Author Topic: Twin Stick/Transfer Case questions (Read 5210 times)

rocktoy74 · « **on:** Jan 08, 2006, 06:47:31 AM »

OK so I have an R151F and a single Marlin 4.70 Total Spline 23 spline transfer case In an 84' toy. Also since the R151F Is a forward shift transmission just like the G52 that came In It stock I am gonna either have to swap the 4.7 gears Into a top shift case or convert that forward shift case to a top shift case In order to put the 4.7's In the rear case. I still want to get duals so I can get my stock low range back. I have a couple of questions for you guys. I would also like to get a Twin Stick shifter when I do the dual cases. Since I am running 23 spline all the way through (one Total Spline and one stock Toyota Input) I was wanting to get some opinions of which way I should set this drivetrain up. I was thinking put the 4.7's In the rear and put the Twin Stick In the 2.28 Crawl Box so I could use stock low range In 2wd. Any thoughts or comments would be greatly appreciated. Thanks In advance, Worley

blackdiamond · « **Reply #1 on:** Jan 08, 2006, 07:39:06 AM »

I have not actually done a dual case, but I have looked in to it a bit...

As I understand it, your options are fairly limited with the parts you have.

R151F transmission followed by a fwd shift or top shift* 2.28:1 Crawl Box followed by the top shift 4.70:1 transfer case with twin stick.

The Crawl Box does not affect 4wd, it only provides an additonal low range set of gears (2.28:1L & 1:1H) so a Twin Stick wouldn't have any value/function on a Crawl Box.

To get stock low range in 2wd you would simply put the Crawl box in Low (2.28:1), the Transfer Case in High (1:1) using the left shifter and leave it in 2wd on the right shifter. You will have 3 shifters that all function independently.

Put the 4.70 gears in the transfer case (rear) to reduce the stress.

* I think that you can use fwd or top shift for the Crawl Box, but I'm not positive about it.

rocktoy74 · « **Reply #2 on:** Jan 08, 2006, 08:53:36 AM »

Ok, well AFAIK you have to use whatever case style your tranmission will acccept so In this case It was a forward shifting G52 transmission and swapped to a forward shifting R151F, so this kept my shifters pretty close to the stock positions because the two transmissions share measurements that are very close. The only thing that sucks about this Is I will have to r/r my 4.7 gears to a topshift case or convert It In order to get those gears In the rear where they belong, I definitely agree with you there. Also the gears go with the case because It Is clearenced to accept the gears. I have a couple of cases laying around Including my stock case that came behind my G52 and at least one other forward shift case and one top shift which was given to me because It had a broken Input and I took It apart and put the stock 23 spline Input from my Turbo case In there as my Marlin case had a 23 spline total Spline Input Included with the 4.7 kit. This Is how I will have 23 splines throught. I hope I am not confusing anyone, Thanks In advance Worley

blackdiamond · « **Reply #3 on:** Jan 08, 2006, 08:59:22 AM »

I would agree that it would be BEST to use a fwd shift Crawl box to match the transmission, but it seems like a top shift could be used but would require another hole be drilled in the floorboard. Doesn't Marlin have parts to "cap" the transmission where the shifter on the fwd go though?

rocktoy74 · « **Reply #4 on:** Jan 09, 2006, 02:23:08 AM »

Anyone else care to clear this up for me? Thanks In advance, Worley

blackdiamond · « **Reply #5 on:** Jan 09, 2006, 07:04:44 AM »

I did some looking and the cover plate that I was thinking of is for covering the top shift hole on a fwd shift transfer case, so I was a bit confused. Having said that, I don't know why it wouldn't work other than both t-case shifters would be farther back than ideal.

BigMike · « **Reply #6 on:** Jan 09, 2006, 04:58:12 PM »

Worley,

At first it seems that you are in a better situation then you think, but deeper investigation proves that you will be stuck with some work no matter whatchya do....

It seems that your situation is better because since you have already converted to a 23-spline setup, then it does not matter which case you put the 4.70:1 gears

, since we have never ever seen a 23-spline 2.28:1 Input break.

Quote

I was thinking put the 4.7's In the rear and put the Twin Stick In the 2.28 Crawl Box so I could use stock low range In 2wd. Any thoughts or comments would be greatly appreciated.

Yup, Blackdiamond is correct regarding where the Twin Stick should go. What the twin stick does of course, is allow you to run 2WD Low Range, which you know, but the 4WD/2WD parts only exist in the second transfercase, so this would be the only logical place to run the twin stick. You could install a Twin Stick onto the Crawl Box (it'll bolt up), but the Crawl Box only has one shift rail (for High/Low) so the other twin stick shifter would flop around with no place to go.

Also, bd is correct about the fact that if you are only seaking 2WD Low Range, then you do not need a Twin Stick because with a Dual Case, you can put the 1st case in Low Range and the 2nd case in 2WD-High. Now you would have a 2WD-Low Range. BUT, if you follow my advise to save the trouble of moving your 4.70:1 gear set, then you might want to have the Twin Stick...

...See, you could just leave the 4.7s in the Crawl Box. But now if you put the 1st case in Low and the 2nd case in 2WD-High, then you would be in "Really Low" (4.70:1) Low Range 2WD. The only way, in this case, to have a stock 2.28:1 Low Range + 2WD, would be to have a Twin Stick in the 2nd case, since that is where the 2.28:1 gears would be, if you build it that way.

