Rear Diff Question (1 Viewer)

[yetiwf]

I started having a vibration in the LC a few weeks ago. you can feel it in the floor, seat and steering wheel. So I replaced the ujoints with toyota parts then had the shafts balanced. problem seems to have gotten worse. I decided to take it to the dealer for a diagnosis. after 3 days, they said that the vibration is due to rust in the rear diff and the whole thing needs to be replaced. couple of questions. how can rust in the rear diff cause the whole drivetrain to vibrate? does this make sense to folks smarter than myself? also, they are not quoting replacing the gears, but replacing the whole housing for almost 5k. can the gears be replaced? can I add an aftermarket diff locker instead? any pointers would be appreciated. I just really don't want to drop 5k on a rear diff. thanks

2000 LC without rear factory locker

 

[saucebox]

Diffs for some reason are regarded as super scary, or super difficult...for some reason. They're really not that bad to DIY, and you could absolutely add an aftermarket locker while you're in there. Gears can absolutely be replaced, people re-gear all the time. I'd guess you're in for a minumum of that, along with the kit that replaces all of the bearings and seals. $2-300 in tools and you're equipped to DIY.

IIRC there's an LC-specific JY in Austin...@arcteryx's place, I think. You can straight-swap any rear third member from 1998-2002 if you're not into the DIY aspects of gear setup, or add a locker while it's out and available (but you're definitely deep into the DIY at that point).

I'm pretty sure Cruiser Outfitters can help as well in getting the right parts and getting them set up so it's just plug and play for you, but you'd have to call them to see what their parts availability looks like right now. Either of those options should be laughably under $5K, even with upgrades like a locker.

 

[SteveH]

I would like to see the dealer's photos of 'rust in the rear axle' - which would require them to pull the 3rd member to properly see.

I bought a junkyard locker axle for $400, swapped it in, and bought a Trail Gear $200 wiring kit and now have a rear locker and a rear axle with only 200K miles on it, versus 315K. Swapping the axle wasn't a 1 banana job, but with a few jacks, wasn't too hard.

If you're averse to doing a full axle swap, a shop can do this (not the dealer) for reasonable money.

 

[yetiwf]

thanks for the replies. would this diff issue cause a vibration throughout the whole driveline?

 

[TexLexican]

thanks for the replies. would this diff issue cause a vibration throughout the whole driveline?

I had similar vibrations in my 4Runner. Went underneath and noticed both ends at the seals and the gasket around the pumpkin are leaking. I refilled whatever fluid was lost and the vibrations stopped. Next time I refill I’ll use AT-205 reseal and see what happens longer term.

 

[SteveH]

Generally, diffs make a lot of noise before they cause massive vibration, unless the failure is catastrophic.

 

[Mike NXP]

I started having a vibration in the LC a few weeks ago. you can feel it in the floor, seat and steering wheel. So I replaced the ujoints with toyota parts then had the shafts balanced. problem seems to have gotten worse. I decided to take it to the dealer for a diagnosis. after 3 days, they said that the vibration is due to rust in the rear diff and the whole thing needs to be replaced. couple of questions. how can rust in the rear diff cause the whole drivetrain to vibrate? does this make sense to folks smarter than myself? also, they are not quoting replacing the gears, but replacing the whole housing for almost 5k. can the gears be replaced? can I add an aftermarket diff locker instead? any pointers would be appreciated. I just really don't want to drop 5k on a rear diff. thanks

2000 LC without rear factory locker

This is pretty absurd, and I'm not just some anti-dealer guy. I bring my rig to Toyota alot.

Tell them to prove what they are saying OR get them to sign off on if you replace the rear diff it would 100% fix the problem. I suspect they can't do either of those.

Is it even possible to see inside our rear diff? It's not like you can just pop the case off like on some old s***ty pickup trucks. Maybe they scoped from the fill hole?

I'm not too smart but how could gears soaked in oil rust? Has the vehicle sat for a decade? Most vibrations should first lead you to tires / steering / suspension parts, not driveline. There is also virtually no reports of these rear diffs failing / rusting / causing vibrations without different symptoms involved. I would also think you'd feel it in the wheel and not just some floor vibrations. I'd love to get some more info out of that dealer as to how they diagnosed that, did they rotate tires, test drive, anything? Or did you go in there telling them you just swapped u-joints and have a driveline problem, that is there IN to just replace the next most expensive part that relates to your original complaint.

Take it somewhere else and just say, I have vibrations felt in floorboard when driving and let them figure it out. Offer to pay them for half hour / hour diagnosis time.

 

[yetiwf]

I told them everything I did but they put about 20 miles on it. I am not sure how they saw the rust. I drained the fluid when I got it home and it was just as clean as when I changed it 6 month ago. seems suspicious to me. I did ask if I did this would they guarantee it. the dealer said they cannot be sure there isn't other things wrong with it. so that was their "out". I am going to take it to another shop for a second opinion. although, the price they quoted me for the carrier was over 2k. found a new toyota carrier online for 835. I think I will keep digging before I proceed

 

[Mike NXP]

I told them everything I did but they put about 20 miles on it. I am not sure how they saw the rust. I drained the fluid when I got it home and it was just as clean as when I changed it 6 month ago. seems suspicious to me. I did ask if I did this would they guarantee it. the dealer said they cannot be sure there isn't other things wrong with it. so that was their "out". I am going to take it to another shop for a second opinion. although, the price they quoted me for the carrier was over 2k. found a new toyota carrier online for 835. I think I will keep digging before I proceed

Good call. You've got time to ask around and check to see if anyone else has had this issue on the forums.

