e30 m42 with e36 m3 mounts & idle vibration

[dullrot]

I'd read that e36 m3 mounts could be used to replace the stock e30 m42 mounts, provided the locating tabs on the motor mounts were shaved off.

I did this, along with e21 transmission mounts, and while many things are worlds better than they were with 200k mile torn oem trans mounts and one leaking pass side engine mount, I'm noticing vibration in the cabin when stopped.

Since the new mounts definitely have the motor sitting higher than it was before, I'd be suspecting driveshaft alignment, but this happens at idle (a steady 5-600rpm in neutral), so the driveshaft would not be spinning.

Was the e36 m3 motor mount idea bunk info? If I should ditch them I'd likely look at the e28 535i mounts, the oem m42's are too damn expensive.

[Dj Buttchug]

theres a reason m42 mounts are expensive. this is that reason.

[dullrot]

because they are fluid filled? The e36 m3 ones are fluid filled as well. Same style mount, just slightly less space between the locating tab and the stud. Seem a little taller, but that may be due to 23 years and 200k.

[dullrot]

for whatever reason, the vibration was gone today. Completely gone. I'd recently gotten gas, and also tightened up the banjo bolts on the PS pump. Did rack swap at the same time as the motor mounts.

I suppose the pump could have been vibrating due to air being drawn in through the pump? I'd been having loud whine with steering at full lock, despite several bleeding sessions and a few dozen miles driving. That's gone now as well. Whatever it was, yay.

[AustinK425]

Get m42 mounts.

[roguetoaster]

I doubt the mounts contributed to that occurence of poor idle. Also, 5-600RPM is a bit low. Maybe you should get it back up to spec?

The more I think about it the more I dislike the idea of putting in engine mounts with no locator tab. Somehow it seems like there could be issues with stressing the mount studs, although I have no evidence to back this up. Further, it would be a good idea to reinforce the subframe if you go to solid mounts.

I would strongly urge you to go back to stock mounts as they will last for 5+ years with no real issue (unless all you do is track it) and are by far the best mount for the M42.

[dullrot]

As I said, the NVH/vibrations are gone - I think they were more related to the PS swap. The e36 m3 mounts are not solid, they are the same style as the stock m42 mounts. Rubber and hydraulic.

I'll keep an eye on them, I put the car on the lift at least once a week.

[roguetoaster]

As I said, the NVH/vibrations are gone - I think they were more related to the PS swap. The e36 m3 mounts are not solid, they are the same style as the stock m42 mounts. Rubber and hydraulic.

I'll keep an eye on them, I put the car on the lift at least once a week.

I understood all of that to be true when I replied. If you can do update this thread if you see the engine mounts shifting from starting position or signs of metal fatigue.

[mrmckie]

How are these mounts holding up?

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[fresh_TD]

$150 worth of motor mounts is expensive? Lol

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[varg]

I have the green E28 motor mounts, they've held up to my abuse so far and I haven't noticed too much vibration. Another good cheap alternative to OE. Stiffer than old worn out stock mounts too, so good for turbo cars.

[ccsdo5]

I have some solid UHMW mounts I got off a member for like $70. You want to feel a rattle, my car seems like it is going to shake apart when idling. I've been thinking of getting better mounts since the ones I have sit my engine a little higher anyway.

[roguetoaster]

I have some solid UHMW mounts I got off a member for like $70. You want to feel a rattle, my car seems like it is going to shake apart when idling. I've been thinking of getting better mounts since the ones I have sit my engine a little higher anyway.

By better you of course mean stock M42. At last check they're available on rockauto for $17 each, and should still be in stock.

[fresh_TD]

OE M42 mounts are $75 a piece. Totally worth it.

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[DER E30]

Raise your idle