Dropping Front Diff for Motor Mounts

[wildphil]

I can't answer about installing stock mounts while the engine is still in the truck. I have only removed stockers and gone back with 2 types of solid mounts. I am sure what Dave has posted is what needs to be done. He has been working on these trucks for many years and has done about any work on them that can be done. I have placed new rubber mounts when installing a engine in a truck but will never use them again.

I know deciding what mounts to go with is hard. With Dave having issues with the JSM mounts that is not good news to hear about a product. And I don't even know if they are still available to be purchased. Sportsmachines sells a set of solid mounts and they are sold with the required replacement frame pads. I know nothing about these at all I have never heard reports about their use. Then we have the JTR option. To me they look like they could be a good viable option for the issue. Rubber to help cut down on vibration and the design looks like it will continue to hold even if the rubber tears for any reason. They will take a good bit of work to install.

I would never install a stock type mount unless I had the engine strapped down with a chain. But I don't like the looks of using a chain to hold the engine, so that is not likely to happen.

I believe for me I would still try the JSM mount on driver side with stock on the other. I may have the area beefed up at the weld. And also check to make sure there is no binding. I did not have this issue on the one that I installed. Actually the one that I used fit exactly like it needed to. And I thought pretty easy to install. But we all know parts are not always how they need to be and they don't always install very easily at all.

 

[1blkc4]

Its been a while I didnt notice any height issues on the mount I did drill out the JRT mounts and went too a grade 8 bolt I cant remember the size .

 

[corsair231]

Well, I finished the mount. Has to have been one of the most aggravating things I have ever done. This thing has become my least favorite vehicle to wrench on. I didn't drop the diff but I sure dropped the bolts. A lot. With this things ability to eat anything dropped I literally spent hours on search and rescue detail. This was such a hassle that I am considering getting a couple of for sale signs to keep in my toolbox in case the truck ever needs the mount replaced again.

 

[proptop]

Yep every time I walk in the shop to work on mine (as soon as I hit the door) take a knife and cut my hand because not only are you going to be Pissed you will be bleeding too. Keep up the good fight.
Bob

 

[corsair231]

Yep every time I walk in the shop to work on mine (as soon as I hit the door) take a knife and cut my hand because not only are you going to be Pissed you will be bleeding too. Keep up the good fight.
Bob

Yep, I'm beat up, bruised, and bloody. This thing is vicious.

 

[wildphil]

I am going to have to agree with all of the things that the two of you are describing about those darn trucks.

 

[DaveP's Ghost]

Next time raise the body off the frame the way the Factory Service Manual and guys like me that have been working on SyTy for over 20 years tell you to. You will be AMAZED at how much easier the mount R&R is, and how much less time the overall job takes, including the hour or so to raise and lower the body.

Glad you got it done. But you did it the hard way. (Not raising the body.)

 

[RealFastV6]

I believe for me I would still try the JSM mount on driver side with stock on the other. I may have the area beefed up at the weld. And also check to make sure there is no binding. I did not have this issue on the one that I installed. Actually the one that I used fit exactly like it needed to. And I thought pretty easy to install. But we all know parts are not always how they need to be and they don't always install very easily at all.

There is zero chance I’d install that JSM mount as-is.

At the least I’d grind it out and Tig weld it. I also see what Dave is talking about with the “M”. That small bridge between the “M” and the bolt ends up carrying all the load.

I have no idea why he slit it and mig welded it. A good bend alone would have had been stronger.

If I had either of my trucks apart I’d just make one.

 

[wildphil]

There is zero chance I’d install that JSM mount as-is.

At the least I’d grind it out and Tig weld it. I also see what Dave is talking about with the “M”. That small bridge between the “M” and the bolt ends up carrying all the load.

I have no idea why he slit it and mig welded it. A good bend alone would have had been stronger.

If I had either of my trucks apart I’d just make one.

Are you referring to the sides welded to the flat surface bolted to the block as the area of the slit? If so I would think that was done because it would because welding a mount would most likely be the only way for most people to make a mount. I would guess that it would take a specialized type machine to bend metal that thick but I don't know about that sort of thing. But you are right a bend would be much stronger.

Any a good weld should hold easily. I have many parts that Jeff has made. And every one of them have been welded. I am sure that something was wrong and some of the mounts he made broke. I see the picture Dave posted and Dave also said it happened so I know it did. I also know Jeff makes good parts but everyone makes mistakes. I would try to make sure that it checked out good. But I would use his mounts over any other that I have ever used and I have used all of them on SyTy's with the exemption of the JTR. But I would try the JTR mounts If I were to remove the engine from the truck. I believe they will work well but take a lot of work.

 

[RealFastV6]

When you slit the back of something like that, bend it over with a hammer, and then mig weld the inside corner, you've created three major stress risers. The first one is the slit on the back of the "bend." The second and third are on each of the toes of the weld. It's kind-of inevitable with a mig welder on a part like this. If the design of (whatever it is) is such that you're not stressing those areas then it doesn't much matter, but if you think about those tabs on a motor mount then it's a major problem. There's so much vibration and torque going directly into those stress risers that they're bound to tear.

See how Dave's pic of the mount after it was tig welded (post #15) the weld looks like a U shape rather than a dome? The edges flow into the part rather than creating a V shape where they join. THAT is what the welds (if you had to weld it) should have looked like in the first place, but still better to just bend it.

It's not a ding on Jeff, I've bought parts from him that have been fine, it's just the nature of such a small niche community where there's a lot of "I built one, I I had somebody install it on their truck, nothing catastrophic happened, and so I made a dozen of them to sell."

 

[wildphil]

I did not look the part over to see how it was constructed. But I don't know why anyone would slit a piece of metal bend it over with a hammer and the weld it. That would be a lot of wasted and needless work for no gain.

I would guess if that after the dimensions were found that the one flat piece would be cut then the two pieces cut and then all three pieces welded together. But those may not have been done that way. I never looked at them closely enough to see.

Looks like it was welded and the machine was not set on the correct setting to me. It should have held for what it was made for easily if welded properly. The only issue that I can see with having any solid mounts if they did not have an issue like the one in the picture Dave posted would be possible vibration. Like say if it had solids on both sides without that rubber cushion of stock mounts. I think they may crack over time. I am only guessing that is a possibility of course.