New source of Torsen T2 LSD's

GC89

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Jeff are there any diagrams showing what the upper air guide and air duct look like?

Damn it - This thread just gave me new unicorns to search for, I want that diff cover and cooling pipe now. I assume a usdm case can just be drilled and tapped to fit the cooling pipe?
 

Piratetip

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Jeff are there any diagrams showing what the upper air guide and air duct look like?

Damn it - This thread just gave me new unicorns to search for, I want that diff cover and cooling pipe now. I assume a usdm case can just be drilled and tapped to fit the cooling pipe?
Unfortunately no.
The cooling pipe is bolted vertically to the differential case.
The diff case itself is a different casting, shape and more maching processes.
To accept the cooling pipe going down into the oil bath.

The only part that will bolt to our USDM differentials would be the rear aluminum cover with the extra cooling fins.
Similar design to the MKIV large pumpkin rear cover.
Its a really cool piece, I would like to have one as well :D
 

GC89

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Well if you win the lotto twice and find two count me in!

Being the diff expert have you ever tried or given thought to fitting a cooler to our diffs? I recall saving some pictures of someone who had done it but cannot find them now.
 

Piratetip

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Yeah I have thought about it.
Though I would need to take a log of the temperature inside the differential first.
Need to determine how hot the differential gets first, then based on that decide if its even worth running a cooler.

There are 2 ways I have thought about running a cooler loop.

1. Use the rear fill plug as an oil return fitting and drill a 2nd hole down lower in the rear cover for an oil out fitting. (may need to make a hole in the rear sub frame to accommodate)
Use a small dedicated electric oil pump triggered by an aftermarket ECU measuring Diff temp, or trigger the pump with a thermostatic switch on a relay.
Place a small oil cooler in the air path somewhere under the vehicle or mount it horizontally up out of the way with a small fan attached to the face of it.

2. Everything else the same except route the oil feed back into the differential up in the front located through the case directing flow at the pinion bearings.

The diff would then probably take 1/2 quart more fluid.

Unless your climate is 100°F + all the time or the vehicle spends most if its time racing at the track its probably not worth the time.
Only other application would be if its spends a lot of time at very high speeds, then I would route the oil up toward the pinion bearings.
They can become starved of oil at high speeds & would be good to send a dedicated feed up to them.
 

Jeff Lange

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Agreed.
This would be good to see and catalog.

Jeff can you bulk download all the TSB's for all 87-92 Supras?
Would be nice to have a backup of, and most I have not even seen.

I will dig through my Alldata and see how many are listed on that platform.
I can see about finding some other TSB's. There really aren't that many that are as interesting as the differential one to be honest. Most are lame, haha. The one about the power window switch is alright though.

Jeff
 

suprarx7nut

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I can see about finding some other TSB's. There really aren't that many that are as interesting as the differential one to be honest. Most are lame, haha. The one about the power window switch is alright though.

Jeff
Well we're an easy crowd to please!
 

Piratetip

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Spline count and spline diameter yes. The bolt face position is the same.

Circlip groove depth should also be the same, but I haven't personally verified it.

Jeff
Just to follow up on this discussion.
I have verified that the Lexus T2 Torsen is not a drop in part to the MKIII.
I have a solution to correct for the issues, but still need to do the work on one of my upcoming rebuilds.

That or someone would have to find the Japan only stubshafts they used for the MKIII Torsens.
There are none floating around, so option one is the only choice.
 

Piratetip

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The issue lies with the stub axles, otherwise works fine.
I will alliviate the issue and make it work. :)
 

Dave 1jz

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So The BRZ/GT86 use the shorter LSD pack stub axles?

There are some JZA70 torsens around, but not much for sale, i agree. I have a hybrid MA70/JZA70 3.7 torsen mounted now. So this indicates i could mount a IS300 T2 in this one.

I you could extend the shorter shafts or machine a extra groove in the carrier, then it fits in the MA70 diffs
 

Piratetip

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I don't know how it relates to the BRZ.
Just working on the Lexus T2.
I would have to have both in hand to compare them.
 

Piratetip

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I bet they do fit.
But you won't be able to bolt our drive axles to them.
Output flanges aren't anywhere close to the same design.
 

andrew_mx83

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Is there a bolt in option from the truetrac range? They definitely do they for the solid 8" diff.
Is the toyota version any better or worse than the truetrac?
 

Piratetip

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There is no Truetrac that fits the MKIII.
dr.jonez looked into that a long long time ago.

I don't remember what the issue was exactly, but I seem to remember a clearance issue.

I can and have swapped Truetrac lsd's into MKII differentials though. Those work.

As far as difference between the Toyota torsen and the Truetrac torsen.
Similar designs, just different ways of going about it.
I will post up some information at some point.
The Toyota torsen is noticeably heavier than the stock multiplate clutch LSD.
 

Piratetip

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After digging around for awhile I think I figured out why Truetrac does not work for us.
The PN that would work (613A610) is only for the solid axle trucks.
The side gears have no groove machined to their inside to engage with our IRS circlip stub shafts.
So with the right measurements and a lathe (with hella freaking hard cutting bit CBN) you could make it work, just need to cut ramps.
Otherwise you will never be able to pull out the stub shafts ever again :).
But if you don't cut a groove, the half shafts will probably slide out too far during operation and puke out oil everywhere.

