auto to manual conversion

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Old Jan 31, 2019 | 04:37 PM
  #1  
MartinH's Avatar
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From: Vandenberg Village (Lompoc), CA
auto to manual conversion

Apologies if this question is answered elsewhere. There is a lot of info to digest especially for someone new to Oldsmobiles.
My question is this: I have a '69 442 with a 400 ci motor bolted to a TH400 tranny. I want to convert this car to a Tremec 6-speed and don't want to get into this project just to find out the crank isn't drilled for a pilot bushing. Does anyone know if there is a chance that my crankshaft doesn't have a pilot bushing hole? Assume that I have a 1969 400 442 block/crank/engine.
Thanks,
-Martin
Old Jan 31, 2019 | 05:11 PM
  #2  
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I would count on your crank not being drilled for a pilot bearing. Its not a Chevy. Standards were drilled and autos were not. There is an adapter sold that you could use possibly or you could drill it out yourself or pull motor and have a machinist drill out crank?

Last edited by scrappie; Jan 31, 2019 at 05:15 PM.
Old Jan 31, 2019 | 05:21 PM
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Do not use adapter, you will have to cut down front of input shaft of trans., and if engine is auto it will not be drilled as stated above.
Old Feb 1, 2019 | 06:38 AM
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Martin, this isn't a project for the faint-hearted, as you probably know. There's a lot of fab work required and it's not that much more work to drill out your crank for clearance.

Good luck. Overall it is a fun but challenging project and you will enjoy it when you get everything back together.


Old Feb 1, 2019 | 08:24 AM
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VC455- Thanks for the photos. Nicely done! Do you have a photo of the tunnel sheet metal work after welding? I was thinking the same thing. The conversion is going to be a lot of work and pulling the engine then crankshaft won't be that much more. How do you like the transmission?
Old Feb 1, 2019 | 09:57 AM
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Martin, I have photos of the formed sheet metal cover in place before welding. To position the cover for welding, I put bubble wrap over the trans to ensure I had enough clearance.

To clear the end of the transmission, I had to cut through one of the floor supports. You can see the cut supports in the third picture.

To restore the floor strength, I rolled 6 x 1/4" plate into a U-shape and had it welded to the cuts in the floor supports. I tapped three holes in each side of the U to secure a similar U-shaped plate below the floor. That enabled the new floor support to also become a driveshaft loop.

To give clearance for a 3.5" driveshaft, I heated a short section of floor just aft of the cut--I used a jack to push a 4" pipe into the heated area to expand the metal. That allowed full rear-axle travel without contact between the driveshaft and floor.


Old Feb 1, 2019 | 10:13 AM
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Gary- The bubble wrap technique is pure genius. I'm going to remember that. Thanks again for the photos. I'm hoping my 442 won't need quite so much modification. The guy at American Powertrain recommended making a single cut right down the center of the hump and spreading it open like a baked potato. He claimed I will only need 1.5 - 2 extra inches of clearance. We'll see..... Thanks again.
Old Feb 1, 2019 | 01:26 PM
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Martin, the single cut in the center may work Ok. I didn't think of that.

However, look closely at the photo in my first post, you can see numerous hammer-marks on the sheet metal around the scatter-shield. The metal on the sides and top in that area needed about 2" more clearance. The baked-potato cut will need some finessing in that area. You'll have to make cuts from your top slit on down across the kickup areas at the front of the driver and passenger floors (where my hammer-marks show up). The trick will be figuring where to make those two center-to-floor cuts to give enough clearance.

There will still be some sheet metal persuation required, even if the cuts are correct--because the cuts will be in curved areas.

Judge for yourself which method (potato-slit versus new sheet metal cover) will be cleaner and easier.

I did this work before kits were available. Some kits I have seen for our A-bodies do include complete transmission sheet metal covers.
Old Feb 1, 2019 | 01:41 PM
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Originally Posted by MartinH
...American Powertrain... claimed I will only need 1.5 - 2 extra inches of clearance.
That figure is in the ballpark. I had to cut that much off the bottom of my console to keep it at the factory height.

Also consider what to do with carpet, which will no longer fit over that big hump. If you have a console, a center cut will be hidden. However, I found poor fit at the steeper sides of the tunnel and had a custom carpet sewn by the upholstery shop.
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