Differential Dilemma

[supradjza80]

Guys,

As a few of you know I have purchased a Torsen Differential from an IS300 and I am going to be tossing it into my MA70 diff pumpkin in the next month or so. I have just started to go through all the parts needed and I am running into an issue with pinion and carrier shimming.

I have attached a pdf which shows all the differential parts and prices. Now since I am putting a different carrier into my MA70 pumpkin I assume that I may need any 1 of the many shims listed to get my backlash and gear teeth wear correct. Since I do not want to purchase 1 of every size of each shim so that I know I will have the correct size (shims are special order and will take 2 weeks to get from Curt at Elmhurst Toyota) I am not sure what my other options are. I don't want to get the diff all apart and be unable to get it shimmed correctly. What have others done in this situation, is there an aftermarket manufacturer who sells shim kits for a lower price than toyota (all the shims would be ~$200, and I really only need ~$20 worth of shims once I know the size)

Question 2 - I would like to re-use the bearings that are on the lexus carrier and put them into my MA70 pumpkin. Now I know the bearings are the same size but I am wondering how much of a problem it would be if I do not change the bearing races from the lexus pumpkin to the toyota pumpkin? They obviously have different mileage in them and will inevitable have slightly different wear, but if all bearings are in good condition does anybody see a problem with doing this?

Question 3 - Are the pinion front and rear bearings the same from the IS300 pumpkin to the supra pumpkin?

Any help on this will be greatly appreciated.

 

[IJ.]

Did you get the Torsen Stub axles Dave?

 

[supradjza80]

Its the is300 torsen, so according to what I have found no stub shaft changes needed. But i have the whole lexus pumpkin, including the stub axles.

 

[IJ.]

I know the A70 Torsen and LSD uses different axles Dave, NFI on the is300 you're the pioneer with this one

 

[supradjza80]

I know the A70 Torsen and LSD uses different axles Dave, NFI on the is300 you're the pioneer with this one

Well actually it looks like gofastgeorge did it first and he had no issues with fitment or stub shafts - I am sure he will chime in. The same TRD diff is used in the IS300 and ma70 so everything looks to be a go.

Beyond stub shafts I am hoping someone has better option for me than just ordering a shit ton of diff spacers that I do not need.

 

[streetracer_258]

The normal way would be to assembly the diff and inspect tooth contact. Pull apart insert shim rebuild and re-check alignment. Repeat until you are happy or its within specification. My bro works for a guy who rebuilds old F1 gearboxes and he can tell you at a glance what size shims he needs lol.

 

[supradjza80]

The normal way would be to assembly the diff and inspect tooth contact. Pull apart insert shim rebuild and re-check alignment. Repeat until you are happy or its within specification. My bro works for a guy who rebuilds old F1 gearboxes and he can tell you at a glance what size shims he needs lol.

Right, I am just trying to see if i have any cheaper options to get all the shims so I know I will have the correct size.

 

[gofastgeorge]

Yes, the IS300 helical LSD fits using the standard shafts.
I have done 2 now, and other than playing musical shims, it is not a problem.

On shims, all I can say is 'Good Luck'.....
Even when I think I have the correct shims in, when I do the TSRM 'whack it with a big dead blow hammer' thing, it will move slightly, and end up taking a different shim.
If you don't do the 'whack it' thing, and you think everything is right, when you torque down the bearing caps, things move, either right away, or 10 miles, and a heat cycle later.
(forgot to do it once, and ended up pulling the rear end again because of the gear noise.....)

Anyway, visit all the scrap yards you can to gather shims, or find a transmission/rear end shop that may have something,
or do your best guess, and be prepaired to order shims again.
I finally broke down and ordered about a dozzen shims that I didn't have.
And also, Honda/Integra-R shims are the correct OD, but the ID is too small, but will work if you open them up.

Oh, and at least the Lexus inner bearings match, I have not ever changed any of them out.

 

[IJ.]

Great info thanks for posting George!

On average how thick are the shims required?

