Cheap Chinese Brake/Clutch Levers and Locking Brakes
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From: Kansas City
Cheap Chinese Brake/Clutch Levers and Locking Brakes
Just getting my aging '91 F2 roadworthy again, and a buddy of mine who lives across the country (and road with me to buy the bike back in '91) is doing the same on his old ZX11. A garage mishap bent one of his levers, so he thought he'd just grab a nice looking lever from eBay from some Chinese supplier.
...But, the first day the levers were installed and after riding a couple of miles in town, the front wheel locked up. He was lucky...it happened at about 25mph and he was able to keep the thing upright. He immediately discovered that the front rotors were blazing hot, but why was a bit of a mystery.
Called a buddy with a trailer and got 'er home. We did some chatting on the phone, and here's what we found -
The issue is this: many cheap, poorly designed levers partially engage the piston on the master cylinder. In a properly functioning brake system, the piston is engaged at the master and fluid is pushed to the calipers at the wheel. When the lever is released, the piston is retracted, and it is not until 'just about' complete retraction occurs that the fluid from the actuated calipers can return to the master cylinder (this is by design). If the piston cannot return completely, some tension is left at the calipers, causing heat to be generated at the rotor and the pads and transferred to the calipers, and thus heating the fluid causing it to expand and put further tension on the rotors. What you'd call a positive feedback loop. Eventually the point may be reached where the wheel locks up. There are several YouTube videos of guys who had their brakes lock up because of improperly made levers. Scary...as they're just tooling along and suddenly the whole front end just collapses on 'em. Worst way to crash I can think of.
On my '91 CBR600 F2, an arm of the level rests directly on the master cylinder piston. I have some cheap Chinese shorty levers, and I've compared them to the stock ones. Both compress the piston a slight amount - the stock lever by about 1mm, and the Chinese level by about 1.5mm. Near as I can determine, this in inconsequential. But obviously, 'just' touching the piston with zero compression would be ideal. As far as I can tell, I have the same amount of 'drag' from the brake pads that I had with the stock lever, which appears to be the same amount of drag I see with the lever completely removed from the bike.
I only installed the levers on my own ride a few days ago, before I started hearing about cheap levers being the cause of locked front brakes and before I heard from my buddy 1500 miles away nearly crashing his Kawi. So I've been doing my homework and trying to determine if I have a problem with these levers. So far, the answer is 'no'. But I'll be doing some more testing before I decide whether to reinstall the stock levers or leave the shorty's on. This will include the front wheel off the ground spin test before and after applying the brakes numerous times (easy because of the centerstand put on the bike when I bought it), and doing the same test after some road testing to heat the brakes up a bit. If that looks OK, I'll stick with the Chinese shorty's.
Not all the Chinese levers are junk. Problem is finding out which ones are flat-out junk, which ones are dangerous, and which ones are well-made and worth the effort. And for all I know, even the expensive ones might be problematic...I just have no experience with them, being the budget motorcyclist that I am. I'd make no assumptions about the correct manufacture of my brake lever simply based on the dent it made (or didn't make) in my wallet.
FWIW, started the thread after doing a search and not finding anything. This is a fairly serious deal with the flood of Chinese levers on the market, so do be careful out there.
...But, the first day the levers were installed and after riding a couple of miles in town, the front wheel locked up. He was lucky...it happened at about 25mph and he was able to keep the thing upright. He immediately discovered that the front rotors were blazing hot, but why was a bit of a mystery.
Called a buddy with a trailer and got 'er home. We did some chatting on the phone, and here's what we found -
The issue is this: many cheap, poorly designed levers partially engage the piston on the master cylinder. In a properly functioning brake system, the piston is engaged at the master and fluid is pushed to the calipers at the wheel. When the lever is released, the piston is retracted, and it is not until 'just about' complete retraction occurs that the fluid from the actuated calipers can return to the master cylinder (this is by design). If the piston cannot return completely, some tension is left at the calipers, causing heat to be generated at the rotor and the pads and transferred to the calipers, and thus heating the fluid causing it to expand and put further tension on the rotors. What you'd call a positive feedback loop. Eventually the point may be reached where the wheel locks up. There are several YouTube videos of guys who had their brakes lock up because of improperly made levers. Scary...as they're just tooling along and suddenly the whole front end just collapses on 'em. Worst way to crash I can think of.
On my '91 CBR600 F2, an arm of the level rests directly on the master cylinder piston. I have some cheap Chinese shorty levers, and I've compared them to the stock ones. Both compress the piston a slight amount - the stock lever by about 1mm, and the Chinese level by about 1.5mm. Near as I can determine, this in inconsequential. But obviously, 'just' touching the piston with zero compression would be ideal. As far as I can tell, I have the same amount of 'drag' from the brake pads that I had with the stock lever, which appears to be the same amount of drag I see with the lever completely removed from the bike.
I only installed the levers on my own ride a few days ago, before I started hearing about cheap levers being the cause of locked front brakes and before I heard from my buddy 1500 miles away nearly crashing his Kawi. So I've been doing my homework and trying to determine if I have a problem with these levers. So far, the answer is 'no'. But I'll be doing some more testing before I decide whether to reinstall the stock levers or leave the shorty's on. This will include the front wheel off the ground spin test before and after applying the brakes numerous times (easy because of the centerstand put on the bike when I bought it), and doing the same test after some road testing to heat the brakes up a bit. If that looks OK, I'll stick with the Chinese shorty's.
Not all the Chinese levers are junk. Problem is finding out which ones are flat-out junk, which ones are dangerous, and which ones are well-made and worth the effort. And for all I know, even the expensive ones might be problematic...I just have no experience with them, being the budget motorcyclist that I am. I'd make no assumptions about the correct manufacture of my brake lever simply based on the dent it made (or didn't make) in my wallet.
FWIW, started the thread after doing a search and not finding anything. This is a fairly serious deal with the flood of Chinese levers on the market, so do be careful out there.
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