Les Andrews: Trimming of Motor Mount Rubber

[BRENT in 10-uh-C]

Originally Posted by 1930-Pickup

I'm at this point now, but there is no way I have enough gap to install the parts like this. Frightening words like 'bent frame' run though my head, but there is no damage anywhere. There is some frame sag, but I don't think it would cause this problem...would it?

From my experiences, ...Yes.

[Purdy Swoft]

The last two motor mount pad installations that I did was late in 05 and early in 06 . The pads have always seemed too thick to me . I have a frame spreader but I thinned the pads a bit on the last 2 installations . I have never trimmed any mount pads that I've ever installed . Trimming the lower L off the pads makes no sense at all to me and I woildn't do it. Trimming the lower pad will lower the engine and transmission in the frame unless a person is using float-A-motor mounts . Lowering the engine and transmission in the frame brings the torque tube and radius rods awfull close to the service brake cross shaft . If there is any sag in the frame, the rear radius rods will more than apt drag against the cross shaft and interfere with the application of the brakes .

[1930-Pickup]

Originally Posted by BRENT in 10-uh-C

From my experiences, ...Yes.

Ugh, you know exactly what I don't want to hear Brent!

The exact severity of frame sag is TDB. Some if the sag is from the frame, I'm pretty sure of that. And some only appears to be frame sag because the old motor mounts are now sitting on the bottom of the main frame (so the low-sitting transmission is even closer to the service brake cross shaft).

Regardless, I have a couple thoughts brewing in my head and I'll give them a try tomorrow.

[1930-Pickup]

Originally Posted by Purdy Swoft

The last two motor mount pad installations that I did was late in 05 and early in 06 . The pads have always seemed too thick to me . I have a frame spreader but I thinned the pads a bit on the last 2 installations . I have never trimmed any mount pads that I've ever installed . Trimming the lower L off the pads makes no sense at all to me and I woildn't do it. Trimming the lower pad will lower the engine and transmission in the frame unless a person is using float-A-motor mounts . Lowering the engine and transmission in the frame brings the torque tube and radius rods awfull close to the service brake cross shaft . If there is any sag in the frame, the rear radius rods will more than apt drag against the cross shaft and interfere with the application of the brakes .

Purdy-

I'm glad you said that about not trimming the lower leg of the 'L' rubber pad.
I don't like the idea of trimming it off for the same reason that you cited.

I had to put some spacers under the mounts for the brake cross shaft to keep it from hitting the radius rods. The good news is there appears to be little effect on braking by adding those spacers, although I sure didn't want to do it. It's a temporary measure, besides, the brakes have several other issues as well. Yes, a full blown brake job is on the radar, but the brakes are still working reasonably well...for now.

Why did you not use a frame spreader for the last two pad replacement jobs?

How did you thin those pads? Did you use a belt sander? I assume you removed the three nubs for the frame holes as well then?

[Tom Wesenberg]

I've never trimmed a rubber pad for the motor mounts, and I've only needed to spread the frame on the first engine I installed. If the steel sleeves are hard to push into the rubber holes, give them a shot of WD-40 or Vaseline.

[2manycars]

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Originally Posted by Tom Wesenberg

I've never trimmed a rubber pad for the motor mounts, and I've only needed to spread the frame on the first engine I installed. If the steel sleeves are hard to push into the rubber holes, give them a shot of WD-40 or Vaseline.

I like to use silicone dielectric grease, as it does not attack the rubber as petrolium grease might.

[Purdy Swoft]

Originally Posted by 1930-Pickup

Purdy-

I'm glad you said that about not trimming the lower leg of the 'L' rubber pad.
I don't like the idea of trimming it off for the same reason that you cited.

I had to put some spacers under the mounts for the brake cross shaft to keep it from hitting the radius rods. The good news is there appears to be little effect on braking by adding those spacers, although I sure didn't want to do it. It's a temporary measure, besides, the brakes have several other issues as well. Yes, a full blown brake job is on the radar, but the brakes are still working reasonably well...for now.

Why did you not use a frame spreader for the last two pad replacement jobs?

How did you thin those pads? Did you use a belt sander? I assume you removed the three nubs for the frame holes as well then?

The metal spacers that you used under the rear mounts shouldn't cause any problem . When the service brake cross shaft rubs against the rear radius rods , it tries to lift the transmission and engine . The farther and harder the pedal is depressed the worse the problem will be . I don't mean to harp on brake adjustment and brake rod rod setup . I believe that It can make a big difference in this case. If the pedal doesn't have to be pressed as far it probably won't cause the problem that you are having . It will make a big difference in the brakes as well . If the brake lining isn't worn to the point that you get metal to metal contact an adjustment and removing the slack from the brake rods will serve more than one purpose .

I did use my frame spreader . Ijust didn't need to spread as far after thinning the pads . I didn't remove the three nubs . I used my D.A. sander set on single action to thin the pads . There is no real accuracy in sanding rubber pads but it did serve the purpose .

It probably isn't as bad as you may think . I believe that you can kill two birds with one stone . with a few adjustments and it won't cost anything to try . It may even be fun . Good luck you will probably be surprised

[1930-Pickup]

Originally Posted by Purdy Swoft

The metal spacers that you used under the rear mounts shouldn't cause any problem . When the service brake cross shaft rubs against the rear radius rods , it tries to lift the transmission and engine . The farther and harder the pedal is depressed the worse the problem will be . I don't mean to harp on brake adjustment and brake rod rod setup . I believe that It can make a big difference in this case. If the pedal doesn't have to be pressed as far it probably won't cause the problem that you are having . It will make a big difference in the brakes as well . If the brake lining isn't worn to the point that you get metal to metal contact an adjustment and removing the slack from the brake rods will serve more than one purpose .

I did use my frame spreader . Ijust didn't need to spread as far after thinning the pads . I didn't remove the three nubs . I used my D.A. sander set on single action to thin the pads . There is no real accuracy in sanding rubber pads but it did serve the purpose .

It probably isn't as bad as you may think . I believe that you can kill two birds with one stone . with a few adjustments and it won't cost anything to try . It may even be fun . Good luck you will probably be surprised

Thanks Purdy. I'm not too concerned about the brakes because they are working. They are toast though: rivet heads cutting grooves into the drums. I'm going to leave this dog alone for today, and tommorow, and probably several weeks.

My bigger concern for right now is getting the motor mounts back in. At this stage I have the steel mounts bolted to the bell housing and the mounts are just sitting on the frame (no rubber in place yet). This is a safe 'at-rest' position for the engine until the next step is figured out.

As it sits right now the steel motor mounts are almost touching each side of the frame. There is barely enough room for one pad on one side only.

The old rubber pads are very hard and thin, or just plain gone. It looks like someone replaced them a long time ago. If they were fairly thin when they were replaced years ago, and then the cab front mounting bolts were tightened, it may explain why the frame is too narrow right now.

I'm thinking of loosening the front cab mounting bolts and then placing a pry bar between the steel motor mounts and the frame, and pushing them apart some. Thoughts

[Purdy Swoft]

You will really need to loosen the front cab bolts, maybe even the carrage bolts at the rear of cowl . Though it may work , I've never tried prising the rear mounts for clearance . Before I got my frame spreader I used a 4 ton porta power jack to spread the frame .

[Tom Wesenberg]

I only install the rubber pads, then the motor mounts, then set the engine in place.
It would be really tough to do the rubber pads when you have to fight the mounts.