TR2/4A Rear Crank Seal installation by: Hardy Prentice
I spent many months researching this during 25 years of racing my TR3 at
the National level. I have also built quite a number of TR2/4A race and
street motors. I have been a TR owner since 1961
Making the factory seal work is not difficult with a factory TR2/4A crank.
The factory TR4 manual images are a useful addition the TR2/3 ones,
but both factory manuals have the same CRITICAL Error.
The alignment tool drawing in both factory manuals needs to be changed to
2.818" where the tool fits inside the seal. The rest of the drawings in
the TR2/3 & TR4/A factory manuals will work. The tool seal and bearing
surfaces must be concentric. The handle is not necessary, and thick walled
tubing
can be used to save cost and weight.
I was given a tool made to the workshop manual(s) sizes, and the motor
that I
rebuilt using it leaked oil very badly running on the dyno (no G forces
involved)!
Previously, I had used the back end of a crank with the flywheel flange
sawed off, with used main brg. shells with thin paper (or thread) inside to
fill the normal bearing clearance, and .0025b to.003b feeler gauges
between
the seal and threaded crank surface.
(If you know the seal is working OK, feel free to reuse it as is,
resealing the main brg cap sides to the block recess, and avoiding any
damage to
the seal.)
1. Use the tool to check the seal's ID for size and roundness by holding
the seal ID to the
2.818b surface of the tool. Illumination behind the seal and tool help.
2. Hand work can usually make the seal fit the tool very well, or try
another seal. (I made a jig from two rear main caps to size the seals in a
lathe)
3. Install the tool in the block and the rear main cap first and carefully
check that the seal halves will fit in the block recess with the tool in
place, and the rear brg. cap torqued.
There have been seals made where the seal step OD was too big for the
block/cap ID. A problem here can be fixed by a hand file or grinder applied
to the seal step OD.
If you omit this step, you can destroy the seal and not realize it until
too late.
4. Use a small amount of silicone sealant between the seal and block where
the seal flange is bolted to the back side of the block/cap. (Go to the
next step Before the sealant sets.)
5. By hand, press the seal halfs evenly towards the centralizing tool,
then do not further move the seal halfs when you tighten the seal set screws.
Allow time for it to set.
. During final assembly, also use a small amount of silicone sealant on
the seal split line, but VERY thinly, so that it does NOT block the internal
threads of the seal.
6 Do not hurt the seal when you lay the crank in the block.
7. follow the manual(s) carefully. The rear main cap sealing felt needs
to be
soaked in something like aviation permatex, short pieces at a time, and
then be driven into the recess on each side. A B<b hex (Allen wrench) key
works well as a driver.
8. The tool can be used to align a seal with the crank in
place...Interested?
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