The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: HellBilly on January 29, 2009, 03:28:27 PM
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1981 R65
i recently changed the tires on my R65 and when i was putting the front wheel back in, i noticed somthing just wasnt right. One of the forks appears to be shorter than the other. The axle holes do not line up, and the difference seems to be about 3/4 of an inch, the forks are in the exact same position in the triple trees. the shorter fork seems to collapse and return fine. checked the bolts on the bottom of the forks going up to the dapening rods, and the one on the shorter fork spins freely and will not tighten up. I was wondering if anyone on here has had this problem on an R65 or could offer 2 cents on what my problem might be, before i rip this fork apart >:(
thanks guys
- Jared
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1981 R65
i recently changed the tires on my R65 and when i was putting the front wheel back in, i noticed somthing just wasnt right. One of the forks appears to be shorter than the other. The axle holes do not line up, and the difference seems to be about 3/4 of an inch, the forks are in the exact same position in the triple trees. the shorter fork seems to collapse and return fine. checked the bolts on the bottom of the forks going up to the dapening rods, and the one on the shorter fork spins freely and will not tighten up. I was wondering if anyone on here has had this problem on an R65 or could offer 2 cents on what my problem might be, before i rip this fork apart >:(
thanks guys
- Jared
..."checked the bolts on the bottom of the forks going up to the dapening rods, and the one on the shorter fork spins freely and will not tighten up."
Sounds as if the damper rod in the lower fork body done come undone someway or is, perhaps, stripped. Disassembly is the only option for an inspection but it's not a big deal, really. Weren't you wanting to freshen up those fork seals anyway?
I've heard tell of some R65s having "spacers" in combination with the fork springs. I have an '81 and '83 R65s but neither have the mentioned spacers inside the legs. Point being, if there are spacers in your scooter's legs, you may have one missing/damaged/ or simply wasted. The non-tightening Allen screw is a worry.
Again, disassembly is the next step.
Monte
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yah i know im gonna have to take it apart, i just wanted a heads up as far as what i might be looking for. Ive read that the R65 forks are unusually complicated. Thanks for the advice man.
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Sorry to be of little help, Billy, but as old as your bike is, whenever a system shows a sign of degradation, you should probably plan on rebuilding the whole system - in this case, both forks.
I have never rebuilt forks before, so I can't really say what is involved, but there are plenty of folks here that have.
Please also, do a search for fork rebuild with the search engine. Remember to change the default in the search from 1 week to All Posts. You might also change the pages selected to search from all to just those in the tech section, as well.
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Does the longer fork leg also compress and expand normally ?
If you're going to disassemble the forks, first take off the drain bolts on the back sides of the sliders and drain out the old suspension oil. Note if there are chunks of black plastic or goo in it. You should be able to get at least 150-190cc of oil out each leg. Put the drain bolts back carefully - DO NOT TIGHTEN THEM to the 10 FT-LBS you'll see in some manuals as you can strip the aluminum threads - just snug them up reasonably such that the don't leak oil after you refill everything.
Don't give up hope yet - the allen bolts on the bottoms of these forks can do what you describe (spin around without seeming to tighten)if the damping rod assembly inside the fork lowers is also turning. IF you haven't been getting oil leakeage out that bottom bolt hole, then the bolt is indeed tight (or you have somehow already lost all the oil in that fork leg). To loosen/tighten that allen bolt to take the sliders off for disassembly, you'll have to take the top cap off the fork leg. Inside there is a metal "plug" which is retained by a circular spring retainer that fits in a groove milled into the interior of the fork tube. You have to push down on the plug (against the pressure of the spring) to get it far enough down below the retainer so that you can pry the retainer out of its groove with needle nose pliers and/or small screwdriver. DO NOT LOSE IT!
Also, be careful letting the pressure back off the spring unless you want to catch the metal plug in your eye..
Usually the spring pressure is enough to pop the plug out the top but sometimes it may get a little tipped to the side on its way out and hang up inside the tube - just push down on it again and let it up until it comes free. If the spring inside is broken, it might not pop up - and that could be one possibility as to why one leg is longer than the other.
