"Upgraded" Motor & Trans Mounts - Worth it?

[FigureItOut]

I'm once again crawling under the Z to swap out some bits and make some changes. While I've got it all apart I'm debating replacing the motor and trans mounts which I'm sure have been there for all 100k miles on the clock. I'm inclined to "upgrade" from the OEM offering to a modest poly option (not solid or super hard, but still stiffer then the OEM rubber).

Other users who have swapped in poly bushings, what was your experience? Considerable increase in NVH? Did the car feel noticeably "stiffer" or more "solid"? Was it largely a waste of time?

Do you have any recommended products? Is this a complex part where I should invest or will more or less any poly bushing offering suffice?

[bwright657]

I can't speak for the 3.0i, but upgraded motor and transmission mounts make a big difference with the shift feel on M cars. And at 100k miles, the original parts are definitely worn out. A stiffer durometer rubber bushing will tighten things up without increasing NVH. I would stick with rubber for a car that is street driven.

Good brands to look for would be Vibra-Technics, Rogue Engineering and 034 Motorsport.

[GuidoK]

Originally Posted by FigureItOut

I'm inclined to "upgrade" from the OEM offering to a modest poly option (not solid or super hard, but still stiffer then the OEM rubber).

What do you consider a 'modest' poly option?
What stiffness?

I have both upgraded engine and transmission mounts. I think it's worth it.
I don't know if you'll be measurably faster on a track, but the car feels more like one.
With the stock mounts you feel the engine/transmission act like a pendulum, when coming out of say a roundabout where you have that quick balanceshift from left to right.
That feel is completely gone.

But if you go above ~shore 60A, that's considered pretty hard for engine mounts.

I have the vibra technics engine mounts, but if I had to buy enginen mounts now, it would definately be the ones from Powerflex.

As transmission mounts I have generic type A vibration dampners. Cost about $3/piece

[FigureItOut]

Originally Posted by GuidoK

What do you consider a 'modest' poly option?
What stiffness?

As transmission mounts I have generic type A vibration dampners. Cost about $3/piece

The options I've been looking at are 75A durometer. It sounds like these might be a bit too stiff for a "weekend fun" car.

$3 a piece is a steal compared to what I've been looking at. I gotta track those down.

[GuidoK]

75A is indeed stiff for motormount rubber. (for suspension rubber like bushings its normal, but the motormounts of course have a very diffenent type of load).

The transmission mounts are generic 'type A' (threads at both ends) vibration dampers.
I don't know the exact size anymore, maybe 30x30mm M8? I think they were shore55A or so. And that's already noticeable stiffer than the stock ones.
It's been a very long time since I did this mod, over 8 years ago I think.
I used 1 or 2 rings to match the exact height to the stock mounts:
(they are a little bit more narrow than the stock mounts but already way stiffer)

[wdb]

I have Vibra Technics motor mounts and stock but new trans mounts. Noticeable increase in interior noise from the motor mounts, but I would not go so far as to say there is more harshness and there is only a bit more vibration. M car, did it when I was doing the shifter because I was tired of missing second gear on downshifts. My 3.0si had no such problem and I would not have been inclined to try and improve shifting in the same way.

[Coi]

I did a lot of research on this but haven't changed mine from stock yet. I think that an upgraded solid rubber mount, rather than poly, is the best choice for anything but a dedicated track car. Gets you most of the way there in terms of stiffness without the excessive noise and vibration that polyurethane mounts transmit. Rubber also handles heat better and won't ever make noise.

The Bimmerworld performance engine mounts seem like a popular choice and cost about the same as new stock mounts. They're modeled off the 'Group N' mounts BMW used to sell (for a ridiculous $800).

ECS tuning just came out with a similar product with their 75A solid rubber engine mounts. These are cheaper than the bimmerworld ones but there are no reviews of them so I don't know of the quality or how they compare in stiffness.

I'm going to get one of these soon for my car.

[GuidoK]

Originally Posted by Coi

Gets you most of the way there in terms of stiffness without the excessive noise and vibration that polyurethane mounts transmit. Rubber also handles heat better and won't ever make noise.

In this case it's not the type of rubber that makes the noise or gives the vibration.
It's purely the stiffness.
I also wonder if normal rubber handles heat better than PU. Both materials don't react too good to heat. Also not all rubber is made equal.
There has been a case of VT mounts here probably fail due to heat. And those arent PU.

That person later switched to bimmerworld mounts, but reportedly those are considerably stiffer than VT ones and give more NVH feedback.

Nice thing about those powerflex ones is that you can regulate the stiffness. So I think they have the highest level of engineering.
No hands on experience though.
That'll problably come when my VT ones need replacing. But so far they still hold without a problem.
Too bad those powerflex ones are so expensive.

[kaybat]

I have the BimmerWorld mounts and like them, a little noisy when releasing the clutch, otherwise, they're fine.

[Coi]

Originally Posted by GuidoK

In this case it's not the type of rubber that makes the noise or gives the vibration.
It's purely the stiffness.
I also wonder if normal rubber handles heat better than PU. Both materials don't react too good to heat. Also not all rubber is made equal.
There has been a case of VT mounts here probably fail due to heat. And those arent PU.

