Help - Crank Clearance Problem

59Cruiser · Aug 15, 2011

I'm hitting snags on just about every part of my build but so far have been able to overcome them. Well, my discovery today is major and may just put a stop to my hole build. Please help ... I'm building an old schwinn 60's era bike. Everything on this dang thing is just non-standard it seems.

My big issue #1 for today is that the cranks don't clear the motor! I need about another 1/4" at least between my cranks so they clear the engine.

So ok, can I somehow bend these things out a little bit without screwing them up? Anyone else had to do this? I was thinking about taking them off, putting them in a vice and using a pipe to slightly bend each side out what do you think?

And issue #2 is that the motor does not clear the chain guard. I can't get the motor low enough to mount the frame because the chainguard is in the way. So no big deal except that my chainguard is amazingly beautiful! I don;t want to do without it. Its nice shiny chrome schwinn chainguard and I really like it. So I will try to figure this one out too but first the dang cranks?

Any suggestions very very appreciated!

wayne z · Aug 15, 2011

Tell us what kind of motor u got.
You can buy wider cranks for 29 bux, or like I did, use a acetylene torch and mildly heat them close to the base and slip a cheater pipe on it and bend them out equaly some, then heat them about an inch fron the pedal holes, and bend the other way until they are parallel to the crank sprocket.
If you don't use excessive heat, and run water on thr BB right afrerward, you can do it while still assembled on the bike, and the chrome will polish out pretty good.

Almost everybody has to adapt their front mount.

It's important to snug the rear mount first, to the seat tube, at whatever height that gives you chainguard clearence.
Then adapt the front mount .There's various kits sold for that, and most motor kits come with adaptor hardware. Lotta ppl use their imagination and whatever is on hand to build the front mount, muffler clamps, u-bolts, ect.

Best to not use the mount that requires drilling the frame.

If this is a HT 2 stroke kit, you better pull all the covers and check the tightness of every fastner you can find.

Also check the entire induction and exhaust system for restrictons from weld slag and improper cut gaskets. These are not plug and play engines.

I have built 7 of these and every one had loose screws on the mag coil and most other areas.

Venice Motor Bikes · Aug 15, 2011

You can either heat the crank with a torch & bend it, or buy a modern one (that's wider) for $10.

59Cruiser · Aug 15, 2011

Well, I must say I jumped the gun on this post. Sorry about that, I'm a noob and I actually thought this thing would simply bolt on and I would be motoring down the road. Thanks for your suggestions and for not giving me the reminder I deserve to actually read or search the forums first.

So anyway, the motor is one of those 49cc chinese deals from eBay listed as 80cc. I think I am going to go ahead and buy a new crank since the sprocket on my old schwinn crank is a bit bent anyway. hopefully I won't have any issues with getting a modern one that fits the bb.

As far as the motor mount, after I posted this I searched around these forums ... shame on me should of done that first. I am leaning towards a simple "L" bracket with a muffler clamp turned on its side. Personally, I think simple is good and mainly this setup offers all kinds of adjustment.

Funny thing is, I work for a huge OEM and we have custom brackets all over the shop. These things are usually made out of 1/4" steel and heat treated

I'm sure we have a few scraps. I am going to see if I can find something that will fit ... simply just need one thats about 4" long and about 2 1/4" wide. I'll drill it at time of mount to get it at the optimized position.

I'm also going to paint it to match my bikes new paint job so it will look good too. So, yeah, uhm, I feel pretty silly right about now. Sorry about this post!

mapbike · Aug 15, 2011

Great info here fella's.........

(^)

, map

mapbike · Aug 16, 2011

The L bracket type mount works great.....

The engines that are claimed to be 80cc are actually 66cc.

The new cranks is a great idea, I would also consider using a 36T crank sprocket, I have this on one of my cruiser bikes and it sure makes it easier to peddle vs the standard 44T most of the single speed cruisers come with.

No need to be sorry about the post here, thats what this forum is all about, Q&A and none of them dumb ones, even though we may look back on some of them and think to ourselves........"what the heck was I thinking" I should have known that......!

These things just happen to those of us on here that are human, now those who aren't dont have this problem because they know it all..............it seems...LOL!

Glad your making head way on the build and best wishes, cant wait to see some pics when it's done.

Peace, map

59Cruiser said:
Well, I must say I jumped the gun on this post. Sorry about that, I'm a noob and I actually thought this thing would simply bolt on and I would be motoring down the road. Thanks for your suggestions and for not giving me the reminder I deserve to actually read or search the forums first.

