cutlass476

Anybody install these? How do they compare to Wevo and stock mounts?

nwGTS

Short Answer:
Nearly identical. Both use poly inserts. If you track the car at all these will have a very noticeable difference in preload and shifting (they did for me). A DD car you might notice but not really.

Long Answer:
There are three (basically) types of engine mounts.

OEM
Semi Solid
Solid

Too cold:
OEM use rubber 'grandpa's knee joint' bushings that will flex a lot so the dentists who bought our cars new have very little NVH that could upset their frail bodies. The downside is that there is preload and weight transfer with the mounts and engine respectively as well as gear shifting issues when the engine/tranny alignment is off from weight transfer load.

Too hot:
Solid engine mounts limit that engine load transfer almost completely. While the fillings will not shake out of our dentist's head, his glasses may be askew from time to time. Also, vibration from the solid engine mounts has been known to trip the knock sensor and put the car into limp mode. Not good. Rennline's solid mounts drop the engine about 8-10mm.

Just right:
Semi Solid mounts trade the wet noodle inserts of the OEM mount for a polyurethane insert along with some weight savings (maybe a pound). The Rennline mounts also drop the engine 8-10mm (not sure about the Wevo) and also come with three different sets of poly bushings (street, sport and race) so you can 'tune' it the way you like it. They, arguably, are the perfect balance between OEM mount preload-you-could-time-on-sundial and Solid mount NVH overload (not to mention potential knock sensor tripping).

I know of little difference between the Wevo mounts and the Rennline at the time I did my research (July 2015).

IMO, I think Wevo has been more popular simply because they were in the market first and have been adopted by more race shops. Marketing won for them.

motopix

I know this isn't the question you asked but my impression of the installed Wevo's was that they set my old, high mileage cabin to buzzing at some resonant frequency somewhere between 3-4k rpms.

And you can call me crazy but the car seemed slower with the semi-solids. Hell, I thought I was crazy. But my new mechanic mentioned this as a possibility before I said anything about it. His explanation was as nwGTS said above regarding the solid mounts, the knock sensor can get triggered.

If you want Wevos, send me a PM. I'm pulling them off with a couple of hundred miles on them.

Psymon

I switched from the OEM engine mount to the Rennline solid mount about 6 months ago.

Performance-wise I haven't noticed much different, either DD or on the track. But I really like the additional sound and it's "raw-ness". The additional NVH isn't an issue for me at all. It's been 6 months now and both my wife and my 8-year old son still hasn't said anything about it!

I was also worried about the possible issue with the knock sensor but so far so good.

I have not experience with the Wevo, but I'm glad that I skipped the semi and went straight to solid.

Hella-Buggin'

Interesting, this has been on my list of mods but this is the first I've read about the knock sensor issue.

Louis de Funes

I have a set from RSS Semi Solid which I purchased from Sharkwerks. I have them in the car since August 27th and like them. I do not hear any noise nor do I feel that this has slowed my car down in any way.

Petza914

+1

I changed my OEM mounts for the RSS versions at 40k miles. Better controls the engine through turns and over wallowing bumps. I can feel the difference and I don't track my car.

SapphireGT4

I understand OP already decided on OEM rubber engine mounts. I have Dundon street headers with their loud muffler on the car. My original engine mounts were sagging, evident by excessive gap between tail pipes and bumper. I replaced the mounts with Rennline semi-sold engine mounts and went with their blue (medium) inserts. There was a noticeable improvement of smoother idle and no noticeable increase in NHV - maybe even a slight reduction in NHV. But my mounts were shot and needing replacement. I then installed the Cantrell transmission mounts, street compound while doing 4.0 clutch/LWFW, 3.89 RP, and LSD. The car now has bit of drone between 2300 and 3000 rpm. Its annoying but in no way unbearable. I switch the Rennline motor mount inserts to soft (yellow) and made little to no difference. Just a heads up for anyone considering doing both SS engine and trans mounts.

Edit: I have 7.1GT3

smrpr

I hope so since it's been 9 years since this thread was created!

Frykman_991.1

..

fiddlesticks

Wow, glad I found this thread.

To confirm a couple of things, if I hear this buzzing around 3-4k RPM and one of my exhaust tips (the right side) is lower compared to the left, seems like my mounts need replacing then?

1.5 month old owner here and just noticed these two things recently while driving more spirited; was wondering what was going on.

waterpanda

can you elaborate on the buzzing sound? Hard to describe noise and feel over text I know, but the sagging of exhaust tips is a common symptom of old/worn engine mounts on 997s given the fact rubber gets old over time and the age of our cars, so definitely worth looking at if you don’t have history of it ever being replaced.

OwenGrey

I have the Function First Mounts and am very happy with them. My car is actually much smoother overall but I do notice a mild "buzz" around 3-4 K rpm. It's not unpleasant to me. It's just a bit more vibration from the engine but if you have a low tolerance for NVH then I'd go with stock mounts. I've also read concerns over knock etc. The FF mounts may be a less aggressive option than the Rennline's. I had 60k miles on the original mounts. Totally worth it.

fiddlesticks

Fair enough. Replacing then might be my next item then, the 8 year service record history I have does not note replacement.

The buzzing sound is, as far as I can tell, on the right side when I go to higher RPMs. It’s like a high pitched drone… almost as if something on the front is catching something in the air and then travels all the way back. Hard to articulate but that’s what I have got at the moment.