possible catastrophe averted? Crankshaft damper

andrewh · Post by **andrewh** » Sat May 30, 2015 12:35 pm

I just noticed whilst the engine was running that the large diameter part of my brand new damper is running off true. I cannot get at it yet to investigate but there appears to be rubber showing at the back and on a smaller diameter part between the timing cover and the large damper. Has it let go and in the process of working its way off to the front? Seems from an initial look this maybe the problem. Anyone got a photo of a standard 3.8 damper to hand? I throw my old one away. thx

andrewh · Post by **andrewh** » Sat May 30, 2015 1:40 pm

ok, so I have had a better look at the harmonic balancer now as, I should have done before posting.

I in fact had not thrown away my old one, and my new HB is in fact the same as the old one, namely it has not given up the ghost, however, at idle the thing wobbles around and only appears to be running true as you increase the revs. Now I appreciate that this may be an optical illusion and it may still be running untrue at higher revs, but the eye may not be able to pick this up.

Question therefore must be, is this normal? I would have thought that anything you put on the crankshaft should run true for obvious reasons, but of course it may be that it is doing its job at idle and taking out any vibrations. Short of looking at another one, I have now naturally got the impression that the new made HB is not true. Compare and contrast please!!

trondvo · Post by **trondvo** » Sat May 30, 2015 3:23 pm

The original harmonic damper in my 61 is not jumping around at idle nor at revs.

Partly dismantled a '64 3.8 engine this week and was surprised how rotten the original damper (rubber) was, a third of the perimeter the rubber had separated from the base.

I'll be using the ATS damper in the engine, a little more expensive than the repros but modern construction in alu or steel.
http://www.atiracing.com/products/dampe ... jaguar.htm

andrewh · Post by **andrewh** » Sat May 30, 2015 4:13 pm

thank you for the reply. The more I think about this the more I think I have a rogue damper. Oh gee whizz, not looking forward to messing around getting that off in situ!

trondvo · Post by **trondvo** » Sat May 30, 2015 5:03 pm

Never removed one in situ but I use a large 3 arm puller, the Thor brass hammer and wrenches, as long as you get a good lock on the flywheel it should be quite straightforward, not?
I do not think you have to remove the conical sleeve, it is the one that is hardest to get a grip on.

Maybe the repros are of less quality than original Jaguar parts.

Btw, what is the correct method for "locking" the XK engine when in car? Suppose the only job that require this is when removing the front puller-harmonic damper.

In the old days I always used the gearbox and a friend on the brakes. I always try to get a flywheel lock tool these days, experience from Porsche where it is more or less std procedure.

PeterCrespin · Post by **PeterCrespin** » Sat May 30, 2015 5:15 pm

Top gear (NOT bottom) and handbrake should easily do it. Footbrake if handbrake inop. Lock the hubs if all brakes inop.

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