So anyway, the motor is one of those 49cc chinese deals from eBay listed as 80cc. I think I am going to go ahead and buy a new crank since the sprocket on my old schwinn crank is a bit bent anyway. hopefully I won't have any issues with getting a modern one that fits the bb.

As far as the motor mount, after I posted this I searched around these forums ... shame on me should of done that first. I am leaning towards a simple "L" bracket with a muffler clamp turned on its side. Personally, I think simple is good and mainly this setup offers all kinds of adjustment.

Funny thing is, I work for a huge OEM and we have custom brackets all over the shop. These things are usually made out of 1/4" steel and heat treated
I'm sure we have a few scraps. I am going to see if I can find something that will fit ... simply just need one thats about 4" long and about 2 1/4" wide. I'll drill it at time of mount to get it at the optimized position.

I'm also going to paint it to match my bikes new paint job so it will look good too. So, yeah, uhm, I feel pretty silly right about now. Sorry about this post!

59Cruiser · Aug 16, 2011

Hopefully I can pick some up at one of my local bike shops that will work. I only have two bike shops near me and they don't seem to stock alot of the old school parts. I did a quick search online and not sure if I can find the right size and also a new sprocket. I was considering buying these but they are out of stock: Wide Crank Pedal Kit [4S-CDS-WCPK] - $29.99

I am going to take the original cranks to work with me tomorrow and see if I can put them in the pipe bender and flatten ou the sprocket. If all goes well, I will be coming home from work with a wider set of cranks and a front engine mount and will be continuing the build.

silverbear · Aug 16, 2011

Nice bike. Welcome to the forum. You have another option. I've built several of the Schwinns from the fifties and sixties.
With a bump start China Girl you can probably get away with just switching the one piece pedal crank with any one piece pedal crank from a newer oriental made bike as they are a little wider than the old Schwinns. I've done that and it works. It isn't going to give you enough if you have a pull start or automatic as they are wider.
You can also use two of the motor mounts up front with longer bolts (I use allthread and cut it to length ... can get that at a fastenall store). That raises the motor up enough and gives a good solid mount. The other options mentioned will work. I've cold bent Schwinn forks with a vice and water pipe as a cheater on the pedal arm. That will require two bends, one out further down on the arm and one back in again up at the pedal end so the pedal sits parallel with the ground. The only source I know of for one piece extra wide cranks is out of stock and will be for months. A three piece extra wide will require a bottom bracket adapter for more money yet.
The Schwinn is not a shoe in for a China Girl, but is worth the effort once you're done and if you do another you'll know how to do the next one easily. Good, solid bikes they are.
SB

mapbike · Aug 16, 2011

Heres a link to get you a good set of cranks at a great price and a sprocket.

I'd go with the 7" cranks so tiy will have better leverage to make peddling easier, on the sprocket page just scroll down and you will see the 36T sprockets.

you can get both pieces right here for $20 + shipping.

Bike Parts

Bike Parts

Peace, map

59Cruiser · Aug 16, 2011

Really good information here and suggestions ... very appreciated. I'm a little confused about the cranks though. Almost all sites I checked out only spec the crank arm length and say nothing about the width between them or the threads. Also I am a little worried about them fitting in my old schwinn BB.

I measured the width of the motor and it seems that I need at least 5 1/4" between my crank arms and that would be cutting it close. 5 1/2" would be ideal I think.

MapBike, thanks for the links ... do you happen to know how much clearance are between those crank arms? Also, is a 36T sprocket pretty much standard since I left mine at the shop and can't count them now. Also, those dang twisted chrome sets are way tempting. Is it just me or what but it seems that there are no threads on those cranks?

As a back-up, I brought my crank to work today and our pipe fitter is going to bend them up for me. He's going to heat them up and do it right. These guys do amazing things with some of the special machines we build so I am confident they will be great when hes done. Should be done tomorrow. Only thing is I'm not too happy about having shorter cranks and not sure how its going to look. You never know ... maybe be kind of cool cause they will be unique. But if they turn out ugly I'm ordering that 6" flat twist set

Also, I sketched up a bracket for the front mount and started working on it at the shop today. Its going to be awesome and will be done tomorrow. I'll post some pics when I can.

mapbike · Aug 16, 2011

The cranks on that site should work just fine, they will be the standard modern width most likely and will work if you decide to go that route I'm sure.

Yeah those twisted cranks are real nice looking.

normally the 44T is standard but the 36T just makes it easier to peddle the bike, thats why I like it myself.

Peace, map

59Cruiser said:
Really good information here and suggestions ... very appreciated. I'm a little confused about the cranks though. Almost all sites I checked out only spec the crank arm length and say nothing about the width between them or the threads. Also I am a little worried about them fitting in my old schwinn BB.

