[Fot] TR3 main seal question

[Bill Babcock]

Actually you are looking at the source of many of those leaky Triumph jokes.
Scroll seals, also called Labyrinth seals, work adequately on huge steam
engines where there are scavenging pumps and oil/water separators between the
seal segments but not so well on little four bangers with a wimpy drain pipe
back to the crankcase (which has big variations in crankcase pressure).

As others have said, you can get the scroll machined off and replace the silly
thing with a somewhat compromised neoprene seal. these work better if you
increase the spring pressure by shortening the innner spring a few turns. It's
a worthwhile modification, all the steel cranks eliminate the scroll seal and
use either a split seal or an unflanged end piece.

-----Original Message-----
From: fot-bounces+billb=bnj.com at autox.team.net on behalf of Steve Belfer
Sent: Sat 8/11/2007 11:10 AM
To: Friends of Triumph
Subject: [Fot] TR3 main seal question

I've just dissassembled my spare TR3 race motor and taken the parts to a
local
machine shop and here's a silly question.  When looking at the two aluminum
half-circle's that bolt up to the block with the eight bolts (the main seal
assy.)  What the heck keeps the oil IN?  I see three or four grooves on the
crank where it fits into the seal that appear to match up with the grooves
inside the seal.  If the crank spins freely, what exactly keeps the
pressurized oil from blowing past this circular seal?

Please, no leaky triumph jokes ;)

~Steve
billb at bnj.com
Fot mailing list
Fot at autox.team.net
http://autox.team.net/mailman/listinfo/fot