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RicardoJM
10-11-2008, 11:59 AM
I was getting around to dealing with the leak coming from the pinon on my rear diff. I thought it was the pinon seal, but think it is my nut. This one is beat up pretty bad on the inside end :eek: and is very likely the cause of my leak?

http://www.risingsun4x4club.org/uploads/ricardojm/rear_diff/w_bad_pinion_nut.jpg

Is this an easy part to get? Does anyone have one lying around that I could use?

I have the front diff from the FJ60 that donated my front disks. The nut looks like it might be the same size, but it is different in that it has an indentation on it, not a blemish but it looks like it is supposed to be there. Could this nut be put into service on my rear diff?

Uncle Ben
10-11-2008, 12:06 PM
Always....always....always use a new pinion nut after removing the old one! It is possible that the pinion flange could weep a little through the splines and come out through the nut. I always apply a small amount of RTV to the inner splines of pinion yokes and T-case drive flanges. Do not put RTV on the splines as it will push into the inside of the case!
I was getting around to dealing with the leak coming from the pinon on my rear diff. I thought it was the pinon seal, but think it is my nut. This one is beat up pretty bad on the inside end :eek: and is very likely the cause of my leak?

http://www.risingsun4x4club.org/uploads/ricardojm/rear_diff/w_bad_pinion_nut.jpg

Is this an easy part to get? Does anyone have one lying around that I could use?

I have the front diff from the FJ60 that donated my front disks. The nut looks like it might be the same size, but it is different in that it has an indentation on it, not a blemish but it looks like it is supposed to be there. Could this nut be put into service on my rear diff?

nuclearlemon
10-11-2008, 05:15 PM
This one is beat up pretty bad on the inside end

http://www.risingsun4x4club.org/uploads/ricardojm/rear_diff/w_bad_pinion_nut.jpg

?

are you talking about the egde where it's deformed? if so, that's from staking the nut. that's normal. you can get new pinion nuts from the dealer. put a bit of silicone on the ends of the spline, slap in a new seal while you're there, torque it all down and restake. easy to do.:thumb:

RicardoJM
10-11-2008, 07:24 PM
I picked up a new pinion nut at Burt, ran into Tch2fly while I was there. It was nice to run into someone I know.

The old nut had been installed backwards by the PO, not with the beveled side out where it could be staked. I did not realize it was backward installed when I posted this morning.

I put everything back together topped off the rear diff with 90 wt. and took it for a test drive. I think I've done something wrong as I now have a metal-on-metal scraping noise coming out of the rear diff.

Retracing my work;
I disconnected the drive shaft
removed the pinion nut
took off the washer
took off the Universal joint flange
took off the dust deflector
found the pinion nut to be bad
cleaned the parts in the washer
bought a new pinion nut
put the parts back on
filled with 90wt
went for a drive, got around the block

While everything was off, I did notice there is about 1/4" play in the Drive Pinion, which is not a good thing. The FSM indicates the pinion nut should be torqued to 144-173 ft lbs, which is a bunch of torque. I did not use my torque wrench, but got it on there good. Perhaps I over tightened the pinion nut. It is also possible I misaligned splines or the drive shaft. I'll have another look at it in the morning.

Seldom Seen
10-11-2008, 08:56 PM
I Don't know if that diff has a solid spacer or a crush sleeve, with a torque range of ~30ftlbs I'm guessing sleeve, I'm willing to bet you my have FUBAR'd your pinion bearing preload.

Uncle Ben
10-12-2008, 02:14 AM
While everything was off, I did notice there is about 1/4" play in the Drive Pinion, which is not a good thing. The FSM indicates the pinion nut should be torqued to 144-173 ft lbs, which is a bunch of torque. I did not use my torque wrench, but got it on there good. Perhaps I over tightened the pinion nut. It is also possible I misaligned splines or the drive shaft. I'll have another look at it in the morning.
:confused:
1/4" play? You mean after the pinion is torqued down you can still move it in and out 1/4"? It sounds like your crush sleeve was never crushed enough! If thats the case and you have been driving it that way you might have some other issues now! When preloaded properly you should have 0 play and the pinion without ring gear should feel tight but still move by hand. Once torsional pressure works on the assembly a few hundred miles the pinion will turn much easier by hand but still have 0 play! Something is very wrong with your setup and I suggest letting someone who knows how to set up R&P's take a look at it!

60wag
10-12-2008, 07:22 AM
By play do you mean looseness in the pinion bearings or rotational play which would be gear backlash?

RicardoJM
10-12-2008, 09:40 AM
My earlier post was not as clear as it could be regarding the 1/4" play. The play is with the pinion nut, universal joint flange and dust deflector off. Once these parts are all back on, there is no play - everything is solid.

Uncle Ben
10-12-2008, 09:57 AM
My earlier post was not as clear as it could be regarding the 1/4" play. The play is with the pinion nut, universal joint flange and dust deflector off. Once these parts are all back on, there is no play - everything is solid.

Ahhhhhhhhhhh...That is normal as when you remove those parts the pinion can move deeper into the ring gear which unloads the bearing cones. The metal grinding obviously is still an issue. Two things to check is the dust shield on the pinion flange and if you removed the slinger that is on the shaft behind the pinion flange. See if there is any shiny spots which would indicated interference with another part. The dust shield on the pinion flange is very easy to distort.

MDH33
10-12-2008, 10:07 AM
If I recall, the torque value for an FJ40 pinion nut is ~180-300 ft/lbs. You should have replaced the seal while you were in there and checked the flange surface that rides on the seal for wear. Not sure about the grinding.

subzali
10-12-2008, 10:33 AM
Agreed, the leak is most likely the seal, but as UB a little RTV on the flange splines always helps. The nut itself shouldn't be holding back any oil.

Make sure the grinding is not related to something else, sometimes these things like to insert unrelated issues when you're trying to take care of another issue ;)

RicardoJM
10-12-2008, 12:03 PM
I went out and took another look this morning. I removed the drive shaft and confirmed with my nut on there is no side to side or up and down or in and out play, there is a little rotational movement which is ok and feels good.

I checked the dust cover and it did have a slight bend on the lip, but it did not look like something that would be rubbing, but I bent it back out just in case. As I did not remove the seal or any of the other parts and likely did not dislodge anything, I put the drive shaft back on.

I took it for a test drive and the noise was still faintly there. It seems to be gear related as it would change in pitch versus being constant. IIRC the noise started towards the mid range of 1st but would get quite (or be drowned out) by the upper end of 1st. No noise in 2nd or 3rd. I drove for about 5 miles at a mix of neighborhood and boulevard speeds and by the end of the drive there was no noise. I checked the pinion area of the 3rd member and there was not heat.

Unlike the front axle area where I had been in there, seen things and had them explained, I'm a learning as I go with this rear pinion. I am concerned that my noise seems to have gone away - and I can't explain why. Shoot, I don't know if I'm crushed sleeve or spacers and just noticed I couldn't spell pinion correctly in the title of my thread.

Perhaps, it would be best to have an expert go through my 3rd member and refresh/repair items needing attention. What shops/individuals would you recommend?

Rzeppa
10-12-2008, 02:38 PM
A stock 1971 3rd member does not use a crush sleeve - pinion preload is done with shims and is checked with an inch-pound torque wrench. Sometimes you have to take it apart and put it back together several times to get the shim thickness right. When simply replacing the seal, whatever shim(s) were in there should be fine, they really only need to be re-done when you replace the bearings. The nut gets honked down really tight, way over 100 ft-pounds. The scraping sound may have been your dust shield being a little tweaked.