Ive searched around and it seems that everyone only does this mod to the front and rear mounts. Is there any benefit to doing this in the tranny and side mounts?

 

might as well. im guessing it will give you lateral siffness and possibly a slight increase in power transfer with the poly tranny mount. less engine movement?? but the engine mainly moves in the front to back motion...

 

I'm thinking it might add some vibration and probably won't do much. I can unbolt my tranny mount and the tranny does not sag. Apparently that mount supports little to no weight...

 

ya the tranny mount doesnt do much when the car is at a stand still but what about under hard acceleration...does the tranny mount then help stop the engine from rotating?

 

certainly possible...

i know this isn't quite the same, but here's an idea:

when you rev the engine, you can see it rotate a bit front to back.
rev the engine with one or both of the side mounts removed and see if there is a larger amount of movement this way.

it might at least give an idea of what happens under load...right?

 

I've seen cracked 4th gen tranny mounts... So putting poly in there will do something... dunno what tho.
Dr J

 

Polyurethane engine mounts stop the motor from rocking, which may aid in preventing or stopping wheel hop. They can also help put less strain on the transmission mounts if your stock ones are worn. Down side to any polyurethane mount is they will result in increased vibration. I have polyurethane transmission mounts, and it improved the shifter feel, it may help in preventing missed shifts? Do some research on google.

 

have the ES front and rear mounts and was wondering the same. the front and rear mounts keep most of the movement to a minimum.(torque mounts) i think poly tranny and side mount will only be good for more vibration. ill be getting factory tranny and side mount if anything.... .02

 

I was curious about this. I have the front and rear mounts that just need to be installed, but wonder about the other 2. I think they also help keep the motor/tranny from tilting.

S

 

I'm jealous of everyone here with all of your poly mounts. I'd do it in a heart beat if there wasn't problem...

Sometime in the past, a dumb$hit mechanic obviously replaced a motor mount. When he put the crossmember back on, he cross threaded one of the two bolts in the rear. the threads are F***'d. What do I do? Helicoil? Drill and tap it? I know if I take it out one more time, it's not going back in. Heck its barely in there as it is...

 

Why curious? Pop the hood of as many 4th gens as you can, take a look at the side mounts... if they're cracked, then u kno poly will help. I've seen quite a number of busted tranny mounts. They're in stock at many parts stores, which probably means they're in demand cuz they do break.
Dr J

 

Buuuuuut what if they're cracked because they're dry rotted...you know, just really old rubber that's cracking. That wouldn't indicate lots of stress necessarily.

 

Yes it helps. the engine not only rocks front and back but it also twists. The vibration is the same as just doing the cross member mounts. Also, this is a moot point. If you are going to polyurethane the bottom mounts than you have enough to do the tranny and side mount too.

 

I left out some information. Even the ones with I've seen with poly front/rear mounts have had their sides deteriorate to some degree after installing the front/rear. Assuming the sides don't handle any stress, implying the front/rear do all the work, then dried out sides would just dry out, but remain in place in dried condition. Motion from the body or engine causes them to fatigue and fail quicker.

Dr J

 

I have poly front and rear but kept stock left and right. I only have a little increase in vibration. The front and rear take all the beating, the left and right do little.

 

OK so we've established that the side mounts aren't worthless. They might control movement a little bit. Still, IMO, the vibration added will outweigh the slight amount of movement reduced by adding poly side mounts.

keep stock side mounts, enjoy vibration free cabin.

 

im probly going to do the poly urethane to the side/tranny mounts. I looked at my tranny mount and theres basically no rubber inside it that is still connected. But i do agree that the rear and front mounts take the most beating and with what you say.

 

I don't even feel the vibration with poly filled. I don't understand how the sides would add more. Basic physics. The engine just doesn't go back and forth it twists. Therefore the side mounts are there not only for support but for stability as well.

 

we know, its just a matter of how much and if poly filled side mounts are worth it.

 

Weld some solid plates and be done with it.
Dr J

 

new factory side mounts FTW !!!!!!!!!!!!!!!!!!! the added vibration from the poly side mounts wont justify theyre need.get poly front and rears and be done with it.........

 

<--Yep , spoke to the guy at E.S and they said the same.
For a 5th gen anyway. And youll get over the vibration once your launching a few rpm higher than you could before with NO wheel hop.

 

hate to bump the thread for this...but it is related to doing poly mounts.

I can't take the lower crossmember off without having a plan to fix the threads before it goes back on. I'm thinking I'll just helicoil it and that way I can still use the factory bolt. Anyone know the bolt size / thread pitch of the four bolts that hold on the crossmember?