New owner, brake and temp. gauge questions.

[tosoutherncars]

Just be sure to hone the cylinder, if you're rebuilding... if it has worn the cylinder wall smooth, a new seal won't have anything to seal against.

 

[highhilleer]

Just be sure to hone the cylinder, if you're rebuilding... if it has worn the cylinder wall smooth, a new seal won't have anything to seal against.

Sounds like a good idea! Any idea what size the cylinder is? The hones come in different sizes. The local parts store has one that handles from 3/4 to 2 1/4 inch bores.

 

[tosoutherncars]

It's close to 3/4", but I'm not sure. The earlier cars are 3/4" and 7/8"...

 

[highhilleer]

Well I got the master cylinder apart, hopefully the rebuild kit will be at the house when I get home. I messed with the nylon washer for a long time trying to follow the instructions in the repair manual to remove it. Sliding the cylinder in and out a thousand times like the book says just didn't do any good. Searched this forum and found the "burn out" method. However there was nothing in the instructions about keeping hands away from the melting nylon so I've done the research - <span style="color: #FF0000">do not</span> let molten nylon drip onto your skin - you will curse and there will be residual pain. :frown:
I'm not sure the rebuild will work as there is some pitting/roughness where in the area where the cylinder transitions from the large diameter to the smaller one. Also an Am-Pro 3/4" cylinder hone will not reach to the bottom of the small cylinder as the attachment point where the three arms for the hone attach to the too is too large. I'll hone the lower portion of the cylinder with some emery cloth wrapped around a dowel.

Thanks for the help. Hopefully tomorrow I can post how the brake job turned out.

 

[highhilleer]

Bummer!!! Spent the weekend on the brakes doing:
rebuild MC
rebuild both calipers
replace front and rear hoses
replace disc pads
inspect rear brakes - pleaty of material on shoes, no leaks of cylinders
adjust rear brakes
adjust parking brakes

bleed and rebleed the system

All to no avail - I could tell backing the car out of the garage that the brakes just do not grip. A short trip through the neighborhood confirmed scarry brakes. A lot of pedal pressure will get the car to stop and there is no pulling to one side. The stroke of the pedal seems ok and the pedal is firm at the end of the stroke without bottoming out. It just takes too much force on the pedal and too much distance to stop. Haven't found any leaks and the MC stays full.

I'm thinking the pressure differential valve (shuttle) may be the problem as spritenut suggested. The brake light is not lit, but it doesn't come on with the parking brake engaged, so I think I have another problem with the light. I tested the continuity at the back of the pressure differential switch and got a signal. I believe this means the switch has been activated. I haven't been able to get the switch to center by bleeding so I'll pull it tonight and see what is up.

I would appreciate any comments/suggestions
Thanks
John

 

[JPSmit]

when you rebuilt the MC, did you take off and clean the two fittings on the side (where the actual brake lines go) I was stunned how much crud there was in mine when I rebuilt the MC

 

[jlaird]

There is some trick to get the shuttle to center, and I'll be darned if I remember what someone said.

 

[highhilleer]

when you rebuilt the MC, did you take off and clean the two fittings on the side (where the actual brake lines go) I was stunned how much crud there was in mine when I rebuilt the MC

Didn't remove the ports, but I used a bench bleeder kit and flushed the master cylinder until there was all traces of gunk were gone. There was a lot of crud in the bowles of the MC. I do not think the MC is my immediate problem but I suspect there will be a MC replacement or resleeve in my future.

 

[sparkydave]

Bummer!!! Spent the weekend on the brakes doing:
rebuild MC
rebuild both calipers
replace front and rear hoses
replace disc pads
inspect rear brakes - pleaty of material on shoes, no leaks of cylinders
adjust rear brakes
adjust parking brakes

bleed and rebleed the system

All to no avail - I could tell backing the car out of the garage that the brakes just do not grip. A short trip through the neighborhood confirmed scarry brakes. A lot of pedal pressure will get the car to stop and there is no pulling to one side. The stroke of the pedal seems ok and the pedal is firm at the end of the stroke without bottoming out. It just takes too much force on the pedal and too much distance to stop. Haven't found any leaks and the MC stays full.

I'm thinking the pressure differential valve (shuttle) may be the problem as spritenut suggested. The brake light is not lit, but it doesn't come on with the parking brake engaged, so I think I have another problem with the light. I tested the continuity at the back of the pressure differential switch and got a signal. I believe this means the switch has been activated. I haven't been able to get the switch to center by bleeding so I'll pull it tonight and see what is up.

I would appreciate any comments/suggestions
Thanks
John

Hi John, FYI, to center the PDWA valve on a 1500, I have found the service manuals were incorrect, at least it was for mine. I had to unscrew the switch from the body to get the shuttle to center. No, I don't know why that is the case, but when I took mine apart, I found the shuttle has a flat ridge that the switch rides on, and once the shuttle moves, the switch pushrod latches in place and keeps the shuttle from moving. If your seals are in good shape, you can unscrew the switch from the body without leaking. Also there are springs on the shuttle that will center it once you do that, so you don't need to follow the service manual procedure. I can only assume there was more than one style of PDWA that was in use, because the pictures of the PDWA shuttle in my service manual show a groove in the center where the switch sits, and mine has a ridge. Hope this helps!

 

[highhilleer]

Hi John, FYI, to center the PDWA valve on a 1500, I have found the service manuals were incorrect, at least it was for mine. I had to unscrew the switch from the body to get the shuttle to center. No, I don't know why that is the case, but when I took mine apart, I found the shuttle has a flat ridge that the switch rides on, and once the shuttle moves, the switch pushrod latches in place and keeps the shuttle from moving. If your seals are in good shape, you can unscrew the switch from the body without leaking. Also there are springs on the shuttle that will center it once you do that, so you don't need to follow the service manual procedure. I can only assume there was more than one style of PDWA that was in use, because the pictures of the PDWA shuttle in my service manual show a groove in the center where the switch sits, and mine has a ridge. Hope this helps!

Man this really helps, <span style="color: #FF0000"><span style="font-weight: bold">THANKS</span></span>!!! I hate it when the manuals are wrong as I do not have the experience with these cars to know what is right. May be we should start a thread or list of corrections to the manual.

I've heard there are different style switches. It sounds like the guts of the one you have is like this, photo posted by CK 1500:

The repair manual shows something like this.

___________________________________________________________________________________

So if I understand the situation correctly, the repair will follow one of three paths:

<span style="font-weight: bold">Optimistic</span>
Remove the switch, do not find brake fluid in the switch chamber, centering spring does it's job, replace the switch, happy motoring.

<span style="font-weight: bold">Pessimistic </span>
Remove the switch, find fluid, remove the PDWA, clean up and replace O rings, replace, happy motoring

<span style="font-weight: bold">Highest probability</span>
Remove the switch, find fluid, remove PDWA, clean up, find pitting, send the unit to Apple or White Post for a resleeve, replace, continue working on "little things" for the rest of my life.

 

[highhilleer]

SparkyDave nailed it!! I removed the PDWA switch and while screwing it out there was a click. I bench tested the switch and it was good. Just for fun I pumped the brakes a couple of times and checked the switch chamber for fluid. Since it was dry, I reinstalled the switch, hooked up the wires and went for a test drive.

I am very happy and relieved to report the brakes are working about as good as I could expect. With enough pedal force the tires will even lock up.

Today must be a good karma day as the temperature gauge started working again. The incents I was burning to find that happy place in the garage must have restored the smoke in the wires.

Thanks to all those who provided input!

 

[jlaird]

All's well that ends well.

 

[walshja]

you ever get your brakes straightened out?