Solid/Poly/UHMW Motor Mounts

[Vivek]

Who runs them? My m42 tends to vibrate a lot sometimes at idle, and I've heard that the m42's vibration can crack the subframe on solid mounts. Any more info on this? I'll eventually be doing all my suspension bushings, hopefully with ones from Silence, and I'd like to do the motor and tranny mounts in UHMW too. All I'm worried (at this time, just curious) about is if the m42 can actually damage something if it's sitting on solid mounts.

[Massimo]

I don't know if it is just the M42, but I would think so. Mine with a chip has a idle like a wild cam and shakes alot. If I was doing it I would remove the subframe and have it strengthened. 4 bangers and v8 are not very smooth due to the 90 degrees in timing unlike a 6 or a 12 with 60 degree timing.

[Vivek]

What would you do to strengthen it?

[iwantspeed]

To order:

Front Subframe Engine Mount Reinforcement Plates
For BMW e30
4-piece set
#RFSP30
$30.00

http://www.akgmotorsport.com/catalog/catalog.php?category=e30%20Chassis%20Reinforcement

[bmwman91]

Well, looks like I know what I am ordering for my motor swap this coming weekend...!

Vivek,
Is your car a track car or a daily driver? If a DD, don't get solid mounts. I ran E28 535i mounts for years (solid rubber) which were significantly stiffer than the stock hydraulic ones, but the vibration and noise were really bad. New stock ones are plenty stiff, although a little pricey. There is a reason that they put soft ones under the M42.

[Vivek]

It's a DD, but I honestly don't care about comfort over performance (I ran with <1" travel in the rear for like a month, only raised it to fit spacers). If the e28 mounts are stiff enough and won't damage anything, I may just get those and solid tranny mounts...but I've also heard that the tranny mounts are more the cause of increased NVH than motor mounts. Which tranny mounts did you have?

[bmwman91]

I have always used stock tranny mounts. The 318iS just doesn't make enough torque to necessitate beefier mounts there.

I think that E28 535i motor mounts are a good way to go. They are stiffer, cheap as fuck, and probably aren't as bad as solid ones. Trust me, if you put in E28 ones, the first time you start your car you will think, "wow, I am glad I didn't put solid ones in." And then you will spend the next week discovering 37 new buzzes and rattles at idle lol.

Maybe I am just getting old lol...12 years of DDing an E30 can do that. I ran a full poly suspension & diff mount for about 5 years. At the time, I thought that it all made a huge improvement over the stock rubber. Well, of course it did; the stock rubber that it replaced was 15+ years old and shot to hell. Once I finished school & had money, getting stock bushings pressed in became affordable (the real reason I went poly was that I was too cheap to pay a shop to press stock ones in lol) and I put all new stock rubber in everywhere. The car handled at least as well, while being far smoother and quieter at the same time. My theory is that stock rubber is best on the street where road quality varies widely since the rubber is compliant and allows the suspension to comply with road irregularities when cornering. Poly is better if you are on a track with perfect asphalt, but actually hurts performance on uneven road surfaces.

Anyway, try out the E28 motor mounts. I would hate to drive a car that noisy on the highway for more than an hour now, but 10 yeas ago it seemed fun to have the "racecar" experience.

Oh, look into getting a front toe alignment too. That's the only thing that can be aligned on an E30 (unless you have aftermarket camber plates or something) and I can usually talk shops into a lower price because of it. That always made a big difference in handling performance if it hadn't been done in a while or I had the struts off.

[Vivek]

Thanks, I'll go with the e28 mounts. When I replaced my tranny mounts with new(ish) rubber ones, the shifter feel was 10x better, so I was wondering if maybe it'll be even better with stiffer mounts. I'm gonna do offset cabs, and I'll get the toe aligned after that.

[bmwman91]

Good call. An alignment makes ALL the difference!

I don't think that beefed up tranny mounts will help you too much on an M42, unless it is turbo'ed or something.

[Balleristic31]

I had silences mounts on my trans and it was so loud you had to yell at the person next to you as you drove.

Not for a street car lbv. No one will like you, including yourself.

[Massimo]

It's a DD, but I honestly don't care about comfort over performance

Yet you drive a vert lol.

[Threehz]

^^ what he said for one.

I bought my car with poly mounts, and for the first hour I was like cool, these aren't all that bad. You don't want poly mounts, or any mounts close to that stiff with an M42 unless you are tracking the car.

I wouldn't say that it was horribly annoying, but when people are in your car it's embarrassing, and personally I felt as if the vibration had to be causing problems, shaking shit loose, and was no good for the vehicle.

When I switched to stock mounts it was like night and day better. My idle smoothed out and dropped from 1100 down to around 800, no more annoying rattles at idle (and every other RPM), the car literally felt like it performed better in every way.

That's just me, do what you like, E28 mounts are cheap as hell and you can always go back to stock.

[Vivek]

Yet you drive a vert lol.

It's fun but not comfortable. I should have worded that as "Comfort over fun". Because verts are crazy fun but you have to put on tons of sun screen just to drive somewhere and you can barely talk on the highway. You can bounce off the seat over big bumps and it can be annoying to drive really slow because of no PS, but I wouldn't have it any other way. I know a guy around here with all silence bushings and I'll try to take a ride in his car one time and see how it is. I'll probably go with e38 mounts and keep my rubber trans mounts, but eventually i'll get a x-brace from ejnight and all UHMW bushings.

[bmwman91]

Just out of curiosity, are you 18-19 years old? This isn't intended as an insult or anything, just a guess based on the profile pic. I was EXACTLY the same way at that age, and by 24 had ridded myself of almost all of the "performance" suspension stuff. Older guys told me the exact same stuff lol, but the only way to actually learn is to go through it. How else WOULD the older guys know?!

[Threehz]

I can see the appeal, but for a DD I don't think it's a decision that anyone will end up enjoying after a certain amount of time. If I had a second E30 to mess around with then that would be a different story.