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

[klinetime574]

I see what you're saying, but that's an illusion due to the photo being taken on a slight angle.
I actually know you're guessing because you guessed wrong

The dirty one is a 38mm housing that came out of my rig last summer. The clean one is actually the 34mm unit, taken out of a low mileage truck and then stored for decades.

Shoot. It’s hard to tell in pics. I thought I had it sized up. Good tech.

 

[Cruiserdrew]

Super cool about the stepped idler shaft. I used a 34mm case behind my Toybox and it's held up for 10 years at over 200:1 final gearing. I also have a 38mm behind an H55.

In an ideal world, I'd use a new case which I think has all the goodies-38mm shaft, bearings instead of bushings on the output, etc. An FJ60 case converted to manual shift would be choice too, especially with a longer input gear.

 

[tmxmotorsports]

This is what I would like to put to the test. If it's an issue with one version and not the other then that would indicated that the actual outside dimensions of the case are smaller on the 34.
I am going to take some measurements.
It would be strange for AA to come up with a statement like that out of nowhere. However, I am driven by posted information/data and not just what someone said one time, and I have seen no posted evidence for this claim... We'll find out

Yea I wouldn't go off of anything AA states

 

[cruisermatt]

So - while the 38mm version - with or without bearing support hi/low gears - is a longevity upgrade, no argument there, the problem is testing for a quantifiable difference is unrealistic, so we’re back to just word of mouth unfortunately.

I can see no strength increase in the 38 over the 34. I think that’s a complete wash, and it’s not like anyone really breaks splitcases anyways. Again, testing for this is most likely unrealistic.

Anyone disagree? Why?

 

[OSS]

I think this is a case of playing telephone (telegraph?) where someone a looooong time ago (decades ago) made a statement that the later case was "stronger" and other people caught on to it and parroted the statement until eventually it became an urban (and outback) legend. The Internet is FULL to the brim of parroted "facts" based ultimately on nothing substantial. If enough people say the same thing ... It becomes fact, even if it's wrong. Consensus becomes truth even if it's false.

Clearly those two rear cases look identical.

 

[cruisermatt]

The more I look at this picture the more I wish Toyota would have just made them all like this. Impossible for it fall out of the T-case in this configuration like what happened to @Godwin

wouldn't even need the retainer bolt and tab at that point.

 

[orangefj45]

The debate over 34 vs 38 has been going on since 1985 ...... and it’ll continue until 2085 and beyond.
@cruiseroutfit nailed it; find the lowest milage case you can as long as it’s an 83 or newer with the 5th gear Oiler provision and don’t waste another second worrying about it.
I’m sure Toyota had their reasons to increase the shaft OD ( just like they did on the early cases from 25mm to 34mm; after the cases were offered in vehicles ) but in real life, there’s precious little difference between them when it comes to durability.

We’ve been working with a local machine shop ever since we ran the first set of 4:1 Sumo gears ( yes, the prototype set )in one of my trucks.
The 34mm cases can be machined but there’s not much material left when they’re done. At this point we have done enough of them to really dial in our tolerances so we don’t punch thru the side of the cases. The 38mm cases are definitely thicker in that area; roughly 2mm.
Here’s a pic I took at the machine shop. Sending 3 more cases over there this afternoon, all of which will be receiving 4:1 Sumo gear sets.
Happy to help if you guys need any more info or parts.
Georg @ Valley Hybrids, Cruiser Brothers & Long Range America
Shop 209-475-8808
Valleyhybrids4x4@gmail.com

 

[cruisermatt]

The 34mm cases can be machined but there’s not much material left when they’re done. At this point we have done enough of them to really dial in our tolerances so we don’t punch thru the side of the cases. The 38mm cases are definitely thicker in that area; roughly 2mm.

So, the 38mm case would have to be larger on the outside, not the inside, according to what you're saying. Same interior dimensions for both.
I believe you, I'll still be mic-ing the two I have at my shop this weekend and posting just so the difference can be shown clear as day for everyone else. This is the very first time I've heard an actual number put alongside the claim - so thank you for that.

 

[orangefj45]

The late 34mm case and the 38mm case are VERY similar dimensionally. I'm not sure in which areas the 38mm version is "bigger" but I do know that they "react" differently when we machine them as far as how "big" we can go before punching thru the sides of the case.
Maybe I'll drill thru a couple of bad case halves when they come across my bench and then get some thickness measurements in different areas. Cause I have time for that! LOL

 

[cruisermatt]

The late 34mm case and the 38mm case are VERY similar dimensionally. I'm not sure in which areas the 38mm version is "bigger" but I do know that they "react" differently when we machine them as far as how "big" we can go before punching thru the sides of the case.
Maybe I'll drill thru a couple of bad case halves when they come across my bench and then get some thickness measurements in different areas. Cause I have time for that! LOL

Is it at all possible that's it's a consequence of your machine shop's fixturing/setup? And that they've just coincidentally punched through 34mm cases and not 38's? I'm sure there's a fixture we can't see in that picture...

 

[orangefj45]

We used to use a fixture ….... but with this new machine, there's no need for a fixture. Simply clamp the case to the table, let the machine find it's reference points and press the button ……. send some chips flying! It's pretty awesome and takes no time at all.

We've probably done 50 cases this way and have not changed any of the dimensions for over a year. Took lots of trial and luckily not a lot of error.

Georg

Valley Hybrids

 

[orangefj45]

Is it at all possible that ………. coincidentally punched through 34mm cases and not 38's?

Come on Matt, you're not serious, right?!

There's nothing "coincidental" about machining these cases.

LMAO

 

[cruisermatt]

Come on Matt, you're not serious, right?!

There's nothing "coincidental" about machining these cases.

LMAO

It was just a Devils advocate question!
I've done enough machining and been around enough CNCing to know that one keystroke is all it takes to ruin a part. That wasn't meant to be a jab or anything like that, just pondering

 

[orangefj45]

It was just a Devils advocate question!
I've done enough machining and been around enough CNCing to know that one keystroke is all it takes to ruin a part. That wasn't meant to be a jab or anything like that, just pondering

Have you ever machined one of these cases?

 

[cruisermatt]

I haven't yet. You should know I'm not scared to ruin some Cruiser parts though!

 

[LAMBCRUSHER]

The answer to the OPs title question is 4. Did someone already win?

 

[TexFJ]

the earlier 38mm cases that still use a bushing in the output gears versus the later 38mm with bearings in the output gears (truly better with the bearings).

Is this true? I only see one set of TC rebuild kits. No company asks how early the TC was built, only question is whether it's a 34mm or 38mm.

 

[orangefj45]

Is this true? I only see one set of TC rebuild kits. No company asks how early the TC was built, only question is whether it's a 34mm or 38mm.

None of the kits on the market include the bearings for the output gears ( only used on some vacuum shifted cases but all cases in FJ62s ) because the bearings are expensive and they hardly ever need to be replaced.

Hope that helps.

Georg

 

[cruiseroutfit]

Is this true? I only see one set of TC rebuild kits. No company asks how early the TC was built, only question is whether it's a 34mm or 38mm.

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

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

 

[orangefj45]

Nice work Kurt as always!!!!!

We stock the bearings too but hardly ever neeed them for rebuilds at the shop or for customers.