Flexplate exchange Question????

**old28** · 11-28-2009, 07:24 PM

Need some help, still learning this nailhead flexplate setup.

I have a 1963 401 motor that had a dynaflow trans at one time. I want to change it over so I can run a ST400 trans. My crank has a 2.90" index on the crank where the flexplate goes on.

Will a flexplate with the ring gear from a 1965 401 fit my 63 crank?

Will I need a bushing to reduce the hole that the converter fits into?

Does the converter bolt straight onto the flexplate without the use of the old triangle plate?

Help Please

Old28

**Dr. Frankenbuick** · 11-29-2009, 03:29 AM

http://www.teambuick.com/forums/show...ght=Trans+swap

http://www.teambuick.com/forums/show...ght=Trans+swap

**old28** · 11-30-2009, 07:53 PM

Dr Frankenbuick:

Thanks for the back threads on this matter. I can see that the only way to run the ST400 with my 63 401 crank setup is to purchase an aftermarket Flexplate with the large crank hole and the bushing to reduce the inside hole for the converter.

I see one setup on ebay out of Portland, OR. for $170 and from Bendtsen's for $295. Any one purchased from these guys? Big difference in price!

Any other suppliers of this Flexplate/Bushing setup?

**ahhh65riv** · 12-01-2009, 10:48 AM

Old28,

Sounds like you have it under control, but I might suggest a few other things that you will need to think about.

First of all, get ahold of Russ Martin at centervilleautorepair.com. He sells flexplates and the pilot bushing you need.

You wont find an aftermarket flexplate for the ST400 that is being produced. You will either have to find a good used one, or have one custom made like I did.

You will also need a starter for the ring gear pattern for the ST400 flexplate(snout length is different). I would suggest one of Tom Telesco's (Telriv) mini starters.

You will need the bracketry and switches and 2-wire harness to activate the switch-pitch feature torque converter. This will depend a lot on what carb(s) you plan on using, you may have to fabricate your own brackets or use the factory set-up, or perhaps one of Bruce Roe's nice and fancy controllers.

It goes without saying... you will need the shift quadrant and adapt the trans mounts.

This is VERY doable. Don't get discouraged!

Erik

**old28** · 12-01-2009, 07:03 PM

ahhh65riv;

Thanks for the information. Bendtsen's has the flexplate to make the convertion from my 63 401 crank to 64-66 setup, nice unit but big $$$$ at $299.

I have a rebuilt 65 starter on hand that will work with the flexplate/ring gear.

I also have a 65 401 flexplate with ring gear and I might just switch out cranks for a 64-66 401/425 unit. I am building my own motor and this may be an easy way.

May not need all the switches as I am looking to buy a ST400 non switch pitch trans from Bendtsen's (they have them both ways) as the unit I have has a large case crack and it is hard to find cases for these trans in Bakersfield, CA area.

As far as mounting and shifting controls it should not be a problem. This motor is going in an "Old School" 1929 Ford RPU hot rod and I have to build almost everything to setup motor/trans/rear end. But I think it will be a lot of fun building as I have always wanted a Nailhead Roadster Pickup and at 64 years young I think I'll get it.

OLD28, Tom

**ahhh65riv** · 12-01-2009, 09:56 PM

That's good news about Bendtsen's. There will be a lot of happy folks to know that they are doing flexplates. That's a great resource. I'm a little puzzled as I thought that with the adapter you can use the 401 flexplate as-is without modifying it.

It's just my own preference, but it would be a shame not to use the switch-pitch feature since you are so close. But then again.. being that that old pick-up is so light there's probably not much to gain unless you were trying to squeeze out all the performance on the track or something.

I have a fresh 65 switch-pitch trans and TC ready to go if you are interested. As a matter of fact I have the complete 401 along with it. I was going to keep together but I'm probably willing to part with..

Erik

**telriv** · 12-02-2009, 02:56 PM

depending on where the crack is, the aluminum is good quality stuff & CAN be welded by a competent welder.

**old28** · 12-02-2009, 06:55 PM

Erik;

The flexplate & crank adapter that Bendtsen's sells will let me put their flexplate that has a ring gear on it like the 64-66 and will fit my '63 crank that has a 2.9 index (64-66 have a 2.5" crank index). I can use a starter from 64-66 short nose or purchase one of Tom's HT units.

The adapter they include with the flexplate will reduce the crank hole down so it will take the TC from the switch pitch trans.

I hope I am correct, if not let me know.

This is all new to me as I have never setup a nailhead before and have ran nothing but powerglide in my nostalgia drag race cars for the past 45 years, but I think I am getting a handle on it.

Tom

I have checked around the Bakersfield area and have not found a good welder to do the alum case. We got lots of oil field welders that do pipe line work and not to many Fab Shops that will do Alum. The crack is in an area that I would say is not as bad as others, about 6" long from the top center bellhousing at the block back towards the main trans, but stays in the bellhousing area. I have no idea on the condition of the trans as it was part of the project I picked up. It looks a little tired.

Thanks guys, Tom w

**nailheadnut** · 12-03-2009, 02:53 PM

Check with Russ Martin up in Grass Valley, CA. He has everything you're looking for. New and used flexplates, the hub adapter, starter motors, transmission mounts, etc.

With the ST400, either s/p or not, you'll need different kickdown linkage from the carb to the trans. The 63 used mechanical linkage, the 64 and later used an electronic set up. Russ probably has the brackets and the switch to help with this as well.

www.nailheadbuick.com