CPO 23 Tundra 1794 on its 4th rear differential

Hello to all,

I am new to the forum, and tried to research if a thread was open already on this or not. I came up empty (Hopefully not user error). I purchased a CPO 23 Tundra 1794 (Non Max) a day after Christmas 23'. I love the truck but it had a crazy noise from 70-80mph and 40-45mph. I drove it this way for about 2k miles before I finally decided to become a google detective and see what was going on. It wasnt wind noise, however it was directly tied to the throttle and only under acceleration. I found a random Youtube video of someone who claimed it to be the rear diff. I took it Toyota of Lakeland and low and behold..... Metal shavings in the diff. They replaced it, then tested it. While it was in the shop, it ATE another diff so they installed a 3rd. I was told it was good to go and picked up my truck. We took the kids to Disney and sure as S*** the moment we hit 75MPH the dreaded Howl came back. Its very prevelant with the rear window down. I just dropped it today again at Toyota. My question is, how long will they continue to do this if it keeps eating rear diffs? Could it be a driveshaft issue? Anyone having a similar issue to me? Im at a loss on what to do currently. I took a bath trading in a 2023 Escalade we paid over sticker for, and truly planned on keeping this truck awhile.

 

Not a lot of things interface the differential, so if we assume at least one diff was good and still went to shit, that would imply either the driveshaft or the axle shafts (and perhaps by extension the axle housing itself) are somehow causing issues.

It would seem more likely to be a driveshaft issue, but even that sounds weird to me to cause that level of issue but it is extraneous circumstances.... Being a 3rd member I don't know what else could cause the issue, ASSUMING the whole 3rd is being replaced.

 

I wonder if they didn’t get all the shavings cleaned out from the first failure. Did they replace the entire assembly including axle housing, axles and diff or just replace the differential assembly and reused the original housing and axles?

 

When you say it's eating diffs, do you know what's happening to it? Does it have the factory e-locker or open diff? Is it eating bearings, spider gears, ring, pinion? Does the howling sound only hit at those two speeds or does it gradually get louder and is loudest at those speeds.
If they've replace the diff twice and and the third was damaged while still in the shop it's probably not the diff. I'd start with the driveshaft, make sure it's balanced correctly and in phase. If they're on their third 4th diff I'd hope while the diff is out they checked the axles and bearings. I doubt it would be the housing, if it was bent sliding in the axles would be difficult depending on how bent it was. Again, another simple check to perform while the diff is out.
Just for craps and giggles I'd ask them to check the transfer case for damage or metal shavings, do a drain and fill. If it's an out of phase or unbalanced driveshaft that could also affect the transfer.

 

Theres a certain talent that may be needed to repair the diff in a rearend. As an example, they have to be adjusted just right (lash)
Do the local dealer techs know how to repair it right? Maybe. Be nice if they farmed it out to a specialty shop that does this on a daily.

Can the axle shafts be bad? Geez that wouldnt be a normal thing.

 

I feel like an improperly balanced drive shaft would be felt at those speeds. Is there any vibration at all?

 

Lord have mercy...4 differential assemblies?

They need to be checking pinion angle horizontally and vertically. Something is not aligned right.

If these are remanufactured differentials then that is a whole other mess...easy to get a number of things wrong with these.

 

I recommend getting Yota Corporate involved at this point. I'm fairly certain they'd be quite interested in this situation. A field engineer needs to oversee what going on. 4 diffs is nutz.

 

this…had a friend that would do a lot of
gear swaps on mustangs…sometimes they would go right in and be perfect, other times he would be cursing cause he would have to re do it a couple times trying to get the lash and shims or whatever just right.

 

Did the CarFax indicate work before you bought it? You say CPO but was it titled/owned before?

Lemons happen. Always be aware of the newer vehicle traded in with low miles. There are a lot of reasons a new vehicle gets traded in. Many of them are bad

 

Are they replacing the whole third member or are they rebuilding it with new parts? I'm sorry but rebuilding third members is a very tedious process that takes years of practice to get it right. I can't see a tech spending the time to check backlash, preload, wear pattern and everything else involved in rebuilding these things and getting it correct.

 

Welcome to Tundras.com and congrats on new rig !