So what, at all speeds you feel some vibrations in then floor? Do you feel it in the steering wheel? Does it ever go away ? What condition are your tires in ? When did you start feeling the issue ?

These are then questions that help narrow it down that the dealership doesn't have time to ask.

 

[yetiwf]

Good call. You've got time to ask around and check to see if anyone else has had this issue on the forums.

So what, at all speeds you feel some vibrations in then floor? Do you feel it in the steering wheel? Does it ever go away ? What condition are your tires in ? When did you start feeling the issue ?

These are then questions that help narrow it down that the dealership doesn't have time to ask.

Tires are new 4k miles on them. You can start feeling it around 45 mph and it gets worse the faster you drive. If you let off the pedal, it does not go away. You can feel in the floor, wheel and seat. At 60 it starts making all the plastic dash parts rattle. You can also hear the vibration at higher speeds. Not sure if that makes sense

 

[Mike NXP]

Tires are new 4k miles on them. You can start feeling it around 45 mph and it gets worse the faster you drive. If you let off the pedal, it does not go away. You can feel in the floor, wheel and seat. At 60 it starts making all the plastic dash parts rattle. You can also hear the vibration at higher speeds. Not sure if that makes sense

Trying to eliminate the simple stuff first like tire balance and tredwear. So the vibration wasn't there after you got the new tires , just recently.

Dang it does sound like a pretty decent shake if you're feeling it all over.

Will need someone with more experience or better mechanic to help sort this one out. But I'd think there are still other possible suspects before condemning the differential. I assume Toyota would have shaken down the front end to make sure everything is tight. Second opinion from another mechanic would be nice

 

[kevgentile]

Until you can find a good shop I'd post up in the clubhouse to see if you can meet up with another member in your area that might have some quality experience with the platform. Another set of eyes and hands could be of great value before spending money on questionable diag.

Need to get each corner unloaded and check over all the suspension links and pick up points. Make sure a link or bushing isn't loose or failing. Our shop car has the worst vibration in the front end due to a bad trust arm.

I would expect a diff vibration would be accompanied by noise too, especially if internal.

 

[SteveH]

Get the whole truck in the air on a lift, several inches off the ground, and start the engine and put it in gear. Any noises will be very easy to spot. I had a Toyota dealer do this with my 4Runner to find bad rear wheel bearings. You can just let the truck idle in 1st gear so it doesn't run crazy fast on the lift.

 

[Patassa]

I started having a vibration in the LC a few weeks ago. you can feel it in the floor, seat and steering wheel. So I replaced the ujoints with toyota parts then had the shafts balanced. problem seems to have gotten worse. I decided to take it to the dealer for a diagnosis. after 3 days, they said that the vibration is due to rust in the rear diff and the whole thing needs to be replaced. couple of questions. how can rust in the rear diff cause the whole drivetrain to vibrate? does this make sense to folks smarter than myself? also, they are not quoting replacing the gears, but replacing the whole housing for almost 5k. can the gears be replaced? can I add an aftermarket diff locker instead? any pointers would be appreciated. I just really don't want to drop 5k on a rear diff. thanks

2000 LC without rear factory locker

First time I've ever heard of rust in a rear diff. Seems like if it were run dry, you'd have much worse problems than that first. Color me skeptical of that diagnosis

 

[Fairgame]

Check the output on the gearbox to see if there is any play but I am betting you need to balance your tires

 

[OwnerCS]

I'm a stickler about pinion angle from owning a Tacoma. I remember setting the pinion angle on my 100 a couple of years back. It was smooth as glass after that. That might be something to check.

 

[Bomar]

I hate to ask but what type of tires.

You also could have 2 bad tires. Have you rotated tires just to see?

 

[yetiwf]

So I’m at discount tire now. Figured I’d try the balance again. They are going to check out the tires again. I’ll let y’all know.

Tires are cooper discoverer or something. Just an AT tire with about 5k miles on them. If this doesn’t fix I’m going to fire sale it. I just ordered front and rear bumpers from blue lake off-road. So I may just lay the seats down, put parts in it and let her go.

 

[yetiwf]

So I’m at discount tire now. Figured I’d try the balance again. They are going to check out the tires again. I’ll let y’all know.

Tires are cooper discoverer or something. Just an AT tire with about 5k miles on them. If this doesn’t fix I’m going to fire sale it. I just ordered front and rear bumpers from blue lake off-road. So I may just lay the seats down, put parts in it and let her go.

 

[yetiwf]

Well, that did nothing. Still the same. I appreciate your help with everything. I’m just going to let her go. Thanks y’all