I measured the width of the motor and it seems that I need at least 5 1/4" between my crank arms and that would be cutting it close. 5 1/2" would be ideal I think.

MapBike, thanks for the links ... do you happen to know how much clearance are between those crank arms? Also, is a 36T sprocket pretty much standard since I left mine at the shop and can't count them now. Also, those dang twisted chrome sets are way tempting. Is it just me or what but it seems that there are no threads on those cranks?

As a back-up, I brought my crank to work today and our pipe fitter is going to bend them up for me. He's going to heat them up and do it right. These guys do amazing things with some of the special machines we build so I am confident they will be great when hes done. Should be done tomorrow. Only thing is I'm not too happy about having shorter cranks and not sure how its going to look. You never know ... maybe be kind of cool cause they will be unique. But if they turn out ugly I'm ordering that 6" flat twist set

Also, I sketched up a bracket for the front mount and started working on it at the shop today. Its going to be awesome and will be done tomorrow. I'll post some pics when I can.

59Cruiser · Aug 16, 2011

Thanks ... I'm gonna see how things go with the crank tomorrow but I am soooo tempted to order the 6" twisted. Why did you have to go and show me that site ... I'm afraid I'm going to drop a boat load of cash now that I see all that cool stuff!

mapbike · Aug 17, 2011

LOL!

I figured you might like that sight..........lots of goodies on there for sure......

The prices are pretty darn good also, for a couple 100 $bucks$ I fella can get a good bit of nice stuff to trick out a bike, I have plans for several things for my Huffy Karaoke, 26" Banana seat, tall sissy bar, ape hanger bars, springer forks, sissy bar pad, and maybe a couple other things.

Peace, map

59Cruiser said:
Thanks ... I'm gonna see how things go with the crank tomorrow but I am soooo tempted to order the 6" twisted. Why did you have to go and show me that site ... I'm afraid I'm going to drop a boat load of cash now that I see all that cool stuff!

The_Aleman · Aug 17, 2011

Make sure you get the handlebar dingleberries and the 100 spoke wheels too.

You in South Texas? Real far South?

lol

mapbike said:
LOL!

I figured you might like that sight..........lots of goodies on there for sure......

The prices are pretty darn good also, for a couple 100 $bucks$ I fella can get a good bit of nice stuff to trick out a bike, I have plans for several things for my Huffy Karaoke, 26" Banana seat, tall sissy bar, ape hanger bars, springer forks, sissy bar pad, and maybe a couple other things.

Peace, map

mapbike · Aug 17, 2011

Nope I'm a full Blooded Central Texas Country fella that lives on 150 acres about 10 miles from the nearest town, not a low rider type ,just looking to make one of them look that way for a conversation piece and just for the fun of it.

I'll have to stop just shy of the dingleberries, fuzzy dice, 100 spoke wheels, hydrolics and the curb feelers though...LOL!

Dont anyone get me wrong here, nothing against anything I mentioned above...!

Just not my personal taste thats all, I'm actually an old school country boy hot rodder, was in my youth a Dukes of hazzard type......, Country living, fishing, hunting, rough-in it camping, fast cars and pretty girls.......ect....!

The_Aleman said:
Make sure you get the handlebar dingleberries and the 100 spoke wheels too.

You in South Texas? Real far South? lol

59Cruiser · Aug 17, 2011

My cranks got put on hold today since I was just too swamped at the office today to deal with it. Should have my front motor mount and cranks done tomorrow though if all goes well. I do hope they work cause I like my old school schwinn pedals also. They are not 1/2" but I think 7/16" instead. I spent and hour or so cleaning them and they look pretty damn good on the bike and so does the stock sprocket. Its the signature schwinn sprocket that everyone recognizes.

I almost forgot about my coaster arm so I'm taking that in to bend also. I put the rear sprocket on today ... well kind of. It was a major pain in the a$$! All went well except one of the cheapo bolts that came in the kit has messed up threads in one spot. So need to replace that.

I don't think I'm going to be able to get the sprocket perfect like I want it without spending another few hours on it. It will have just a very slight side to side wobble and up down. I'm going to get it the best I can and see how it goes. I already spent 3 hours on it and its somewhat close. At least not wobbling all over the place.

Hoping I don't have to chop the rear fender for chain clearance but we'll see when I get the motor mounted. Wondering what you guys use for chopping down chrome fenders? I don't have much for tools here at home but was thinking a hack saw or my cheap chinese non UL listed angle grinder might do the job.

