Engine & Trans. mounts: Hardened rubber or poly bushes?

[elky]

Hi all, I am planning a service for my engine and transmission mounts as I know they are 20 years old and there is quite some annoying movement when lifting off etc.

My question is if anybody has recommendations?

I was looking at the Garagistic 80a mounts but after seeing a storry on reddit with a guy that went back to OE mounts I am not quite sure.

And I've also found that there is company HardraceEurope that sells a kit of hardened rubber https://www.hardrace-europe.com/harden-engine-mount-transmission-mount-7364.html.

Does anyone have experience with either one or other choices?

 

[t-tony]

If you haven’t up graded the engine why would you want harder engine mounts? If the original ones have lasted 20 years from new, genuine ones from BMW will likely last just as long. Harder rubber mounts for motor and gearbox are likely to give you vibration through the car. Maybe that’s why that other man went back to OE mounts?

Tony.

 

[IainP]

Hi all, I am planning a service for my engine and transmission mounts as I know they are 20 years old and there is quite some annoying movement when lifting off etc.

My question is if anybody has recommendations?

I was looking at the Garagistic 80a mounts but after seeing a storry on reddit with a guy that went back to OE mounts I am not quite sure.

And I've also found that there is company HardraceEurope that sells a kit of hardened rubber https://www.hardrace-europe.com/harden-engine-mount-transmission-mount-7364.html.

Does anyone have experience with either one or other choices?

Yes, you’ll hate them.
Fitted a set of poly mounts to my sons e36 and he removed them fairly quickly, the vibration was horrible.
I’ve just fitted new mounts to mine, even though I’m going to do some competition in it I’ve fitted standard mounts.
The originals will be like this, squished.

 

[elky]

If you haven’t up graded the engine why would you want harder engine mounts? If the original ones have lasted 20 years from new, genuine ones from BMW will likely last just as long. Harder rubber mounts for motor and gearbox are likely to give you vibration through the car. Maybe that’s why that other man went back to OE mounts?

Tony.

I am curious about the "hardened rubber" as I see a few people fitting this instead of polyurethane bushes. Moreover, I thought that potentially it would be a good match since I've already fitted the Powerflex differential mount and I am very pleased with my diff. mount although I've read people complaining.

Anyway, that is why I wanted to discuss mounts and hear opinions

 

[IainP]

I’ve filled in the voids in the mounts of my front and 4wd cars to reduce engine movement, but those have been driven very hard indeed. It reduces engine movement for a faster launch without exhaust movement.
It does however increase vibration at idle, my engines were balanced to the n’th degree, so it wasn’t that much of a problem in my cars, I knew it would beforehand, and I was prepared to live with it.
I’m my sons case, his car was heavily lowered, the poly mounts were in conjunction with raising plates to ensure he didn’t hit the sump. He couldn’t put up with the extra vibration at all.
In a front wheel drive car it’s fore/aft, not so noticeable. Rwd it’s side to side, much more noticeable inside the car, often also feel the gearstick “buzz” in your hand is the only way to describe it.
As I say, I’ll be doing trackdays and Hillclimbs, the engine isn’t balanced (yet) and I’m sticking with standard mounts. Pure road car, I wouldn’t even consider it myself.
The poly diff mount is a different story, a single mount to restrict torque transfer is a silly idea.
My opinions anyway, they are from experience though I’m sure others will disagree strongly.

 

[Delk]

I have poly mounts in my car and stock in my missed. My car is not normal so I have no issues and don't think they are bad.
People also sell solid trans mounts and I have never heard anything good about these. Stick with stock in the back.

 

[elky]

I have poly mounts in my car and stock in my missed. My car is not normal so I have no issues and don't think they are bad.
People also sell solid trans mounts and I have never heard anything good about these. Stick with stock in the back.

Thanks for your input, but I am not sure I understood, what is not normal with your car and is the "missed"? Also if you want to share what type of hardness do you have for poly mounts? No definitely I am not thinking for solid ones!!!

