Diff centre colapsable spacer question

[DAZ]

In my 80 the rear pinion was leaking so i un pinched the centre nut to find it is very loose i replaced the pinion seal and have done the nut up tight which has gone 3/4 of a turn past where it was dose that alter the preasure on the bearings or the mesh of the crown wheel and pinion ? there is no noise im sure all is fine in there at the moment what will it end up damageing if it is going to be a prob ? should i have it rebuilt now or just keep an eye on it thanks Darren

I guess im saying what is it that alters as the colapsable spacers start to colaps ?

[dumbdunce]

I guess im saying what is it that alters as the colapsable spacers start to colaps ?

what changes is the preload on the pinion bearings - it does not effect the contact pattern - UNTIL the pinion bearings collapse from excessive preload. It's difficult (almost impossible) to get perfect, working under the truck and without replacing the collapsible spacer. A lot of shops won't even do the job you have just done for fear of messing up the bearing preload.

if you haven't driven it much, jack up the back so you can turn the wheels, drop out the tailshaft, and see how difficult the pinion is to turn by hand. if there is a lot of drag it is done up way too tight, it should be done up to the point where there is zero play and only a very slight 'drag' on the bearings - easy to turn by hand but still with some slight resistance felt. it's very hard to get right with the diff assembled and is supposed to be set up with the carrier and crownwheel removed AFTER the contact pattern has been set.

you can fiddle with it to try and get it close but there is no guarantee how long it will last- you might get 5000km or you might get 50,000. bottom line is you're just putting off an inevitable diff rebuild - 80's are famous for chewing up carrier bearings anyway. a fresh set of bearings plus setup should be around $400 if you R&R the diff.

good luck!

Brian

[DAZ]

Thanks for that i understand what you say ill do as you sujested i thought it did muck with the bearings i have been touching the diff houseing to see how hot it gets but it so far has seemed to be fine from that poit of view


some one else has suggested having it assembleld with a solid spacer insted of collapsable is this found to be successful and dose it make them more likly to take more abuse ? that i expect would be the same with the front hi pinion centre? even if all is in ok condition is this a easy thing to do and should i get it done now ? thanks again for any advise Darren

[dumbdunce]

Thanks for that i understand what you say ill do as you sujested i thought it did muck with the bearings i have been touching the diff houseing to see how hot it gets but it so far has seemed to be fine from that poit of view

some one else has suggested having it assembleld with a solid spacer insted of collapsable is this found to be successful and dose it make them more likly to take more abuse ? that i expect would be the same with the front hi pinion centre? even if all is in ok condition is this a easy thing to do and should i get it done now ? thanks again for any advise Darren

most of the heat generated in the diff comes from shearing of the oil due to the sliding contact of the gear teeth. having the bearings wound up too tight won't generate much extra heat, will just generate excessive strain in the rollers and races and cause them to fail catastrophically - when that happens you have almost no warning, then about 100km before you take out the cw&p as well.

the solid spacer is good for if you ever want to replace the seal without playing with the preload; you can pull the nut and flange off, change the seal and replace the flange and nut, then do up the night as tight as you can and the solid spacer sets the preload rather than the collapsible spacer and specific torque on the nut. you need to pull the diff and get it overhauled to have the solid spacer setup installed. can be done front and rear. so either way you're in the same boat - the solid spacer is a good option if the diff is already out for a rebuild but it doesn't make the diff any stronger.

cheers

Brian

[DAZ]

thank you food for thought i think ill remove it and make sure it is right soon as it is not a big job to pull a rear centre out and im sure it will be cheaper to have it looked at sooner rather than later Daz

[dumbdunce]

...cheaper to have it looked at sooner rather than later Daz

definitely. do it now and it costs you a set of bearings, leave it till it collapses and you could be up for gears too.

you can drive around on the front if you need to in the mean time, too.

[80UTE]

I set up all my lateish Cruiser Diffs (collaspable spacer type) with a solid spacer and shims to set the preload as per the 1984 and earlier diff, i have found this to be the best system as it takes a bit longer to set up but worth it in the long run. If the seal starts to leak its a much simpler task to replace as you dont need to dig the front bearing to get the sleeve out, replace the sleeve and put it back together. Pull the flange off dig the seal out clean up the bore fit the new seal fit the flange and tighten job done. With the solid spacer the pinion flange stays tight as all with the collaspable spacer would know the flange comes loose and wears the splines on the pinion shaft and in the flange.

Wally