Transfer Case / Driveshaft Math

[SAR_Squid79]

Okay - in preparation for my 4WD Conversion, I took some measurements today. I want you guys to check my math. I have to get my Front Driveshaft Lengthened, and my Rear Driveshaft Shortened, and these measurements have to be right!

If someone with a 98 - 04 Tacoma, with a stock Tranny & T-Case can doublecheck my measurements, that would be a big help too.

Here's what I've got:
Driveshafts were measured from output flange -to- Center Support Bearing (Center of bolt)

Prerunner:
Tail-housing -to- Rear Output Flange = 6"
Driveshaft = 39 1/2"

Stock 4WD:
T-Case + Tail-housing = X"
Driveshaft = 27 1/2"

My 4WD Conversion:
Adapter Plate Kit = 8 1/2"
T-Case = 12 3/4"
TOTAL LENGTH = 21 1/4
Stock 4WD Driveshaft will need to be shortened 3 1/4"

My Math:
39.5" + 6" = 45.5" (amount of space from CSB -to- Transmission)
45.5 - 27.5 = 18" ( X = 18" [stock 4WD T-case])
18" - 21.25 = -3.25

So - Stock 4WD D-Shaft = 27.5 - 3.25 = 24.25"
24.25" + 21.25" = 45.5" = amount of space from CSB -to- Transmission

Sound about right?

Jim @ Inchworm told me that I would need to Shorten/Lengthen my Driveshafts by about 4". Are my Stock 4WD Measurements off? My measurements are all based off of mathematic calculations - I don't actually have a stock 4WD to look at and/or measure.






















One more thing:
In the pictures above, I noted the placement of the Speed Sensors. I've got that down. But what in the hell is this:

[sbechtold]

This is the transfer indicator switch. In other words, it's the 4WD indicator switch. When you shift into 4WD this switch causes the 4WD light in the dash to light up. As for the drivelines I can't help, but I would recommend waiting until you have it all installed before having your drive lines made up.

BTW, nice to see another Lefty owner.

[SAR_Squid79]

Oh ok - I don't even think I have that light in my dash... I'll have to ask Harold (Interex). Otherwise, I'll just zip-tie this wire out of the way.

[Voimakas]

Lefty?
As in left hand front output? (yes, I'm a frickin noob)

[george.arnold]

Originally Posted by Voimakas

Lefty?
As in left hand front output? (yes, I'm a frickin noob)

bingo

[Wes]

I just got done efiling so sorry no numbers look good right now...
You using your stock rear driveshaft and a front you bought?
Main thing is either get it installed like dude said or just measure from where one blts to the next and subtract that from center support to where the front one bolts. I want to say mine before the crawler was 19 3/4 rear output to center support? Or maybe it was 28 1/4? I forget.
I wouldn't trust anyone elses numbers too much man- somehow these things are all different. Measure mounting surfaces if you must though- all you can do really. 1/4 - 1/2 inch wont matter too much- that carrier support is slotted and the rear splined

[mojavehanna]

I would wait until its all bolted in or at least mocked up and then measure inside to inside of each flange at the 3 o'clock position to get accurate measurements. It costs too much to do it twice and you'll only save a dayor two anyway, which probably wont make much difference b/c something else will go wrong and you'll have to order a part or something. Like Wes said, somehow they are all a little different.

[Interex]

Originally Posted by SAR_Squid79

Oh ok - I don't even think I have that light in my dash... I'll have to ask Harold (Interex). Otherwise, I'll just zip-tie this wire out of the way.

Yep, the bulb is there and can be wired up very easily. Go down to your Locker ECU (located under the driver side kick panel) and take a look at the harness going into the ECU. There should be a GREEN wire going into it. This is the 4WD indicator light. Since we are PreRunners, the wire isn't actually used by the locker ECU but that doesn't mean that we can't use it. What you want to do is set one side of the t-case sensor to a ground and wire the other side into the cab. Tap the GREEN wire to this t-case sensor and your 4WD light will come on once your t-case is shifted into 4WD.

