Jackshaft disc brake??

GoldenMotor.com

ocho ninja

Member
Jan 14, 2012
564
2
16
San Jose, CA
I heard the jack shaft disk brakes can be touchy aka have a hard bite

i seen some de tune the caliper or even cutting up an existing rotor to a smaller diameter helps
 

runnermike

Member
Nov 18, 2012
936
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16
Sanford, FL
Question......Should I have the front brake and the jackshaft brake isolated? Or, a better question, can I have both brakes on a dual lever? I'm only asking because one less brake lever is one less thing cluttering up my bars.....
 

maniac57

Old, Fat, and still faster than you
Oct 8, 2011
4,484
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memphis Tn
My understanding is the jackshaft mounted brakes are MUCH stronger due to the gearing advantage so it might be difficult to balance them on a single lever.
But I really have no idea. Just a guess.
 

greaser_monkey_87

New Member
Mar 30, 2014
397
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USA
I am considering a j-brake as well (shorthand for jackshaft brake). The one part I am lost on is where/how is a good way to mount the caliper.
 

greaser_monkey_87

New Member
Mar 30, 2014
397
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0
USA
Please forgive my ignorance, but I can't wrap my mind around how a brake on the jackshaft can stop the wheels from turning, and brake the bike. HELP! and where can I get that engine & jackshaft mount!?
The chain is connected to the jackshaft and the rear wheel. Stop the jackshaft from turning, stop the chain. Stop the chain, stop the rear wheel.
 

Ooontzler

New Member
Feb 24, 2014
57
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Bay Area, CA
The chain is connected to the jackshaft and the rear wheel. Stop the jackshaft from turning, stop the chain. Stop the chain, stop the rear wheel.
I guess I'm still missing something - how is this superior? To me it seems that a jackshaft brake simply moves the braking action further from the wheel, which is the thing we want to stop originally. Is it to do with the torque? Is it just bonus style points to have a disc brake on the jackshaft?
 

greaser_monkey_87

New Member
Mar 30, 2014
397
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USA
A brake works the same as a gear. The larger the gear, the more force is applied. The larger the brake, the more braking force. Gears affect each other in relation, i.e changing one gear affects how much force other gears in a series can apply. The same is true of brakes. A brake can apply more force to a smaller wheel or, in this case, the jackshaft. The jackshaft being smaller than the wheel allows the disc brake to apply far more braking force than it could if attached to the wheel.
 

runnermike

Member
Nov 18, 2012
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Sanford, FL
It is just an extra brake. It is not taking the place of the other brakes. It will slow the engine, thereby slowing the clutch and disengaging it quicker. And yes, it looks cool and is really not hard to do, especially when you have the parts laying around....
 

greaser_monkey_87

New Member
Mar 30, 2014
397
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USA
My understanding is that having the disc brake on the jackshaft allows it to have much more braking power. Therefore, I plan on having a motorcycle drum in front, which I believe will allow more than adequate braking power for normal stops at the speeds I like to cruise, and the jackshaft disc brake for emergency stops only.
 

scotto-

Custom 4-Stroke Bike Builder
Jun 3, 2010
6,505
25
38
Ridin' inSane Diego, CA.
Please forgive my ignorance, but I can't wrap my mind around how a brake on the jackshaft can stop the wheels from turning, and brake the bike. HELP! and where can I get that engine & jackshaft mount!?
In a nutshell......the rear wheel (sprocket) is driven directly by a chain from the jack shaft. You stop the shaft from turning, the rear wheel also stops turning which is braking to the rear wheel.

On my 212cc bike, the engine itself does most of the rear braking with it's compression when you let off the throttle. The jack shaft brake is just there if I need just a little more braking power in certain situations while racing.

The front brake of course is used for most of your stopping power as far as all vehicles are concerned.

Here are a few more shots of the j-shaft brake on my 212cc bike.....





 

Dulcijo

New Member
Aug 25, 2014
29
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North Carolina
My jackshaft brake is very sensitive and it would work great but I have a spring loaded chain tensioner and it puts great stress on the chain tensioner.