Front brakes don't work!

[jvsimmons]

This has been an ongoing saga since I purchased my 1983 S3 88 County diesel. I have replaced everything except the hard lines from the MC and the steel lines to each wheel. I have a good firm pedal when braking....no spongyness or softness. Drove it yesterday and when I got home I checked each wheel to see if they were hot. Found that the rear wheels were good and hot......the fronts were cold, it was as if they were not working.. My conclusion is that the front brakes are not working. I've had the system bled by a shop and the shoe adjustments are as far out as they will go on the rears and in a couple of notches on the front. Since the drums and shoes are new there is still a bit of drag. I have removed the shuttle valve so that it cannot be the problem. I have removed the front drums and watched the new wheel cylinders move as the brake pedal is displaced.....what i don't know is how they respond in actual road braking.....apparently not very well. I don't know what to do next. I have read many forum post and the only input that may be relevant is the bleeding of the MC. I don't know if the shop I took it too knew to do that. They did a bad job with some other repairs so I will not take it back to them. I've checked that the brakes lines from the MC go to the appropriate wheels ( front port to front wheels; rear port to rear wheels - the MC is a 1 1/16 bore) . I don't know how to bleed the MC without having to do the rest of the system.

Does anyone in this forum know what I should do? Or how to check to see if there is air in the front part of the MC preventing full hydraulic pressure to the front wheels.....and then how to fix that. I am really frustrated with this problem.....other issues I have been able to work my way thru them but this is a stumper. Thanks in advance

[charles1943]

HOW LONG WAS THE DRIVE U SPOKE ABOUT??? I suggest U try some REALLY HARD braking....for maybe 5-10 minutes to give those fronts every possible chance of 'doing their thing'. They may not be bedded in yet. SOmetimes we get on BOTH the brake and the accelerator pedal at the same time, at ~50 MPH for maybe 10 minutes or miles & that helps to burn in the shoes more quickly {& give them a REAL chance 2 heat up)

[jvsimmons]

Wish I could get to 50mph! Anyway, the front and rear drums and shoes were replaced at the same time. So why are the rears working and not the front.....seems the fronts should "bed in" before the rears since they are suppose to provide the majority of the braking force. I live on a 1 mile hill so going down that should have bedded the shoes/drums. The temperature difference between the front and rear is significant....burn your fingers on the rears and won't melt ice on the fronts. Suppose I could try what you suggest but I anticipate that the rears will get hotter and nothing will happen with the fronts.

[charles1943]

We've found that some of the shoes are dimensionally incorrect [in a very careful comparison] not sure that's what u're up against. Have u removed the front drums 2 see what kind of 'print' the shoes display. R they the 10 or the 11" shoes & drums? How many wheel cylinders/wheel in the front? Do u have any fluid leaks up front??? [brake fluid or 90 wt.?]

[jvsimmons]

Before installing the drums and shoes I checked to see how the shoes "sat" against the drum. All was good. The fronts have two wheel cylinders, the drums are 11 inch; rears one wheel cylinder with 10 inch drums. No leaks anywhere. I have not taken off the front drums to see if there is a "print". I will do that tomorrow. I still suspect that the bozos at the shop I took it to didn't properly bleed the master cylinder.

[roverp480]

Is there not anywhere near you that can test the brakes to see what retardation you are getting on each wheel? Here in the UK, I would take it to the Local MOT testing station where its annual roadworthiness test is done and they could supply a reading for each wheel. You say the fronts are not working, if you brake hard you should be able to lock up all wheels on a dry flat surface . I just wonder if your master cylinder isn't working properly. I am not 100% certain but if the piston for the front brakes has bottomed out & not returning under its spring pressure, it will not create any pressure to front brakes although you would have longer pedal travel .