[padesertboy]

I would have just bought a 4x4, too much work/mods to go wrong.

[=ACID RAIN=]

Ha, coming from a desert rat. Y'all put so much work into those crazy sand-running rigs that this is like making a sandwich in comparison. It's just an adapter and t-case. Even a simple one-stick divorced setup requires more work, and let's not even mention what goes into a two-stick crawler.

[=ACID RAIN=]

Oh hey squid, question:

It looks like you're keeping your stock 2WD tranny, right? How much was that tail adapter from inchworm?

[Interex]

Originally Posted by padesertboy

I would have just bought a 4x4, too much work/mods to go wrong.

The mod is easily done either using all STOCK parts or the route that Jamie is going by simply adding an adapter to the transmission. A converted PreRunner is just as reliable as a factory 4x4.

[SAR_Squid79]

Originally Posted by =ACID RAIN=

Oh hey squid, question:

It looks like you're keeping your stock 2WD tranny, right? How much was that tail adapter from inchworm?

That is correct. With the adapter kit from Inchworm, I am able to mate a Transfer Case (stock, or custom) to my existing PreRunner Transmission. The Adapter Plate Kit was $650. I went this route because

1.) Switching a Transmission is a PITA
2.) My Truck (and transmission wiring harness) is "California Emissions"
3.) I know where my transmission has been, and how well it's been maintained.
4.) Last year I spent a lot of money to have my transmission upgraded to better handle the extra power from the Supercharger.

[SAR_Squid79]

Originally Posted by Interex

Yep, the bulb is there and can be wired up very easily... [Yadda, yadda, yadda...] and your 4WD light will come on once your t-case is shifted into 4WD.

Thanks Harold!

[=ACID RAIN=]

Originally Posted by SAR_Squid79

That is correct. With the adapter kit from Inchworm, I am able to mate a Transfer Case (stock, or custom) to my existing PreRunner Transmission. The Adapter Plate Kit was $650. I went this route because

1.) Switching a Transmission is a PITA
2.) My Truck (and transmission wiring harness) is "California Emissions"
3.) I know where my transmission has been, and how well it's been maintained.
4.) Last year I spent a lot of money to have my transmission upgraded to better handle the extra power from the Supercharger.

Excellent, thanks

I may go this route as well. With only 17k on my tranny, it seems like the best route to go for me too. What t-case did you get?

[Texan1983]

hey, were you at these days jamie? if you are not to far let me know when you are getting serious, i'll come out if you need a hand (got to get you ready, moab is getting close!)

otherwise good luck man, looks as though things are getting close!


you really have 39 1/2" before your center support bearing? other wise your math sounds right... but if you can, the best way would be to bring the truck in with everything mounted up and let them measure and look at you set up to deturman what you need. other wise measure stock and subtract what you are adding.

good luck man!

[SAR_Squid79]

Originally Posted by Texan1983

deturman

You really are from Texas!

I'm in Lake Bluff, IL - about 5 - 5 1/2 hours from you. The guy that regeared my front diff still has it. As soon as I get that back from him, I'm going to install my spindles, hubs, Diff, CV's, Camburg UCA's, and Donahoes all in one day.

Then all I'll have left to do is the T-case, Shifter, x-member, and D-shafts another day. I really want to have this done inside of the next 4 weeks.

I need my truck every day, so I have to figure out a way to mock everything up, so I can at least get an accurate measurement of the Rear d-shaft and still be able to drive my truck.

If you seriously want to come lend a hand for either phase - give me a call. It would help to have your truck to look at for reference, and you can crash at my place, and we can drink beer!

[SAR_Squid79]

Originally Posted by =ACID RAIN=

Excellent, thanks

I may go this route as well. With only 17k on my tranny, it seems like the best route to go for me too. What t-case did you get?

