The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: peteremc on May 01, 2016, 03:33:04 AM
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I'm posting here hoping for a quick response from someone who may know the answer to my questions. Initially posted over in Restoration logs, but looking for information quickly if possible.
I'm a novice at this but have disassembled by 1982 R65LS and got to the forks and was replacing fork seals and found that the "bumpers" that sit on the damper rod seats had completely disintegrated (see photo for how they came out of the forks).
Started to investigate, Monte helped out, but there is no indication of these parts appearing in 2 workshop manuals I have or in a number of on-line microfiche, and Chris Harris has a disassembly and reassembly of R65 forks on Youtube and these parts were not there on disassembly and were not installed in reassembly.
So, do I need purchase replacement parts or just reassemble without them?
If I need to reinstall, does anyone know what the part number is and are they freely available?
Many thanks
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There were no bumpers on the damper rod seats nor are they needed as the seat inherently acts as a hydraulic bump stop when the tapered section of the top hat enters the valve body. This is a standard feature of most damper rod forks.
Instead the red rubber bush sits under the damper rod piston to cushion the forks at full extension - item 24 on the diagram. Most every other forks uses a topping out spring in this position.
The rubber bushes are still available from BMW part No 2431421237215 or alternatively I used these from Motobins which fit even though they are not listed for our forks.
(https://www.motobins.co.uk/library/29020.jpg)
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Thanks Barry, but as a complete novice, I'm not understanding your advice.
You say there were no bumpers on the damper rod seats, so my first issue is that I don't understand what the disintegrated mess was on mine when I got them out.
Then you said the ring identified as item 24 on the parts diagram sits under the damper rod piston. When I look at the diagram, this is at the very top end of the internal fork mechanism to where I'm looking i.e. I'm at the very bottom where the damper rod seat is. I don't understand the relationship.
Maybe I'm missing something because I have not totally dismantled the forks. I've just removed the wire circlip from top of the forks and the screw at the bottom end of the damper rod so that I can separate the two parts.
Do I need to fully disassemble the forks or can I reassemble without bumpers on the damper rod seat?
Like I said ... complete novice here
Thanks
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Thanks Barry, but as a complete novice, I'm not understanding your advice.
You say there were no bumpers on the damper rod seats, so my first issue is that I don't understand what the disintegrated mess was on mine when I got them out.
Then you said the ring identified as item 24 on the parts diagram sits under the damper rod piston. When I look at the diagram, this is at the very top end of the internal fork mechanism to where I'm looking i.e. I'm at the very bottom where the damper rod seat is. I don't understand the relationship.
Maybe I'm missing something because I have not totally dismantled the forks. I've just removed the wire circlip from top of the forks and the screw at the bottom end of the damper rod so that I can separate the two parts.
Do I need to fully disassemble the forks or can I reassemble without bumpers on the damper rod seat?
Be assured that the correct place for the one and only red rubber bush is where the diagram shows it which is directly under the damper piston. Consider what happens when the forks reach full extension, without the bush to absorb the impact there would be metal to metal contact between the underside of the piston and the valve plate #23 which has been known to shear off the piston. As I said if you look at the internals of almost any other damper rod fork there is a short topping out spring where we have the bush. Why BMW chose to go their own way on R65 forks I don't know because even the R80ST forks which are otherwise almost identical to ours have a spring rather than a bush.
How yours got to the bottom ? Possibly a previous owner didn't understand the function of item 18 as the hydraulic bump stop and put it there in addition to one in it's proper place. The other possibility is when they truly disintegrate, the bits pass through the damper holes down to the bottom ending up as a sludgy mess. Other members here will confirm that.
You might yet find a bush or the remains of one where it's supposed to be so you do need to remove the large circlip #19 at the bottom of the stanchion which will allow the valve body assembly to drop out.
Let us know what you find, the valve body may be a little different to the diagram being a shorter 2 piece type with a spring but the topping bush should still be in the same place.
