L-body specific Front Mount Premature Wear

[jmgtp]

this may even belong in OT since it doesnt have much to do with the engine itself, well sorta it does...

1990 Beretta GT, 3.1/getrag

The front mount and lower trans mount are new. The rear mount looks good and the upper trans mount has been modified to be more solid than a stock unit. The front mount is about 3 months old and I notice its already starting to show signs of fatigue. I dont abuse the car much at all, it will see 5k rpm about once a day and I dont shift the trans hard at all. In neutral if I rev the engine I can see it pulling up and down on the mount (about 3/4" of total movement) and this slop can be felt during driving. Its annoying more than anything else. The mount is warranted for life but I dont want to have to replace them every couple months. Has anyone found a more permanent solution? I'd still like to get the bracket off a W body 3.1 and fabricate a 'dogbone' style mount to work using the upper radiator support. Granted the upper radiator support is kinda flimsy but it doesnt need to be all that strong for this purpose. Any other ideas/solutions out there?

On another note, the car shit the cat convereter the other day so I replaced that last night and the engine seems over all more happy, smoother and torquier and quieter (the cat that was in the car looked old school and was enormous! the new one is about half the length). And I had a blowout on the highway the other day, so decided it was time to replace the tires all around - ended up with 'General' something or other all seasons, theyre ok but they ride very hard!

[RidgeRunner]

Probably the same mount as teh J body... I put pieces of a cut up tire in my front mount to reinforce it, seems to help a little.

[jmgtp]

I did that too!! I stuffed all of the openings. Didnt seem to last too long though
Maybe next time I'll fill the openings with some polyurathane.

[Cliff8928]

I had filled mine with some black PL roofing sealant a few years ago, took forever to dry but i didn't know anything better to use at the time.. one of my next projects will be to fill all the mounts with urethane casting compound (94a) from www.mcmaster.com (McMaster Carr)

and yeah, those mounts do suck, especially with a 5-speed

Cliff Scott
89 BerettaGT
89 Volvo740

[Corpse]

I was thinking about this aswell. The mount is way too weak and, I've ripped up a few of them.

I was thinking, maybe take a hunk of metal with rounded edges, maybe almost a half inch thick and attach it to the top inside of the mount. That should be the side that takes all the torque, right?

That way the rubber wouldn't be allowed to stretch that far and, maybe hold together longer. It may be solidifying part of the mount but, I also don't believe there will be much of any added chassis vibrations, due to the fact there would still be all that rubber.

Any thoughts?

-Dave

[jmgtp]

It is the topside that takes the torque under acceleration, but you have to keep in mind when you let off the gas abruptly or decelerate from high rpm the forces are on the lower part of the mount. I think the bumpiness of the engine is a result of the mount moving in both directions when torque changes from the engine driving the wheels to the wheels driving the engine (accel to decel).

As for sticking pieces of metal in the mount... I think itd fall out eventually. I had bits of hard rubber jammed in all of the open spaces of the mount. I mean packed in there good and the rubber on rubber friction made it impossible to remove, even with pliers, so I felt that it would hold. Nope... 2 months later all the pieces are gone and the mount is wobbling all over the place. Now, I think if small steel keystock is used to fill the openings AND then fill the little gaps with polyurathane we may be on to something.

[Corpse]

Well, for the metal, I meant bonding it somehow to the other part of the mount. Sounds very logical that accel->decel and vice versa are hurting the mount. Perhaps both sides should be "braced"?

If they made solid mounts, I would get them, but, then again, it probably would cause a lot more wear in certain areas. So I say, make do with what you've got..

-Dave

[jmgtp]

Solid mounts would be easy. Theres the metal housing, the rubber bushing, and then the metal with the bolt holes. Just burn out half of the rubber and weld some keystock from the housing to the interior metal piece. Then burn out the other side and do the same. Reason I'd say only burn half out at a time is so you keep the piece that bolts to the engine in roughly the same place. I think itd be too harsh and depending on how well its welded/reinforced may break. For an all out drag car it might work but for a daily driver itd be too unyielding.

[Corpse]

That's not actually a bad idea. I mean, I understand also, that for normal usage it would probably be worthless. But, for competition usage, a solid mount would be prime. Especially with the L-Body having the weak front mount for the V6's..

I think I'll try something, I have a couple of spares I can modify. The ones on my engine are new so, i don't want to mess with them.