Pattern Brake levers for NC29 - caused my brakes to seize

[vr46]

Hi All,

I've never heard of this before, but after speaking to some of the guys at a race meeting this sorta thing has happened before and actually caused a guy to get killed whilst racing at Croft some time ago... So I've been told.

I bought some "Bike-it" pattern levers for my NC29, by all accounts these were a direct replacement. They were fitted along with bleeding the brake system and resetting it with Dot5. Brakes came up fine and I thought they were good.

I started out on track; I couldn't hold any of my lines and after a few laps I could feel the bike slowing, luckily the red flag was out for some other accident so we all pulled off track. On slowing down I could feel the front brakes binding and when I rolled to a stop the front brakes then seized on solid and the front brake lever was rock hard with no feel at all. After the bike was stood for 5 mins + the brakes free'd up.

I could not move the bike!, lucky I pulled off when I did... I had no clue as to what had caused the problem, after much running around and swapping master cylinders we were informed by another guy that the lever was the problem. When the lever was in the open position it was pushing in the piston to the master cylinder very slightly, mabe 3-4mm and after continous braking it was not allowing the return of fluid quick enough. The fluid that was in the lines and calipers was heating up and applying the brakes.

Anyone else heard of this happening? I'm new to the bike and to club racing - this was meant to my first outing but I only managed a practice session for the whole day. We did adjust the lever but by the time we had figured out the problem my day was over.

[ADW116]

Hi,
we have come across this problem with pattern levers on the NC29 that I spanner on, the genuine lever has a curved face on the master cylinder activating part, and also the accuracy of the casting on some pattern levers leaves a lot to be desired!, having had this problem a few years ago on a TZ125 at Croft and found the same thing on the replacement lever we put on the bike at the nw200 this year it is always best to check that you have a small clearance on the lever as this means the fluid return port is open and preferably get one with the curved face if you are not using genuine parts.

[sa.racing]

Yes unfortunately this is a very common problem (believe it or not also with genuine levers) as ADW116 has Said you should always have a very slight air gap between the lever and the piston (free play) this is to allow for heat expansion but also ensures the piston is not being slightly depressed causing the above mentioned problem a few minutes with a file/angle grinder every time you fit a new lever is time very well spent but be careful only do a little at a time as you only want a small air gap just enough you could measure with a rizzla paper
PS on a side note Genuine Honda levers are available from David silver spares for really cheap and there much better quality (but still need a little tweaking but not as much)
http://davidsilverspares.co.uk/parts/ge ... art_11098/

[vr46]

Thanks for the replies, I did not know it was such a common problem!

Well; I'm learning all the time :)

I'm going to go for original levers from now on! and I'll check the air gap when fitting new levers.

Thanks

[brys]

I had EXACTLY the same problem at a trackday at Mallory with Focused events about a month ago. Brakes were binding after 2 laps and the calipers were so hot you couldn't even touch them! Upon investigating it looks like it was a combination of sticky pistons and aftermarket brake lever. I polished each piston up on a polishing wheel to make them real slick and they move easily in the calipers now. A non standard lever was also to blame as it just closed the M/C slightly, best to experiment with levers. Get the front wheel off the ground and pump the brake a few times, then spin the wheel as hard as you can. Note how long it takes to stop. Pump the brake again only this time spin the wheel and push the lever forward to allow the M/C to open fully. If the lever is closing the M/C you will hear and see the wheel spin for longer.

Hope it makes sense!