broke clutch shaft today solution? stronger machined shaft???

[uncleargenius1]

see attached for where it broke

my specs
20" freestyle bmx dave mirra bike strong as ****
my weight 140lbs wet
dax friction drive running titan 4 stroke 50cc
bmp friction drive kit
1.25 roller
riden 2 weeks daily at 50-100 miles per day trouble free until...

going about 35-40mph downhill on smooth pavement full throttle
got to the bottom of the hill stopped at red light
light turned green gave her gas high revs rpms and no go
hmmm so i look o no my clutch shafts broke

the standard ones steel but...

would a 6061 t-6 heat treated machine one be stronger?
if so there would be 2 benefits
1. less rotating mass weight better take off performance
2. the main reason stronger and not breaking like mine did

im sure no one makes one yet but if its stronger ill visit my machine shop
i dont want to unbolt the engine twice a month or get stranded far away
with no gas power

also if 6061 is to weak for this application maybe 7075 aluminium?
this ever happen to anyone? any ideas?


see pic attached

 

[cycledude]

Am assuming that you have the standard bmp roller with the bearing inside, I packed mine with lithium soap grease before I put it together just in case it was dry, I dont know if I used the right kind either just hoping.
I dont know if going up and down hill without pedal assist was also a problem, i gas up very little uphill and pedal as much as I can, use the breaks downhill.

Hope comment helps.

 

[uncleargenius1]

my bmp roller is the 1.25 with the one way locking bearing inside the roller still works and bearing are good the 1/2 shaft coming off the brass clutch plate just broke off where the clutch circle meets the shaft im thinking the shafts welded onto the clutch plate or its a forged mold

i was thinking maybe a solid machined aluminum clutch plate/shaft that starts off from the same block of aluminum could be stronger since its all same metal no welded pieces or at a minimum maybe a 3/4 shaft thicker bigger shaft providing more strength

the strange thing is it happened downhill and im a light rider 140lbs
this is sumthin id understand more if i was 250lbs full throttleing up
a steep hill then atleast theroticly it would make more sense
also my motors a 1.5-2hp titan and bmp list engines all they way up
to 4hp that can be used with there kit i like the kit and i dont see
any parts from it ever breaking in the future except the clutch shaft
i think i found this kits weak link hopefully bmp or some machinist maybe staton could build a stronger one and then maybe i can think about going over 2hp with the cyr420 2 stroke engine rated at 4hp or see if i can tweak my titan to 3hp with pipe/intake/jets

 

[5-7HEAVEN]

Did the shaft break where it connects to the clutch drum?

 

[uncleargenius1]

yup it broke on the outside of the clutch drum where it connects to the shaft

the outer diameter of the shaft is smooth with no breakage or strees showing but the inner diameter of the shaft is all stressed looking and appears where the breaking took place

 

[cycledude]

yup it broke on the outside of the clutch drum where it connects to the shaft

the outer diameter of the shaft is smooth with no breakage or strees showing but the inner diameter of the shaft is all stressed looking and appears where the breaking took place

Yeah, I was going to add a weld to that junction before putting the thing together, I didn't do it because I figured I didn't needed with my 35cc.
But I will do it if I put anything else together larger than a 35.

Anyway, thats 24 bucks with free shipping, how do you like that?
The solenoid on my bike just went out of business, its about 100 bucks, I dont like that>

 

[5-7HEAVEN]

I broke TWO Staton friction rollers right where they connect to the clutch drum. They snapped on my Mits TLE43 engine, just as I was reaching mid-to-high rpm range.

It was all my fault, because I did not install the rear support strut on the engine side. I was using a MODIFIED version of Staton's early-version single rear support strut. When I installed two rear support struts and made sure everything was solid, I stopped breaking friction rollers.

FWIW, the Staton friction rollers were installed on my BMP friction drive housing. I wanted to try 1.375" rollers and BMP didn't have spindles in that diameter.

 

[uncleargenius1]

i like that one person here who built a HF 79cc friction drive with a 2.75 aluminum wheel and no clutch bad thing though gotta hit kill switch when letting off gas alot or stoping and a 20lb engine on one side of the bike
as a temp fix i orderd a new clutch bell/shaft but longterm im looking to mount a hf 79cc on top of the bmp carrier and do a sprocket chain drive setup then ill just have to worry about snapping my chain

 

[uncleargenius1]

new bmp clutch drum drive shaft

Well I broke my second replacement clutch drum today this time not at the weld or driveshaft but the clutch drum itself. So I go to bmp to order my replacement. Wow the holy grail to friction drive a solid machined drum and driveshaft with no welds. I have been wanting this along time. I was so happy I bought 2. Even if it breaks in 6 months that's ok by me. It beats my current rate of 1 per month. I can deal with disassembly 2 times a year. Also I noticed there 1.5 roller looks to be a diff color perhaps harder compound? I know the green one lasted a few miles. I might test the red one. Or even better a 1.5 steel freewheel roller for long lasting for a lighter rider like myself seeking top mph. Will you make a steel 1.5 with freewheel one way lock bearings Please bmp? I will buy 2

 

[5-7HEAVEN]

BMP is not making the rollers. He's outsourcing them from other vendors.

These rollers aren't specifically manufactured as friction rollers for bicycle tires.

This MIGHT be where BMP'S spindles are coming from:

http://www.fairlaneproducts.com/OrderPage.asp?partNo=DR-502-95UR-EX625&padNo=

FWIW, methinks you have the same problem I did when I was breaking Staton friction rollers at the clutch drum.