The instructions that come with the seal call for the crank to be
ground to 2.500". In many engine builds using this dimension, Jack
and I fought leaking rear seals. Jack eventually discovered that if
he had the crank turned to 2.525" rather than 2.500" that he had much
better luck in getting the rear seal to work properly. He also
shortened the spring supplied with the kit to 8".
Prior to using the larger crank diameter, his fix was to cut a little
off of one edge of the seal. This is a very inexact fix, and the
larger crank diameter worked much better for us.
Since my crank is ground to the smaller diameter, I don't have much
recent experience with the 2.525" diameter. We never had a problem
with the seal "grooving" the crank.
I've had one rebuild out of probably 4 where I got the rear main to
seal properly. I hope for the best every year.
Jack wrote up a series of engine building tips, and I've made it
available to everyone here:
http://www.tonydrews.com/uncle_jacks_engine_building_tips.htm
The larger crank diameter is one of the tips.
- Tony Drews
At 02:01 AM 10/5/2010, Alexandre Camoletti wrote:
>I have to admit I am getting lost here.
>My supplier (Simon, from TR Enterprises) in the UK, says crank must be
>ground down to 2.5'', ie 63.5mm, anything more puts too much pressure on the
>lip seal and it will then groove the crank.
>Simon told me it is originally a Land Rover seal and the size is exactly
>2.5'', which is logical as it was originally an English fitment.
>Moss' leaflet gives a tolerance of +0.1mm, - 0.0 mm. So the minimum for them
>is 63.5.
>But to go from 63.5 or 63.6 to 64.135 (2.525'') seems a lot more.
>Tony, you mean it leaks if crank is ground to 63.5mm? What is your
>experience with this dimension?
>Thank you !
>Cheers
>Alexandre
>
>-----Message d'origine-----
>De : fot-bounces@autox.team.net [mailto:fot-bounces@autox.team.net] De la
>part de Tony Drews
>Envoyi : mardi 5 octobre 2010 07:55
>@ : Dan Cronin; Friends of Triumph Triumph
>Objet : Re: [Fot] Crank--Rear Main / Scroll
>
>For the aftermarket lip seal like is sold by Moss, British Parts Northwest,
>and BFE, the correct crank diameter is 2.525". Despite explicit instruction
>to use that dimension, my Crower crank was turned to 2.500", as the seal
>instructions indicate it should be (incorrectly). I've managed to make it
>seal by using a very sharp knife to cut a little bit off of the edge of the
>seal. Some rebuilds that works better than others. I also shorten the
>spring to a bit under 8" so there's a fair amount of spring pressure on the
>seal.
>
>The seal the Christian Marx developed, marketed in the USA by Joe Alexander
>is for stock cranks that have the scroll seal.
>
>- Tony Drews
>
>At 01:02 PM 10/4/2010, Dan Cronin wrote:
> >Listers
> >Some time back in mid 07 I purchased a Crower E4340 Billet Steel Crank
> >for my TR motor build which I am just now getting around to......had
> >the rear lip milled to the 63.5mm (2.5") that was the collective
> >thought (manual and instructions for the improved rear main lip oil
> >seal) and now find that most think this was in error! Am I right that
> >now the proper size for the seal is 71.57mm (2.8"), and if so what is
> >one to do if he has the "old" dim.? Can the journal be built up by
> >hard chroming and them re-milled to size? What other options can you
> >think of that would permit successful use of the 2.5" scroll with the lip
>seal? What have others done to surmount this problem?
> >Thanks, Dan C.
> >_
_______________________________________________
fot@autox.team.net
http://www.fot-racing.com
Donate: http://www.team.net/donate.html
Archive: http://www.team.net/archive
Forums: http://www.team.net/forums
|