Rear Diff Cover Replacement

Hey all - so I was planning a spring project to replace/reweld (by a pro) a new rear diff cover, replace bearings, seals, drum backing plates, maybe even new leafs. I'm a 2nd owner of a 2002 4WD Access Cab in NE PA and mine is actually not leaking. It is quite rusty and scaley, but has never been wet. I want to replace my fluid, but I'm afradi to wrench on the filler plug until prepared to replace it - it just looks like I could possibly crack it open and cause a leak.

I've read all the posts about POR15, welding, and new housings but the thing that has me puzzled is the actual replacement cover to buy. For some reason, the

$63 Dorman 926-958 Rear Differential Cover Compatible with Select Toyota Models (OE FIX)

Dorman 926-958 which is the only one listed for the 1st gen Tundra claims it is not a fit for the 4WD rear. I even contacted Dorman and they confirmed. I still think they're wrong. Then of course there's the Barnes B4W0008K.

Can anyone confirm if these are both a proper fit for the 2002 4WD SR5 w/ LSD Access Cab?

Thanks in advance guys!

 

If going to do bearings, seals, and backing plates you may just consider a full housing replacement. By the time you do all that work to this one and have someone weld it, you may have just been able to buy a replacement housing for not much more.

 

Correct me if I'm wrong, but a new housing replacement is a blank shell at $1200 new with no other parts, and a used one (if it even came with axles) would probably need to have the axle bearings replaced anyway so really not cost similar. I can get the cover for $60 and have access to a free professional welder after I cut off the cover. I plan to do this with the housing removed.

 

There have been a few guys that have used the Dorman cover, but without searching for the posts, I can't confirm if those were 2WD or 4WD trucks. I can't believe it would be different between the 2 drivetrains. Maybe a LSD diff would look different?

 

Found the post I was thinking of.
It was done on a 2004 Sequoia, however...

https://www.tundras.com/threads/rusted-leaking-rear-differential-cover.27684/page-2#post-1787056

 

I would think any welder/fabricator worth his salt could make one, if you just need a cover.

 

If you want to change your fluid before the spring, or hold onto the current cover for as long as you can, you should be able to fill the differential from the breather in the top. The breather threads into the top of the housing, and you could fill it from there, although it might take a while. I believe the rear diff requires just over three quarts of fluid.

I'm planning on doing this in the next few weeks, I can let you know how well it works if you'd like.

 

Interesting ... thanks for reading through my details! The more I've read about the dffis, I was actually going to replace the breather for good measure. That could be a solution as I believe the drain bolt should be workable based on its location. Good idea! Please keep this link posted or PM me with the outcome. The Amsoil squeeze packs could work nice for this job.

 

I fail to see how a rear diff could be so bad it would leak from changing the fluid.

Those plugs have crush washers to them.

 

I was just thinking that applying enough torque to break lose a rusted plug could crack a brittle cover that is not leaking.

 

I had the same concerns, but finally one day I went for it. I used an impact wrench and that sucker just spun right off! I'm trying to preserve it as long as possible, so I've scraped, wire wheeled, and wire brushed all the loose rust off, followed by rust converter (I use Permatex, but there are other choices) and finally Eastwood Rust Encapsulator (same as POR-15, only different).

It's an endless battle...every time I crawl under my truck I find some rust to be managed, but as long as I stay on top of it it should be good.

 

You make good points. Used axle could be good too but have to find the right gear ratio. I'm not sure I've heard of anyone having a bad rear wheel bearing but it's possible. I've helped change a housing on another tundra before and we installed new bearings, backing plate etc. Just felt it was worth it to never worry about rust ever again, considering the truck had a new frame and that was the last rusty part left.

I also thought you were going to pay a professional welder not that you had access to a welding machine. May be more economical the way you are going about it.

Consider replacing the brake lines on the axle if they look bad. Toyota still sells them. The breather as well.

 

Ive repaired my rear diff cover twice. Found it leaking, drained. Cleaned with wire wheel, sand paper to find rusted pinholes. Cleaned up, and pushed my awl into each hole to make it slightly larger & expose any hidden rust. Cleaned and pushed metal superglue into each one. Painted after cleaning again with POR. Refilled with gear oil. Lasted about 18months. Wash & repeat. Waiting for it to happen again, been 2 years.

 

I just changed the fluid in my rear diff today.

Filling it from the breather hole worked fine, but I’d recommend getting a hand pump to get the fluid into the housing. I bought one of the squeeze bags just to see how well it worked, and well, it didn’t. It was quite difficult to orient the bag in a way that didn’t spill everywhere. The hand pump worked much better.

The drain plug came out easy peasy, for some reason those areas of the differential seem to be much less susceptible to heavy rust.

Make sure you get a new breather, it’s $10 and can prevent extensive damage to your axle seals.

 

or better yet, relocate/extend it up behind the brake light where it will stay nice and clean. Less than $30 for those parts and you can even buy it as a kit.

 

I would agree, but in my case, I blew into/pulled air through mine just to make sure the one-way valve (A) released air outbound with acceptable pressure and (B) Wouldn't allow pressure back in. But I'm not in a rusty area and rarely run through high water. I'll probably still order a valve, but ... there are ways to test.

 

Did anyone ever sort out whether there is a replacement cover compatible with the 4WD V8 trucks? Everything I'm seeing shows they're only for 2WD trucks for some reason.

 

Anyone? Seems the Barnes is the only one that always it'll fit. Can anyone confirm?

 

Sorry, I can’t confirm… but I wouldn’t see why not?

I believe the same axle was used on the 2WD and 4WD models. If someone could chime in and confirm that would be great…

 

Appreciate that and agree it didn't make any sense to me that they'd be different but wanted to confirm with someone who's done it before I order the Barnes unit instead.

 

They're the same.

 

Ok but then why do the units from Dorman and Parts Geek specifically only list RWD compatibly on their sites?

 

No idea.


Toyota part #'s for the axle housing are the same.

 

Just in case you're trying to replace the front axle, of course!

 

@SteveT Did you ever find a cover and try the repair? My rear diff is in a similar state but it's actually starting to leak a little. I've contacted Barnes, who no longer makes one for a 4x4 Access Cab, and Dorman and gotten the same answer you did. I found a welder to do the work but am reluctant to have them try, since the manufacture of the cover says it won't fit.

 

Went with Dorman unit from Amazon, shop said it fit up fine and haven't put a ton of miles on it since but seems to be just fine

 

Appreciate the follow up info on this @ThatYeti . I pressed Dorman yesterday on why the part they make for 2WD won't fit and here's the response I got: "The housings are physically different, shops have tried this with disastrous results" This is the one that seems to be the closest fit: 926-958

 

Will grab a photo later this morning but it fit up 100% after they cleaned up the housing and letting it dry out (used torch) and said it welded up really well too. Only issue I could see is if it holds less oil or if the shape doesn't properly oil the gears but I'm not seeing a major difference from the factory one in either respect. Guessing the answers you're getting from Dorman is just someone in a call center who doesn't have expertise on this part (which I'd never expect them to have) and they're just reading the fitment guide/details back to you

 

Photo attached

 

Old one for reference