My car is a vibrator... sometimes.

[krappy]

Full disclosure - I have Vibratechnics/Ktec engine mounts and Powerflex dogbone bushes in my 172 and with those it had a bit of increased vibration over the oem mounts but tbh not much (I was fairly careful with the installation )

Now, I did a trackday last month and the car was great, however since then I have been experiencing an intermittent increase in vibration. It's not a constant thing, sometimes the car is fine and feels great and other times there is noticeably more vibration and the car also feels just a bit less responsive. Exhaust seems to be a bit louder as well. The increased vibration seems to be more noticeable after driving for a while/when starting the car is warmed up.

Now initially I was thinking perhaps exhaust or engine mounts? I replaced the rear exhaust mount for a new oem as while on the trackday I could here an occasional knocking from the rear and the rear mount looked past it's best. Central hanger looks ok so haven't replaced that. I have checked both the upper engine/gearbox mounts and both look good - have less than 3000miles on them - no nuts/bolts have loosened off and I have confirmed that they are torqued to the correct settings. No cracks to the legs of the battery tray either.

Didn't get a chance to get under the car and check the dogbone, however that has similar low miles on it since installation as well.

Now the increased vibration isn't ridiculous - just definitely more noticeable, as is the exhaust noise. Anyone have any ideas? Thinking perhaps could be exhaust related?

 

[MicKPM]

Have you checked to see if any of the mounts have moved? If the engine isn't bolted in straight it will cause issues.

 

[krappy]

Thanks for the reply Mick. Yes I should've said that I looked for any signs that the upper engine/gearbox mounts had shifted but I couldn't see any (no marks etc). All bolts etc were tight.

 

[debussetti]

I've not got uprated engine mounts except the Poly-flex dogbone, and I get the same thing.

Some days the car just never gets to it's hot-map (Dan @ 519 recently did the thermostat) and when I'm stopped in traffic I get a huge amount of vibration.

Next things to try are cleaning the TDC (I have second start) and maybe a temp sensor.

 

[krappy]

Funnily enough I cleaned the TDC sensor and since then the car has been running better - not sure if coincidence or not...

 

[llgsimpson]

I had this once, took me ages to figure out that the exhaust mount was actually hitting the car only slightly causing a vibration and the sound to travel into the inside, It was louder when moving off or in idle when there is the most movement in the exhaust. solved it by putting a little bit of rubber against the mount, was dead quiet after that either way for vibration somethings loose/moving right?