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q45 r200 ring gear interchange?


yessir

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i currently have and early 90's q45 vlsd(3.54)and im trying to get a numericaly lower gear ratio. I was wondering if anyone can tell me for sure what ringear will fit my diff keeping my current pinion, such as and automatic 350z r200 ect.

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Either the OS Giken 3.05, or the very hard to find R200 3.36 from a 1974 S30 2+2. Not sure if it came with manual or auto trans, but it is pretty damn hard to find one. You will need the matching pinion. They must go in as a matching set.

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Wouldn't it be easier to just buy the auto 350z/G35 diff? You can get one out of an Infiniti for sure for like 250 bucks, and those 3.357 for the autos. Just make sure you get one that actually has the lsd option, not all of them do.

 

You want lower than that and you'll probably have to order a non-oem gearset, or try a differential from a non-Nissan. Lots of American cars have lower gearing for sure.

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The much easier thing to do is swap the LSD into the diff that already has the gear ratio you want (assuming they swap--don't know much about the shortnose units). You might try asking SATAN. I think he knows quite a bit about those shortnose units.

Edited by JMortensen
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I'm pretty sure the solution involved swapping both the LSD unit and the output axles from the Q45 into the diff you want. You have to do this because it's a VLSD unit and the output axles are longer or something.

 

Don't quote me on that but I'm almost positive this is true. You also have to worry about the whole "12mm vs 10mm" bolt thing...but that's a pretty easy fix if you have a tap and die set. (the thing I'm talking about is the bolts that hold the ring gear onto the lsd unit)

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I'm pretty sure the solution involved swapping both the LSD unit and the output axles from the Q45 into the diff you want. You have to do this because it's a VLSD unit and the output axles are longer or something.

 

Don't quote me on that but I'm almost positive this is true. You also have to worry about the whole "12mm vs 10mm" bolt thing...but that's a pretty easy fix if you have a tap and die set. (the thing I'm talking about is the bolts that hold the ring gear onto the lsd unit)

I think you're right about the VLSD having 30 splines vs the normal 29, but the diff stubs should swap out no problem.

 

The issue with the bolts is that the ring gear has the threads, and it's a blind hole. Can't tap it, and the metal is hard as hell anyway. I think I've read that some of the shortnose diffs have 13mm bolts. That's really fuzzy, so someone with experience should really say for sure (again, I think SATAN has some experience here and that guy knows his stuff), but if you have a 13mm ring gear hole and a 12mm LSD, then you can't get the bolts through the LSD and into the ring gear. It would probably be a fairly easy task for a machinist to open up the holes if that were the case.

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I understand this, the holes in the ring gear are 13mm, and the holes in the lsd unit are 12mm.

 

You obviously can't put a 13mm bolt though a 12mm hole, but you can put a 12mm bolt through a 13 mm hole.

 

If you had some sort of spacer that was threaded on both ends to essentially make your 12mm bolt, 13mm for the part that goes through the ring gear.

 

Would that be possible, or would the spacer be far too thin and just crumble?

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The blind holes with threads are in the ring gear. If you're talking about putting a helicoil in the ring gear threads to make them 12mm, I don't think that you could get one that would only step down 1mm, but even if you could, I wouldn't do that on such a crucial fastener.

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please excuse my dumb question but what is a "blind hole"?

 

Doesn't go all the way through the material. So in the case of the ring gear the hole might be 3/4" inch deep, and it's threaded all the way down to the bottom. Basically means that you can't tap it because the real threads on a tap don't start until 3/8" or so up the tap.

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