Diff swap out, a couple of questions

[CharlieS]

I was hoping to tackle swapping in my eatons this weekend. The diffs were both built by Zuk, so it should just be an R&R.

Questions:

• The FIPG I ordered isn't arriving in time. What other things have people used? Permatex grey RTV?
• Do used gears need to be "broken in"?
  • I understand there is a 500 mile wear in procedure for new gears.
  • My gears are out of Turbo8's LX, and have lots of miles on them.
  • Do I need to follow the same break in procedure?
  • If not, is there a shortened break in procedure for used gears?
  • Or just send it immediately.
• What do people use for break in oil? I hear I need to do a swap after 500 miles (or something like that) where I put in "good" gear oil. What's the favorite for the break in? Brand? Weight?

Thanks!

 

[chriscosta416]

I use AmsOil sever gear in my past 4wd. I did a diff swap from 4.3 to 4.9s in my Montero and installed a rear air locker. Used Mobile 1 diff oil, followed by Amsoil severe gear after 500 miles

 

[TeCKis300]

I was hoping to tackle swapping in my eatons this weekend. The diffs were both built by Zuk, so it should just be an R&R.

Questions:

• The FIPG I ordered isn't arriving in time. What other things have people used? Permatex grey RTV?
• Do used gears need to be "broken in"?
  • I understand there is a 500 mile wear in procedure for new gears.
  • My gears are out of Turbo8's LX, and have lots of miles on them.
  • Do I need to follow the same break in procedure?
  • If not, is there a shortened break in procedure for used gears?
  • Or just send it immediately.
• What do people use for break in oil? I hear I need to do a swap after 500 miles (or something like that) where I put in "good" gear oil. What's the favorite for the break in? Brand? Weight?

Thanks!

- Is the FIPG for the front clamshell? Or are you thinking of using it for the rear to dress or in place of the gasket?
- As these are previously used, I assume it was a full rebuild with new clearances and bearings? I would say an abbreviated break in is fine, and is what I did. The gears having been in service the parts are likely well stress relieved. Only minor surface re-mating. Any normal driving will be fine. Vary RPM and loads, and just avoid extended high HP loads that build serious heat, meaning high freeway speeds or extended grades at high RPM. Any normal acceleration and spurt is just fine.
- Probably not necessary to replace any break in oil as these gears won't be shedding much of anything. Just surface re-mating.

 

[CharlieS]

- Is the FIPG for the front clamshell? Or are you thinking of using it for the rear to dress or in place of the gasket?
- As these are previously used, I assume it was a full rebuild with new clearances and bearings? I would say an abbreviated break in is fine, and is what I did. The gears having been in service the parts are likely well stress relieved. Only minor surface re-mating. Any normal driving will be fine. Vary RPM and loads, and just avoid extended high HP loads that build serious heat, meaning high freeway speeds or extended grades at high RPM. Any normal acceleration and spurt is just fine.
- Probably not necessary to replace any break in oil as these gears won't be shedding much of anything. Just surface re-mating.

Yes, IIRC, FIPG is for the front clamshell - where the Differential Extension Tube mounts. I have a paper (or whatever that is that looks like paper) factory gasket for the rear.

Yes, Zuk did a full rebuild with new bearings, races and seals. Everything was done and documented to his exacting specs.

Cool. An abbreviated break in sounds awesome. Most of my driving is varying speeds, no highway, so that makes it easy.

Interesting on the oil. Would it hurt to break in with cheap oil and then put the good stuff in after 500 miles? Or is it just a waste and burning money that isn't needed?

 

[CharlieS]

I hadn't looked at them in months, looks like I have some surface flash rust looking corrosion. Any tips for prepping that, especially on the gasket mating surface?

 

[TeCKis300]

Yes, IIRC, FIPG is for the front clamshell - where the Differential Extension Tube mounts. I have a paper (or whatever that is that looks like paper) factory gasket for the rear.

Yes, Zuk did a full rebuild with new bearings, races and seals. Everything was done and documented to his exacting specs.

Cool. An abbreviated break in sounds awesome. Most of my driving is varying speeds, no highway, so that makes it easy.

Interesting on the oil. Would it hurt to break in with cheap oil and then put the good stuff in after 500 miles? Or is it just a waste and burning money that isn't needed?

View attachment 2962334View attachment 2962335View attachment 2962336

Gotcha.

I've heard many use ultra grey everywhere, but permatex has a specific RTV for use with gear oils. Should be easy to find locally?
Amazon product ASIN B0023GM2KK
Sorry I misspoke and shouldn't have said you can't run on the freeway to break in. That's fine. Just avoid higher speed cannonball running that builds heat

Can't hurt to replace break in oil. Just time and money. Could extend a bit more in mileage if you feel like you want to get more value out of the first oil?

For oxidation, you can hit it with these low abrasion style bristle attachments. There's other styles too.
Amazon product ASIN B08JH7FRZ4

 

[CharlieS]

Thank you!

