Sierra LSD question

[ginge]

Hi guys, I was wondering if anyone would be able to help me out with a query with a Sierra limited slip diff.

I am currently trying to strip one down to clean up and use in a kit car and am stuck trying to get the mechanicals out of the casing. I have taken out the two splined shafts that go to the drive shaft mounts but am unsure as to how the two parts with teeth on the outside are removed. Are they tapered so that they just fit on or are they threaded? A combination of both perhaps? If they are treaded does this mean that Ford have a special tool with 20 odd teeth to undo this part? Any advice gratefully received! If anyone has a link to a guide on how to do this that would be even better.

Many thanks in advance,

ginge

[dern]

Sorry, can't help but where did you find one?

My local scrappy has a xr4x4 in but it's buried under other cars and behind some more cars so they can't get the crane to it... argh!

Mark

[ferg]

Those multi-toothed bits are screwed in and anchored using a little plate held on with a torx bolt IIRC.
I believe they are set to pre-load the diff.

[theconrodkid]

you talking adout the 3" or so dia rings?they set the preload,shouldnt be moved unless you have the gear and knowledge to re-set the diff

[ginge]

Cheers for that ferg, will have to make some cunning contraption to get it off then.

Got it from a scrappie in Loughborough dern. Am up at uni here and a guy wanted one for his Robin Hood. Have exactly the same thing back home so I get to practice rebuilding his before I play with mine Nice 944 btw.

[ginge]

Is there a special Ford tool for undoing and setting these back up then? I'm afraid I don't have the knowledge to recalibrate them but I can talk to the technicians in the automotive engineering and see if they can help with the set up. If there is a special tool do you have any idea what the part number for it is?

Thanks again!

ginge

[rat7]

Does anyone know if diff ratios are changeable between sierra diffs. So that an LSD can be built up with the ring gear and pinion from an open diff of different ratio to give the same overall gearing and speedo accuracy with an lsd in the system?

[ginge]

rat7 said:

Does anyone know if diff ratios are changeable between sierra diffs. So that an LSD can be built up with the ring gear and pinion from an open diff of different ratio to give the same overall gearing and speedo accuracy with an lsd in the system?

Good question! I'd like to know that too!

[stylusboy]

I may have a few answers from my own experiences (experiments would be more accurate).

1) Yes, it is possible to remove the castellated and threaded bearing carriers, mine were very tight and I had to make up a tool to engage the castellated aluminium sections. This needed a 3-foot long handle! The special tool did the trick but took a day to make, it does need to reasonably well make or you will break the aluminium.
2) These castellated things do set the preload on the bearings and the backlash between the crown wheel and pinion. I measured the backlash on the crown wheel before I took the diff apart. As for the pre load, well I just tried to get a feel for the resistance to movement. Not much on a used diff.
3) In my case I wanted 3.92 LSD. So I got a 3.92 diff off a bog standard Sierra, stripped the internals out but left the pinion untouched. I did the same for my LSD from a 4X4 Sierra. I then transferred the 3,92 ring gear on to LSD assembly and put the whole lot into the 3.92 casing using the 4X4 diff bearing carriers. I set the backlash as it was on the 3.92 diff and judged the preload by hand. I can only say that so far it seems OK! I have no idea if this is recognised practise so try it out at your own risk.

Hope this helps.

[rat7]

Thanks for that stylusboy. May well try to use a new ratio on the lsd for my 2B.

Has anyone out there done similar and then been able to use an electic speedo connected to some sierra dials. Not sure if this is possible without homemade mods of some sort but would be interested in doing so.

[eliot]

Not sure if this applies, as the only diff i have ever rebuilt is a range rover diff.

But there were two nuts either end that effectivley moved the entire assly further or nearer to the pinion gear, thereby setting the backlash. You simply put a clock guage on the carrier and ensured you had a few thou all the way round

[Liszt]

Have also done the internals swap.

Got a 3.62 LSD and a 3.36 open diff. Used a cold chisel and a pry bar between the castellations. While mate hit chisel to turn the part, I lent on pry bar to provide a turning force. Got them off eventually and replaced them as we were doing the bearings as well.
Did not remove pinion gear from the 3.36 as apparrantly that is the bit which is difficult to set up. Mate set up the rest of it as he has rebuilt loads of diffs before.

[cmsapms]

I also have swapped ratios, putting the LSD gubbins from my 3.62 unit into a 3.92 unit.

I got the castellated rings out by using a long square section bar that fitted snugly between the castellations, tapping the ring to break stiction while leaning on the bar.

Before dismantling anything, I measured the backlash on both units with a cheap DTI (dial gauge), and the preload using string and a spring balance (a quid from local shop (for local people)).

I used these measurements to rebuild the LSD enabled 3.92 crown wheel back into its original casing.

Cheers

Paul

[rat7]

Some good info there guys. Always good to pick up several methods and to know someone else out there has done similar.