diagnosing and addressing rear pinion slack

[stayalert]

So it seems my new to me truck has some slack at the rear pinion. It wasn't evident while I was going over the rig on the ground or while driving the 2,200 miles home, but now having put it in the air I can get a slight wiggle of the flange forward of the rear diff that the rear u-joint bolts to. I was hoping to convince myself it was slack in the u-joint.....no dice....

Gulp - The truck is an '87 JDM BJ74 with cable lockers. Am I correct in thinking that this makes it extra challenging to find a suitable replacement 3rd member?

What are my best methods/options of 1) detailing the extent of the problem and 2) correcting the problem.

I have alloted time and $ to get this truck baselined and ready to work. I have some tools and have accomplished things like broken birf replacements, complete front axle services at my house but have yet to crack into a diff.....

Eagerly awaiting wise cracks and other useful and useless opinions and information....

Kind regards.

Rob "slacker" M

 

[stayalert]

I am rapidly approaching the realization that I do not have sufficient 's to apart (not to mention back together!) a diff.....Currently thinking of finding a local shop or shipping 3rd to someone for rehab....Anyone???? Bueller???

 

[inkpot]

It is normal to have a certain amount of rotational movement. That is the space between the teeth of the gearsets. On the other hand, it is not normal to have lateral movement or in/out movement. That can be from must a loose pinion nut, or it can be from pinion bearing wear. John

 

[crushers]

okay,
does it move up and down at all?
does it rotate more than 1/2" left to right?
IF it moves up and down, then the pinion bearing is on its way out.
if it rotates more than a 1/2" then the back lash needs setting up.
IF it is a semi floater and stock ratio then the rear can be swapped for a 40 front or rear, 60 front or rear, 70 front (pre 1990) or rear or 80 series rear center unit with 4.11 gearing.
if not then take it to a reputable shop and get it worked on.
cheaper if you remove the center unit.

 

[stayalert]

Not so much rotational as up & down. I am going to drop the rear shaft and see if the pinion nut is loose. Not counting on that as a solution though.....Any tips on pulling the third member for this cable locked full floater? seems like I lock the diff, pull the halfshafts out of the diff and remove the diff.

I'm kind of sad I included my 80 series manual with the sale of my 80 series.....

 

[crushers]

in a nutshell,
yes

 

[stayalert]

5-18-2012

Update - I drained the diff and screened the oil through a fine mesh....The magnetic drain plug had no ferrous metal on it and the oil had nothing that the fine mesh could pick up. The oil looked uniform and pretty much like gear oil....

I dropped the rear drive shaft and with the wheels still on but in the air there is 1/8" - 1/4" rotation play in either direction. there is a perceptible ~1mm up and down/side to side movement when you grab onto the flange and try to rock it....

in and out movement of the flange is very small/barely perceivable (<1/4mm?)

The pinion nut is loose. it is staked to the groove/keyway on the pinion but it is less than finger tight.

I am of the mind to unstake the pinion nut, firm it up, restake it and drive it. I would monitor it frequently for noise/play....There is no evidence of any leakage from the pinion seal.

comments?

 

[OGBeno]

Hey! You never called back.

 

[stayalert]

Hey! You never called back.

Fark! Sorry man. I will, you can count on it...I'm thinking Monday....Have a great weekend!! wrench:banana:

 

[BeratE]

Not sure if it is like my tacoma diff, but from the factory the pinion spacer is a crush sleeve and they seem to compact or crush more over time. When I redid my diff I used a solid spacer this time so it won't happen again

 

[stayalert]

Not sure if it is like my tacoma diff, but from the factory the pinion spacer is a crush sleeve and they seem to compact or crush more over time. When I redid my diff I used a solid spacer this time so it won't happen again

yeah factory is crush sleeve....I have little reason to believe the diff's ever been opened up before (still has stock gears...) rig has 212,000Km's & the last few years has had an OME lift.....

 

[pradocruzer]

"I am of the mind to unstake the pinion nut, firm it up, restake it and drive it. I would monitor it frequently for noise/play....There is no evidence of any leakage from the pinion seal."

That is what I would do and have done on many vehicles.
Tighten it till there is no slack then tighten a bit more.
If you over tighten it it will preload the pinion bearings too much
causing rapid destruction and noise. If you leave it it will cause rapid destruction and noise. Your really at no loss. The proper repair is to throw a bearing kit in it and have some one set it up.
My method is set an air gun on the lowest setting to take up the slack then set it on the highest setting and give it two or three buprs with the air gun stake it and your done. To crush a new crush sleeve with an impact takes a very good impact gun, serious air source and some blood and sweat. (by the way this is not the preferred method when setting up pinion preload with a new crush sleeve). A flex bar and 3 ft pipe will crush the crush sleeve and not damage the bearings where as a air gun can cause small impacts in the race. Tighten it and see.

Take Care