Rear Brake/ too fat?

[Grumpy old man]

Hi kids, A while ago I inherited my wifes old Grand Vista and after one trip with the rear brake barely working it was to the mechanic who replaced the master cylinder and bled the brakes new pads and then told me to seat them with some long stops at speed, which I did the second day of use in fact I may have over heated the dot 3 fluid since I pretty much had no brake just a useless lever but after cooling they seemed better.

  Here it is months later and I am getting pretty frustrated with the rear brake it just isn't getting the job done it functions pretty normally but from any speed above 10 mph you can't squeeze it enough to lock the rear wheel the lever will touch the grip.

So is there a replacement brake disk( larger diameter)  or a way to mount a second set of calipers to the rear end.  I loved the brakes on the People 250S by the way.

And a note about Dot 3 fluid didn't this go out with the dinosaurs?  why not use Dot 4. both are virtually the same chemical with an additive to retard dry boiling by another 30 to 50 degrees c.

 
     

[BettinANDlosing]

Hi kids, A while ago I inherited my wifes old Grand Vista and after one trip with the rear brake barely working it was to the mechanic who replaced the master cylinder and bled the brakes new pads and then told me to seat them with some long stops at speed, which I did the second day of use in fact I may have over heated the dot 3 fluid since I pretty much had no brake just a useless lever but after cooling they seemed better.

  Here it is months later and I am getting pretty frustrated with the rear brake it just isn't getting the job done it functions pretty normally but from any speed above 10 mph you can't squeeze it enough to lock the rear wheel the lever will touch the grip.

So is there a replacement brake disk( larger diameter)  or a way to mount a second set of calipers to the rear end.  I loved the brakes on the People 250S by the way.

And a note about Dot 3 fluid didn't this go out with the dinosaurs?  why not use Dot 4. both are virtually the same chemical with an additive to retard dry boiling by another 30 to 50 degrees c.

 
   

I think they replaced the wrong part, sounds more like a bad caliper not master cylinder. The breaks on that bike should be rock solid. I drive VERY aggressively and have NEVER EVER overheated my brakes, and I drive the Bet And Win, pretty much the same bike as yours.

[windwheeler]

I think they replaced the wrong part, sounds more like a bad caliper not master cylinder. The breaks on that bike should be rock solid. I drive VERY aggressively and have NEVER EVER overheated my brakes, and I drive the Bet And Win, pretty much the same bike as yours.

Bet&Lose is right, they did "something" wrong. Should be rock solid lever and throw you off the bike with a high or low side when the rear-wheel locks up...    

[mrbios]

  Here it is months later and I am getting pretty frustrated with the rear brake it just isn't getting the job done ...

How many miles on your scoot?

I agree with B&L & WW'er.  Absolutely no need or value in adding a caliper or changing to DOT4.  I have a very hard time believing the master-cylinder went bad.  I have 16K miles (not Km) on my 2005 GV250 which I bough with 2600 miles on it 3 1/2 years ago on craigslist.  For sure you have air in the lines and I suspect the caliper has been the problem all along. 

Here's the deal.... when I replaced my rear brake pads last year I accidentally split the rear caliper because for some strange reason the rear caliper is two parts held together by two bolts and it is easy to accidentally remove or loosen  a bolt that should never been unbolted unless the caliper is going to be rebuilt. 

Solution:  I noticed liquid (brake fluid) leaking realized my mistake tightened the bolts, wiped the mess up and bleed the brakes.  It multiple bleeding before I got all the air out and returned to a normal hard brake lever that does go to the handlebar and easily will lock the rear wheel.   

1. I recommend inspecting the rear caliper for leaks or stains from brake fluid escaping. 
2. re-bleed the rear brake with the scoot on the center stand - but be sure to have someone monitor the reservoir as it is tiny and can run dry quickly causing more air to enter the system ( it happened to me ). 

Report results.

[windwheeler]

Very good point Mrbios, air in the line would explain the spongy feeling he has.  Bleeding is always best do be done with a "helper" to watch enough is going in, and "no air" is finally coming out... Or, one has this "auto bleeder" that works on suction (great for cars), the only thing for motorcycles they suck through the brake fluid like the Danube runs down stream...   

[mrbios]

Very good point Mrbios, air in the line would explain the spongy feeling he has. ...

Thanks WW'er.  Off topic question.  Replace the caliper in my car and some how got air in the system.  Two bleeds and life was good again.  Stomp on the brake and the ABS comes on.  Recently, I pressed the brake hard and it failed to lock up on a wet surface!  Do you think it is air in the line OR the master cylinder?  Original owner 1997 Saturn SW2 with 160K.  I noticed for the past few years a tiny leak of brake fluid from the master cylinder.