80 series front diff rebuild questions

[Gav missin]

Just wondering if anyone has had the front diff re built on their 80. My auto off road truck is starting to clank excessively on the front when going from drive to reverse and visa versa. Roughly an inch of play in the diff flange. CVS are new so no play that end.Was thinking of just chucking in a good used unit but wondered what the rough cost of a rebuild would be, compared to a used one. Any info or input greatly recieved.

 

[Shayne]

Depends what damage you find inside I guess . I've only watched videos but what puts me off is the fancy yet simple tools they use to set it up and my assumption those tools cost daft money ?

A quick google suggests about £700 if you buy crown wheel and pinion separate from gasket and bearings but then its completely brand new .

I'd expect a diff is childs play to any gearbox specialist and less than an hours work on the bench if you knew an honest one .

 

[Shayne]

Differential Setup Tool Kit (DIFF-SETUP-KIT)

Differential Setup Tool Kit This tool kit includes some of our most popular differential setup tools at a greatly reduced price. These tools make differential work much easier and makes your setup

completeoffroad.com

 

[Jon Wildsmith]

Did you put new drive flanges on with the new CV's? They can have a bit of play in them when they get worn.

The diff probably has lots of backlash from wear in the bearings, which is normal and the bearings may have plenty of life left in them if adjusted back to spec. Trouble is if you adjust it back to spec, you may end up with a noisy diff because the contact moved and isn't so clean. That happened to me a few times when I used to rebuild them for other people. The front locking diffs are the easiest to adjust preload on the carrier because it has those threaded adjusters rather than shims, but setting pinion depth can be very tedious to get right on worn gears. It's worth a go, but it may whine afterwards.

 

[Gav missin]

Thanks Jon. It does whine and whistle a fair bit to be honest already.Think its worth looking at before binning it. I can live with a bit of diff whine but hate the loud clank every time I drop it into gear.

 

[AndycruiserguyLomas]

Like Jon said, it's worth looking at the drive flanges, I've seen them absolutely rounded off as I think they are softer than the driveshaft.
I put new ones on when I rebuilt the front axle on MUD mk2 along with Toyota CV's and inner axle shafts, it's a long term thing.

As Jon also said about setting it up when it's worn, Chris had a go at rebuilding front diffs for folks firstly re setting worn ones up with little success ( still noisy) and came to the conclusion new ring and pinion was the only answer.

 

[frank rabbets]

Sawdust used to cure noisy ones back in 50's but then you had to sell the car a bit quick.

 

[Shayne]

Question for someone who knows more than me , because Gav seems happy to wing it could the clunk be caused by a collapsed crush tube and might replacing that with a solid spacer delay the inevitable indefinitely ?

 

[Jon Wildsmith]

The crush tube can collapse in high torque situations, but worn bearings is the more likely culprit. Setting up a solid spacer can be a lot of work and would need the diff disassembled to get it right. Generally, working on diffs is not complicated, just very repetitive when searching for the best possible setup, especially on old gears which are almost impossible to get a reliable pattern reading from. Best bet would be new bearings, original pinion depth shim, and carrier backlash / preload set to factory spec. New bearings seem to be made with high enough precision that the factory pinion depth shim is the correct one for that casing and gear combination. Change the gears and you start with the factory shim for reference and adjust from there to get a good contact pattern.