Waiting for parts or a tool sucks and I hear you about small town hardware stores, they never have everything on the list and that thing they don't have is usually the most important thing. Anyway when you get all this behind you I'm pretty sure your clutch will be secured well enough for years of service if mine and the amount of use it's seen is any indication. My old mountain bike is down for a few days as I popped a couple spokes when I went out for milk yesterday. That back wheel was pretty much used up in the first place so I have to build a new one...which will give me the opportunity to do some regular maintenance and cleaning on the other important parts. I'll take some good photo's of the clutch stuff while I have it apart this time.
Centrifugal clutch blues
- Thread starter silverbear
- Start date
Rockenstein,
I think, too, that this is going to fix it and that all will be well. I have two bikes down waiting either for parts or in the case of the Elgin, tools. And the weather is perfect with trees leafing out, wild flowers coming into bloom and the mountain road calling out to be ridden. Ah well, as with you it gives time to attend to other things such as maintenance and fabrication. Below s a picture showing the key way on the crank shaft, obscured by grease and filings until I cleaned it off a bit. For the benefit of others reading this thread.
And as Elmo wisely pointed out, I have increased my knowledge about the clutch, learning new and useful things. And I have also learned about the diamond tipped dremel attachments which are going to be handy for other things in the future. One bit of knowledge leads to another, just as your juice can gas tank has led to other uses for the lowly tin can. A case in point is an air cleaner I made today from a tuna fish can and a stainless steel pot scrubber. It is pictured below and I like it. I'm not a big fan of plastic, especially on a 1939 motorbicycle, but I'm a cheap son of a gun. I have become a kind of tin can expert, studying them as I shop for food. Everybody else is shopping for groceries while I'm also in the bicycle supplies aisle. Ha! Thanks again for your help.
SB
I think, too, that this is going to fix it and that all will be well. I have two bikes down waiting either for parts or in the case of the Elgin, tools. And the weather is perfect with trees leafing out, wild flowers coming into bloom and the mountain road calling out to be ridden. Ah well, as with you it gives time to attend to other things such as maintenance and fabrication. Below s a picture showing the key way on the crank shaft, obscured by grease and filings until I cleaned it off a bit. For the benefit of others reading this thread.
And as Elmo wisely pointed out, I have increased my knowledge about the clutch, learning new and useful things. And I have also learned about the diamond tipped dremel attachments which are going to be handy for other things in the future. One bit of knowledge leads to another, just as your juice can gas tank has led to other uses for the lowly tin can. A case in point is an air cleaner I made today from a tuna fish can and a stainless steel pot scrubber. It is pictured below and I like it. I'm not a big fan of plastic, especially on a 1939 motorbicycle, but I'm a cheap son of a gun. I have become a kind of tin can expert, studying them as I shop for food. Everybody else is shopping for groceries while I'm also in the bicycle supplies aisle. Ha! Thanks again for your help.
SB
Attachments
Rock,
The diamond burrs arrived yesterday and I just now tried out one the same width as the key. It is going to cut the slot fine and is actually a little faster than I imagined it would be. Question: I'm assuming this slot is absolutely parallel to the crankshaft, is that right? I ask because the photo of yours makes it look kind of like a diagonal, but that doesn't seem possible. I only want to do this once and want to do it right.
I'm so glad to have these little burrs. I looked on ebay and two of the dremel burrs without shipping were $12.00. I got this kit instead with diamond burrs in a variety of sizes but all of 1/8" shank (so I didn't have to change the chuck on my dremel) and paid $14.00 with shipping. Good deal and I'm sure I'll find many uses for these through the years. For that alone I thank you.
SB
The diamond burrs arrived yesterday and I just now tried out one the same width as the key. It is going to cut the slot fine and is actually a little faster than I imagined it would be. Question: I'm assuming this slot is absolutely parallel to the crankshaft, is that right? I ask because the photo of yours makes it look kind of like a diagonal, but that doesn't seem possible. I only want to do this once and want to do it right.
