The Stovebolt Site Forums The Shop Area Driveline Replacing rear motor mounts

I need to replace the rear motor mounts on my 1939 JD, 216 stovebolt. I cannot lift the rear of the engine more than 1/8" off the cross member, making it virtually impossible to get to the bolts holding the motor mounts to the bell housing. The cross member is riveted to the side horns on the frame (4 rivets each side). I am thinking of removing the rivets, making it a whole lot easier to replace the mounts and using bolts/lock washers/ nuts to reattach the cross member. What say you stovebolt guru's?

Rick

Nothing wrong with that idea except, make sure that the cross member is not somehow trapped such that it has to slip out upwards towards motor. There may be a tapered flange or an obstacle or it may not slip out of the "C" channel. At any rate it will be tight and may have to be knocked loose.
Bolting is plenty strong.

I do not know if there is a way to lift the motor higher. Others will advise.

Sounds like a lot of work.

I'm not familiar with the 39 models, but I find it hard to believe that replacing motor mounts is very difficult. This would have been anticipated, and should be easy, certianly not by unriveting a cross member.
What does the shop manual say? Here's the page in 1938 manual http://chevy.oldcarmanualproject.com/shop/1938/38csm157.html

I agree it sounds crazy. Things were not as anticipated back then. I've seen things like that. They only last a year or two until factory changes to common sense. Sometimes a component was attached to another prior to assembly in truck. They thought it was a good idea. Never realizing it was then "locked" for repair. Hope that is not the case. I don't know 1939 either. We all know that for many years maintenance/repair was not a design parameter. Bolt access was not considered. Not much better now. Pull the motor up to get oil pan off? No problem. Drain and pull the radiator to get fan off? No problem. Can't get the inside starter bolt off without taking tire and inner fender off? No problem. Oil spills all over because filter is mounted horizontally? No problem.

In 60-66 GMC, I have seen factory riveted cross members and factory bolted cross members. On the riveted cross member, motor was too long to remove with 4 sp. Could not get 4 sp out after unbolting from bell housing until rotated, rolled, jammed and slipped down. A 150 lb slug of iron waiting to crush your face and decapitate your fingers. Lots of fun. I would have rather gone to the dentist.

In my experience older vehicles are easier to work on, they did think about these things.
Modern vehicles have so much stuff crammed in a small space they are difficult.

1939 should be easy enough.
The 1938 manual says nothing of removing the cross member to service the mounts, nor removing the cab to remove the engine.
You much be able to remove and replace the mounts without much trouble.

I can remove the motor mount bolt/nut going thru the cross member. The angle of the cross member where it is riveted to the frame does not allow any room to get a socket on the lower bolt holding the motor mount to the bell housing. I can get the top bolt holding the motor mount to the bell housing off. The clutch/brake levers and master cylinder bracket allow for virtually no room to lift the rear of the engine up off the cross member more than 1/8". The top the transmission also hits the bottom of the floor board. Not enough room to get to those lower bolts. I had to cut a 5/8 deep socket to 2 inches long just to get to the top bolts. I imagine during assembly back in 1939 the drive train was lowered onto the frame before the cab/sheet metal were installed. I'm going to go back out to my workshop and reassess this dilemma. It definitely needs new motor mounts.

Rick

I'm not familiar with a 39, but on my 59 and the AD trucks the center of the floor above the transmission is removable. Would this allow the engine to be raised up enough? Just a thought.

Update -

I removed the floorboard. Could lift the engine up maybe 3/8". Easier to get to the motor mount to bellhousing bolts from the top inside the cab, than from below. Still had a clearance problem trying to use any 5/8" socket/ratchet combo. Finally, I used a 5/8" spark plug socket that had the 3/4 end fitting for a 3/4" wrench. I cut it to 1-3/8" from end to end, just enough to clear edge of motor mount. That accomplished the task. The motor mounts were definitely toast. Still have to reinstall the floorboard.

Rick

Thanks 4 the update/tip. I'll be tearing into my 48 this weekend.
There's not any rubber left in/on any my mounts.... Only stalactites of dried tar hanging off the crossmembers.

I replaced mine and I believe I actually used a wrench not a socket. Lay on the floor reach up. If I remember correctly.

Don

Don

The head of the bolts were recessed 2" inside the rubber of the motor mount. The cross member is at a 45 degree angle within a one inch of the motor mount. That's why I cut down the spark plug socket to fit.

Rick