That person later switched to bimmerworld mounts, but reportedly those are considerably stiffer than VT ones and give more NVH feedback.

Nice thing about those powerflex ones is that you can regulate the stiffness. So I think they have the highest level of engineering.
No hands on experience though.
That'll problably come when my VT ones need replacing. But so far they still hold without a problem.
Too bad those powerflex ones are so expensive.

Yeah, durometer matters more than material but I think generally rubber is softer than polyurethane and will absorb more vibration. Not always but usually. Another factor that confuses things is some being rated by shore durometer "A" and some by "D" when these are actually different tests and not really comparable. Durometer is more of a test of compression, flexibility, and deflection rather than vibration absorption but they are all obviously related.

In terms of handling heat, I always heard from people that track their cars that rubber FCABs and engine mounts hold up better than PU. I don't actually know if this is true; may just be pure speculation or based on anecdotal evidence. In terms of those VT ones that failed, I wonder if it was that the outer metal body close to the exhaust conducts heat much more than rubber would in that location. If the outer metal got hot enough and retained that heat it could damage the rubber inside while a pure rubber mount would've never conducted enough heat to get that hot.

I've heard the bimmerworld ones soften up quite a bit after the first 1000 miles, so the initial impression may not be indicative of their long-term nvh characteristics. Also in terms of engineering the BW ones copy a design feature from the OEM mounts that keeps the mounts from completely shearing in an accident.

While the power flex ones are expensive, they're not that much more than the VT. VT are $325-$350 and power flex are $400. Both are a far cry from the BW at $200 or the ECS 75A duro at $140.

[FigureItOut]

It sounds like I should be shooting for an OEM+ option rather than a poly solution. The BimmerWorld offering seems like a good candidate and come well recommended. Any thoughts on these as competitive offering?

And should I go ahead and swap in these while I'm at it?

[bwright657]

Originally Posted by FigureItOut

It sounds like I should be shooting for an OEM+ option rather than a poly solution. The BimmerWorld offering seems like a good candidate and come well recommended. Any thoughts on these as competitive offering?

And should I go ahead and swap in these while I'm at it?

The engine mounts look like a good option for a regular 3.0. But I would just go ahead and spend the extra $10 for the Rogue Engineering transmission mounts.

[filtercoffee]

I'm pretty happy with the stock mounts

[GuidoK]

Originally Posted by Coi

Yeah, durometer matters more than material but I think generally rubber is softer than polyurethane and will absorb more vibration.

that (natural) rubber is generally softer than PU is not a result of the type of rubber. You can make both natural rubber and PU rubber in fairly soft and fairly stiff compounds.
That PU rubbers are generally stiffer, is because they are used as uprated suspension parts. And that usually means better performance in terms of better roadholding/cornering/etc.
Uprated parts are rarely uprated because they are softer and the person that buys the parts wants a more vague and cushioning ride.
But natural rubber can be made very very hard just as well (for instance ebonite)

Not always but usually. Another factor that confuses things is some being rated by shore durometer "A" and some by "D" when these are actually different tests and not really comparable.

Someone that mixes up the Shore A scale and the Shore D scale is just an idiot. They are comparable in the sort of test (compression of material) but in a totally different stiffness range.
That difference in stiffness indeed requires an adapted way of testing, where the part that is pressed into the rubber has a different shape and is done with a different force.
But indeed, any rubber that is specced in the shore A range is way way softer than a rubber specced in the shore D range.
Shore A feels from very soft (low in the range) to very hard rubber high in the range, but in the shore D range everything feels hard as nails, and there is no real dampening anymore. I don't think a difference between shore75D and solid metal can be felt for example.

rather than vibration absorption but they are all obviously related.

Indeed, vibration absorption is also very much related to the design of the part (shape, holes etc), but that goes for both natural rubber mounts as PU mounts.

I've heard the bimmerworld ones soften up quite a bit after the first 1000 miles, so the initial impression may not be indicative of their long-term nvh characteristics.

I can't really comment on the heat part (haven't had a single PU suspension part fail), but what you write here is very much a downside of natural rubber, and it doesn't stop at 1000 miles.
The stiffness of natural rubber changes continuously and to a big extent over their lifecycle. This goes gradually so you don't really notice this but there always is this saying about a 'new car feel'. At the end of their lifetime, natural rubber is way softer than when it was new.
And that is I think the main big advantage of PU. PU always keeps it's factory stiffness, so a new PU rubber performs exactly the same as an older one.
The feel of your car doesn't change over time with PU (rubberwise)
And what I can say, is that some of my powerflex suspension rubbers have been holding up for a longer time than the original BMW rubbers did. And that without changing its characteristics. So I can't speak for all the rubbers in the suspension, but at certain points PU is measurably better in both lifespan and lack of quality degrading.

Also in terms of engineering the BW ones copy a design feature from the OEM mounts that keeps the mounts from completely shearing in an accident.