I'm so glad to have these little burrs. I looked on ebay and two of the dremel burrs without shipping were $12.00. I got this kit instead with diamond burrs in a variety of sizes but all of 1/8" shank (so I didn't have to change the chuck on my dremel) and paid $14.00 with shipping. Good deal and I'm sure I'll find many uses for these through the years. For that alone I thank you.
SB
I cut the slot 3/8" deep and the full depth of the keyway which is a bit less than the length of the key, so I ground off each end of the key and also had to grind down the long flat edge a bit. I found it difficult getting the new slot lined up and several tries did not work. With each try the key was pushed out of the keyway in the cranfkshaft unbeknown to me until firing up the bike, trying it and taking the automatic clutch off again. The last time I tried I believe was successful as I road a bit up and down the drive and it seems to be working. Since it was almost dark by then and my lights are not hooked in to the magneto yet I'll wait until tomorrow for a longer run. But all indications are at this point that it is fixed... wahoo! I did take a couple more photos showing the new slot in the adapter which I'll post soon. Cutting the slot did take a good while and I destroyed one of the diamond burrs in the process. In the future I will check the bolt, shorten it, apply locktight and make sure it is good and snug before ever running the motor. I would suggest that for anyone with one of these automatics. Maybe yours will never come loose anyway, but if it seems to be slipping shut it down right away and walk the bike home. Running it while slipping isn't going to do anything besides eat metal. You might catch it in time to just tighten the bolt without having to make this keyway modification. But if you do have to do this fix, now we know how. Thanks again, Rockenstein.
SB
SB
Thanks Elmo. Haven't gone for a ride yet today, so the fix isn't exactly official until it has some miles on it. Here are two photos from yesterday. One shows three woodruff keys, with the modified one in the middle and is shortened at both ends. After this was taken I also ground down the long side a bit for a fit. The other photo shows the new slot or key way in the adapter.
And I do know a lot more than I did a few days ago so as long as it works I'm not sorry about it breaking down. That's how we learn things... with a little help from our friends.
SB
Attachments
Well, I may have bent the nail or something. I didn't get a chance to go for a ride until late afternoon and it seemed fine at first, but then was slipping again. I don't know if the woodruff key wasn't really in the keyway and got pushed back as I slipped the adapter on... but maybe was temporarily wedged or something. I haven't given up, but admit to being a little discouraged. I have a lot of garden work right now for the people I caretake for, but hope to work on it again today. I think I may pick up a couple more of the #2 (3/8") woodruf keys to fool with. I wonder if so much metal was removed due to slippage/grinding that there is just too much slop in the adapter now. I hope not. I don't know if replacement adapters are available as a last resort, but may contact Rick at BGF to see. I would hate to shelve this motor as it is such a good one in every other way. I'm also wondering if this engine could be adapted to a standard clutch if a replacement adapter is not available and if I can not repair this one. A lot of don't knows at the moment, but I am not giving up and will see if I can make the key work with what I have. I'll let you know what transpires.Looks and sounds like you nailed it Silverbear...good job and happy riding
SB
Unfortunately if the adapter is really sloppy on the crankshaft a new adapter won't likely be the fix. Since the crankshaft material is unhardened it is the part that would have been machined by the hardened adapter when things were slipping. Do you have a vernier caliper or micrometer? If so measure the end of the crank that the adapter slips over and I will compare it to mine.
Last edited:
That doesn't sound good. I didn't have a chance to tinker with it today, but did pick up a couple more woodruff keys and hopefully can give it some time and attention tomorrow. I don't don't have anything more accurate to measure with than a ruler/tape measure. I'll keep trying. I have a feeling the adapter didn't get that badly milled. It would have to be a lot, I would think. Thanks for your help.