[jvsimmons]

There is no way I could lock up the wheels no matter how hard I push on the pedal. What would cause the front piston to bottom out? Bad spring? Air in the cylinder? Contamination? Other? If the piston for the rear was working properly ( which it seems to be doing) then the rear brakes would engage when the pedal is depressed and one would not sense a soft pedal because of the failure of the front piston/brakes - am I right on this? Unlike in the UK there are not many shops where I live that are familiar with Series LRs, And some LR shops even refuse to work on them - they want high turn over and don't want repair bays taken up waiting for parts. Seems my only option is to fix it myself. The shop that replaced the MC did say that they had to return the first MC they purchased as it failed.....they eventually tried three MCs before giving my S3 back to me saying it was fixed. Which it isn't.. They must have purchased the MCs from either RN or Atlantic British. Maybe I should just purchase another MC and see if that fixes the problem but the cost is steep and if there is a solution without making that purchase then I need to find that out first.

[jvsimmons]

There is no way I could lock up the wheels no matter how hard I push on the pedal.   What would cause the front piston to bottom out?  Bad spring? Air in the cylinder? Contamination?  Other?  If the piston for the rear was working properly ( which it seems to be doing) then the rear brakes would engage when the pedal is depressed and one would not sense a soft pedal because of the failure of the front piston/brakes - am I right on this?   Unlike in the UK there are not many shops where I live that are familiar with Series LRs, And some LR shops even refuse to work on them -  they want high turn over and don't want repair bays taken up waiting for parts.  Seems my only option is to fix it myself.  The shop that replaced the MC did say that they had to return the first MC they purchased as it failed.....they eventually tried three MCs before giving my S3 back to me saying it was fixed.  Which it isn't..  They must have purchased the MCs from either RN or Atlantic British.  Maybe I should just purchase another MC and see if that fixes the problem but the cost is steep and if there is a solution without making that purchase then I need to find that out first.

[charles1943]

1 way 2 tell if your frons brakes are working is to clamp off the [2] flex hoses and see if the brake function changes at all,at speed. You could also clamp off the rear flex hose and see how that affects things. You might observe the front wheels under hard barking and see if they show any slowing of the front wheels.

[jvsimmons]

That approach would certainly be interesting. Would want to first try the clamps on the front brakes......clamping the rear sounds a little dicey.....if the fronts indeed don't work I could wear out the heal of my shoe trying to stop!

[jvsimmons]

Following the recommendation in an earlier reply I removed the front right drum. Found that the new shoes were showing wear marks, in the middle and on the ends of the shoes. The marks were not uneven side to side. I then had my wife press the brake pedal to check the travel of the pistons in the wheel cylinders. There was not a lot of travel....more in the top wheel cylinder ( front most shoe).....the bottom cylinder did not move until I put pressure on the front shoe to keep it from moving ( it still moved but had resistance from my hand). Neither the top or bottom cylinder moved alot. These are new wheel cylinders. Should there be a lot of piston travel without the drum in place? I've pretty well described the symptoms. What is wrong and what needs to be fixed so that the brakes work well enough to skid the tires if I needed to.

[roverp480]

The cylinders do not have to move much to operate the brakes so I would not be concerned . They do operate which confirms they work. You will not get full braking until the shoes are bedded in and you get full contact over the whole of the shoes . Just keep using it and operate the brakes frequently in short bursts to bed them in. I remember back in the 1960's when I had a S2 diesel I overhauled the brakes, new shoes, cylinders etc and it took about a thousand miles to get really good brakes. . Girling who made the original brakes for Land Rover used to grind the linings after fitting to the shoes, to make them match the drum diameter. Which make of shoes are they, as I have heard of the wrong grade of linings being fitted? I am not sure if this helps, picture from Girling Bulletin on pedal travel . As yours is a later S3, 11" front brakes, the 109" figures would be more representative.

[jvsimmons]

Thanks. I feel a bit more comfortable about the brakes. I still am puzzled by why the rear brakes get HOT while the fronts are cold after driving the S3. The adjusters are as "in" as they will go on front and back. I bought the shoes from Rimmer Brothers ( sorry RN but they were cheaper even with shipping and got here quickly). One box was Britparts the other Ferodo. I don't remember which brand went where ( front or back). Why two brands - had to do with availability during covid.

Item 6 in the Girling Bulletin refers to a Figure 3. Can you forward that to me? My pedal travel is good.....and is firm.