But, no matter what you do in your situation, you will still be stuck with tearing down two cases to complete the job...

First Option: If you choose to move the 4.7s to the 2nd case, then you won't need a Twin Stick in order to have a 2.28:1-2WD, but you will still need to tear about 75% of the 4.7 case down in order to convert it to a Top Shifter (Remember the 2nd case must be top shifting). You will then ALSO need to tear down a stock 2.28 case in order to build the Crawl Box, and of course you MUST use a 23-spline input in front of the 4.7 case because you have a 23-spline output Transmission.. So you'll be tearing into two cases to do it this way, you'll need an extra 2.28 23-spline input gear, but you won't need a Twin Stick in order to get Stock Low + 2WD.
Second Option: If you choose to keep the 4.7s where they are now right behind the transmission, then you will still need to tear that case down in order to build the Crawl Box, and, you will still need to either (1) tear down the front of a stock top-shifting 21-spline 2.28 case to change the input to a 23-spline input, or (2) tear down a stock 23-spline 2.28 forward shifting Turbo case in order to convert it to a top shifting case. But in this setup, with the 4.7s in the front case, you will need to run a Twin Stick on the back case in order to get Stock Low + 2WD.

Let me know where we are after this.

BigMike

rocktoy74 · « **Reply #7 on:** Jan 09, 2006, 05:41:59 PM »

Thanks for the reply Mike. I think I will move the 4.7 to the rear case just because this seems the most logical and the most popular setup. Whenever you think about dual cases It makes more sense to have the lower gears In the rear case. I am confused about one thing you said though I already have two 23 spline Inputs one of them is the Marlin 4.7 Total Spline currently connected to my R151F In the truck, and the other Is a stock Toyota 23 spline that I Installed In a top shift case that had a broken Input. So I am sorry for asking again but, what do I need to get this accomplished? Thanks In advance

BigMike · « **Reply #8 on:** Jan 09, 2006, 09:37:24 PM »

Quote

I already have two 23 spline Inputs one of them is the Marlin 4.7 Total Spline currently connected to my R151F In the truck, and the other Is a stock Toyota 23 spline that I Installed In a top shift case that had a broken Input.

So you are saying that you've got a complete top shifting 23-spline 2.28 case sitting on the ground right now?

If that is true then save yourself some time and just keep the 4.7s in the front case. You've already gone through the trouble of putting a 23-spline 2.28 input in a non-Turbo t/case, and that is just want you need to do if you were to go with Option Two above.

Then you would just tear off the 4WD stuff from the 4.7 t/case and then build the Crawl Box from that, and then just bolt your 23-spline 2.28 topshift case right behind the 4.7 Crawl Box. It's a direct bolt on, assuming you build a 23-spline Dual Case (with a 23-spline coupler).

Otherwise, you would need to convert your 4.7 case to a top shift, and then tear down that 23-spline 2.28 case and convert it to a forward shift and also build a Crawl Box outta those parts.

rocktoy74 · « **Reply #9 on:** Jan 15, 2006, 03:21:38 PM »

Quote from: BigMike on Jan 09, 2006, 09:37:24 PM

So you are saying that you've got a complete top shifting 23-spline 2.28 case sitting on the ground right now?

If that is true then save yourself some time and just keep the 4.7s in the front case. You've already gone through the trouble of putting a 23-spline 2.28 input in a non-Turbo t/case, and that is just want you need to do if you were to go with Option Two above.

Then you would just tear off the 4WD stuff from the 4.7 t/case and then build the Crawl Box from that, and then just bolt your 23-spline 2.28 topshift case right behind the 4.7 Crawl Box. It's a direct bolt on, assuming you build a 23-spline Dual Case (with a 23-spline coupler).

Otherwise, you would need to convert your 4.7 case to a top shift, and then tear down that 23-spline 2.28 case and convert it to a forward shift and also build a Crawl Box outta those parts.

If I decide to go this route what conversion parts am I going to need? I would really like to move the 4.7 gearset to the back case. Thanks In advance for your time and Input. Worley

rocktoy74 · « **Reply #10 on:** Jan 16, 2006, 01:44:56 AM »

TTT Do I need new shift rods since I will be changing the 4.7 case from a forward shift to a top shift? and these shift rods will have to be ground for 4.7 correct? Thanks In advance. Worley

rocktoy74 · « **Reply #11 on:** Jan 16, 2006, 04:06:58 PM »

skid · « **Reply #12 on:** Jan 16, 2006, 04:28:35 PM »

From what I understand, the easy way would be make the 4.7 forward shift case you crawl box. Put he 2.28 top shift case in back. Then you would only have to tear into one case, the 4.7. I don't see having a 4.7 versus a 2.28 2wd low range as a big problem. All you would need is a dual adapter. If moneys not a hugh issue, go with the twin stick. I can't believe anyone would not be happy with a twin stick.

rocktoy74 · « **Reply #13 on:** Jan 29, 2006, 06:17:59 AM »

Quote from: rocktoy74 on Jan 16, 2006, 01:44:56 AM

TTT Do I need new shift rods since I will be changing the 4.7 case from a forward shift to a top shift? and these shift rods will have to be ground for 4.7 correct? Thanks In advance. Worley

Can anyone confirm If this is what I need to do this correctly? Please help Marlin, Rocky anyone.