Viscous diff

[bryan413]

So I have the opportunity to buy a viscous diff off an ix. I want an lsd for snow only. I dont race my car. But I know how much better an lsd is in the snow. Will this case work on our cars?

[Xenocide]

no

[bryan413]

How come? Its a medium case? It bolts up to any E30.

[pdxmotorhead]

I thought the viscous unit on the BMW had an electrical feed from the traction computer to tell it how much and when to lock up?

Dave

[bryan413]

I thought the viscous unit on the BMW had an electrical feed from the traction computer to tell it how much and when to lock up?

Dave

VLSD dont work in 1980's dont work that way. I dont think they even work that way now.

[pdxmotorhead]

I went and dug around in my magazine stack, it was a center diff for an AWD rig that they were playing with, when you ran an electric current through the fluid it seized and caused the two plates to turn together... Thought BMW had done it but it was a prototype.

Dave

[Xenocide]

I went and dug around in my magazine stack, it was a center diff for an AWD rig that they were playing with, when you ran an electric current through the fluid it seized and caused the two plates to turn together... Thought BMW had done it but it was a prototype.

Dave

a ferromagnetic fluid i believe it is called. That is how adjustable suspension works on new cars from the inside. If you establish a potential across two sides of the fluid it will solidify.

[bryan413]

So Im not talking about the center diff. Im talking about the rear diff.

[Xenocide]

take it back, it will work, but if you have a manual it will be pointless. iX gear ratios were 3.91 for manual, 4.10 for automatic. 3rd gear will become your 1st gear.

[bryan413]

I have an auto.

[pdxmotorhead]

I can't see why it would not work. As long as the gear ratio is in the zone and it fits, it should be fine. You likely need to measure the width and compare just to make sure the "x" model does not have a unique rear diff.

If you can get it cheap enough its a valiant experiment at worst.

Dave

[Xenocide]

will lose low end tq and acceleration going from 4.44 to 4.10 or 3.91

[pdxmotorhead]

But the Auto by nature has more low end torque, it might not be too bad, Wonder if you could swap the ring and pinions on the carriers, reset teh gears and go that route? then you get he gear and the diff.

Hmm

Dave.

[Xenocide]

im sure you could, but then you would more than likely have horrible gear whine

[pdxmotorhead]

Not if they are shimmed correctly, I 4wheel as a hobby and we do gear swaps all the time...

I need to get a hold of a spare rear end, I want to take some measurements and see if I can adapt a different carrier into it for a better priced locker...

Dave

[cooljess76]

Not if they are shimmed correctly, I 4wheel as a hobby and we do gear swaps all the time...

I need to get a hold of a spare rear end, I want to take some measurements and see if I can adapt a different carrier into it for a better priced locker...

Dave

I installed "Genuine Gears" 4.56 ring and pinions in both diffs on my old '94 Jeep YJ. Shimming was pretty tedious, but absolutely necessary. It was nice to have 4th and 5th gear back:biggrin:

[pdxmotorhead]

Funny, I have a 94 YJ as well. :)

Axle gears get way too much credit for being hard, its like you said, tedious.

Dave

[cooljess76]

Yeah, the tedious part was having to press/pull the bearings each time you have to add/remove a shim. The second diff went much smoother once we developed a system. As I recall, some diffs are designed a little more "gear change friendly". I currently have an e30 medium case 4.10 open diff sitting in my garage with the cover bolts only threaded hand tight. I'd be more than happy to take any measurements for you guys if you'd like. Heck I'll even rip the guts out if anyone wants any parts out of it. There's nothing wrong with it besides being a non-LSD. I scavanged the cover, flanges and halfshafts for my e24 diff that I installed on the Ti. LMK if I can be of any help, not looking for any money or anything, I already got what I needed from it:wink:

[pdxmotorhead]

The trick is to use a old bearing and hone the inside out a little so it just slides on.

I've also found that if you keep the shims with the housing they almost always come out usable/dead on. The carriers are machined so accurately these days that the housing is the usual variable. Of course if the gears are really worn you may need to add a thin shim to the back side of each gear. There is a bit of eyeballing involved... :)

Dave