SB
SB
Rockenstein,
I'm still having trouble with the automatic, but will go into that later. I have a second automatic which is new and just got it going yesterday... went 20 feet and it stopped engaging. I contacted the seller and got a response with suggestions in broken English for fixing it maybe. I would like to forward the email for you to look over if you are willing to. I can't make much sense of it, but it may make better sense to you. If you're game for looking, please PM your email addy so I can send it to you. Many thanks,
SB
I'm still having trouble with the automatic, but will go into that later. I have a second automatic which is new and just got it going yesterday... went 20 feet and it stopped engaging. I contacted the seller and got a response with suggestions in broken English for fixing it maybe. I would like to forward the email for you to look over if you are willing to. I can't make much sense of it, but it may make better sense to you. If you're game for looking, please PM your email addy so I can send it to you. Many thanks,
SB
You can get some from your dentist. And they are diamond. Just depends how well you know him. They can save the old ones for you.
You know, I was joking, but that's a great idea. I know my dentist quite well and helped buy his last truck for him. We're friends and I've known him for many many years, so I will ask him what he does with the old ones. Ya never know. Thanks for the tip... it's a diamond. Ha!
SB
Here's an update on the 'fix'. As mentioned earlier, it seems like I get the bike fixed, it runs great down the mountain and through the flats, I turn around to come home (don't want to get too far away until I know for sure all is well) and start climbing... climbing... slipping... motor revs are changing... more slipping... and I push the bike the rest of the way home. This has happened a number of times. When I open things up for a look the woodruff key is always lying somewhere other than in the key way and I try it all again. The problem is that you can't really see what you're doing. You align things as well as you can and as you push it home the view gets obstructed and you can't tell if the woodruff key is where it should be or not until you try it. It always works great for a mile or two and then slips again. At first it is tight and then loosens. Very frustrating. I got the not so bright idea that maybe there is now so much slop that a bushing of some sort is called for so I tried some JB Weld coating both the adapter hole and the crank shaft where the two meet, joined things up, tightened the bolt home and let it sit for a day and a half, wanting to be sure the epoxy had set up. This last ride went well for awhile and now slips again. When I tried to take off the adapter to clean up what I pictured would be a mess in there I discovered I couldn't get the clutch adapter off. So I need a clutch puller which I don't have. I have to get one for the other automatic anyway, so will wait until I have a puller and then keep trying. If worst comes to worst I will attempt to change it from an automatic to a manual clutch. So, I have two great bikes with motors that run really well, new paint on both, new wheels, etc. and can't go riding. Unbelievable. I'm hoping this story eventually has a happy ending.
SB
SB
any one of you guys have the problem of the whole clutch wobbling badly?
mine does thats why i ask.. when i put the hat bushing on over the crank shaft its completely butted up to the lip on the crank so i think its a bad bushing it still works.. but wobbles alot... just wondering if anyone else does this
mine does thats why i ask.. when i put the hat bushing on over the crank shaft its completely butted up to the lip on the crank so i think its a bad bushing it still works.. but wobbles alot... just wondering if anyone else does this
question for you guys.. i have a centrafrugal.. but i noticed someone said the woodruff key... you cant use that on this clutch it uses pressure and a bolt to hold it in or am i wrong...?
i got one used off a guy.... it works and i have 20 miles on it.. it clatters like a normal clutch but just wobbles like no tomorrow.. wondering if thats normal for these.. also i have 1/2 spacers to fit the cover..
im wondering if i got a bum one.. i have a ht engine.. and the hat sleve buts up as far as it will go to the crank sleve but only till it hits the crank lip so it sticks out to far.. id have to machine it.. thanks for any help guys
yea the whole thing wobbles.. i think its the actual sleve
i got one used off a guy.... it works and i have 20 miles on it.. it clatters like a normal clutch but just wobbles like no tomorrow.. wondering if thats normal for these.. also i have 1/2 spacers to fit the cover..
im wondering if i got a bum one.. i have a ht engine.. and the hat sleve buts up as far as it will go to the crank sleve but only till it hits the crank lip so it sticks out to far.. id have to machine it.. thanks for any help guys
yea the whole thing wobbles.. i think its the actual sleve
Last edited:
the sleve you put on covers the keyhole there is no cut in it like the stock manual gear.... it uses friction and the bolt... thats what mine is
