The Stovebolt Site Forums The Shop Area Paint and Body Shop Floor boards for a big bolt

I replaced the floor pans on my 6400 by ordering replacemens from Chevs of the 40's. They worked fine except they didn't meet in the center by about 2 inches. That was easy to fix. Yesterday I tried to put the fiberglass transmissions cover in place, and found it rubs on the cover over the emergency brake on the driveshaft. Has anyone run into this before? How did you handle it? Thanks Allen

The Replacement floor boards for mt 54 1/2-ton did not meet in the center either, but I had no clearance issues with tranny cover. Your setup is obviously different that mine though.

I think the difference is that the floor boards were made for a pickup. Mine is a 2 ton truck. No one I know of make parts for the big trucks, but in most cases you can use pickup parts on the cabs and make them work. I believe the pickups had a different emergency brake system, using the rear wheel brakes. The big trucks had the emergency brake on the dirve shaft. There is a round cover over it,that sticks up above the driveshaft causing the problem.

I'll figure something out, just don't know what at this point. If anyone has suggestions, let me know. Or if anyone knows of a parts supplier for the big trucks, that would be welcome news. thanks. Allen

Doesn't matter. The cabs were all the same up into the 5-ton range. The tranny-mount parking brake simply led to another hole being cut in the tranny cover.

GMCpanel: Maybe I don't understand what you are saying, but that doesn't seem right. If you simply cut another hole in the tranny cover, you would have the round cover on the brake mechanism sticking up in the cab. Aside from not looking very good, I think it spins with the drive shaft, and that doesn't seem like a very good idea.

I was talking about the part of the floorboard that covers the tranny also. The original floor boards were badly rusted. They were cut out, and I don't have them any longer, but they must have had a hump or bulge that covered the parking brake in the driveshaft. Not everything on the bigger trucks is exactly the same as the pickups. The fenders are different, the grille is not exactly the same, and there may be other small differences. Thankfully most of the parts are the same, or I would never have been able to restore the truck. There is not enough interest in the big ones to make it worth while for anyone to reproduce parts for them alone. Allen

Allen,

I have a 4400 with the SM420 transmission, which is probably the same as yours. My transmission has the parking brake, in drum style, on the back also. My removable cover is almost flat..the tranny sits quite a bit lower than the cover. Could your cab have "settled" on its mounts?

Stuart

My 1 Ton tranny cover curves up in the middle at the front. I used the one piece toeboard and I had to create that buldge by stretching the metal. From what I have seen, the cabs with the three on the tree had a flatter tranny cover.

Yeah, you need a slot on the right side of the shift lever for the parking brake. Therefore, another hole.

The front clip on medium-duty trucks is VERY different - nothing will interchange, except maybe the individual bars of the grille. The cabs (including the transmission covers) are the same. Either your motor/transmission mounts are really messed up, or your cab mounts have collapsed. My family has two medium-duty trucks, and the transmission in both sits just like a light-duty truck, with the exception of the slot for the brake handle. The transmission should comfortably sit under the cover plate if the cab is sitting properly. I'd get an assembly manual from the parts dealers and start figuring out what's broken.

The bigger trucks have a different cover for the e-brake lever I believe. The cover on my 48 was rotten when I got it so I built a new one. There is a raised section that goes over the top of the trans that extends to the lever. It just so happens to be the same exact size as a 9" x 13" (I think) cake pan that I welded upside-down onto the trans cover in the humps original location. If you didn't know what I used, you would never know,
Scott

Allen,

I have enclosed a link to a picture of the transmission cover in my 4400..hope the link works and hope the picture helps.

http://i5.photobucket.com/albums/y197/nine_milla/trancover1.jpg

Stuart

Automarc. thanks for the picture. Your floor looks exactly like mine. Mine is a 6400. Everyone insists these trucks are all the same, but they are not always exactly alike. For example: I had a terrible time getting my motor to start. Everyone insisted I line up the Ball on the fly wheel with the pointer on the bell housing when I was trying to get the distributor back in place. Wrong: I have a round circle and a triangle on the flywheel. I could not get it to start until I finally used the triangle, and it started on the first try.

I think the same thing may apply here. I could not find brake cylinders for the rear wheels, and couldn't understand what the problem was. I finally figured out that I have a 53 truck, but a rear end from an older one. The older one had a emergency brake that used cables to pull the rear brakes. The rear end still had some of the fittings on the back plate for the cables. I took them off when I put everything back together. My truck has the emergency brake on the driveshaft, or Propeller shaft, as some people call it. There is a drumb like housing that fits just behind the transmission that spins with the drive shaft when the truck is moving. This "drumb" sits up just high enough that it rubs on the transmission cover.

There is something odd going on here, but I don't know what it is. My cab mounts are ok. they are a little rusty, but are still intact and hold the cab in place.

These old trucks have been through so much, rebuilt and changed so many times that you never know exactly what you are dealing with. I have a 62 motor, and used the bell housing from an earlier motor so the rear motor mounts would fit in place. I wouldn't think that would have anything to do with anything, but who knows.

This isn't a big problem. I will just cut a hole in the tranny cover and make a housing of some kind to fill it.

Thanks for the suggestions from everyone. Allen