OK, I'm about ready to install new motor mounts but a bit confused. I read the 38 Chevrolet Manual which is quite simple in regard to instructions until it made reference to "U section plate". I don't know what they are talking about. I also noticed the forward motor mount passenger side has a spacer where the driver side does not. I did not expect to change the transmission mount but now I'm not sure. The oil pan wore against the frame on the transmission end of the engine, I don't want to repeat that. Any advice is appreciated. I need to get my 38 back on the road because I'm probably leaving the left coast and moving to Houston. Thanks in advance.
While it looks simple the drivetrain mounting system in these cars is pretty sophisticated.
The “u-shape” is referring to the front and rear flanges of the transmission mount. My assessment based on your pictures is that for some reason the rubber in the transmission mount is too thick. Therefor the upper stamped piece that is bolted to the transmission is too high. The perimeter of that “the u-shape” does not extend down over the lower flat plate.
I cannot tell if the rubber has swollen that much or if someone tried to rebuild it and put too much material in there.
The idea is that that flange or legs fit over the lower flat plate. So if the drivetrain tries to move forward or backwards those legs hit the front or rear edge of the fixed lower plate and stop the movement.
This sure explains why the oil pan wore.
I have no explanation for why the shim/spacer is in the one front mount. I cannot tell clearly but in one of your pictures it appears that someone has tried to weld something back together and it has broken again.
In simple terms the height of the front mounts and the transmission mount set the position of the drivetrain. The intermediate crossmember fits snugly enough to prevent the rotation of the drivetrain in reaction to engine torque. You install it after the front and rear are set. It does not support any weight.
Rusty Thank you for such a thorough explanation. After looking at my replacement mounts, i see the front are both suppose to have the raised mount. In regard to the transmission mount, the rebuild kit has two pieces of rubber. I guess you use one or two if needed? Someone along the line did some strange things to this car. I will order the transmission mounts next.
I'm sure you have noticed that the configuration of your new front mounts is different than what was installed. Your old mounts had deteriorated until the metal of the mounts was rubbing on the cross member. My '40 has front mounts identical to your new ones and they are in good shape. There is between 1/4 and 3/8" from the cross member to lower metal edge of the mounts. If your back mount has too much "pad" in it the clearance on your side mounts should be excessive ( over 1/16") on both sides with new front mounts. If your clearance on the side mounts is 1/16" or less your rear mount should be OK. I would put the front mounts in first and check the side mount clearance before I tackled the rear mount. It can be a bear to get the transmission high enough to change the mount or pad. Good Luck.
I had no problems raising the transmission high enough to replace the transmission mount on my ‘37.
You do need to disconnect the side mounts first.
I agree that whatever is going on with the existing front mounts is a mess. I would replace them first. Then sort out the rear mount. Last is to shim the side mounts as needed to prevent the engine from rocking.
Thanks everyone for the good advice This all started with a valve cover gasket. I’m ordering a new trans mount as well as radiator hoses, heater hoses, shackle seals, cork crumbled. What will I find next?
Front mounts finally done, lifting engine was a challenge. I borrowed my wife’s Acura jack and used a 2x4 for height and width. I had to rotate the engine by grabbing and twisting from the transmission end and she fell in place. The mounts were completely collapsed and not complete. It amazes me the car kept running. I expect the trans and lateral mounts will be a breeze, I hope, then it will be time to straighten push rods then reassembly. I want her back on the road as a moving project. Thanks for all of the good advice and observations Michael
Thank you fellow restorers, all mounts installed and secured. I normally take stills but captured video this time. I thought the tranny mount would be a breeze but I discovered that you cannot remove tranny mount bolts without removing panel from cabin area. 16 bolts later the tranny mount was installed. The removable crossmember mounts were a and crossmember went In smoothly. Only glitch is priming and painting wherever I find myself. Wiring ignition is next. I bought what I thought was entire wiring did 38 but turned out to be lights only. Ignition wiring nex then straighten bent pushrods. Getting close
