The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: georgesgiralt on October 05, 2013, 02:18:53 PM
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Hi Lads,
I had a plan and an agenda today.
This morning the day started with the washing of the R65 to clean all this oil the engine has got from various leaks.
Then I planned to change the fork seal on the right leg which was leaking, then progressing from front to rear, fix the steering bearing pre-load, then the leak at the distribution cover, then the push rods, left side first then right.
Things stopped at the fork.
I put the bike back on the road in 2012 , early April. So at that time I dismantled the forks, removed the goo the rubber stop had left inside then put new seals, rubber stop, SAE5 oil and go riding. 6 month later I changed the fork oil discovering that the stop rubber has disintegrated in very small cubic parts and very brittle. So opened the fork to change the failed white rubber stop for the orange the BMW dealer provided. I did not touch the seals at that time. I surely did something wrong on the right hand tube because it started leaking a very little then and, of course, more and more. So today was it's day.
When I opened the drain plug, with the oil came small red coloured rubber parts... I dismantled the fork just to find that the rubber stop has failed in very small bits, this time still supple but failed anyway. As I did not ride more than 5000 km since the previous dismantling, I wonder if the fork oil (Bel Ray SAE 5) is the culprit or if I missed a point here ?
This bike is becoming like a chopper : 1 hour flight, ten hour shop maintenance...
What do you think ?
Is there something I should know or am I supposed to go to the Marabout to have a disenchanting prayer done ? :D
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Usually that rubber washer isn't getting 'used' until the fork extends all the way, not overly common in my riding .
I vaguely remember you saying in a posting awile ago about the fork springs and I think spacers that were on top of the fork springs to tighten up the forks due to the full fairing you had on the bike .
I wonder if the springs may be the cause of your fork issues .
I don't think that Bel Ray oil is in any way causing the washers to come apart .
Do the fork tubes have any pits or high spots from being hit by road debris and causing 'burrs' on the fork tube that may be cutting or damaging the fork seals ?
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Georges,
The topping out bush should be sandwiched between the underside of the damper piston and the perforated valve plate. Is that the location you have installed the bush ? Tell me you didn't install it between the spring and the piston. That's the only place I can imagine it getting chewed up in such a short time.
If it's in the correct location the bush effectively gets struck by the piston when the forks top out but there should be nothing sharp that would cause damage.
If the forks were topping out viloently I'd expect you would hear a severe clunk. Were there any noises ?
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Hi guys,
Unless I'm deaf, no big noises. As the rubber is totally destroyed, no means to know if I put it in the wrong place last time I changed it.
I was, too, not convinced the oil has destroyed the rubber in such short time. And I am pretty certain that the Bel Ray oil was not used before. So the previous rubber was destroyed by another oil... What are the odds ? Two bad and dangerous oil out there ? :-? I don't think so.
Last time I dismantled the fork, I measured the springs and I was glad to find they're still are the nominal length. Of course I removed the spacer when the fairing was removed.
The more I think about it, the more I think either I've assembled the whole thing wrongly, or that something is cutting the rubber stop. So tomorrow, I'll check for burrs, metal proud on tubes and things like that.
I wonder if I have the correct set of parts on the fork. So I'll buy from #19 to #24 on the fiche and replace my 30+ years old parts with brand new one.
This time triple checking on the factory manual the correct stacking and procedure. And I'll see...
Still these damn leaks to address.... And not so much time ! Grrrr.
Thanks for your advice !
P.S. Do you know how one remove the ring holder ? There is goo and small debris I can't reach at it's base and I'm unable to unscrew it.
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what year is the bike?
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I know the last time I rebuilt my forks the BMW mechanic is go to for advice and parts ( I trust his advice ) told me to use 15w fork oil. He was trained at the factory and has raced BMW's for 30 years. I did use 15w, the ride is a little stiff (I don't mind it) and haven't had any fork issues since.
