Motor Mount Options?

[Z3_GoCar]

I've started purchasing parts to put the race car back togeather. One thing I've though alot about but haven't pulled the trigger on are the motor and trans mounts. I'll just go with stock trans mounts, but what about the group-N or equvalant motor mounts? I'd rather have a mount that hold up a little better and doesn't allow the motor to come loose and start banging around like it did. I've got to replace the trans-cross member and shift linkage, and maybe the oil pan because the mounts broke. Just how legal are the factory replacement motor mounts?

James

Btw, I was just kidding about loading up the spare tire tray with dirt....

[Greg Amy]

I'll just go with stock trans mounts...

You mean, the ones allowed by the rules...?

...but what about the group-N or equvalant motor mounts?

You mean ones that are not allowed by the rules...?

Hey, just sayin'...

[Knestis]

My engine stayrod is about 4" long and goes from where the rear engine mount bolts to the subframe, to where the rear engine mount bolts to the block.

K

[Z3_GoCar]

You mean, the ones allowed by the rules...?


You mean ones that are not allowed by the rules...?

Hey, just sayin'...

Acutally, since hardware is free, on the trans mount I was thinking about cutting off the stud thats welded to the steel plate on either side of the hour-glass shaped block of rubber, and drilling a through hole and using a bolt to hold the mount down. The real weekness of the stock mounts is that they're basically rubber bonded between two plates and we all know what happens to rubber when its stretched...

As for the Group N parts, they're made by BMW. When I did a search on Real-OEM there's like four part numbers listed. Is one of these better than the others? It seems to me if one wasn't filled with that silicon fluid, it might be stiffer.

As for a stay rod. I don't know where I'd connect it between the motor and chassis. There doesn't seem to be a good place to do that on either the BMW motor, or the chassis. Does anyone have pictures of this on a BMW?

James

[Greg Amy]

My point, James mah man, is that the rules do not allow alternate motor mounts. At all.

It's a point that's snagged more than a few folks, myself included (I showed up at the '03 ARRC *assuming* motor mounts were free...when my good buddy Tim pointed out that the red poly motor mounts were a bit much - and I re-read the rules - I recognized my mistake).

And don't you think the "cutting off of studs, re-drilling through the mount" bit is stretching the 'hardware is free concept' just a tad...? I mean, hell, if that the case, I should be allowed to drill and through-bolt my crankcase, right? I could also use a little bit more strength in control arms, too, now that I think about it... - GA

[JoshS]

James,

My take is that if the BMW parts book (ETK, available online as realoem.com) shows a part as a valid part for your particular car, then it's a valid part for your car. I did a search and there are two different (three, but one has been superceded) part numbers for engine mounts for the 2.8L Z3. I have no idea what the difference is. What's the Group N part number?

Here's the realoem search for the Z3 2.8 roadster (yours is a CJ33, right?):
http://www.realoem.com/bmw/showparts...96&hg=11&fg=10

In my opinion, any of the three listed part numbers would have to be ruled legal ... but no others. Is one of those the Group N part?

EDIT: looks like the Group N part number is 11 81 2 224 413. Not listed for any US car. Sorry, no go.

[Z3_GoCar]

Hey Greg,

Point taken, that's why I'm asking questions before pulling the trigger and buying non-alowed parts. None of these mounts that I'm researching are urethane, they're all solid rubber that remove the silicon gel damping fluid, and are built like stock mounts.

Josh, thanks for finding the part number for the group-N mount. I performend a google search looking for that and wasn't able to come up with anything. The cars a CJ33, build date of 10/96. As for aftermarket sources for parts, how about these mounts:

http://store.bimmerworld.com/shared/...t=products.asp

James