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Perhaps this will clarify:
Note the color of the sludge at the top. Kind of red-ish. And above the valve body.
Proper install sequence. The white nylon ring fits inside the piston.
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Let us know what you find, the valve body may be a little different to the diagram being a shorter 2 piece type with a spring but the topping bush should still be in the same place.
Notice Monte's 2nd picture illustrates the later 2 piece sprung valve body which is different from the parts fiche diagram. The spring will make removing and especially replacing the big circlip a little more difficult than it is with the one piece valve body and you will have to improvise something to compress the spring in order to do it.
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Read this thread-
http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1371526053/21#21
Chances are your 82LS may have the later spring valve assembly that my 82 LS has. It does make reassembly of everything a bigger challenge. I built a compressor with some 9/16" all thread, but the sheet metal I had was bent all out shape fighting the pressure of this short spring. I finally ended up using brute force, and having a helper - to slip the locking ring in place while a leaned on a socket driver to shove the spring back - it isn't a long spring, but that sucker is stout!
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I suspect the spring is stiffer than it needs to be. It is in fact the same part no as the topping out spring in the R80st so a parts bin expediency on BMW's part.
Peteremc, if you are put off at the thought of removing and replacing the valve body against this spring pressure the red rubber bush will come out of the top of the stanchion if the the damper rod is also removed from the top.
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Thanks all.
I'm firmly on what they call the steep learning curve. In a very practical sense. Hands on.
I went in and did the full dismantle of the forks and the photo below is what came out. It seems I have the earlier model forks without the hefty spring, which I hope will make reassembly a bit easier. Strange that some ‘82 LS bikes have different fork internals, as nhmaf obviously has different ones to this.
Another thing I noticed is that the fork springs are wound uniformly i.e. I thought they were wound tighter towards the bottom of the spring and had to be replaced the way they came out, but mine have a short, tightly wound section top and bottom. Wonder if they might be after market?
Now I see what's in these forks I get that the top bumper bush has probably just disintegrated and most of it ended up sitting at the bottom, because there were bits all through the forks, top to bottom. Big chunks and little chunks everywhere.
Fortunately, the rings (like piston rings) all look in new condition. I’ve seen what those babies can cost and I didn’t budget for that. Well, the budget is blown anyway, but that’s still a relief.
Thanks for the photos, parts diagrams and links everyone! I feel like I now know my forks very well and all this started with a simple replacement of fork seals. Also thanks for the tip on the bumper available from Motobins, Barry. I’m onto that one.
Thought I would include a photo of where I’m up to with reassembly at the end of today. Swing-arm in, nice and straight and torqued appropriately. Final drive mounted.
I would be a lot further except for the *&%$#*@!! centre stand springs. I have fought with these suckers for at least an hour to an hour and a half this afternoon. If not for this I may have the bike up on the centre stand, brakes in, and rear wheel mounted and could move on to other things. Very frustrating end to a productive weekend. If anybody has any strategy that I can use to get these damn springs in it would be appreciated. I will send beer!
Cheers
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What you have is a half way house between the earlier and later damper valves. You have the full length damper valve body with the sprung circlip to eliminate any end play. Make sure the little tabs point up wards when you re-assemble. This eliminates the need for shimming with item 20 on the fiche diagram so don't worry that you don't have that item. Curiously you have the later thick plastic valve washer which is a good thing.
The reason for several differences in the damper valve with respect to the fiche diagram and nhmaf's pics is because BMW improved it several times in an attempt to eliminate topping out clunks. There are at least 4 different arrangements in the first 3 or 4 years of production.
Just a comment on the Motobins bush. Unlike the originals they will last for ever but at the expense of providing less resilience than the original red ones. The red ones provide a softer cushion to the forks at full extension but don't last the distance.
