Unchain my bike... or so I thought...

Status
Not open for further replies.
BusyLittleShop

BusyLittleShop

Joined
Dec 9, 2011
Messages
2,202
Location
Ca USA
Unchain my bike... or so I thought...

Hans Renold is credited with inventing roller chain in 1880... but
here we are 127 years later and bikes are still laboring under a
steely... heavy... clanky... messy... chain... Mercy me chains are a
pain... belts spell relief... and so my belt drive conversion starts
with an engineering drawing...

gallery_3131_51_26197.jpg


Gates Poly Chain comes in 3 belt sizes... 14mm pitch is what HD
employs on their cruisers... 8mm is what I used on the VF500
Belt-0-Ceptor... 11mm is the little known in between belt but only
comes in lengths of 155T and 172T... I need 166T to make it work on
Mr.RC45...

gallery_3131_51_3294.jpg


I started with a Buell 11mm pitch sprockets and belt... a 30T up
front and 70T out back... they were machined them to fit Mr.RC45...
so far so good



Buell's steel 30T 11mm spocket installed on the RC45 primary shaft...

gallery_3131_51_45790.jpg


Buell's aluminum 72T 11mm sprocket installed on the RC45 axle...

gallery_3131_51_18651.jpg



Ideally I needed 628mm between centers as evident with Mr.RC45's 17T
43T 110 links of chain prove to show...

gallery_3131_51_100085.jpg


But when I added the Buell 30T 72T 155T setup it measured 561mm
between centers... 67mm too short...

gallery_3131_51_84588.jpg



Next I ordered a 172 tooth belt from BMW but with the Buell sprockets
the BMW belt was 664mm between centers... 36mm too long...

gallery_3131_51_60739.jpg




Maybe if I machine my own 76T sprocket so I started with a 20lb block
of 7075 T6 Aluminum...

gallery_3131_51_62149.jpg



After the teeth were cut by RCD Engineering the block was down to 10
lbs at this stage...

gallery_3131_51_496.jpg



After milling the spokes using only hand eye coordination it was down
to 1 lb 13 oz...

gallery_3131_51_52808.jpg



Now with the Buell 30T sprocket 172T BMW belt and 76T home made
sprocket the distance between centers was 651mm... 23mm too long...
because of the single sided swing arm I limited to 20mm adjustment so
I knew it would be close... how close??? less than 3mm or .118
thousands of an inch separates success from failure...

gallery_3131_51_80322.jpg



I have failed to unchain Mr.RC45... not that I didn't come close... I
came within 3mm of enjoying a light weight... maintenance free...
snatch free... lubeless belt drive system... it all came down to
finding the right number of teeth in a 11mm pitch belt... and so with
only 2 bikes in the world that employ the 11mm pitch belt (2003 Buell
and the 2007 BMW 800) I have to wait for a 3rd bike to employ the
little known 11mm pitch Poly Chain Belt...

So in conclusion after $1000 dollars in parts and a custom 7075 T6
aluminum sprocket consuming over 30 days worth of machining... I have
NO joy to report... in fact I'm devastated and sad... not to mention
Gates Rubber wants $65K for the mold of a custom 166T 11mm pitch
belt...

Mock up
gallery_3131_51_84342.jpg
 
Dumb question. Couldn't you come up with a spring loaded idler like the ones used on serpentine belts to take up the last bit of slack?
 
Doesn't the Buel use a belt tensioner? Would you be able to take some slack out of the belt with a tensioner? I'm not sure after it's all said and done, if you added a tensioner it would gain back any weight you've already lost. Just a thought.,,
 
Beautiful machining, but holy snapping duck [censored] why didn't you do the 15 minutes of maths that would have proven it either worked or didn't before blowing that time/cash?
 
Originally Posted By: Brad_C
Beautiful machining, but holy snapping duck [censored] why didn't you do the 15 minutes of maths that would have proven it either worked or didn't before blowing that time/cash?


Agreed on both parts.
 
+1 on the idler pulley, it would be on the bottom of the swing arm so the weight would be low at least.

Just do it, you are THAT CLOSE, just get'r dun... Sweet bike!
 
My grandfather's Millwright's Manual has the equations that would have given you the required belt length and illuminated your folly for a great deal less money.
 
Holy $10,000 gold-plated toilet seats, Larry. If you had made a real engineering drawing you would have had your nominal center to center distance before you ever touched carbide to billet. I guess that's machining chips under the mill now.

Idler is one way to it, since you've got no reverse, but you could also make the 172 tooth/11mm pitch belt work if you increased the number of teeth on a new driven sprocket - not so sure I'd have faith in you to hob or EDM the spline on a +1 tooth counter sprocket though in order to maintain that original gear ratio. But I'd part with 10 or 15 mph of top speed on that race bike for a lil more acceleration - specially if I was plannin on runnin it on public roads.
 
Originally Posted By: faltic
Dumb question. Couldn't you come up with a spring loaded idler like the ones used on serpentine belts to take up the last bit of slack?


I already thought about a idler roller but the BMW belt is
kind of rubbery whereas the Buell belt is more plastic... the
different being you can run a roller against Buell belt but not
against the BMW belt without taking the life out of it... besides I
don't have the room on Mr.RC45 dense packaging because the idler
would have to be the same diameter as the front sprocket...
 
Originally Posted By: Brad_C
Beautiful machining, but holy snapping duck [censored] why didn't you do the 15 minutes of maths that would have proven it either worked or didn't before blowing that time/cash?


Thank you... I did do the math but I just had to make the chips fly you understand...
 
Originally Posted By: CT8
Does the 7075 have to be heat treated after machining?


7075 T6 sports sufficient strength to support a belt drive sprocket without heat treating
however I have plans to Hard Anodize the surface in the interest of longevity...
 
Originally Posted By: hpb
Awesome. Don't quit now!


Thanks... I never quit... this is my second belt drive conversion... my first was
my 84 VF500 Interceptor... you see back in 86 I was at Daytona 200 and
managed a meeting with HRC Engineers on the possibility for
converting my VF500F Interceptor from chain to a 8mm belt... they
stated to me that it was *impossible* to add a belt drive *their* bike
because I would need to start with a belt and design the whole bike
around it... I thought OK I got my answer from the experts but I
wasn't happy about abandoning my dream... I'm the type who can not
stop thinking about solving a problem... I had to solved it and I
did... when I show cased my engineering and machining work to the same
engineers they nodded affirmative and ask what was I going to do next
to my bike??? maybe build my own aluminum frame I shot back... this
time they replied that I was probably the one who could to that as
well as the conversion...




86 VF500F Belt-0-Ceptor... I racked up 98,000 trouble free miles...
BeltCloseUp.jpg

gallery_3131_51_14630.jpg
 
Status
Not open for further replies.

Similar threads

turboseize
Needed something reliable, so I sold the Saab and bought an Alfa
2
Replies
31
Views
3K
Popsy
F
  • Locked
What oil should I use for my Subaru Impreza?
Replies
7
Views
2K
NGRhodes
M
  • Locked
AutoRX....? I don't think so.
Replies
13
Views
4K
badtlc
BusyLittleShop
  • Locked
I turn 65... so I'm reminiscing the milestones...
Replies
16
Views
16K
sunruh
S
  • Locked
My Old Bike and Getting in Shape
2
Replies
21
Views
9K
sleddriver
Back
Top