Front Diff Failure (FDF)

[Bounder]

My front diff has locked up and I will be pulling it apart tomorrow, It was preceded by a whine under load while travelling at speed 60-70mph.
Travelling up a gentle motorway hill I had a momentary power loss and hesitation and pulled in, it didn't want to move after that with the two front wheels locking up.
Unfortunately mine being a GL has the more uncommon 4.100 diffs so I may have to try and find a pair of 4.300's from a scrapped 90 rather than just the front 4.100.
Talking to breakers they ask are they R15 or R17 diffs? Can anyone enlighten me as to what the difference is?
I was told it was on a sticker but mine aren't the cleanest TBH.
There is quite high miles on this vehicle 262k .
Is there a front diff removal pictorial anywhere or any tips on removing it
Also is it possible to drive it in 2wd with the front propshaft removed and the diff internals gutted so it doesn't lock up.
It would be very convenient to be able to drive around to try and pick up another diff.
Cheers
H

 

[Chris]

Bad news Bounder. This is the 3rd front diff problem recently. Maybe we are seeing the first of a common 'fault - to be' in Colorados.
Obviously until you pull it, you won't know the nature of the failure. The others seem to have been bearing related with ring and pinion damage being secondary rather than the actual failure itself.

Getting the diff off is really easy. If you have any experience on the spanners you'll be fine. In simple terms you need to drain the oil, pull the half shafts, uncouple the prop and the three diff mounting points. I found that it was best to remove the companion flange in the input shaft as I simply couldn't get it through the gap over the top of the front corss-member. Do that whilst it has wheels on so that you can stop the pinion shaft from tuning when you undo the nut.

Nikimiki posted very recently on their diff woes and there are some pics in there. There should be a white sticker on the diff, yes, saying R something. There was on mine but I can't remember which one it was. Perhaps others in the diff club can tell you.

I don't know anyone who has tried to drive in 2WD. I have done that with the rear diff, but not with the front. In theory you should be able to remove the prop, lock the center diff, remove the ring gear from the carrier and drive in 2wd. If your bearings have collapsed then you'd still need to attend to that unless it was the pinion bearings.

4.1 are harder to come by I'd think - yes. Let's hope that it's just bearings and not tooth damage.

Keep us informed

Chris

 

[Bounder]

Thanks Chris
How do the half shafts pull out?
I have the 35mm hub nuts undone, the 4 bolts that hold the bottom ball joint are undone and the hub is free.
The driveshafts are still in the diff, how do they come out Do I just pull hard on the outer CV?

 

[Chris]

Ooh, no need to do that. Just pull the top bolt out of the upper wishbone and lean the whole turret back. The shafts 'pop' out. Use a pry bar and just split them. You'll need two new snap rings to go back on the end. Don't reuse them.

If you have the bolts out then worth looking at a bit of a clean up and service, but no need to undo that lot unless you want to change the whole CV.

Chris

 

[Bounder]

I know the problem now, having undone the front drain plug there was no oil in the diff, the drain plug also had a load of metal shards stuck to the magnet.
Plus the smell of burnt oil is horrible, the seal looks to have gone on the NS and let all the lube juice out, shizer.
Must try and get these bloomin halfshafts out they are a bugger to get at, I may have to stick the bottom ball joint back on and use the leverage idea.
I did all the transmission fluids last year, and they all looked OK except for the front diff which was very black. Have to keep an eye on the front diff oil levels in future.

 

[Chris]

Damn. Check the front diff breather whilst you are at it. Bugg3r to find, but it is there. The little caps on the end always get blocked. This doesn't help and it pressurizes the seals and you lose oil.

Chris

 

[Bounder]

What actually holds the halfshafts in place The lock ring in a machined groove?
I am kind of worried that I will damage something if I go pulling on the end of the shaft assembly.

 

[Chris]

Yep, that's it. Nope you won't damage anything. The circlips are round wire basically. Have faith brother. They just pop out and snap back in. The clip just stop the shafts from dropping out. They don't take any force really. All the force in the halfshaft / CV is rotational. The whole shaft is really just floating between the diff and the hub. Pry bar and pop out she comes.

Chris

 

[TonyP]

As Chris says there is a circulare wire clip on the end of the shaft:

This is the drivers side:

You just need to give it a firm tap

This then fits into another shaft which goes into the diff (on the left hand side of the below pic):

And this sits inside this shaft tube (sorry don't know the technical term):

I found that it's easier to remove the six bots that hold this in place and then pull the whole lot out from the diff. No clips on this end

HTH

 

[Bounder]

Cheers guys, I am just heading out to do this now, old fridge boxes on the drive and lashing rain.
The worst part is I have a shed but it's full of crap and I can't get the car in

 

[Bounder]

Well I got the Diff out and stripped it to see if anything was salvageable.
The ring gear looked OK but after washing it off in diesel there is a fair bit of tooth damage, the pinion is a lot worse though, the shaft has actually bent inside the diff head.
Dry bearing was the cause.
You can see from the state of the drain plug how much swarf there was floating inside.
I have removed the diff and half shafts and used a cable tie and heavy duty PE sheeting to blank off the back of the hubs.
Is there any reason why I can't drive the vehicle with the diff locked like this?

 

[Chris]

Not getting the images there fella.

C

 

[Ecky Thump]

Chris

Right click on the icon and open in a new tab. Prepare for a shock

 

[Chris]

Never thought of that as they didn't seem to be active text.

HOLY 5H1T

Let that be a lesson to anyone who doesn't think that they need to bother with their front diff on a 90!!!

C

 

[Chas]

Chris

Right click on the icon and open in a new tab. Prepare for a shock

Tried that and I don't get the option to open in a new tab, that option is greyed out.

 

[Chris]

Chas, I get 'View Image' when I right click on them.

C

 

[Bounder]

Sorry about the pics, it doesn't seem to format them very well.
I used BBcode but for whatever reason it doesn't work well for me.
Rightclick and view pictures works for me.
Anyway lesson for today is watch your diff oil levels front and back.
Breather worked fine I blew through it and it was clear.
I guess after 262k miles the N/S driveshaft seal just decided to give up and spewed the oil out.
I had been doing some motorway miles 70 mph and that probably didn't help.
I have a secondhand diff maybe sorted so fingers crossed it will turn out good, I will fit new seals to this one before fitting it.

 

[Chas]

Chas, I get 'View Image' when I right click on them.C

No, I don't get that either.

 

[TonyP]

Very nasty indeed......

 

[Chris]

Chas - is that your right click or our right click? Right hand is the one you scratch your bum with - yes?

Chris