914Driver
914Driver MegaDork
12/17/16 9:57 a.m.

This got me thinking...

Not always a good thing. I'm putting a 350 with a TH-350 tranny in an '83 Benz, it would be simpler to just fab solid engine mounts than mess around trying to fiddle in some rubber ones.

If you run solid motor mounts, do you also need to use a solid tranny mount?

With solid mounts, what's the draw back? Uncomfortable, vibration, break parts?

Thanks, Dan

bentwrench
bentwrench Dork
12/17/16 10:06 a.m.

By using solid mounts any body flex will be transmitted to the motor/trans combo. Aluminum transmission parts may fail (tailshaft or bell housing)

I also don't believe it is a good practice to mix solid and rubber mounting. You can't have one end flexible and the other solid.

Stock GM trans mounts seem firm enough, and Energy Suspension bushings work well on the motor. I'd look at their 19607.

Dusterbd13
Dusterbd13 PowerDork
12/17/16 11:11 a.m.

I was told that you don't want all 3 to be solid, as it will break stuff. Look for my critique my motor mounts thread. We discussed this a lot. It was in October or so.

Dusterbd13
Dusterbd13 PowerDork
12/17/16 11:12 a.m.

https://grassrootsmotorsports.com/forum/grm/please-critique-my-solid-motor-mounts-i-made/122905/page1/

Billy_Bottle_Caps
Billy_Bottle_Caps Dork
12/17/16 12:10 p.m.

fixed that for you

custom solid mounts

BrokenYugo
BrokenYugo MegaDork
12/17/16 12:51 p.m.

All I know about solid mounting an engine does not go well with a luxury sedan, even in a full blown race car the benefits are often minimal.

Crackers
Crackers Reader
12/17/16 1:09 p.m.

No reason not to use a rubber trans mount. Especially for a THM350. The mount is stupid simple and easy to fab brackets etc for.

Had this setup in an Impala long enough to burn up 2 transmissions without breaking anything.

GTXVette
GTXVette Reader
12/17/16 1:36 p.m.

at least a rubber tailshaft mount. too much Flex in streetable cars and we even would use a poly in the rear for the Late model and they don't flex much.

Dusterbd13
Dusterbd13 PowerDork
12/17/16 7:34 p.m.

In reply to Billy_Bottle_Caps:

Thanks!

TheV8Kid
TheV8Kid Reader
12/17/16 9:19 p.m.

We've done solid engine mounts and stock rubber transmission tail mounts on many many cars and never had an issue.

bearmtnmartin
bearmtnmartin GRM+ Memberand Dork
12/18/16 9:12 a.m.

My race car has four seasons now on solid mounts. I worried about stress cracks but i have had no issues. And in the meantime I have seen a few other cars have issues during impacts with rubber mounts flexing enough to take out distributors, radiators and half shafts. Pretty small sample group but I have no reason yet to change back.

Huckleberry
Huckleberry MegaDork
12/18/16 10:00 a.m.

I have run solid engine/trans/diff mounts in a fully caged partial tube chassis E30 race car that was used for 35 minute sprint racing - balls out, no compromises... and needed to put eyes and wrench on it after every use.

When that same car started doing 4, 18 and 24 hr races we started cracking things and breaking or losing bolts. Once we swapped to nylon that all stopped but the performance was practically the same. There was no acceleration losses or "wind-up" at all. Just less vibration.

So, after that experience I am in the "never" category for solid powertrain unless its home-made for a budget build (and the aluminum is free) and it's auto-x or something where sustained vibration isn't an issue. Otherwise I'm buying or fabricating in a hard but not solid material.

For subframe and other suspension parts - I'm all about solid aluminum or monoball though. No give is the right amount for anything that determines tire placement or steering angles front or rear.

GameboyRMH
GameboyRMH GRM+ Memberand MegaDork
12/19/16 2:29 p.m.

+1 for what Huckleberry said. All-metal engine mounts turn a car into a paint shaker with wheels, the vibration will rattle your teeth loose from your skull and your nuts loose from your...bolts. All the bolts on the car (seriously).

trucke
trucke Dork
12/19/16 2:37 p.m.

I put solid motor mounts on my first car, a '71 Nova with a 307ci V8. It was cool. The whole chassis would flex when you revved the engine. Very stupid, but cool for a 17 year old. Did I mention it was stupid?

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