I got the Inchworm "Lefty" Gear-Driven T-case, with 1:1 High Range, and 5:1 Low Range, setup with FROR Twin Sticks. $1700
(http://www.inchwormgear.com/store/pr...roducts_id=985)

(With the T-case setup for Twin Sticks like it is, the shifter lines up perfectly to come through exactly where the stock shifter would be)

[Texan1983]

hey give me a break, i have been drinking a little... (maybe more?)

anyways, let me know when you are getting closer, i might be up for a road trip! you got to tell me when you are doing it so i can try to make it on my off days (despite what you think, i do work every once and awhile!) just want to make sure you have no excuses and make it out to moab with us! it's coming up fast!

let me know man!

[SAR_Squid79]

I got my Driveshafts back from the shop yesterday!

Cost me $320 total, but they did an excellent job - 3-day turn around, and they even replaced the pesky center support bearing on the rear D-shaft.

I think I'm gonna go back to them and have them make me a F & R trail spare after my conversion is done.

I've got my fingers crossed that my measurements were correct. Now all I'm waiting for is BUDBUILT for my crossmember! ...I'm trying to give him my money, and I can't get him to return my calls!

[NorcalPR]

Originally Posted by SAR_Squid79

Okay - in preparation for my 4WD Conversion, I took some measurements today. I want you guys to check my math. I have to get my Front Driveshaft Lengthened, and my Rear Driveshaft Shortened, and these measurements have to be right!

If someone with a 98 - 04 Tacoma, with a stock Tranny & T-Case can doublecheck my measurements, that would be a big help too.

Here's what I've got:
Driveshafts were measured from output flange -to- Center Support Bearing (Center of bolt)

Prerunner:
Tail-housing -to- Rear Output Flange = 6"
Driveshaft = 39 1/2"

Stock 4WD:
T-Case + Tail-housing = X"
Driveshaft = 27 1/2"

My 4WD Conversion:
Adapter Plate Kit = 8 1/2"
T-Case = 12 3/4"
TOTAL LENGTH = 21 1/4
Stock 4WD Driveshaft will need to be shortened 3 1/4"

My Math:
39.5" + 6" = 45.5" (amount of space from CSB -to- Transmission)
45.5 - 27.5 = 18" ( X = 18" [stock 4WD T-case])
18" - 21.25 = -3.25

So - Stock 4WD D-Shaft = 27.5 - 3.25 = 24.25"
24.25" + 21.25" = 45.5" = amount of space from CSB -to- Transmission

Sound about right?

Jim @ Inchworm told me that I would need to Shorten/Lengthen my Driveshafts by about 4". Are my Stock 4WD Measurements off? My measurements are all based off of mathematic calculations - I don't actually have a stock 4WD to look at and/or measure.






















One more thing:
In the pictures above, I noted the placement of the Speed Sensors. I've got that down. But what in the hell is this:

Jamie,

My stock t-case measures 12.5 from the front of the t-case to the flange.

The driveshaft from the mounting flange to the mounting flange after the support bearing is 31".

Note that this is with a manual tranny, pushbutton 4wd transfercase.

[SAR_Squid79]

Originally Posted by NorcalPR

Jamie,

My stock t-case measures 12.5 from the front of the t-case to the flange.

The driveshaft from the mounting flange to the mounting flange after the support bearing is 31".

Note that this is with a manual tranny, pushbutton 4wd transfercase.

LOL! Thanks a lot for those measurements but it's too late now! The D-shafts have already been resized. All I can do now is cross my fingers and hope that I'm as smart as I think I am.

[Texan1983]

Originally Posted by SAR_Squid79

LOL! Thanks a lot for those measurements but it's too late now! The D-shafts have already been resized. All I can do now is cross my fingers and hope that I'm as smart as I think I am.

hell i called bud buit and got an answer the same day... even shipped the skids i bought that day! got them a few days later... good guy, not sure why you are having problems, but give him a chance, he will take care of you...

[SAR_Squid79]

Since I know a few others are currently preparing for a PreRunner - to - 4WD conversion, I need to update this thread with results...