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I've only about 600 miles on my forks since the rebuild in June (two other bikes have limited its outings), but no worries so far - reference to my thread in the FAQ section, if you have a 1981 or later bike. Did you place the red/orange bushines in the position as shown in those pictures? I cannot imagine those disintegrating so quickly.. I would definitely consider using either BMW branded or perhaps Honda branded fork oil - I have had good experiences with both, and at least that might be a factor to consider for this premature failure.
http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1371526053
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That's why I asked the year of the bike. I'm pretty sure the internals changed and the pictures of my '79 fork would not do him any good.
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She was made in April 1982.
Nhmaf, the fork looks like yours except for the bottom part which is the old design (only one part and no spring).
As you've done, I'll change the exact same parts.
I hope I'll find something different on the other leg, and maybe explain why the right leg act funny.
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The topping out bush is not shown in nhmaf's pictures. The white plastic thing to the right of the perforated valve plate is the valve washer. The topping out bush should be to the left of the valve plate as shown below.
Georges,
I'm thinking your damper components look like the picture and the diagram. The topping out bush is #24
Think about why we have the topping out bush at all. It's there to cushion the blow when the forks top out. Without it there would be metal to metal contact and the shock loading would eventually shear something off.
Just about every other motorcycle fork including the otherwise identical R80st has a topping out spring in place of the bush which serves the same purpose.
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I think 5W oil is too light for a road bike and would lead to bottoming out more frequently especially with fairing,15W is better,start with normal quantity and you can adjust ride feel as needed by adding or taking out a little as needed,use a hypo syringe with clear plastic tubing,fill forks to spec level and mark the clear tube then to remove some put a higher mark on the tube simply lower into each leg and suck up ,no need to do anything else but to keep a record ,cheers Nev
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So, this morning, I cleaned everything and prepared the order to the dealer.
The more I think about it, the more I think I was wrong when reassembling the whole fork. I've found in the garbage one old #24 rubber ring. It has circular marks from the perforated washer on one side and concentric marks on the other side (maybe from the top of the damper rod). Alas I can't reuse it, it is split in two parts... So next week will be on the Honda. :(
But, I still wonder, if the assembly was wrong, how did I reassemble the whole lot and still had it looking good ?
If I understand it correctly, the first piece to put on the rod is the rubber red washer, then the perforated washer, then the white plastic washer then the big support part and, last, the conical part used to centre the rod on the tube. So the above picture miss something ?
Nhmaf, where did you get the P/N for the rings ? RealOem shows them for the big displacement engines. Did they fit the R65 fork ?
As per the oil, my bike does not have the fairing any more. I removed it in 2012 (it was in not so good shape and I thought that at around 170 000 km I could ease her old days by removing it). I tried 10W oil and it was a little too thick (for the bad roads I have around my house) and did not ease the back pain I suffer ... The local Guru said to use 5W (and sold me the BelRay, BTW) and I was satisfied by this thickness. Maybe I could try 7.5W if I can find some.
I measured the free length of the spring. It is at 500 ~ 502 mm depending how I measure it. So good to go.
Thanks for your help.
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If I understand it correctly, the first piece to put on the rod is the rubber red washer, then the perforated washer, then the white plastic washer then the big support part and, last, the conical part used to centre the rod on the tube.So the above picture miss something ?
If the damper rod and piston are already pushed up inside the stanchion bore. The assembly sequence is #24 topping out bush, 23 valve plate, #22 valve washer, #21 damper valve body, #20 shim (optional and available in various thickness), #19 circlip that secures the damper valve assembly in the bottom of the stanchion.
#18 is the full compression hydraulic bump stop and it just drops in the bottom of the fork leg.
Oil viscosities are all over the place and quoting viscosity at 100 Deg C is meaningless. To make a choice you really have to look at the viscosity at 40 Deg C. I use 5W Castrol synthetic and consider it OK but marginally too thick (28CSt at 40 Deg C) Other 5W's like Motul (18 CSt) I found too thin. When you find something you like use it's viscosity at 40 C to find something comparable of a different make.
