Auto trans input shaft/TC hub vs crankshaft register

[67dodgedartconv]

When someone says " the input shaft should have 27 splines" are they talking about the smaller inner splined shaft or the larger outer splined shaft? Also, can you use a TC with a hub of 1.55 inches with a larger crankshaft register of 1.8 something inches?

 

[transman]

I guess when you say the hub, you really mean the pilot of the converter. The hub goes into the transmission and the pilot goes into the crankshaft. If it is the pilot you're talking about, no you can't use the smaller diameter hub in the larger pilot hole in the crank. Some will tell you there is a bushing that you can install in the crank to enable you to use the smaller pilot. I guess it works, but IMHO, kind of a mickey mouse fix. From the limited information you've supplied my guess is you've got an early (Late 1962 to 1967) Converter with the small pilot. You haven't said what year the transmission is. The 27 spline input shaft didn't come into play until 1968.

 

[67dodgedartconv]

I guess when you say the hub, you really mean the pilot of the converter. The hub goes into the transmission and the pilot goes into the crankshaft. If it is the pilot you're talking about, no you can't use the smaller diameter hub in the larger pilot hole in the crank. Some will tell you there is a bushing that you can install in the crank to enable you to use the smaller pilot. I guess it works, but IMHO, kind of a mickey mouse fix. From the limited information you've supplied my guess is you've got an early (Late 1962 to 1967) Converter with the small pilot. You haven't said what year the transmission is. The 27 spline input shaft didn't come into play until 1968.

Sorry, don't know the correct terms. Yes, the pilot on the tc that fits into the crankshaft register is 1.55 inches in diameter. The crankshaft register is larger at 1.8 plus inches. I still don't know which of the splined shafts in the transmission is the output shaft. The small inner one has 18 and the larger outside one has 27. My transmission is in a 67 dart. Changing engines to one that has a larger crankshaft register so looks like I need a bushing or a 68 on up transmission to make this work or a custom tc?

 

[fishy68]

The outer splines didn't change count. The inner/smaller shaft that sticks out farther changed count in 68 if I remember right and it's the one you need to be concerned with. If you need a custom converter give Hughesperformance.com a call at 602-257-9591

 

[AJ/FormS]

I once bolted a 65 tranny/TC onto a 68 340, and dropped them into a 65V-100 wagon. I didn't know anything about the register/pilot error. I was in my early 20s, I was just a dumb kid.
I drove the berrys off that combo and never noticed a thing. A couple of years later I sold the roller and moved on; I kept the engine and tranny.
I'm not saying that you should try it. I'm only saying that I got away with it.

 

[Plymouth 65]

Sorry, don't know the correct terms. Yes, the pilot on the tc that fits into the crankshaft register is 1.55 inches in diameter. The crankshaft register is larger at 1.8 plus inches. I still don't know which of the splined shafts in the transmission is the output shaft. The small inner one has 18 and the larger outside one has 27. My transmission is in a 67 dart. Changing engines to one that has a larger crankshaft register so looks like I need a bushing or a 68 on up transmission to make this work or a custom tc?

67dodgedartconv, in order to address the larger 1.8 crank pilot and small input shaft on the early trans you have 2 options. Option 1, just use a bushing in the 1.8 crank pilot and put the 67 trans and torque converter together. Option 2, have the larger input shaft and clutch drum in the 67 trans replaced. You will need a 68 and up torque converter for this option. I chose option 2 for my build. The main reason was because you're selection of torque converter (stall) will be very limited with the smaller input shaft diameter, even customer built!

 

[67dodgedartconv]

Anyone know where I can find the bushing? Been searching this morning but no luck. Thanks for the replies everybody.

 

[fishy68]

I've seen them on E-bay but that's been a while back. Worth a look

 

[67dodgedartconv]

Looked there but no luck. Thanks.

 

[transman]

Go with the bushing if that's what you want. As far as a custom converter goes, that is not an issue, even if you want/need some wild stall speed. The converter shop I worked for did many of these converters, with the 18 spline input shaft and the 1.8" pilot. For any competent converter builder, NO PROBLEM either stock or high stall. There are two ways this is done: one use a front cover that has this size pilot, or secondly machine a pilot of this size and weld it to the front cover. Seen it done many, many times.

 

[67dodgedartconv]

Go with the bushing if that's what you want. As far as a custom converter goes, that is not an issue, even if you want/need some wild stall speed. The converter shop I worked for did many of these converters, with the 18 spline input shaft and the 1.8" pilot. For any competent converter builder, NO PROBLEM either stock or high stall. There are two ways this is done: one use a front cover that has this size pilot, or secondly machine a pilot of this size and weld it to the front cover. Seen it done many, many times.

It's just a matter of budget. This is a stock engine and trans. The transmission is good but who knows for how much longer (no history of the transmission was available when I bought the car). If I got the new converter and then the transmission goes out in a few months then I have to have that one rebuilt and there are few shops where I live and none that I would trust. Then I'm stuck with a converter I cant use on a 27 spline transmission. If I use the bushing and the transmission goes bad then I'm out just the cost of the bushing. Then I would save up and replace the transmission and converter with the 27 spline input and large pilot but it would take a lot longer than I would like. Believe me I would really like to swap it all properly right now but just don't have the funds. Just trying to buy some time. Hope all this makes sense, feel like im between a rock and a hard place. Thanks for passing on some great info that I knew nothing about.

 

[transman]

It's just a matter of budget. This is a stock engine and trans. The transmission is good but who knows for how much longer (no history of the transmission was available when I bought the car). If I got the new converter and then the transmission goes out in a few months then I have to have that one rebuilt and there are few shops where I live and none that I would trust. Then I'm stuck with a converter I cant use on a 27 spline transmission. If I use the bushing and the transmission goes bad then I'm out just the cost of the bushing. Then I would save up and replace the transmission and converter with the 27 spline input and large pilot but it would take a lot longer than I would like. Believe me I would really like to swap it all properly right now but just don't have the funds. Just trying to buy some time. Hope all this makes sense, feel like im between a rock and a hard place. Thanks for passing on some great info that I knew nothing about.

I totally understand, been there before. Good luck on finding the bushing, and you're right, no sense getting a converter built and then find out that the transmission goes sideways on you down the road.