Bleeding brakes

[Morris]

[Splat]

Yup. That’s the one.

[Westfield 129]

I use a $45 pressure bleeder from "Motive Power" to bleed the brakes. This quickly bleeds the brakes, removes all the air form the lines using air pressure at the reservoir to force fluid through the individual lines. It never misses, doesn't require any pumping and does a perfect job, single handed, every F'n time. I also have a Vacula vacuum bleeder, that also does a good job, and I still use it, but for the 11, and just about any other car, the Motive Power bleeder is best. It also makes flushing the brake system easy, but remember to keep the reservoir topped (though the system will auto fill the reservoir if so desired).

But... For years, I had a problem with inconsistent braking, using the standard single master cylinder. It was even keeping me from really enjoying the car in the canyons as I was always second guessing the brake response. And then... I read an article in one of the UK magazines that included an article about the Noble M400, which I was representing here in the US.
The article complained about the brake feel... "Like stepping on a dead animal, squishy with hard bits"... YES! That described my 11s brake problem precisely! I was thinking that there was a mismatch between the tandem master cylinder that the factory included with the kits, replacing the old style Girling single cylinder. So, what to do... I talked to the nice people down the road at Wilwood, the brake caliper and component manufacturer. They recommended a new pedal quadrant, but that didn't make sense to me. So, I decided that the problem might be pad "knock back", the pads being hammered back into the caliper by disc runout. I measured the runout at the rotors, but didn't find anything unusual. Still, THAT had to be the problem.

I replaced the ball wheel bearings with a $180 set of Timken tapered wheel bearings, with the shims to properly adjust the hub torque (yes, they are torqued into position, and not torqued by "feel"). PROBLEM SOLVED. What I got immediately was stable, predictable braking, with a solid pedal every time.
Then, I went to one of my friend's cars with the same silly brake feel problem, with the tandem master installed. I installed the taper wheel bearings, and again, perfection. The ball bearings don't hold their tolerances well, and after a couple of hundred miles, the runout returns. Maybe this is OK on a Spridget, but on the W11, well... Not so good.

If you want to get a good brake bleed, every time, get the Motive Power pressure bleeder (the standard European cap fits both the single and tandem master cylinders) and install a set of the Timken wheel bearings, and properly shim them. Speedwell Engineering in California has the kits. Worth every penny. I am sure that there must be someone in the UK that also has the same parts.

[Morris]

All interesting points, thank you Jan.

I'm beginning to think that my issue isn't related to air in the system so I'll be having a closer look once I've completed some other jobs.

I did try an 'Easybleed' type system, but after having the cap blow off the M/C a couple of times and causing a terrible mess I reverted back to the traditional pedal pushing method.

Hopefully once I get onto the road the feel should be ok as I've already fitted tapered roller bearings.

[Westfield 129]

You can also try a vacuum brake bleeder that attaches to the bleeder at the brake. The best are driven by your compressor. They also work quite well, though they appear to draw air bubbles into the bleed line. Not a problem, but it looks as though you are not bleeding the brakes fully. These bleeders are also useful for removing fluid from small reservoirs.

The best is still a pressure bleeder, and probably the least expensive way to single handed bleed brakes without pumping, and do a proper job.

[jonclancy]

Hi All,

Changed my brake fluid using my pressure bleeder, and everything seemed to be fine for the drive home. Car left on drive for a few weeks (as usual). Moving my fleet around, I had no brakes at all for the first press! Second firmed up fine. Left the car a while and jumped in to test having attended to a small part of the huge list of jobs to be done before CLM. Brake pedal was firm (ish). I was thinking about getting a seal kit for my MC, but having trouble identifying the part.

L 32 L

LBBEHM022A/3.0 stamped on the alloy tag plate. Google useless and no tie-wrap ID, same a Morris. Not got the moolah for a new MC, and if all’s good, I’ll put it down to an air bubble finding its way out after bleeding. I will do the seals sometime, though. The kit isn’t expensive.

Your thoughts appreciated.

[jonclancy]

Inconclusive Googling has led me to write to AP Racing requesting the current 13/16” equivalent. Both Caterham and Westfield do a standard MC, which is just under £300. The AP Racing MC has a 60/40 bias designed in, and is factory-shimmed. But, ouch, it’s expensive!

I’m coming to the conclusion that older MC get obsoleted, and, as AP have done, the seal kits become unobtanium too. Depending on the position of the bypass ports in the cylinder, the right “looking” seal kit might not be what you need.

My brakes work, but are lacklustre. I may have to just grit my teeth and shell out.

Cheers

[jonclancy]

Dropped by to visit Jan for a very enjoyable few hours yesterday. As it happens, he has two of the original Westfield-supplied MC on the shelf. We chatted about the options, including fitting a pair of MC and a balance bar. I had the set-up on my SEiW back in the day. Our cars are punched for this option ex-factory. Certainly a cheaper, and more flexible set up. The MC are not too expensive, and remote reservoirs are an option.

I think I’d like the speed and similarity (and proven out of the box results) of the AP Racing unit. But the cost..

To add something to the debate, AP make OEM stuff. AP Racing appears to be their offshoot. Might give them a call on Tuesday anyway, to see what the score is regarding availability etc, so will ask. That’ll be why our parts numbers don’t match up with the AP Racing ones.

Jan’s parts numbers on the tag matched mine, the batch numbers being L 22 A and L 20 E. The following are cast into the underside of the cylinder:

LB 06 BZ 005BD 10FC

Lots of detail here for the Google Bots to scour. Might be of use to someone in the future.

[Morris]

I dream of fitting a remote reservoir, given the difficulty I have in filling the reservoir in its current position without making a mess.

[jonclancy]

Could be an option. I have found a MC in stock, but the price is waaaaay out of reach at £538.

https://www.a-pp.com/Categories/Braking ... 27-2PRM100



Some more info culled from various sources for the bots:

>>>

After a bit of snooping around today, it turns out I already have a 13/16" or 0.8125 master cylinder. The AP part number on the body is CP3627-101C. The internet doesn't bring up much from this part number. A few threads on Westfield and Marcos forums.

>>>

reading through the other forums the body is the CP3627-101C and the complete unit with reservoir is CP4627-2PRM100 . The Marcus forum even points to a stockist. I've sent them an email and will see what comes back.

Picked up one interesting fact which have never twigged before which i'll put down in case someone else finds it useful in future, the ports are marked P & S

P is the prime circuit which is connected to the front

S is the secondary circuit which is connected to the rears.

on pressing the pedal the prime circuit operates first and then after closing a clearance gap the Secondary circuit operates.