 

[linuxgod]

I'm not a mechanic and I make a lot of bad decisions but if they're used gears I don't think you need to break them in or swap diff oil, really. The break-in is to work harden the gears. These are already hardened. I doubt the mating surface will change with the new setup because at this point they're already "set".

That said you could just buy the cheapest 75W90 dino gear oil you can find, run it for a couple hundred miles, and then swap it for good stuff if you're at all concerned. You need 6.5-7 quarts and so it's probably $30 in cheap oil if you go that route.

 

[CharlieS]

The places I checked didn't have much selection or stock of gear oil, so my choices were pretty limited. Then I almost choked on how expensive the synthetic gear oil was, so it's going to stay in there!

I bought the only package they had of that gear oil friendly permatex. Score!

Now if I could only find the crush washer set I KNOW I had two packages of in my mess of a shop.

I may drain the diffs and remove them tonight and leave crush washers for a tomorrow problem...

 

[CharlieS]

Despite being stressed out about getting the drain plugs out, it was a complete non-event. Like zero drama.

The rear was a 24mm, which is something I didn't have in my trail tool kit, but will going forward. The front was a 10mm(?) allen (internal hex) bit. I think this one is the one where I have a lexus plug with external hex to replace, so don't need to worry about adding it to the trail tools.

Thank goodness for the protective ring around the rear diff plug. It was a bit mangled, but did an awesome job of protecting the bolt head.

The nut/bolts on the rear driveshaft were shockingly tight. They came off with some grunting and not so gentle application of the ball peen hammer on the spanner. Note for the trail tool kit - this takes two 14mm spanners. I wish I'd planned ahead and bought fresh nuts and bolts, but oh well, they're easy to get to, if I decide to replace them later.

Tomorrow I'll tackle the r&r of the diffs. The rear looks easy enough, barring any hassle at the wheel hubs. The front looks a little fiddly, but entirely doable. I'll test out the inner CV tool I picked up a couple of years ago. I'm hoping to get away with just dropping the two lower ball joint bolts and not fully removing the driveshafts. They're currently bent at a wicked angle, so hopefully it works...

I took off the budbuilt skids to gain access and will be swappping them out for the stainless steel set I bought last fall. The makita ratchet makes it even quicker than just a ratchet alone. This time I went for the full package with a fuel skid, Heavy, yes. Great protection, also yes. If anyone wants my aluminum budbuilts and a rival fuel skid, they're on the marketplace.

I'll also be running upgraded diff breathers up to the engine compartment. They need to route the same path as the wiring harness to the Eatons, so it seems like a no brainer.

If I get ambitious, I'll change the oil too. I think I have everything I need on the shelf.

If by some miracle my parts arrive tomorrow (new banjo bolts), and I get really really ambitious and things go a LOT better and faster than planned, I'll throw on new calipers and brake lines (SDHQ). These may have to wait though, since I don't want to reuse the banjo bolts.

 

[CharlieS]

Oh, the front gear oil was pretty dark and old looking. The rear looked like it was a ton cleaner. It may have been serviced, or just lived a happier life away from the heat of the engine and transmission?

 

[CharlieS]

Progress!

 

[bloc]

The torque spec for driveshaft bolts is quite high for something you can usually only get a combination wrench on, and when you look close those are special bolts. Fine pitch, very hard steel.. toyota takes their drivelines seriously.

I usually do the trick of hooking another box wrench end over the crooked side of the open end for more leverage.

 

[CharlieS]

Rear diff is hung up on the sway bar. Likely because I've got jackstands under the axles, not the rear frame, but I can't reposition easily.

Any advice?

 

[CharlieS]

The torque spec for driveshaft bolts is quite high for something you can usually only get a combination wrench on, and when you look close those are special bolts. Fine pitch, very hard steel.. toyota takes their drivelines seriously.

I usually do the trick of hooking another box wrench end over the crooked side of the open end for more leverage.

Yup, tried that at one point too.

 

[CharlieS]

Would taking the sway bar mount off (two bolts just to the right of this photo) be a safe play? I'm thinking it may be tricky to get it reattached. That may be what I try next.

 

[CharlieS]

I got it out. I loosened, but didn't remove, the sway bar mounting bolts.

If I do this ever again, I think the swaybar would come off. I chatted with a guy that did this on facebook, and he took the swaybar off. Live and learn.

 

[empty80]

Rear diff is hung up on the sway bar. Likely because I've got jackstands under the axles, not the rear frame, but I can't reposition easily.

Any advice?

View attachment 2962952

This photo elicited some feels.

 

[CharlieS]

Okay, next roadblock. What is the trick to getting the extension tube splines into the diff splines? I had it all cleaned up, laid a bead of sealant, but couldn't persuade the male shaft into the diff splines. Hitting it with a dead blow plastic hammer didn't budge it. The bolts are too short to allow me to use them to draw it down. Longer bolts maybe?

I took it apart and cleaned the sealant off since I exceeded the recommended working time.

Also, did people clean the last bit if gear oil out of the rear diff? There's a pocket below the level of the drain that still has gear oil in it

 

[CharlieS]

I tried again and it dropped right in.