John Eales crank damper, oil seal journal eccentricity
Posted: Sun Aug 10, 2025 10:14 pm
Hi all,
I am building a 5L Wildcat engine for my Chimaera. I was having problems with valve gear and springs. Got that sorted now.
Just one problem after another with this build though, which I expect, but some are problems that should not occur.
Long version --
I bought a performance crank damper from John Eales. The rubber in the old damper was starting to show signs of degradation. The JE item is slightly larger than the standard item, so I had to slightly relieve the timing pointer a bit to get it to clear. It's an interim serp front cover.
I had timing marks machined on the damper, and a hole for a roll pin for the pulley.
I fitted a trigger wheel this weekend. I have had to space it off the damper a bit, so I had a spacer machined to fit between the damper and trigger wheel. The trigger wheel no longer locates on the damper in this configuration, so I had an alignment tool made that centres on the oil seal journal, and welded the trigger wheel to the spacer. Worked well, were it not for for the following.
I was measuring up to make a bracket for the sensor today, and I noticed that the trigger wheel has runout, despite my alignment collar. Upon investigation...
Short version --
... it turns out that the oil seal journal on the JE damper has 17 thou of run out. Runout of the outer part of the damper is about 2 thou, so the bore is concentric with the damper, but the seal journal has been machined off centre.
My question is, how much run out on the oil seal journal is permissible? Close to half a mm seems way too much to me.
I am building a 5L Wildcat engine for my Chimaera. I was having problems with valve gear and springs. Got that sorted now.
Just one problem after another with this build though, which I expect, but some are problems that should not occur.
Long version --
I bought a performance crank damper from John Eales. The rubber in the old damper was starting to show signs of degradation. The JE item is slightly larger than the standard item, so I had to slightly relieve the timing pointer a bit to get it to clear. It's an interim serp front cover.
I had timing marks machined on the damper, and a hole for a roll pin for the pulley.
I fitted a trigger wheel this weekend. I have had to space it off the damper a bit, so I had a spacer machined to fit between the damper and trigger wheel. The trigger wheel no longer locates on the damper in this configuration, so I had an alignment tool made that centres on the oil seal journal, and welded the trigger wheel to the spacer. Worked well, were it not for for the following.
I was measuring up to make a bracket for the sensor today, and I noticed that the trigger wheel has runout, despite my alignment collar. Upon investigation...
Short version --
... it turns out that the oil seal journal on the JE damper has 17 thou of run out. Runout of the outer part of the damper is about 2 thou, so the bore is concentric with the damper, but the seal journal has been machined off centre.
My question is, how much run out on the oil seal journal is permissible? Close to half a mm seems way too much to me.