The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: georgesgiralt on January 22, 2025, 05:51:46 AM
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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.
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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.
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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 .
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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 !)
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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.
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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.
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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.
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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...
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A 50/50 mix of 5W and 10W will give you 7.5W.
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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 ?
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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.
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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. :clap:
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Pics please!
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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 : (https://i.servimg.com/u/f19/17/79/70/72/img_2101.jpg)
And I now see again what was buried under a lot of brake pad deposit sealed with oil and road grime...
(https://i.servimg.com/u/f19/17/79/70/72/img_2102.jpg)
I'll have a new front fork soon !!
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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...
(https://i19.servimg.com/u/f19/17/79/70/72/img_2106.jpg)
Discoloration of the old tube
(https://i19.servimg.com/u/f19/17/79/70/72/img_2105.jpg)
Hope to finish the bike tomorrow...
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George,
What was the turn around time from the date you ordered the forks, please? I understand that things in Europe are a little quicker.
The exchange rate for me in Australia is favourable but the postage will be some thing extra and I have the option of having them shipped to the UK and carried out for me.
Cheers, Burt.
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Hello Burt,
I ordered them on Feb. 12th (and paid them by instant European wire transfer, something which could normally take time) and the parcel was scheduled for delivery on the 18th. Which I had to postpone to the 19th because I was not home on the 18....
The seller, Moto-point.pl said he is speaking English, but you'd better ask Deepl.com to translate into Polish ;-) I can't tell for the maker, Acribyus because I did not contact them (and I doubt they will sell to individuals ? ).
These tubes are sold in France by a reputable pattern part seller (Bihr). I bet they are from the Polish maker. And the price is greater than the Polish one but far less than the BMW tag. So maybe some pattern part maker will/could sell them Down Under .... And the price may be reasonable if you think of the shipping costs...
I've to get the reassembly going ! Have a nice day !
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Thanks George,
A quick turnaround was what I was after, instead of weeks. That is good to know and most helpful.
I shall contact them and explain my options, in Polish as well. They are for a K series BMW and I can borrow another set of forks as an interim measure. I have someone travelling from the UK to here in two weeks with a few parts already, so that is one of my options.
The price of two of them is still less than the price of one here. :wall:
Cheers, Burt.
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So perfection is not of this world...
I can't install the stanchions on the bike.
The hole on the yoke is a bit too small (around 6/100 of a millimeter) because the new stanchions are a bit nearer of the nominal 36 mm diameter than the BMW supplied ones.
I've to remove this material on the aluminum yoke hole because I will not be able to remove that amount on the stanchions (hard chrome, and the thickness of the chrome deposit may well be less thick than that... ).
So I'm looking for a smooth way to do this on my garage... And keep things straight and perpendicular in order for the fork to have no stiction...
Any ideas ? Tricks ?
Thank you for your help !
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I can think of ways of removing material with a suitably sized flap wheel but the problem is keeping the holes parallel and truly perpendicular to the yoke. Only machining can do that.
Another thought, if the old stanchions are scrap how about applying grinding paste to them and using them as a lap by rotating inside both yokes at the same time to maintain alignment. 0.06mm is quite a lot to remove that way so it will be a slow job.
Whenever I remove my stanchions and replace them they are a tight fit and I need to insert a hardwood wedge in the gap of the yoke to gently open them up a little.
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Barry, good thinking. I'll give it a try if I've to machine them. Someone in France, suggested to heat the yokes at 80°C and that should do it. So i'll try this first...
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I've used heat from a heat gun to remove and replace stanchions
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I was discussing this over the weekend on a motorcycle trip and the suggestion was to use 80 grit sandpaper on the stanchion. It will dull the chrome finish but may solve the problem. Kerosene was recommended as the lubricant as it can be a bit abrasive as well but I have not heard of that before. The usual criss-cross pattern to even it out and don't use Carborundum sandpaper. A lot of work though and I just don't like the idea of removing material from the yoke. Unless it is the last resort and done in an engineering workshop.
If you are planning on using heat then you may want to find a large enough freezer to throw the stanchions in for a while. Alternatively, is there any snow outside? For my way of thinking, I would only be using heat if something is designed as an interference fit and it is recommended as an installation procedure.
