81 special rear brake

[dpotter58]

I changed the pads, made sure to have kept plenty of fluid in the master cylinder, blead the caliper and i still don't have it. the front has plenty of grab. Is there something I'm missing? I know the pedle controlls both the rear and the left front, is there a technique to adjust the amount the rear grabs relative to the front?

[TopCatGr58]

Hey there Dpotter,

From my understanding the proportioning valve at the rear master cylinder controls that, and I think it's set/calibrated to NOT apply as much pressure to the rear as the front, to prevent locking it up! I don't think it's adjustable?

SO...you might be able to remove the valve, and connect the line directly to the MC, that way you would have equal pressures to front and rear? Or, separate that line, and have it only going to the rear, and connect the other front one to the front MC?
T.C.

[81xsproject]

I thought it was the XJ's that had the brake combo plus valve..?

[dpotter58]

Thanks TC. I thought there was supposed to be like 60% rear 40% front out of the valve.
While the bike stops, now it feels like the pedal goes down more than it did before. May just be paranoia...I'm going to look at the adjustment to the linkage later today and make sure it's set right.

[John]

Hey dpotter

The 81LH has a linked brake system like the XJ, right? A few guys here, myself included, use a reverse bleeding method. We bleed the system by forcing the fluid from the caliper up to the m/c, and chasing the air out through the reservior. I happen to have a tool designed to do this on cars and trucks, and it can also do hydraulic clutches also. Anyway, you can chase all of the old fluid out of the system this way, and never run the risk of the reservior running dry. You will have to remove the old fluid from the reservior frequently, as the reservior will fill quickly, and you don't want to have that crap spilled onto the paint. I have read here that some guys use an oil squirt can to force the fluid up into the m/c. Another method will be using a 'Mighty Vac" vacuum pump to suck the fluid from the m/c down to the caliper. Keep an eye on the fluid level in the m/c when using this method. You don't want to suck it dry. One last choice will be to remove the caliper from the bracket and let it rest lower than the m/c, open the bleeder, and let it gravity bleed for a while.
Hey, how did those pipes turn out?

[dpotter58]

First of all, the pipes are great. Sound nice and look a whole lot better than the flat black spray painted pipes I was running. They made a world of difference in the appearance.Thanks again.
On the brakes, I had bought an oil cooler and used blue permatex as a gasket between the engine and the piece the filter goes on to. I checked it for leaks the next day, took it for a test run and when I hit the brakes to slow down, I didn't stop like I usually do. Got home and found more oil on the bike than in it. The blue crap has been replaced with red. I figured the pads were shot so I changed them. I had a hard time getting the caliper back on the rotor so I used a c-clamp to squeeze it in a little. I opened the bleed screw before tightening and shut it before releasing the clamp.
when I got everything back together, I bled them and got just a small amount of air out. The pedal still does not feel like it did before changing the pads. It seems to have more travel in it. I have not checked the linkage yet, but it would seem to me that putting on thicker pads ( the old ones were fairly worn) would have the oposite effect.