Well, just had a set of Prothane poly motor mounts installed, and the biggest thing I noticed was just how still the engine is now... my lord, I knew my engine was rockin and rollin before, but I guess I got used to it. I kid you not, the engine is literally as still as it was stock, only with the lumpity-lump of my cam instead of the stock sound. You can also tell a big difference with the mounts while driving... the front end of the car feels 100% tighter than it did before. I'm sure I can feel a greater difference with how tight the front end feels with the motor mounts than I did with any of my previous front end suspension/chassis mods.

Also, my exhaust is now stock still and isn't bouncing all over the place because of engine movement... they used to bounce up and down a great deal, and the y-pipe used to slap on the underside of the car every once in a while. Also, my shifter used to bounce around too, and now that is stock still (just some vibration in it instead of actual movement) None of those things happen anymore... also all of the dash/trim rattles I was developing after my cam install are all gone now.

At this point I would definitely recommend doing motor mounts to anyone with a lumpy cam... and I'd also recommend the poly transmission mount for M6 cars as well. I now have driver's and passenger's side poly motor mounts, plus the poly trans mount, and everything is extremely tight... much better than before.

 

Is there a vibration in the car now. I am swaping motor in the spring and was looking in to this myself.

 

Its an awesome improvement, isn't it? Its amazing how much slop is in those factory mounts.

 

It is an awesome improvement... easily one of the best seat-of-the-pants suspension mods I've made. I knew the motor mounts would make a difference, but I didn't think it would make as big a difference as it has.

There is a little more vibration in things like the pedals and in the shifter, but overall the car itself is MUCH quieter... no y-pipe banging, no heavy rolling motion in the front end from the engine bouncing around, the shifter doesn't rattle around anymore like it used to, the dash doesn't rattle anymore like it used to... so even though there's a little more vibration in the pedals and shifter, the tightness from the mounts more than makes up for it by quieting down other areas of the car.

 

thanks for the info.

 

I agree, great mod.

What I noticed was the CAR shaking, not the motor and interior anymore. Noticeable when looking in the mirrors.

 

interesting, im doing a motor swap soon and i'm interested in this.......where can i get a pair of mounts for a good price?

 

Thunder Racing

 

Do they install like the Energy Suspension pieces? Meaning, they reuse the existing stock clamshell or do they come as a complete bolt-in assembly?

 

I got my Prothane mounts from Thunder Racing... they do re-use the stock clamshell, which is an SOB. The Prothane mounts are significantly bigger than the stockers, so the clamshell doesn't want to fit too well with them.

 

Does the car shake alot more than before?

Thanks!

 

If you have a lumpy cam in the car now then, yes, you will get a bit more shaking of the whole car where before only the engine/trans shook like crazy. However, that is not to imply that you are going to see any significant increase in chassis vibration, etc. I had virtually no increase in vibration while driving with the poly mounts.

Overall (again, assuming a lumpy cam), the car will idle smoother than before based on my experience. Basically, the shaking of the engine was isolated from the chassis before, so the chassis did not shake as much while the engine shook a lot at idle. Now the engine is not as isolated, so there more shaking transmitted to the chassis - however, you now have more dampening so overall it feels better.

 

well said... I think overall there's more shaking in the car itself (although you don't notice anything shaking in the cabin), and I do have a little vibration coming through the pedals and shifter, but nothing bad at all. Overall the engine doesn't feel like it has a life of it's own, and it's much quieter since the exhaust and transmission aren't being rattled around anymore.

 

I had a poly trans mount in a while ago and hated it, put the stock rubber back on...

I'd like the try the motor mounts though, was the install tough? was your motor out when you did it, or just raised and supported?

 

What kind of poly trans mount did you have? I know people have had trouble with the Energy Suspension one... I'm not getting any more vibration from my Prothane one than I did before. I already had some because of the Pro 5.0 shifter I have.

The motor was just raised and supported... which made it a lot tougher than if you had the motor out of the car.

 

The poly mount installation can be a bit of a PITA if you're doing it with the engine in the car. The key IMO is to be patient. Here's a link to some instructions I wrote up a while back that may be useful - https://ls1tech.com/forums/generation-iii-external-engine/52884-tips-instructions-replacing-driver-s-side-motor-mount.html

With regard to vibration, my installation process and experience was as follows:

1) Installed only the Prothane driver's side poly engine mount. Test drive. Noticeable decrease in engine shaking, noticeable decrease in Y-pipe banging - still banging during hard shifts (I had very tight exhaust clearance at the time).

2) Installed Prothane passenger side poly engine mount. Test drive. Very little change from (1) above.

3) Installed Prothane trans mount (M6). Test drive. Further decrease in Y-pipe banging. Slight increase in chassis vibration.

HTH

 

I used the ES trans mount...I later bought a Prothane mount with the intention of using it, but instead went back to the stock rubber one...maybe I'll try it again this winter since you say it's better.

 

I put in the spohn a couple weeks ago. Just did one side. With a cam it is great. I use to keep my idle higher than it needed to keep the car from shaking like crazy at stoplights. Now I'm getting idle speed down and it doesn't shake. There's a bit more minor sharp vibrations. I like it much more than the tranny mount.

BTW, anyone looking for just one, shoot me a PM. I have the passenger side available.