I will continue to drive and "bed" the shoes. Hope the braking improves and that this is the end of the saga

[vlad_d]

@JVSsimmons, you said some stuff that rang a bell for me. You said you have 11” drums. You said you had a PDWL valve, (which you removed) and you talked about plumbing the MC “the right way” with front pipe going to front brakes, etc.

I just did my brake system, and was all over the parts manual, so it’s fresh for me. That PDWL/Shuttle valve was for a 2 line system, and Vacuum Booster(I don’t know if your MC is backed by a Vacuum Booster/Servo, but guessing so). That points me to a year range between 73-85. Around 80, they switched piping on the MC…they flipped it. So the larger volume line is on the “farthest back” plug post 1980…and on the “front” pre 1980.

Look at these two MC’s closely:
1980+ type (front brake larger line on front pipe - yellow cap)

https://www.roversnorth.com/parts/pli859_brake_master_cylinder_late_series_iii

I put this one in.

1971-1979 type (front brake larger line on rear pipe - red cap)

https://www.roversnorth.com/parts/plc762_master_cylinder_dual_power_109

1969-1980 SWB/88 type.

https://www.roversnorth.com/parts/plc454_master_cylinder_dual_power_88

Find out which one you have. They look similar, and interchange (even if the parts guide says they are not to be used for different years…they fit. It’s the swapping of lines that makes the recommendation not to use them off years). Look closely at yours. In the aftermarket, the difference is:
* The brassy body sticks out past the plastic reservoir (1980+)
* The more squarish reservoirs (1980+)
* The larger volume line will have a 7/16 DIM fitting on it (so you can’t normally swap lines by mistake) even though the line is the same thickness. You’ll see the “7/16” on the plastic cap of new ones.

Like I said, because they totally fit, there’s nothing to stop a mechanic from putting the 1980+ one on there. I did, and it works great. But the lines swapped. If someone ran new lines, they wouldn’t know. So check that, because 11” drums have larger wheel cylinders and the front fork in a dual line system needs more volume. So, I suspect you might have all that volume going to your rear brakes instead, pressing them hard and getting them hot while the front are barely engaged.

For what it’s worth, I have a brand new system(100% new components, including PDWL, all new pipes) and mine doesn’t lock up either. Stops great. But…it’s drums. So I say that because I think your rear brakes wouldn’t lock up due to over pressure. Drums just don’t normally do that. They’re not like disks.

[jvsimmons]

There has been more developments and I'm afraid this saga will continue. First, the new developments. Another Series owner stopped by last night and he and I discussed the brake issue... and went for short drive ( a little over two miles), during which we tested the brakes with some hard braking. When we got parked back in the garage the rear wheel was again HOT and the fronts cold. We then first looked at the adjuster - shoes were as "loose" as could be adjusted. Then we removed the drum - it came off easily with very little resistence. Ummm, then why is the wheel so HOT. With the drum of the axel was still difficult to turn ( emergency brake was not engaged) We then began to suspect that the wheel bearing may be too tight - both wheels felt hot; so could wheel bearings on both sides be too tight? Since, a half shaft was replaced by the shop I took it too earlier they may not have adjusted the bearings correctly or just ignored the adjustments, OR did not check or replace fluid in the differential. Now I have somethings to check: fluid level, bearing adjustments, emergency brake adjustment. Will get to all this this weekend.
Now for the comments about the MC and plumbing. Thank you for the input. Unfortunately I do not know if the shop I took it to installed the correct MC. With the info you sent I will check. Obviously the colored plugs are no longer there as a guide. Without knowing which MC they installed I don't know if the plumbing as it now is, is correct or not. And to make sure I understand what you said: on Series 3 after 1980 the MC port for the front brakes should be at the rear of the MC...correct? I will look at the MC using the info you sent. Guess I could switch the lines where the shuttle valve use to be and see what I get. The Series owner that visited didn't think we drove far enough or brakes hard enough to heat up the rear wheels like we found. This saga may have multiple levels of problems to sort out: brake line plumbing, correct MC, wheel bearings, fluid levels. I appreciate the time and effort that all have contributed to helping me diagnose and correct the problems.