Brent's Toyota Drift Car Gets New 5.13 Gears In The 6.7" Differential
(55 BIG pics loading)
NOV 15 2018

Brent's 87 Corolla is using all 100 horses as he drifts around the corner here at the Musselman Honda circuit in Tucson. Lincoln Locker spool in the rear means 50 horses per wheel all the time.
The 4AGE engine runs on Yamaha R1 carbs. Another popular place to drift is Wildhorse Pass up in Chandler AZ.
Brent did a drive-by and brought over the 6.7" with all the good stuff. His diff was very noisey and upon removal this tooth was gone.
No surprise this tooth went bye-bye after you read farther down ;)
The pinion flange had about 20 or 30 thou of in/out movement.
The pinion nut is so far down on the pinion threads that there is almost no groove for the dinged nut to grab onto. Wonder what is causing that.
So if you have a 6.7 or a 7.5"....or even an 8" diff then you can get the bearings, seals and solid collars from Spence at Weir Performance
Here's the bearings and seal....carrier bearings on left...big pinion bearing and seal in middle.... small outer pinion bearing on right.
New 5.13 gears and parts organized. The gears came from Weir, too.
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Lincoln locker. Spools are not available yet for the 6.7....gotta do what you gotta do. Whoever did this did a very nice job of MIG welding it.
Pre-checking the feel before this teardown begins....still a little bit of carrier bearing preload left.
This is that up/down travel that is a killer of ring and pinons.
Drop the old 513 ring gear.
New carrier bearings will be tapped on.
Here's a close-up of that MIG weld job. As far as the quantity of welding material....this guy did not hold back.
Overall, a much better job than I have ever seen on other welded center carriers.
Still, that must have been alot of heat moving around so a quick run-out test showed that all was still in spec. Only saw .0015" runout max.
Surfaces were tested with a big flat file and all was good.
Red Loctite will be used on the 8 ring gear bolts.
70 ft/lb of torque.
Now let's move onto the outer bare diff shell...
Bang the old pinion out/remove the seal and old races.
Reason #1 for all the gear noise and broken tooth.....No pinion shim. Zero. And no hidden shim behind the inner race. That would also explain why the pinion nut seated down too far.
New BIG inner race is tapped in.
Small outer race is also tapped in.
Now onto the pinion portion. The first attempt with 078 resulted in a very shallow yellow painted pattern.
Teardown and now trying 094.
Drive......much better but still shallow.
Coast
Pinion tooth....you can see the lower comet tail is strongly tucked into the tooth root.
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Teardown and re-shim to .102
.102....... beautiful! Good depth and even favoring the toe end some. Nice.
Coast. Nice.
Reverse painted Drive.
Reverse painted coast.
Now see where the comet tail is? It moved out of the root and almost to center. Ideal.
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With pinion depth established, now to get the high quality Weir solid collar shimmed correctly. The same solid collar and .045" shim from the previous job was used again.... and resulted in the exact same sloppy in/out movement as before. .023" was removed from the original .045" and this now resulted in a nice smooth 10 in/lb preload. That's .023" of in/out slop that it used to have and that is reason #2 for the noise and breakage.
Love how Toyota auto dabs the clear grease on.
Seal is carefully tapped down in a level fashion until it is recessed about .170" all the way around.
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Flange seal surface has been wet sanded with #1500.
150 ft/lb on the small pinion nut. These small nuts will strip out at about 200 ft/lb.
Lots of gear oil was on both bearings and a nice, smooth 10 in/lb of measured preload.
Nut is not threaded as deep as before. Ding!! and this end is complete.
Now fine tuning the backlash and bearing preload.
Tab locks are on and tightened to 10 ft/lb.
Date coded.
It doesn't get too much better than this.
Brent now uses Amsoil Severe Gear 75W-90 for best possible lubrication and reduced temps..
Notes taken during the setup.