15W oil tends to be in the high 40's or 50 CSt and I imagine would make the ride very firm. Definitely not for me and not what BMW intended.
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Barry - if you look at the pics I put on PAGE 2 of my earlier thread - you will see the damper assembly put together with new parts in the proper order. George- the later pics include pictures of the BMW parts in their factory packaging, and shows the part numbers, including those of the piston wiper rings. I got the rings from going to the local dealer, who has a man in their parts department who is VERY knowledgable in airhead parts. He triple checked that these were the proper parts, and I think that he was correct.
My suggestion for using BMW or honda fork oil isn't so much a matter of viscosity, but chemical nature-thinking perhaps there is something about the Belray oil you tried which is not compatible with the red plastic bumpers. It isn't likely the case, but do you want to be doing the job all over a third time - unless you determine that there was an assembly error that caused it.
At least with the old style one piece damper valve, you are not trying to apply 75 pounds of force to compress that spring so that you can install the bottom circlip!
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Barry - if you look at the pics I put on PAGE 2 of my earlier thread - you will see the damper assembly put together with new parts in the proper order.
OK I see it now.
Georges set up will be the same except he has the earlier single part valve body.
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Thanks Lads !
I hope I'll be able to order the missing parts tomorrow (maybe the dealer is opened, who knows) otherwise I'll have to wait until Tuesday to order them and if lucky, to the week-end to put a hand on them.
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I hope it is no longer the case but 30 years ago Belray fork oil proclaimed itself to contain "seal swell" additives - namely brake fluid, the mortal enemy of a lot of rubber like products.
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I would avoid the Bel Ray oil for re-assembly but I'm pretty sure that the previous failure occurred with another brand and viscosity.
In fact, every time I go to a bike parts store to buy fork oil, I find a different brand !
As I need low viscosity for the BMW, I'm often obliged to go to a couple of shops before getting the proper oil.
I've ordered the parts at the Classic BMW shop; I do hope I've won a couple of days for the delivery.
And the rings are not offered for the R65. You've to select an R100 as the vehicle to be able to get them ;-) Cheap though.
My wife told me the r65 looks nice without the front ???? I do not know what to think about that ? :-/
I'll keep you posted.
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Hello !
Today, having a couple of hours to spare, I cleaned all dismantled parts, and get ready for reassembly when the parts show.
So I got a question : The Circlips is not a plain one. It has teeth protruding on one side. So I was wondering if they are meant to press on the valve bush like a spring or if they should face outwards ?
What do you think ?
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So I was wondering if they are meant to press on the valve bush like a spring
That's correct Georges.
The earlier full length valve bodies were shimmed to remove all free play. Mine is of that type.
The later shorter valves bodies like nhmaf's used a strong spring to remove all free play although the spring also has another purpose to absorb shock loading.
Yours is an intermediate type that retained the full length valve body and used a seeger circlip with spring tabs that eliminated the need for shimming by combining the spring with the circlip. It was done to speed up production in the factory as there was then no measurement and shim selection required. So yes the spring tabs should face upwards towards the valve body.
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Hi,
Today I opened the second leg.
Same status. The rubber stop is some goo at the bottom of the fork.
Yesterday, I've bought a litre of Motorex Racing fork oil, 7.5W weight.
The parts have left the BMW shop in Germany. Go DHL, go !
Maybe Sunday will be good for the bike.
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Hello Lads,
Waiting for my parts to show, and as a way to kill the time, I read every manual I own about the reassembly of the fork. the French "Revue Technique" is by far the worst and less detailed. so skip it. But on the Clymer manual, they state one should align all 3 ring gaps together before putting the piston back in the tube. I thought I should spread them evenly to increase the seal ? Aligning the gaps will make a leak ? So I surely miss something here ?
What do you think ?
