Sprocket Gearing

[79josh81]

Hi josh,
arctic's right, the single key most likely won't cut it.
Try welding the sprockets together back to back and a big ol' Vee+fillet weld on the outboard end to join the sprocket pair to the shaft.
Sure you gotta renew the complete sprockets+shaft unit when the sprocket teeth wear out but that's 10,000 miles down the road, eh?

Yeah I was just going to say I suppose I could always weld the sprockets to the shaft after I get the distances set to take the stress off of the keys. I’m still not entirely convinced though yet that a 1/4” x 1/4” key would shear under the torque of the 650 engine.

 

[arcticXS]

Yeah I was just going to say I suppose I could always weld the sprockets to the shaft after I get the distances set to take the stress off of the keys. I’m still not entirely convinced though yet that a 1/4” x 1/4” key would shear under the torque of the 650 engine.

Again, look at the splines on the countershaft and its sprockets. At least 6 splines, each as solid as your key...... and the shaft and sprocket are most likely from a higher grade steel than those industrial type sprockets, and hardened as well.

 

[79josh81]

Again, look at the splines on the countershaft and its sprockets. At least 6 splines, each as solid as your key...... and the shaft and sprocket are most likely from a higher grade steel than those industrial type sprockets, and hardened as well.

Yeah I hear you. I’m not denying that a splined shaft and sprocket wouldn’t be a more stout setup, I’m just interested in the actual numbers of the set up I plan to run and whether the torque of the 650 engine would actually be enough torque to shear the key. Just because one way is better doesn’t mean another one won’t be sufficient. It’d be nice if there was someone on here who could run the equations with what I have just to see. Everything I’m finding online is saying it should handle the torque, but I don’t do this for a living either and I value the opinions of you guys as well.

 

[79josh81]

My mechanical engineering equation for this is:

Run it + drop the clutch in 1st gear = C or S

C = Cruising down the road
S = Shit blew up in your face

 

[650Skull]

Well if that’s the case then that sucks because I already have those sprockets and a shaft to match because you’re the only person that’s said something like that after 4 weeks of discussing that set up on here and other places online.

Go easy, its only 9 days since this thread was started. If you want instant engineering advice go to an engineering shop...........

Get a old gearbox shaft and mount that using the splines for the 17 tooth sprocket and get a plate made up with a spline mounting hole with bolts to attach the rear 33 tooth, (or whatever size your using), sprocket........Use spacers or the rear sprocket plate to make up the difference for the offset.

The gear shaft can be bearing mounted, as it is in the gear box, attached to your frame inside a purpose built cover........Yours to design.

I see some potential problems with this idea but they can be surmounted with a bit of thought.............

 

[TwoManyXS1Bs]

Josh, it's not just the torque, it's the vibrating oscillating gyrations. Even the grub screws will loosen up...

 

[79josh81]

Well since I already have the parts, I guess I’m welding the sprockets to the shaft in addition to the keys then like Fred said.

 

[79josh81]

FYI too....I did try to look for splined shafts and sprockets and other options as far as shafting and sprockets but there isn’t a whole lot out there like you’d think there would be without having to pay someone for custom machining at some point to make it all work. Trying to match shaft types, sprocket types with the tooth sizes I needed, and bearing sizes was a pain in the ass to say the least. I bet I spent 40 hours of my life looking for venders online, researching parts and their capabilities, and trying to match all of the parts that would work together and I always seemed to have one component that I couldn’t find that would work with the rest of the set up. Even finding something as basic as a pillow block bearing with a concentric locking mechanism and an rpm and load rating of what I needed was a bitch.

 

[TwoManyXS1Bs]

It *is* a tease, isn't it. We see guys doing/making stuff, get excited, make plans. Then realize that a 6-ton 14-inch lathe is needed, or a garage-sized baking oven.

I've seen some pillow-block bearings on Graingers...

