Author Topic: Dual case confusion (noob question) (Read 3277 times)

donutman126 · « **on:** Apr 26, 2007, 05:07:40 PM »

Alright well I have read just about everything and i am still confused about a couple things. I have an 85 toyota extra cab efi pickup. So looking on the marlin crawler overview I have a top shift transfer case. I have a transmission and transfer case out of an 86 carb truck which makes it a forward shift case. I would like to do stock gears in the front case and 23 splines with 4.7 in the rear case. Do i need to convert my forward shifting t-case to a top shift so that both cases are top shift? Thank you for your help

*ROKTOY* · « **Reply #1 on:** Apr 26, 2007, 05:16:13 PM »

NO, Only the rear needs to be top shift.

donutman126 · « **Reply #2 on:** Apr 26, 2007, 05:24:14 PM »

But the transfer case in my truck is already top shift do i just put the forward shift in front of it?

MiniSimp · « **Reply #3 on:** Apr 26, 2007, 05:25:46 PM »

I think you need another top shift, but what do I know.

RRMike · « **Reply #4 on:** Apr 26, 2007, 06:22:52 PM »

Yes you would need to convert the forward shift case to top shift. Easier still is just get a top shift case for less than you can convert yours for.

*ROKTOY* · « **Reply #5 on:** Apr 26, 2007, 07:11:38 PM »

If you have a top shift in your truck right now as a single, then you don't have a foward shift. So if it is a top shift you will need another top shift for the crawl box.

If you are still lost get and post some pic's of your trans and transfer case and we will be able to tell you what you have an what you will need.

donutman126 · « **Reply #6 on:** Apr 26, 2007, 10:22:59 PM »

So you can can do dual top shift cases?

MiniSimp · « **Reply #7 on:** Apr 27, 2007, 07:16:16 AM »

donutman126 · « **Reply #8 on:** Apr 27, 2007, 09:35:40 AM »

So I guess its not worth it to convert my forward shift case to a top shift and just look for another top shift? And if I want to do 4.7 gears in the back case with 23 splines in between do i need some kind of 23 output from the front case? I plan on doing the marlin clocked adapter and twin sticks on the back case. I wanna do this right the first time and make it bulletproof.

RRMike · « **Reply #9 on:** Apr 27, 2007, 09:52:58 AM »

When you order your adapter just tell them to send you a 23 spline adapter and it will work with the 23 spline input on your crawler gears for the rear case.

donutman126 · « **Reply #10 on:** Apr 27, 2007, 10:03:17 AM »

Alright thank you everyone I finally understand how this works now! I got one more question, Would it be worth it to buy a turbo transmission so that i could do 23 splines throughout my dual cases? Or is 21 splines in the front and 23 in the second case one going to be strong enough? I plan on doing the marlin 4 inch trail flex kit with 37 inch mtr's and I wanna build it right the first time so that it wont break. Thanks

toy4x4ota · « **Reply #11 on:** Apr 27, 2007, 11:44:09 AM »

you might not be able to find a top shift t-case for much less than what Marlin offers the conversion for. when i did my duals i did what you are going to do and went with 23 spline and MC08-R10 and twin stick except for i have a forward shifting crawlbox. you are going to be taking the entire case apart anywars so it wouldnt be any more work to convert to top shift, and its easy too! the shift rails come pre clearenced for the gears and everything.

toy4x4ota · « **Reply #12 on:** Apr 27, 2007, 11:50:35 AM »

Quote from: donutman126 on Apr 27, 2007, 10:03:17 AM

Alright thank you everyone I finally understand how this works now! I got one more question, Would it be worth it to buy a turbo transmission so that i could do 23 splines throughout my dual cases? Or is 21 splines in the front and 23 in the second case one going to be strong enough? I plan on doing the marlin 4 inch trail flex kit with 37 inch mtr's and I wanna build it right the first time so that it wont break. Thanks

i have read that having the 23 spline in the rear case is needed because that is when the torque gets doubled, therefore more common to break. but thats not to say that having front and rear 23 spline in not a good thing beacause i would assume that it would be that much stronger to have more splines on both input shafts. if i am wrong here someone please correct me

*ROKTOY* · « **Reply #13 on:** Apr 27, 2007, 12:57:14 PM »

Nope, 23 splines are a good thing.