It ended up that my math in this thread was correct! Apparently that high-school algebra paid off after all...

My rear driveshaft that I used for the conversion was a stock Tacoma 4WD shaft. I had 3 1/4" taken out of it, and it made it exactly right for use with my Inchworm Lefty, and PreRunner adapter kit.

So basically if you're using Inchworm parts like I did, whatever driveshaft you're using needs to be 24 1/4" long (measured from the forward flange to the center support bearing).

If you're using all OEM parts, and doing the transmission swap and all that, your driveshaft needs to be 27 1/2" long. If you're modifying your PreRunner driveshaft you would need to have 12" taken out of it.

If you're modifying a PreRunner driveshaft for use with an Inchworm conversion, you would need to have 15 1/4" taken out of it.

Hope this helps someone out.

[HillBilly_Young01]

Originally Posted by SAR_Squid79

Since I know a few others are currently preparing for a PreRunner - to - 4WD conversion, I need to update this thread with results...

If you're using all OEM parts, and doing the transmission swap and all that, your driveshaft needs to be 27 1/2" long. If you're modifying your PreRunner driveshaft you would need to have 12" taken out of it.

Hope this helps someone out.

thanks buddy!!!!!

[tacomarotto]

Originally Posted by SAR_Squid79

Since I know a few others are currently preparing for a PreRunner - to - 4WD conversion, I need to update this thread with results...

It ended up that my math in this thread was correct! Apparently that high-school algebra paid off after all...

My rear driveshaft that I used for the conversion was a stock Tacoma 4WD shaft. I had 3 1/4" taken out of it, and it made it exactly right for use with my Inchworm Lefty, and PreRunner adapter kit.

So basically if you're using Inchworm parts like I did, whatever driveshaft you're using needs to be 24 1/4" long (measured from the forward flange to the center support bearing).

If you're using all OEM parts, and doing the transmission swap and all that, your driveshaft needs to be 27 1/2" long. If you're modifying your PreRunner driveshaft you would need to have 12" taken out of it.

If you're modifying a PreRunner driveshaft for use with an Inchworm conversion, you would need to have 15 1/4" taken out of it.

Hope this helps someone out.

THANKS FOR THE MEASURMENTS!
very helpful.

i think im getting back on track with this conversion. (my dad is still skeptical since its "his truck") but i really like the looks of this route with the inchworm adapter and also id be able to persuade my dad with this route much easier.

would it be possible for you to post some pictures of the install from inside the cab? from the diagram you posted up it looks like the shifter would almost be bcomming out where the arm rest is...

[tacomarotto]

oh ya one more question. how do i go about installing the adapter? must i remove my transmission to put it in place or can i just crawl under there and get to work?

[SAR_Squid79]

Originally Posted by tacomarotto

oh ya one more question. how do i go about installing the adapter? must i remove my transmission to put it in place or can i just crawl under there and get to work?

Fortunately I had access to a lift. But there's no need to pull the transmission. You just remove the rear d-shaft, disassemble the tail section of the PreRunner Transmission, install the adaper kit, and bolt up the t-case.

The 2 hardest parts (because I was doing all the work alone) was hammering the coupler on to the transmission output shaft, and manhandling the Lefty into position, and getting the bolts started (re-emphasize I did that all BY MYSELF!!!).

[tacomarotto]

Originally Posted by SAR_Squid79

Fortunately I had access to a lift. But there's no need to pull the transmission. You just remove the rear d-shaft, disassemble the tail section of the PreRunner Transmission, install the adaper kit, and bolt up the t-case.

The 2 hardest parts (because I was doing all the work alone) was hammering the coupler on to the transmission output shaft, and manhandling the Lefty into position, and getting the bolts started (re-emphasize I did that all BY MYSELF!!!).

do u think it will be easier since im not getting the lefty?

[SAR_Squid79]

Originally Posted by tacomarotto

do u think it will be easier since im not getting the lefty?

Yeah - shouldn't be as heavy.