and shim. I switched over to a solid spacer and shims in my 1985 Toyota mini Rockcrawler for long lasting durability.

 

[shawnfj40]

I would start by draining that diff and getting a good look at what if anything is in it. Then if I didn't see lots of metal particles I would remove the nut and seal to get a good look at the outer bearing/race. if they look ok replace the crush sleave with a new one and set your preload.

 

[Yellow Jacket]

Thanks for input guys. Didn't known about the crush sleeve. @shawnfj40 I changed the fluids in the front diff months ago. I didn't look extremely closely but I didn't see any obvious metal particles.

Should I have the hubs locked when I tighten the pinion nut? If it can be tightened.

Are Marlin seals considered the best?

 

[shawnfj40]

Marlin seals are the best. The hubs should not be locked. I usually set the preload with the third member out and mounted in my jig. you could use the method that has you use spacers and shims. I have done many that way and it is a permanent fix however having said that, it is a real b!@#tch sometimes to get it right and you need a large variety of shims. They are putting crush sleaves in at the factory now and I have finally come to believe they are fine. When you are setting the pinion preload I am pretty sure they do not even want the carrier installed. You can just loosen and back it off to remove from the equation.

 

[Yellow Jacket]

Well I tightened the nut and could tell some of the slop is gone but not all. I buttoned it all back up so I can drive it (in 2wd) while I start researching this unexpected little joy. Ay threads to start on for an fzj80 diff rebuild? Thanks

 

[Stumpalama]

If it is just replacing the crush sleeve and resetting the pinion preload, a competent shop can do that for less than a couple hundred bucks. There is no need to check gear tooth mesh because you are not replacing the bearings and thus not changing any of the original measurements.
If you are up for it and meticulous, you could do it yourself, just remove the pinion flange, seal and shims (make sure to keep them together and reinstall in the same order), mark the side bearing retainers and threaded collars, count the number of turns to remove each side, pull the ring gear, pull the pinion, install new crush sleeve, reinstall pinion, ring gear, then reassemble side bearing retainers and rethread sleeves to original count on both sides, lock in place. Then double check backlash and adjust to spec. Lastly, replace outer pinion bearing, shims, seal and flange and retighten to proper spec.

 

[Pin_Head]

The front diff on a part time 4WD is a forgiving application. After verifying that the bearing is OK, you could easily get away with tightening it until there is no more lateral slop and then a few degrees more until you get about 6 more inch pounds on the dial and then re-stake the nut. It will probably last forever on the front.

 

[Yellow Jacket]

Thanks guys. So I admit I like @Pin_Head idea, since I don't have to pull the diff out. I think @shawnfj40 was saying the same thing. I need to do some research on how to verify the bearing is OK. Appreciate any links to educate me. I keep finding dead links in the FAQ, but maybe I'm looking in the wrong place or something.

@Stumpalama Thanks for the steps. I admit it sounds a bit intimidating for a one guy like me.

 

[Pin_Head]

I need to do some research on how to verify the bearing is OK. Appreciate any links to educate me. I keep finding dead links in the FAQ, but maybe I'm looking in the wrong place or something.

You are in luck. It is a 1 banana job.
Remove pinion flange.
Remove seal.
Remove outer bearing, clean.
Look at the bearing and race to see if there is any wear or spalling.
If not, replace bearing, install new seal and tighten just enough to gain 6 inch pounds of preload at the pinion.
Stake pinion nut.

 

[Yellow Jacket]

I think I can handle that! Will order the marlin seal tonight. FSM shows a dust cover and an oil slinger. No need to replace those? I'm guessing the rear bearing doesn't get packed with grease since it is sitting in gear oil, right?

 

[Pin_Head]

What comes out must go back in with the same orientation. Put a little grease on the spring inside the seal lip to keep the spring from popping out when you are installing the seal.

 

[Yellow Jacket]

Sure. I meant replace with new or reuse old piece. Thanks for your help and tips.

 

[Stumpalama]

put some black RTV on the flange splines when installing to seal them too.

 

[Pin_Head]

You can normally reuse everything but the seal.

 

[just differentials]

For future reference here is our install guide, with color photos and some pretty detailed info:

http://www.nitro-gear.com/installation-guides/

Also, for anyone else, here are some parts to help you overhaul FJ40 axles:

-Nitro Gear, Toyota Land Cruiser 9.5" Ring & Pinions http://www.justdifferentials.com/SearchResults.asp?Search=tlc-&Submit=
-Master install Kit, Toyota land cruiser 9.5" http://www.justdifferentials.com/SearchResults.asp?Search=mktlc-&Submit=
-Solid Pinion Preload spacers http://www.justdifferentials.com/SearchResults.asp?Search=skcstlc&Submit=
-Ring Gear Nut & Through Bolt kit http://www.justdifferentials.com/IKTLC-RGBOLT-p/iktlc-rgbolt.htm (required for older models that originally had threaded ring gear)
-Nitro Xtreme Rear diff Cover: http://www.justdifferentials.com/NPCOVER-TLC-p/npcover-tlc.htm
-Chromoly Birfield kit http://www.justdifferentials.com/AXTBIRF-FJ40KIT-p/axtbirf-fj40kit.htm
-Knuckle overhaul kit http://www.justdifferentials.com/KNCLKIT-TOY-p/knclkit-toy.htm
-Front wheel bearings http://www.justdifferentials.com/AKTOY-FRONT-p/aktoy-front.htm
-Rear wheel bearings http://www.justdifferentials.com/AKTLC-p/aktlc.htm