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View Full Version : why is 23 spline better then 21?


Toyquad
03-10-2006, 07:11 PM
for a dual t case..... why is it better to get the 23 spline over the 21.....


im just asking cause when i broke the input to my rear t case... it was the shaft that broke.... behind the splines. The splines were fine. Would a 23 spline have made any difference?

Nutbar
03-10-2006, 07:16 PM
a 23 spline shaft is slightly larger in dia. and the more splines you have the more surface contact area between the 2 coupling surfaces therefore is stronger than 21 spline
[cheers]

sparky
03-10-2006, 07:17 PM
if i am not mistaken it has to do with the type of steel the shaft is made of more hardened then the 21 spline.....i maybe way off base though......[cheers]

sparky
03-10-2006, 07:18 PM
ok i am way off base then...oops......[51]

Big_Ern
03-10-2006, 07:18 PM
I beleive the entire shaft is a tiny bit thicker to allow room for the extra splines, so it might have helped.

To change to 23 spline you would have to change your tranny to a R151F out of a turbo 22re which are hard to find $$$$

Another option is to have your shaft cryo'd. I know marlin sells cryo'd output shafts for $65, So I'm sure you could find someone to treat both input & output for the same price or cheaper.

Big_Ern
03-10-2006, 07:19 PM
Also, what axle gears are you running?

4.10s put a lot more stress on everything up the line from them (ie t-cases) than 5.29's would.

nykoma
03-10-2006, 09:36 PM
more is better,[cheers]

Toyquad
03-11-2006, 06:46 PM
4:10's soooon to be 4;88

Tuner Inside
03-12-2006, 10:30 AM
Not to hyjack but I want to build up a toy doubler but im curious what vehicals the 21 spline where in and which one the 23 spline where in. Also would you get the same strength out of a 21 spline if it was cryo'd vs a non cryo'd 23 spline.

Planing on a 3 reduction section into a toyota tcase in the kick. Sidekick bobbed tcase - yota doubler and tcase. Looking to be 175:1

Big_Ern
03-12-2006, 10:30 PM
21 spline is the most common and is pretty much every gear driven t-case which came behind all 20r & 22r/e's with a standard tranny.

23 spline is the gear driven case behind the turbo 22rte motors with the 5spd R151F tranny ('86 & 87 only I believe) and isn't very common.

I really wouldn't worry about the strength of a 21 spline unit though. Thats what most of the comp guys run, and very few seem to have any problems. But if you really want to be sure, have the 21 input (& outputs) cryo'd on you rear case. The front ones wont see enough reduction/tourque etc to cause a problem.

iif you want to go 23spline, you have to do it in all the cases which could be very $$$. You can also buy 23spline input shafts to convert a 21spline t-case. But again, I personally don't think its worth the $$.

Tuner Inside
03-13-2006, 12:01 AM
Thanks Aaron. Who does the cryo work? Seeing both the yota reduction boxes are going to see some serious torque!

Big_Ern
03-13-2006, 12:15 AM
oh yah, this is your desiel project, right?

As for Cryo, i know Bobby Long will cryo just about anything you send to him, but I'm sure there must be a shop locally that can do it.

I know Owen has figure out the heat treating process used on birfields, but I think the cryo treating they do to R&P and t-case shafts might be a bit different...? I think they heat treat it and then cryogeniclly freeze it as well. Basically I think its just makes the metal softer so that a shock load won't break it. The parts will wear out faster tho.

ToyotaHEAD
03-13-2006, 10:46 AM
The differance between 21 and 23 spline shafts is not in diameter. If you study them closely you will see the 21 spline shaft has a stress riser just behind the slines. (that is where they always break) So when Toyota went to the 23 spline style they machined the shafts a lil differently.

You can mate a 23 spline case to a 21 splined tranny thou a special coupler. AA I do believe makes both the adapter (21 to 23) and plate to adapt a gear case behind a R150. But this plate adapter isnt required on W and G series trannys, exception being the G58.