I can't speak for the powerflex ones (havent taken one apart), but the Vibra Technics ones are also designed in this way.
The powerflex ones do have an internal metal part constructed to the bolt that holds the motor support, but if it's larger than the hole in the outer casing, I don't know (if it is, then that also doesn't come apart when shearing)
My guess is that the powerfles ones are also designed this way but I don't know for sure.
But the powerflex ones look like the most advanced engineered ones to me. They use different parts with different stiffnesses in there (maybe to dampen different frequencies) and with the capability to change stiffness. (but I don't know in what range that works). They are certainly unique in that way.
Of course the OEM ones are fluid filled so that also is quite a complex design. But soft and prone to age.

[FigureItOut]

This may be a whole new can of worms, but I'm considering replacing the Guibo while I'm in there swapping bits. I'm sure the factory one is well worn by now and mostly useless.

Any thoughts on the "aftermarket" options that use an aluminum carrier and poly bushings instead of rubber? One listing warned that if your driveline isn't perfectly centered and balanced it could be ruinous. Thoughts?

[GuidoK]

Originally Posted by FigureItOut

Any thoughts on the "aftermarket" options that use an aluminum carrier and poly bushings instead of rubber? One listing warned that if your driveline isn't perfectly centered and balanced it could be ruinous. Thoughts?

My first thought is: why?
What performance benefit is to be expected from an aluminium/poly giubo?
The original rubber one isn't exactly rubber; it contains high strength kevlar? fibers that are wrapped around the internal metal bolt bushings.
So for directness of power transition, I don't think anything real can be gained. (and with having a dmf, that is also really not an issue)
Tbh I think the kevlar strands might even be stronger than the PU rubber.
The original giubo isn't a part with a known short lifespan.

And as for strenght: I run a twinscrew supercharger with cams&headers, putting out roughly 465Nm, and the stock one has no issues, so the original 310Nm of the 3.0i is no problem at all.

Maybe a z4m giubo conversion is slightly stronger. I think that one might fit with the z4m bolts. The bolts are 3mm longer so I think the z4m giubo might be 3mm thicker so maybe a little bit stronger.

If you have a high mileage car (100k miles+) preventative replacement of the giubo is always good.
But that job is a completely different job than swapping out motor mounts.
Swapping out motormounts is a 15min job, one of the easiest jobs on the car....
Swapping out the giubo..... not so much. The exhaust system has to come off and if that hasn't happened regularly, that means the cutting tourch....

[FigureItOut]

Originally Posted by GuidoK

My first thought is: why?
What performance benefit is to be expected from an aluminium/poly giubo?
The original rubber one isn't exactly rubber; it contains high strength kevlar? fibers that are wrapped around the internal metal bolt bushings.
So for directness of power transition, I don't think anything real can be gained. (and with having a dmf, that is also really not an issue)
Tbh I think the kevlar strands might even be stronger than the PU rubber.
The original giubo isn't a part with a known short lifespan.

And as for strenght: I run a twinscrew supercharger with cams&headers, putting out roughly 465Nm, and the stock one has no issues, so the original 310Nm of the 3.0i is no problem at all.

Maybe a z4m giubo conversion is slightly stronger. I think that one might fit with the z4m bolts. The bolts are 3mm longer so I think the z4m giubo might be 3mm thicker so maybe a little bit stronger.

If you have a high mileage car (100k miles+) preventative replacement of the giubo is always good.
But that job is a completely different job than swapping out motor mounts.
Swapping out motormounts is a 15min job, one of the easiest jobs on the car....
Swapping out the giubo..... not so much. The exhaust system has to come off and if that hasn't happened regularly, that means the cutting tourch....

I've had almost the whole underside off in the last year or two, including a completely new exhaust system. I'm swapping the differential out for a different final drive and LSD conversion. The engine & trans mounts are an add-on task while I'm down there. My thought was if I'm already messing with the driveshaft I might as well refresh some of the wear items associated.

I agree the "solid" guibo seemed unnecessary and I'm glad to hear the factory one isn't just mushy rubber. It sounds like simply refreshing that should see me through for the life of the car.

[lelandr]

I haven't installed them yet, but I have purchased the BW Group-N copies and the Rouge gearbox mounts for my Z4MC track project. I'm looking forward to this, but I had to go with the AKG stuff at the back as there isn't another supplier.

I normally don't like the urethane stuff. I broke so much of that on my E30 M3 track rat that I ended us using upgraded parts from the BMW catalog, which worked great.

That being said, the poly stuff seems as if's improved over the last 10-15 years, so maybe, but it's still a compromise.

I'd be able to let you guys know how the mounts are going, but I messed up one of the rear inner brake lines and am still waiting (since early July) for replacements, so this car has been on jackstands for months.

[GuidoK]

Originally Posted by lelandr

for my Z4MC track project.

If you're making a 100% track car you can go with virtually all solid connections.
So if you want polyurethane in that, search for the hardest compound you can find (maybe that was the problem with your specific PU applications; too soft). That will also be the strongest bushing, as the hardest is usually most resistant to tearing.
But something like polyoxymethylene or solid metal will be stronger.
Of course you need something more flexible for joints that move in more than 1 direction, or a pillowball.

[Michael9218]

All my mounts are aluminum or spherical bearings...I wear ear plugs...