Sierra diffs

[Guest]

Hello all,

Collected my diff (3.62) today from the breakers except I got the whole rear axle, which I was told came from a Sierra 2.0 4x4.

Now, I know the 'check' for a LSD is to turn one wheel and the other turns the same way but....I get the feeling mine might do this simply because it's a bit stiff. Also, one wheel was jammed when I got it and turning the input shaft rotated the free wheel easily, with no noticable limited-slip action!

Does anyone know what type of LSD Ford used? If it is a Torsen(? ) then I believe I _might_ have a LSD since these require both wheels to have a certain amount of traction, which the free one didn't.... (that might be b*****k as well - just quoting stuff I read on howstuffworks.com )

Anyway, back the rear axle thingy: I have being trying to undo the driveshafts (shattering my Torx bit in the process! ) at the inboard end (as recommended by Haynes) and was wondering what parts I need since if I need the free the outboard end I have to somehow get the hub nuts undone. This is gonna be #### near impossible since there is no 'car' to rest on the ground whilst loosening them....any ideas gratefully received

Lastly, can anyone lend me a 18mm x 1.5mm pitch tap? I would have bought it but £17 seemed a bit steep since it's only needed to clean the epoxy from 4 holes! I will gladly pay all postage &/or provide beer tokens (within reason )

Thanks,

- Dan.

[Blatman]

You won't generate any where near enough speed/torque by hand to "test" the lim slip action, so don't try......

Boggo Ford LSD's are a viscous type, IIRC, although I have no idea how they actually work, just that they do, and are actually quite nice to use on a Westfield.

If you have one "wheel" noticeably stiffer than the other, you need to investigste why. If you're up north(ish), speak to SPC, if you're down south, Road and Race Transmissions are the boys to ask, assuming you aren't a vehicle technician/engineer/diff designer/experienced in diff rebuilds..........

[Westfieldman]

You need the diff unit, the brake callipers and the mounting brackets and the outer drive shafts.

To remove the torx bolts gring the heads off with a cutting disk then undo from diff with grips bin lobo joint use new ones.

To undo the nuts on the outer drive shafte carefully grind away one flat of the nut and then with a 41mm socket and a pair of stilstons on the drive shaft you should get the nut off only grind down untill just before the thread shows through the nut will then split and come off ease ish.

car'nt help on the tap job but try a Ford dealer

Paul.

[Guest]

Cheers guys,

bin lobo joint use new ones

I assume this means I have to buy four (from Westfield?) at £40something each? A**e!!

FYI, viscous diffs work by having a paddle in that rotates in

a thick (viscous ) fluid. As the paddle spins faster (i.e. when one wheel is spinning) the amount of drag on the paddle increases, hence increasing the torque to the other wheel.

(Probably a simplified explanation but the basic theory's there....)

[JonnyBoy]

regarding the tap, i went into my local garage and asked nicely. easy peasy  gave the bloke a couple of quid for a beer and we were all happy.

btw, i messed around trying to find cheaper suppliers of bits for my car after someone else advised me to do so. turns out westfield are quite competetive for most things..you do have to pay p&p though

[eusdean]

Changing the thread slightly but still related to LSD Diffs - What oil should I use in a standard ford 4x4 diff ??????

Have spoken to local Ford garages and have had quite different verdicts. One said I had to use an LSD oil while another said their technical books make no distinction between LSD and non LSD diffs. They should both use the standard ep90 grade transmission fluid.

Can somebody help with this as I have emptied all the oil out with a view to renewing it prior to fitting the diff to my car.

     

TIA

[Blatman]

Yup. Bog standard EP80-90 or EP90. The spec to look for on the bottle is GL4.........

[Westfieldman]

Local motor factors do lobo joints at a fair price the boots on the old ones could be split or about to the diff drive shafts should be a fit and almost forget job as its not that easy to do with every thing in/on the car easier job now than later.

Paul.

[Bananaman]

I think you will find that the Diff you have is a 3.92 Viscous LSD (thats if the car was post 90ish) this will make your car accelerate quicker  with a lower top end . These cars are all about acceleration and handelling topend isn't really an issue in my book, unless you want to do a lot of touring around & then you don't need an LSD anyway.

These units are like rocking horse **** i.e. hard to get hold of so looks like you have done well

I've just spent 2 weeks tracking one down.

Good luck (sounds like you have allready had some)

Andy

[Buzzer]

I wouldn't expect the diff to be a 3.9, a 3.6 (ish) is much more likely. I got mine of a 91 sierra 4.4 and it was if I remember a 3.6 (or less) I rebuilt it and changed the crown and pinnion with a 3.9. On the oil front the LSD action is as the thread says via a viscous coupling. This unit is sealled inside the diff, no diff oil circulates in the viscous coulping. I think in fact it uses special silicone fluid. So as Blatmann says good ordinary diff oils will do. And on removing the torx bolts. Invest in a professional grade torx socket, 3/8 drive and use a solid 3/8 drive tommy bar (not ratchet). Maybe some gentle Universal fixing tool application  (hammer). some heat or WD may help. if not the a sharp wack with a chisle should do it. I found that you don't need to grind off the heads. good luck with it all

[Westfieldman]

But its a lot quicker and less painfull to grind them of than damage torxs bits and nuckles etc.

[Matt Seabrook]

If the diff is from a 2000cc 4x4 the it is very likely to be a 3.92 diff and not a 3.62. The 3.62 diff was fitted to the 2.8 and 2.9 Sierras

[Guest]

I can confirm the tag on the diff has 3 62 on it so I'm assuming this means 3.62..... This is probably better for me anyway since this is gonna become my everyday car

Tried using loadsa WD on the Torx bolts today with no effect. Also tried anti-seize stuff which still hadn't worked (even after a few hours).

What kind of heat source is suitable for freeing bolts? Obviously I'm gonna need to direct it fairly precisely and into a pretty small area - 2 requirements that are kinda contradictory...  

I've got a small (pen-sized) blow torch which is directable(?! ) but probably not powerful enough. On the other hand, I've also got a bl**** great blow torch that'll likely incerate the entire diff!

(I'd rather not do any grinding since I've not wielded an angle grinder before and don't really want to practice on my nice diff)

[Westfieldman]

You only gind cut hrough the bolt heads and then slide the lobo joint off the studs that are left sticking out of the diff flange then turn out with grips.

Paul.

[james grayley]

ive dismantled a couple of these back ends and to be honest u shouldnt need any heat. as previously stated buy a *good* torx bit from local factors or even halfords professional are up to the job. these will definately not break or damage the splines etc. get a good 3/8 drive bar and u should be able to free the torx bits no bother. the longer the bar the better cos if u get a good torx bit u wont ******* it with a long bar.

with regards to the drive shaft nuts these again should be removable with a socket and bar if you can get the hub into a large vice. remember one has a reverse thread.

invest in the right tools... will save u alot of p******** about and should be stripped in an hour.....  

hope this helps.