listnner

Was looking at semi solid engine mounts (65 -75 shores) for 2008 car, but my tuner has discouraged. Says it can trigger knock sensors and pull timing.
65 shores would be the softest of semi-solids and I thought knock sensors would only trigger with the stiffer semi solids or solid mounts ?

lflouie

Have you considered the Function First modified oem mounts? They use the stock mount but have the internal rubber voids filled with silicone, thus reducing the flex but minimizing nvh and potential interference with sensors.

listnner

Thanks, did not think of those. Have you got them and how do you find them ?

lflouie

Google FUNCTION FIRST or sometimes they list items on eBay...I got them directly from FF.

Yes, I have the basic FF stage 1 upgraded oem engine mounts on my 997.1tt 6spd. They do a very nice job of controlling engine movement, providing a "bolted down" feeling to the drive train and without any noticeable increase in nvh....perfect for my spirited street use. Having ridden in a friend's 997tt with semi- solid mounts, I didn't like the excessive nvh. It might have felt slightly tighter at 9/10s but for anything other than track or autox, they were simply unnecessarily harsh, IMO.

Bc my 14k MI 13 yr old car was still on original mounts, I also decided to replace the entire factory transmission mount adding FF stage 1 inserts. They make 2 stiffness levels, I chose the softest "stage 1" versions and it works great.

Adding the FF stage 1 engine mounts and transmission inserts along with a new oem trans/mount, made a big difference in the car....drives better, handles better, shifts better, seems to respond better....highly recommend.

TOTAL cost for all the parts was $800.

Jaskfri

Lflouie--Thanks for the information. I have been tempted to do this to my 49k almost 12 year old car and was concerned about NVH.

Skwerl

I think the knock sensor stuff applies to solids or maybe the hardest setting Rennline adjustables. My first mod was some Wevo semi-solids (same as RSS I believe), I highly recommend them. I've heard they wear out but I have 3 years on mine and they're still tight. It's a relatively cheap and easy mod that noticeably tightened up the rear. My originals were pretty old so they were probably due anyway. They did add a little NVH, but in a good way that I'd characterize as "rawness" - I'll never understand the people who want these cars to be luxury cocoons.

Also recommend the FF transmission mount insert.

ky13

What is the durometer rating of the Wevo mounts?

lflouie

When I was doing my research on semi-solid motor mounts one of the issues was that some of the aftmkt mounts, don't remember which ones, had a much smaller surface area where the mount seats to the frame vs stock. Some people reported issues with their particular mounts....so, I chose the FF modified design.

listnner

Fantastic, thanks for sharing lflouie. I had been looking at the FF gearbox insert. I think they are more forgiving than the Powerflex inserts.
I figured if you reduce play at the engine mounts, then the factory gearbox mount will be subject to more forces, so would need upgrading.
What sort of power are you running ?
I am keen to stiffen the drivetrain up a bit.
But my tuner reckons if your running higher power, then pushing the motor harder relative to stock and also stiffening the mounts will send the knock sensor past a threshold and cause it to trip.
Any truth to it or just a myth ?

lflouie

No idea regarding truth or myth relative to knock sensors....but I've read the comment numerous times.

I'm completely stock on the power train, but I'm OCD when comes to having a car well maintained and as fresh and perfect as possible....hence upgrading mounts due purely to age of car.

I

ky13

Also OCD in that regard. My car has 86k miles, so upgrading mounts/bushings is my first priority (I'm running 85A engine/trans mounts fwiw).

I think the knock sensor issue is a myth with regard to poly mounts.

nzskater

I have these installed with the medium bushings and don’t experience any knock issues. https://www.rennline.com/Rennline-Tu...oductinfo/M18/

listnner

Looking for real world experiences, thanks nzskater. Is your car tuned ? I think rennline mediums are 85 shores

lflouie

https://www.6speedonline.com/forums/...art-nos-2.html

Here is another solution using a Porsche part. The 964 RS motor mount is claimed to offer an noticeable upgrade and the users claim virtually no NVH differences except maybe at idle...after that no change. FYI.

ky13

That's correct. 75A/85A/95A (yellow/blue/red, respectively)