Rear diff / axle assembly repair

My 06’ TRD off-road started leaking gear oil from the rusty rear differential today. Pretty bummed as I already have a long list of small fixes and upgrades I’ve been hoping to do and this will have to come first.

Looks like it’s leaking from the rear side where the “cover” ( I know we don’t truly have a cover) meets the axle assembly (see photo 1+2). I don’t think sourcing or paying for a good used axle assembly is in the cards so I’m considering alternatives.

I’ve seen a few people cut the back of the axle assembly / cover off and replace by welding on a barnes “cover” (linked below) I think this is the route I’m leaning so far.

Questions are:

Do I pull the axle assembly
But or do it in place?

Do I pull the third member / gears / etc..out to do this or just leave in place and give it a really through clean + flushes after?

Am I an asshole if I do a temporary fix with a good cleaning and some JB weld?

Replacemrnt “cover”
https://www.barnes4wd.com/Toyota-Pick-Up-Heavy-Duty-Differential-Cover_p_228.html

Example of repair with kinda unacceptable welds but same process
https://www.tacomaworld.com/threads/rusted-diff-cover-repair-part-1.449412/

Thanks y’all. I can use all the help I can get.

 

JB Weld... problem solved

 

Honestly thank you for showing me that. I think that’s step one for me. Maybe the final step or just a temporary solution until I have the parts and time to cut and weld or replace.

Someone on the 2nd gen fb group said they had the same issue on their first gen and used Toyota fipg and a topcoat of bedliner that stopped the leaks for the 3yrs following that they owned the truck. I guess the fipg is more like rtv but better. He said his was more the rust becoming porous not so much rusted but idk if I can tell the difference?

 

Here's someone who JB Welded theirs and did it "right"

It would probably get you by for a bit in a pinch until you find a real fix

 

So...that photos not of your truck? I was really hoping you could tell me how that bandaid held up lol.

I ordered the barnes cover after work today, $105 to my door for the one made for trucks with the E locker. I have a friend that is a welding fabricator and car guy I know that works for a company I used to do some design / detail / fabrication drawings for that I think I'm gonna reach out to and see if he's open to me paying him to do the cut and weld. I figure we'll leave the axle and gears/third-member in place (hopefully not to too much risk / inconvenience), drain the fluid, move brake lines, cut and grind old housing "cover", clean clean clean (thinking magnets, lots brake clean), weld, clean some more (multiple flushes), final fill (redline 75-90? gear oil?)

If he can't help me out soon I think I'll drain, clean housing, jb weld, paint (looking into that POR 15) product to try and hold me over until i find another welder or my welding skill improve enough to feel comfortable doing this myself.

 

No not my truck, just a thread I found of someone with a similar issue. Keep us posted on how you end up solving it!

 

Hahaha oh man that’s a new one but I guess you gotta do what you gotta do.

 

So I got talked into skipping the temporary fix and going right into the cutting+welding new cover that should be here in a couple days AND doing it via removing the rear axle assembly. I have a few other things I can to do with it out anyways so I guess it’s worth it...

Spent the evening starting to drop the rear assembly and am about halfway or so through. PITA more than I thought.

Got truck up with stands under the frame and a jack under diff and stand under the drive shaft

Got all the small wiring and harnesses (abs + locker) and brake line brackets off

Got the driveshaft yolk off the diff/third member

Got the seized drums off. Real pita, passenger side needs a new drum as old on was disintegrating! Disconnected the parking brake cables (might need new cables they seem kinda seized up...might do shoes while I’m in there). Will definitely be putting in new cylinders I’ve had since right after I bought the truck a little over a year ago with a missing bleeder valve.

Got both the lower shock bolts nuts off and one bolt out, the other bolt is pretty stuck even with the nut removed...gonna have to mess with that.

Tomorrow I’m gonna try to get back at it and drop the rest. I want to price out some parts to see what’s worth being patient with vs just cutting out...(brake lines + u bolts mainly)

The brake lines to cylinders I’m letting soak in pb blaster longer as they didn’t want to break free, I ope they do but I might just end up getting new lines if these are too much trouble.

Get u bolts off...ugh

then it should drop.

wish me luck

 

So I’m looking to order some parts for my 06 trd off-road to replace while I have my rear axle assembly dropped out to cut and weld a new diff “cover” on.

I’m looking to see which of these parts people recommend going Toyota parts vs aftermarket and IF aftermarket which brand / where do you recommend. The parts I’m looking for are:

Rear brake lines (thinking Toyota)

U bolts for leaf spring - axle (thinking aftermarket but who?)

Drums + shoes + drum brake spring kit (thinking aftermarket but who?)

I already have new Toyota brake cylinders I bought a while back and will install now.

E brake lines (thinking aftermarket but who?)

Also considering doing my passenger side axle bearing + seal (maybe)

I think all this includes is the following but please let me know if I’m missing anything.

bearing
Axle seal
Axle housing O ring
Snap ring retainer


If there’s anything else that makes sense to do with this out I’m not thinking of please help me out.

Thanks y’all.
Mike

 

Some updates. In case any future folks are curious about doing this job. Got my new barnes “cover” in and it’s sturdy with good looking welds and shipped faster than I was told. Very pleased with this so far.

got the rest of the rear dropped this evening.



Only part that didn’t go as planned was one on my lower shock bolts was seized in the sleeve of the bushing and I had to cut it to get it free from the bracket on the axle. It’s still stuck in the shock and I’m hoping I can get it out or I’m looking at buying another 5100. Kinda shitty to have to buy a part that wasn’t really bad.



Going to find some time the next couple days to order parts discussed in my earlier post, and clean and prep everything as much as possible for the cut+weld and then reinstall.

also got my por15 in which I haven’t used before but am gonna try to use on the rear axle + diff afterwards and as much of the underside of the truck as possible (leafs?). Any advice on this stuff would be appreciated.






That’s all for now. Will continue to follow up.