How do you know when you need new mounts?

[rreimund]

Hi all,

I've been experiencing some clunking in the drivetrain when I shift hard, or let off the gas quickly. It sounds like it might be some motor or tranny mounts allowing too much movement. If I drive like grandma, it's fine, but if I'm a little more agressive it can come up.. (but not always.)

What's the decisive test for determining if a mount needs to be replaced, what's the allowable deflection for a good mount? Where is it measured if that's how it's determined?


Thanks in advance.

- Rick

[mattyb]

you can go to your indy and get him to check or you can get under it and look. jack up the engine, not sure about 535 where but on 540 i just used the front of the engine with a block of wood. lift and watch the mounts, you will either see the engine start lifting from the mounts or not. theres not really in between. tranny mounts just get under there and look you will see if thay are stuffed or not. could be ripped or torn, big kriss knows plenty about the tranny mounts.

[Shaun]

you can go to your indy and get him to check or you can get under it and look. jack up the engine, not sure about 535 where but on 540 i just used the front of the engine with a block of wood. lift and watch the mounts, you will either see the engine start lifting from the mounts or not. theres not really in between. tranny mounts just get under there and look you will see if thay are stuffed or not. could be ripped or torn, big kriss knows plenty about the tranny mounts.

Here's what my tranny mounts looked like before I replaced them with UUC Street mounts with the TME cup:

http://black.plague.org/pictures/bmw/repair_tmount1.jpg

matty's right, getting under the car and doing a visual inspection is pretty easy for the tranny mounts. I need to check my engine mounts though :(

[DanH]

I would take a look at the driveshaft center bearing($30) and the flex disc (guibo $?) between the tranny and driveshaft. These seem to be the most common causes for clunking in the drivetrain. The exhaust system and driveshaft have to be removed to fix these.

You can check if there is any side-to-side play in the driveshaft before taking everything apart.

Both parts can be had cheaper than engine mounts($38-50 each), but tranny mounts are only about $7-12 each.

If you don't know when these wear parts were last changed, then replacing all of these parts at once would be less labor, since they are all going to wear out at some point and a lot of the labor overlaps for each part. (I'd be sure to test the engine mounts first though, since they are more $.)


Hi all,

I've been experiencing some clunking in the drivetrain when I shift hard, or let off the gas quickly. It sounds like it might be some motor or tranny mounts allowing too much movement. If I drive like grandma, it's fine, but if I'm a little more agressive it can come up.. (but not always.)

What's the decisive test for determining if a mount needs to be replaced, what's the allowable deflection for a good mount? Where is it measured if that's how it's determined?


Thanks in advance.

- Rick

[rreimund]

Good stuff guys.. thanks..

Has anyone used the upgraded 320i tranny mounts that Bruno mentioned some time ago?