Weak Front Brake

[SoraXS400]

I've read up on here some, but I can't exactly find the solution.

I have a 1982 DOHC XS400. It has 14k miles and everything is running swell now, I cleaned the carbs and synced them. The only thing wrong with it is the brakes. (Also the bike hits a power boost at ~4500rpm, is this normal for everyone else? Only noticed in 1st and 2nd gear)

I noticed yesterday that there was crap all over the rotor, so I took some brake cleaner and sprayed it all over the rotor and caliper. The brakes are clean and dried off but the front brake is still very weak, as in I can push the bike while completely engaging the front brake. I believe it is because the brake line is from 2/82, but my father on the other hand says it's fine and doesn't expand. When we opened the reservoir at the top, it was very dirty. We bled the brakes, they had decent pressure and came out somewhat clean, but even after that I can still push the bike with a fully engaged brake.

Next thing I did was take off the caliper and checked if the pistons were extending, and they are. Not sure as of what to do right now and this bike is going to be very budget friendly, so I don't know how I feel about completely redoing the brake system. I've ordered some new brake pads for the time being, they'll be in Monday. (4/10/17)

I read up on http://xjbikes.com/forums/threads/why-you-need-to-replace-original-brake-lines-w-pics.41400/ this (Also, how do I embed links into text here?) but I don't want to cut into the brakes if I am not going to replace them right away.

Can someone confirm that I am correct in saying that these need to be replaced? I'm only 16 working on this bike with my father and it's quite frustrating to hear that he thinks the brakes are fine, even though I've done all this research and found that these essentially need to be replaced.

 

[xschris]

If the front brake is that bad, get a new hose, pads and rebuild the caliper. If your dad says its ok then let him ride it on an interstate and see how well that goes. Two things you can't cheap out on is tires and brakes. If either fail at any speed your *ucked.

 

[NewHavenMike]

You can easily get a new brake line for under $75 and probably A LOT cheaper. You can be budget minded on the bike as a whole, but you cant go cheap on your own safety. Id get a new line and rebuild the master cylinder at the very least. Maybe get a better master cylinder to get more pressure.. The stock one should give you enough stopping power though

Manufacture date should be stamped on the rubber. That rubber gets old and cracks and creates weak spots that will split wide open if you need to stop in a hurry.

Check this out:http://xjbikes.com/forums/threads/why-you-need-to-replace-original-brake-lines-w-pics.41400/

 

[SoraXS400]

If the front brake is that bad, get a new hose, pads and rebuild the caliper. If your dad says its ok then let him ride it on an interstate and see how well that goes. Two things you can't cheap out on is tires and brakes. If either fail at any speed your *ucked.

I've ridden the bike on the street (~55-65mph) and I use mainly the rear brake. It's that bad. The caliper rebuild is only $23, hose probably $5 but he insists on waiting for the new pads

 

[NewHavenMike]

Id wait and tackle it all at once too. Nothing better than having everything you need to finish the job in one sitting..

 

[SoraXS400]

Id wait and tackle it all at once too. Nothing better than having everything you need to finish the job in one sitting..

I'm not saying he's waiting, he doesn't want to buy anything for it other than pads. I'm going to dissemble the master cylinder and the brakes and bleed them completely and post some pictures of my results.

 

[SoraXS400]

Attempting to remove the master cylinder has left the damn phillips head stripped.

I'll get this out either tonight or tomorrow

edit: A little update here; I've taken out the screw and taken off the Master Cylinder. Sadly there is nothing really in need of pictures. The master cylinder was clean, and the fluid was somewhat clean on it's way out. There's a picture of the fluid that came out of the lines attached

 

[Jeff0133]

I've bought rebuild kits for master cylinder and brake caliper, and a stainless steel brake line...and OmG does it ever make a difference!

 

[SoraXS400]

I've bought rebuild kits for master cylinder and brake caliper, and a stainless steel brake line...and OmG does it ever make a difference!

