66 automatic conversion

[Ernest C.]

I'm getting ready to convert an automatic transmission to a 4 speed. Can anybody point me to a step by step plan? I have converted a camaro,but could use any suggestions.
Thanks
Ernie

[Bob R.]

Re: 66 automatic conversion

I've thought about doing the same thing with my 63. I figure it would cost about $3,500.00 or so for the parts which kind of got me thinking of not changing it.
In 63 you would have to change the exhaust manifold, carburator, entire exhaust system, add clutch pedal, shifter, transmission, exhaust mount at transmission, bell housing and everything in it, clutch cross shaft and linkage, 4 speed indicator on the console. I think if you take out the aim you could list all the items I know I missed some..

[Ernest C.]

Re: 66 automatic conversion

Thanks Bob.
I've actually purchased everything for the conversion.
When I started to convert the 69 camaro, I actually came across a simple step by step list that was very easy to follow. I was just hoping to find something like that for a Corvette.
Thanks again

[Brawley M.]

Re: 66 automatic conversion

Ernest,
I did the procedure on my 67 coupe recently. I did it in the midst of a frameoff resto, so it really wasn't hard. Your frame is already plumbed out for the z bar so you don't have to worry about welding the frame. Don't forget to put your pilot bearing in the crank before mating the transmission to the crank.Access is everything,so you might want to consider a frame off resto.Good luck, Brawley

[Jeffrey B.]

Re: 66 automatic conversion

Ernest,

To replace the pilot shaft bearing in your automatic crank for the input shaft on a 4 speed you will need a special size bearing. A standard bearing will not fit. I found out the hard way by trying to force a standard size bearing into my 327 small block automatic crank. Most people are not aware of the difference as I had 2 different Corvette mechanics give me standard bearings. They were puzzled when I said they did not fit. There is an article in the volume 24, Number 4 Spring 2008 Corvette Restorer magazine on this subject. See page 36 if you have the magazine.

Jeff

[Ernest C.]

Re: 66 automatic conversion

Jeff and Brawlet
Thanks for your suggestions, I found the article in the Restorer on the piolet bearing, and will begin to make this conversion. I know there was much more room to work in the Camaro then in the Corvette.

[Joe R.]

Re: 66 automatic conversion

Hi Ernest:

The issue with the pilot bushing diameter has been discussed extensively in the archives. It appears that *some* engines originally equipped with an automatic had a smaller pilot bushing bore of 1.072, as opposed to the standard size of 1.094. This is not always the case (it wasn't the case on my 67 Powerglide), but it is well documented in the archives.

According to a post by John Hinckley, the NAPA part number 690-034 is specifically designed for the smaller bore size.

I believe that the goal is to have and interference fit of about .001 to .002 inches. In other words, the OD of the pilot bushing should measure about this much larger than the ID of the hole in the crank. Anything larger than this is likely to present problems for installation.

[Timothy B.]

Re: 66 automatic conversion

Ernest,

FWIW, When I replaced the pilot bushing on my 63 #4577 crankshaft, the finished hole measured 1.084 so I had a standard bushing turned to 1.086 for a .002 interference fit. I have no idea why this crank was not lathed to the correct size except to say someone mentioned it is not original to the car and could be from a automatic transmission engine.

You can see in the picture how the old bushing looked after someone installed the 1.094 bushing. After carefully measuring, the new bushing tapped in just fine.