Differential Question

[sam3]

wondering what the Ix Touring (Euro) had for rear end gear ratio, we have several diffs from other e30's and can swap the gears if needed, but a swap of the whole diff would be easier. The IxT diff case is weeping and the tag is illegible.
Thanks

[Teaguer]

The Euro cars really did not have a set ratio as they could be ordered with a few optional ratios.
However all US ix came with a 3.91.

[supernaughtIX]

my 88 5spd euro IX touring is 3.91

[nando]

3.64, 3.73, 3.91, and 4.10 are the only possible ratios. 3.64 and 3.73 are early manual/auto ratios (euro only), 3.91 and 4.10 are later manual/auto ratios (universal).

[sam3]

3.64, 3.73, 3.91, and 4.10 are the only possible ratios. 3.64 and 3.73 are early manual/auto ratios (euro only), 3.91 and 4.10 are later manual/auto ratios (universal).

OK...Am I correct that any final drive will work because it's a completely separate axle, so if we opted for a more customary US set of gears we wouldn't screw anything up?

[nando]

no. you need matching front gears. there are only the 4 gear ratios I mentioned above.

[sam3]

no. you need matching front gears. there are only the 4 gear ratios I mentioned above.

That makes sense, sounds like I'm swapping out the gears. Thanks

[nando]

You cant swap gears. There are only 4 ratios that fit in the front diff. No other gears will work

[flyboyx]

i have been dealing with ix's for years. 3.73 is news to me. i have never seen or heard of that ratio in an ix. 3.64 was in a very very rare few early ones here in the usa. slightly more common in europe. likely if you want that ratio, it will likely have to come from across the pond.

nando is certainly correct in that the front diff MUST match the rear ratio. the reality is that generally if you have an auto, the ratio is 4.10, if you have a manual, you have a 3.91.

check the tag on the front diff.

all ix's use a viscous rear lsd in the differential where a standard e30 would be either open or the clutch type. the viscous can provide better lockup (supposedly up to 90%) under most conditions if it is in good condition.

i can't figure out why you want to entertain this thought? just put new seals in the diff you have, then call it a day.

[sam3]

i have been dealing with ix's for years. 3.73 is news to me. i have never seen or heard of that ratio in an ix. 3.64 was in a very very rare few early ones here in the usa. slightly more common in europe. likely if you want that ratio, it will likely have to come from across the pond.

nando is certainly correct in that the front diff MUST match the rear ratio. the reality is that generally if you have an auto, the ratio is 4.10, if you have a manual, you have a 3.91.

check the tag on the front diff.

all ix's use a viscous rear lsd in the differential where a standard e30 would be either open or the clutch type. the viscous can provide better lockup (supposedly up to 90%) under most conditions if it is in good condition.

i can't figure out why you want to entertain this thought? just put new seals in the diff you have, then call it a day.

I'd be happy if it were just the seals, the case itself is weeping, I think one good tap from a hammer and it would be in pieces, 23 years of road salt.

[nando]

Used front diffs are fairly cheap, check ebay.

[matt0300]

That's not true that all us IX's came with 3.91. Automatics came with 4.10.

[z122643]

So question. I'm thinking about replacing my rear diff. will any E30 rear diff do (with the same ratio) or do I need and iX one? Will the LSD of the M3 work?

[Jaxx_]

So question. I'm thinking about replacing my rear diff. will any E30 rear diff do (with the same ratio) or do I need and iX one? Will the LSD of the M3 work?

as I understand the mounts are the same for non-IX e30s, unsure about m3, but you will need the correct ratio. The differentials are clutch type in regular LSD e30 differentials and viscous in the IX.


If you're having problems identifying a diff you can do the calculation, however you need to be fairly precise if you're trying to find the difference between a 3.73 and 3.64. You can always do 10 turns and then calculate the half shaft revolutions from that, which is a better way to do it.

Also, keep in mind that the gears are matching sets, you can't just replace the ring gear, you need to also replace the pinion. The set is matched, so for example you can't use a 3.91 pinion with a 3.73 ring gear, they would not mesh. I'm sure there are exceptions but I wouldn't try a Frankenstein diff out. :)

[nando]

any medium case (type 188) diff that bolts into an E30 will work in an ix