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MG Midget and Sprite Technical - 1275 crank damper

So (slow) new fast engine build and here is the problem.

The original damper has a big chip in the rim (right in the pic)where it clamps the rubber damping material.
So I think that is a good reason not to use it.

The left one was one in my spares selection but I think it came from a 998 mini.
It also has an extra ring in it (se next posts for more pics) and is a lot more narrow.

Is it suitable for a high spec 1275 build?
It would be balanced of course before.

Or should I just take my loss and get the singing and dancing shiny new MED damper.....

Onno Könemann

nr 2

Onno Könemann

nr3

Onno Könemann

Hey onno

The one on the left looks likr the rubber has seen better days... Id be tempted to go with the one on the right....maybe even chuck it in a lathe and turn it down to save an american pound or 2 off the rotating mass


Im just commenting based on what i can see on my phone

Good luck

Prop
Prop

The one on the left looks OK to me. I might be tempted to remove the ring from the back of it, as it looks a bit bent.
Dave O'Neill 2

Jep that second flange is bent but just held on with 3 rivets.

So no thoughts about using a 998 damper on a 1275???
Onno Könemann

Ive been thinking about that... I cant see any issue with the 998, on the 1275... But we are talking my personal opinion.

Im thinking aftermarket pulleys are 1 size fits all for the A series engine

Prop


Prop

The dampers are tuned to eliminate some specific frequency of torsional vibration of the crankshaft assembly, which includes the flywheel and clutch. On those grounds, you should use the damper that matches everything else. Any change in rotating masses (eg, flywheel) theoretically calls for adjustments to the damper mass, but you are unlikely to find anyone who can tell you how much or in which way, so best to just leave it as is. There is a lot of BS on the subject, generally to the effect that somebody has run without a damper, or modified it, with no bad effect, but the failures caused are not immediate, rather taking the form of long term two piece cranks.

The chip, in and of itself, is not a fail, so long as there are no other cracks, and the rubber is good. You might correct the imbalance of the missing piece by grinding a corresponding bit just opposite.

It is wise to index mark the inner and outer pieces permanently, so that if the outer starts to walk around on the rubber you will know, as that is the indicator of impending disaster.

FRM
FR Millmore

This thread was discussed between 24/10/2011 and 26/10/2011

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