Kubota Diesel Motorcycle

[Lil Foot]

I'm wondering if a tapered bolt like the one in the last picture would work?

Clean & elegant solution, my only concern is that you will not be able to torque them to the same high levels as other style bolts.
Beautiful machine work.

 

[coachgeo]

Yeah Tapered would be best when it comes to keep width of bike reasonable. Would having the outboard bearing providing extra support reduce need to be torqued as much as those deeper in the Lil Foot referenced?

 

[JeffL]

Couple of thoughts:
-Socket head bolts are not usually used with washers. If you do use them make sure the washer matches the bolt grade. A soft washer will fail.
-Can you counter bore the bolt holes sinking the head of the bolt into the flange.
-Flat head machine screws are not usually used in dynamic assemblies. #2 above is the preferred method. The loading on the bolt head is different as each taper is trying to center. If all hole locations were perfect, micron or less, then no side loading would occur.

Just thinking out loud. Jeff

 

[Yooper]

The more I think about it, the less I like the idea. Some good points were brought up like torquing and bolts wanting to center. My fear is that with these bolts, one or two could be taking more stress than the others. The taper then increases the leverage on the bolt head which could lead to failure. Then it's on the next bolt and so on, leading to a chain reaction. Not a good scenario.

I could counterbore the holes. Right now the flange is at a half inch thick. Question is, how deep can I go?

 

[coachgeo]

What is clutch edge clearance to next set of holes more outboard on the flywheel. Just wondering if wider base alleviates this issue?

There is/was? some remains of fins on the backside of the clutch/Pulley. These fins were there to help reduce heat which can cause belt wear and slip. If their remains are still on backside maybe only the fins that will conflict with bolt heads could be clearanced??

not sure if possible but having a few channels in the thing to move air toward clutch won't bother me any

 

[BadDog]

Why not get regular or low hex-heads, and counter sink those? As long as there is some chamfer in the bore to prevent stress risers, I would think it should be ok to bore leaving only 1/4" or so. And there are many other fastener options. Button heads come to mind. Shallow bore and you again have at or near zero above the surface. Torque is again limited, but you eliminate the taper issues. Are the bolts the sole locating structure, or can you add a pin to handle locations and load. Bolts are best if used only to clamp, pins (keys, etc) should be providing solid location across the shear.

But confidence? Can't offer much.

That's why I tend to severely over build everything. It takes a good deal of knowledge AND a good (expensive) software packaged to do a full (and accurate) FEA. And I hate to think about building stuff only to have it fail, so over build I do...

 

[coachgeo]

.... Are the bolts the sole locating structure, or can you add a pin to handle locations and load. ......

Wondered about that too.

NI...Wolfman is the flywheel balanced to the engine on the D722? Do you have any recommendations moving forward?

 

[Yooper]

What is clutch edge clearance to next set of holes more outboard on the flywheel. Just wondering if wider base alleviates this issue?

There is/was? some remains of fins on the backside of the clutch/Pulley. These fins were there to help reduce heat which can cause belt wear and slip. If their remains are still on backside maybe only the fins that will conflict with bolt heads could be clearanced??

not sure if possible but having a few channels in the thing to move air toward clutch won't bother me any

Curtis machined most of the fins down. I wouldn't go any further.

 

[Yooper]

Why not get regular or low hex-heads, and counter sink those? As long as there is some chamfer in the bore to prevent stress risers, I would think it should be ok to bore leaving only 1/4" or so. And there are many other fastener options. Button heads come to mind. Shallow bore and you again have at or near zero above the surface. Torque is again limited, but you eliminate the taper issues. Are the bolts the sole locating structure, or can you add a pin to handle locations and load. Bolts are best if used only to clamp, pins (keys, etc) should be providing solid location across the shear.

But confidence? Can't offer much.

That's why I tend to severely over build everything. It takes a good deal of knowledge AND a good (expensive) software packaged to do a full (and accurate) FEA. And I hate to think about building stuff only to have it fail, so over build I do...

