Author Topic: Fork oil  (Read 5511 times)

Richard

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Fork oil
« on: 18.02. 2009 21:20 »
What is the view of the boaed relating to using ATF fluid in the forks on my A10
I was unable to get specific fork oil or SAE20 so was informed by a mate that he used ATF in his which also does not froth up.
Also to save me spending an hour trying to find my Haines manual how much ATF or oil do I put in each fork leg
Richard

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Re: Fork oil
« Reply #1 on: 19.02. 2009 09:36 »
You will find ATF way too thin in a pre unit twin fork.
The oil holes are drilled big for heavy weights of oil.
ATF is somewhere around 10 ( I think) so you will end up with "very active" forks.

In a pinch you can use engine oil.
On modern roads the problems associated with the oil foaming is not quite as bad as it was in the 50's when most roads were unsealed.

OTOH modern fork oil is 100% missable in itself so you can do a 50:50 mix of 40 & 20 to get 30 or 75:25 mix 40 & 20  to get 35.
I usually dilute some 40 with 5 till I am happy with the results as the exact amount of damping needed is both rider & machine dependent .
Just about every motorcycle shop stocks a large variety of fork oils and shops that specialize in off road bikes will carry a bigger range still.
Bike Beesa
Trevor   
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Trevor

Offline a10gf

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Re: Fork oil
« Reply #2 on: 19.02. 2009 10:00 »
Quote
you can do a 50:50 mix of 40 & 20 to get 30 or 75:25 mix 40 & 20  to get 35.
Never thought about that ! Thanks for the tip.

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Offline beezalex

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Re: Fork oil
« Reply #3 on: 19.02. 2009 18:20 »
FWIW, Richard, I seem to get the best damping action (still not great, but best I can get) using SAE 5-20 motor oil on my '53 A10.  Other motor oils were too thick, ATF too thin. 
Alex

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Richard

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Re: Fork oil
« Reply #4 on: 19.02. 2009 20:14 »
I believe 5-20 is a semi or full synthetic oil now I run my 61 S/R on semi so will that be ok for the plunger fork oil.?
bear in mind that the plunger will be my occasional go on a short ride bike whereas the S/R is my serious riding bike

I put this same topic on another forum and it is interesing to see the various replies and opinions

thank you all for the input
Richard

Offline beezalex

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Re: Fork oil
« Reply #5 on: 20.02. 2009 14:51 »
I don't know about synthetic.  I use cheap store-brand mineral-based oil.

Still, go ahead and try it.  I guess my point is, try a range of different oils and see what works.  That's how I ended up with my selection, but it may vary with bushing wear, aftermarket tubes with different drillings and/or clogged holes.  Aside from viscosity, any oil should work.  I think that due to the lack of any valving in these forks, the anti-frothing agents in fork oil aren't really going to matter much...
Alex

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Offline Goldy

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Re: Fork oil
« Reply #6 on: 20.02. 2009 16:53 »
I owned an A7 Shooting Star in the 60's and I used gear oil because the front was so soft.
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Re: Fork oil
« Reply #7 on: 20.02. 2009 21:11 »
It is actually worth the trouble of seeking out heavy fork oils and blending down till you find what suits you & your bike as against engine oils.
Fork oils are loaded with special addatives to preserve the softness of the oil seals , prevent corrosion and adsorb moisture none of which are found in engine oils.
If you use engine oil then it should be changed fairly regularly as the forks will end up with a lot of water in the bottom and then corrosion.
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Trevor

Offline Pim

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Re: Fork oil
« Reply #8 on: 17.03. 2009 16:18 »
Does this aply to a '55 a7 swinging arm to?
I was wondering what oil i should put in the forks.

I take it from here that it's mainly a change in comfort depending on the thickness of the oil? Or does it have to have a special oil for mechanical perfection?

Slow but steady...

Offline A10Boy

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Re: Fork oil
« Reply #9 on: 17.03. 2009 19:37 »
You should put 20 grade fork oil in there, nothing else - the forks were designed for it.

Its readily available at all bike shops, I always stock up on such "consumables" when in the BSA shop.
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Offline royboy

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Re: Fork oil
« Reply #10 on: 04.04. 2009 17:27 »
A10 Boy could you point me in the direction of the BSA Shop as I have been trying to get some SAE20 oil for my forks but no luck so far. I have tried Castrol Help Desk to see if they could recommend an equivilant but they don't do one.
Cheers royboy

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Re: Fork oil
« Reply #11 on: 05.04. 2009 00:56 »
Roy,
Are you really trying to tell us that no motorcycle shop in your area sells fork oil ?
There has to be a Harley shop on every second street corner now days and they sell a lot of heavier grades of fork oil.
There is absolutely zerro benefit of useing synthetic oil in your forks.
Standard mineral fork oil works perfectly well as long as it gets changed regularly.
The problem with our bikes is that we do not ride then for long enough, hard enough or regularly enough to get the fork oils up to fulll working temperatures so the water that condenses in there from the air never dissipates so it must be changed every 2 years regardless of weather it is $ 10.00 /L mineral oil or $ 35.00 / liter synthetic.

AS stated prevoiusly fork oils can be mixed proportionally to attain any weight that you like so go to the Harley shp and get some 10000 w tractor oil then down to the rice burner trail shop and get some 0.0001 W saki juice and blend away.
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Trevor

Offline Mosin

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Re: Fork oil
« Reply #12 on: 23.06. 2009 12:24 »
This might seem like a slightly silly question, but I am about to trplace my Fork Oil and I see from the manual that the recommended capacity is 213cc. However, my manual does not say if this is the total amount of fork oil or if there needs to be 213cc in each side. Can anyone confirm?

My bike is a 1960 A7 ss

Thanks,

Simon
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1959 D3 Bantam
1994 Triumph Trident 900

North West England

Offline dodmo

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Re: Fork oil
« Reply #13 on: 23.06. 2009 16:21 »
According to this (which is for the older models) it is 213ml per leg. So I should imagine it applies to your '60 A7.

Online RichardL

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Re: Fork oil
« Reply #14 on: 23.06. 2009 20:43 »
Dodmo,

Thanks for the BSA Wiki A&/A10 site reference. I think this answers Mosin's question perfectly. I can't figure how I missed stumbling over this site, considering how much I've researched online. In addition to the fork info, there is a wealth of other official service info, as well. Now I feel like taking a dipstick to my forks, just to see how it looks after about 1000 miles since rebuild.

Richard L.
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