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The Chubby Chaser

X90 Ring & Pinion Backlash and Runout

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I am swapping out my torsen and 3.7 for a trd 2-way and 4.3. Does anyone know what the backlash and runout is supposed to be on an X90? I searched and can't find anything X90 specific. It's not written on the ring gear either. I have found specs for a Supra.

 

http://www.max-boost.co.uk/max-boost/resources/SUPRA_MKIV/DIFFERENTIAL_AND_AXLE_SHAFT.PDF

 

I want to be as accurate as possible because I have heard your ring and pinion can get chewed up if you get it wrong.

 

Thanks!

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Guest DuaxMachine

It is set-up the same way as all 8" Toyota diffs.

But your opening a can of worms if you don't have a full sellection of pinion shims, and a shop press to change them,

because each pinion needs to be checked for height from the diff bearing bores.

That's hard enough if you have everything, but without having all the shims, and the measuring tools to set it correctly, your up a creek without a paddle (an old way of saying your fucked).

 

The diff bearings must be tight enough to take all slop out, plus a little bit of preload.

On the Mk3 & X8, where you slide shims in and out from the rear, the book calls for it being just tight enough to have to tap the shim in with a plastic hammer past the 1/3rd point.

 

Gear backlash should be right around 5-7 thou. (.005"- .007")

 

Do yourself a favor, take it to a shop that has done the Toyota diffs before, and let them set it up.

You just half ass set it up, it will be noisy, and turn your gears and lube into silver oil paint.......

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Guest DuaxMachine

Where did you find that fucking hillbilly instructions at ?

There is so much fail in that garbage it's unbelievable.....

Pinion tightness needs to be adjusted using a small torque wrench, not a dial indicator.

 

Oh, by the way, since you are not going to be driving this like an old lady, replace the 'crush sleeve' with a solid pinion spacer.

They are about $25, and use shims to get the pinion bearing preload correct, and they will not fail like a crush sleeve.

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Thanks!

 

The bitch of it is that I highly doubt there are any shops around that have done toyota diffs before. It's all American trucks around here. That won't stop me from looking though.

 

I have been fucked over by shops before, and would much rather do something myself or have a friend do it. My friend Omar owns a shop, and I usually go to him with anything I can't do myself. However, he has never worked on toyota diffs and told me he wouldn't/couldn't do it.

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I just bought that, planning on changing it myself... Damn :/

Dint know of any shops around my area so we'll see how it goes

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Guest DuaxMachine

They are like any other, but you will probably end up buying more shims than you need at $8 a pop from Toyota.

In case you don't have it, here is the TRSM for the Mk3 Supra:

http://www.cygnusx1....K3/default.aspx

 

Follow it to the letter.

Forgetting to do something as simple as whacking the bearings with a plastic hammer after installing a shim will effect gear mesh.

I found that out years ago......

Had to go into it a second time.

Bottom line, if you do your best, and it makes noise, just pop it out and do it again.

 

If you can't find the solid pinion spacers, let me know, but I am sure any of the truck people have them.

Just look for the ones meant for the rear diff on a V6 8" rear end.

Make sure everything is spotless, as the least little bit of dirt, or a thread from a shop rag will effect testing the pinion pre-load.

And I am not talking about tightening the nut..........

After the pinion is installed, you test bearing pre-load by putting a small torque wrench on it, and seeing how much force it takes to turn it.

 

I hold the pinion from turning when tightening the nut by wedging a chunk of aluminum inbetween the gears.

It's soft enough not to hurt the gears when you torque the nut.

 

Have fun........

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Guest DuaxMachine

Too bad you guys aren't local.

I keep all the shims in stock for the Toyota 8" diffs, and charge a pitance to set diffs up for people.

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Guest DuaxMachine

Doesn't matter, no 2 housings, gear sets, or diffs are the same, and when your talking just a few thousands from good to fail,

the chance of getting it even close without changing shims is slim & none.

 

If it ever happens, you better run right out an buy a lottery ticket ASAP.

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Thanks! It's hard doing things right. Especially coming from 240s where you just throw the diff in and say fuck it.

 

They sell diff setup kits for $100 to $150 that come with new bearings, shims, pinion seal, and marking paint. Should I drop the money on that or just use the existing stuff? My pinion seal and shaft seals haven't been leaking, but they do have over 100k miles on them and are 16 years old....

140386-1-k.jpg

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Guest DuaxMachine

New seals are the only thing I would buy, besides shims.

Now if your diff was sitting with water in it, and they are all pitted, that's a reason to replace them,

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Guest jesus

i cant offer advice as to the "spec" for it... however i just had a shop change my diff gears from the stock auto gearing to 4.3's and i duno but i dont like it :S.... the car certainly has abit more downlow but "to me" it feels to smooth now with a 3076 built 1j running 20psi it should feel stupid but it honestly is harder to maintain it on boost when sideways, it feels like the engine isnt loading up good enough... i was previously making 282rwkw on 15psi, i rebuilt the motor/ported head and ti valve springs and it made the exact same power on 20psi with the 4.3's...

anyone explain that cause im fucked if i know lol

 

p.s where did u get solid bush's for ur x90?

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Guest jesus

Buy better tires.........

 

its not wheelspin... a rebuilt 3076'd 1j with cams should do more then 280kw on 20psi.. but yea ill stop hi jackin

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New seals are the only thing I would buy, besides shims.

Now if your diff was sitting with water in it, and they are all pitted, that's a reason to replace them,

 

When you say "shims" do you mean the ones that go on either side of the diff bearings/caps near the axle holes or do you mean the pinion shims? The solid pinion I bought comes with shims. If it is the latter, do you know where I can buy them? I have only seen them in that kit I posted.

 

I found a shop called Axle Boy about an hour west of me that has received very good reviews. They normally work on Jeeps, and they build off-road ones, so I think they can handle it as long as I give them the runout, backlash, torque, etc... specs

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Guest DuaxMachine

Sorry, forgot WTF we were talking about, but yeah, a sellection of both are needed if your swapping the pinion,

and I am not talking about the ones that come with the crush sleeve.

The shim that sets the pinion depth is under the bearing that stays pressed on the pinion shaft.

They are all available from Toyota.

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Ugh. This "simply" diff swap is getting quite complicated. So, you basically have to take the pinion bearing off, put a shim in, put it back in the pumpkin, measure the pinion depth, then take it out and take the bearing back off and use a different shim if the depth isn't right? Jesus christ!

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Guest DuaxMachine

And jesus fucking krist, I wasn't fealing well last night, so I let you slip,

But don't start that fucking TC.net shit of coming in, and completely changing the fucking subject.

OK, so your 1JZ is loosing power......

That means it's dying, just like the 7M you had before it.

Big fucking deal.

Gear ratios have nothing to do with power loss, or reduced fucking boost.

9 fucking posts, and you are already becoming a pain in the ass.

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