1950-1977 FL fork cap breathers

[neilw]

I'm reassembling my 1959 FLH that has been in a basket for 15 years ,I was just reading the HD service manual ,and it says to inspect the fork cap breathers if oil comes out of them ,or if the original snubbibg action of the forks has been lost .In either case it tells us how to drill,pry or use a tap to get the breather out to replace it .I am wondering about how it is suposed to be inspected. I ran across this about a week ago and since the bike only has 27000 miles on it ,the breathers are probably good .I wanted something to do on the bike so I had been reading the manual ,looking for just such a thing .I asked several poeple about these and none of them even new they were there .I started asking on different HD forums on the internet ,and found no one knew the answer .I have asked this on at least 8 forums .Lot of speculation ,but so far no expert has answered ..I'm am now making it my mission in life to find out about these breathers .I have in total 4 caps with breathers in them (2 off a 61 pan basket case ) I can't blow through any of them of **** air through them either .I shot air into either ends and nothing seemed to come out the other hole .I sprayed them with loads of WD-40 still the same ..I noticed in the parts book it shows they didn't start using them until 1950,but they used the glide starting in 1949..Could this be a clue ? In late 77 they stoped using them ,but my book doesn't show them being replaced with any other breathers ..I'm wondering if they could be 2 way pressure releif valves . they stop oil from blowing out .( the book tells us if the forks are over filled oil can come out of these ) and they give the forks the right amount of snubbing action ( HD's term) .One guy on the net pryed one out of a fork cap he had laying around and said there was a little plastic looking ring in there ,and mentioned a plunger ,but not how they fit together or anything ..
Some folks told me not to worry if they work or not ,and that it wouldn't make a difference .I of coarse disagree ,there in there for a good reason ..Regardless of whether or not I need them ,I want to find out how the HD mechanics checked them and ,there history and so on ..At this point I'm more interested in all the trivia attacheched to them and there use than if I need them ..Between the 2 dealers in town here they have 5 instock .They are now obsolete .and $20.00can. each, I may just buy a pair to see what they look like .
BTW this mystery is what drove me to searching for HD forums ,and I ran across you folks ..So whatever I find out I'm glad I discovered AMCA .I'm going to have lots more questions ..
Neil

[Rub]

Neil, The breather valves are a spring loaded one way valve intended to keep the forks from pressurizing and becoming solid or having the seals blow out. Any mechanism that has oil in it that is heated through use and friction needs some way to disperse the resulting expansion and pressure build up. There are engine breathers, transmission breathers, differential breathers, oil tank froth towers, etc, on all manner of vehicles. The stack of notched cups on the bottom of the fork lower cap are air/oil separators. The breather merely allows the pressure to escape in a controlled manner. The '49 forks did not originally have breathers and blown seals were commonplace. There was a dealer installed kit to take care of it, but it wasn't great either. The breather cured the problems and was used all the way up to the Showa built forks. I have only seen a few replaced in many years of messing with these front ends, usually only on old rusty top caps. Air should escape from the top if blown into from the bottom but not vice-versa. Robbie

[neilw]

Robbie ,You left me in shock ,after my week and a half of searching and getting some half baked answeres (except the guy who took one apart) you gave me so much information I'm still trying to comprehend it all ..
You know ,all my life (I'm 60 ) I valued having access to correct information , You caugt me off gaurd ,I have nothing further to ask .You really made my day , Thank you for such a clear and logical explanation ,and history too.. I couldn't ask for more ..
Neil

[Ohio-Rider]

Welcome aboard neilw.

There is indeed a great wealth of knowledge at our disposal here. Enjoy, and please feel free to post often. Got any photos of that 59.? Sounds like a fun project.

It was furtunate that Robbie was here when you asked your question. He has much knowledge about these old machines as do many of our members. -Steve

[MJW]

Maybe someone has an idea why my front end is so stiff, I took the tubes out of the trees to dissasemble them to try and figure out why they are so stiff, inside I found about eight ounces of oil,(about an ounce and a half too much). With the springs removed the sliders seem to slide up and down but with some effort. Should they slide easily? I re-assembled them with 6 1/2 oz of type E fork oil and they work a little better but still too stiff. I've had lots of Showa forks apart but no early forks. I'm not really sure what year they are, the drum is on the left but it has the 67 up drum and no hole drilled in fork stem for a lock. They are on a wishbone frame with a 51 pan engine and tranny. I'm in the process of breakin' in the motor and trans. Shure would be nice if I could get this fixed! Thanks for any ideas....Mike

[motorhead1]

1) You should be using type 'B'.
2) Did you disassemble and inspect the damper assemblies? They could be binding.

[MJW]

I guess I was hesitant to dissasemble the dampeners, I've read a few posts about how easy it is to cause a leak where the dampener bolts down in the bottom of the slider, I'll wait till I can source some new tubes and change back from 2" over to stock lenght. Mike

[neilw]

MJW, I just took my tubes apart from a 1961 FLH ,unlike yours mine slide easily .If I hold the lower leg upside down, the tube would slide out slowly ,(under it's own weight) Same thing when putting the tube back into the lower leg,if I start the tube in, then hold it vertically it will slowly slide down into the lower leg. There is resistance and they slide slowly ,not with a dropping motion.
I measured the spring ,which is 19 3/4 inches long and 1 1/4 od
Other than whats been allready said I have no idea ,unless you have some wrong part in there .
Neil

[MJW]

Thanks for the info neilw, stock tubes and springs are on my list, It's already been 92 degrees here in Mpls. way too hot for breaking in my new motor, so it's a good time to fix the stiff fork! Mike