Harmonic vibrations - your advice please

[canadianminimk1]

Greetings from Canada, well just yesterday I spent about 5 hours chasing a similar sounding resonance/vibration at approx the same rpm range on my 66 Cooper S. The car was awful to drive.
I had just refitted my engine after a camshaft swap and general clean up. So after checking the exhaust, the shifter extension mount and steady bar and mountings I decided to fit the old engine mounts back into the car. (I forgot to mention I had fitted new ones when the engine was out)
This is quite a fiddly task when the engine is in the car but I managed to do it and my resonance/vibration is completely gone.
Having a closer look at the new mounts I stuck one in a vise to see just how hard they are by trying to flex one with a pry bar and they seem almost solid! I bought them about a year ago and kept them for an occasion when the engine was out for repair. The old ones weren't terrible I just thought
it made sense to fit new ones when the lump was out.
So, I am not sure if these new mounts are defective or just made of too stiff of a material or perhaps they are for a rally car that is subject to massive strain but I ordered them just as regular replacement mounts.
Anyway, I hope this is of some help to you and that you find the cause of your resonance/vibration.

Cheers,

Andrew

[AndyPen]

I certainly experienced quite a difference in my Cosworth when I fitted competition engine mounts - so you might be on to something there

[Jt850]

Hmmm, that’s really interesting. It has new ones, not sure where I bought them, but they have the captive nuts. The original ones were shagged, so I needed new ones, but I will definitely change them. Does anyone anyone have a preference of where to get good ones?

[Jt850]

The whole lot can be seen here:
https://www.youtube.com/watch?v=ow5cGV7bXCw

Wow, thanks smithyrc30, much appreciated. What I’d give to spend a day with him!
Need to get a viscous balancer and belt driven camshaft kit - and new engine mounts

[Jt850]

Could it be that the Crank Damper has failed ?

They are two pieces and can fail, that rubber is bloody old now......for sake of £90, might be wort replacing it, cant do any harm.

http://www.minispares.com/product/Class ... o%20search

Thanks Exminiman I think I’ll replace that too while I’m doing the engine mount.

[Exminiman]

Could it be that the Crank Damper has failed ?

They are two pieces and can fail, that rubber is bloody old now......for sake of £90, might be wort replacing it, cant do any harm.

http://www.minispares.com/product/Class ... o%20search

Thanks Exminiman I think I’ll replace that too while I’m doing the engine mount.

please check I got the right part number, might be worth a conversation with MS or where ever you buy from

[Spider]

Could it be that the Crank Damper has failed ?

They are two pieces and can fail, that rubber is bloody old now......for sake of £90, might be wort replacing it, cant do any harm.

http://www.minispares.com/product/Class ... o%20search

Thanks Exminiman I think I’ll replace that too while I’m doing the engine mount.

please check I got the right part number, might be worth a conversation with MS or where ever you buy from

I'm not sure if these have been sorted out, but they were parting company. The 'rubber' used in them appears to be Polyurethane, used in a Damper, I doubt it has the right characteristics for the Damper to be effective.

[Jt850]

I think I'll go a Romac balancer https://outlawspeed.com.au/shop/ro0239 and new engine mounts, see if that makes a difference.

[Jt850]

Replaced the balancer and the engine mount on that side. About a 40% improvement- yay! Will do the clutch-side mount at some stage, but consensus is it was the balancer that made the difference. Fitting the other mount might give just a little less vibration into the body though, so worth doing. Any tips on doing that one? Never had to do it with engine fitted.

[minibitz]

Clutch side is the easier side to do....once you get the bolts out of the clutch housing to remove it.

I undo the mount, jack the side of the motor up then put a block between the bottom of the transfer case and subframe. Block needs to be carefully positioned not to get in the way of the cover bolts. Then it's just a case of undoing the cover bolts, remove, swap the mount then refit. I use a ratchet spanner with a swivel head to access the awkward bolts. Sometimes you get lucky and the bolts come lose as soon as they are cracked, other times they are buggers and need spannering all the way out.

Worst one I did some numpty had forced in M8 bolts.

I use the genuine Minispares mounts which are noticeably softer than their non genuine type although the fit is identical. You can actually feel the give in the rubber with your fingers when comparing the two types. The rivnut type captive mounts are only good for the bin in my opinion.

[Jt850]

I use the genuine Minispares mounts which are noticeably softer than their non genuine type although the fit is identical. You can actually feel the give in the rubber with your fingers when comparing the two types. The rivnut type captive mounts are only good for the bin in my opinion.

Thanks minibitz, I'll definitely change the clutch side one too. Hopefully that will make that extra bit of difference.

It's such a cracking engine, sooo much torque - easily pulls from 50kh/h to 140km/h in top gear no problem. Have I said how much I love it? Maybe not, so I should