Grib are selling kits to move the front brake arm from facing rear to facing forward on the Grimeca brake as used on the Fantic 200.

Has anyone done this? If they use the same brake cam, and the arm is the same length, what is the advantage of rotating the cam anti clockwise instead of clockwise?

Regards,

Peter.

On swm's it is a pretty standard mod, gives a better cable run and stops the outer sawing through the yokes.

I don´t know about the configuration at SWM but it might has something to do with brake servo effect from wheel rotation? Servo effect in one direction, opposite the other way round (drum brakes only)

Come on @nzpeterb you asked the same question on facebook, are you going to get involved in the debate you chose to start ?

b40rt,

Not sure what debate you want. 

My question was a request to be enlightened on the advantages (if any) of changing the front brake lever from rear facing to front facing.

Your response suggested it worked better on SWM as it improved the cable run. I don't think this is relevant for the Fantic 200 as the cable run is already good.

The other response  talked about the effect of actuating the brake based on the direction of wheel rotation. The brakes are conventional drum with one leading and one trailing shoe, so the wheel rotation will not have any impact.

By comparison a twin leading shoe brake is designed only for the wheel rotating in one direction, but this is not what the Fantic has. 

The only advantage I have identified to moving the arm to face forward is to overcome a worn brake cam. Changing the direction of cam rotation will use a different face on the cam.

If the drum is true and the linings are good (soft for trials) then the next steps to improve brakes are a longer brake arm, or changing handlebars levers to ones with a different fulcrum distance.

Regards,

Peter.

 

3 minutes ago, nzpeterb said:

b40rt,

Not sure what debate you want. 

My question was a request to be enlightened on the advantages (if any) of changing the front brake lever from rear facing to front facing.

Your response suggested it worked better on SWM as it improved the cable run. I don't think this is relevant for the Fantic 200 as the cable run is already good.

The other response  talked about the effect of actuating the brake based on the direction of wheel rotation. The brakes are conventional drum with one leading and one trailing shoe, so the wheel rotation will not have any impact.

By comparison a twin leading shoe brake is designed only for the wheel rotating in one direction, but this is not what the Fantic has. 

The only advantage I have identified to moving the arm to face forward is to overcome a worn brake cam. Changing the direction of cam rotation will use a different face on the cam.

If the drum is true and the linings are good (soft for trials) then the next steps to improve brakes are a longer brake arm, or changing handlebars levers to ones with a different fulcrum distance.

Regards,

Peter.

 

Fantic 200  / swm,  maybe I misunderstood, do they not share marzocci forks and yokes,  grimica hubs and brake plates ? Not relevant ?

Now I see this question has been asked before.

Front brake arm - SWM - Trials Central

From this past forum discussion I see b40rt enjoys sparring and keeping the argument going, then resorts to being personal/rude.

With no other useful contributions evident I will save everyones time and end my involvement in this topic, letting b40rt jump straight to being rude!

Whoa! Handbags at dawn ladies. 

Let's move on?

On 11/26/2020 at 11:16 PM, nzpeterb said:

Now I see this question has been asked before.

Front brake arm - SWM - Trials Central

From this past forum discussion I see b40rt enjoys sparring and keeping the argument going, then resorts to being personal/rude.

With no other useful contributions evident I will save everyones time and end my involvement in this topic, letting b40rt jump straight to being rude!

You'll have to get used to that on here . It's no wonder why very few even bother to look on TC these days .

13 hours ago, motorcycleemptyness said:

You'll have to get used to that on here . It's no wonder why very few even bother to look on TC these days .

Interesting,  a random personal attack criticising spirited debate between friends !!!

Of the dozens of civilised discussions available, you and "friend" chose to comment on just one !  What are your true motives / prejudices  ? 

Edited December 21, 20205 yr by b40rt

Of course it is . Who is friend ? 

 

12 minutes ago, motorcycleemptyness said:

Of course it is .

 

Just answer the question. Why the random personal attack ?

I'm going to try and give an explanation for why, with everything else being equal, reversing the direction of rotation of the brake cam does make a difference to the effectiveness of a cam driven single leading shoe brake.

One working edge of the cam is further from the pivot of the shoes than the other working edge of the cam. It is the outer edge that is further. The outer working edge bears against the outer section of the shoe rubbing pad. This section of the rubbing pad is further from the shoes pivot than the contact section for the other shoe rubbing pad. This means that a rotating force on the camshaft will provide greater force against the drum for one shoe than the other shoe.

On a single leading shoe brake during braking, the geometry of the shoe pivot and the drum is such that one shoe is pulled against the drum and the other shoe is repelled. The one that is pulled in is called the leading shoe and the other is called the trailing shoe. If the direction of rotation of the drum is reversed, then the shoes swap roles.

It is a small effect, but if the bike has the cam rotation direction such that the leading shoe has the smaller of the two forces against the drum, then reversing the rotation direction will increase the force applied to the leading shoe which should make the brake more powerful, with everything else the same.

It's interesting to note which way bikes have the cam rotation which way as standard

5 hours ago, b40rt said:

Just answer the question. Why the random personal attack ?

You got me mixed up with somebody else , don't recall a personal attack ? just an observation . Merry Christmas .

 

7 hours ago, motorcycleemptyness said:

You got me mixed up with somebody else , don't recall a personal attack ? just an observation . Merry Christmas .

 

Merry Christmas to you too, I'd appreciate it you would not use a conversation on a "forum" as an example of the following  - "You'll have to get used to that on here . It's no wonder why very few even bother to look on TC these days ."

Edited December 22, 20205 yr by b40rt