Schitzo

iTrader: (6)

I getting ready to mount the engine and trans in my 71.....I am wondering if should go with a poly trans mount or go rubber....my engine mounts are poly.

The poly trans mount does not allow much torque flex which I think would stress the bellhousing alittle more than rubber mount

I am leaning more towards a rubber mount...

my question is, what are you guys using and and for those who are done and driving.....what impression do you have with your setup.

thanks guys
Robert

jagwrjack

My new stock rubber trans mount separated within the first 300 miles.
Using a 'Summit' poly mount now. 3000 miles on it now.
I have an Rx7/Ls1 tho.

Schitzo

iTrader: (6)

thanks for the info....what motor mounts are you using?

MeentSS02

iTrader: (11)

The general consensus (with 98+ F-bods) seems to be that poly engine + poly trans mount = vibration city, but I haven't tried it myself. I have a rubber trans mount in with my poly motor mounts, and I really like it. Maybe I'll throw my old poly trans mount back in for grins.

Scooter70

iTrader: (1)

I have Energy Suspension poly motor and tranny mounts. NVH is not really a concern on my car though.

jagwrjack

I still have on the stock rubber motor mounts. I wanted no vibration.
Only went to the poly trans mount out of necessity.

MrDude_1

iTrader: (4)

i reccomend a poly mount for any fbody that is driven hard and still has the torque arm on the transmission tailshaft...

most vibration people complain about is NOT because of the mount, its because of bad driveshaft angles.
when they install the mount, it raises the tailshaft... but if you have saggy motor mounts, that can cause problems... it tilts the engine nose down... to "fix" this, alot of people run it without the preload plate...

White.Lightning

iTrader: (53)

Poly is the way to go. You won't feel any/much vibation from the chassis. More vibration occurs when you weld in a crossbrace for a torque arm or something along those lines. I put mine in and love it.

Andy

ss496

iTrader: (7)

make sure your mounts are all the same material or else you WILL break ****. the poly mounts are stiffer so it will vibrate more, but your engine/trans will not flex as much. the stock rubber will be smooth, and vibration resistant

MrDude_1

iTrader: (4)

meh, if you run a SOLID trans mount and rubber engine mounts, you risk cracking something from stress.

but there are literally 1000s of guys running poly trans mounts in fbodies with rubber engine mounts.
i personally have installed atleast 10 of them, and ive NEVER EVER even read online about someone cracking/breaking/badstuff because of it. however there have been alot of people who throw their driveshaft angles off (from saggy stock motor mounts), or do other things that cause vibration.

just remember that something has to cause vibration... find and fix the cause, dont just try to isolate whats vibrating. just because you change the trans mount, doesnt mean thats the problem.. it just means it showed you that there is a problem.
if you use that mindset, you'll be able to run one, no problem, never tear or replace one again, and your car wont vibrate.

MeentSS02

iTrader: (11)

MrDude...do you run poly motor and trans mounts? I'm tempted to try my poly trans mount again after my motor mount install...

MrDude_1

iTrader: (4)

ive run every combo of both.

my current car has had a poly trans mount for the last 3 years, and i have poly motor-mounts that i would LIKE to install this weekend.. although i dont see that happening (no free time....)

before the install, measure how high the motor is in the chassis, then measure again after the install.. id bet $$ that it moves up a good bit..

btw, after either mount change, check your pinion angle if you have an aftermarket torque arm that doesnt mount to the trans... sometimes there's a good bit of change.

slowscott

iTrader: (8)

I had a prothane trans mount in, but took it out due to it causing vibrations at certain rpms. I'm almost positive it was from improper driveshaft angle because it actually seemed to quiet my pro 5.0 rattles down. I still have the stock motor mounts.

MeentSS02

iTrader: (11)

Hmmmmmmmmm...screw it. I'm gonna give it a try and see what happens. No adjustable torque arm for me though...

MrDude_1

iTrader: (4)

you can semi-fix that in some cases by taking out the preload plate.. that lowers the height of the tailshaft some, and brings it back closer inline....


but the real solution is to raise the front of the engine/trans assembly back to where it belongs.