RRMike · « **Reply #14 on:** Apr 29, 2007, 01:21:33 AM »

Never hurts. I'd love to have it but 650 for a turbo trannie makes it a luxury I can't afford.

toy4x4ota · « **Reply #15 on:** Apr 30, 2007, 04:27:44 PM »

thats why just run 23 spline in rear case

*ROKTOY* · « **Reply #16 on:** Apr 30, 2007, 04:50:06 PM »

All_Set · « **Reply #17 on:** May 01, 2007, 10:13:21 AM »

No one has suggested this yet.

Assuming the '86 tranny works. PUt the '86 tranny in, use the forward shift for the 1st box(since it's a forward shift tranny), use your top shift as the rear box. No extra money out of your pocket.

My only reservation is if you do not know the condition of the '86 tranny 100%. It would suck to do all that work, just to have the tranny die in a couple months.

'86, '85 trannys are the same length so no other mods would need to be done. (except opening up a shifter hole.)

donutman126 · « **Reply #18 on:** May 01, 2007, 01:03:16 PM »

Ya thats what i was thinking about... but I have no idea if the 86 tranny is any good

royota85r · « **Reply #19 on:** May 01, 2007, 04:37:35 PM »

I'm running an r151 trans in my 85 runner. As far as I know all r-151's are foward shift. now with what i know about dual cases. (I'm running 23 spline foward shift front and top shift 23 spline rear). As mentioned earlier the adaptor dictates whether you can run 4.70 gears. the 4.70's are 23 spline only. What I did since I couldn't afford the adaptor and the gears ate the same time is bought marlin's 23 spline input shaft and put it in my rear case (PRESS REQUIRED) If you even think you are getting 4.70's get the 23 spline adaptor. My adaptor is the MC07-10 (rotated 10degrees) Other than some vibration issues with my rear driveline I love it

~tc~ · « **Reply #20 on:** May 01, 2007, 06:45:41 PM »

So, I'm working on putting a crawler behind my 3.0/R150 - can I use a forward shift case for the crawlbox? Or do I need two top shifts?

The top shifts I have been able to find are older - like '83. The "bible" says they have the noisey gears - is that only in the reduction, or is it going to whine in hi too? Will that be fixed when I put the 4.7 gears in the rear box? Any problem running the "tall" tcases?

Duffil · « **Reply #21 on:** May 01, 2007, 07:43:30 PM »

Quote from: royota85r on May 01, 2007, 04:37:35 PM

I'm running an r151 trans in my 85 runner. As far as I know all r-151's are foward shift. now with what i know about dual cases. (I'm running 23 spline foward shift front and top shift 23 spline rear). As mentioned earlier the adaptor dictates whether you can run 4.70 gears. the 4.70's are 23 spline only. What I did since I couldn't afford the adaptor and the gears ate the same time is bought marlin's 23 spline input shaft and put it in my rear case (PRESS REQUIRED) If you even think you are getting 4.70's get the 23 spline adaptor.

hmmm...where'd you hear that? Let's not go feeding incorrect info here.

Quote from: Marlin Crawler Inc.

MC-14003, TS™ 4.70 Gear Set, 21 spline, $449
MC-14004, TS™ 4.70 Gear Set, 23 spline, $449

royota85r · « **Reply #22 on:** May 03, 2007, 02:35:39 PM »

if you have the v-6 then you have to get the adaptor to put a gear drive case where your chain drive case is. all V-6's have chain drive cases. I don't know much of anything about the V-6's so I'm not sure how much more help I can be. If you need help with research let me know I'll help if I can

All_Set · « **Reply #23 on:** May 04, 2007, 11:28:07 AM »

Quote from: donutman126 on May 01, 2007, 01:03:16 PM

Ya thats what i was thinking about... but I have no idea if the 86 tranny is any good

If you do not know the condition, then I'd rebuild the tranny. That's $300 bucks, and if you've never done tranny work before, it might be better to spend that money to convert the forward case to a top case. Marlin has a kit to do this and it is not that bad to do.

RRMike · « **Reply #24 on:** May 04, 2007, 05:48:04 PM »

Bottom line is this:

Find a top shift case. All the rest of this is a big waste of bandwidth. Don't spend $300 rebuilding a tranny to allow you to run the less popular forward shift case to save the $100 the top shift case would cost

Then sell the forward shift case for $75 and you are only out $25 to do it right. Plus you have the added bonus of having a dual t-case setup that will work in any Toyota if you want to swap it in the future or sell it or whatever instead of having a setup that only somebody with a forward shift trans can use.

blazen487 · « **Reply #25 on:** May 09, 2007, 03:43:51 PM »

Convert it to top shift it is required!!!

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