Anyhow, pull the spring up out the top of the tube. It it is an aftermarket spring, you might find a plastic PVC spacer in the tube as well. NOW that you've finally got all that out of the way, you will need a socket wrench with a looong extension on it to reach down into the tube and grab onto the nut at the top of the damper assembly. I *think* that the nut size is 11mm, but my memory isn't good at the moment. Holding the socket wrench at the top from turning, you can now go back to the Allen bolt at the bottom (remember that is what got us started down this path?) and you should be able to loosen it while holding the other end of the damper tight with the socket wrench. This all seems like it requires a 3rd hand, or a second person to help, and sometimes it does. Once you've got the bottom bolt loose I will usually take the fork tubes off the bike so I can lay them on a bench, slip off the dust caps from the top of the sliders, and slide the tubes and internal damper assembly out from the fork sliders/lowers.
There is supposed to be a bit of spring pre-load in these forks - dpending upon the length of the springs installed one needs an appropriate spacer or you may here alot of clunking/noise happening when the fork compresses/extends. The Progressive spring kit I installed in my 82 came with 1" spacers to get thr right amt of preload.
Keep us posted and we'll try to help you out.
[smiley=thumbup.gif]
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Hey thanks man, that is a big help. I changed the fork oil last summer. nothing nasty came out. I DID pull some bad ass wheelies with it tho, haha. I guess we'll see, might be time for some progressive springs.
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I am in the middle of rebuilding both forks on my '83 R65, currently awaiting arrival of new seals, caps, and washers. I could take some photos of what is involved while they are all apart, and post them if anyone would be interested. Is there a place on this forum for such photos?
Anyway, it would have to be in the next day or so, as I'll likely re-assemble them as soon as the new seals arrive.
Let me know.... [smiley=smiley.gif]
PS - The rebuild undertaken not only to replace leaking seals, but also to remove some awful stiff aftermarket heavy-duty springs! They're 19.5" overall length (un-compressed) with extra thick wire diameter (25.3 mm instead of 25 mm) and tightly wound for first inch top and bottom. They will likely be for sale next week....so, if you're needing heavy duty springs....packing lots of gear, or riding double mostly, let me know.
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that would be cool allred, thanks man!
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I managed to fumble my way through this fork disassembly once with the help of the fellows here. I never knew about the need for the looong socket extension and how you had to hold the inside bolt or nut with, I think, a 13mm socket while you loosen or tighten the big bottom nut. One side never needed this procedure to tighten up to torque. Anyway, I did use some duct tape to tape the socket to the extension so it wouldn't drop off inside the fork tube! :o I did have a third hand too!
I thought I had stripped that bottom bolt and I remember just starting to cry on my knees in frustration :-[ All ended up Ok in the end. :)
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One of my R65s is an '81 model. Here's some info from a couple posts I did on overhauling the forks.
The correct socket required to hold the damper is a 13mm. I used a 0.25-inch drive with fourteen inches of extensions to reach and secure the damper rod.
Note the circlip that holds the aluminum fork cap in place. I was confused on its correct removal procedure until I tried it. Read my post for some tips. My wife was quite helpful while serving as the Pusher Downer during dis- and re-assembly.
Again, H'Billy, it's not difficult.
Monte
http://suraklyn.com/yabb/YaBB.pl?num=1209318270/0#0
http://suraklyn.com/yabb/YaBB.pl?num=1209605080/0#0
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Allred,
Photos of your fork components while you have them disassembled would be much appreciated! I replaced my fork seals a couple of months age and only took the sliders off of the bottom of the fork assembly, so I didn't get a first hand look at the internals of the upper fork.
My left fork had been leaking for a long time and things were really cruddy inside and out. So cruddy in fact that they didn't even drain when I took the bottom plugs out. I had to use a wire to punch through a sludge layer to get the old oil to flow out. The sliders cleaned up fairly nicely using denatured alcohol and a rag on a broomstick to get down to the bottom. It's great now having a dry front end!
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OK, here is a photo of the fork, completely dis-assembled, and parts laid out in approximate order of their assembled relationship.
This forum doesn not allow large photos, or at least I can't figure out how to post them, so hope this small size still shows enough detail to be useful.
[smiley=smiley.gif]
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Thanks Allred! Drawings and exploded diagrams are great but there's nothing like a photo of the genuine article!
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...My left fork had been leaking for a long time and things were really cruddy inside and out.
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fi196.photobucket.com%2Falbums%2Faa1%2Fmontmil%2FBMW%2520R65%2FP4270002.jpg&hash=2935d5291a5661285fa2ce9a881ec38db3299d3c)
Off my '81. I've been told that this silt is not that unusual. Still, it's nasty and quite the surprise to discover.
Monte