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TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: i-man on September 07, 2014, 02:48:19 PM
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First post, I wish it were under happier circumstances.
i've been interested in the k bikes after owning a series of R bikes. A 1990 k75s, pretty rough, 90,000 miles, the clutch was out, the price was low enough so I thought I'd roll the dice...... Snake eyes.
the final drive splines aren't good, but i'd probably run them, the out put splines on the driveshaft are fried. The input splines are okish and I'd probably run them for a while also. the other splines all look fine, but not great.
the fiction disk basically exploded. it looked like a bird in a blender in the bell housing. just replace the friction disk? Whole pack?
The magnetic drain plug for the trans was quite fuzzy.
Here's what I'm thinking.......
Figure out what parts to sock away and part out the rest. I don't really like that idea, but i'm starting to warm up to it
Send the final drive and shaft to bruno's. don't like that idea cuz those parts would be worth more then the rest of the bike, which seems absurd.
go shopping for used parts. This is the one I like best, if I can get usable drive parts for under $400ish. Are monolever k75's and k100 final drives, driveshafts, and clutches interchangeable?
i'm pretty set on the k bikes (75 or 100) but i'm starting to think this one might be more touble then it's worth.
What say you all?
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I can't decide for you what to do with this mess, but could add that 75 and 100 clutches is different.
Other parts is interchangeable, exept very early K100 FD's and driveshaft have 16 splines and not 20.
And of course you got a lot of different ratio at the FD's.
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Personally, I would put myself firmly in the 'fix it up' camp - if it were mine.
My K75 has a (later) K100 32/11 final drive and it goes fine, doesn't feel overgeared or anything. You do have myriad options though - afaik any K75/100/1100/1 gearbox will go on the back of the engine, then stay monolever or go paralever (see Inge's caveat about 100 shafts). I'm also pretty sure the R series arms/shafts interchange as well so that's another availability option. Depends how much time you have to experiment - if you buy smart price wise then even if something ends up not fitting you shouldn't make a loss.
I don't know what the parts market is like over there, but here you could do it fairly easily for well under that money with a bit of searching - a monolever 'set' goes for about the same money as a paralever setup here, it seems as if the paralever parts set the price for the monolever ones. People 'upgrade' to para and want to recover the money by selling the mono parts for the same price...
I'm pretty sure you can't get a 100 clutch to fit on the 75 flywheel (they are different as Inge states) so you're either finding a 75 clutch or attempting to get a 100 flywheel on it too (no idea if it's a viable idea). You could get away with just a friction plate if the rest of it is in decent nick.
K and R series bikes are almost unique in their almost 'meccano' design and build where you can unbolt stuff from one bike and bolt it up to another.
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thanks for the reply's.
I'm really hoping to get it on the road.
Pdg- are you talking about R bikes meaning early Airheads, or contemporary R bikes?
I'll add that the WHOLE point of having this bike is to serve as a tug for a sidecar. Does that make one or another gear ratio better or worse?
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I've pulled a sidecar many thousands of miles with k75s but having the extra cylinder on a k100 will definitely give you some added oomph - I've heard that is much more important than the gear ratio. At freeway speeds the 3 cylinder is really working. Then there's some issue with k75s having some kind of built in steering damper while k100s have none...I don't know much about that though. I will tell you that with a k75 and no leading link you will be constantly muscling to keep it on the road. I got used to it but don't expect an easy ride.
There's a whole thread on the merits of replacing the entire clutch pack vs just the friction disk. In your case if the disk exploded I would want to closely inspect the entire clutch assembly to find out why. Search for the thread...it's pretty recent. You must replace the clutch bolts and washers tho every time you pull the clutch, they are basically single use.
What you get on ebay in the way of final drives and driveshafts is a crapshoot. You're better off with what Duck has to offer on kbikeparts.com, you will pay for what they're worth with Duck rather than paying for what the seller can get on ebay.
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The K75 has a 'fluidbloc' steering damper that lives in the steerer tube - if you don't want it there then take it out (while you are inspecting the bearings..)
Lower gearing might help some, if you have a choice of final drives go for one with a bigger bigger number and a smaller smaller number if you can (like 10/33 instead of 11/32) - some parts internally will swap.
By R bikes, I meant a selection... Monolever and paralever parts are essentially the same (watch for rear shock position if you go 'newer', plus the shaft is on the other side on some of them) and I'm not sure if the old style double sided airhead swinger will go in. (Well, it could, because anything could ;) )
If you're not planning on racing with the chair on, a 75 should tug it along just fine. Consider that the 75 has more horsepower than just about any of the early BMWs that had sidecar lugs welded on the frame from the factory.
