Seca 750 Front brakes sticking

The previous owner said he rebuilt the calipers and they grab tight, just don't want to let go after you squeeze the lever. The lever is very firm, no give at all and the front wheel doesn't want to free-wheel. Is it a master cylinder problem? Maybe things not hooked up right in the calipers?

 

I think the first thing I'd check is the cable - is it rusty, gunked up, or ?? Does the cable move freely in the housing? You didn't say anything about it, so I'd start with the easy stuff first...

 

Mine came with the same exact problem. Rebuilding the calipers took care of the problem. Getting the pistons out was fun. From some other threads I had read, I replaced the bleeder with a grease nipple and pumped away...... I liked the safety factor of using the grease versus compressed air. Purchased the rebuild kit from Len, took my time, and all is well and good.

 

scotty - yeah the po didn't do it right. You're going to have to take them apart again and pull the pistons. Like Smoooth said, using a grease nipple in place of the bleeder is the safest way to go. Once you get the pistons out your going to have to polish the piston AND the piston bore so that the piston travels smoothly inside the bore. Also, very important, you MUST clean the groove that the seal fits in on the piston. If you don't get all the old caked on gunk out of the groove the seal is not going to fit correctly and it will not allow the piston to operate as it should.

 

I would say definitely the calipers. My Seca 650 had the same problem. One caliper was seized but I rebuilt them both. Attatched is a picture of the seized one. I replaced the piston as it was unusable (any pits or dings at all and it will leak) and a light honing of the caliper and finish the cleanup with some 1000 steel wool and all is good again. Of course be sure to replace the seals and boots.

I did the seized one first and left the other one on the bike so I just used the brake lever to remove the piston. Be sure to keep an eye on the fluid level while you do this. The other piston came out just by pulling on it.

If you need pistons I got mine here: http://www.hvccycle.com/

 

Scrape all the Foreign Matter out of the Caliper Main Seal Channel.
The Channel needs to be scraped down to bare aluminum.
After scraping; flush with Brake Kleen.

Upon reassembly, lube the Seal, Channel, Cylinder and Piston with clean, fresh Brake Fluid.

Clean and refinish any Rods and Pins that "Travel" or other Parts Travel upon.
Lube traveling parts with Synthetic Waterproof Grease.

 

a problem with both calipers is very nearly ALWAYS not a problem with the calipers but instead a problem with the master cylinder.

as suggested. Rebuild it. it will fix it.

 

The symptoms of a Master Cylinder needing to be overhauled and rebuilt are;

Working the Brake Lever does not develop Hydraulic Pressure and the System is free of Air Bubbles.

Failure of the Master Cylinder to "Pump-down" Fluid when a Bleeder is open.

A "Geyser" of Brake Fluid shoots-up in the Fluid Reservoir indicating that the Main Hydraulic Seal is leaking-by, ... and the Pressure of the Rear Cylinder on the Brake Fluid forces it back-up through the Master Cylinder Fluid Replenishment Orifice.

Weak or no Fluid Pressure upon attempting to Bench Bleed the Master.

 

Regardless; ALL of the rubber parts in the brake system need to be replaced: Master cylinder seals, caliper seals, hoses. Rebuild the M/C and both calipers, and replace the hoses (assuming they're probably original.) The factory recommended lifespan of the M/C and caliper seals was TWO years; the lines, four years.

NO SHORTCUTS ON BRAKES. It's a 130mph bike!