Not4off

This may add little to the discussion but will touch on my experience. Installed semi-solid engine mounts on my 2009 Porsche C2S with little left of the original interior aft of the leather dash including much of the sound deadening material. Did not notice a dramatic difference with the engine mount change. The car had already been stripped of its interior.

Not until two weeks later after installing semi-solid transmission mount INSERTS did I notice a big difference. First, the engine sounded (to my ears when seated behind the steering wheel) completely different! Had someone told me there had been an engine swap...I would have believed it. Outside the car...no difference. Even after months of track driving the engine sounds lower in the rev range than it is. In addition, I have more vibration noted principally in the rear view mirror image. For me that amounts to a "so what." Others may disagree.

On the other hand, grabbing a 2nd gear downshift under high lateral load does not seem appreciably easier with the changes which is somewhat disappointing. Of course my car has 94,000 miles now with a significant amount of track time. My car also has stiffer springs and sways.

I believe my car is pretty competent in stock form but wanted something with a harder edge and would suggest that the stiffer springs contribute the most in this regard. If nothing was done beyond the eng/trans mounts, that would have been a reasonable step as well... keeping in mind a bit more vibration which I didn't find objectionable.

Would always recommend driving (or riding) in a car modified in the manner you're considering first.

E-man930

I did

Tom M'Guinn

How did the two compare? Was the 80A louder with more vibration? Is that why you redid it?

E-man930

80A felt a bit too solid in my case so I remade another with 60A urethane putty. (Version that hardens in 15 min)

Tom M'Guinn

Well, I swapped out the mount a couple times for comparison. The factory mount by itself transmits way less vibration and gear noise than the semi-solid mount. For my car -- civil street car -- the semi-solid mount was just to loud. I ended up strengthening the end pieces on the factory mount by welding in reinforcement pieces to box them in, and then filling with 60 urethane. Here's a video trying to show the difference between the 60 and 80 hardness Urethane from McMaster. Not sure how much it comes through in the video, but the 60 is much softer. In the car, a 60-filled mount is "nearly" like a stock mount, but transmits just a smidge more noise and vibration. If the stock mount transmits 1 and the semi-solid transmits 10, I'd say the 60 harness urethane is about a 2 or 3. Assuming my CV joints survive, I think 60 is a good compromise and plan to keep it.

V2Rocket

Thanks for taking the time to do such a comparison, and sharing your thoughts.

I wholeheartedly encourage all 85.5+ 944 owners to do this mod.

Tom M'Guinn

I had ordered both the 60 and 80 before opting to try the semi-solid mount. It has a pretty short shelf-life though. By the time I decided the semi-solid was too loud, both cans of urethane were past their expiration date. So, I figured I'd check them out and order the one that seemed better. The 80 is nearly solid, so I opted to try the 60. So far, so good. Your instructions were spot-on by the way. I've now done this 4 or 5 times and, with thanks to you, can swap the mount out in less than an hour...

Max Energy

Tom,
I would be interested in your Semi Solid mount
225 573-0664
maxenergy@***.net

Jay Wellwood

Thanks for sharing your test results Tom.

Tom M'Guinn

I'd want to sell the cross member with it if I do, as I drilled open the holes for the bigger bolts, so it's really best used with this mount... It sure looks good sitting in the garage, but kind of a waste I guess... Let me think about that. Are you in immediate need for a mount?

fejjj

Older thread revival. I installed the xschop semi-solid mount and I have a ton a driveline noise.

URG8RB8

This is Not good news for me, I guess I will have to pull out my beautiful mirror polished mount. I thought with the urethane bushings it would not be that noisy. Never assume! At least Tom has provided a nice solution.

Tom M'Guinn

Everyone has a different tolerance level, but I have to say for me --on a street car-- it was WAY too much, even after adding sound insulation. The 60A filler with boxed-in brackets as been working great (knock on wood) and is pretty close to stock in terms of noise, with a tad more vibration at idle, but pretty civil street manners overall. Definitely recommend it...

fejjj

Tom,

Thank you for the follow up.

I was thinking I had something wrong in my driveline that was going to cost me another leg.

Auto_Werks 3.6

I have a urethane filled stock mount in my track car with no interior. When I first installed it, the noise level increase was holy $*&# loud. lots of gear noises etc. I ended up swapping that trans out for a lower mile AOR gearbox and the noise level went waaaay down. I have no reason to believe the first gearbox is "bad", just probably some more age. I guess what I'm saying is; the urethane mount doesn't have to be obnoxious on it's own, but it will still magnify other sounds if everything isn't 100%