23 spline to 18 spline

[Fishous70]

Is it possible to convert a 23 spline trans to an 18 spline? I have an empty case I was thinking of rebuilding into an 18 spline. It was originally for an abody and I will be putting it into my 71 dart behind a 440.

 

[hemitheus]

Yes. The only difference is the input shaft. (gear ratios aside) White stripe/red. Etc.

 

[68 Notchback]

What kind of HP are you pushing?

 

[cudascott]

:burnout:

 

[RustyRatRod]

I've always wondered how you push horse power.

 

[cudascott]

I've always wondered how you push horse power.

with a wheelbarrow

 

[AJ/FormS]

I think I have only ever had one 18 spline A-833 apart. And it was a coarser gearset. And I have read dozens of papers that say 18 spline trannies are a coarser gearset.You need to get an entire gearset as a pkg.You cannot mix coarse with fine. I have several empty cases that I use as door stops and spacers.
I have had hundreds of 23 spline trannies apart and every single one was a similar cut gearset. Im not saying it ( an 18 spline fine gearset) doesnt exist, only that I never saw it in nearly six years of building boxes on an assembly-line, from 76 to 83.
Or did I completely misunderstand your question?
in which case,Why would you consider buying a box of loose parts to fit into your case? What am I missing?

 

[dukeboy440]

I called brewers last fall about the same question. The guy told me that the only way it was possible is if you had a matching gear set.

 

[SuperStock]

I think I have only ever had one 18 spline A-833 apart. And it was a coarser gearset.

I agree, 18 spline A833 have a different gear set.
The ratio(s) is different to match engine horsepower and torque. The purpose is to optimize the transition between gear shift.

By the way, the one you said you took apart, was it A-body 833 18 spline?

 

[AJ/FormS]

38 years ago, dont recall. Mighta bin. It was just one of thousands of trannies that crossed my bench. Oddly, I do remember a BorgWarner T-10/383 A-body trans crossing the bench.Funny how the brain works.

 

[perfacar]

hi, you can't mix 18 spline with 23 spline gears!!! need complete gear set. also, 18 spline usually uses a 308 front bearing. 23 splines use 307 or 308 bearings. depends on case. which needs larger front retainer. just food for thought.

 

[dukeboy440]

So this brings up this question, as I know it'll be asked, but what levels of horsepower can a 23 spline shaft handle

 

[MOPARMITCH]

So this brings up this question, as I know it'll be asked, but what levels of horsepower can a 23 spline shaft handle

I'd say at least 600 HP

 

[19DART66]

The only thing interchangable between an 18 spline and 23 is the main out put shaft. This is were most of the 18 spline A body trans came from, somebody took a B body trans and put an A body main shaft and tail housing on it. There are 2 gear sets for the 18 spline(2.65wide and 2.44close ratio) and 3 for the 23 spline(3.09, 2.66wide, 247 close) excluding the OD trans. plus a few race gear sets that where sold over the counter. YOU CAN'T MIX gear sets, not between 18 and 23, 18 to18 or 23to23, the whole gearset most be changed. All 18's are coarse pitch gears and the 23's are fine pitch gears, There are different input, cluster, and main shaft gear between each gear set.

 

[Fishous70]

Sorry, Its been a while since my last visit. I guess my question should have been can I get replacement parts for a 18 spline and put them in a 23 spline case for an a body. After reading through the thread i realize it is possible, I just need to find the parts.

 

[Fishous70]

Also I should add the 440 going into the car dynoed out at 650 hp. I don"t remember the torque.

 

[DaveBonds]

HP has nothing to do with wear on a gear or spline. Torque and shock do, though.

The shear torque withstanding on a 23 spline is somewhere in the neighborhood of 750ft lbs.

This changes with shock (how you clutch) and how sticky the tires are/ how much wheel spin it has.

The real question is; what are you doing with the car? The gear ratio is the appeal behind an 18 spline input shaft transmission. The shaft itself is not that much stronger than a 23 spline.

 

[440dartsport]

We built an 18 spline A body trans that's in my car now with 760hp. It gets street driven all summer and then the slicks go on and drag raced in the fall. Haven't broke it yet with 7000 rpm launches. Before the 18 spline I had a 23 spline behind a 625hp 440 and I never broke that one either all though that one never seen the track with slicks.

 

[RS23VOA]

So this brings up this question, as I know it'll be asked, but what levels of horsepower can a 23 spline shaft handle

I have a buddy who has a 55 Chevy drag car and I've seen it stand straight up many times with a 23 spline.