411 brake problems

[Kevin H]

Peter,
Try these people NORTHWEST CLASSIC SPARES

kevin

[PEU186F]

I must apologise, I find I put out a piece of misinformation regarding track rod ends earlier in this correspondence. I said that the 407s to 410s used 5 RH and one LH track rod ends. This is incorrect, the parts list lists 5 LH and one RH, the latter on the centre rod.

The Amsteer part numbers are AM13LH and AM13RH respectively.

But just to confuse matters, at one point, before I discovered Amsteer, BCS were unable to supply me with a LH track rod end and insisted that the entire near side track rod be replaced. I surmise, but cannot readily check, that this used RH ends, so there MAY be other cars out there where the 5 to 1 ratio no longer applies.

Amsteers AM182LH and AM182RH, which they list for the 411, are presumably specific to the centre rod on the 411 and possibly the later cars.

Roger Morrall

[peter dowdle]

Rodger I can see no possible use for the right hand thread unit as the centre rod ends are of a larger diameter taper . Amsteer dont have a listing on the center rods . Thankfully mine are in good nick.

[peter dowdle]

Can Any One Tell Me How To Remove The Brake Master Cylinder On My 411. Seemed Easy I Unbolted The Cylinder And Disconnected The Fluid Lines, So Far So Good.

The Next Step Was To Remove The Pin That Holds The Yoke To The Pedal Assembly. With Difficulty I Removed The Split Pin And Pushed The Pin Out Of The Yoke As Far As It Would Go. Big Problem There Isnt Enough Room To Remove The Pin, Thus I Cannot Remove The Yoke.

Any Ideas On Where To Go From Here ?

[peter dowdle]

I finally managed from sources in the UK and Australia to obtain a master cylinder repair kit for my series 2 411 Bristol. I employed a professional experience mechanic to fit the kit , ensuring it went back together correctly.
After much fiddling I had everything back in place. The pedal came good after some bleeding. Job completed after a short test drive.
Next day I drove the 35 Km to have the wheel alignment done. Upon opening the bonnet I found the front brake tank overflowing and the rear one nearly empty. ENOUGH
From the advice given on this forum I purchase a mid 70s Range Rover new cylinder.
Fitting was fairly easy. Parts required
1/ A plate with 2 studs fitted to back of firewall
2/ lengthened push rod ( extra 15mm )
3/ Two new brake lines to extend to boosters.
All fitted together easily

BRAKES ARE FINE

[Claude]

I have read through the postings on the 411 Master Cylinder, but I would appreciate some clarification and assistance.

Initial symptoms: 411-S1 has stiff rear brakes.

1. Problem One: The flex hose to the rear axle was completely blocked. Replaced it with H892 found at Sterling Brakes in Auckland (last one). Now fluid flows to rear, but brakes still stiff.
2. Problem Two (maybe) I removed the rear calipers (Girling 12/3HP). They seemed in relatively good shape (they were rebuilt in 2004, but not driven since), but needed a bit of surface cleaning on the top of the pistons due to sitting. Two trips to the brake shop and $200 later, I put them back on car, jacked up both rear wheels, removed wheels, started the engine, the wheels would no turn when in Drive at idle. Applying some power would turn, but clearly the pads were gripping.
3. With the engine still running and still in gear, I loosened bleed valve on the caliper, fluid came out, immediately the brakes released.

This points to something upstream keeping pressure on. Options include:

• Master Cylinder needs to be removed, inspected, probably rebuilt
• Hose on the Master Cylinder is partially blocked (works on braking, not on release)
• Servo needs attention of some sort
• There is a pressure relief valve that I don't know about (is there one?)

1. If it is the Master Cylinder, it is unclear how one removes it. One comment about an impossible to remove split pin. Is this something I may encounter? I would appreciate a step-by-step removal instructions that I can then summarise for others (the problem with forums is having to read through all of the dialogue to find the core information necessary to solve the problem).
   .
   A. If it is removed, what is it? How can I find out how to rebuild it. What is the manufacturer (Girling/Lockheed?), what generic part number, what other vehicles use the same master cylinder.
   B. Alternatively, what more readily available equivalent is available? I read about Land Rover, sounds like a more difficult procedure, and I read one comment about using a modern master cylinder. What would be the best alternative retrofit?
   .
2. With the hose, it looks easy - get another one. I'll do that when the shops open.
   .
3. With the servo, if I disconnect the vacuum and the servo is the problem, does it release the brakes, or do I need to make a bypass line and unbolt the in/out brake line nuts to eliminate the servo as a suspect?
   .
4. And finally, am I missing anything else?

My hunch is that the rubber hose at the Master Cylinder is partially blocked... it will work when foot pressure is applied, but closes down when back pressure wants to release the pads.

Finally, BODA asked if they could use my postings of the "shadetree mechanic" steps taken, so I have been documenting the findings for future owners in a way that eliminates the back-and-forth, but provides the helpful directions for those of us too far from a qualified repair shop. Clarity in answers will be appreciated by future Bristol custodians (Bristols can last forever, it's the current owners who come and go).

[Kevin H]

Originally Posted by Claude

My hunch is that the rubber hose at the Master Cylinder is partially blocked...

Must be different to the 411 S5 - there's no rubber hose connecting to the master cylinder on my car...

According to the 411 Owners Manual the master cylinder should be a Girling product.

It does sound very similar to the issue Peter Dowdle had.

EDIT/PS: Claude, please post a photo of the master cylinder

[PEU186F]

Claude

Too many issues one after the other can seem daunting but the best approach is to follow a logical elimination path.

Releasing the pressure after the servo allows the brakes to come off, so it's either the servo or the master cylinder that is holding them on, now that you've eliminated the brake line between the servo and the callipers.

So release any pressure between the master cylinder and the servo, simply by loosening a connection point.

If the brakes don't then come off it is the servo that's the problem, if they do then it's the master cylinder, or possibly the brake line between the master cylinder and the servo. To eliminate the latter try loosening a connection point at each end of that brake line

If it's the servo it's a case of rebuild or replace, I'd be pretty certain that there must be someone in NZ who rebuilds them, if of course you can find them.

If it's the master cylinder do just check that the brake pedal is free to return fully before you attack it.

My knowledge of V8 brakes stops at the 410 which uses twin Girling master cylinders, callipers and connectors but Lockheed servos (Lockheed 4258-405). I believe that the 411 is similar apart from the single master cylinder.

Roger