SAFETY check-brakes

Hi all, after my accident and doing some investigation of why it occured (my front right caliper locked up) I wanted to post what I found so this doesnt happend to any of my fellow XJers (other any other riders). I knew the right caliper locked after looking at the bike and seeing the heat marks on the rotor, but why is what I needed to know. I visited 5 local shops and heard some of the same and some different opinions as to possibiblities, everything from incorrect bleeding, interior collapse of old hoses, worn caliper parts, and dirty fluid. But ALL of them mentioned one possibility which I indeed have now found to be the case. There is a small pressure release valve in the system, that can be clogged by dirt elements from dirty or old fluid ( I flush my brake fluid every year simply by draining and running new fluid and bleeding, which always seemed to work fine) and when this gets clogged and you are driving heat from the rotor heats up the fluid in the caliper expanding it, and with this clogged only thing for it to do is push out causing the brakes to grab, and grab hard! I also learned from these shops that it is more common than thought they all had stories of people they knew having this happen, most at around town speeds 30-45 after cruising all day (unlike lucky me at 85mph LOL) They suggested especially on older bikes getting the system fully cleaned (ie. pulled apart and soaked, rubber replaced etc.) any way this was news to me so I wanted to post for those that did not know like me. Ride safe all.

 

Good post Regulator, and yes, every old bike has a very tiny pressure release hole in the master cylinder. It should be noticable as you ride around you may notice the brakes take less pressure to come on as the system remains pressurised.

For those who don't know about it I suggest some weekend maintenance very soon.

Commonly known as the "spooge" hole on XS11.com, they have some great descriptions and pics of the well known problem.

http://www.xs11.com/tips/maintenance/maint28.shtml is a good starter.

 

Thanks Hired, and thanks for the link!! now that I am up and about, I was hoping to get some info on a way to clean other than paying the shop (but i would have LOL) Also I (as was told) would recommend replacing brake hoses that are over 5-7 years old as the inside can collapse or wear with no external signs of damage. Again I knew about this on cars but always overlooked the simple things on my cycles. thanks again Hired for the info

 

Question: I would think that regular bleeding and fluid replacement like what you did would prevent this?

According to the XS site, it comes from gunk floating around.

Do you think that maybe you had water intrusion that caused rusting? Or do you think that some rubber came off the interior of a hose due to age and blocked the hole?

I am interested because my brake lines are original to the bike!

 

The lines do break down. It has been noted a few times that the disclolouration and contamination of the fluid is actually caused by the brake lines breaking down. My XS manual's brake specifications claim to relpace lines every 5 years.

Now bear in mind our bikes are over 25 years old, how many times do you think the lines have been changed.

Bend your lines over, if they show signs of cracking then they are way overdue. Not sure if I'm a great beleiver in the lines restricting but as most brake lines are a double layer I'd be more worried about a bursting line from an aged line.

 

Very good info... I'll check over the bike I sold. Lines looked good and I've recently flushed the system.

I think Casey has yet to decide which bars he's going to use - currently Seca bars are on it but I'll switch them back to stock maxim bars if he'd rather... after that decision is made new brake line discussion might be possible. Certainly the steel braided ones would improve the front brakes... I've always found the maxim brakes lacking when compared to the newer sportier bikes.

[Switching from the CBR back to the maxim took as long as switching from the maxom to the CBR. I forgot just how smooth the engine was].

Horrible thread jack- great post - I'll be looking for this too. Brakes are a little too vital to wait for failure on

 

Just took my front brakes apart and did like the shop had told me and took everything apart in master cylinder, sure enough there was gunk in the pressure release, as well as the right side bleeder screw, also found some very worn seals. Richard, I looked close at the gunk and most looked like micro bits of rubber, and some (very little) like plain old dirt, parts were not rusty at all but coated with gunk, looked thru hoses (after cutting off ends. Im replacing them) and could actually see the inner walls were breaking down. Another tip the shop told me was when installing rebuild kit, or reinstalling good parts, to use diode grease (same as on electrical wires) NOT regular grease or similar, the diode grease will help protect the diaphram, spring etc, but will not interfere or harm the brake fluid or system. Brake line hose for these bikes seem to be pretty spendy if anyone knows of a decent priced place to get would be appreciated I have only found braided replacement hoses starting at about $128 but that even seems a good price now that my wounds are healing up and soreness is leaving my body. LOL

 

Is this pressure release hole in XJ750 master cylinders? If so, where? I sure don't find it in mine........

 

Regulator, you can find good brake components at BikeBandit.com as well as a few other sources. The grease suggested to you is a silicone grease that rubber likes. I would only use it to lube up the parts if your going to run DOT 5 fluid (silicone based). For reassembly, use fresh brake fluid or brake assembly fluid (yes, it exists but Lord only knows why I bought it). Braided lines are the must have replacement for your dying lines. Galfer makes a fair set.

 

Robert's right Silicone will react with any brakefluid other than silicone based brake fluid, causing the rubber parts to get soft and break down.

Regulator, sorry to hear of your accident, but I do appreciate the heads up to the rest of us. It's easy to skip over something so important on these older bikes.
Those rubber brakelines do wear out due to age and contact with the brakefluid. People dont usually think of a hose as subject to wear like other moving parts.
Remember that the fluid in the hose, under hydraulic pressure is a moving part.

 

I replaced my master cylinder last year (probably could have rebuilt it. my front brake was sticking, I didn't know about the release hole.) I really like having a nice clean site glass though because the brake fluid turned yellowish brown. I figured my brake line was breaking down inside. I replaced it with a stainless steel line there is a ton of difference now, much firmer. the line cost about $70.00, worth every penny. my 550 only has a single front disc so others will be more.

 

I replaced my master cylinder last year (probably could have rebuilt it. my front brake was sticking, I didn't know about the release hole.) I really like having a nice clean site glass though because the brake fluid turned yellowish brown. I figured my brake line was breaking down inside. I replaced it with a stainless steel line there is a ton of difference now, much firmer. the line cost about $70.00, worth every penny. my 550 only has a single front disc so others will be more.

 

You need to let us know where you got a line that enexpensively.

 

I agree

 

I'm sorry Hvnbnd, I don't wish to step on toes but silicone will not harm rubber, it is an excellent lubricant for rubber. Were you perhaps thinking of brake grease maybe? My concern is that I am unaware of the chemical reaction between regular brake fluid (usually a petroleum distillate, which is detrimental to rubber) and the silicone (darn it, I should have taken chemistry in school) and would rather err to the side of caution. Any of you scientists out there got an answer?

 

Well in our shop the experience had been that if you change a system from regular brake fluid (dot3) and switch to silicone fluid that the rubber parts in the braking system will turn soft and fail.
We learned this the hard way.... I don't know about silicone grease, but it did cause us problems switching fluids.

But we never did switch out the rubber brake hoses just the wheel cylinder and caliper and master cylinder rubber parts.

I wish I took chemestry too, then I'd have a better clue!? I may have been a chemical reaction from not getting all the old dot 3 fluid out!?

Someone out there will know the answer to this.

 

The instructions I have for DOT 5 specifically spell out that any system that has used DOT 3 or 4 must be completely flushed with alcohol and all rubber components replaced with new parts. Not being a chemistry major I can assume from this that there is some sort of reaction that causes rapid degradation of the rubber parts. Scary thought, not something I would want to risk. The silicone grease has a multitude of uses (still trying to get those carbs on? 'Little dab'll do ya, they will slip right in). Spark plug boots and lines, o-rings, etc... Hope someone does provide us with some information on this question.

 

yup a cwemikal reeation.....