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The carrier bearing part numbers listed in this thread are NOT for the stock LSD. They are for the truetrack, which has a larger inner diameter for the carrier bearings.
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Thank you for the clarification William. Since I'm staying stock LSD with a weir kit I'll use the 90368-45002 bearing.
 

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My delimna is the ring and pinion. I have been through 2 roaring/whining diffs and don't want to waste money on another one. My opinion is that they will last if you drive them on the street but if you take them to the dragstrip they just won't hold 400 hp after 5 to 10 runs. I have followed several posts and most of them are complaints about theirs whining also. My second one came from someone on these forums everyone raves about but it roared the day I put it in and after making a few runs at the dragstrip it started roaring so bad I was embarrassed to drive it through my neighborhood.

If I do decide to go back with the same thing (which I don't want to do), do we have a Toyota online guy we can buy the parts wholesale from?
 

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My used 3.73s have been super quiet behind 550+ horsepower even after track days etc. It is all in the setup, and I use a 80W140 gear oil due to the extra heat.
 

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I don't do drag racing much - more roadcourse lapping. Years ago I ran a 12.1xx at around 125 mph. If your replacement ring and pinion that 'roared' right after installation didn't have severe preexisting damage, then the set-up was not correct.
 

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Who set it up? There are a million DIY diff rebuild vids on Youtube, but you can not learn all of the ins and outs just from watching a vid. I do everything myself, except diff setup. I take mine to a buddy who is a Toyota tech and does these at work all day. I've done enough with him to be comfortable doing them on my own now, but when I have one that really needs to hold a lot of power, I'll be going back to him.
 

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Discussion Starter #228
Pinion preload is key to a quiet diff. Get it wrong, and it will howl like crazy! Carrier preload is important too, but most howling is due to the pinion.
 

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And contact pattern, especially if you are swapping different gears into your housing. I have found to get a good pattern on used gears you often end up with backlash on the high end of the spec, which is fine.

Pattern on both drive (especially drive) and coast should be as good as you can get it, and pinion preload needs to be accurate (recommend a solid spacer here). Side shim preload should be set so that the second 'washer' shim you install can go in about halfway by hand and tapped in the rest of the way with a brass drift and hammer. Backlash spec is .003 to .007 but I find used gears usually end up in the .005 to .010 range when the pattern is perfect. Any adjustment in backlash affects the pattern as well. Spec for the truck 7.5" diffs is .003 to .010

3.73s in my Supra ended up at .009 backlash with a perfect pattern both sides and are whisper quiet even with all the poly in my car and minimal sound deadening. Many track miles on that diff too - again I use an 80W140 oil and 'bellows' style sealed diff breather due to all the heat in a diff that only holds around 1 liter of lubricant.
 

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Update:

For those who have issues with the truetrac case being too 'short' and not a thick enough side washer being available from Toyota, you can put a shim under the side carrier bearing (between the bearing and truetrac before you press the bearing on). You would put it on the side closest to the ring gear if your backlash was still way out of spec, or on the other side if the backlash is in spec but you can't get a washer thick enough to get the proper carrier bearing preload.

Here are the shims I used (.010 thick ones are also available, I chose .020 to put me into the middle of the available washer thickness ranges when close to the correct backlash setting, based on how much backlash it had with a thick washer):

https://www.amazon.com/gp/product/B003A03P9A/

And here are some pics of where to put the shim. A good bearing puller is needed to remove a carrier bearing, and you need to make sure the bearing seating surfaces and both sides of the shim are very clean before pressing the bearing back on.

https://drive.google.com/open?id=16aAfzWBDmzJ1g0k_I5H1ssTRf9FYIfbn
https://drive.google.com/open?id=1S7-EZW4S5hNuWpHjbmi8KeR_100gDKq9
 

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Yep his diff is all within spec now. As shown though, I had to shim under the bearing .020" to then use factory size spacer washers when fitting the center section into the housing.
 

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So after Ryan (funkycheeze) was able to bestow his magic upon my differential, I discovered an interesting situation which I have not previously seen brought up before in this thread.

The stub shafts do not go far enough into the truetrac receiving gear for the clips to snap into place. Put another way, the stub splines are not long enough. What this means is that I am able to pull out the stub axles with medium effort as they are not locked into the differential housing.

A dude called Dustin did have this issue a couple years ago with a different differential:
http://www.celicasupra.com/forums/showthread.php?73383-Stub-axle-locking-clips-needed!!!&p=850643&viewfull=1#post850643

He discovered that LSD and non-LSD differentials have different length stub axles. The wording in that thread is a bit backwards - it's not 100% clear which of the stub axles is shorter - LSD or non-LSD. My differential was originally an LSD, and at least conceptually it makes sense that LSD stubs might be shorter due to the larger LSD centre section inside the carrier.

So off I go onto the internet and I verify that yes indeed, there are two stub axle part numbers:
https://www.toyodiy.com/parts/p_U_1985_TOYOTA_CELICA_MA61L-BLPQFA_4101.html
41334 SHAFT, REAR DIFFERENTIAL SIDE GEAR
41309-14010 W/LSD 2 $275.14
41309-22012 2 $262.05

I tried to find pictures on the internet of these parts with no success. But... check this out:
http://trdparts.jp/english/parts_lsd_mechanical.html
take a look at CELICAXX
"For vehicle with optional L.S.D., Exclusive side gear shaft required. (*4)"
and... *4 41309-22012 2 Toyota Genuine Part "0"

This looks to me like the TRD LSD requires open-diff stub axles! This would correlate with my suspicion that the LSD stubs are shorter.

So... does anyone have any open-diff stub axles they can compare with LSD stub axles? measurements of overall shaft and spline lengths to compare will be valuable.

I've been running my diff in this manner for two years with no issues, however I'd like to understand what options are out there.
 

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Discussion Starter #236
Makes sense. The diff I installed the true trac in was a 3.727 non-lsd from a Cressida. Mine locked into place without issue. The snap in place sound was clear as day when we installed the stub axles.
 

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William - mine sounds like it snaps in as well. I get a real solid metallic clink. It's just the stub hitting the receiver though.

Any chance you have photos of your stubs removed?
 

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Yup I have an open diff\pumpkin and lots of LSD diff\pumpkins too to compare. This would be weird if no one has run into this before. Most people would have built their trutrack equipped pumpkins from LSD ones.
 

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Discussion Starter #240
William - mine sounds like it snaps in as well. I get a real solid metallic clink. It's just the stub hitting the receiver though.

Any chance you have photos of your stubs removed?
Nope. All I have are the crappy disposable camera pics in the first post. Really wish I had a digital camera back then so I could preview photos and retake them if needed like I do now.
 
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