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yes, the sidecar was meant to be pulled by a /2, so the k75 should be fine!
i bought a driveshaft off ebay lastnight. I didn't know about kbikeparts. I'll look it over and if it's not up to snuff, I'll return it. I think I'm going to run with the final drive I have. The splines aren't terrible.
as far as the friction plate vs. the whole pack, how best to tell if the other parts are damaged? They LOOK ok, but I'm sure that's not the best way to tell if they ARE ok.
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as far as the friction plate vs. the whole pack, how best to tell if the other parts are damaged? They LOOK ok, but I'm sure that's not the best way to tell if they ARE ok.
There might be info on that in the Lieberry...if you find any out there send me the link because I'd like to know that too!
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Have a good look at the parts, after you have cleaned them very well indeed. You should be able to see any wear witness marks/ridges etc. Some wear is to be expected, but it's up to you to decide how much is too much (or try and find specs). Any hint of any cracking then scrap them. A little bluing probably won't hurt, if it's not too deep a colour.
If they really DO look ok, then they more than likely are ok - but it needs a damn good look.
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I'd like to know whether the clutch spring can lose its springiness over time. I have a symptom which would seem like the spring isn't doing what it's supposed to do...seems like the clutch stays engaged when you pull the lever in...there's some engine braking going on that lasts a couple seconds then it frees itself up. I can free it up by releasing and pulling in the lever quickly just enough to make contact, then whatever it is that's keeping it engaged releases and it goes to free roll. Clutch cable is new, so it's not that.
Maybe this is worth a separate thread...anybody got the skinny on spring wear? Mine is ancient.
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Any spring can take a set given time (or 'lose it's springiness' if you will).
Because I don't know how much you know, I'll start at the beginning (relatively speaking)...
The primary job of the clutch spring(s) is to hold the clutch engaged and allow it to transmit drive. When you pull the lever you are acting against the spring pressure. From what you describe, your spring is doing exactly what it is intended to do. A weak and/or broken spring would cause slip.
If your clutch is dragging, especially while driving but not necessarily when at a standstill, then the prime suspect imo would be the friction disc binding on the gearbox input shaft splines. Second would be contamination of the pressure and/or friction plates causing them to stick together. Most of the viable candidates require removal and inspection though.
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Thanks, pdg, very enlightening. I wonder if it might have to do with the fact that I didn't replace an oiled friction disk but rather cleaned and sanded it. Maybe I over greased the splines during the last lube? Either way, it doesn't happen all the time and doesn't bother me, and I don't think it's causing any damage, so I'll just live with it and take a look at the next spline lube.
If the disks are binding, will not the greased material eventually wear off -- or maybe it's been transferred to the pressure plate? Maybe that's why dealers say you have to replace the friction disk after it gets oiled. But I know I'm not the only one who has reused after a greased clutch issue.
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Gambling.That's the theme of this thread. I'd love to replace every little part I think is even a little questionable, but that's not in the cards for me. So I replace what I know needs replacing and hope for the best. I'll certainly follow up and post how that works out. I get the rest of my parts tonight, so hopefully i'll get it back together by this weekend.
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If the friction disc gets oil or grease contaminated then slip and judder is the most likely outcome - replacement of an oiled plate is recommended because the oil will soak throughout the friction material (it's usually somewhat porous) and the slip/judder might not disappear until the plate is worn out or replaced.
Replacement is easier than trying to get the oil out...
Oh, and while replacing every even slightly questionable part might be 'nice', it would cost more than a brand new bike most likely. Safety critical and broken things first, then see what happens is definitely the way to go :2thumbup:
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i hate it when you go to a forum and you read back over old threads and they just dead end, so I figured I'd update this one. I've only ridden the thing less then 100 miles since the clutch work, so it's a little too soon to declare ' mission accomplished ' but everything seems to be working well so far. maybe it'll blow up in a couple of weeks and i'll wish I'd dropped as much as I needed on every part in the clutch basket, instead of just replacing the friction plate, but I'm feeling optimistic about the 'Gamble' so far.
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greetings i-man...
ride it... it has soul... and wants to be ridden...
j o
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i've been really digging it so far. Besides the time today I was making a left turn from a stop and stalled out, causing me to drop it in the street :dunno. man that thing is heavy to lift off the ground!