edinlexv8

iTrader: (2)

Hi guys,
Been doing some work on my diff to swap the centre with a torsen LSD from a supra. I put up this thread to update you all about this and possibly get some advice if I get stuck. But I am stuck at step 14
SA100 - 14. Check Minimum Backlash. Any advice would be very much appreciated!

Started off by pulling the diff out. The one highlighted in yellow is the one I bought for this conversion. It is a post 1997 Supra TT diff centre which is 8" (same as the soarer diff centre). As I will be using the same crown wheel and the pinion, the teeth being 47 and 12 respectively the final gear ratio would remain the same as 47/12 = 3.917

















































Now coming to step 14 in the tutorial, I need to do shimming and find the right shim to fit in the LSD so that there will be minimum backlash. (SA100 - 14. Check Minimum Backlash) No idea how to get this done???

UpInTheLex

iTrader: (5)

Glad to see you got the diff in. Did you put some compound on the gear teeth to check the contact pattern?

Is that a caterham super 7 in the background?

Any MKII Escorts around the shop? I wish we had those here... I'd be all over one. The closest thing is probably a volvo 240 or a Merkur XR4Ti ( Ford Sierra to you guys)

Hey also I wanna see more videos with Scottish accents. I've talked with some drunk Scotsmen that I couldn't understand a word of what they were saying.

Maybe a good burnout video??? Hmmmm.....

Here's how I celebrated my new diff
Check this out!!
http://www.youtube.com/watch?v=yc7tCgF9qi0

edinlexv8

iTrader: (2)

Well spotted mate! Yeah the ones in the background is a Chateram.

Good burn out video! I have no idea hwo you did that tho! may be some advice would help me put up a video like that (if I dont crash into anything trying it!)

Coming to the contact patter, as the crown wheel and the pinion still are one set the contact pattern seems to be fine. My biggest issue with the new diff centre is we see no backlash at all. From the manuals it is very clear that there should be approximate backlash of 0.05mm. Having no backlash will create problems at high temperature when these metals expand. So need to shim the diff for the right amount of backlash.

Also put up a tutorial thread for other to work on here:
https://www.clublexus.com/forums/sus...ir-manual.html

UpInTheLex

iTrader: (5)

True, as you said, you haven't changed the pinion and reusing the same ring gear so the contact pattern should be all good.

My book says to Measure at 3 locations and the average should be .0031-.0051 inches. The max and min values should be within .0020 inches of each other.

Replace the adjusting plate washer on the ring gear tooth side with one of a different thickness to adjust backlash. It spaces the bearing race in or out. The ring gear tooth side should be the drivers/left axle side.

I believe it's located underneath of the outer bearing race in the differential carrier retainer. On the left axle side. See the pic.

You need to go thinner(I think) to get more backlash. You're loosening the rear up a bit, and you'll also loosen the preload on the bearing a bit.

***Since you are so close, I would just try pressing the outer bearing races into the differential carrier retainers a little more.***

edinlexv8

iTrader: (2)

Some final pics of the diff rebuild folks,





After a lot of scrubbing with awire bush and generous use of hammerite!


Measuring the backlash with the guage






Diff rebuild is complete and is ready to go back onto the car

wheels 2

iTrader: (1)

If you were to change the differential gear form 4.083 to 3.266 wouldn't the mph on the gauge cluster be off?If so how would you fix it?

CLNSC3

iTrader: (4)

Good information in this thread! My car desperately needs LSD!

edinlexv8

iTrader: (2)

My gearing was still 4.083 as I used the same pinion and the crown wheel from my open diff. Check the following image


The ratio of 4.083 comes from the ration of teeth between thw crown wheel adn the pinion. I would suggest you use the highest ratio to get the fastest acceleration from the auto box though this would reduce the top speed. Choosing a lower ratio of 3.266 will increase your 0-60MPH time though you can get a greater top speed but your speedo will be out.

Also just to keep things clear this ratio of 4.083 means that for every 4.083 revolutions of your engine the crown wheel revolves ones. If the crown wheel revolution has a 1:1 ratio with the wheel/tyre the for every 4.083 revolutions of the engine your wheel does one full revolution.

wheels 2

iTrader: (1)

Ya I know how the gears work and stuff.But i was wondering if you did change it how would you get the speedo right?

Da Coupe

iTrader: (7)

Great work! I'm alittle confused though. I thought all 6spd diffs were the same and didn't fit our SC's. But the 8" works? Is there a marking on the diff to distinguish between the 8"/8.7"? Which year TT's came with the 8"?

5sp_jzz30

iTrader: (2)

not 100% on what you are saying. you cant just press the bearing races to get more clearance. nissan diffs work in that fashion where the adjusting shims are on the carrier bearings and not at the pinion gear. to adjust the backlash you are essentially moving the whole ring gear/carrier assembly over to one side or another by thousands of an inch. to move it to the left you replace the left shim with a thinner one and the right one with a thicker one. you dont loosen it up. you that way you get terrible whining

toyota dont work that way. on toyotas the only form of adjustment is by pressing out the pinion gear and pressing in a new adjusting shim into the differential housing. the side bearing races on the carrier bearings should not be touched and will get damaged if you try to "move" or modify them.

the way i test a diff is i set it on the table and then lock the pinion shaft(input shaft) and prevent it from spinning. you do not want it to move at all!!! then you set the dial indicator on the ring gear tooth. then take a wrench and put it on the ring gear bolt. try to move it and look on the dial indicator. you should see some needle movement before the diff tries to turn the pinion gear hardcore.

its the same testing as the nissans ive done and my boss' 67 saab 850 monte carlo bnneville salt flats car

btw i would worry about backlash that much. toyota is really adamant about their machining and its very precise. i have done 2 lsd swaps. one was a tomei techni-trax in ILLROLLERS car and one stock torsen. i didnt even change the backlash. i just checked it after reassembly and it was all within spec.

2+ years of drifting and ILL's SC is still good(knock on wood lol) and the other one too.

good luck and good work

jdm93400

so this is for sc400