Oh, I forgot, I assembled on leg to see the end play the valve seat has on the tube. Event with the Circlips, there is a little play, I must admit that the rubber ring is missing but, I wonder if I will need a shim or not ? This time I will check everything hoping not to reopen the fork in the next 30 years... 8-)
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I alway spread the ring gaps 120 deg apart but who knows where they end up over time.
It's the valve body in the stanchion recess that may need to be shimmed and the rubber ring makes no difference at all to that as it sits above the recess. It should only be on the very earliest forks like mine that shims are needed. Are you saying even with the sprung seeger circlip there is still some play in the valve body ? The whole point of the sprung circlip was to eliminate the need for shims. If there is still some play though I would add shims above the circlip.
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I have read of several versions as well, and after trying a couple ways, here is what I did -
One has to compress the rings again so that the fit inside the smaller part of the fork tube bore. One suggested approach is to use a few (sacrificial, because there is likelihood they will get severely kinked) thin feeler gauges (approx .004 - .006 inch) to squeeze the rings inward. However, to insert the damper rod with rings back up from the bottom means that the "step" that is machined on the inner diameter of the fork tube is approximately 2 inches or more up inside the tube, and it this step that is what the rings will catch on and damaged them. To try to get them to compress in that space where you cannot see what is happening with extra long feeler gauges did not seem very likely to work well, and so I decided to tackle the problem from the other (top) end.
Put the piston rings onto the damper rod unit, and also place on your new, red rubber top bushing, but leave the other parts, including drilled circular plate, white plastic washer, etc off. Take your sacrificial feeler gauges and put them on either side of the top of the fork tube and insert them far enough so that they will keep the piston rings compressed until after the rings have gone past the groove for the top round circlip (only about 1 inch or so). Insert the damping rod unit with the red rubber piece in place down into the tube. I did align the rings gaps on the piston rings so that I could easily squeeze them to compress with my fingers and get them inbetween the feeler gauges, and slowly push the damper rod assembly down into the tube from the top. Once it has gone in a little way and the rings are past the top inside circlip groove, you are good!
Then use your socket wrench with extension to push the assembly further down into the fork tube until the bottom threaded end of the damper rod is not quite out - do not push too far because if you push the piston rings past that inside "step", you'll have to carefully draw it the rest of the way out and start all over again!
While the end of the damper rod is still inside the fork tube, I grasp the end of it and give it a few quick rotations of various degrees in both clockwise and counterclockwise directions. I found that this was usually enough to get the ring gaps to move around so that they weren't all lined up together - they weren't perfectly redistributed, but I figure they will do some moving anyway..
So, now you can put the other pieces onto the bottom end of the damper rod from the bottom of the fork tube in their proper order, fitting the retaining circlip on the bottom, and insert the base piece before inserting back into the sliders.
This seemed to work for me and I avoided the challenge of making a ring compressor from a beer can that would do the job inside of the bottom of the fork tube without cutting my fingers.
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I feed the damper rod and piston in from the top too. That tapered section under the groove seems made for the job.
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Yes, there is some play (very little) even with the Circlips installed the correct way. Maybe it has eroded a bit in the last 30 years ... I have ordered a lot of shims with the red gum .... On the other hand it is difficult to measure. I'll try when the fork will be reassembled and the spring is pressing. Will see if there is some play.
I've destroyed a couple of feeler gauges putting back the damper piston back in place and made a guide using a beer can (if you turn the part on the outside, like a shirt collar, this part stop on the tube and you do not have to hold this thin cutting steel with your hands during the reassembly).
My mechanic has a nice set of tools to reassemble the forks without marring anything. I was astonished by the tool. So he told me the price. I stick to the beer can and heal myself drinking the beer ...
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Georges,
The main spring being installed or not has nothing to do with play in the valve body except perhaps when the the forks are at full extension so that's not the time to check it. There should be no play before installing the main spring. Without a shim I had 20 thou play which allowed the valve body to audibly rattle up and down.