 

[elky]

I’ve filled in the voids in the mounts of my front and 4wd cars to reduce engine movement, but those have been driven very hard indeed. It reduces engine movement for a faster launch without exhaust movement.
It does however increase vibration at idle, my engines were balanced to the n’th degree, so it wasn’t that much of a problem in my cars, I knew it would beforehand, and I was prepared to live with it.
I’m my sons case, his car was heavily lowered, the poly mounts were in conjunction with raising plates to ensure he didn’t hit the sump. He couldn’t put up with the extra vibration at all.
In a front wheel drive car it’s fore/aft, not so noticeable. Rwd it’s side to side, much more noticeable inside the car, often also feel the gearstick “buzz” in your hand is the only way to describe it.
As I say, I’ll be doing trackdays and Hillclimbs, the engine isn’t balanced (yet) and I’m sticking with standard mounts. Pure road car, I wouldn’t even consider it myself.
The poly diff mount is a different story, a single mount to restrict torque transfer is a silly idea.
My opinions anyway, they are from experience though I’m sure others will disagree strongly.

Ha! It sounds like you have quite some experience with all types of vehicles, thanks for the inputs, and I hear what you are saying for a pure road car. My use is mainly for spirited road use & very rarely (unfortunately) I might visit the track.
I've driven an MX5 which had poly mounts and although there was vibration in the gearstick and in idle it felt very well tight together.
But you haven't tried hardened rubber mounts like Rogue Engineering or Hardrace Europe? https://www.hardrace-europe.com/harden-engine-mount-transmission-mount-7361.html

 

[IainP]

No, never tried those. Back in the day we just filled the mounts with polyurethane adhesive, or bits of nylon held with poly adhesive. Cheap and dead easy to do. Nowadays there are pop in kits for most fwd cars.
I’ve never had a BMW engine apart to examine it.
Back in the day I used to play with Suzuki’s, SJ’s, Gti and the like, rebuilt more than a few engines. Because I had the stuff I’d balance rods and pistons for people, to a daft degree really 0.1g +\- 0.05g. I can even better that now, cos I’m stupid that way.
Japanese are very well balanced from the factory, usually under a gram disparity across the pistons or rods. Gm, not so much, the Redtop wasn’t bad, American stuff awful, K series is well known to need balancing. Honda are excellent.
People will tell you it doesn’t make a great deal of difference. It DOES.
My built Swift engine I could balance a 50p on the block, didn’t fall over until beyond >5000rpm, my wife’s Rover, that fell over before1500rpm. I should actually try that on my M44 some time, just out of interest.

Transverse engine, I would say stiffer mounts are a must for any sort of spirited use. I’ve torn standard ones pretty much out of the car.
Longitudinal engine, unless it’s high power, or it’s being sprinted/hillclimbed where you’re dumping the clutch a lot for tyre warming/launch, it wouldn’t be for me. I may change my mind when I eventually get round to balancing the motor and fitting a lightweight flywheel, but I’ll probably stick with the new mounts I’ve just fitted initially and see how it goes.
One thing poly, or harder, mounts are good for is if you have a custom exhaust. Minimising engine movement means you can package the exhaust tighter/higher without knocking on anything under hard acceleration/braking.

 

[Delk]

Thanks for your input, but I am not sure I understood, what is not normal with your car and is the "missed"? Also if you want to share what type of hardness do you have for poly mounts? No definitely I am not thinking for solid ones!!!

Sorry I misspelled misses. Both of us have Z3s. Mine is more of a play toy and hers is more normal.
I dont remember exactly what mounts I have but they are the softer of the two available. I dont mind vibration in mine but its not harsh as far as I am concerned. My car is lowered on stiff suspension, big brakes and turbo charged. Between the noise and ride the engine vibration isnt noticeable. But for long drives her car is much more comfortable.