34mm vs 38mm Idler shaft T-cases... What's the real difference anyways? (3 Viewers)

[FJ40Jim]

I didn't read the whole thread re. differences, but...
The gears are different (stronger) cut in the 38 cases.

Also note that early cases only have a cast boss for one fill plug position. Later 34 and all 38 cases have the double boss for 2 fill plug positions. It's a good idea to use a rear case that matches the bellhousing angle.

 

[cruisermatt]

The gears are different (stronger) cut in the 38 cases.

Can you elaborate on this?

 

[cps432]

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

The kit you sold me a few weeks ago included it. I did not use it because I have manual linkage. It also included a spacer-transmission gasket for both the 5 and 4 speed transmissions.

 

[cps432]

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

This is my assumption too.

Great thread. One of the best I’ve read in a while!

 

[cps432]

Can you elaborate on this?

Didn’t they change the way the ring and pinion were cut at some point? I thought I read that somewhere.

 

[cruisermatt]

Didn’t they change the way the ring and pinion were cut at some point? I thought I read that somewhere.

Wut. We're talking about transfer cases here

 

[cps432]

Wut. We're talking about transfer cases here

I know but wouldn’t they make changes in gear cutting across the board if they changed or updated their tooling and machinery? I am not a machinist and have no experience with it... Just spitballing...

I guess we need to wait to hear Jim’s reply.

I thought there was a change in the way they cut gears in general that made them more reliable and easier to set up and match with other gears. The mid eighties got high teq!

 

[GLTHFJ60]

I know but wouldn’t they make changes in gear cutting across the board if they changed or updated their tooling and machinery? I am not a machinist and have no experience with it... Just spitballing...

I guess we need to wait to hear Jim’s reply.

I thought there was a change in the way they cut gears in general that made them more reliable and easier to set up and match with other gears. The mid eighties got high teq!

Maybe the metallurgy is shared, maybe, but the diff gears and tcase gears are very different both in size and in tooth profile.

Diff gears are hypoid, tcase gears are spur and helical. I *think* they can be cut on the same gear hobber machine, but the machine setup is very, very different.

Types of Gears | Rexnord

There are 7 different types of gears used in gearboxes. Learn the function of each type, as well as the applications, industries, and gearboxes that use them.

www.rexnord.com

Perhaps you're thinking of spur gears in really early transfer cases, and helical gears as the improvement? Diff gears in all land cruisers have always been hypoid.

 

[cps432]

Maybe the metallurgy is shared, maybe, but the diff gears and tcase gears are very different both in size and in tooth profile.

Diff gears are hypoid, tcase gears are spur and helical. I *think* they can be cut on the same gear hobber machine, but the machine setup is very, very different.

Types of Gears | Rexnord

There are 7 different types of gears used in gearboxes. Learn the function of each type, as well as the applications, industries, and gearboxes that use them.

www.rexnord.com

Perhaps you're thinking of spur gears in really early transfer cases, and helical gears as the improvement? Diff gears in all land cruisers have always been hypoid.

Right on. Good info!

 

[orangefj45]

Toyota uses two different vendors for their trans/Tcase gears/shafts and for their diff gears.
From what I’ve learned, the machinery used is also very different.

 

[LandHJ45Cruiser]

Do all vacuum operated split cases have bearings on the output gears? I have a European Hj61, manual transmission, vacuum t-case.

 

[SuperDuperCruizer]

This question came up somewhere else. I thought it was true for all transfer cases out of automatics but there may have been some isolated example where it’s not so.

 

[cruisermatt]

I still want to know what is stronger about the later gears

 

[OGBeno]

Actually, there are so many different suppliers:

Aichi Steel Corporation (Toyota Group company):

Asahi Iron Works:

Owari Precise Products:

Daido Steel Corporation:

Tsuda Industries:

 

[OGBeno]

Yutaka Gear and Machinery Corporation: (Owned by JTEKT) and is Toyota's main differential gear company:

IJTT Corporation: Diff carriers and housings:

And about 50 more Tier 2-4 companies.... It goes deep.

 

[cps432]

 

[NearJetties]

Is there a speedo gear set that gets a fj62 case, 4.11s, and H55f close to accurate?

 

[OGBeno]

Is there a speedo gear set that gets a fj62 case, 4.11s, and H55f close to accurate?

Yes.

 

[cruiseroutfit]

I still want to know what is stronger about the later gears

I have sets of brand new OE gears out of our new split t-cases and new Japanese aftermarket (and used OE sets) out of earlier split cases. I've developed tooth count, OD and center to center charts on all the configurations but have never measured tooth engagement width. Perhaps that is what Jim C was referring to?

 

[NearJetties]

Yes.

thanks for confirming I wasn't on a wild goose chase. Digging deeper I found this handy dandy gear calculator from @NocalFJ60

Assuming it's correct I should be almost spot on without changing the tcase speedo gears. A few posts I saw alluded to this but couldn't find any that said it outright.

Gear Calculator (Microsoft Excel) Download

Here is a gear calculator I made awhile back before I put in my toybox and updated it today. I have checked it with my setup and it is dead on. You can download it here but you need Microsoft Excel. This should help answers anyone question about different tire and gear setups...

forum.ih8mud.com