34mm vs 38mm Idler shaft T-cases... What's the real difference anyways? (1 Viewer)

[orangefj45]

Here’s another item not included in the kits I’ve come across; OEM Part #36416-36010 for the vacuum pod. We keep these in stock and always ask our customers if they have a vacuum shifted case .....we stock the seal inside of the vacuum pods as well.

Georg @ Valley Hybrids, Cruiser Brothers & Long Range America

 

[TexFJ]

We do, or at least my guys should be asking! We’ve sold quite a few of the TC8690AUTO kits with the additional bearings over the years. We offer the bearings loose too (part# TCB40001). They are expensive, retail is $81.11 each at Toyota and you need two. We’ve had them assembled as the TC8690AUTO for quite a few years. Robbie Antonsen (@powderpig) at Adventure Offroad liked ordering them and I believe I put them together as that kit for him. We have them assembled and on the shelf.

Avail here:

Transfer Case Rebuild Kit - Fits Split Case 8/1987+ w/ Automatic Transmission & 38mm Main Shaft Roller

Transmission Rebuild Kits for Toyota Land Cruiser Applications

cruiserteq.com

View attachment 2284017

The TCB40001 bearings are a half bearing, each kit contains two sets to comprise the two bearings needed. Each TCB40001 comes with two halves.

View attachment 2284027

Thanks for pointing this out guys!!!! One question is why are these split? I'm assuming the bushing wouldn't be split.

I have an 09/87 62 so I may be one of the bushing versions. I have a power-on rattling and hum
that is concentrated around the TC area so I'm about to pull the trigger on a kit. Seems that my gear oil is leaking into the AT due to a bad seal.

 

[orangefj45]

Thanks for pointing this out guys!!!! One question is why are these split? I'm assuming the bushing wouldn't be split.

I have an 09/87 62 so I may be one of the bushing versions. I have a power-on rattling and hum
that is concentrated around the TC area so I'm about to pull the trigger on a kit. Seems that my gear oil is leaking into the AT due to a bad seal.

Check the preload on the rear output flange before tearing it apart. If you have any up-an-down play in the flange, then the rear bearing probably spun in the rear retainer and lost preload. In that case, you should replace the rear extension housing and re-shim the bearing for proper preload. Not difficult to do …... and I'd try that before tearing the case apart.
If it's transferring fluid pretty quickly, then a rebuild is probably a good idea.
Since it's a 62 with a vacuum shifted case, the output gears will be bearing supported.
I'd also highly recommend purchasing and installing one of the long-spline input gears at that point; the output shafts on the automatic transmissions ALWAYS have worn splines ….
We have all of these parts in stock.
Happy to help.

Georg

 

[cruiseroutfit]

Here’s another item not included in the kits I’ve come across; OEM Part #36416-36010 for the vacuum pod. We keep these in stock and always ask our customers if they have a vacuum shifted case .....we stock the seal inside of the vacuum pods as well.

Georg @ Valley Hybrids, Cruiser Brothers & Long Range America

Good call. We do not include those in the standard t-case kit but they are part of a TCVCDKIT (Vacuum Diaphragm Overhaul Kit)

 

[cruiseroutfit]

Thanks for pointing this out guys!!!! One question is why are these split? I'm assuming the bushing wouldn't be split.

I have an 09/87 62 so I may be one of the bushing versions. I have a power-on rattling and hum
that is concentrated around the TC area so I'm about to pull the trigger on a kit. Seems that my gear oil is leaking into the AT due to a bad seal.

That is the bearing design they went with. Not uncommon, we see it in various apps.

 

[DickM]

Great thread. I have been on the fence for low range gears in my 34mm case for a while, so it is awesome to have real facts from the the "hands on" guys to use in the decision making process. Thanks.

 

[ToyotaMatt]

Thanks Kurt / @cruiseroutfit for a full Tech module

this is awesome to digest ....

 

[cruisermatt]

I will gladly take any "worthless" 34mm splitcases that anyone wants to discard after this thread

 

[orangefj45]

Want to send one this way? I pulled my pod apart to get ready for Blackbox update and only then realized I didn't have it

Related but not to current topic. Do you have a drive gear for 6x17 speedo sender? The gear I grabbed earlier disappeared in the blackhole of a basement

Yeah I’ll ship one up to you. Text me during the week to remind me.

G

 

[lcwizard]

Since the 34mm shaft never really had an issue with shear I assume Toyota went larger just for longevity. Theoretically the 38mm should
travel 10% farther with the the same wear. Just a tire that is 10% larger will travel 10% rather given the same number of rotations. ....That and the
effect the larger part has on the frail male sense of self security ...land cruiser porn

 

[Jdog]

I've enjoyed this thread, thanks!

 

[tmxmotorsports]

Any measurements yet Matt? I am just curious. Cool tech thread

 

[cruisermatt]

Sorry, been busy with finals last week and been welding up hundreds of hand sanitizer stands this week kinda forgot about it. When I actually make it to make shop one day I will when I go to clean all the transfer case parts off my workbench

 

[SuperDuperCruizer]

Good discussion regarding the 34 & 38 mm cases. Thanks for posting side-by-side pictures.

After looking at the side-by-side pictures of the idler shafts and idler shaft bearings, a couple things come to mind. You can see the 34mm idler bearings consist of more rollers per bearing than the 38mm idler bearings. This translates into a greater distribution of load between the gear and idler. While distribution of load is typically a benefit, given what was posted about greater wear; I’m wondering if the extra surface contact is actually contributing to friction/wear of the 34mm idlers.

Also, seems like a simple project for a metal lathe to modify a 38 mm idler to be stepped for a 34 mm case. Anyone care to post measurements of the stepped idler?

 

[cruisermatt]

Also, seems like a simple project for a metal lathe to modify a 38 mm idler to be stepped for a 34 mm case. Anyone care to post measurements of the stepped idler?

I see where you’re thinking with that, but think the entire gear set has to match, and the idler gear is different between 34/38mm so I don’t think it would be a simple swap to get the bigger bearing

 

[SuperDuperCruizer]

Yes, no debate there. Swap parts or new gear set to match the larger stepped idler. A less involved solution to machining the case.

 

[orangefj45]

I’ve literally built hundreds of these cases.

Both versions seem to last about the same amount of time/milage.
The 34mm units do utilize more rollers per bearing but they’re also smaller in diameter.
The idler shafts are hardened so machining a 38 down to 34 at the ends would be a PITA; it would have to be ground.
However, we do have stepped idler pins available.

For aftermarket gear sets, we prefer the 38mm cases since they’re slightly “bigger” in the areas where the cases need to be machined for the larger low range gears.

Happy to help.

Georg @ Valley Hybrids, Cruiser Brothers & Long Range America

 

[cruisermatt]

The idler shafts are hardened so machining a 38 down to 34 at the ends would be a PITA; it would have to be ground.

I don't think they're actually super hard, or the hardening process isn't super deep on them. I milled a extra step for a second retaining tab in mine with a regular carbide endmill easily.
Of course not worth it when stepped pins are available off the shelf from Sumo, just thought it was interesting metallurgy

 

[GLTHFJ60]

It could be the difference between case hardening (only a few though thick of carbonized hard steel) vs a solid hardened chromoly shaft.

 

[cruisermatt]

It could be the difference between case hardening (only a few though thick of carbonized hard steel) vs a solid hardened chromoly shaft.

yep, exactly.