 

[gofastgeorge]

Crap, I don't remember, the last one was 5 months ago.
I just keep all my shims in order by thickness, and go through them as I set up a diff.
I do remember, all the really thick ones I ordered, were not used..........
I ended up with using ones that I had collected over the years.

 

[supradjza80]

Thanks George for the information. I talked with Curt at elmhurst and I would pay a 20% restock fee on any unused shim. While this sucks it is not unreasonable considering they have to be special ordered and take 2 weeks to get so I think I will be spending about 225$ on the shims. Hopefully I get it right the first time when I put the diff together.

Does anybody know of a good aftermarket source for the carrier and pinion bearings, or have the aftermarket part numbers? Still have not decided if I am going to replace these or not.

 

[gofastgeorge]

Sit the thing in the housing first, and see how far off your stock shims are.
You may just need to order a few, or if your really lucky, none.....
You could always offer to sell your unused shims, as your not the first member to run into this glitch.
Damn RX-7s, Miatas, & AE86s have threaded side collars, and don't require shims, just a spanner wrench to set them up.
I can set gear mesh on one of them in about 10 minutes.

 

[supradjza80]

George, it would be best if I could have the diff out first to check what shim I need but I won't be able to have the car down for that long to wait the 2 weeks for the shims to come in. The car is in storage right now so I also can't do it until I get it out in about 2 weeks. I am also trying to get everything done quick so that I can iron out any kinks before my first track day (Road America) in the middle of April. The diff is one of a few things I am planning to do to the car.

 

[IJ.]

Buy another cheap a70 Diff and build it all into that then when it's done swap it out in a day?

 

[Poodles]

Yarp, the miata is a typical 3rd member. The case is all once piece on ours making the shims a pain.


But hey, at least our oil seals are easy to do without screwing up the preload as you can replace the crush sleeve without pulling everything apart...

 

[supradjza80]

Sit the thing in the housing first, and see how far off your stock shims are.
You may just need to order a few, or if your really lucky, none.....
You could always offer to sell your unused shims, as your not the first member to run into this glitch.
Damn RX-7s, Miatas, & AE86s have threaded side collars, and don't require shims, just a spanner wrench to set them up.
I can set gear mesh on one of them in about 10 minutes.

Thanks for the tips. Quick question for you, did you re-use the lexus bearings or did you get new ones in your diffs? If you did use the lexus bearings did you transfer the races into the MA70 housing?

 

[Poodles]

The races come out when you pull the diff out.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=RA&P=31

Races are matched to the bearing, don't mix them (this goes for new too).

 

[gofastgeorge]

Races are matched to the bearing, don't mix them (this goes for new too).

Nope, old wives tale.
Timken, and other tapered roller bearing manufactures sell the inner bearing assembly, and the outer race seperately.
Sundstrand (the people who make half the hydrostatic transmissions for heavy equipment on the face of the planet)
say to only repace what is needed when servicing their product, and there is no problem in replacing just a race, or just the bearing assembly.
I have been mixing them for years, on all sorts of equipment.
Maybe on something like a turbine, where it is turning 10,000 rpm,
but a diff bearing is lucky to see 2000 rpm (6500 rpm in 5th gear, or way faster than most people ever go).

But if it makes you feel better, go for it. It's not my time or money

 

[Poodles]

Well, he's pulling them out anyway

The TSRM says to label them as to not mix them up as well.

 

[supradjza80]

The races come out when you pull the diff out.

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=RA&P=31

Races are matched to the bearing, don't mix them (this goes for new too).

yeah I wasn't thinking when I posted that up, I have been through this section so many times I am loosing it .

George, did you compare the pinion and ring gears between the IS diff and the Ma70 Diff? Did you notice any differences (part numbers are different with toyota)? I know the bearings are the same but I am not sure about the gears them self. The IS diff I purchased is also a 3.73 rear end so if the ring gears and pinion are the same it would be nice to just swap them and not have to swap the ring gears.