 

[79josh81]

It *is* a tease, isn't it. We see guys doing/making stuff, get excited, make plans. Then realize that a 6-ton 14-inch lathe is needed, or a garage-sized baking oven.

I've seen some pillow-block bearings on Graingers...

Ain’t that the truth. Oh and I spent time on Grainger and probably 20 other industrial supply websites. Not too mention my searches also landed me on bearing supplier sites, farm equipment sites, steel supplier sites, and go kart equipment sites of all other things.

 

[arcticXS]

Well since I already have the parts, I guess I’m welding the sprockets to the shaft in addition to the keys then like Fred said.

Weld the sprockets to each other, either directly, or by inserting a machined spacer between them. Do not weld to the shaft. That way you avoid distorting the shaft, and introducing stresses into the shaft, that may induce shaft failure later.

 

[79josh81]

Weld the sprockets to each other, either directly, or by inserting a machined spacer between them. Do not weld to the shaft. That way you avoid distorting the shaft, and introducing stresses into the shaft, that may induce shaft failure later.

Yeah you’re right. I was thinking there would still be stress on the keys if I did that but I just realized that all of the stress would be on the welds and the keys would just be there to spin the shaft. Good catch.

 

[fredintoon]

Hi josh,
see post #20.
Weld the sprocket pair only to the outer end of the shaft.
That will allow the weld heat to mostly be absorbed by the sprocket pair so it'll not affect the shaft except at the weld zone.

 

[79josh81]

We’ll see what happens. I have a feeling doing this different ways is going to depend on a lot of variables that I’m not going to know until I get the jackshaft mocked up on the bike with the chains in place.

 

[650Skull]

I don't like the idea of welding in this area.....To much can go wrong.......Splines are used for a purpose

 

[79josh81]

Well the main reason splines are used is to make the sprocket removeable and make it solid on the shaft as if it were welded or machined as part of the shaft I'd think. Splines would be ideal, however I can't find what I'd need. Welding a shaft or welding a sprocket shouldn't be an issue if you don't slam too much heat into it and you don't quench it to cool it. I mean they sell hubs and sprockets separately that need to be welded together.

 

[650Skull]

Not so much as to much heat but how the heat is distributed to stop it from condensing and causing it to warp/move.

A small bit of undercut or porosity is also a concern.

I know your not advocating it, but just mentioning cooling a weld with water make me wonder your expertise regarding welding.......... Are you intending to do the welding your self?

Not saying not to weld but, i, as in me, woldn't feel 100% welding sprockets together with the stresses from acceleration and deceleration, chain snap and especially with the XS650 having no rear wheel sprocket dampers..........Its a design fault common on these bikes that manifests into clutch hub springs breaking ..........

 

[79josh81]

I’m just saying that as long as you don’t quench steel, the heat from the welding isn’t going to change the steel on the moleculer level to the point that it’s going to make it hard and brittle like some people think. I would never cool a weld with water and never have. I was just stating that because I didn’t know if you were trying to say welding in that area would be bad because the heat would weaken the steel somehow. The warping is the only real issue and as long as you take your time and don’t pound the sprocket with heat for too long it shouldn’t warp.

 

[650Skull]

I heard you and responded that i heard you on the water so that wasn't the issue..............my post bought up 4 or 5 different points and a question..........doesn't seem any of those were observed or responded to............

just my opinion and take on welding in that area...........

 

[79josh81]

You were questioning my "expertise" on welding because of the water/quenching comment I made so was assuring you that, while I do perform my own welding, that the quenching/water comment was less about the welding part and more an example about steel not weakening when heated from welding. Your other points and opinions on the subject were all taken into account for the decisions I'm going to be making about how to do this so thanks for the insight. You and others are right though, and I absolutely agree, that a splined shaft set up would be optimal. Unfortunately, from what I was able to find as far as parts online, I wouldn't be able to do it unless I had someone either machine the splined sprockets I'd need or machine a shaft that would work with sprockets I can find.