[TR] Leaking rear seal on my TR3A's engine

[J.C. Hassall]

I also bought the Moss seal kit which had the incorrect scroll dimension.
Yep, it leaked.  The fix was to shorten the seal spring by (as I recall)
1/2" and very carefully trim the seal faces slightly to ensure they were
perfectly parallel.  It was a fiddly process but worked.  Thanks to Tony
Drews (FoT racer) for the tip.  For exact dimensions, check Tony's web page
(https://tonydrews.com/uncle_jacks_engine_building_tips.htm#Crank).

hth

jim

On Wed, Feb 12, 2025 at 10:50 AM Dave MacKay <dave at mdmackay.ca> wrote:

> I followed the recent exchange about “TR Rear Crank Seal Rope?” with
> interest and corresponded with all who replied to the OP. That has me
> thinking about how I might address my situation.
>
> In 2008, the engine in my TR3A was rebuilt. As part of that effort an OIL
> SEAL CONVERSION KIT was fitted. The conversion required that the scroll on
> the crankshaft be ground down. It has always leaked.
>
> I had convinced myself that fixing the leak would be too much trouble and
> too expensive to be worth doing. I envisioned having to replace the
> crankshaft and then using a more modern conversion (Moss 837-160). I
> wanted to check with the list to see if that’s the case or not.
>
> I believe --- but am not certain --- that the conversion was sourced from
> Moss (perhaps p/n 837-006). I am aware that incorrect instructions were
> provided with some of the conversion kits so that the crankshafts were
> ground too small. I don’t know if that’s the case with my conversion: the
> crank may have been ground to the correct dimensions, or it might not have
> been.
>
> I have three questions:
>
> 1) Is there a way to check the crankshaft dimensions to see what it has
> been ground to that doesn’t require pulling the engine? I’d like to know
> if the crank had to ground to the correct dimensions or not.
>
> 2) If the crankshaft was ground to the wrong dimensions, is there a way to
> fix it (e.g., special seal) short of replacing the crankshaft? Replacement
> crankshafts are scarce and quite expensive (>USD$1600).
>
> 3) If the crankshaft was ground to the correct dimensions, what have
> others done to keep that oil seal conversion from leaking?
>
> I’d welcome any input from those on this list.
>
> Dave MacKay
> 1960 Triumph TR3A, s/n 68639L
> near Toronto, Canada
> ** triumphs at autox.team.net **
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-- 
jim  W4BEA
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