crankshaft question....

[wedgee]

ok...on a 68 383, are the crankshafts the same from auto to manual transmissions?
Heres my dellemma ...fourty years ago I had two 383s out of two roadrunners. I put a different motor in my automatic car and my memorie tells me I then rebuilt that motor(automatic) and put it in my 4spd car.... now today, I am restoring my (4spd) car and the crankshaft has a cross threaded bolt hole which I fixed drilling,retapping and inserting an insert. The machinist tells me that the crank isn't correct anyway for the 4spd motor. I always kind of thought I kept the crankshaft from the original motor with the different 383 I stuck in it..is it all in the dampener pulley anyway? the ballancing? post 71 "automatic"blocks I know, from my experience, weren't drilled to accept the pilot shaft from a 4spd trans, yet both cranks I have from those two 68's look and measure identical. whats different?

 

[33 IMP]

I think the only difference is if the pilot hole for the manual trans is drilled or not. Balance weight could also be different depending on pistons, magnum or not.

 

[Runcharger]

Pilot hole. Sometimes they aren't finished to size.

 

[Cranky]

Pilot hole is correct but can't remember if the pilot bearing fit is to size or not....but the hole itself isn't deep enough and that's why you see so many 4 speeds with the nose of the shaft cut off.

 

[PurpleBeeper]

I've been down this road.
1. 4-speed crankshafts are all drilled out in the center of the back crank flange for the pilot bushing to fit inside.
2. Automatic motors "might" be drilled for a 4-speed, but most are not. There will be a small hole in the back of the crank flange, but the pilot bushing won't fit inside it.

The easiest way, if the motor isn't built yet, and you're sure you want to run a 4-speed, is to just use a 4-speed drilled 383 crank shaft. Automatic crankshafts can be drilled out, although it can be tricky to find a machine shop that can do it correctly. You can use a 4-speed with an automatic crankshaft if you cut about 1" off the nose of you transmission input shaft and use a pilot bearing (from a newer 318 engine from a parts store) and no bushing. My motor is set up like this.

 

[Cranky]

I've been down this road.
1. 4-speed crankshafts are all drilled out in the center of the back crank flange for the pilot bushing to fit inside.
2. Automatic motors "might" be drilled for a 4-speed, but most are not. There will be a small hole in the back of the crank flange, but the pilot bushing won't fit inside it.

The easiest way, if the motor isn't built yet, and you're sure you want to run a 4-speed, is to just use a 4-speed drilled 383 crank shaft. Automatic crankshafts can be drilled out, although it can be tricky to find a machine shop that can do it correctly. You can use a 4-speed with an automatic crankshaft if you cut about 1" off the nose of you transmission input shaft and use a pilot bearing (from a newer 318 engine from a parts store) and no bushing. My motor is set up like this.

It's not that hard to drill a crank.....but some won't do it since the best way is to machine an adapter to bolt onto the flywheel flange if you want a true hole. If there was a call for it, maybe some machine shop would make one. All ya need is 3 holes to bolt it to the crank. I made one at work but it's a bit too big to fit the steady rest on the lathe I have at home. At the time I didn't own my own lathe. Figured I'd machine it down some so it would work but I don't do engine work anymore.

 

[440 PHIXX]

I’ve pulled 3 of them over the years from ‘68-‘69, and they were ready for the bushing to be installed. But that was the 3 I had.

 

[Cranky]

I’ve pulled 3 of them over the years from ‘68-‘69, and they were ready for the bushing to be installed. But that was the 3 I had.

I parted out lots of 70 Challengers during the mid 70's and into the mid 80's and most weren't drilled for a stick but some were. Man, wish I had most of those cars now lol

 

[padam]

It’s really easy to use the roller bearing

 

[Cranky]

It’s really easy to use the roller bearing

Yup, probably what I'm going to do with mine. The 440 I have the crank isn't drilled for a stick....that is IF I get that far.

 

[steve340]

Any competent machinist with a large enough lathe with a long enough bed and the appropriate steady would be able to set the crankshaft up and get it running true.
Put the damper snout in the chuck and support the rear of the crank with the steady.
From there drilling/machining a crank to the right sizes for an input shaft bush would be pretty easy.
Especially if you had a 4 speed crank to copy.
From memory the bushing area ID of the crank is 0.940"

 

[padam]

Any competent machinist with a large enough lathe with a long enough bed and the appropriate steady would be able to set the crankshaft up and get it running true.
Put the damper snout in the chuck and support the rear of the crank with the steady.
From there drilling/machining a crank to the right sizes for an input shaft bush would be pretty easy.
Especially if you had a 4 speed crank to copy.
From memory the bushing area ID of the crank is 0.940"

Yeah but tapping a needle bearing into the pilot hole is a lot easier.

 

[33 IMP]

Yeah but tapping a needle bearing into the pilot hole is a lot easier.

..... and cheaper!

 

[steve340]

True - but I was just pointing out it is not super hard or should not be really pricey to get the crank done so you can use the standard bush and not cut the snout.

 

[33 IMP]

True - but I was just pointing out it is not super hard or should not be really pricey to get the crank done so you can use the standard bush and not cut the snout.

It shouldn't be expensive for the procedure, but I'll bet set-up time makes it so. Plus, if the crank is assembled in an engine, a cheaper, easier, just as effective shortcut is welcome.

 

[Curiousyellow71]

Brewers is a good resource

 

[wedgee]

good information,thank you all