Motor Mount Issues

[Wild Bill]

Looking for opinions......

Are the front engine mount tabs necessary???

My 2001 502 bike broke the front motor mount TABS that are welded to the frame and bolt to the front of the aluminum heads. This happened several years back. I had the tabs welded back onto the frame back then.

I have my bike apart now doing some maintenance and I see that the front engine mount tabs are fine, but the bolts that go through these tabs are now both snapped and broken off inside of the heads.

These mounts can't be carrying any real weight, right? Do these tabs/motor mounts have enough of a purpose to go through the considerable hassle of drilling-out both of these bolts, etc.?

Thanks!

Bill

[Elvis]

If there was no stress, the bolts would not break.
V8 Choppers don't use them.
So there are two answers on two different style bikes.
Would the Choppers break them if they had them? Or does the frame have more room to sway and not break anything. Like a tree, or skyscraper, bending to a storm or earthquake.

[Ron Radulski]

Looking for opinions......

Are the front engine mount tabs necessary???

My 2001 502 bike broke the front motor mount TABS that bolt to the front of the aluminum heads. This happened several years back. I had the tabs welded back onto the frame back then.

I have my bike apart now doing some maintenance and I see that the front engine mount tabs are fine, but the bolts that go through these tabs are now both snapped and broken off inside of the heads.

These mounts can't be carrying any real weight, right? Do they have enough of a purpose to go through the considerable hassle of drilling-out both of these bolts, etc.?

Thanks!

Bill

Bill, I would ask Marv at Chopper City in MN,

[CanuckHoss]

Bill...both of my bolts have come loose at different times on my 502 trike...never broke.

BUT...when I took the heads to my head guy a couple weeks ago he said that it looked to him like the heads had moved or were moving on the block. When my techs took the heads off they said the bolts were all over the place as far as how tight they were..not torqued properly from GM?? Not sure.

Here is my thoughts on this..if the head bolts were not tight enough and the bolts in the frame held them and then if the motor was moving ever so slightly then that is where the friction / /movement on the heads to block would be..just trying to figure it out...

[502wingman]

The left bolt on my 502 broke a couple of years ago due to lousy factory design (the hole in the plate was not in line with the hole in the motor) We welded a new plate and its been good since. In my opinion the 502 is a heavy motor with a lot of torque and you dont want it be able to shift within the frame. Just my 2cts.

[Sonny]

My right side motor mount bolt broke a couple of years ago. I was able to extract it and see that it was just a regular bolt so I got a grade 8 bolt and carefully shimmed it up with the motor mount bracket so it fit perfectly and it's been fine ever since.

[craig haymaker]

I'm not much of a motor head, as compared to the majority here ! I had to replace a broken upper right motor mount last summer.
The head is not a good place to attach the motor to the frame, I don't think. As already mentioned, the right hand torque under power, and the left hand movement under decal raises hell on these upper supports. And how about an aggressive cam's loping shake while at idle ! The farther away from the crankshaft = greater side movement I would think !
Stan @ V8 Choppers did his homework when he did not use the upper portion of the engine to tie solidly to the frame ! I'd be willing to bet that the non-cammed engines have much less upper mount issues.
Craig H.

[Imzz4]

Wild Bill, Here's my 2 cents. Yes you need those mounts. I agree the heads aren't the best place to create an attachment to the frame. And the mounts using the intake manifold bolts brought their own problems with the expansion and contraction cycles . Besides the early aluminum brackets prone to breaking , it was a source of coolant leaks at the front.
Without using a mid-plate like the V8 frame uses, the two 1/2" bolts at the bottom of the frame and the two transmission bolts aren't capable of holding the engine torque forces by themselves. (especially in your case when the most you have gotten from a rear tire is 1200 mi according to your uncle! ) kidding.. Your mounts also add triangulation to the frame, and again without them, its a long way up and over and back to where its fastened. With the tubing being .095" wall vs. at least .125", do what ever it takes to make them work with the best fasteners and so there is no misalignment or side loading. I prefer using studs in aluminum , over bolts . If you can improve the mounts and pick up more than one hole in the head ,do that too. Studs through a plate with a spacer is a good setup but the problem is the lack of room . Good luck, you'll come up with something !