How do you adjust the brake pedal??

[C.Costine]

Is your caliper centered over your disc?

qVwZBa1tQf2ZSkbM9UdNaQ.jpg

[bajaroadster]

will be rounding up a feeler gauge today. Left most of my tools in the U.S. when we moved down here. Process of elimination continues. Anybody know if the 510 master cylinder is available thru Autozone? its the only major parts store down here in the Baja. Getting parts from the vendors on this site is not currently an option as shipping across the border is cost prohibitive. I generally have parts shipped to friends that are traveling down here but with the border closed that option is off the table for now. I'll check the wiki for part numbers and visit the local store. (SIGH) All this time on my hands and I cant drive the roadster. And the weather is PERFECT for driving right now down here.

[Gregs672000]

You mentioned installing shims for the master. I've always thought these were there in order to put the pedal and master "in line" so the rod pushes in a centered way in the bore, but I may be mistaken (I know the shims come in upper and lower halves and varied in thickness).

How much free play do you now have in your pedal? Push the pedal by hand while watching the action on the rod etc and make sure the pedal itself is not maintaining pressure by pushing on the rod. You should be able to move the pedal back and forth some without it pushing on the rod, i.e. not pushing the master cylinder. I think you mentioned that the rod is threaded. Have you tried pulling out the pin that connects the rod to the pedal (the spring usually attaches to the pin), pushing down the rod so you clear the pedal arm and turning the fitting on the end of the rod in (there may be a lock nut that needs to loosened) to create more slack when you refit the pedal to the rod.

OK, I just reread your original post and it says the rod is adjusted all the way out... I think that's your problem. The rears may not lock up but they are a different system that probably requires a bit more travel to push the brake shoes against the drum... the front disc system provides about 70% or so of your braking and tend to be very close to the disc. It may be the heat being generated by constantly applied brakes make them lock up over several miles... everything expands.

[Linda]

The brake pedal should be at the same height as the clutch pedal, as I recall
The brake rod should be pretty close in length to the original Nissan rod, or just swap them out if you have a 510 and try that.
On my 510 master the rod had to be cut to make it work.
If you don’t have the Nissan rod maybe someone can send you that to try.
Good luck
Linda

[bajaroadster]

Greg, I shimmed the master in an attempt to move the rod further away from the brake pedal to gain more travel thinking the brake pedal might be keeping the piston partially engaged. I had no more adjustment on the rod so I thought I would try shimming the master. The brake pedal backward travel was being limited by hitting on the mount for the brake light switch. After shimming the master, the pedal now has a slight gap between it and the switch mount. I just went out after reading your post and removed the return spring on the pedal to check the amount of play. It is very minimal, but the rod is fully extended as far as I can tell. I don't believe that the master is a 510 version as there are no adapters present, unless the PO swaped the receiver hardware. Although the brake pedal is a bit higher than the clutch pedal. On a side note, I think we met years ago when I was visiting some friends In Tacoma. I was driving a red 68 2000 with the stock wheels painted to match the car color.

[Gregs672000]

You said " the rod is fully extended"... do you mean that the linkage (the part the pin goes through) is screwed all the way out toward the pedal? If so, you need to screw it inward so you shorten the rod. With the linkage fully extended you are pushing on the master cylinder.

[bajaroadster]

Greg, meant to convey that the rod adjustment could not go any further toward the master because the rod was hitting the back of the brake pedal lever.
Disassembled the driver side yesterday and sanded down the sides of the pads as suggested by CKTRAP. He was correct that they were very tight. Will do the passenger side today. Also bought some feeler gauges to see if calipers are centered on rotor or if I need shimming. Ill keep plugging away until I figure this out.

[Gregs672000]

Ha, got it. A picture is worth a thousand words as they Say! Keep on it!

[bajaroadster]

Disassembled The passenger side today to sand the brake discs slightly as they were very snug and I thought that it might be contributing to my ongoing problem. One of the metal brake lines has a rounded fitting and needs to be replaced. The tech wiki mentions a long and a short fitting on each line so I measured to make note of the fittings when looking for a replacement line to bend. Both fittings are the same length. Each fitting is 5/8 " long. Do I have the wrong lines on the car or am I misreading something in the tech wiki?

[C.Costine]

Yes there are two different sized fittings. The reach is different. If you remove them you will see which is which.

[bajaroadster]

C.Costine, The reach? I have the line off the car and couldn't see any difference in the fittings at each end so I measured them. They are the same length. Is the wiki referring to different lengths of the fittings on each end of one hard line, or maybe different lengths of the fittings from one line to the second line? The line I have off is the one that goes from the bottom of the outboard caliper to the connection at the rubber brakeline. Again , the fittings on both ends of that hardline seem to be identical.

[C.Costine]

The reach is basically the length of the threaded section. I made up new lines for my '67 and the kit had two different fittings with different reaches. When I assembled them I had one on each side that wouldn't tighten the tube. I had to remake them using the long fitting. I believe that it was at the fitting where it ties into the flex tube.

[bajaroadster]

Well, sounds like i'm going to have fun trying to find a generic line at the local parts store that will work. (Sigh) Anybody planning on traveling to Mexico that wants to bring me some parts? No? Im buying all the tequila.

[bajaroadster]

A quick update to thank all that gave suggestions and advice. I seem to have resolved the problem and the car is back on the road. Purchased a brake line flaring tool and was able to salvage the old brake line with the bungled fitting. Checked that the pads were centered correctly with a feeler guage as C.Costine suggested. Sanded the new brake pads slightly as suggested by CKTRAP to allow free travel. That step seemed to do the trick. Test drive yesterday saw no drag of pads and no overheating or seizing. Many thanks all. Saved my bacon once again. The offer still stands that I buy the tequila whenever a member makes it down to the Baja. Google Loreto B.C.S. See ya after the lockdown.

[bajaroadster]

Seems I spoke to soon. Took the car on a longer drive today and the symptoms returned. (Caliper piston(s) locking in applied position and brake pads and rotors overheating.) If I continue driving, frt brakes completely lock up. I have tried all suggestions offered by our great members and at my wits end at this point. The only other thing I can think to try is rebuilding the master cylinder. I have a kit but have not installed it yet because the master was supposedly rebuilt just before I purchased the car. I know the seller as honest and knowlegable and have no reason to doubt him on this. Any other thoughts on solutions to try before I tackle the master cylinder?