[Zook_Fan]

My wt sierra has gone through 2 front diffs and 3 rears in the space of 6 months or around 7500km's. Only one hard offroad trip, mostly highway kilometres. What would be causing this? The first for both were the originals, I then swapped to 3.9 NT diff's from SCSW. These only lasted a few months and then they had gone from perfect to pretty much destroyed, heaps of play in the diff, terrible wining noises. I got the original WT diff rebuilt and then put it back in and within no time it was doing the same.

All wheel bearings have been replaced in the last 10000km's. All uni's have been replaced in the last 5000km. I'm only running 2" suspension, 2" body and 235/75R15's. Would bent housings cause this? Really sick of changing diffs so any help would be great.

[31zook]

bent diff maybe, but thats would be destroying the side gears, not ring and pinions.... the oil in the axle might contain fragments of steel from the last diff, if i was you, i would take the 3.9 center to a diff shop, get them to work out whats wrong, then fix what they recommend, then hose out your axle housing with fuel, then redo your wheel bearings that way you have covered all bases

your not rough, so i doubt it would be a putting together error...

[shep]

look at things that haven't been replaced, my money would be on the housings.

[Zook_Fan]

31zook wrote:

bent diff maybe, but thats would be destroying the side gears, not ring and pinions.... the oil in the axle might contain fragments of steel from the last diff, if i was you, i would take the 3.9 center to a diff shop, get them to work out whats wrong, then fix what they recommend, then hose out your axle housing with fuel, then redo your wheel bearings that way you have covered all bases

your not rough, so i doubt it would be a putting together error...

Yeah every time i change a diff the whole housing was washed with fuel through high pressure spray. There was absolutely no metal left in the housing. The ring and pinion's don't seem to have any excessive wear or anything like that, it just seems to be getting out of spec enough that it is wining and the pinion bearing is failing. I will put up some photo's to see if there is something I am missing.

Yeah shep that is what I was thinking to but just wanted to see if it could be something earlier in the drivetrain causing problems, perhaps a transfer fault or something? Its got me

[billrogers]

How much do you use 4WD? Not permanantly in 4WD?

[31zook]

The tcase couldn't be doing anything, i guess you should just check how your driving style is or the housing.

[lump_a_charcoal]

Are you using mismatched R&Ps?

[Teracis]

Could it be the wrong oil or something?

Or not enough/no oil?

Not saying you'd forget, but sometimes we do silly things you know.

As for shep being on the money though, that's what I'm thinking too, although how could you get the axles in properly, wouldn't everything not fit properly and not want to turn?

[steve]

Haven't been doing jumps have ya ZookFan????

[11_evl]

Using engine oil instead of diff oil does that fast.
Driving style, clutch dumps and compression skids can cause that
Hitting tailshaft on rocks can be a problem. Collaspable spacer crushed

[Built4thrashing]

Zook_Fan wrote:

My wt sierra has gone through 2 front diffs and 3 rears in the space of 6 months or around 7500km's. Only one hard offroad trip, mostly highway kilometres. What would be causing this? The first for both were the originals, I then swapped to 3.9 NT diff's from SCSW. These only lasted a few months and then they had gone from perfect to pretty much destroyed, heaps of play in the diff, terrible wining noises. I got the original WT diff rebuilt and then put it back in and within no time it was doing the same.

All wheel bearings have been replaced in the last 10000km's. All uni's have been replaced in the last 5000km. I'm only running 2" suspension, 2" body and 235/75R15's. Would bent housings cause this? Really sick of changing diffs so any help would be great.

What exactly is letting go inside the diff ctr? is it chewing bearings or snapping teeth or side gears?

[daisy]

Built4thrashing wrote:

What exactly is letting go inside the diff ctr? is it chewing bearings or snapping teeth or side gears?

Very good question there.

chewing bearings or snapping side gears etc - bent housing or axles

snapping teeth - bad install - preload or backlash set wrong.

pinon - driveshaft related or wrong preload

when you rebuilt it... did you reuse the same spacer in the pinon???

as that couldve been the problem to start with as spacers are collapsible.

[Zook_Fan]

billrogers wrote:

How much do you use 4WD? Not permanantly in 4WD?

Nope, front is disengaged as soon as i get on bitumen. Would have been barely time between the last front diff changed.

31zook wrote:

The tcase couldn't be doing anything, i guess you should just check how your driving style is or the housing.

I don't think it is driving style, I am fairly soft on it and i've only got a 1.3 at had so I don't think power could be to blame

lump_a_charcoal wrote:

Are you using mismatched R&Ps?

Nope always matched pairs

Teracis wrote:

Oil stuff

It has always had oil in it. Morey's stabiliser was added once the wining started in both instances.

steve wrote:

Haven't been doing jumps have ya ZookFan????

Yeah it has found air a couple of times. Never intentional or very high, just high speed, low, flat jumps on a rally course.

11_evl wrote:

Using engine oil instead of diff oil does that fast.
Driving style, clutch dumps and compression skids can cause that
Hitting tailshaft on rocks can be a problem. Collaspable spacer crushed

Diff oil used. As above I don't think driving style is the problem, the second and third diff I changed my driving style in an effort to stop it happening again. Could have been rocks...

Built4thrashing wrote:

What exactly is letting go inside the diff ctr? is it chewing bearings or snapping teeth or side gears?

Bearings. Teeth are fine.

daisy wrote:

Very good question there.

chewing bearings or snapping side gears etc - bent housing or axles

snapping teeth - bad install - preload or backlash set wrong.

pinon - driveshaft related or wrong preload

when you rebuilt it... did you reuse the same spacer in the pinon???

as that couldve been the problem to start with as spacers are collapsible.

Side gears are fine, teeth are fine. When you say pinion do you mean teeth or pinion bearing? Pinion bearing was shot the first time but I believe that was uni related. New spacer when rebuilt.


So in summary I am thinking housings and or axles are to blame.

[Built4thrashing]

Housing is bent. replace the housing and your problem will go away.

[daisy]

pull axles and diff centre out...
and pull those seals out as well.. have a look thru it from one end to another..

You can see if the tube is curved looking through it which will give you a better idea of how bad the housing is bent.

[SSSIERA]

havent been playing in puddels have ya ????

[Zook_Fan]

I will be replacing the housing. Definetly bracing the new one before it goes in though.
I have been driving through mud if that is what you mean but that is not the issue as the oil has always been clean when changed.

[TZAR]

Zook_Fan wrote:

I will be replacing the housing. Definetly bracing the new one before it goes in though.
I have been driving through mud if that is what you mean but that is not the issue as the oil has always been clean when changed.

Before you brace the diff weld it to a piece of solid steel that wont twist or bend. Once you weld to the diff and allow it cool it will twist unless braced to stop it.
noob cad