92 4runner V6 A/T 352000 km. I'm getting a bad whine from my rear diff. Thus, I'm planning on replacing/repairing. Based on this 4runner set up, and the G144 axle code on the door pillar, I believe that it is 4.88 gear ratio. After having found Erik's write up (awesome btw) he makes clear that this factory 4.88 set-up is unique. If I cannot source a used 4.88 3rd member (or at least one that is affordable), will my differential housing(s) accept a 4.30 set up (whereby I would replace both Front and Rear) from a 94 V6?

My understanding in this write up http://home.4x4wire.com/erik/diffs/#v6/turbo is a bit murky. If I have to replace both, so be it. However, when I read "Housing offsets pinion towards ring gear, allowing ring gear to be thinner", I'm not entirely sure I can swap in a different gear ratio, even if I do both front and back. Any feedback would be great.

 

if you are getting the complete thirds the 4.30 rear 3rd will be a direct replacement.
you can't use 4.30 gears on the factory 4.88 carrier from what I understand

 

They would be complete 3rds, not just the gears. I had thought the maybe the differential housing was different. Thanks for the reply.

 

What dropzone says and what you understand from Erik's page are true, that factory 4.88 ring gear is thinner and the hole for the pinion is offset to account for the thinner gear. You might be getting ahead of yourself though,maybe there's nothing wrong with your ring and pinion, maybe you just need to inspect\replace bearings, maybe pinion nut has come loose or the crush sleeve is fatigued after all these years...are you just trying to avoid any downtime by finding another diff? Lot of avenues to take here. Without a press and some unique tools you can still do a few things. On the truck without removing the diff, you can see if the pinion nut is still staked and see if there is any in\out play in the pinion. You could pull the diff and look at the gears, even check the pattern, and try to feel for "crunchiness" in the bearings. If you feel brave and the bearings seem ok, you can mark the adjuster wheels and count the threads showing and take the whole carrier out and try to check\set the pinion pre-load by re-crushing the sleeve a bit (well I guess you need the in-lb torque wrench for checking the preload), then put it all back where it was. You can buy a dial indicator at Harbor Freight for pretty cheap and then you can set the backlash to spec. Read gearinstalls.com for more than you ever wanted to know about gear setup.

 

Hey cory. Thanks for the detailed reply. Yeah, I thought about a few options that your mentioned but don't have the experience to know about the cruchiness of bearings, or using a dial indicator. Essentially, the rear diff whines when I'm accelerating (or under load) and is quiet when I'm coasting. Everything I've read suggested the ring and pinon. In terms of easiness, I was just hoping to pop in a used 4.88. However, they are a little harder to come by , thus, my idea about replacing both front and rear at the same time with a different gear ratio. I will look into some of your suggested ideas though. Thanks.

 

Keep in mind that going from 4.88 to 4.30 is a pretty big step, and it will definitely change how your truck drives. It won't feel nearly as responsive in the higher gears, and will downshift a lot more on gentle grades. On the other hand, it will cruise more quietly on the highway.

A possible compromise is to look for 4.56 gears. These were stock in the 91-95 SR5 trucks with manual trannys and 31 inch tires. I would think they would be almost as common as the 4.30 gears, and wouldn't be quite as drastic a change in gear ratios and driveability.