Fork Oil Seals. Which Way Up?

[LJ.]

Lots of discussions on forks recently but no one has mentioned which way up the seals go!

I've recieved some new sidecar fork springs this morning from Draganfly... (Yes I'm still on the idea of fitting a sidecar!) and now in the process of fitting them. Not so long ago I replaced the steering head bearings and stauncheons along with new oil seals, all purchased from a good known dealer. I remember asking on another forum which way up should the seals go, half the guys said this way and half said the other, so I fitted them according to what I thought was correct. Damn things have leaked since!

SO! Looking at the photo... *IS* this the correct way up or not? I need to get it right as it was a horrible mess, blummin oil everywhere.

[bsa-bill]

look at the seal, it works by useing the pressure of the oil behind it to force a lip onto the shaft/stantion whatever to seal

All the best - Bill

[snowbeard]

I actually don't know today, but should by tomorrow (getting a set of seals from a friend)  but I might suggest whatever way you did it before, don't do it that way again!?!  

[dpaddock]

You don?t state specifically from where the oil is leaking, LJ, nor the year and model.

BSA Service Sheet No. 706 says to insert the seal into the seal holder, metal part first, and then drive it home with a mandrel (tool number 61-3007). Viewing your photo, it looks like the seal is oriented correctly.

Do the new seals have the same dimensions as the originals (assuming they worked properly)? Did the rubber edge get damaged? Did you wrap one turn of twine around the thread before screwing the holder onto the fork leg? (A better, more modern sealing method is to use Teflon tape or Loctite sealant [not thread-locker]). What quantity and grade of oil did you use?

David

[Lannis]

LJ -

Easy rule.  Seals on our BSA forks and shafts generally have a metal spring providing pressure on the seal lip.

This spring ALWAYS goes toward the oil you're trying to keep inside, not toward the outside world.

Another thing I've found very successful - use ATF in your telescopic forks.  It's effectively about 20W, the right viscosity, and it is DESIGNED for environments with sliding rubber and metal bits and being squirted through orifices, and being able to get on friction surfaces without ruining them (all part of life in an automatic transmission). 

This makes it Perfect for telescopic forks, as well as primary cases with wet clutches (where the primary does not share oil with the engine, ie BSA twins are OK, triples and unit singles are not).

Lannis

[A10Boy]

Agree with all the above, drive the seal into the holder - seal spring towards the oil as usual - seal the threads with loctite, or PTFE tape which you can buy from B&Q, remembering to wind it in the direction of the thread - 3-4 winds will do. ATF is great too.

[Richard]

it looks as if i was wrong with my advice on the seals LJ I have also checked with a google search and it seems that the other chaps are correct i.e. flat side away from the oil.
However I also asked about using ATF in the forks a little while back and even though the viscosity was about correct I was advised not to use ATF as it did something to the seals or caused some other corrosive problem within the forks but I do not remember what.
On another note I have the swan neck diensions now and will look tomorrow as it is 11pm now
Richard

[A10Boy]

Its interesting you say that, as my Z1's factory spec is for ATF in the forks and that has all the usual components / materials found in BSA forks.

[Lannis]

it looks as if i was wrong with my advice on the seals LJ I have also checked with a google search and it seems that the other chaps are correct i.e. flat side away from the oil.
However I also asked about using ATF in the forks a little while back and even though the viscosity was about correct I was advised not to use ATF as it did something to the seals or caused some other corrosive problem within the forks but I do not remember what.
On another note I have the swan neck diensions now and will look tomorrow as it is 11pm now
Richard

I've used ATF in forks and primaries for years on several different models of bikes, and had nothing but benefit from it, no sludge or corrosion, long life, no clutch slippage or sticking, better fork action.

Perhaps you're thinking about modern hypoid 75W-140 gear oil attacking bronze bushings in our old transmissions, a good reason to stay with old 90W?  That seems to be a real problem.  But that's not related to ATF. 

If there IS any hard data against ATF I'd like to see it and be able to evaluate it vs. my experience.

Lannis

[Richard]

Sorry chaps but I have no hard evidence   BUT I think the person that told me not to use ATF in forks may be at Wicksteed so I may ,if I remeber, ask him why
Richard

[Brian]

I've been watching this thread and others over the last couple of years about using ATF in forks and I am intrigued. I always thought ATF was for automatic transmissions and fork oil is for forks. Am I missing something here, fork oil is cheaper than ATF and is designed to go in forks, its available at any bike shop in any weight you want, why use ATF ???

Just for the record I use multigrade engine oil in my forks and primary drives, always have and probably always will. If you have had problems with clutch slip or drag and thought the oil was too heavy then your wrong, its because your friction plates are crap, throw them away and get some good quality ones. I only use Surflex plates althought I have a set of Barnett's in my 61' A10.

Now I am probably going to get a bit of flak over the comments on ATF because I know a lot of people use ATF but I just cant see why, every type of oil has its specific use. Why not use the oil that is designed for a specific use for that use. Fair enough if there is not something available to do the job but when there is, use them.

There, take that........................................

[BSA_54A10]

OK Brian,
I will stand shoulder to shoulder with you on this one.
Fork oils for forks, ATF in the transmission ( read primary) .

[LJ.]

 My Update...

Well the job is done and the results are... Interesting! I wasn't looking forward to the test ride out as I thought it would all have to be stripped down and done again. 

I was expecting a much more bumpy ride as I had fitted sidecar springs and indeed it was so, but I can live with that as this bike, the red A10, is my touring bike and is often loaded up with camping gear and such like. No oil gushing out yet! keeping fingers crossed although the chrome oil seal holders might take a while to fill up before overflowing! 

But I must admit there was quite a noticeable difference in the handling of bike and... a big improvement on the front brake something that really suprised me as I had not adjusted the twin leading shoes at all, just cleaned out the dust and put it all back together again. There had been a judder on braking before but this was no longer noticeable?? I wonder if a very slight judder is felt through softer solo springs?? 

All that remains now is to twist the front forks around to get the handle bars horizontal to the wheel as they are cockeyed at present, should not pose too difficult a job.

Thanks for your replies!

[Lannis]

OK Brian,
I will stand shoulder to shoulder with you on this one.
Fork oils for forks, ATF in the transmission ( read primary) .

Hey, you guys are not going to hurt my feelings with that sentiment ... I could argue that side too!  It makes sense.

My usage is based on trial and error and experience.  I understand and appreciate the theory, but as the military guys say, The Book gets written by guys who didn't follow The Book.

I like to change as things need changing.  For example, on setting the timing for an older bike, I will get it "close" using the book values, then adjust it so that the bike is not "pinging", not overheating, making good power, and set it there, regardless of what the spec says.

I know other guys who religiously set the timing according to the manual.  Despite possibly having some carbon in the chamber, despite vastly different fuels and octane ratings than 50 years ago, despite all the other variables of load, altitude etc. - they'll set it by The Book with a micrometer and be happy.  Never mind that the bike is pinging and overheating and not making much power, it's at 5/32" BTDC plus or minus a mil and that's what it's supposed to be ....

At any rate, timing, oil, or tires, none of it is the Pelagian Heresy, is it?   

Lannis

[Brian]

Totally agree Lannis. Whatever works best for you is the way to go. Thats why I use engine oil in my forks and primary, I reckon its better.

Just quickly on the timing thing, I run 5/16" or round abouts. I set mine with the fag paper method so its never going to be accurate to the degree but I have always done it that way and it works well for me.

The main thing is to get them going and ride them......................................................