BMS TXB 260 front brake goes very bad! By prodigit (Read 1,231 times)

[prodigit]

On these types of bikes, how's the front brake supposed to brake?

I have the feeling overall the front brake only does 10-20% of total braking, rear brake ~50-70%, engine braking the rest.
The rear brake brakes like normal, but I have to pull the front brake like a muckerfugger to actually enable the ABS.
Is that normal?

Like, I'd have to pull the lever so hard, that a mechanical cable brake would have been pulled over already, and nearly 80% of my total grip power (which is a lot, since I have ~90LBS of max grip power in each hand).

I have the feeling my front brake is working only 50%...

Wasn't always like that; though I have to say in the beginning, the front brake always braked less well than the rear, now it's like if I'd use only the front brake to come to a stop (like I would on a bike, or other cycle), it brakes worse than engine braking at lower speeds!

Anyone else has the same experience?

[wheezy]

On mine, I wouldn't guess as low as 10%, but it's certainly not a 50/50 split. I'd say more of a 70/30 rear to front. Once I set my front in a braking situation, it's enough to stop the bike on its own, albeit a little longer distance.

If your pads and rotor are in good shape, perhaps doing a full fluid replacement, rather than just a normal bleed, may help. It's time-consuming and tedious, but at least that would be one variable eliminated.

[justbuggin2]

i would say that your master cylinder is in need of rebuilding or replacing

[richardthescooter3]

I have a mc-54-250b roketa scooter, the front brakes are hard to squeeze, I thought I read that it was because of the short distance of the cable to brakes.

[jct842]

The first thing I would suspect is the phony abs. All it is is a bypass so that you can not lock up the front brake. Your front brake is supposed to do most of the braking. If I had a scooter with phony ABS on it when it was delivered to me, it would be taken off before I even took it for a test ride.

[cruiser]

Well, I guess we all know that the front brakes are supposed to handle most of the braking job. Once the weight shifts under braking, the rear wheel has less traction than the front. High performance motorcycles have enough braking power in the front where they can lift the rear wheel off the ground.

As wheezy suggested, changing the brake fluid is a good idea. Many people have felt improved brake feel and performance after doing this.

Like John (jct842) says, removing the fake ABS would give a true feel of what the front brake is doing. With the fake ABS you will never get a firm linear feel to the brake which is what you get with the rear brake. This is why the rear brake feels like it has more braking power.

[prodigit]

Problem is I don't even get near to ABS brake pressure, and it just does not cut it.
Like, the rear brake can stop my bike in 6ft at a certain pressure from a certain speed, the front brake will need over 6-7x that distance at the same pressure.

When I opened the front brake fluid box, oil came pouring out, as if it was under pressure???
There's also not a single air bubble in the front, while the rear brake reservoir has a small air bubble behind the glass (so I can see the oil level).

I know next to nothing of brakes, and the last thing I want is trying to change brake pads, and end up losing all the oil or something...

As far as the ABS, it once came in handy. Back when the brake pads where still new, they worked a lot better, and I had to stop quite hard on a corner of a street. It just started raining, and my wheel locked up on the pedestrian crosswalk (the white painted lines) when I got over it.
The ABS kept my tire straight. I don't really want to get rid of it!

I never was able to tilt the rear wheel by applying the front brake, I thought that was only for racing bikes (mine is more like a touring/luxury scooter, so I can imagine rear weight to be a little higher than a sports bike).

[jct842]

It would be a good idea to take your scooter to a shop and get your front brake repaired since you don't want to mess with it. Riding it the way you describe can get you killed. The rear just does not have enough braking power to stop in an emergency situation. and this goes for any bike, you need the front brake working right.

[kz1000st]

I second what John said. The balance front to rear is more like 80/20. There's a reason many bikes come with drums in the back. The front is supposed to be doing most of the work. High performance motorcycles have two discs in the front for a reason.

[cruiser]

John and KZ have good advice. You may have a frozen piston or caliper. If you are not comfortable working on brakes, then go to a shop that can repair it. Brake systems are fairly easy to work on but experience is needed to avoid problems.

[prodigit]

Update on the brake!
I can't find a single scooter mechanic, in about a 25 mile radius that is willing to work on this bike!

I just noticed, that after a hard squeeze, the brake brakes normal for a while (meaning I can squeeze soft after a hard brake, and it will brake normal). When I drive on a stretch, the brake goes back to hard mode.
In other words, it's almost as if something goes loose inside, when I brake hard; only to tighten again a few tens of seconds later!

[jct842]

I'll say this again....if you keep riding a scooter with no front brake you are going to get your self killed. When you say you put 90 pounds of squeeze on the lever I would be tempted to replace the whole front brake system as you have put many times the force on it than it was designed for. The pressure that lever normally gets is ounces to a few pounds. The fake ABS is still a very good possibility for your problems, I would get it removed so you can feel the braking. If you have to take it 200 miles to get it repaired that is going to be a lot better than bending up that scooter. If that thing is new you could try to call the seller to see what kind of advice he can give you on the repair. That brake has to work every time you put pressure on that lever.

[prodigit]

I've never actually put 90 pounds of force on it, but if I squeeze the lever on the outside, i have to press it a little bit harder than usual (few pounds). Normal squeezing, or squeezing it on the beginning of the lever goes very hard, like about as hard as you'd squeeze a foam stress ball.

I was also thinking it could be the ABS system. Perhaps some of the pressure got into a reservoir, and is now pressing back against my normal brake use, however, it would make very little sense.
There's definitely something wrong, I suspect with the brake cylinder, but since I don't know enough, I can't exactly tell what.

[prodigit]

Another update;
Funny but true, it was raining today, and the bike was outside for a while.
When I drove off, the front brake worked like normal again, which leads me to believe there's either rust in the cylinder, or oil on the brakes. With the rain water, the cylinders might slide better, than without lubrication. I don't know if this makes any sense though...