The MKII has a drop in Eaton because they list and made it that way originally.
In their catalog they list fitment for Celica, so they added the circlip groove for the IRS fitment.

Some reading on internal differences to the Toyota T2 and Eaton Truetrac.

Toyota T2:
Uses "Equivex Parallel Gear"

Eaton:
No fancy patented name. Just "helical-gear style".

If anyone ever wants to try to put one of these into their MKIII I would be up for the task.
I'd like to confirm they actually DO work.
 

Piratetip

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Some photos.

T2 Test Fitted into the MKIII Pumpkin, no issues.


A look inside the T2.
All the guts come out as one shot, you can't take just 1 gear out, they are all interlocked together.
But watch out if you do, the gears all go flying!
The trick is to stand it on end and let them all sit flat.

Honestly the T2 feels really stout, all the components are very heavy and feel very well made.
Last couple images are showing the T2 side gear next to the stock LSD side gear.
Just taking some measurements for the parts I need to modify.
Hardly any wear marks against both end plates, or wear marks against the side case where the small outer gears spin.
This one supposedly has 140,000 miles and still looks brand new IMO.

 

Piratetip

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So I have completed fitting the T2 from the Lexus into the MKIII diff.
Works fine, no issues now with the stub shafts.

Good to know there is another Torsen option!
Much much stronger than the old T1 from the JZA70.

It can of course handle much more abuse, but of course the driving characteristics are slightly different between them.
And different of course than the MKIII stock clutch style as well.
 

Dave 1jz

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Great news! Did you machine anything to fit the LSD type stub axles?

Are they easy to source in the US?
 

Piratetip

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Yes on both.

There are a couple on eBay right now.
 

Piratetip

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Took some weights.
Stock LSD carrier - 17lbs
Lexus Torsen - 20lbs

This is not including the carrier bearings.

So quite a bit more material and wall thickness on the T2.
Not suprising since the internal components are noticably large when I have them in hand.

I'll be stuffing this T2 into one of my cores in the near future.
Thinking about using 3.73 gearing unless anyone has any requests for something different.
 

A70nut

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Have you done any in car testing yet to see how the car drives with the t2 torsen?
 

Piratetip

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Nope.
But there are a lot of vehicles that use this style T2.
The driving characteristics of T2 Torsens are already well documented.
 

Piratetip

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You could ask Jeff what he thinks of the T2 driving characteristics. @Jeff Lange
He swapped one of these Torsens into his Lexus.
 
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Piratetip

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Hey at least someone managed to find one !
 

Jeff Lange

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I don't know how it relates to the BRZ.
Just working on the Lexus T2.
I would have to have both in hand to compare them.
The BRZ/86/FR-S use the exact same part as the Lexus, so it will be the same as far as that goes.

What modification was required to the stubs? Did they just need to be shortened, or was there something else?

I've driven with the T2 in a few different cars now over the years. The IS300, my IS both with the 2.5L and 3.5L, the FR-S/86 as well as my ice-racing Previa and others. I've been extremely happy with it. Much better than the T1, more predictable and better balanced. Great for grip and keeps torque transferred much better than the T1 in low-grip situations as well.

Jeff
 

Piratetip

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Stubs need to be extended.
Otherwise they have the possibility of diving too deep into the side gears.
Then at a minimum would start grinding the dust shield into the side of the case or damaging the side seals.

Thanks for the info on the driving characteristics of the T2!
 

Jeff Lange

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Interesting, but also good to know. The only T2 I've got tagged for an A70 is going into a TT-R that already has a T1, so I'm hoping they should fit fine.

Jeff
 

Piratetip

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If it had a T1 then it already has the longer stub shafts.
Will go together with no modifications.
Those longer stub shafts are not easy to come by.
Which is why I just made them myself. :)
 
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Dave 1jz

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You could also make the extension pieces from used stub axles. As long as the groove for the clip is in the correct position
 

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The standard non Torsen Mk3 stubs are 6mm short, so the dust shield of the stub will rub on the side of the housing and damage it and the seal. To lengthen the shafts by 6mm so the tip rides on the internal stop of the Torsen, just weld a 6mm thick washer stack that has an OD smaller than the spline ID of the Torsen to the end of each shaft. The circlip is in the correct place and the shaft extension does not need to be splined, it just needs to hit the internal stop before the side shaft rubs. I also sanded the end of the washer stack flat and true.
998753DE-167D-42FE-B81F-9F2DC010AB89.jpeg
 
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Hybrid

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Well did you get the rear cover in yet? :D
Haha I did Nick. Just in the process of cleaning it up, it's also had its top fins modified, which I didn't realise but can now see in that pic. I'll be repairing those also.

It had several coats of paint, powder coating and oil. Has taken some time to media blast it all off.

One thing I will say, which I can see in that guys original pic, the casting that was used was very unrefined. There is so much casting junk in it compared to the normal diff covers. My guess is it was a last minute part decision to produce. I have spent a lot of time smoothing out all the defects. 94119701_10160062260934466_6422838791886602240_o.jpg 12814058_1035948436478657_3017388443647847429_n~2.jpg
 
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Piratetip

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Good to note.
How is the finish on the inside compared to a normal one?