Front brakes don't work!

[jvsimmons]

vlad_d, Attached is photo of my MC. It appears to be the correct MC. It has a 1 1/16 inch bore. The rear port does indeed have a 7/16 fitting. The front fitting is larger with a 13mm fitting. So, is the "larger volume line" on the rear port even though the fitting on the front is larger?

[jimrr]

the only thing to keep the shoes from retracting is either fluid is not making it back into the master resevour. (tipping valve or shuttle, distance (clearance) in the master cylinder rod assy or maybe weak return spring on the shoes?

[charles1943]

Quick note: U cannot switch the pipes 'cuz your pipes have different thread sizes [just so that can't happen!!] If your hub/wheel bearings got "that hot" they would lock up solid. Or screech like a banshee!!!! A LITTLE hot and U'r lucky. Superhot and most of that end of town will know about it. And U will 4 sure!!!! Been there!

[vlad_d]

Yours looks like mine, the later one.
Here’s how I hooked mine up. If you zoom in the pic you can see it going down to the PDWL/Shuttle valve.
My PDWL valve is plumbed: front side to front brakes, back half to back brakes.
On mine, it goes:
MC rear to front circuit of brakes
MC front to real circuit of brakes

Hope this helps. I’m going to see if I can find something in the green bible that says that. I hate to give brakes advice without reference. Hang tight…

[vlad_d]

Agreed. You’d have to have a double flare tool and put a new flare fitting one, which I did when making up new lines.

The reason I suggested this is…with old cars, you can’t guarantee what’s on there came that way from the factory. Any mechanic in the last 50 years could have changed it. So…you might not be able to trust the flare fitting on there. I mean pretty safe…but if you have phantom issues, this might be something to check.

[jvsimmons]

Thanks vlad_d. Thought about buying a complete brake line kit from the UK. RN doesn't stock the kit for my 83. Then the issue of fitting sizes and thread came up and with the new MC and shuttle valve ( and not knowing the size and thread) I may just use the old fittings and flare new pipes. I did check the wheel bearings and they looked good.

Saturday morning I went for a short drive - after correcting the plumbing from the MC to the direct-to-wheels line fittings ( shuttle valve has been removed for the time being). Still had a fairly decent pedal. When I got home I checked the temperature at each wheel. Three were warm as one would expect. The 4th ( right rear ) was hot. Jacked it up - checked adjustment of the shoes - pulled the drum ( came off easily) - inspected the shoes and was surprised by what I found. The rear shoe had horizontal ribbing - see photo. They ridges are not high but one can still feel them when rubbing finger across the shoe. The front shoe was smooth. I cannot come up with a plausible cause and cure for this finding. Anyone got any ideas?

[charles1943]

My sense of what I see is that the best way to address what you mention would B 2 use some 80-grit sandpaper and using circular strokes, dress the surface until the ridges disappear. What would concern me more than the ridges would B that the shoe might B a mismatch to its counterpart on the opposite side of that axle, causing the brakes to pull to 1 side.

[charles1943]

1 ?: have U mike'd your drums, and what sizes are they? This wants 2 B done with a vernier caliper 4 accuracy!

[charles1943]

AND I'd B concerned if Rimmer shipped U 3 sets of shoes of type "A" and 1 of type "B". Maybe they didn't but it looks that way. Is that the case?

[vlad_d]

I would get some new components an/or get some machining at the local brake shop or machine shop.

* Get a brake kit for about $50 that includes new pads, cylinders, and springs. Link below.
* Take your drums to a local shop and ask if they can turn them. My local PepBoys or smaller shop would charge $8 to turn them…and you’d get a perfect surface to mate with those new pads. Yes, you can just get by with some sand paper, if they aren’t gouged or out-of-round. But, $8 is cheap insurance. It will rule out any wonky drums.
* In fact, you could get these parts to a local brake shop that isn’t a major chain(they hire 25 year olds who’ve never seen drum brakes and won’t touch them)…and have the shop wrestle with them. You can find the parts, since the shops have no idea where to get Series parts.

I hate to send links from someone other than our hosts, but here’s the $50 kit:

https://www.johncraddockltd.co.uk/da6043-swb-rear-brake-kit-up-to-1980-shoes-cylinders-and-springs.html

The photo you sent looks pretty rusty. I wouldn’t bother trying to make all that work. You’re looking at $50 of “consumable” parts. Nothing precious there to save for future generations…just get some new pads, springs and cylinders.