The springs sound stock. They are dual rate with 66 coils of which 7 either end are closely wound. The springs starts off with 66 active coils to give a spring rate of 27 ftlbs then when the closely wound coils close up there are only 52 active coils which increases the spring rate to 34ftlbs. Wire diameter should be 3.5mm and is there an orange/brown paint mark on the springs ?
The trick with centre stand springs is to insert a washer or coin between each coil when they are extended. That will prevent the spring closing up and make it longer.
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The trick to put the centre stand springs is to have the bike actually sitting ON the centre stand.
THis is when the springs are the less extended. So easiest to fit.
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Now I feel like I really know my forks, thanks again all.
Those bloody springs! A couple of great tips there, so I'll get the springs and insert some coins (if my wife will actually trust me with money!) and put the bike up on the stand. I was only about 1/4" away every time I tried on the weekend so that should get me there.
Cheers
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Last time I changed center stand springs I used a bunch of "recycled" flat washers from a disassembly project a while ago - you don't even need to get in between every single coil - I found with the thick washer I just needed about 15 or so to give it enough slack to make it simple to pull the remaining bit to hook into place.
Those earlier style valves make it easy-peasy to re-assemble, in comparison - count yourself lucky in that regard! Along with BMW tweaking things at the factory to try to deal with the clunk, dealers also were given instructions on refit kits to try to deal with it - I think my bike may have had some dealer work in that regard sometime in the first 12 years of its life before it went into long term storage for years and years..
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Hello Lads,
I just got an idea !
I looked at the fiche for an R100CS made in 1984 and saw that the fork valve body has two versions: one simple like the R65 original and one double with a spring in between like the LS NHMAF shows us.
Do you think that these parts will fit an R65 fork ?
The parts are not shown as "Ended" although some are not readily available for buying.
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Centre stand springs are on! Great tip. 2 minutes to insert washers. 30 seconds to fit the springs. Rear wheel ready to go on and we're off the floor!
Thanks heaps
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OK, been waiting patiently and received my fork tubes back this morning all nicely re-chromed - beautiful! Reassembling my forks today and keen to get a front end in this bike. All parts cleaned, new seals, new red rubber top stops obtained (and ready to start the process of disintegration inside the forks).
I will say that along the way I learned a great trick about compressing the rings and re-inserting the damper piston, which, otherwise would have been a monumental PITA. Slipped both in on second attempt and pretty proud of it.
But, I have a problem with reassembly. The valve housing (# 21 on diagram above) will not insert into the bottom of one of the fork tubes. One slipped in fine and is all together. I have pinned down that the inside of one of the fork tubes is out of round because I've tried both valve housings in both fork tubes, and both housings slip into one tube just fine, but neither will go into the other tube.
The damper rod assembly all came out really easily so didn't seem to be problem when I dismantled. I've looked for a lip or burr on the fork tube that may be a result of re-chroming, but nothing there.
So, it seems like I'm off to my favourite engineering works (to spend even more $$$) to have the fork tube inside machined to round again. My question is, how careful do I have to be with this? Does the valve housing need to sit snug inside the fork tube, or is it OK if it might end up a tiny bit loose (laterally) and might turn inside the fork tube? I know that shims might be required lengthwise to stop it rattling, but is any lateral movement a problem?
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You can insert the housing from the top, if it won't fit through the bottom .
I had this problem with one of the forks on my '82 LS .
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I wish it would, Bob but on my forks it has to come in from the bottom.
Looking at the fork tube from the bottom, there is a section of the tube which is just the right diameter and length for the housing and the washer above. Above this it reduces in diameter to take the piston and rings snugly. The housing is therefore held in place above by the shoulder where the tube becomes narrower and held in place below by a circlip at the bottom of the tube (which may require shims if the assembly rattles – mine does not). Besides, when reassembling, the piston end of the damper rod has to be inserted before the housing coming in from the bottom.
This is, indeed an ’82 LS, but I understand that the factory put out several different configurations of the forks even in the one year, which may explain the difference between yours and mine.
