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Rear Diff And Lsd Options


Guest Jay Paul

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Guest Jay Paul

So i beleive mine to be a 83 sierra with open diif and thought why not throw a slip in there

 

anyway managed to find 1 but not sure if it will fit could anyone shine a light for me please its a rear LSD out of a 90 XR4x4 ive attached all i know but tbh its not a lot to go on im afraid

 

many thankspost-13829-0-82182800-1473949916_thumb.jpgpost-13829-0-46245900-1473949923_thumb.jpgpost-13829-0-22234100-1473949930_thumb.jpgpost-13829-0-21593300-1473950001_thumb.jpgpost-13829-0-72624800-1473950008_thumb.jpg

Edited by Nobby
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The diff is 7” with bolt on shafts (the single long bolt across the top identifies it as a 7” diff). Your diff has push in shafts so it’s a 7” casing as well (push in shafts are only found on 7” casings – and also on 6.5” diffs which have a smaller crownwheel fitted in to the 7 casing and also have thinner driveshafts so your diff could be a 6.5”). The stamped tag on the back of either diff will give you the actual ratio and whether it’s an LSD or not.

 

If you turn one output shaft on the diff and the other output shaft turns the same way, it’s an LSD (or it’s been welded up inside which some Sierra diffs are for off road racing). If the other shaft turns the opposite way it’s an open diff.

 

The diff should fit your rear beam but you’ll need to get the driveshafts as well and then decide whether you want to swap to rear discs if you’ve currently got drums. Have a look at this for more info:

 

http://nw.rhocar.org/reardiscs.htm

 

http://nw.rhocar.org/lsd.htm

 

There’s lots of driveshaft and diff combinations and not all work together. I bought a 7.5” LSD cheap and then had a right faf and expense getting the correct shafts for it because it had bigger bolt on joints on it. Ideally you might want to consider buying the diff, driveshafts and brakes as a complete unit and then at least you know that they’re compatible and will fit.

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I had a 3.92 open diff in my hood with push in shafts. 86 EFI 2.0L donor. I may have been lucky but was able to retain the shafts, remove the push-in tripode inner ends and replace them with lobros when I fitted my viscous slipper. So I still run the original drums. Big job changing most of the rear end when you may not need to.

 

Nigel

post-21-0-84337400-1473955891_thumb.jpg

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Guest 2b cruising

Ei was ridiculed on here by someone for stating that the diff size of 7" had the diff bolt at 7".

Apparently it is the dia of the crown wheel.

Led on Sierra lsd have a couple of types. A plate type that does lock out the shafts so the both turn the same way when not under load.

Then the common type is done with hydraulic jell resisting the breakaway from one side to the other. Apparently these do turn the none loaded shafts the same as an open diff but have a slight break away resistance. Then of course you have the money man type as in the quaife diffs.

I have a spare open diff bolt on type from the 4x4 that owns me about £100 if you want that.

Shafts etc are going to be used on forthcoming mods so sorry it's only the diff I have.

If you do intend using the 4 x 4 stuff, beware, the drums are the 10" ones so your backs will outperform the fronts wick is never a good thing. The back plates, shoes and drums are interchangeable though so no real problem. Just don't be tempted to use the 10".

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Blimey, never ever seen a 4X4 axle of a Sierra with drum brakes! Nobby, is it worth it you ask? Oh yes it most definitely is. Driving on the limit is so much easier. When mine starts to break away you can feel it happen and you can also feel the diff working to counteract it. Using the throttle and steering to then go where you want it to is not a reaction to a problem but just part of the process of going round a corner with a huge grin on your face.

Edited by Megadodo
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Guest Jay Paul

Blimey, never ever seen a 4X4 axle of a Sierre with drum brakes! Nobby, is it worth it you ask? Oh yes it most definitely is. Driving on the limit is so much easier. When mine starts to break away you can feel it happen and you can also feel the diff working to counteract it. Using the throttle and steering to then go where you want it to is not a reaction to a problem but just part of the process of going round a corner with a huge grin on your face.

 

of so what do i need and where do i get 1 lol sorry for dumb questions im used to big stuff running 37 inch wheels our brake disks were the size of these wheels on the kit cars :rofl:

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I was lucky and managed to find a complete rear axle via this forum (many thanks Bob, it's very good axle!) for a good price and used the whole thing rather than use my donor axle. I have seen them on ebay as complete units since then so just set up a search for Sierra 4X4 rear axle. My donor rear beam looked the same as if the diff would just swap over but I never actually checked but the swinging arms looked very slightly different with abs sensor holes. The driveshafts were different as well with the lsd ones being bolt on and the donor's being push in. You may get away with jut the diff, drive shaft and swinging arms and be able to swap the brakes around, much easier just to get a complete axle, refurb it off the car and just swap the whole thing over!

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Guest lotusPaul

I now have a quaife ATB of 3.54 ratio in my lotus.it was a 3.99 open English side to start with.

 

Is it worth it, well that's a matter of opinion and choice.

 

Yes you will get better traction, yes it can be more stable under braking. Yes it may get some getting used to.

 

No you will not notice any difference what so ever if you drive like you got Miss Daisy in the seat next to you, or if you don't like to explore the A470 like it's the last road with a curve in it.

 

A lot of the time it can be bragging rights in the local, but to be honest it's seldom noticed in cars like ours. It may increase sellability as opposed to value.

 

Before I get the obvious incoming, I swapped to the ATB because the guys that rebuilt my 2000E box and installed the new diff in my casing had a new one on the shelf at a drop dead price.installation was free as they were rebuilding mine anyway.Right place Right time.

If not I'd still have the open diff. And NO, In case your thinking I can't tell the difference either.

 

Hence why I say it's a personal choice.

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Don't know if you've read the links to the rear disc and lsd install on the nw.rhocar site but as already said the drive shafts are bolt on items (i think they are referred to as 'lobro' shafts) as i understand it the outer CV diameter is bigger than the push fit items and therefore even if you get an lsd with the shafts and rear drive flanges you will have to modify (beat with hammer) the rear swinging arms to give enough clearance for the larger diameter outer cv joints. As already stated may be easier to obtain a complete axel - refurb it and swap the lot across.

Cheers

Andy

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Guest lotusPaul

I have a lsd from a Granada, it has rear disks. Ok it's a 5 stud fitment but I'm just thinking outside the box.

Maybe it's worth getting hold of a complete rear axle from granny land and swaping the hubs to four stud fittment.

Possibly a way to lsd and rear disks.

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