Dartht33bagger

When I did my engine swap last May, I put Energy Suspension polyurethane motor mounts and transmission mount in my car. Ever since then I've been having vibration issues around the 1800-2000rpm mark in any gear. For the longest time I thought it was because I wasn't running the braces on the alternator and the A/C compressor. Well I put those braces back on last weekend and while it did help, there are still more vibrations than I'd like.

When coasting, I can feel a cyclical 3 step vibration in the steering wheel. At the 1800-2000rpm range, I get a mild vibration. Higher rpms can sometimes be fine while other times it vibrates. After doing some reading tonight, it looks like the cause of my vibration issues may be coming from my motor and transmission mounts. Is there anyway to make this better without having to switch back to rubber mounts? Putting in the motor mounts the first time with the engine bay open was a nightmare. I can't imagine trying to do it again with the car fully together....

Drew

iTrader: (58)

Have you looked at the plentiful threads about the ES transmission mount being too tall? Removing the preload plate helps, but ultimately it's probably still going to transmit vibes.
It's easy enough to change the trans mount, it'd probably be worth swapping to a stock mount to see if the shakes go away.

When you changed the engine, did you pay attention to which engine mount bracket was on the left/right? Because they're different from each other.

You might try adjusting the trans crossmember and mount. All the holes are slotted, and sometimes its possible to get things far enough out to get vibes.

There is also a chance of creating vibes by reinstalling the drive shaft 180* off. How recently have you checked the U-joints?

skinny z

While this may not be your particular issue, it might be worth looking in to.
For the record, I have the Energy Suspension transmission mount and new (but traditional rubber) engine mounts.
The vibration I had could be described the same as you have described yours.

https://www.thirdgen.org/forums/tran...vibration.html

Dartht33bagger

@Draw

I did some searching last night and only came across a few threads on it. Maybe my search terms weren't correct. We installed in the brackets in the wrong order the first time and couldn't get the engine to fit. We switched them and were able to get the engine in so I imagine they are in the right order now. It is possible the drive shaft is 180* off since I changed out the front seal on my rear end a few months back. I will check that.

@Skinny

Now that sounds promising. I've always been wondering if it is flexplate to torque converter related. This is something I'm definitely going to look into.

skinny z

I mentioned in my other thread that it's a service procedure in the GM Camaro manual. Funny how (for me) it was overlooked for so long by so many. Including me.

Dartht33bagger

Following up on this: Skinny Z's method worked! I now have significantly less vibration and the car feels like it did before the engine swap. No need to swap out the engine or transmission mounts. Thanks a lot!

GeneralDisorder

iTrader: (1)

I have experienced this as well. I bought the car (86 Trans Am) with this exact vibration. I decoupled the torque converter from the flex plate trying to isolate the vibration and when I hooked it back up it was gone. I ran across this thread and now I know why. I thought it could have been due to movement between the two because there was fretting around the bolts. Nice to know what the actual cause is. A valuable lesson for sure. Mine went from super annoying and obvious to completely gone.

Strangely I just changed out the transmission and didn't mark anything in the process (thinking the fretted bolt situation to blame) and did not have the vibration afterwards. Guess I just got lucky like you did on the trans swap.

Rick