Anyone else's motor suffer from resonance? I have one at 60ish that disappears at 70....most annoying.

yeah its normally me after a few beers

its most likely things working there way loose..

Id check the whole car over..

or I could be totally wrong and its just your floor etc

I've had a good look around, nothing obvious.

Wonder if it's the ali side panels?

Good reason to use sikaflex in the first place.....

Can you push wedges of cardboard or foam inbetween the chassis rail and the panel side to stop it? If so you could try opening the gap up gently and squirting some sika in....

Had a very similar problem to this a while back and took us a long time to work out what it was.

WE had bolts winding themselves out and all sorts and in the end tracked it down to a work propshaft spline.

The prop was too short and although initially prob looked fine the splines wore and to the universal joint was able to whip round and cause a rotational vibration (hense the bolts coming out)

The problem started in a similar 60/70 res and then went away when faster.

Worth a check!!

When I'm driving along in 4th gear with the speedo reading exactly 50, I can't see anything in my centre mirror because it vibrates at a very high frequency. At all other speeds and in all other gears it's fine.
Must be a natural pitch thing.

David

Sometimes your exhaust can will resonate and transmit vibration at a surprisingly high level. Repacking will help if that is the case.

It may be the rear bulkhead too... that's why we put some cheapish carpet onto it.

Steve

All part of car development really!

I bought my kit part built but all they had done was put the ali panels on. They didn't use a sealer as it was intended for racing and wanted the panels easy to remove. I had loats of resonances in the panels from various sources such as the exhaust can, GBX touching the chassis and general engine resonances.

So what I did was run a bead of sealer around the interfaces between the ali and chassis. I also put cut hoses on the round chassis members or rubber wedges in any gaps. I repacked the exhaust can but remember not too tightly and used a rubber engine mount between it and the body.

Since then i've changed the engine and found my shiny Fidanza flywheel was out of balance which didn't help either. Anyway lots of little things can help.

mine used to hum badly at 6k revs. I expected that though as the engine was solidly mounted.

Yes, mine is solid mounted - doesn't help.