I used to be a diesel mechanic in a former life. To the best of my memory(uhh), the flywheels on the Cummins engines were just located by the bolts. I do have some dowel pins in my collection along with the reamers. As I'm sitting here typing this, I'm liking your idea! This is why I post my builds. More eyes on it, the better.

 

[Yooper]

Wondered about that too.

NI...Wolfman is the flywheel balanced to the engine on the D722? Do you have any recommendations moving forward?

Coach, I think I can answer this and have NIW back it up. The bolt holes on the flywheel are not evenly spaced on the bolt circle, which would mean it can only go on one way. Three of the five holes are evenly spaced, and then two are off. When I made the replica of the crankshaft, (see my next post) I used 3/8" bolts which just allowed enough slop so all the bolts would go in. I can only assume this is because it is balanced to the crank.

 

[Yooper]

Making the replica of the crankshaft, then mounting it in the lathe and torquing up the flywheel. Checked run out, which is at .0015". On to the next step.

 

[Yooper]

Mounted the stub shaft and torqued this to the flywheel. Checked run out, and then cut enough of the shaft off so I can establish a new center that will be concentric with the flywheel. Brought in the live center and here it will sit for a day and relax. Will check all the run outs prior to final machining.

As far as the bolts go, if I were to install two dowel pins 180* apart, does this bring our tapered bolts back into play? I could also counterbore the bolt holes 5.3 mm (approx .208" deep) to allow for regular capscrews. Any engineers reading this? Otherwise, I have a good friend that is an engineer that can crunch the numbers. I'm using 1045 steel.

 

[Yooper]

What is clutch edge clearance to next set of holes more outboard on the flywheel. Just wondering if wider base alleviates this issue?

Coach, this would solve the whole issue. Unfortunately, the material I had on hand was not big enough in diameter to go there.

 

[North Idaho Wolfman]

Stove bolts would work, I've seen quite a few on flywheel assemblies, but like others have said, bolts set 1/4" in the plate with no washers would work better, and yes adding 3 dowel pins would insure no stress and no mis-balance.

The flywheel is balanced and does effect engine balance, and it does only fit on the crank one way as to keep balance.

I wouldn't have gone any wider on the mount plate, it's just more mass for the engine to have to turn.

 

[JeffL]

Normal bolts should never be used for alignment of rotation/dynamic assemblies. Many flywheels are centered with a boss or recess that mates with the crank. Dowel pins are probably best as they remove all play from the assembly during assembly.
Counter bore the flange and assemble without washers.

 

[Yooper]

More progress on the stub shaft. Finished up the lathe work after rechecking all the run outs. Polished the output shaft to 1.000" and then slid the clutch on to check fit. The Mitutoyo didn't lie to me (it never does), slid on perfect. Last was to drill and tap the output shaft to receive the retainer bolt.

 

[Yooper]

Back at the mill to counterbore the bolt holes and to drill and ream the dowel pins. I decided on five pins vs three because there would be no interference with the bolt holes and it just plain looks pretty! Countersunk the back of the clutch bore until the clutch would bottom out on the stub shaft face.

Next up will be the retainer bolt. Going to have to wait a day or so because the weather man is calling for some good stump grinding weather.

 

[coachgeo]

..... Going to have to wait a day or so because the weather man is calling for some good stump grinding weather.

There is a time to build.. and a time to destroy

Looks great.

 

[Lil Foot]

Very nice. Out of curiosity, what lathe do you have?

 

[JeffL]

Yooper, that is fine work! I really like the five dowels. Makes me think of the time I popped all the heads off the flywheel bolts of a race engine (over rev) and the dowels held everything in place long enough to shut down. Flywheel and crank were toast but, I walked away.
With this design the bolts provide load/friction between the flange and flywheel that will transfer torque and the dowels will also lock the flange and flywheel together providing a redundant system. Again great work! Jeff