Brake system

Hi everyone yesterday I went to change my front brake pads and when I was turning the piston back in they didn't want to go. Once everything was back together I had no brake pressure pumped it till I got them back and they feel terrible. I'm assuming I need to rebuild the calipers and the master cylinder. What parts do I need along with the kits chacal sells. Thanks in advance

 

I bought a hand operated vacuum pump for bleeding brakes a few years ago. Really saves time when bleeding a system from dry, one of the best tools ever.
If your brake system is all original you'll want to rebuild the master and calipers, may as well get some SS lines while you're at it.

 

I'm about to do the same build over the next few weeks. I may also upgrade the rotor like fitz (pictured here: http://xjbikes.com/forums/threads/fork-boots-and-avons-and-real-brakes-oh-my-updated.16019/)

What bike do you have?

Side note -- I have SS brake lines but I can't find SS clutch/throttle/choke cables in Chacal's store.

 

Always forget to put it in my posts its an 81 seca with the anti dive system

 

You may need to pull calipers , and disconect the banjo bolt . Use a grease gun with hose threaded into place of the banjo bolt, and drive the piston out. It is messy but works once out clean out grease and replace seals and check make sure inside is not corroded. Last year I upgraded to SS lines on my 82 xj750 seca and did this , after doing this my piston action was great . Before the seals were hardened and had a little corrosion in bore. So this was overdue , I recommend a one man bleeder , it is a little bit of a challenge to bleed the Seca brakes but can be done.

 

Yea the right caliper is shot. I have good brake pressure though which is odd.was wondering if it's a good idea to do the whole brake system while it's apart calipers and master cylinder rebuilds

 

All the seals and hoses are 30+ years old. They were spec'd to be replaced every four years.

 

And make sure you are bleeding from the bottom most part. If you don't get the air out of the anti-dive, you'll never get bled

 

^^^+1 K-moe replace brake hoses if they are original pull back spring cover you will see a date stamp chances are 81-83 way past due for replacement. Do replace and rebuild caliper , the seals are usually bad they keep the piston from releasing and can cause brakes to drag and pads to wear out . If your piston is pitted this is the time to find out as well. I lucked out my pistons were in good shape, used a grease gun and drove piston out( NEVER USE VISE GRIPS OR CHANNEL LOCKS) , had some corrosion in bore , used my dremel with a brass wire wheel and cleaned nice ( Brass is soft and won't "cut" into the metal ) . Put in new seals and installed new SS lines from xj4ever ,bleed system and my brakes are so much better ( brakes drug before I did this , no longer dragging afterwards ) . By all means do the upgrade yes it requires 4 lines , the upper 2 were like 51$ea the 2 lower were 42$ea and I bought new crush washers 20$ , this was money well spent safety is NEVER something to scrimp on !!!!!

 

I've always used compressed air to extract pistons but I do realize there are dangers. Keep fingers out of the line of fire, cushion the piston with rags. When replacing the valve stems on a tubeless rim, save one for this purpose.

 

Getting my order ready now. I had to give the bleeding a try didn't work out so hot brake lever felt great but didn't do a whole lot of braking. Replacing pretty much everything

 

Great move bravo.... I had a stiff brake lever but brake action was not good , the hoses were stamped 81 and I do not think the calipers were ever apart so it was time . Good luck

 

Use a a large syringe (find at tractor supply, farm supply or eBay) and a piece of clear tubing to reverse bleed the brakes. Took me 15 minutes after a complete rebuild.

Put a piece of rubber or something similar between the caliper sides an use air to push out the pistons. Put a piece of wood or folded rubber in front of the piston before beginning to prevent damage to piston or caliper.

 

I have a large air compressor , 120 psi did not budge piston. Grease gun pushed piston right out.

 

I had to do the same thing they were seriously stuck

 

Mine were not completely stuck and since I was completely rebuilding them I doused them with brake fluid and actually pushed them all the way in before applying the air pressure is short bursts. I'm surprised a grease gun will apply more that 120 psi, but it is a safe way to remove them if you don't mind the clean up. Also, boiling the calipers for about 15 minutes will loosen up all the goo and make removal easy.

 

Grease doesn't compress as much as air, so it acts as a hydraulic ram instead of as a spring (and lubricates as it pushes). A typical manual grease gun can develop anywhere from 2,000 to 15,000 PSI, depending on the size of the gun and how the internals are put together.

 

Good point. If 15,000 psi doesn't do it it's time to abandon the caliper!

 

This is why construction equipment, ie bulldozer or excavator, uses hydraulics instead of pneumatics. Flashbacks to high school shop class. Robotics class without a single microchip! How old am I?

 

Since you brought it up, I wonder what's the age of the oldest XJ rider? 71 here and plan to ride until I drop!

 

+1.

Gary H.

 

Dude you could be my dad... he is 72 on his 3rd Goldwing he has had more bikes than I can remember all Hondas 350, 550, several 750, 450 ...I've only had 7 bikes but tend to keep them for extended amounts of time.