New drums are about $50 each. I have an extra one that I put a slight ridge in when I bent a shoe trying to leverage it on and it scratched a bit. DM me if you want it. I would give it for free, just send shipping or trade for something and you can have it turned for $8 locallly.

In the end, it’s your brakes. I’d hate to drive on rusted brakes when it’s only $50 of parts. I know people like their “patina” on these old Rovers…but…you know…you wouldn’t be doing yourself any favors driving on crap brakes. Let the fenders be rusty for the Instagram photos…but the brakes should be solid, right?

[jvsimmons]

Vlad_d:

I had finally got some decent front brakes. The PDWL valve was bypassed. Then a couple of weeks ago I decided that it would be good to have the PDWL put back in the system for safety. It was a new PDWL. I have had nothing but problems since - and again cannot get the front brakes to work. Put in a new MC, then bled - still no front brakes. I pulled the drums to check to see if the wheel cylinders were working. Found the upper on the left wheel was and the other three were not moving at all - they are new wheel cylinders. If I crack the bleed screws fluid comes out. One possible cause could be wrong plumbing at the PDWL valve. My question to you today is: is there a front and back to the PDWL valve so that one side allows more pressure or are they equal as straight pass throughs ( until there is unequal pressure). As it is now plumbed the line from the rear of the MC goes to the PDWL and the outgoing line goes to the front brakes as makes sense but could I have the incoming and outgoing lines attached to the wrong end of the PDWL? I made a plug to keep the piston in the middle of the cylinder as I bled the brakes. Another possibility that I have not pursued is that one of the long lines from the PDWL is clogged or partially clogged. I did check the "T" and it seemed to be good. Or could the front brake side of the MC have a problem and is not putting sufficient pressure. Maybe I should bench bleed the MC again. The rear brakes work great so the problem is on the front side of the system.
Thank you for your previous post on the dual line / PDWL system used on late model S3s. They are well done.

[biffidum]

Your master cylinder may be pooched - rubber seal on shaft at the end that feeds the front brakes. R&R or rebuild. Cheap enough to buy.

[vlad_d]

Hey Jim,
* It’s been a while since I was elbow deep in that project. But I seem to remember the flare heads on the lines are different sizes…and the inputs on the Shuttle valve(PDWL) front-back are different thread sizes. I think this is to prevent you from installing it backwards if you remove it. But no guarantees if you’re running your own lines and putting your flare heads on yourself.
* If you have the reservoire that looks like mine(squarish), then the line closest to the Booster/Firewall is the largest volume one, and should be plumbed to the front brakes.
* Get yourself some bleeder screws with a ball valve in them, or do the trick with some vacuum hose and a little throw-away clear container of clean brake fluid, so it doesn’t suck air in when you bleed the brakes. You might have to set it up and open the bleeder screw and be over by the shuttle valve to force it one way or another. The valve should move pretty easy back and forth. Just take the bottom access port off and use a flat screwdriver to push it forward or back - to open each circuit. Or just hold it centered as someone in the car floors the brake pedal.
* Once open, there should be nothing stopping the flow. As long as you don’t suck air bubbles in, you should be able to flush the lines out with clean fluid. If you get pressure out of the lines, you can rule out the MC. Holding the shuttle valve centered should rule that out. The only thing left would be the wheel cylinders themselves.
* But I’ll tell ya - if there’s even a little air in the line, those shuttle valves will do their job and shut that side off. And no amount of pushing will let fluid go to that side. That’s why people get frustrated with them and remove them. But they are actually performing their job well! That’s exactly what you want to happen on the road with a leak! I remember spending 2 weekends convinced something was broken. It was just that shuttle valve returning to the closed position when I tried to bleed the rear wheels. It’s almost like you have to have 3 people - one to pump the pedal, one to open the bleeder screw and close it immediately, and one to hold the shuttle valve centered. You can actually get by leaving the bleeder screw open slightly if you have the vacuum hose into clean fluid setup, because it can’t suck back much. So that means you can be on the shuttle valve, and back to only needing 2 people. Once you get “most” of the air out of the system, the shuttle valve won’t be so finicky, and you can go back over to each bleeder screw and be quicker about closing it off for a final flush.
* Long way to describe it, but I hope this helps somebody.