Subframe Connectors Installed! Giving Me Good...Vibrations!? - Third Generation F-Body Message Boards

FireDemonSiC · 09-01-2009, 12:28 AM

Today I had my set of UMI subframe connectors welded into the car. The car feels great. handles better and the car doesn't feel like I'ts twisting apart or about to flip over anymore. However...

From the second I pulled the car into the shop today, I noticed nothing out of the ordinary. When I went back and picked up the car and started driving it, I immediately noticed something that wasn't there before: a vibration. This vibration occurs around 1700RPM in any gear, but only when the car is moving not parked. I'm not talking a thump thump vibration, I'm talking the floorboards turn into a playstation dualshock controller vibration. It's not intense enough to the point where I think something is coming apart, but you definitely could not miss it to save your life. Is something screwed up or are the SFC's transferring vibrations that couldn't be felt before? I know one of the weld points is right where the floorboards are...

Anybody else experience this?

UMI Sales · 09-01-2009, 11:36 AM

Hello
The sub frame connectors themselves should not be the problem! I sounds like one of two things. There is a installation problem or there might be a bad bushing on the transmission. Hope that helps!
Thanks
Brad

FireDemonSiC · 09-01-2009, 11:42 AM

Quote:

Originally Posted by UMI Sales

Hello
The sub frame connectors themselves should not be the problem! I sounds like one of two things. There is a installation problem or there might be a bad bushing on the transmission. Hope that helps!
Thanks
Brad

o you are saying there is no way it is just the SFC's transferring vibrations through the floorboards? It only happens at this particular RPM, and let me add that it DOES in fact do it in Park as well.

This started the moment I picked it up from the shop. Also, there is no way it is the tranny mount It's only a 2 month old polyurethane mount from Spohn.

sid rs91 · 09-01-2009, 12:01 PM

is vibration there all the time or just at 1700RPM (i assume that it continues to vibrate after that point too)

I would think if its being transferred through connector it would start as soon as you start to move the car, its weird that it dose it in park.

could they have installed them wrong? once they are put in thats the new shape of your car.
car must be level and have suspension under load.

SystemX · 09-01-2009, 12:07 PM

Adding the SFCs probably changed the resonance frequency of your car so now it resonates with the engine/exhaust vibration at certain RPMs. My GTA developed a resonance type vibration after I put in my headers and duals. Just at certain RPMs while excellerating. Just my

FireDemonSiC · 09-01-2009, 01:30 PM

Quote:

Originally Posted by SystemX

Adding the SFCs probably changed the resonance frequency of your car so now it resonates with the engine/exhaust vibration at certain RPMs. My GTA developed a resonance type vibration after I put in my headers and duals. Just at certain RPMs while excellerating. Just my

This is the exact problem I'm having. It only vibrates at that one RPM level. Not above, or below.

1988-305-tbi · 09-01-2009, 03:53 PM

motor mounts.......

Shagwell · 09-01-2009, 04:47 PM

I'm sure the rigidity of the sfc's just multiplied/transfered the resonance/vibration.

tom86iroc · 09-01-2009, 04:56 PM

SFC could be hittin the exhaust at the bend near the cat never used UMI before but could be the problem

RED_DRAGON_85 · 09-01-2009, 05:09 PM

motor mounts.
probably what happened is that your motor mounts are shot, and the engine is where it shouldnt be, causing the exhaust to come into contact with the subframe connectors.
the shop that put my SFC's in said that they had to heat up my y-pipe and bend it slightly so it wouldnt hit the SFC...
thats my guess

FireDemonSiC · 09-01-2009, 05:25 PM

Quote:

Originally Posted by tom86iroc

SFC could be hittin the exhaust at the bend near the cat never used UMI before but could be the problem

I called and talked to the guy who did the install and he said this is exactly what happened.

l_dis_travlr · 09-01-2009, 05:35 PM

So has the situation been resolved by modifying the exhaust?