The problem with the original seals is that there is excessive clearance
between the crankshaft scroll and the alluminum housing. The factory setup
gives .012" clearance on the diameter. That is just to much. We have been
"remanufacturing " the seal housing and bringing the clearance down to .006"
on the diameter. That works great on a tight engine. There is vitually no
leakage unless the engine is reved over 6,000 rpm. At reves over 6,000 the
crank begins to flex and it allows a little oil out. For street engines and
mild race engines this "blueprinted" seal is the ticket as far as I am
concerned.
For a high RPM race engine we weld up the threaded area and have it
remachined to the original major diameter of the threads and then remachine
the original seal holder to use a Chrysler 383 cu in engine 2 piece rubber
lip seal. This setup does not leak a drop at engine speed over 7200 rpm.
With either of this seal arrangement, concentricity is very iimportant.
We will not build and engine using the "Split one piece seal" as sold by
Moss. I have tried them 4 times, each time it has taken 5 or 6 hours or more
of setup to get the alloy seal holders to fit the block correctly and the
seals have still leaked at least a little, sometimes a lot!.
Greg Solow
----- Original Message -----
From: "Randall Young" <ryoung@navcomtech.com>
To: "'Friends of Triumph'" <fot@autox.team.net>
Sent: Monday, August 13, 2007 2:42 PM
Subject: Re: [Fot] TR3 main seal question
>> If the crank spins freely, what exactly keeps the
>> pressurized oil from blowing past this circular seal?
>
> A minor point, the oil should not be pressurized by the time it reaches
> that
> seal. There is a cavity between the seal & bearing, with a drain hole
> back
> into the sump. Some folks have theorized that the hole isn't big enough,
> and drilled additional holes, but I haven't seen the need myself.
>
> Also note that some of the rubber seal kits on the market have the wrong
> instructions as to how small to grind the crank.
>
> Randall
> (Tedious but unavoidable disclaimer follows)
>
>
>
>
>
>
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