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Motorcycle brakes

4K views 25 replies 7 participants last post by  Cyorg 
#1 ·
Should brakes be getting stiffer as you ride? It's been happening to me and I'm a bit worried that it's going to lock up. It'll get stiff and then drag the brakes. I stop for a bit and then the brakes go back to it's original stiffness. I changed my handlebars so now my brakes lines have more slack. Could that be a reason?

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#3 ·
Hydraulic brakes? Change your brake fluid it's hygroscopic meaning it absorbs water from the atmosphere. It only takes ~4% water content to be useless. Water boils at a lower temperature then brake fluid, brakes get hot, the water boils and makes steam inside your brake system :| (you just built the worlds smallest steam engine) Brakes drag because of expansion in the fluid and that promotes even more heat which amplifies the problem.
Bleed the brakes off and the problem temporarily goes away until the next time the water gets hot.
 
#6 ·
Not sure what bike you have (pro tip: when you ask a tech question, ALWAYS include year, make, and model) but while you are in there you might as well inspect the caliper piston and grease any brake pad slides you might have.

Also take a guitar string and clean out the return hole in the master cylinder.

To me it sounds not like a "heating" problem but a "retraction" problem - your caliper is sticking because everything is dry, or the piston has corrosion on it and isn't retracting as quickly.
 
#7 · (Edited)
Although you likely need a fluid flush, you will probably find that the piston in the caliper is either gummed up or corroded and it not returning properly when you release the brake. It generally gets worse as you ride. You need to take the caliper apart, clean it out and check it for pitting. It may survive with a cleaning and new seals etc, or it may need a new piston, or you may have to toss it and get a new one. No offence, but if you are asking about cable slack, you need to be very cautious about brake work and if you are going to do it yourself, have someone who knows how to do it look over your shoulder.
 
#8 · (Edited)
Geeto can type faster than me.


ps

If you do go inside there, this stuff works well with the rubber bits and won't do funny things when exposed to brake fluid..... although exposing it to brake fluid shouldn't be an issue, because you are using a very small amount. I use this stuff for the bits inside the calliper. There are better things to use on external bits like caliber pins.

You can search around and find a smaller container for less...or its possible if you buy a rebuild kit, it will come with enough of this stuff. So you can order the kit first and wait and see if it comes with the proper grease.

+1 on the guitar string.

https://www.ebay.com/p/4-Oz-100-Pur...se-Brake-Caliper-Piston-Seals-Boot/1389852637
 
#11 · (Edited)
No, not unless you completely kinked the hose and I was giving you the benefit of the doubt that you wouldn't do that. Plus you would have to work at kinking it that much. Too much hose can create places for air to hide and make bleeding more difficult, but that will give you spongy brakes not sticky ones. If geetos tip for clearing the return hole in the master cylinder works, it could be an indication the master cylinder could use a kit as well.

I suspect the fact that it started when you swapped the bars was just coincidence. How much did you ride this thing prior to swapping the bars?


PS... I just went downstairs and grabbed an old brake line off a 82 GL500 to see how sharp a bend it would take. It would take some doing to restrict the flow that much.
 
#12 · (Edited)
I assume we are talking about your 82? 450T if so, it is over due for brake rebuild kits if they still have the original stuff in there. You can make a nice bike out of that BTW, so don't fuck it up.
This is a 400, but probably worthwhile for you to read. https://www.caferacer.net/forum/project-builds/39623-cb400t-shitbox-build-daily-driver.html



If you have images like this in your head, its probably best if you don't come out of the closet.

https://www.returnofthecaferacers.com/honda-cafe-racer/never-idle-thassophobia-honda-cb450/
 
#18 ·
It's more likely the slider pins and slider bracket are corroded and locked up. The brake drags and heats fluid causing even more drag and heat, etc. Used to be a pretty common problem when they were 3~4 months old as British riders tended to ride all year unless the snow was too deep
 
#20 ·
Good point and one that reminds me not to let geocentric thinking get in the way. Where I live, slider pins as the cause would be much lower on the list. They would get a good cleaning and the proper grease on the way back together, but don’t recall seeing pins as the main problem. Has to do with geography. Salt or anything corrosive on the roads here is rare and you don’t get those types of problems. Did my sticking GL brakes and pins were fine. Hauled an 81 911 SC Coupe out of the weeds that had sat for about 14 years. Pistons stuck...pins ok. Now in the UK, or Ontario where Trials and Woodsman live is a completely different story. Those two probably have to shower twice a day to get the rust off.
 
#23 · (Edited)
Yes you must be looking at the owner's manual. I don't have a 450 manual, but pretty sure the trouble shooting section in the back won't mention brakes, probably just engine performance and handling... but if you go to the actual section on brakes, the index there will indicate what page the brake trouble shooting info is on. Usually the beginning of the brake section... go figure. This is CBX and all the other factory Honda manuals that I have are similar. It looks like this only not cockeyed;

Text Font Paper


Interestingly enough, they don't mention pins, but to get to the pistons, you'll be finding out what the pins look like anyway. Guess they weren't thinking of the UK or Ontario when they wrote it. One thing that you need to keep in mind when using the factory manuals, they weren't written with you in mind. They were written for someone in the dealership like a certified tech, so they may gloss over or skip things than are considered basic knowledge or procedure. The manual does go on to describe how to disassemble, measure, and reassemble them, but you need to buy your own manual. Generally speaking IMHO factory manuals are better although sometimes harder to find and more expensive.
 
#24 ·
If the brand of bike was mentioned I missed it (back from two weeks vacation with no forum surfing and scanning to catch up) so maybe this won't apply, but here goes. In the world of Brembo master cylinders whenever someone says their brakes tighten up when riding, the conversation usually reveals the poster just replaced the brake lever or adjusted the play out of the stock lever. In doing so one of the ports in the MC gets blocked and the pressure builds to where the brakes start to drag.

So... is it a Brembo MC? Did you adjust the lever when you replaced the bars? if so, put some play back into it and problem solved.
 
#26 ·
It is a early 80's 450 Honda I think. Also "think" it has the stock M/C, so not the adjustment.... but good point. Always possible the lever was mangled or replaced with used or aftermarket and doesn't have sufficient clearance for the piston to return.

I was going to ask you an exhaust question the other day, but can't fucking remember what it was....
 
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