MTFCA Forum

Do you think that the following would work? Put O-rings on the clutch-operating shaft in the hogshead, with washers and light springs to hold them against the casing. Would it be necessary to make washers with lips on to contain the O-rings? See attached sketch. Regards, Colin.

I did exactly that senecio with the o rings as your drawing. What a pain to take out the shaft and reinstall the rivets. Unfortunately I did it with a cast iron hogshead and after all that I decided not to use it and reinstall the aluminum hogshead without the o rings. Just didn’t have the patience to go through it again. Frank

That design will starve the bushings of oil, so you will need to periodically oil them externally. And "yes" your collars should include a feature to capture the o-ring OD. in fact that capture feature must set the diametral "crush" on the o-ring as well as limit the crush that the springs would provide. O-rings never fill the gland they sit in...they are free, within a designed range, to flow...and to (usually) flow in the direction that provides a self-energising seal. Way more than you want or need, but here is a start to some o-ring education.

I would add that without machined flats inside the hog's head and good close fitting bushing/hole and round shaft, you will be limiting but not eliminating the leak, so my above warning may be moot.

See: http://www.parker.com/Literature/O-Ring ... 205700.pdf starting at page 145 for rotating shaft seal design

good luck and have fun

Scott, I think your "overthinking" this idea. I used this the last time on my O/H. The idea simply slows and helps prevent some of the oil leaks at this shaft exits. I think it was originally from Ted Aschmans collection of Tips. IMHO it does not replace that of machined and installed modern oil seals but it does provide a simple way to provide some resistance to oil flow. I think there is just enough oil seepage past it to not be of concern about wear.

Gene

I agree that my explaination perhaps appear to"overthink" it, but the poster asked if there should be a groove in the washer to capture the o-ring. Overthinking or not, the design answer is still "yes" to that question.

under the assumption that the oring is a stretch fit over the shaft (how much stretch?) and spring pressure (how much pressure?) the oring will act exactly as you stated (and I agreed...oil will still seep). In our world of Model T's, a trip to the plumbing department, an o-ring which can be forced on the shaft and a spring to push it and VIOLA leak solved.

On the other hand, an o-ring is an engineered component that can be used correctly or incorrectly. I simply wanted the OP to have the option to spend 10 minutes and design a correct solution, which sounded to me like he wanted and was capable of doing. The point of machining a groove in the washer is to limit the "smoosh" of the oring to a designed constraint, and the design page referenced will tell the OP which o-ring to buy.

Understand that I'm not trying to be contrary or nit-pick. It's just that with o-rings, you can run-what-ya-brung, or do it the way the manufacturer designed it to work. In this instance, either way will be functional, but I like to do things right (when I know there is a right way!)...and following a design (just 1 page of 250+!) manual that covers this exact use does that. I doubt that 1 in 10 readers even knew there was a design handbook for o-rings, and that all you had to do to get them to stop leaking is crank down a little harder...now they know.

How's the weather in Cali? Chilly and windy here.

The springs against the internal clutch release forks is not a good way to tension the o rings. The clutch shaft and release forks need to float free in the trans cover and not be “sprung” into one particular spot. The clutch release forks should not be allowed to drag against the clutch yoke collar. You will very likely find that equal distances from each inside side of your trans cover is unlikely to be the center of the clutch yoke collar. It is possible to get this correctly centered, however, it will involve test fitting the parts and test fitting the trans cover multiple times to get correct. Something that presses the o rings against the inside of the cover, but does not have any effect on the shaft would be a more appropriate design.

Adam, You make a very good point that I over looked. Maybe I just lucked out and got it somewhat close. Thanks for the heads up.

Scott, You're 100% right! I guess I simply didn't want some reader without the machining skills to not use this idea. I do believe that modern seals installed on the outside of the cover for the shafts is the ultimate fix. I know where there is another cheap alum '12 H/H cover that I might build up for the next rebuild on mine.

Weather here in SoCal is that very boring 70* now for several months. Somehow we'll endure it.... Not sure about the new Taxes here though..Sorry

On our Canadian sourced cars, the cast iron hogsheads are blanked off at the end away from the linkage. Is that not the case on LHD cars?

The aluminium hogsheads are open at the end. When I fit brass bushes to take out the wear in the shaft holes, the bush at the open end is left long, and a cup style welch plug is driven in to seal it. No leaks ever again from that end.

Allan from down under.