Going to Florida today, but getting some stuff ordered.

So far I've ordered a new oil filter and brake pads. I'm going to buy stainless brake lines, maybe rebuild the master cylinder (Doesn't seem like it needs it, maybe just a thorough clean) and then look into the calipers. So far it just seems that the lines were clogged.

 

[NewHavenMike]

Yea they're clogged with rubber bits from the inside of the brake line! All those rubber parts are no good. They are very old.

What is it like using just the back brake to stop when you're going 60mph? Lol just wondering

 

[SoraXS400]

Yea they're clogged with rubber bits from the inside of the brake line! All those rubber parts are no good. They are very old.

What is it like using just the back brake to stop when you're going 60mph? Lol just wondering

The back brake is actually quite good, it was going uphill as well which helped. I made sure to adjust it before I left so I was actually opening the shoes

 

[xschris]

While your doing the front brake I would take apart the rear to clean the shoes and lube any pivot points. Also check the shoes for thickness.

 

[SoraXS400]

While your doing the front brake I would take apart the rear to clean the shoes and lube any pivot points. Also check the shoes for thickness.

Yeah I made sure to do that before I left. Shoes looked great, barely any wear. 3in1 oil and greased up pivoting spots, I'll probably do it again when I remove the rear wheel to get painted. All is well, but sadly I won't be home this weekend to take care of her.

 

[16VGTIDave]

@SoraXS400 when working on your bike, you need to put aside your Phillips screwdrivers and use the correct ones: JIS. Do the research. And when the time comes, present the facts to your dad. The right screwdrivers make all the difference, just like using metric wrenches on metric bolts. Sure, you can use an adjustable wrench (aka nut lathe) or an Imperial wrench, but the results are predictable...

 

[NewHavenMike]

I agree. Even a harbor freight toolset will do the job and they are very affordable. It's just if you plan on getting serious, you should skip the harbor freight and get a decent set. I've had my Stanley 200pc set for around 10 years and its been great, obviously it do any have every tool I need but these are things you acquire over time.

 

[SoraXS400]

@SoraXS400 when working on your bike, you need to put aside your Phillips screwdrivers and use the correct ones: JIS. Do the research. And when the time comes, present the facts to your dad. The right screwdrivers make all the difference, just like using metric wrenches on metric bolts. Sure, you can use an adjustable wrench (aka nut lathe) or an Imperial wrench, but the results are predictable...

I have all the correct tools, the bolt that got stripped was just rusted out and the previous owner tried getting it out with incorrect tools.

 

[16VGTIDave]

I have all the correct tools, the bolt that got stripped was just rusted out and the previous owner tried getting it out with incorrect tools.

Excellent! That has to be the first time I've heard someone new here say they have JIS screwdrivers. Even some experienced bike mechanics I've spoken with didn't know or or have them.

 

[SoraXS400]

Update today. I got the bike back together (I took off the brake and clutch lever to paint, decided to rebuild master cylinder) with new pads and brake fluid, bled the brakes and they are still unsafe.

It seems like the caliper is allowing some grease or something onto the rotor? I'm very confused by this, whether it's brake fluid or some grease (I use gloves when working so I don't know if it was sticky and brake fluid-like).

Do I need to rebuild the caliper? It also seems to move a bit when pulling in the brake, and the brake pressure feels great at the lever and the bleeding screw.

 

[SoraXS400]

Excellent! That has to be the first time I've heard someone new here say they have JIS screwdrivers. Even some experienced bike mechanics I've spoken with didn't know or or have them.

Yeah I figured when I went into Harbor freight one time for some sockets, I might as well buy some. They're decent tools, but I bought some extras off Amazon, they're about the same price as normal screwdrivers so

 

[xschris]

Sounds like the caliper seal is bad. I would disassemble it completely and clean it. Then replace anything that is bad. Once brake pads get soaked in brake fluid they are done. So keep that in mind.