I have just fully assembled the other fork and on looking at the whole damper rod assembly in place, I think that a tiny bit of lateral play in the housing probably won't do any harm.
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My question is, how careful do I have to be with this? Does the valve housing need to sit snug inside the fork tube, or is it OK if it might end up a tiny bit loose (laterally) and might turn inside the fork tube? I know that shims might be required lengthwise to stop it rattling, but is any lateral movement a problem?
I doubt it's critical to the nearest few thou as long as it remains reasonably concentric. The only time that really matters is when the forks are on full compression and the top hat damper rod seat enters the bottom of the valve body. On assembly you should in any case push the fork leg up to maximum compression and rotate it a few time to centre things up before tightening the damper rod bolt.
Curious how the stanchion bore ended up a smaller diameter. They didn't plate the inside did they ? I can imagine that causing problems with the damper piston rings.
Assuming it's only a few thou that needs to be removed you could just as easily turn down the outside of the damper valve body and you might more easily contrive a way of doing that at home without a lathe.
On the endplay I wouldn't accept anything more than one or two thou as the oil film will stop that chattering. Mine I think was 20 thou and shimming produced a significant reduction in fork noise.
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Thanks Barry, and I'm with you. I don't think a few thou will matter greatly. The stanchion bore is not smaller, it is just ever so slightly out of round. Like I said, the old assembly just came out no trouble so maybe the chromer has done something. The chrome job is excellent and stops at the right place, so this hasn't impacted.
I said my other fork is fully assembled but I struggle with how to get the proper torque on the damper rod allen head bolt. Seems to need some compression to stop the damper rod from turning. You say to compress the fork to maximum compression. Will this allow me to tighten the damper rod bolt? Both manuals I have skim over this point in the reassembly process. Do you have a method for doing this off the bike?
P.S. I admitted up front that I was a novice at his game, but I'm learning a lot as I go.
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I said my other fork is fully assembled but I struggle with how to get the proper torque on the damper rod allen head bolt. Seems to need some compression to stop the damper rod from turning. You say to compress the fork to maximum compression. Will this allow me to tighten the damper rod bolt? Both manuals I have skim over this point in the reassembly process. Do you have a method for doing this off the bike?
Although it can be done by compressing the fork leg the proper method with springs out is to hold the damp rod still from the top using a socket and long extension.
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+1, Time to make a trip to your favorite hardware store and get the longest socket extension they have... or (2)... this is part of the "airhead maintenance initiation"!
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+1, Time to make a trip to your favorite hardware store and get the longest socket extension they have... or (2)... this is part of the "airhead maintenance initiation"!
About a 14-inch extension and the correct socket will do it.
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My socket set has a couple of extension that put together are long enough. Given an adapter no reason why a 3/8" and 1/2" extension couldn't be combined.
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Thanks all. It all sounds so logical when you can tap into the voice of experience. I hadn't even considered this as an option but it's a beauty. And I'm almost certain I have the extensions to do this. Thanks!
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Those old Boge shocks kicking around on the floor... they're not holding the bike over the rear wheel are they? :D
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There's your answer.
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Now you have me thinking. I really can't recall what they were like when the bike came off the road a few years back, and as I have no recollection of them being really horrible, I was just going to tidy them up, put them back on, and use them. Now at the risk of starting a "what is the best shocks/oil/tyres"-type discussion, if these (I assume stock) shockies are pretty bad in the scheme of what's available I really would like to know. Then I can look around for options.
What the hell, I've blown the budget anyway!!
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I took Monte's advice and bought a set of Hagons from Dave Quinn. They were about $230 including shipping. He sprung them at the factory rate, since that will give me an inch of sag at 220lbs. He can put whatever springs would suit you best in your set.
I've noticed a definite improvement in turning. Then again, my Boge's were starting to make crunchy sounds. I still think this is the best the bike has handled, and my back tire is getting pretty squared off.
