Ok, I need help. Really terrible engine vibration on M50 swap.

[static]

i bit the $1000 bullet and just did all SS custom, with artlike craftsmanship. 2.5 single mandrel here.

[triggrhaapi]

i run IX, fins are shaved, 6-7mm spacer is on driver side, and the clearance is only 2-3mm

Which engine mounts?

[1990m3]

i bit the $1000 bullet and just did all SS custom, with artlike craftsmanship. 2.5 single mandrel here.

what motor are you running? which headers do you have? I'm thinking of 3" single mandrel for my system, looking for ideas.

[static]

triggrhapi: e28m5 both pass side i believe (might be e34m5 i don't remember now)

1990m3: us s50, stock cast mani, plan to change for s52 ss mani since no modification to downpipes is necessary.
I though of going 3" but figured 2.5" mandrel straight through is enough for S50

[dougsic]

The reason why spacers might be needed on the passenger side is to clear the stock exhaust manifolds. Otherwise it will interfere with the swaybar. I guess you can always bang an indentation into them in order to clear the sway, but I figured I'd leave well enough alone.

I didn't have to shave any fins. I'm using a 320i booster though.

I tried using aftermarket E36 headers and though they cleared the swaybar fine, they interfered with the passenger side floor. I think if I put a few spacers on the driver's side I could have run them. I might just do that. :)

I have e28 M5 green engine mounts, e21 320i booster and ebay e36 headers.

I had to shave the manifold even before installing the headers. With stock e36 exhaust manifolds no engine mount spacers were used but the stock e36 downpipe was bashed in to clear the swaybar.

The e36 headers came with two spacers, each pretty thick at .397". I first installed them but proved to be thicker than I needed.

The e36 headers didn't come close to the sway bar but they do come close to the engine crossmember.

With the washer pictured below installed only on the passenger side, I still have enough clearence between the headers and the crossmember to fit a US quarter between the two.

The headers have no fitment problems with that one washer installed.

Connecting them to the stock e36 exhaust only required I cut the stock downpipes about 18" back. The headers came with slip clamps to mate up to the e36 exhaust and they worked pretty well.

[ArtClassShank]

Anyone know if I can switch from E21 mounts back to E36 mounts if Im using a ZF.

I have E21 mounts and cups right, but Id like to switch to something softer. Does the fabricating you have to do for E21 mounts ruin any chance of using E36 stock mounts?

Thanks

[FredK]

The only issue with running the E21 mounts is that the crossmember is now drilled for 10mm studs, rather than the 8mm studs of the stock e36 mounts. The drivetrain alignment can easily be off. You might be OK, though.

In my opinion, the E36 transmission mounts are a liability during hard driving, as the mounts are really soft and allow the engine and transmission to move around, which can cause you to misshift.

Are you having noise/vibration issues?

[ArtClassShank]

The only issue with running the E21 mounts is that the crossmember is now drilled for 10mm studs, rather than the 8mm studs of the stock e36 mounts. The drivetrain alignment can easily be off. You might be OK, though.

In my opinion, the E36 transmission mounts are a liability during hard driving, as the mounts are really soft and allow the engine and transmission to move around, which can cause you to misshift.

Are you having noise/vibration issues?

Right now I have a very large vibration coming from the transmission tunnel area. Right around 1800-2200 RPM. Its present at idle revving and while under load. Turns the seats into a low massage setting type deal.

Right now I have cups and e21 mounts, wondering if the cups are causing it.

[FredK]

Yeah, E21 mounts with cups don't transfer THAT much vibration to the cabin.

I've run E21 mounts with no cups and the car had no vibrations. If it helps, you can remove the cups and see if that removes the vibration. My bet, however, is that something more major is touching the frame of the car somewhere--headers on the front subframe or intake manifold on the brake booster.

[ArtClassShank]

Yeah, E21 mounts with cups don't transfer THAT much vibration to the cabin.

I've run E21 mounts with no cups and the car had no vibrations. If it helps, you can remove the cups and see if that removes the vibration. My bet, however, is that something more major is touching the frame of the car somewhere--headers on the front subframe or intake manifold on the brake booster.

My headers are extremely close to the front frame, do they expand a bit when hot?

I'll get some pictures.

[FredK]

I've had them pretty close before, maybe a few sheets of paper's worth of clearance between the pipe and the subframe, and suffered no noise or vibration issues.

The only time I've had a persistent vibration was when I had a bad driveshaft. I really didn't want it to be a bad driveshaft as they aren't the cheapest fix. However, since you have a vibration with the car in neutral and while revving the engine, it seems it is an interference issue.

[butters]

Fred, can you describe the vibration you had that was cured with the driveshaft?

I have been searching for some time now chasing roughness & drivetrain vibration I get while accelerating/decelerating around 3k rpm, and really just while driving at above 3k rpm (highway). Re-balancing the wheels helped, I corrected my giubo installation, and the giubo & CSB show zero signs of wear. I didn't drop the CSB at the time, so I suppose the u-joints could be bad, but virtually no rotational play in the u-joints is detectable.

When I put the clutch in the feeling goes away as revs drop, but if I free rev I think it's still noticeable. I'm starting to contemplate the flywheel (OE dual-mass) as having gone. But I also will be inspecting my (e28 green) motor mounts.

[FredK]

My vibration was a harsh buzzing that would easily last tens of seconds, and could be felt in the car while in gear and rolling. It was not present in idle, or while revving the car while stationary.

The vibration was a lot more common on the highway, but it was hard to replicate. I'd get it probably more often on deceleration than on acceleration. I could sometimes get the vibration to go away while coasting by goosing the throttle.

I figured it might have had to do with a rebuilt diff, but the vibration persisted after I swapped it out for one in known good condition. I had a new CSB and flex disc, and a low mileage 328i driveshaft. I checked the center joint for notchiness prior to installation, and it was only lightly notchy. Still though, if all those were good, but the vibration persisted, then my diagnosis was not correct.

It sounded like my car was shaking itself apart, so I decided to install a known-good driveshaft. The vibration went away. The known-good driveshaft still has some vibration to it, but it also has around 200K miles on it now. I'll probably get a rebuilt unit over the winter.

The driveshaft I pulled had some play in the joints which I hadn't previously inspected for. It is extremely slight, but, it was enough to cause quite a ruckus while driving.

[ArtClassShank]

http://imgur.com/3uSK3JT

http://imgur.com/TvFbBZY

Heres pictures of my header clearence and my green engine mount.

Is this acceptable?

[FredK]

It looks like the header collector is rubbing directly on the subframe. It looks like there's some rust there from the paint being rubbed off.

If I were you, I'd put a 1/4" spacer (like some fender washers) underneath the passenger side engine mount arm. It's worth a shot, anyway.