Official Crawlbox BS thread!

Gotcha. So the machined aluminum seal housing should be interchangeable? If so that's good news.

Pretty sure that was PSUTaco...he's perma banned from TW but I'm sure Homey can get in touch with him.

 

Yep the trans seal housing should be fine...(knocks on wood). I've only ever heard of the actual coupler causing issues.

 

@6 gearT444E

 

Yeah him but he reads stuff here already.

 

Yeah him.

 

Any is much more of an expert on this subject. I’m sure he’ll chime in.
With my set up inchworm originally sent me the housing adapter for an automatic transmission instead of a manual transmission. The only thing I had to do was get the manual transmission housing. It would’ve taken them too long to send me one so I got the measurements for the housing from Wyatt and had one machined to those specs. Eventually inchworm sent me that housing and I returned the automatic one to them. Hence, I have an extra housing.

 

So I'm re-reading this thread again and correct me if I'm wrong, but I'm still going to have a hell of a time finding the proper spline adapter between the 23 spline input on the crawl box and the 22 spline tailshaft on the manual transmission, aren't I?

 

@6 gearT444E

 

You need a seal housing extension on the tailshaft of the transmission as well as the coupler; only inchworm had made that previously even if you had ordered a Marlin box, Marlin bought the coupler and seal extension from inchworm and boxed it all together. The seal housing extension was the one that @HomerTaco got sent the wrong one of, the one from the automatic is different as the seal is a different size. The coupler is a male 22 spline to female 23 spline adapter that allows the crawlbox to mate up to the rear of the transmission.

The 23 spline is the same standard 23 spline count that toyota has used for years, including the FJ cruiser and tacoma transfer case input shafts from automatic trucks. The marlin box uses the "total spline" design where it doesn't neck down at the housing that is supposed to increase the strength and eliminate the weak point at the necked down area. As far as I know, nobody else makes that either anymore unfortunately.

The seal housing extension gets pounded on the output shaft of the transmission with red loctite, then you install the coupler and then pound the seal into the new extension housing. Perhaps low range offroad has the seal, coupler, and extension housing since they bought out inchworm

 

@Littles Attached are the old inchworm instructions. You would need the following parts. These should work for either an inchworm case or marlin or trailgear, the adapter plates are all same design.

160-0011 - Seal Extension - Manual 6-Speed
160-0006 - Oil Seal - 34 x 53 x 8
160-0406 - Coupler - 22 Spline (male) x 23 Spline (female)

 

Thanks for chiming in. I have called YotaMasters and Trail Gear...will try Low Range tomorrow but I'm not too hopeful. The only 22 to 23 spline adapter I have read about was Wyatt from RST who j couldn't get a hold of. I believe he used an inchworm adapter plate and inchworm spline coupler for this application but they are obviously no longer options for me unless by some miracle they turn up used. Unlikely...but I'll keep fingers crossed. Advance Adapters supposedly has something but not Marlin approved according to my call with them today. See below.

If I am reading correctly, in addition to the extension housing being different, the seal is different...meaning I cant put the seal from the AT housing into Homers housing for the MT?

I'll also bring this over from the taco box updates thread, since it's relevant.

 

Thanks man...this confirms what I thought I would need. I'll keep you all posted on my search for that coupler...that's going to be hard to find if advance doesnt make one.

 

Correct, I believe the seal is a different size too, when we were doing Craig's install, the seal did not fit the automatic extension. In reality, you could make the automatic seal work if you machined a custom extension housing that would fit on the 6 speed transmission side with the same dimensions of the automatic seal on the back end. The taco box is the same whether it's going into an automatic or a manual transmission truck, so the ID of the seal that the splines mate up to are the same whether automatic or manual but the OD is different where the seal presses into the extension housing.


I am sure that anybody that is able to make custom axle shafts (moser, dutchman, RCV, etc) would be able to machine that 22x23 spline coupler if you give them the specs on it. Unfortunately I don't have the specs on the length of it, only way to tell would be to remove the crawlbox and measure or if someone has another one lying around to reverse engineer it. The company that made @HomerTaco 's seal extension could probably fabricate another one too. I'm sure the seal is an off the shelf type seal as well.

 

For the length.. would it not be the same as the AT or is the tailshaft a different length too? I have the 23 to 23 spline coupler for the AT

 

I'm not sure on the length to be honest, you'd have to remove the transfer case off a manual and automatic transmission and measure from the back housing of the transfer case to the input of the splines. The automatic transmission output shaft is a male end whereas the manual transmission output shaft is a female. The transfer cases on the automatic FJ cruiser and tacomas have a 23 spline to 23 spline female-female coupler on them from the factory. I would think they would be the same length but who knows with the goofy toyota engineers they probably made them different.

Try asking them for this part# 52-5715. This may also work for the marlin/low range crawler boxes or might be a different length to accommodate the AA transfer case input shaft.

https://storage.googleapis.com/advanceadapters-com/downloads/505715.pdf?1563324283=1

 

Really appreciate all the help here. I was feeling pretty hopeless earlier after talking to Marlin but feel like I'm back on the right path now. I don't mind getting parts made if necessary.

 

No problem, sucks nobody makes these parts for our trucks anymore. I guess I was lucky when I did my install many moons ago and Marlin actually had stuff in stock. Here's a picture I stole from the google image search, you can see the coupler on the left hand side. Like I said, if you can find them specs on the length, you could send somebody the input shaft of the 6 speed transfer case and the input shaft of the crawler box and have them machine you one. If you end up finding one and need someone to order in volume, I'm sure you could make some coin and have no problem unloading the rest of them. I myself would buy one just for a trail spare lol, if that coupler was to break on the trail you'd be shit out of luck.

 

The seal on my truck now is the one that came with the auto adapter. The housing was different but the seal was the same.

I’ll take a pic later when I’m not drinking

 

It’s that spline adapter that’s the missing link I think...

 

That's good to know, for some reason I was thinking the seal was different, but I guess it's just the extension housing.