I have a 98 gsxr 750. I am having an issue with my front brakes. I know the pads are thin and need replacing but the brakes dont grab right away. I have to pump the lever several times before it grabs and this happens everytime I need to brake, the same way. Even with the thin pads they should still grab, right? Does this sound like air in the line or just master cylinder is gone. I REALLY hate down shifting and using rear brakes but it still does the job, just feels unnatural,lol. Any suggestions are greatly appreciated
most likey yes its about to break so stop driving or you be walking so
New pads. New fluid. Bleed brakes. That should cure it. Do this test first though. If you can pump them up and they hold pressure, you probably don't need to replace any parts. If you pump them up and then the lever slowly sinks, you probably need a master-cylinder rebuild.
New brake pads should be your first step, followed by bleeding the brake system. Assuming that your hoses and master/slaves are in good shape, what happens when you wear down your brake pads is that the pistons in your brake calipers hyper extend because there is less brake material holding them back. This means that more fluid is pumped into your caliper, and thus there is less fluid in your master cylinder since there is only a finite amount of fluid in the system. If your master was low to begin with, you could introduce air into the system, making the brakes spongy and ineffective. So, short answer, throw some new brake pads in there and bleed the brakes. Your repair manual should be able to tell you everything you need to know.
I had a customer in my shop with the same problem. He had the brake system bled and re-bled til 100% no air in the system. But the first time using the brake the same problem would return. Diagnosis - warped disc rotor. Center stand the bike and prop the engine. Spin the front wheel and check brake rotor for warpage. If it is more than a few mm, (check manual for maximum tolerance), that is the root of your problem. After you release the brake lever, the warped rotor causes the brake pads to separate more than necessary (double the mm warpage) so that the next time you use the front brake, you need to pump the lever several times to close that gap for the pads to act on the rotor again. Solution. Not much you can do but replace them. If you are buying used or surplus rotors, lay the rotor on a flat surface, preferably glass, and use a feeler gauge between the rotor and class to check for warpage. You can do the fix yourself if you are handy with tools. And replace the pads, too. Good luck.
