Front brake caliber removal

[maico]

hey everyone!
Someone might already have asked this question, but I couldn't find it.

My bike has two front brake calibers. Now, I'm not particularly fond of the look of brake disks. So I'm thinking "if I remove one, there's one less too look at".
My question is: if I bleed out the system, remove one caliber and disk, will it then still brake as good as any other bike that only has one caliber in front, or do they somehow compensate each other?

Thanks. Maico.

 

[Max Midnight]

I think you mean brake caliper.

If you remove one of the discs then for any given amount of lever pressure then you will reduce the braking applied to the front wheel.
In other words, to get the same retardation effort you currently have will require more effort to be applied to the lever.
If you take that further then the maximum retardation available will (assuming the bike isn't over braked) be reduced.

Assuming that your current system was designed to be used with two calipers then removing one will reduce the ratio of the m/c piston area to that of the calipers. This will affect the feel of the lever and may make it feel more 'wooden'.
Have a read of this.

Given that the purpose of brakes is to stop the rider coming into contact with hard objects then, IMHO, anything that reduces braking efficiency is a bad idea.

That said folk do all sorts of daft things to be in vogue. Some have even been known to remove the front brake altogether which is fine on an oval racetrack but a potential death trap on the road.
Type 'Darwin Awards' into Youtube for more examples.

 

[gggGary]

one rotor/ caliper has worked fine for decades on 100's of thousands of XS650's but you need to match master cylinder piston diameter to caliper pistons. Vintage brakes knows his stuff here's a link to a chart. your MC may be 14 or 17mm

 

[weaselbeak]

Dual systems usually have smaller diameter rotors than a single system. Your one remaining rotor will have less power than the appropriate single disc setup. You should source the entire single rotor and caliper if you make the switch.

 

[Paul Sutton]

Look below the master cylinder reservoir, in front of or close to the name NISSIN will be the piston size. As gggGary said you may see a 14 or 17 for millimetres diameter written there. You may even see an Imperial number like 5/8 inches diameter. Let us know and include a photo of one caliper close up and the diameter of the rotor in millimetres. Then we can make a good judgement on what the impact on braking will be.

As others have said, if you have an original braking system then the removal of one rotor/caliper will give a mismatch between master cylinder and caliper cylinder surface areas with a drop in braking performance. The mismatch becomes most noticeable when braking suddenly or at out of town speeds where the brakes need to dissipate more energy.

 

[5twins]

One more thing - everything is installed backwards on yours. Calipers originally mounted on the front of the fork legs and the axle clamped/inserted from the left side. Someone flipped your fork lowers around and switched them side to side to get the calipers on the rear. You lose the function of the speedo drive like that because now it's on the other side and runs backwards.

 

[Paul Sutton]

Could that be a useful technique to lower the mileage. In the UK some people used to connect their vacuum cleaner to their gas meter so it would wind back and lower their bill. The ingenuity of some!

 

[gggGary]

TX650 has 2) 48mm pistons per caliper so by the chart and guidance from Mike

"For 2 piston opposed calipers, I like ratios in the 27:1 range, feeling some line and caliper flex. For a firmer lever, use 23:1. I think ratios lower than 23:1 produce a lever feel so "wooden" as to have little, if any feel. Combine "low" leverage ratios with sticky pads, and unpredictable lockup is the result. The high effort required at the lever also results in undesired input to the bars. Single piston calipers are much happier in the 14:1 to 12:1 range. Disc and wheel diameters, as well as hand lever ratios, must be considered."

So with one caliper about a 13mm MC is ideal, for a twin caliper setup You'll have a hard time finding a big enough MC.
Were it me I'd be researching a single lightweight rotor and spacer, or add a Brembo caliper conversion. Going to a single modern lightweight rotor could cut more than 9 POUNDS of unsprung weight off your current setup!

 

[650Skull]

There needs to be some more information about the bike and the front set up. model ID is imperative

Is the bike an import or an local Danish sold bike.

looking at the front fork, it looks to be an XS2. From the knowledge i have the XS2 did not have a hub that could take a twin disk set up and the 72 fork and caliper is a one year only set up that does not interchange with any other year/model.............. The caliper is mated to the fork.
XS2 fork thread http://www.xs650.com/threads/xs2-front-axle-assembly.31433/

My reason for this question is the mount for the guard brackets in your pic are very low on the fork, as per an XS2. In 73, on the TXA the guard brace mounts on the fork leg was raised. This means the guard braces between the 72XS2 and 73TX are a different length and do not interchange.

Need more pics from both sides and showing as much information about the hub and forks as possible............Until this is sorted any other information may be mute for your situation...........

also a single disk set up without any guard or fork brace of any kind will put a lot of unbalanced force on one fork leg when braking.

72XS2.........................................73TX............................

 

[mrtwowheel]

Swapping the forks to different sides like that would not make the speedometer drive run in reverse unless the wheel was also reversed. I mocked up my TX650A that way and I don't see anything wrong with it, only two addition things to check when assembling, the angle of the speedometer drive (so that the cable takes a reasonable route), and checking the clearance of the caliper to rotor (same as is done with any two caliper front end). The speedometer drive does not need those locating dogs on the forks, after the axle is tightened the speedometer drive is virtually a spacer bearing on the axle nut and wheel bearing.

I've asked why this fork swap couldn't be done on other peoples threads with no answers. With all of the chopping, bobbing and building going on, I am honestly shocked that this isn't common on the '72-'76.

When I mocked mine up with straight forks this way, forks swapped, axle reversed, rotor and caliper on the right side, the rotor was dead centered in the caliper with no tweaking.

I'll also be drilling out the flare in my caliper to accept a few more threads of a cut off M10 x 1.0 banjo bolt.

Scott

 

[gggGary]

Skull, minor quibble the 73 is a TX650 the 74 is the TX650-A at least here in North America, I hadn't noticed that fender mount diff! Would be interesting to see the other side on the OP's bike, the other 72 leg, axle, spacers rotor carrier etc,, etc. are pretty goofy.
Mr motowheel the factory moved the calipers to the back in 76. There's lots of fork changes 70 to 78 when it finally settled down to the end of production. In those years AFAIK only 74-75 are identical.

 

[650Skull]

Skull, minor quibble the 73 is a TX650 the 74 is the TX650-A at least here in North
America

just checking to see if you knew....


Edited the post.

 

[650Skull]

Going through the brochures and pics of 34mm forks, Euro and other countries, i have come across the information that those 34mm forks are not only swapped from the right side to the left but the Euro early twin disk rotors are smaller in diameter, (compared to the US and other countries single disk brake rotor), and that is why the guard stays are mounted lower on the 34mm forks. the fork lower is actually a Euro spec 34mm lower front fork, as are the rotors.

I will post up pics later today


maico, measure the size of the rotor. Still would like the Vin no, but my earlier assertion your front may be a 72 could be wrong now i have found the Euro 34mm forks are different to the rest of the world.