 

Yikes, hopefully that’s the end of the problems for you, that would make me pretty agitated

 

Sorry for the late reply, I hope everyone had an epic 4th. To answer the questions it was a Clean Carfax, no work performed CPO vehicle bought from a dealer with 8k miles. They are indeed sending out an engineer from Toyota. Corporate is involved. My service department is beyond frustrated, which I can understand but none of this is my fault. They released the truck to me with a statement they dont know what to do. Before releasing it they tried to tell me that the tech, shop foreman and manager all drove it and couldnt recreate the issue. I offered to come out and drive with them. They pulled up a like model 1794 and we drove it for 30 miles. No whine. Then we drove mine, and I was able to recreate with 100% consistency the diff whine, only under throttle at the speeds indidcated (40-45 and 70-85mp) They were in awe to say the least. I did attempt to trade out, but the numbers given are HORRIBLE. Even the manager couldnt believe taking a $15k hit on a 6 month old Tundra CPO. I am really hoping Toyota gets it together on these trucks. I love it but its been in the shop every month since owning, and thats with me "Overlooking" some other minor complaints in order to Triage my current situation.

 

Well boys, Toyota has stated no repair and there isn't an issue. This is AFTER driving with the manager and hearing the noise. I am genuinely at a loss that Toyota would do this to consumers. I will be posting Videos of the issue to youtube, Tik Tok and every other social media outlet available. I am contemplating posting videos of interactions with Toyota, but I dont know the legalities of that and I will blast this company until the end of my days. It is unreal how they have left their customers out to dry. I want to upload the video to this site, so you all can hear what I experience DAILY. Is there size limit to videos?

 

That sucks and sorry you have to deal with that.

I wonder how they break-in rear diff’s after a vehicle is built?

I know when the rear differential in our 1st gen Tacoma started to howl at 245k miles I slapped in a rebuilt third member from East Coast Gear Supply. The third member came with strict break-in procedures for the first 500 miles. Step 1 was “On initial run, drive lightly for 15 to 20 minutes then stop to allow differential to cool completely for 20 to 25 minutes.” After 15 minutes of light driving I could not believe how hot the rear diff was.

https://eastcoastgearsupply.com/files/PDF Files/break-in-procedure.pdf

 

I'd ask the manager to take it as a trade on something else...

 

That sucks man, can’t understand how they can say that if it’s only on yours and not a new truck…can you get Toyota corporate involved or try a different dealer? Maybe car care nut or Scotty Kilmer will fix it for a YouTube video

 

Likely they swapped out third member (do you know) and didn't rebuild what you had. If thats the case then your housing would be the issue if its eating the thirds still. A bent housing would do that.

FWIW, Carfax doesn't mean jack. Its only as good as the info provided to it and a LOT of things never get reported.

 

They were all new. What sucks is Toyota Corporate stated that they cant do anything. They are saying the dealership noted it was "Rear Window Noise" and not the diff, even though the the manager heard the noise. The customer service manager test drove both trucks and heard the noise with the window up. Then, asked if its louder with the rear window down, so I rolled it down and it was much louder. It is only under throttle / load and only under certain ranges. I am at a loss. Sorry for the earlier rant but my blood was boiling. I came out of a 23 Escalade Sport Platinum for this truck thinking It was quality. I love every Lexus we own and my Tacoma is a beast. This "NEW" Tundra is a pile of rattles and constant issues, which to be fair, happens with new vehicle launches. I just never thought id live to see the day Toyota didnt care. They have always made things right. I am just defeated. I have no words.

 

Sell it and move on. Life’s short.

 

I attempted that, they are expecting me to eat a $15k loss after 6 months. Paid $65k beginning of the year and now they are offering $50k for trade. These new tundras have plummeted in value. Honestly im just weighing my options. Something is wrong, and will present itself in the future as a failure of some sort. Im CPO for 7 years 100k so they will end up fixing it. Just annoying and frustrating.

 

I've got the same whine at 45 and 78mph. Dealer replaced the rear diff with brand new one and same thing is happening...

They are either keep installing bad differentials for everyone or this whine issue is caused by something else...

Would an independent shop be able to diagnose exactly what's causing this whine?

 

What is CPO?

 

Certified Pre Owned

 

Thanks very much!

 

If the dropout was swapped for a new one then the dropout is NOT the issue.
Good chance the housings are bent or theres an alignment issue between the axle shaft bearing mount and the dropout. An alignment bar would tell you. Bent axle shaft too

Theres only a few things it can be, personally given the intermittent sound I'd look at the axle bearings first. Sadly, no affordable way to swap out new ones to find out.

 

Sometimes the rear diff noise is hard to isolate from the cab. I changed both rear wheel bearings on our Tacoma before I decided to attach a GoPro (with a magnet) to the diff.

 

After some thought, I'd look at the axle shafts first to see if they'er bent. You're hearing the harmonics that show up in two distinct speeds, the sound is probably always there, you just can't hear it.