4 speed to auto crank?

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FomocoReformed

FomocoReformed

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I have a 360 that I plan on mating a 4 speed 833 up to, problem is it came from a truck with an automatic. I read a little doing some searching around that boards that the crankshaft needs machine work in order to fit the input shaft from the trans. But I'm curious what exactly it is that needs to be done and why the crank can't accept a 4 speed?

I also read, if I understand it correctly, that intalling a '94 or newer pilot bearing into the crank will solve the problem without having to do any machine work on the crank. Is that true and if so are there any drawbacks to it?
 
I don't know about ALL engines and ALL cranks, but some were never drilled DEEP enough. So one thing you FOR CERTAIN want to do is to carefully measure from the tip of the gearbox shaft to the box/bell mating surface, then measure from the bottom of the crank hole to the bell / trans mating surface.

Used to be common to cut a little off, only about 3/8" or so.

Otherwise, using the late "Jeep" style pilot bearing/ bushing which mounts in the converter pilot is the way to go there

There was a post some time ago, however, that since this big pilot protrudes further to the rear, it may interfere on some input shafts. Some of them come back from the tip of the pilot surface, and immediately prior to flaring up to the splines area, there is a very small step. Someone on here had problems with that.
 
Some people may throw stones at me, but I actually drilled a few cranks over the years to do this conversion. What I did was measure the outside diameter of a factory pilot bushing and then the inside diameter of the crank pilot. Then I machined up a bushing from solid steel the had a hole in it (that was the same size as the outside dimeter of the pilot bushing) to guide the drill. I then tapped the drill guide into the crank and stuck the drill through the guide and into the crank. This made the hole nice and straight. Once the crank was drilled I took out the drill guide and pressed in the new pilot bearing. It worked better than I thought as the crank material is pretty soft. These were all cast crank motors.
 
Ah so it's a matter of how deep the crank was drilled and the input shaft can't fit all the way? If all I have to do is deepen it a little that shouldn't be hard, I have a crapload of drilling, tapping, and finishing tools I inherited from my grandfather. Or would I not have to cut anything if I just use the "jeep style" pilot bearing?

When you say "cut a little off" do you mean off of the trans input shaft, that would be easier than drilling the crank but would it compromise the strength of input shaft at all?

Sorry for all the questions, I've driven manuals all my life but never tore into them to actually see how everything is connected and functions. I just know automatics from working on them in the army.
 
FomocoReformed said:
When you say "cut a little off" do you mean off of the trans input shaft, that would be easier than drilling the crank but would it compromise the strength of input shaft at all?.
Click to expand...

Yes, the input shaft, and I don't see a problem with strength, my recollection is that around 3/8" is all that is needed.

You may not have to, but MEASURE it whatever you do.
 
I was the one that had recent interference with the step on the input shaft, using the dakota / jeep roller pilot.
With a few other problems.
I have yet to own a small block that was not drilled deep enough for an input shaft.
Some big blocks especally 383 yes.
Still measure what you have.
And if somebody has already cut the input shaft too much to run a factory pilot.
Brewers sells a pilot similar to the roller bushing but it has a brass insert for about 15.00 bucks.

Look here for some problems I experinced, and the step on the input shaft.

http://www.forabodiesonly.com/mopar/showthread.php?t=153715
 
ok ok, I'll definitely have to measure it next weekend and I'll post up what I get as soon as I can. It made me curious if the cranks were actually different because I noticed whenever looking at new cranks online from summit or rockauto or wherever it always specified for manual or for automatic trans.

Sireland, reading through your thread it looks like your problem didn't have anything to do with the "step" on the input shaft but it was the clutch and flywheel that was the problem. Is it still working for you with the newer style pilot bearing?
 
There was about a 0.015 interferece with the the roller pilot style and the shaft.
I ended up usiing a factory plain jane pilot bushing.
If it worked 25 yrs ago, it will still work today.
Major clutch issues where the clutch its self but there was issues with the pilot.
Hope this helps.
 
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