As I am still considering a set of those stanchions, I have the option of access to a lathe. However you mention you are carrying out the work in a garage, so not an option for you as that would be my preferred method in this situation.
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Some progress and success.
My set up :
(https://i19.servimg.com/u/f19/17/79/70/72/img_2108.jpg)
I used the old tube to make the fork geometrically correct and the whole is tightened properly with the correct torque.
and after heating up to 70°C ~ 80°C here I am :
(https://i19.servimg.com/u/f19/17/79/70/72/img_2107.jpg)
There is even some play (I can't measure it)
And the yoke is not forced open by any mechanical method. Only some heat...
So I bet I won't need to grind the yokes, after all...
Some more pictures when the bike is reassembled...
Thank you all for your insight and help !
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Starting to look the part ....
(https://i.servimg.com/u/f19/17/79/70/72/img_2109.jpg)
I heated to 50°C ~60°C and it was enough to slide the tubes.
The difficulty was to set the proper 190 mm measurement and clamp the tubes in the same time. The tubes slide very very well when the yoke is heated...
Today challenge is to put the fork on and install the upper yoke. ....
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An update.....
Searching to prove me right into the BMW Maintenance manual, I stumped on the dimensions and tolerance for the fork tubes and stanchions.
The new Polish ones are only 1/100 mm above tolerance and the old ones are between 2 to 4/100 mm under tolerance.
I bet that this smaller tube make the wiper's gasket job very difficult...
As the fork is assembled and on the bike, I can't measure the inner diameter of the fork tubes but ....
It is funny to note that the hard chromed stanchions which are very very hard are the parts wearing the most !
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An update on the depth measurement...
I've just dropped a thin steel rod down through the spring and I get 470mm to the top of the stanchion plug.
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Thank you Barry, I've got the same measurement. Do you get the rod wet ? And if yes, how many mm got wet ?
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Yes rod was wet.
I aim for 35mm which is the the middle of the recommend range of 20mm - 50mm above the damper piston top.
I have run as low as the 20mm level and the forks still work fine but with a softer feel and more dive.
My understanding is that 190cc should give a 35mm level. Where there is some confusion is that the BMW information says 190cc for both an oil change and a dry fill after the forks have been dismantled. That can't possibly be correct. I can recall members here recommending more oil for a dry fill perhaps 205cc but I'm not certain. It doesn't take much oil to increase the level. Many years ago I calculated the internal volume of the stanchion and subtracted the volume of the spring which gave a result of 3.6cc per 10mm increase in level. I predict that if you were to add only 15 cc more oil you will see an oil level on the dipstick.
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Thank you Barry for the follow up. I actually removed the oil on one side because I was thinking I may have omitted to put some in... So, now I've the remaining oil from the first fill an 190CC on top.
If I've some time tomorrow, I'll put my dipstick in and check...
Will report back.
Edit : So, I used my dipstick to check the side where I changed oil. You are right. 190 CC is good for a change of oil but not for a dry fill. On this side the level is at around 5cm on the dipstick. The other side is, as I told you dry... So I added some oil to get to approximately the same level (it is difficult to read the oil level as this oil is near transparent ).
I've learned a new trick.... Thank you.
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Ariette fork seals ,(Motobins).
I also spin the fork legs in a lathe and polish them, probably not the issue here, but good practice.
Beyond that I have nothing. I am smart enough to live where 18 degrees Celsius is a cold winter day.
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Hello Tony,
I spent a rainy afternoon measuring the worst tube. It is far beyond hope as the diameter varies where the seals have done their job during the years. Definitely very very worn . And a friend of mine which used to do a lot of hard chroming in it's days said to me that the cost of chroming them would be far above the price of the Polish new tubes....
I rode the bike in very cold weather and the seal did not leak so I consider the job done and the bike returned to serviceable status :bmw_smiley:
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The old stanchions look totally worn out. Notsurprised you had some issues. The new ones look, well, new!
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I installed gaiters on my `81 R65 in 2007 when I did a lot of work on the bike it had 80,000 miles, 130,000 km .
They didn't quite look right at the time, but seems 'normal' now .