The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Darwin_R65 on March 22, 2009, 05:16:46 AM
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OK nothing like finding only a single problem when something goes wrong. And this is nothing like that.
I've reassembled my rear wheel after greasing the spline with a moly grease, and go to adjust the rear brakes and "click" the brakes lock on. back the brakes all the way off and the wheel eventually frees up and then repeat and same thing.
Pads look a little worn but nowhere near enough to be a problem.
But the shoes don't really seem to sit on the cam as snugly as I would expect.
My bikes manufacture date is 10/1980 and looking at pictures and catalogues that state the brakes changed 09/1980, it appears I have the right shoes.
Could this be my cam is worn? Aftermarket shoes made by dodgy brothers?
Anyway it results in If I apply the rear bake firmly, they lock on and stay on, as the cam rolls too far around.
Or is this the way it's all meant to be set up and maybe my drum has been skimmed a little too much over the years?
John
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The lower shoe looks like it's not installed right. Can you post a pic showing both pivots at once? I thought the shoes had different ends.
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Maybe this photo will help?
http://www.motobins.co.uk/displayfinal.php?function=show&subs=102b&title=BRAKE+SHOES%2FSPRINGS
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Here is a pic of my rear brake shoes installed - one thing I noticed is that one can end up with the ends of the shoes that pivot on the common "bolt" (toward left/bottom of pic) a bit misaligned in which they don't properly pivot and might either bind up or not travel properly.
IT does look like your cam is a bit worn from the photo, though I don't know if it is too worn.. hmmm.
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fi159.photobucket.com%2Falbums%2Ft138%2Fnhmaf%2Frearbrake01.jpg&hash=a51a18ece49c42ebb9100e344b58b7339858e3cd)
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Umm - IMHO I think it is time to replace the cam... and I agree with Ed - the ends don't look quite right either.
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Is it possible to get the two shoes mixed up? I don't remember.
nhmaf's bike must be an LS....
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Yup, mine is an LS, but I think it is mechanically identical, save for the larger diameter. There IS a top shoe and a bottom shoe - otherwise the overhang isn't correct to mate with the cam, which is supposed to engage in one direction and disengage in the other. I don't think that I can get mine reversed top-bottom, but if I could then it would try to disengage when you stepped on the brake and engage when at rest ?
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The cam should not be able to pass the end of the shoe. It could be the wrong cam if the final drive was replaced, the cam could be worn, or the shoe could be bent (unlikely). Ordering a new cam would be my first move.
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In the first set of photos,there is a difference in the shoes.
There is a difference in the length of the straight section of metal that contacts the cam, one is significantly longer than the other.
Looking at the installation on the LS, both shoes look to be the same dimension.
I would suspect an incorrect part, or more likely at some point in time some 'adjustment' has been made to the lower shoe.
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I think that Bob may be on to something - perhaps if you could take your shoes off and examine them for part numbers ? I am thinking that maybe a PO had replaced the bottom shoe with one for an LS (which take a slightly bigger shoe as the rear hub area is slightly larger in diameter). If the lower shoe end were a bit shorter it might not go past the end of the cam - it's a thought anyhow.. But, the ends of the cam in Darwin's picture do appear to be more worn down than in mine also.
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According to the motobins site posted above, the LS has different shoes than the regular R65s, and the pictures of the regular R65s were like the ones in Darwin's pictures. I'll be changing tires in a few weeks, but I don't feel like pulling my rear tire for a look until then. Sorry. My bike is only a month newer, so I bet I'll have the same brakes as Darwin.
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Those are LS shoes in NHMAF's pic. [stare and compare] They are positioned correctly [top & bottom are slightly different]
rich
LS Shoes
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fwww.motobins.co.uk%2Flibrary%2F24810.jpg&hash=3c34b8c8ab808e0429b10a2786253571d44d828a)
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I guess that I shouldn't have assumed that a pic of mine would help anything ! I do know that the LS shoes are slightly "bigger" due to the differences in the rear wheel (snowflake .vs. LS) housing diameter, but I thought that the relative sizes from top/bottom where the same as compared to the snowflake wheels, but that is my bad, I guess.