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I took Monte's advice and bought a set of Hagons from Dave Quinn... I still think this is the best the bike has handled, and my back tire is getting pretty squared off.
"Squared off" you say? More turns, less straights. ;)
I like the way Dave Q sets up the shocks when you tell him, honestly, your ATGATT weight and a few other answers. For the price, they provide excellent control for our Airheads. Also available with spring shrouds, if you like that look.
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+1, Time to make a trip to your favorite hardware store and get the longest socket extension they have... or (2)... this is part of the "airhead maintenance initiation"!
About a 14-inch extension and the correct socket will do it.
13mm (1/2")
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Thanks all. It all sounds so logical when you can tap into the voice of experience. I hadn't even considered this as an option but it's a beauty. And I'm almost certain I have the extensions to do this. Thanks!
If you don't - I do.
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what's available I really would like to know. Then I can look around for options.
What the hell, I've blown the budget anyway!!
Best option in Australia is IKON, these are the old Koni shocks, now made right here in Sydney. Hagons are in the same league in terms of price/performance, but your nearest service depot is overseas. I recently bought Betors on something of a whim and they haven't annoyed me enough yet to either change the damping fluid or "deep six" them, they are a lot cheaper than Hagon or Ikon, but they are not as good either. That said I took a loaded R65 to the Lions Den last weekend and they performed adequately.
On the more esoteric end, apparently Fournales are still available, you would have to sell your most beloved Harley to buy a pair though.
There are cheap YSS copies available on Fleabay, I bought a set and they are actually not badly sprung and the damping is infinitely adjustable (air over oil) - if they had more than 2" of they would be great. If you would like the set I bought - you are welcome to them as a free gift.
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Tony,
Yes, Fournales are still available (I live 10 km from the factory) they are expensive but they will outlast you and the bike. They are totally rebuildable and you can change the oil easily.
You also have EMC in France and Shock Factory the later being cheaper and rebuildable too. They adapt the spring and damping at your request on order. I did not know that Betor was still in the business.
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Tony,
Yes, Fournales are still available (I live 10 km from the factory). I did not know that Betor was still in the business.
I will look to see if Fournales have a website.
And yes I was a bit surprised to find Betor still in business (old jungle saying from the 70s - "betor than nothing, but not by much". I once fitted a set of stock FVQ (themselves known as "fade very quickly") OEM shocks from a Honda-4 to a Bultaco to replace Betors and counted it an "upgrade."
But i am going to have t change my tune. I emailed Betor and told them what i weigh and what the anticipated load on the bike was and they sent me a spring/shock combination.
I'm actually rather pleased with them, they could do with more damping, but it isn't urgent enough for me to start experimenting just yet.
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Tony, the web site is here : http://fournales.fr/
I'm sorry, it is in French only...
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Tony, the web site is here : http://fournales.fr/
I'm sorry, it is in French only...
I actually had a look at it last night and Chrome did a fantastic job of translating it (that's how I ordered Betors from Spain bye the way).
Anyway I discovered that my old mate Bertrand Cadart is STILL the Australian agent after 30 years. I have emailed him and requested a price.
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OK, a few days off-line mostly due to the activity that pays for the fun - work - but some progress on the rebuild today.
Firstly, thanks for your kind offer of the shockies, Tony, but I think I may just tidy up the old ones and see how they go. If they are not up to scratch I can upgrade later. That way I may sneak the purchase past the minister for war and finance as a 'failure' rather than an 'upgrade'.
So, the forks all went back together and the only way I can describe it was "bloody beautifully". Thanks to quality parts, great advice from the forum and 2 X 12 inch socket extensions and a 13mm socket.
What else can I say? Following reassembly of the forks, I've spent today getting to this stage (see photos). Everything is aligned as it should be, turning freely and working like a dream.
I should update a rebuild post I started over in the rebuild section and might do that soon.
Thanks all. You are a brilliant support to a complete novice.