If you have bought shims from BMW there shouldn't be an issue but just to make you aware of a possible problem. When the forks reach full compression the tapered top hat hydraulic bump stop #18 actually enters the bottom of the damper valve body. It functions as a bump stop when due to the taper the clearance between it and valve body reduces and there is no where for the oil to go. My point is before assembling the fork make sure that it fits inside the valve body without fouling the shim. You can guess why I mention this having made my own shims. For information #18 is not the same part for the 3 different generations of valve body and this clearance issue is the reason why.
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Hi !
Thanks for all the advices given. they're invaluable.
This morning I got the parcel from the BMW classic shop (ordered Sunday afternoon, shipped Wednesday, received Friday ! Free shipment for orders above 75€ which is not so bad).
The rings are the good ones. See the picture : On top left, the two new from set one, on the right the second set pouch and on the lower line, on the left the old 30 years old and on the right the new ones. The old set has a square section, the part in contact with the fork tube being shiny. The new rings are oval in shape (a stretched oval, that is) and the whole thing is mat black. Looks like it has had a treatment of some sort.
I got the shims from BMW and I'll look twice at the assembly before returning the fork leg into use.
I still am confused about the rings. Should I set them with the 3 gaps aligned or separated at 120 ° angle ? Can't decide from postings above.
Oh, and BTW, BMW selected to send me 6 sets of rings... at 5.76 € each and I asked for a return of 4 sets, as I've no use of them. So new shims for the two legs are at 5.76x2 € ! not so expensive. And they are made in Germany...
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I set them 120 Deg apart and drop the damper rod in from the top. I'm sure they must then move randomly but the gaps never seem to be lined up when I take the damper rod out the next time.
As for why the new rings are oval in section and not rectangular I wonder if it is to reduce friction which has been a problem. Either that or it is cheaper to make them in the new shape.
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Hop, The two legs are assembled again.
New rings, new rubber damper, new felt, new sealing washers, new lip seals and of course new oil.
I'll had to put shims between the valve seat and the circlips. 0.3 mm on one side and 0.5 mm the other side. Maybe should I had ordered new circlips.
I'll go begin to address the leak at the timing chain cover, then I'll put the legs back and torque the steering properly.
I'll then be left with the left cylinder leak.
busy week end.
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The piston rings are an oddity - it requires (3) per leg, and according the the BMW dealer inventory system, they charge you by the ring. Yet, they are indeed packaged 3 rings per packet. So, when they sent you 6 packets, they never bothered to look at the contents. I've wondered if the pricing is actually supposed to be per packet, instead of per ring, because of how they are packaged - and how expensive it gets to buy 6 rings.
My original rings are still oval in cross section - the new ones are actually a little bit more square-looking in cross section for some reason - the opposite of what Georges observed. Hmmm.
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Hi !
So I rode the bike for around 50 km. Mostly highway and city.
The feeling is very different. looks stiff but I would say it is not. It's strange.
The riding on the highway is very smooth. The bumps in the city are smoother than they where. But as the oil evolved from 5W to 7.5 W maybe that's the reason why.
The steering is also stiffer. No instability any more. Maybe a bit too stiff.
I have to check if the travel is as free as it should be. Maybe the pre load is too much.
Maybe I assembled the whole fork wrongly ?
I don't know, I'm a bit puzzled.
How would you assemble the steering and forks legs on the bike ? How could I tell if something is wrong ?
Something positive is that the oil leaks on the timing cover and on the left barrel are gone. Thanks god.
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When the steering is too stiff your handlebar inputs tend to overcorrect when overcoming the steering resistance. This results in a weave at low speed. If you don't have this weave I wouldn't worry.
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So, after sending back the extra rings to the BMW Classic shop, they sent my money back.
23.04 € for the 4 sets. So it is 5.76 a leg. And it is for the set !
You should ask for a refund if you were charged more.
As I'm very far from home, the bike sits in the garage, having just the Optimate to speak to. I miss her !