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A few pictures from my '79. Click to make them larger:
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fwww.pbase.com%2Ftomfarr%2Fimage%2F98904503%2Fmedium.jpg&hash=aec43337b8e3808853bc27c44283332b1aea645d) (http://www.pbase.com/tomfarr/image/98904503/large)
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fwww.pbase.com%2Ftomfarr%2Fimage%2F98904504%2Fmedium.jpg&hash=11fb9d3417cdf18d9e4e774cf0dfe832b363290f) (http://www.pbase.com/tomfarr/image/98904503/large)
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fwww.pbase.com%2Ftomfarr%2Fimage%2F98904506%2Fmedium.jpg&hash=d0d1a0e31cc6f338848af04bc25d3a7136f3d965) (http://www.pbase.com/tomfarr/image/98904503/large)
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Compared to Rob's pics, the ends of the shoes on Darwin's bike don't seem to be in the right place? Maybe they are the wrong ones, or that cam is really worn down?
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Yes looks like he has the '81-on shoes. The '79-'80 show this. Wouldn't a 10/1980 manufacture date make his bike a '81 model though?
rich
(https://bmwr65.org/smf/proxy.php?request=http%3A%2F%2Fwww.motobins.co.uk%2Flibrary%2F24700.jpg&hash=6e91f8573a789d9b5f75a6a7edb3801064c8f4ca)
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Yes, the production of the model year starts in late Sept/early Oct of the year before, so they should be '81 shoes and cam, etc. But, maybe there was a leftover part or two in the bin when the production line started up? OR maybe a PO substituted some parts? I don't see how that rear brake cam could get so worn down under normal conditions unless the bike was ridden 100K+ miles and/or the rider loved to lockup and skid the rear tire at every stop sign/intersection?
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Hi
This is a picture of my rear brakes from the '81-'84 model. Neither shoes nor cam are worn, as they are from a rear drive from an R45 with a low milage. They are identical with the R65 brakes.
greeting from a 90% clouded normal temp. 50 F north
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Good picture, Trolle, thanks. But flipping back and forth between Darwin's pics and yours, all I can think of is Darwin has the shoes in wrong, probably on the pivot end that isn't in his pictures.
Hmm, he hasn't posted again to this thread. Is it fixed?
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It's not that it's fixed, but sometimes work sends me away.
I been in Gove working, (A small mining community in remote Northern Territory) so haven't had the chance to come back to the bike. Nice to see so many interested people. I put the rear wheel back on because I've got little kids and I don't want bikes falling over. I'll try and pull it off again this afternoon and have another look.
I have made sure the pivot is seated correctly, that was my first thought. When I pull it off later, I'll measure a few more things.
Because of the distinct difference in shoes, I'm definite I have the 1981 shoes. I guess it could it be possible my bike was made with the 1980 drive unit, or a PO has changed things. My Valiant has shown me that PO's can be very creative in producing non standard repairs that simply don't work, but that's another story.
John
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p.s. Living in Darwin I'm unaware of any other R65's here, and parts are 4000 kms away in either Perth (new parts ) or Melbourne (wreckers). Unless Aussie can tell me of some BMW goldmine in Adelaide.
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Right I've pulled the rear drive apart.
following are some photos with measurements
but first one to show the shoes are on the pivot correctly, I've removed springs in this photo so I can show the cam in it's operating position.
the second photo shows I've measured from the outside of the pivot side of the shoes.
The third photo shows my measurements. (camera angle is a bit off causing parallax error)
the smaller shoe measures 150mm inner edge to 156mm outer edge.
the larger show measures 180mm to the inner edge and 186 to the outer edge.
my pivot post measures 12.8mm diameter.
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And my brake cam measures 30.3 mm x 19.3 mm
If anyone could measure theirs it would be much appreciated. I have a had a thought it is possible the previous owner may have replaced something with the wrong year.
And from the centre of the pivot post to the centre of the brake cam is 155mm
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And the rear drive unit plate has the part number on it 1238834
and has a circle with an 81 above an 80, which i assume refers to the year, so I guess the plates the right year. It's just the cam I don't know about. So if anyone has a post 81 model bike and you could measure your brake cam that would be fantastic.
John
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Measurements of my LS won't help BUT I am finding multiple part numbers for the brake cam. The plot thickens
http://www.webparts.com/diagram.php?btnr=34_0599&mospid=47851&hg=34&fg=10
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The part number that ends in -261, is for the '78-'80 model year bikes.
The part number that ends in -836, is for bikes made 09/80 and after.