Oh yeah .... and kind of wierd .... I counted the sprocket teeth today and it has more then 44 ... not exactly sure but I counted twice and swear there is like 49 or something.

kevinkrg6 · Aug 17, 2011

59Cruiser said:
I'm hitting snags on just about every part of my build but so far have been able to overcome them. Well, my discovery today is major and may just put a stop to my hole build. Please help ... I'm building an old schwinn 60's era bike. Everything on this dang thing is just non-standard it seems.

My big issue #1 for today is that the cranks don't clear the motor! I need about another 1/4" at least between my cranks so they clear the engine.

So ok, can I somehow bend these things out a little bit without screwing them up? Anyone else had to do this? I was thinking about taking them off, putting them in a vice and using a pipe to slightly bend each side out what do you think?

And issue #2 is that the motor does not clear the chain guard. I can't get the motor low enough to mount the frame because the chainguard is in the way. So no big deal except that my chainguard is amazingly beautiful! I don;t want to do without it. Its nice shiny chrome schwinn chainguard and I really like it. So I will try to figure this one out too but first the dang cranks?

Any suggestions very very appreciated!

1. You can try and bend them, but they may just break.

Wide Cranks - Wide Crank Pedal Kit

2. I had to take off my beautiful schwinn chain guard as well. It sucks. But it looks good now with both chains anyway.

DON'T try and mount your motor higher just for the chain guard. I tried this by lengthening the studs, and this is a bad idea. It causes problems, and it's not safe.

kevinkrg6 · Aug 17, 2011

59Cruiser said:
Hoping I don't have to chop the rear fender for chain clearance but we'll see when I get the motor mounted.

I had to. Just sayin.

Don't use a hacksaw. That will screw it up. Draw the cuts with a sharpie and cut with a dremel and discs. It may take up to 10 discs but it will work. You can see where I cut for clearance. Then sand it. I used 60 grit then 400 to give it a nicer finish. You can go 600 grit after that if it bothers you.

59Cruiser · Aug 21, 2011

Kevinkrg6,

Thanks for the link .... I might go ahead and buy a crank and sprocket. That wide crank set looks nice and wide and I like that it comes with everything so I know I won't have any issues with it fitting.

However, I am very tempted to get this Flat twisted crank with this Sprocket . The price difference after shipping is only about 5 bucks.
Does anyone have any feedback on these or suggestions on the 6" flat twisted crank with that sprocket. I am worried it won't be wide enough or maybe won't fit my BB and existing hardware?

Also, I am thinking about another mounting idea. It would just look cleaner. It involves extending the back mount so that the front mount is direct to the frame. I would do this by using extra long studs with a shim and stansions (if thats what you call them) on the back mount. I think it would be strong but worried about the studs being that long. I would use hardened steel of course. This mount would move my chain forward making it about 3" longer which should be ok I guess. Anyone done something like that before for a mount?

Thanks for all the suggestions and help!

mapbike · Aug 21, 2011

59Cruiser

I don't suggest extending the engine forward with longer studs at back, best and strongest set up is the mount the rear of the engine directly to the seat post down tube and then make an extended mount to secure the front of the engine to frame, the rear studs on these engines are the most prone to cause you grief because they take the bulk of the stress, been down that road myself.

Now I use grade 5 6mm studs on mine that I make out of 6mm x 100mm bolts I get at my local industrial fastener supply store, I use blue loctite on all mounting fasteners and nyloc lock nuts with flat & lock washers.

Those flat twisted cranks should work just fine if you like them, they should be the same dimensions as the standard width cranks used today, all other hardware should also work fine, that stuff is pretty universal on the one piece cranks in my experience.

Best wishes on the build, its gonna be a nice one when you're done.

Peace, map

59Cruiser said:
Kevinkrg6,

Thanks for the link .... I might go ahead and buy a crank and sprocket. That wide crank set looks nice and wide and I like that it comes with everything so I know I won't have any issues with it fitting.

However, I am very tempted to get this Flat twisted crank with this Sprocket . The price difference after shipping is only about 5 bucks.
Does anyone have any feedback on these or suggestions on the 6" flat twisted crank with that sprocket. I am worried it won't be wide enough or maybe won't fit my BB and existing hardware?

Also, I am thinking about another mounting idea. It would just look cleaner. It involves extending the back mount so that the front mount is direct to the frame. I would do this by using extra long studs with a shim and stansions (if thats what you call them) on the back mount. I think it would be strong but worried about the studs being that long. I would use hardened steel of course. This mount would move my chain forward making it about 3" longer which should be ok I guess. Anyone done something like that before for a mount?

Thanks for all the suggestions and help!

Help - Crank Clearance Problem

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