urethane motor mounts worth it?

[Guest Anonymous]

Any opinions on whether its worth the $70 to shell out for urethane motor mounts? Let say you need to replace them anyways (i don't... but what the hell, they'd look cooler

matt

[Guest Anonymous]

id say the best thing about urethane is its resistance to oil contamination and stiffness in applications like swaybar bushings. for motor mounts, the former would be ideal, and the latter possibly less so, at least on a street car. remember BMW engineers were and are no fools, and when you increase the stiffness of something like a motor mount, you increase the stress on everything its attached to. Are they worth it? They are pretty easy to change later, so the stock rubber ones can do the duty until you feel rich/stupid (I say that being among the more-stupid "might-as-well" parts buyers around) enough to blow the extra cash at a later time! Just some ideas/HTH!

-Rob

[Guest Anonymous]

If you go with urethane motor mounts, I'd think you'd want to consider beefing up the driver's side motor mount bracket, and perhaps the sheetmetal where teh transmission crossmember joins the body.

One rule of thumb I like to apply to potential mods, is to see whether BMW itself did such a mod to later vehicles. For example, after the 2002 BMW used larger sway bars in most models; they migrated to 4-wheel disc brakes; they made fuel injection standard; enlarged the wheels beyond 13"; etc. Clearly these things are seen as improvements in a high-performance street car; but they never went to urethane or otherwise solid motor mounts, even on the e30 M3. In fact, many later BMWs have fancy fluid-filled motor mounts to further isolate the body and passengers from motor vibrations.

Now of course many changes were made strictly for passenger comfort and the appearance of quality, so I wouldn't get fired up about fluid-filled motor mounts (you know what those things cost!?!). But I'm sure there are enough drawbacks to solid motor mounts that they aren't worth doing unless you're having a real problem with weak motor mounts on a race car.

Mike

[Guest Anonymous]

a torque strut brace. (correct name??) This is a short horizontal strut with a rubber bushing at each end. One end gets attached to the engine block as high as possible, and the other end gets attached to the inner fender/strut. This reduces torque 'twisting' of the engine on its mounts when you punch the throttle and lift it off quickly, but it still provides good isolation from the engine to chassis.

I think there is a piece off another model of BMW that can be adapted. I saw one in a 325i once at a wrecking yard. You can also find them on other makes of cars and you could adapt those.

What about just using HD rubber mounts?

Gil

72 Tii

[Guest Anonymous]

Thanks for the input guys. I was placing an order with Ireland anyways.. and my usual way of doing things are to order everything i'm going to need (from that given vendor) in advance..so its just one big shipment. anyways, i'll forget about the urethane, but

are the drivers side brackets weak? is this something I should beef up with some bracing before i drop the m20 in? if so, anyone have pics of what they have done?

thanks

matt

[Guest Anonymous]

I've not had a problem myself, nor have I done any strenghtening of the mount, but I hear tell that if you put in a big motor and push it hard, sooner or later you could crack the "ears" that form the driver's side bracket mount. The bracket is formed of open sheetmetal stampings. The treatment I've seen involves "boxing" in the open stampings by cutting sheetmetal and welding over the open sides. I've seen pix of this method posted somewhere on the web; look at the racing tech sites, maybe Pat Allen, or Tomi Heinonen of Goodfellas, knows more about this.

Mike