As for your comment Turner and both cases being the same reduction... Only the rear case will see high torque on its input. (The shaft that breaks) Personal experience now... If you stay with the stock 2.28 gears in both cases, dont worry at all about the 21 splines. If you wanna put lower gears in, do so in the rear case. Still 21 splines will be plenty strong. If you decide you want the gears in the front case YES consider cryo the rear input shaft.

I personally run a dual tcase setup, with a final ratio of 205:1ish. I have 5:1 gears in my rear case. Seems like a waste cuz i have a R151F into the 23 case, into a 21. (my 5:1 gears are in the rear case) And I have never ever had a problem.

Hope this info helps. Cheers

Tuner Inside
03-13-2006, 11:01 AM
I was planning to run just stock yota reduction sections. My curiousity was in what I should have cryo'd since both yota reduction sections with see multiplied reduction from eith the kick tcase or the kick tcase and first yota reduction section. Guess I could just run them and see what blows up.

Big_Ern
03-13-2006, 03:12 PM
The differance between 21 and 23 spline shafts is not in diameter. If you study them closely you will see the 21 spline shaft has a stress riser just behind the slines. (that is where they always break) So when Toyota went to the 23 spline style they machined the shafts a lil differently.

You can mate a 23 spline case to a 21 splined tranny thou a special coupler. AA I do believe makes both the adapter (21 to 23) and plate to adapt a gear case behind a R150. But this plate adapter isnt required on W and G series trannys, exception being the G58.

As for your comment Turner and both cases being the same reduction... Only the rear case will see high torque on its input. (The shaft that breaks) Personal experience now... If you stay with the stock 2.28 gears in both cases, dont worry at all about the 21 splines. If you wanna put lower gears in, do so in the rear case. Still 21 splines will be plenty strong. If you decide you want the gears in the front case YES consider cryo the rear input shaft.

I personally run a dual tcase setup, with a final ratio of 205:1ish. I have 5:1 gears in my rear case. Seems like a waste cuz i have a R151F into the 23 case, into a 21. (my 5:1 gears are in the rear case) And I have never ever had a problem.

Hope this info helps. Cheers


R150 is the V6 tranny which uses the chain driven t-case. And yes, you can get an adapter from either marlin or AA to run a standard gear driven t-case. None of the 4cyl trannies L, G & W series) require an adapter to run 21spline gear drive case except for the turbo R151F which uses 23

Did you need a special dual case adapter to run a 21spline case behind the 23? I always understood that you had to use the same stuff all the way thru

ToyotaHEAD
03-13-2006, 03:31 PM
R150 is the V6 tranny which uses the chain driven t-case. And yes, you can get an adapter from either marlin or AA to run a standard gear driven t-case. None of the 4cyl trannies L, G & W series) require an adapter to run 21spline gear drive case except for the turbo R151F which uses 23

Yes that is what I am saying [36] Except the G58, which is not as common, and has a chain case.

Did you need a special dual case adapter to run a 21spline case behind the 23? I always understood that you had to use the same stuff all the way thru

Yes there is a 23 to 21 coupler.

That little coupler can come in: 21-21, 21-23, 23-23. I have even heard of people cutting up couplers on a leagth and then welding the combination they want together. Not something I would wanna do, but yeah... :eek:

Big_Ern
03-13-2006, 03:45 PM
I've never knew about the G58.. Wonder what years & options it came on? did it use the same chain t-case as the v6?

ToyotaHEAD
03-13-2006, 03:59 PM
Kinda gettin away from the topic at hand, but the G58's are typically found 90-92 4cyl 4Runners. And yes I "think" it is the same chain case. But dont quote on that.

Big_Ern
03-13-2006, 04:05 PM
interesting.

And who cares about getting away from the topic? FiBC, the home of thread Hijacking :D


besides, this is still sorta on topic and good info to know[cheers]

Toyquad
03-15-2006, 02:08 PM
ah makes sense if the shaft is bigger. all i wanted to know thank you....