Solid vs Poly vs OEM Motor Mounts, what do you run?

[pMak26]

I need new motor mounts on my track car, e46 m3. Looking for some opinions to definitively decide on which motor and transmission bushings to install. Are solid mounts good to use or do they cause issues elsewhere? Poly, OEM? What do you run?

TIA

[bluptgm3]

If you are going to run solid (aluminum) bushings, I would recommend reinforcing the subframe at all the attach locations and reinforce all the same attach locations in the unibody. ....and pay forward your dental plan (filling replacement)


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[aeronaut]

I use bowling ball hard poly.
You "must" run solid or hard poly if you have a CAE type shifter (the type that hard mounts to the chassis).
But yea, it is kinda an all or nothing thing. Hard poly/metal for engine, trans, diff, plus all the reinforcements.
If it's DD and you still have carpet, OEM is the way to go IMO.

[pMak26]

It's a caged race car. Solid just seems like asking for trouble in sending 100% of the vibration through the chassis and mounting points. Basically asking cracks to form. But if others are running solid, I'd do it.

[pMak26]

It's for this car:

[cohny]

I asked the same question in the E36 track group in FB and it seemed like the vast majority of responses, espescially from those with shops, were that solid is a bad idea and not worth it over a 75D poly bushing (bowling ball).

Cracked transmission housings, cracked subframes, engine issues etc. were all mentioned. Maybe for pro race teams that are rebuilding their cars every weekend the tiny performance gain is worth it, but for a home-privateer I'd skip it.

[pMak26]

I asked the same question in the E36 track group in FB and it seemed like the vast majority of responses, espescially from those with shops, were that solid is a bad idea and not worth it over a 75D poly bushing (bowling ball).

Cracked transmission housings, cracked subframes, engine issues etc. were all mentioned. Maybe for pro race teams that are rebuilding their cars every weekend the tiny performance gain is worth it, but for a home-privateer I'd skip it.

This is the kind of feedback I was looking for! Thank you, 75D it is.

[ScotcH]

I asked the same question in the E36 track group in FB and it seemed like the vast majority of responses, espescially from those with shops, were that solid is a bad idea and not worth it over a 75D poly bushing (bowling ball).

Cracked transmission housings, cracked subframes, engine issues etc. were all mentioned. Maybe for pro race teams that are rebuilding their cars every weekend the tiny performance gain is worth it, but for a home-privateer I'd skip it.

Total bullshit ... we've run solid aluminum in every race car for years now (like 10 years+) and the only time anything breaks is in a crash. Just weld in a small plate on the subframe, and you're done.

I'd say stick with the BimmerWorld motorsport copy engine mounts, or on a caged car, go solid. But that's just my opinion (based on 5 race cars built and campaigned).

[S14]

It's for this car:

Bring your camera down and forward. You can't really tell what is going on in relation to you, the car and the track.

[jimmypet]

Total bullshit ... we've run solid aluminum in every race car for years now (like 10 years+) and the only time anything breaks is in a crash. Just weld in a small plate on the subframe, and you're done.

I'd say stick with the BimmerWorld motorsport copy engine mounts, or on a caged car, go solid. But that's just my opinion (based on 5 race cars built and campaigned).

^^^^^ This ^^^^^^
Look at what the factory uses in the factory race cars.
I cant say I have ever done it on a later 6 cyl, but I tried every motor mount known to man (and even some that I built myself) in my E30M3 race car and the hands down, home run, winner, best motor mount ever was a direct copy of the factor BMW Motorsport Gruppe A mount.
Look at what BMW Motorsport used when they campaigned your chassis, use that.
If Bimmerworld makes a copy, buy them.

[jakermac]

I slowly over time changed everything from OEM like bushings to sphericals and 75D. The only change I regret is changing from Powerflex purple to solid aluminum on the rear subframe to chassis. The car was somewhat pleasant to daily drive until I did that. Then the diff whine got louder than I cared for. I’m 99% positive that it had nothing to do with the diff “going south” as it was set up by one of the most trusted shops in the Pacific Northwest.

The engine/trans were on Vorshlag 95A and 80A (Red on motor, orange on trans). The key for me was making sure that I got the torque on the mounting studs “just right”. A little too tight and I got lots of vibration. And obviously you don’t want them too loose.

[propcar]

I had read good things about these as well.

https://www.moreheadspeedworks.com/p...engine-mounts/

[golgo13]

Just another data point for those interested.

I've been on 75D (Orange) Rev Shift motor, trans, rear subframe and diff mounts for about four years and 32 events now without issue.

[Feffman]

I found a happy medium with Vorshlag's poly/aluminum hybrid mounts. You get the benefit of solid and poly mounts in a single application. One note, whatever mounts you use, make sure you secure the nuts, even if they are nyloc, with blue Loctite and paint mark them to make sure they stay in place.

Transmission: https://vorshlag-store.com/collectio...-durometer-set

Engine: https://vorshlag-store.com/collectio...13-upgrade-kit

Only issue is you MUST loosen the Vorshlag motor mounts if you pull the tranny or they will break.

Feff

[BlackHawkRacing]

I went with poly (Vorshlag specifically) over aluminum on the advice of a friend who's family has been racing sports cars for 20+ years. The concern my friend pointed out was that in the event of an accident, the solids transfer more energy and break other components. He's seen more than few engine blocks be the item that failed. With poly, the mounts are more likely to be the fail point. Regardless of how slight the risk may be, to me, going with poly was a good way to reduce this risk for someone who is just club racing.

Terry Fair has a good post somewhere on why Vorshlag chose poly over metal; I keep trying to find it but have not been able to; if anyone does, please post it.

I also hate the logic that "it's what motorsports professionals do, so we must follow them." Factory race teams also have multi-comma budgets, professional everything and engineers with intelligence levels I can't fathom, so the idea we should always copy them is illogical. 99.9% of people on this board will not be able to discern the difference in car performance between the poly and the metal variant.

If you are worried about the poly failing overtime or from heat exposure, turn it into a wear item by buying the Revshifts ones from FCP and taking advantage of the warrantee. Here is a link to the 75D motor mounts for an E36 (they also sell 95 and 80a variants)

https://www.fcpeuro.com/products/bmw...hift-pmmr3675d