It was this spot on Riffel Canyon that claimed my front ring and pinion.
When I got Tuffy home, I dropped the driveshaft and pulled the wheels, hubs, calipers, rotors, spindles and axles to get the front diff housing out. Once I had it out, I found the damage.
I broke a few teeth off the ring gear at Riffel. I believe it happened due to ring gear deflection. This happens when the carrier bearing preload is too loose.
The last time out I used an affordable ring and pinion from Genuine. This time I want to use a dependable set known for their quality and ability to take the abuse. Even though the damage could probably have been avoided by checking my carrier bearing pre load, and making the Genuine's last, I'm not taking any chances this time.
With the diff housing disassembled, the next step is to rebuild it! I built both front and rear gears the first time, so at least it isn't too intimidating.
I probably could have re-used the old bearings, they were only four years old, but for $100 or so, a Master Kit is cheap insurance. So I tapped out the old bearing races and, using a soft steel punch, tapped in the new ones.
To set the pinion depth, I started out with the stock 4 cyl. shim of .231". I got a suggestion of .076-.080 for setting up Precision's. Even though these gears came packaged in a Precision box, there wasn't the PG stamp on the parts, so I used the stock specs for setting up 4 cyl. gears as a starting point.
Naturally, I'm using a solid collar to set these up. I'm starting with a .066" shim thickness. I'm shooting for about 6-10 inch pounds of pinion bearing pre-load once they are in the diff housing.
Once the pinion gear was in the housing, I could get the ring gear bolted to the Detroit locker.
70 ft. lb. on the ring gear bolts. New ones come with the master kit.
Oh yeah, I used thread locker.
Before torqueing the carrier bearing caps, I set the carrier bearing preload to 150 ft.lb., checking to make sure the backlash didn't change.
I initially set the backlash at .007"
The first attempt showed the pinion gear was too tall with that .231" shim, so I tried again. This time I assumed these were Precision Gears since they came packaged in a Precision Gear box, even though they didn't have the familiar PG stamp on them, and tried a .077" shim thickness.
Now that's more like it. It looks good. I came close with .077, but I finally settled on a .074 at the pinion and .062 at the collar. This gave me a good pattern and decent pinion bearing preload of 6 inch pounds.
Coast side. Normally, I'd try to lower the pinion gear a little more to center the pattern, but since Tuffy's used primarily for extreme rock crawling, the pattern, which would be good for competition, should be good for our application.
After satisfied with the setting I eventually achieved, I set the bearings ( a little trick from Zuk), torqued the carrier bearing caps and fastened the retainers.
A new seal came with the master kit, but I went with authentic Toyota for this build. Only the best for Tuffy!
A little RTV for good luck,
some thread locker for the nut, torque it to 200 ft.lb. and I'm ready to bolt it back up.
I have the Toyota gear install guru, Zuk, to thank for all his time and expertise. I bugged him through out the process. He's very knowledgeable, has untold hours doing this very thing, and very graciously shared his wisdom.
Being able to get advice, tips and tricks from someone like him, while doing this build, really alleviated any doubts and fear I would have otherwise had to deal with. I was proud to get his approval of my efforts once finished. Thanks Zuk!
If I didn't enjoy wrenching on my junk as much as I do, or didn't have the time to do it, I'd trust him with my gear set-up.
You should check out his site... Gear Installs