Dual transfer case help !! (1 Viewer)

[pappy]

Reviving an old thread. @pappy - Why did you convert the forward-shift Crawl Box to a top-shift?

Simplicity. No other reason that I can recall.

Also, keep in mind that the R151F is 23 spline, and the transfer case that comes with it is too. Most likely, your donor case will be 21 spine and will need a 23-tooth input gear installed. The adapter needs to match.

 

[Will Van]

Simplicity. No other reason that I can recall.

The top-shift case is simpler than the forward-shift case? Because no shift rails? Is it worth converting to top-shift if I already have a forward shift?

Also, keep in mind that the R151F is 23 spline, and the transfer case that comes with it is too. Most likely, your donor case will be 21 spine and will need a 23-tooth input gear installed. The adapter needs to match.

Yessir, the donor t-case core I recently ordered is a 21-spline top-shift. Perfect opportunity to upgrade to a Marlin 23-spline 4.7:1 Competition gear set in the rear case!

As an aside, the forward-shift transfer case that came with the R151F transmission also came with upgraded Marlin 30-spline front and rear chromoly output shafts. I will have to separate the 2WD/4WD section from forward shift case and install it on the top-shift case (after installing the 23-spline 4.7:1 gears) to take advantage of the upgraded output shafts.

I think I have a pretty good setup, I just need to assemble all the parts in the correct order. And Marlin needs to get the MC08 23-spline Dual Case adapters back in stock!

 

[pappy]

Is it worth converting to top-shift if I already have a forward shift?

If I had to do it over again, I would have kept the forward shift.

 

[Will Van]

If I had to do it over again, I would have kept the forward shift.

Thank you for all the info/advice. Now do you know where I can find a clean/rust-free 1979 to 1985 Toyota Pickup? Ha!!!

 

[chesshircat]

Reviving an old thread. @pappy - Why did you convert the forward-shift Crawl Box to a top-shift?

The reason I ask - I just scored an R151F turbo transmission and forward shift t-case that was rebuilt by Marlin Crawler. Zero miles on both the trans and t-case. I want to run dual cases. My plan was to run the forward-shift case as the Crawl Box, and find a good used top-shift core to rebuild for the rear transfer case.

I've read about people converting a forward-shift case to top-shift because a top-shift case is required for the rear case of a dual case setup. But I've never seen someone convert the Crawl Box to top-shift. Is top shift better?

Top shift is not any better. I like forward shift for the crawl box because it gets the shifter closer to the transmission shifter, more room for crap

 

[Will Van]

Top shift is not any better. I like forward shift for the crawl box because it gets the shifter closer to the transmission shifter, more room for crap

That’s what I was thinking - better interior layout with forward shift. Thanks!

 

[CreeperSleeper]

FWIW, I prefer a top shift crawl box and a triple stick setup like this: Triple shifter

I find it to be the best for shifter clearance and "room for crap".

Here is a pic of my setup:

 

[Will Van]

FWIW, I prefer a top shift crawl box and a triple stick setup like this: Triple shifter

I find it to be the best for shifter clearance and "room for crap".

Here is a pic of my setup:

Thanks for the intel. And cool setup!

Aside from layout, is there any performance difference between top-shift and forward-shift?

 

[pappy]

Thanks for the intel. And cool setup!

Aside from layout, is there any performance difference between top-shift and forward-shift?

No. All they do is move gears around using the same motion.

 

[Will Van]

No. All they do is move gears around using the same motion.

10-4. Thanks!

 

[LN106]

FWIW, I prefer a top shift crawl box and a triple stick setup like this: Triple shifter

I find it to be the best for shifter clearance and "room for crap".

Here is a pic of my setup:

Is this possible to push even further into a forward shift setup? Would have to be clearance issues stock but I wonder with a short throw shifter on the transmission.

 

[natetru]

L52 is a tranny. RF1A is a T-case.

Your tranny with the 22RE is probably a W56B with topshift RF1, 22R most likely a W56A forwardshift. Converting a RF1 forwardshift to topshift is easy I did it at my dinning room table without a kit.

With dual cases you'll wanna upgrade motor mounts especially driver side or increase torque will rip mount apart. Several different methods can buy a "bombproof" mount, use a chain to limit movement. I drilled straight through mount and used a 1/2" grade 8 bolt, trick is listed on Marlin's site. Well thats where I got it years ago. I would tack weld nut to bolt or it will vibrate loose.

I am looking to do the top shift conversion. i did 1 10 years ago and i thought i did it all myself, now i am looking for those instructions again... any help would be greatly appreciated

 

[liveoak]

I don't have info on the top shift conversion but here is a good dual case step by step

http://oppiz.net/pics/Tcase%20Build/Toy%20Transfercase%20Build.html

 

[gnob]

 

[ALX4X4]

Here's how I did my TG top shift.