Mandrels 'r us !

[Superaquarama]

Ok, my mate has now made a mandrel for the rear oil seal. I'll comment later on the exact diameters involved, but the part for the oil seal seems to be an absolutely exact fit when the scroll seal is offered up, i.e. there's no clearance or play whatsoever.

 

Is this correct and maybe the crank will grind off a tiny fraction of the ali until it's happy, or should we take a tiny bit more off the mandrel to leave a minute amount of clearance ? I'm assuming that, even with new shells and a reground crank, there will be a minuscule amount of movement ?

 

Thanks,

 

Anthony

Edited January 26, 2013 by Superaquarama

[Kiwifrog]

Hi Anthony

 

when I made mine to Christians domensions it to was a tight fit no movement whatsoever, I did slightly enlongate the seal mounting holes as per the instructions to get the bast fit possible, when I installed the scroll seal along with Christians lip seal it fitted perfectly with no sign of it touching the crank when it was turned.

 

The mandril is larger than the scroll on the crank. When you fit the crank you can always check it by turning it round a couple of times with the seal in place to make sure you do not have a problem, always a good idea to trial fit everything before final assembly.

 

My engine has only run a short while but there is no sign of any leak from the seal.

 

Cheers

 

Alan

[Superaquarama]

Thanks, Alan. Well, oil seal now fitted and crank in place, so fingers crossed that the thing doesn't leak !

 

Now,about the mandrel sizes, just for the record if anyone's doing a search on the subject.

 

Eric, my mate with the lathe, and myself both agree with what Christian says, in that the workshop manual mandrel size is too small. Independently from Christian, we ended up with virtually the same measurement, i.e. Chris had 71.57 mm and we got to 71,58 mm. Contrast this with the manual which says 71.679 mm - plenty of room for oil to leak out of that 0.1 mm difference !

 

We also noted some digital caliper error. Both Eric's and mine seemed to read about 0.08 mm less than the above, compared with the old fashioned vernier - more fiddly to read but more accurate !