After 29 years, and multiple owners, it is possible that incorrect parts could be installed !!!
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I am so far unable to nail down the part number shown on the cover. What it looks like in the pic is 1238834 along with 11 and 225 below. no matter how I try I cant make a valid part number out of these but I'm no wizard at changing part numbers. Ive also found multiple listings for the pivot pin and cover. still trying to werk this puzzle out. All I do know is that pre '80 drives don't play with post '80 drums but there is a mod. Need to nail down the hub cover & drum year then figure out the right shoes $ other bits. The cam may be only part of the puzzle.
rich
[smiley=wall.gif]
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Not uncommon to have what appears to be a part number cast into the metal, that doesn't correlate to any available part number.
Most likely it is the company that produced the part, has their own numbering system, that has nothing to do with BMW part numbers.
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A lot of the time these esoteric numbers are date codes, shift codes, etc., so someone who know tyhe code can tell exactly when it was cast.
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Just to let you know I finally got around to getting new brake shoes and putting them on today, and yes there's about 5 mm difference in diameter of the shoes.
Why has it taken me so long?
I renewed the spline on the rear drive at the same time, had to order it, Freight to Darwin is by camel I'm sure.
Engineering shop took two and half weeks to replace spline in crown wheel.
Then had to find some time in between work, kids and the wife all demanding time.
So today I dedicated to returning Norma back to the road where she belongs and I get it all together and go to put oil in the rear drive and the level plug is stripped. BUGGER.
Pull it all apart again just to get the plug out with a punch, hammer and unscrewing the bolt all at once.
Sunday on a long weekend, off I trot to Independant motor mart, any helicoils? what size? I say metric 8mm, and can't remember the pitch I say it's the fine metric, well this confuses the girl who asks if it's a special thread that's a cross between metric and UNF.
I look at the sample bolts on the display and correct my statement to M8 x 1.0. She's still lost. Feel like banging my head on the floor.
She looks up the catalogue and says "we have M8 x1.25 if that's close enough." Impulse to headbutt wall gets greater. I actually thank her for her help and walk out. Try supercheap autos and they don't even stock helicoils. Aaarghh, the frustration of trying to fix bikes on weekends.
So a day spent putting the bike together driving around in the car, headbutting walls and pulling the bike apart again, and me wondering just what did I achieve today. Bike is in same condition as yesterday except I now know I have a thread to repair.
John
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A lot of folks will tap it for a "pipe thread" (or slightly larger straight thread) and put in a brass plug like the PO did on my LS project:
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Please, Justin! Cover those wheels as there may be young children about. Oh, the horror...
Monte
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You are more than welcome to come over and make them a bit more presentable.
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Hi John,
I work in China, try doing all that and not being able to understand the language and you will understand why I rarely smile these days.
Go buy yourself a thread gauge, very cheap, and easy to use. They little arms fold out and there are about 20 different threads sizes with every gauge.
I can send you one from Brisbane when I get home in a few weeks if need be of course, but Repco or Supercheap will have them.
Read the plug and then do the helicoil trick, there are many alternatives to helicoils too now, so try one of the marine dealers locally, they will have the stainless steel kits in hand.
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The advantage of doing somehting yourself on the bike, is It's cheaper, I can guarantee what work has and hasn't been done, and I can usually guarantee it was done corectly.
The disdvantage is that sometimes it takes me forever to finish.
I have finally got my bike back on the road, after deciding on 22 Mar to fix my brake problem, and rear drive unit spline.
Brakes I just replaced the shoes.
Spline, I mortgaged my first born child. $310 for the spline, $220 to get it welded onto the crown wheel.$123 for the bearing.
Labour chewed up quite a few wife brownie points in "I know you need help with the kids but i need the bike back on the road" Fortunately last night (And we have two extra kids this weekend, we're doing respite) the kids were all tired and went to bed early and i had a couple of hours to do the job.
Went for a ride and it was sweeeeet :D to be back on the road again, however my battery was flat and I had to jumpstart the bike.
Ahhhh to me mobile again. :)
Thanks to every one who helped with technical advice on this one.
John
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Cheers to another successful fix and a happy ending! [smiley=beerchug.gif]
P.S. This thread, especially the photos, was of great help to me replacing the seals on my cam, stopping the gear oil leak that was soaking my brake shoes and giving me functioning rear brakes again.