solid tranny mounts?

[ScotcH]

hey all,

My rear tranny mount, and likely my motor mounts are shot (I can rock the engine form side to side by hand).

Can you forsee problems if I replace all the motor mounts with OEM, and the tranny mount with a solid mount? The rear mount tends to go easily in the Legend, hence the solid idea.

I'd love to get poly, but I'm out of luck, unless I go custom. Also, will this affect PIPs in any way?

[ADAM]

i used a solid welded engine mount for 2 years in solo 1...then when i went turbo went back to stock mounts...now th engine hits the firewall under power..so i just welded my mounts solid again...

problems....

you get more vibration under idle and low speeds...could not really tell that much under higher RPM..

bonus...

more instant throttle response...

[ScotcH]

Thanks Adam. What about mixing solid with OEM (rubber)? Do you think the rubber ones would be overly stressed?

[ADAM]

i just welded the torque side of the engine mount (driver side only) using 1/4 plate steel...and layed some "beads of welding death" on them.... i "think" that just welding the one mount will hold the engine torque since its pretty hefty metal....the engine is solid...will see next season if just the one side welded will hold or not....if not i guess i will have to weld both sides like i had before..i only welded one side cause i am lazy and the other side was not easy to get too..and i did not feel like lifting the engine to pull the mounts out and weld them all...

[AirCooln]

I guess every car is different. Mini mounts should not be mixed. Either solid or OE. I have heard stories of mounts being pulled through the body where your feet rest.

[RacerRick]

On V8/RWD cars you never run full solid unless you are running front and rear motor plates and have very carefully gone over driveline angles.

You tend to break the tailshaft on the trans from engine torque. So you run solid engine mounts and a poly trans mount.

[ADAM]

hmmm thats interesting....on the 240sx my drive shaft is a 2 piece ...how would that effect this whole thing?

[RacerRick]

It seems to be the engine/transmission's (as a unit) torque reaction that does it.

Every car I have seen a broken transmission on had a once piece driveshaft so I can't say definately that a two piece driveshaft will make any difference. I would not assume it would since it would have no impact on how the engine torques up against load really.

On auto trans it seems to break the tailshaft, and on sticks, it seems the bellhousing is the first to go.

[Chris91GT]

Interesting...

Having just broken the front case on the Tremec 3550 in the Stang this is very interesting indeed.

Of the four "ears" where the tranny case is bolted to the bellhousing, both on passenger side were sheared off recently at Mosport. Pulled a large chuck of aluminum right out of the case... nasty mess.

At the time the car was full solid-mounted. And only a 4-pt rollbar on a notoriously flexible chassis. The car had just come back from Watkins Glen recently as well, where g-forces are exceptionally high.

My personal theory is that the front subframe and the chassis were flexing differently under the high loads at Watkins which stressed the tranny "ears". Mosport was just when it broke.

To rectify, we plan to complete the cage in the car, including tying in the front struts.

Now that you're mentioning this, I'm curious. If the car is theoretically solid with a complete cage and the engine and tranny are solid-mounted, should I expect a problem? I can't see there being one. Perhaps I should install a urethane mount just as a safety factor.

Or would that lead to stress if the engine is solid-mounted to a rigid chassis and the trans is not? Too many uncertainties!

[ScotcH]

Originally posted by Chris91GT
Perhaps I should install a urethane mount just as a safety factor.

Or would that lead to stress if the engine is solid-mounted to a rigid chassis and the trans is not? Too many uncertainties!

This is what I'm worried about ... granted, I'm only running 230 HP, and it is a FWD, but the engine and tranny do sit like in a RWD, just that the drive shafts run throught the front.

[RacerRick]

Th block on a 5L flexes alot when you really get on it and will try to twist up. This will also stress the trans. I think the chassis flex does impact the trans to a degree, but the engine torque reaction really seems to be what kills em.

The mustangs I saw with solid mounts broke the bell at the flange the engine bolts go through. I have heard of taking the ears off of older top loaders but never seen it myself on a T5. Usually I see them with a hole in the side from a gear blowing though the case! I have friends who drag stangs, but don't really know anyone who road races them.

[Dave]

Arek, no PIPs associated with engine mount changes, so you're golden there.

FYI, I have run a combination of poly mounts and OE mounts in my Civic with no ill effects. However, the poly rear main tranny mount does transfer a lot of vibration and noise through to the driver. If you want to keep your pimpmobile at maximum pimpage, I'd suggest you stick with the OE mounts.

One ghetto way to stiffen up OE mounts is to inject urethane in all the gaps, contours and grooves in the mount. You'll need to let it harden for about 24 hours though, so do this on a weekend when you can let the car sit. This really firms the mounts up a lot and doesn't seem to damage their longevity from what I've been told (I've never used this method myself, but a few guys in HADA have).

[DECH_92]

Originally posted by RacerRick
On V8/RWD cars you never run full solid unless you are running front and rear motor plates and have very carefully gone over driveline angles.

You tend to break the tailshaft on the trans from engine torque. So you run solid engine mounts and a poly trans mount.

Chris
Go with the solid engine and poly trans mount.
I have had no problems with this combination.
I dont`t even have sub frame connectors on.

[ScotcH]

Originally posted by Dave
Arek, no PIPs associated with engine mount changes, so you're golden there.

FYI, I have run a combination of poly mounts and OE mounts in my Civic with no ill effects. However, the poly rear main tranny mount does transfer a lot of vibration and noise through to the driver. If you want to keep your pimpmobile at maximum pimpage, I'd suggest you stick with the OE mounts.

One ghetto way to stiffen up OE mounts is to inject urethane in all the gaps, contours and grooves in the mount. You'll need to let it harden for about 24 hours though, so do this on a weekend when you can let the car sit. This really firms the mounts up a lot and doesn't seem to damage their longevity from what I've been told (I've never used this method myself, but a few guys in HADA have).

Thanks for the info, Dave. I will likely replace with OE, since I may have changed my mind about using the Legend next year on the track ... with the new paint and interior, I will be like new, and I really want to keep it that way.

[Dave]

time for a Civic track beater, eh?