I just installed a new aftermarket (siemens) blower motor in my 99 Bonneville SE and it seems to run fine, however on high I can feel vibration in the steering wheel and gas pedal, which is kind of frustrating. Any other speed is fine, no vibration felt. Is this just due to the fact that I went with aftermarket instead of oem, or perhaps should I back the mounting screws out a bit so the dampening effect of the rubber grommets holding the motor in might isolate the vibration a bit?

I did also notice that one of the cage fins looked slightly cracked, but didnt look like anything that would effect performance of the blower. Please share your experiences......Thanks

sounds like at higher speeds it becomes off balance. that would be the only thing i could think of that would make a vibration. kinda like having your wheels not ballanced properly will cause a nasty vibration

If one of those is fins is broken it could be very possible that it would throw it out of balance

I actually torqued the screws down a bit and it smoothed things out considerably. I think sometimes i'm overly picky and we all know that new parts can act differently. Plus an aftermarket part at half the price of oem probably cannot be expected to perform the same. i'll let the part run in for a bit and see if Im ok with it. Otherwise I'll put an AC delco blower in. Thanks for the suggestions...

Your welcome glad to hear you got it fixed some