'77 2500M Brake issue and PDWA switch question
Discussion
Hello All,
I'm so close to getting my 2500M to the point where it's roadworthy. I solved my horn not working issue, my fans not working issue, rebuilt the carbs, set the valves and synced the carbs. It starts and runs happily and cool now and I thought I was done, only to find my front wheels do not rotate freely. I can rotate them with my hands, even rotate the hubs with the tires off but not without some effort -- the brake pads are flush against the discs and causing some friction, see below.
Previously the PDWA/Handbrake light was always lit. I disconnected both switches and the light went out. With this brake issue I assumed the PDWA had set. I removed the PDWA switch to check. Everything looked happy in the PDWA body with the piston right where it should be with no brake fluid in there. BTW, the greasiness you see around the PDWA body is just penetrant. I anticipated having to remove it.
So, I put my continuity tester on the two posts of the switch and got continuity, whether the button was pushed in or not. I then thought the swith was the culprit, but looking into the switch cavity where the connection posts are, I can see they are connected together so of course it would show continuity. I don't get it.
Can someone please explain how this switch works internally or how I can test it? I thought the button being pushed in by the piston moving left or right completed the connection between the two posts.
Is it possible the wrong brake pads were installed or is the level of friction I described OK?
Thanks for your diagnosis and advice!
John
UPDATE -- I just tested the PDWA switch for continuity again, this time with one lead on the metal switch body (where the threads are) and the other on one of the posts. It showed continuity when the button was pressed. So, the purpose of the switch is to connect to earth through the switch body, through the PDWA body, to the frame to which the PDWA is bolted, rather than completing a connection between the two posts? Strange. Why then have two wires going to the switch? I must be missing something. In any case, with the switch "switching" and the PDWA piston where it should be, then I assume the PDWA is OK. Would you agree?
I'm so close to getting my 2500M to the point where it's roadworthy. I solved my horn not working issue, my fans not working issue, rebuilt the carbs, set the valves and synced the carbs. It starts and runs happily and cool now and I thought I was done, only to find my front wheels do not rotate freely. I can rotate them with my hands, even rotate the hubs with the tires off but not without some effort -- the brake pads are flush against the discs and causing some friction, see below.
Previously the PDWA/Handbrake light was always lit. I disconnected both switches and the light went out. With this brake issue I assumed the PDWA had set. I removed the PDWA switch to check. Everything looked happy in the PDWA body with the piston right where it should be with no brake fluid in there. BTW, the greasiness you see around the PDWA body is just penetrant. I anticipated having to remove it.
So, I put my continuity tester on the two posts of the switch and got continuity, whether the button was pushed in or not. I then thought the swith was the culprit, but looking into the switch cavity where the connection posts are, I can see they are connected together so of course it would show continuity. I don't get it.
Can someone please explain how this switch works internally or how I can test it? I thought the button being pushed in by the piston moving left or right completed the connection between the two posts.
Is it possible the wrong brake pads were installed or is the level of friction I described OK?
Thanks for your diagnosis and advice!
John
UPDATE -- I just tested the PDWA switch for continuity again, this time with one lead on the metal switch body (where the threads are) and the other on one of the posts. It showed continuity when the button was pressed. So, the purpose of the switch is to connect to earth through the switch body, through the PDWA body, to the frame to which the PDWA is bolted, rather than completing a connection between the two posts? Strange. Why then have two wires going to the switch? I must be missing something. In any case, with the switch "switching" and the PDWA piston where it should be, then I assume the PDWA is OK. Would you agree?
Edited by jastx on Thursday 6th December 03:37
Can't really see the state of your calipers (pic does not want to enlarge)but if the pads are flush to the discs, the pistons in the calipers could be the culprits ? Mine were corroded up to 1/2 'depth' and after refurb (broke the calipers, ref 'buckeyed triumph) and redone them completely/new slaves in the rears > problem solved. Please report !
Haven't we got contact concerning the 'proto' 3000S for sale ? (you disapproved of it....)
Enlargement do work now, the pistons look too much out, the rubber retainers look shod aswell, and as a consequence the discs/wheels are 'stuck' Think you should investigate this first of all, you'll probably find the pistons are corroded (when ordering new, make sure you got the right type 16B/16PB)Fairly simple and inexpensive jobee, but a bit of labour (bring on saturday.....)
Enlargement do work now, the pistons look too much out, the rubber retainers look shod aswell, and as a consequence the discs/wheels are 'stuck' Think you should investigate this first of all, you'll probably find the pistons are corroded (when ordering new, make sure you got the right type 16B/16PB)Fairly simple and inexpensive jobee, but a bit of labour (bring on saturday.....)
Good news, was an easy fix. After speaking with a local British car specialist and fellow member of the local Triumph club chapter here in Dallas, Texas, I removed the brake pads and pushed the pistons back into the caliper with channel lock pliers (brake reservoir top removed and watched, caliper protected from the channel locks). They slid in easily, thank goodness. Put everything back in and pumped the brake to hard pedal. Now, when released the wheels turn freely with the pads floating above the disc as they are supposed to. Must have stuck from inactivity.
I should finally be on the road with my car Sunday after reassembling a few other bits. No more inactivity. Yahoo!
Thanks for the advice.
John
I should finally be on the road with my car Sunday after reassembling a few other bits. No more inactivity. Yahoo!
Thanks for the advice.
John
Best thing you can do with the PWDA is throw it in a skip. It is a nasty piece of 1960,s BL tatt. If you can bleed the brakes without it putting the light on, and 95% of the ones I,ve done don,t then its not working and wont work if you get a brake circuit loss. Put the split circuit braking in the master cylinder.
Frank,
Thanks for asking. My sticking brake disc situation has been resolved. I now understand the PDWA, its switch and its wiring. My BRAKE warning light is on but it's not the PDWA switch, it's the handbrake warning light switch -- need to replace it. This a learning experience for me so it's been taking some time researching systems and parts, tracing issues on the car, gaining understanding, then doing the work. Just set the valves. Distributor/timing settings tonight, hopefully. Final carb adjustments and I should be, finally, ready to roll. It's been fun but after a year and half of ownership I want the car on the road. After enjoying it on the road and fitting new shocks & springs, the next phase will be detailing -- cleaning everything and restoring the finish to those areas with deterioration. This car has less than 5,000 miles and has spent its life inside but still, with age, has some light surface rust here and there on pulleys, certain engine parts, the brake servo, etc.
Even put my polished Wolfrace wheels on this past weekend (labels added too) in place of the T-Slots with surface corrosion. Here it is, amost ready:
John
Thanks for asking. My sticking brake disc situation has been resolved. I now understand the PDWA, its switch and its wiring. My BRAKE warning light is on but it's not the PDWA switch, it's the handbrake warning light switch -- need to replace it. This a learning experience for me so it's been taking some time researching systems and parts, tracing issues on the car, gaining understanding, then doing the work. Just set the valves. Distributor/timing settings tonight, hopefully. Final carb adjustments and I should be, finally, ready to roll. It's been fun but after a year and half of ownership I want the car on the road. After enjoying it on the road and fitting new shocks & springs, the next phase will be detailing -- cleaning everything and restoring the finish to those areas with deterioration. This car has less than 5,000 miles and has spent its life inside but still, with age, has some light surface rust here and there on pulleys, certain engine parts, the brake servo, etc.
Even put my polished Wolfrace wheels on this past weekend (labels added too) in place of the T-Slots with surface corrosion. Here it is, amost ready:
John
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