R65 1982. Fork seals failling when riding on cold outside temperature .

[georgesgiralt]

Hi Guys,
I need help and wisdom.
My old and trusty R65 has fork seals leaking. This happens when I ride outside temperature is around 0°C.
This time it is the right stanchion, but last year it was the left. Every year there is one or the two failing.
They are OEM BMW supplied, green/blue in colour.
I was told to shorten the spring by removing a couple of mm on their length but to no avail.
So I would like to get all the advice and wisdom I can get.
Thank you in advance !
Have a nice riding day.

[Barry]

Hi Guys,
I need help and wisdom.
My old and trusty R65 has fork seals leaking. This happens when I ride outside temperature is around 0°C.
This time it is the right stanchion, but last year it was the left. Every year there is one or the two failing.
They are OEM BMW supplied, green/blue in colour.
I was told to shorten the spring by removing a couple of mm on their length but to no avail.
So I would like to get all the advice and wisdom I can get.
Thank you in advance !
Have a nice riding day.

I've tried shortening the garter spring in the past and it did help but it didn't totally eliminate the leak. There's only so far you can go down that route without introducing added stiction.

[Bob_Roller]

I've got some general questions .
What weight oil are you using ?
What quantity of oil do you put in each fork ?
Any rough spots on the fork tubes ?
I've started putting gators on the forks when I replace seals .
They didn't look right when I put the first set on but I've accepted it since .

[georgesgiralt]

I've got some general questions .
What weight oil are you using ?
What quantity of oil do you put in each fork ?
Any rough spots on the fork tubes ?
I've started putting gators on the forks when I replace seals .
They didn't look right when I put the first set on but I've accepted it since .

Weight oil : Don't remember the exact value but very light. I bet I've the bottle on the shelf, though
Quantity 190cc always put this exact same amount since 1984.
Rough spots : No I checked them more than once and they are more smooth than a baby's ass.
This is why I asked, as I can't find any reason for them to leak. (and as I do not use the bike that often, this increase the cost per km tremendously  !)

[georgesgiralt]

Can't find the old oil bottle. But it was Bel Ray low viscosity. Something like 2.5 or 5W.
It was something an old timer BMW mechanic suggested, I think.

[Bob_Roller]

I don't know if in real world application this makes any difference or not .
I used OEM fork oil 7.5 wt for decades.
It's now not available.
I started using Bel Ray 10wt for a few fork oil changes and had no issues.
The temps here in the Phoenix area usually don't get to the freezing area .
Low temps in the garage are around 60 F, 16 C when I leave for work around 4:45 am.
Air temps on the road upper 30's F to low 40's F, 4 to 6 C.

[Burt]

I was discussing this with a friend who does suspension stuff for a living.  The only thing apart from replacing the seals is, have you cleaned up the chromed stanchions sufficiently?  By this I mean rubbing or applying pressure equally with about 400 grade Aluminium Oxide sandpaper in a way that covers the wear areas adequately (criss-cross pattern) to remove any high spots from stone chips, insects, etc.  This is what we used to do on small aircraft when replacing leaking undercarriage struts.  Obviously a lathe would make this easier.  The only other thing could be a low spot spot on the stanchion. 

Generally speaking, I believe the BMW OEM seals are the best.  Is there any chance that the seals have gone hard, as in old stock way past its use by date?  I'm thinking of the very small amount of thermal expansion/retraction that occurs between dissimilar materials during extreme temperature variations combined with wear. 

Is it possible the stanchion is sticking and the leak occurs when you start riding and is still visible at the end of the ride? 

I'm not criticising anything you have done but just trying to suggest possible causes. 

[georgesgiralt]

Bob,
I spent some time examining the fork stanchions (and I *also* used a magnifying glass).
They are fine and "pristine" (given the age they have ...).
The only defect I can see is a slight discoloration (the chrome colour going to a shade of gold ).
No bump or crevasse I can sense or see.
I've also checked my notes. Last oil change was done using half 2.5 W and 5 W Bel Ray fork oil (someone suggested this could lead near 7.5 W grade... )
This oil change took place after replacing the left fork seal which failed ..... My notes do not specify replacing the right one, though.
So the plot thickens...
As I've no fork oil left, and no new fork seals, I'll ask the local BMW guru about the proper oil to use and ask for an expert exam of my stanchions...

[Burt]

A 50/50 mix of 5W and 10W will give you 7.5W. 

[georgesgiralt]

Hello,
I dig into my notes and saw that I was using Motorex 2.5W fork oil for ages.
Can't find the reasons and the rationale for switching to Bel-Ray and changing weight.
The nearest shop sells Motorex oil and has the whole range available (as he serves a lot of makes and a lot of enduro bikes).
So maybe I was told that 2.5 was too thin for the seals to function properly ?

[georgesgiralt]

Hello, it's me again.
I've consulted a lot about my issue.
A specialist about chroming told me that the discoloration I see on the stanchions comes from wear of the chromium deposit.
His opinion is that it's toast and should/must be redone (which is expensive and  difficult to find a shop able to do that in France where I live...) 
Then I showed the stanchions to a reputable mechanic I know and he told me I have a lot of residual pits from sanding the pits earlier and that will cause rapid wear on the seals. 
He then told me to install the stanchions on a lathe and remove the glazing the chrome has to ease the job of the seals using very very fine wet sandpaper...  Not good for the chrome left...
Then we checked one stanchion on the bench and found it was slightly bent (1/10 th of mm)....
So I asked my fellow French comrade for new/serviceable  bits (BMW ask 493 € apiece for a new one)...
They came back with this : https://www.moto-point.pl/produkt/bmw-r45-r65-78-85-rura-zawieszenie-laga/ which come at 100 € each.
So a set of two including postage is at 224€ ... Deepl did a very good job in translating our exchanges with the Polish guy, though...
I sharpened the knife and got to the pig to gather the money it held in it's belly...
I'll report back when I receive the stanchions ......
Stay tuned.

[georgesgiralt]

Update : The stanchions arrived today. Perfect and nicely done.
They are made in Poland by this company :  https://www.akrybius.com/
This week-end, I bet the R65 will get a testing ride. 

[dogshome]

Pics please!

[georgesgiralt]

Ha !
You know, retiree are sooo busy !
So for now, I've only got pictures of the tubes fresh from vapor blasting.
Boy, they are gorgeous !
I'll document my reassembly maybe this week-end and post picture then.
Look : 
And I now see again what was buried under a lot of brake pad deposit sealed with oil and road grime...

I'll have a new front fork soon !!

[georgesgiralt]

So you asked for it !
From top to bottom :
Old fork tube with discoloration marks (and other things less visible) https://i19.servimg.com/u/f19/17/79/70/72/img_2106.jpg
New fork tube with innards fitted ready to be installed
Box of the new tube from factory...

Discoloration of the old tube

Hope to finish the bike tomorrow...