Old 4Runner new to me, a story

After the debacle over the weekend, I returned to searching Craigslist, eBay, car-part and others for deals on 4.88 third members. Sunday evening, a new listing on eBay popped up that was a pretty good deal so I clicked the Buy It Now button to get it sent my way. These factory third members are all from 92-95 V6 trucks and 4Runners, so that means they all have the stronger and more desirable 4-pinion carrier versus the 2-pinion carriers found in the 4 cylinder trucks. The downside is the housing is only able to accept the special (read: expensive) OEM ring/pinion should it ever chunk the gearset.

But now the plan moving forward offers multiple options. I could put a lunchbox in the V6 carrier, install that in the rear axle, then regear the third just removed and install in the front.  Or I could just buy another 4.88 V6 third member and put that in the front, leaving two old 4.10 4cyl thirds to sell off. A third option would be to put the V6 third in the front axle, and then put a Supra LSD in the 4cyl third, regear it, and put that in the rear. That option would give the truck the best street manners but would also be the most expensive way to go. It would also eliminate the "weakness" of the 2-pinion carrier. Either regearing scenario would be the first time I'll ever have done that, so I would be just a bit leery of my ability to set it up exactly right, especially in the rear where it would see continuous use.

Today it was time to tackle the parking brakes. Surprisingly to me, the cables were actually completely free and not frozen with rust like is usually seen in the northeast. The bell cranks, however, were both well seized. With a little bit of elbow grease, and a bunch of PB Blaster, the right side bell crank freed up enough to be serviceable. The left hand side did not take so kindly to the abuse, and actually broke the housing!

Fortunately, there are aftermarket kits for the external parking brake parts for Toyotas. Unfortunately, none are designed specifically for the 85 and older axles, which use a smaller 10" drum than the 86's 11" setup. Taking a chance, I picked up Dorman 9240-753 which is specced for 3rd 4Runners, mostly because it was the only option available in town!

Turns out that the parts kit is an exact fit, other than the bell crank itself. Cleaning and painting it for reuse, the housing installation was a matter of taking out the brake shoes to gain access to the mounting bolts, putting the new parts in place and the liberal application of lube to help prevent further issues. The kit includes nylon washers to go between the housing and bell crank to reduce friction as well.

I also replaced the return springs with the ones from the kit, as they are shorter and stiffer resulting in a more positive return action.

Because I was able to free up the right hand side well enough, I didn't bother to tear apart the brakes to replace the housing. If it gets sticky/seized again, then I can tackle it.

Final step was to set the correct slack in the cable itself. The cable at the end of the linkage (exiting frame right) goes to the handle in the cab itself, while the long threaded adjuster is part of the cable running to the rear axle. Holding the ferrule on the end of the cable to keep it from spinning, the adjuster nuts were set so there was the slightest bit of slack in the cables so the parking brake wasn't riding on.

The project this week was the first half of regearing the differentials. Because of the bigger tires, the already woefully adequate 22RE was struggling to push the 4Runner around. The stock 4.10:1 gear ratio in the diffs is perfect for 28" tall tires; moving to 33"s means 4.88:1 gears are going in.

Fortunately, Toyota already did that for me, as 1992-1995ish 4Runners with the auto trans and 31"s came from the factory with 4.88 gears. I ordered one of those third members from eBay, with the plan being to remove the old third member from the rear, install this new one, then regear the old third to put in the front. Phase one was completed today.

After jacking up the rear axle and removing the wheels, the fluid fill and drain plugs were removed. On each side, the four nuts securing the bearing were removed, followed by disconnecting the parking brake cable (single pin) and the brake line to wheel cylinder. This allowed each axle to be pulled out of the housing, where it could be safely set aside. Four bolts hold the driveshaft to the differential, so these were removed and the driveshaft secured out of the way with a ratchet strap. Finally, the ten nuts holding the third member to the axle housing were removed, and the third was carefully rocked away from its former home.

The new third member had been prepped earlier, all its old gasket material removed and cleaned up with a scraper and brake clean. But, rather than just leaving well enough alone, the contents of a small box were installed.

These couplers replace the spider gears, while the four pins and springs provide preload and alignment

After match-marking the bearing caps and adjusters, the carrier was removed, then split by removing the 8 bolts holding the case halves together. The side gear is pushed out, the thrust washer removed, and the side gear reinstalled. The ring half has a drilled match-mark from the factory (upper left)...

... that matches the pinion half (upper right). Those are the 8 bolts that held them together. The spider cross is removed, and its spiders are set aside. Again, the thrust washer was removed from behind the side gear.

Here are the parts thus far removed. Both carrier bearing races, adjusters and caps, along with the lock tabs and bolts are to be reused. The thrust washers and spider gears will not be going back.

Instead, one of the couplers is placed on the side gear, with a spacer ring inside, followed by two of the pins with springs inside, and the spider cross. The slots in the couplers are bigger than the cross and ramped to cause the cross to force the couplers into the side gears when applying power.

The other two lock pins and springs were set on the already installed coupler so the other coupler could be settled on top, making sure the pins became inserted in their respective holes. The spacer ring was put in place, and the other side gear set on its coupler. Not shown is the final reassembly: the other case half was set in place, aligning the drilled match-mark, and reinstalling and torquing the eight case bolts to spec. The carrier was then set into the third member, with the races, adjusters and caps installed onto their original locations. By aligning the match-marks on the adjusters, backlash and bearing preload were returned to their factory settings. Backlash was checked nevertheless, and maintained its original 0.006" spec.

Installation, as they say, is the reverse of removal. Rather than use a gasket, Right Stuff brand RTV was applied to the sealing surface of the axle housing, and the third member was slid into the place. I snugged the nuts holding it in place immediately, but did not torque them to spec until waiting about 10 minutes to allow the RTV to set up a bit. Doing it that was has proven successful in the past, preventing any future leaks. The driveshaft and axles were reinstalled, the brakes bled, and wheels installed.

On to the test drive!

(nope, mowed the lawn instead)