Hey guys! New here. Just wanted to ask some questions and hope someone can respond to them.

Story: I got a 1998 T4R SR5 4x4. Had to replace my trans about a year and a half ago. It had a crack in it. No idea how it happened. Mechanic didn't know either. Then about 6 months after the the trans was replaced, the 4runner started shaking a lot more than it used too while driving. Then I noticed all this thick black dirt all over the back windshield. Took it back to the mechanic a while after and had him look into it. Turns out that I had a leak in the diff and that was the gear oil splattering on my back end. He replaced a gasket I believe and cleaned the breather but it started leaking again. Mechanic said to replace the rear diff cause I rode it too long without oil and to also replace the rear axle. He said the vibration from all the shaking is what probably caused the diff to leak again and the trans to crack previously. Now the muffler broke too. I told him I'd get back to him once I decided what I wanted to do.


I'm looking to get it fixed as I don't have the money to buy a new car but I can spend up to $3k to get this fixed. My questions are...

1. What's the average cost of a new rear axle assembly with diff and all gears included?

2. I found some used but I'm not savy enough to know 100% it's exactly everything I need or what I should be typing in the search.

3. Should I go to the dealer to get this done?


Thanks in advance!!!

So the black dirt on the back window is from a leaking diff? Was it a bad axle seal or an actual hole rotted through the housing? (neither would kick sh*t allover the back window IMO.).

The shaking is probably a bad u-joint if I had to guess.

Where do you live? I'm sure one of us could take a look and help you out.

I live in Jersey. The black dirt was actually the oil getting kicked up while I was driving. I had no clue it was leaking and for 6 months or so I kept driving it. The mechanic said the seal blew and he replaced it, but then it happened again. He said that since I drove it for so long without oil I screwed up the gears and that the whole rear axle would need replacing since the damage carried over.

The u-joint thing makes sense. Could have been a bad joint, then the shaking cause the crack in the trans, then the seal to go in the diff. then driving with no gear oil damaged the gears in the diff and axle? Just a guess. =)

Edit: Forgot to add the exhaust pipe to the muffler broke off to due to the shaking.

I'm not the world's smartest T4R owner but your mechanics statements sound fishy to me. I can't imagine the differential running at all without oil. I think it would lock up and come to a catastrophic halt. See here for an example of what happens when there is no lubrication in the differential Toyota gear install I can imagine it leaking but I can't see how the gear oil could possibly get to the rear hatch window. The rear axle seals are near the hub and are inside the wheel well. The differential is mounted in the middle of the car and tucked in by a few feet forward of the bumper.

1) The rear differential is contained in bell housing called the third member. The axle housing runs from wheel to wheel. The third member bolts to the drive axle on one end and the axle housing on the other end. I've seen complete rear axles with differentials included for $500 in salvage yards. In fact, there's one near cleveland with an electronic locker on it too when I looked a few months ago. Found it on the Ohio TTORA site. You might be able to buy just a third member with 4.10 gears in it off this site for about $100 if there is one available. You'd pay another $75 to get it shipped since they are so fricking heavy. Finally, you could get a built 3rd member with the gears you want from East Coast Gear Supply. That would be about $500 shipped or so.

2) you should type in 3rd member or rear diff or rear differential or 4.10 gears. You do need to know what gear ration you have otherwise you'll have major issue if it is different then the front. My write up for the aussie locker install will help you understand what you would have to do in order to do the work yourself. You could do it with another guy in 10 hours in a garage if you had the tools. I would guess you could replace the rear third member in 3 hours by yourself if you had done it once before. It's actually pretty easy. Aussie Locker Rear Differential Installation Write-up

3) I wouldn't take this one to a dealer. There's nothing exotic about the repair that any shop couldn't do. You'd be looking at $1000-$1500 I would guess.

I guess I should have explained how the oil got onto the rear windshield. It's a slow-ish leak (takes about a week or two to empty out), coming from I guess where you bolt the third member to the drive axle (to the left of the nut you take out to put in the oil). I was driving the car and while it was leaking the wind/air/vacuum would carry the drops of oil to the back of the car and then up onto the back end. It's not just the windshield, it's the whole back that was covered in it. I'll try and take some pics to post later. The car is FWD with a shifter for 4WD/2WD L/2WD H/Neutral. I tried putting it in 4WD once and it made the shaking worse and now I can hear clinging sounds while driving. As long as I keep it in FWD it runs. Not great but it gets me to work and back as long as I stay under 50mph.

The axle code is A03A 4.10 locked w/abs.

Thanks for the links, I'm looking at them now!

Do you have a rear locker on your differential? There would be a little button on the left side of the dash panel next to the steering wheel that says "RR Diff". That would affect how you approach this.

I'm not sure why engaging 4WD would make the shaking worse. The power always goes to the rear wheels when you are moving and engaging 4WD allows power to go the front wheels too.

The repair would be easy if all you need to do is replace the third member and axles. I'd be concerned that you would be paying the mechanic for that but still having issues because the leak is due to an issue on the axle housing surface that mates with the third member. You'd still have the leak if that was the case.

Everything that Gannon said. If you'd run the diff dry, the best that would have happened is you'd overheat it and it'd lock up. More likely, IMO, it would have grenaded. I doubt very much you need new gears, let alone a new axle. You DO need a new mechanic, though.

If you're at all handy with a wrench, I'd pull the third yourself. Make sure there's no chunks missing from the ring and pinion, maybe take it to a driveline shop and have them make sure the gears are still in tolerance. Stick a straight edge in various places along the axle housing and third mating surfaces, make sure they aren't warped. Visually inspect for gouges. When you put it back on, use Toyota gasket maker instead of one of those crappy paper gaskets - the gasket maker is more tolerant of surface imperfections and and you're much more likely to get a good seal. If the third checks out and the axle splines are in good shape, then there's nothing wrong with your diff other than the leak, and gasket maker should handle that.

I don't think your truck is front wheel drive, by the way, not unless the transfer case has been heavily modified. The vibration when you put it in four wheel drive could be an unbalanced driveshaft. I'd chase it just like any other vibe, though. Start by balancing the tires and getting an alignment, and go from there.

where are you in new jersey? actually it doesn't matter where you are in jersey. i'm right in the middle of the state. you need to come see me.

No "RR Diff" button. The shaking / noise from muffler got worse right after when I took it out of 4WD.


Sorry, I thought 2wd was the same as fwd. There is a shop around here that a mechanic friend of mine (I asked him to look at my truck but he's really got no time as he travels a lot and I only see him once a month now) recommended. I can see what this guys tells me. Oh and I chased the shaking a lot. Did an alignment, balanced tires, got shocks checked, all that stuff. I'll have some one look at the u-joint next time.

What town!?

on the coast in between asbury park and point pleasant.