240 soft brakes - please help!
 

If you out your foot on the break and press down then start the engine, it’s normal for the pedal to sink further until it firms up again - that’s a sign the servo is working.

If you release the pedal then press it again, it shouldn’t go down as far as before you lifted it.

Assuming the pedal stays hard when you press it down, I’m not sure you have a problem with air that needs bleeding. If it is at all spongy, then there’s still trapped air. That can happen when the calipers are fitted on the wrong side of the car such that fluid enters at the top and the bleed nipple’s at the bottom, below the fluid inlet. Bleed it as much as you like, it will stay spongy.

Hi,

I had this problem for years with my 240 and it turned out to be the anti-squeal shims. Take them out, you don't need them...

Thanks

Because the system has been drained (best not to unless unavoidable) the spider block will need bleeding

Thanks to all of you for input - very useful

A couple of local journeys later and the brakes are certainly biting better - in other words they are bedding-in just fine. The problem is to get that bite (and we're not talking unduly heavy braking or a load greater than two adults) I need to use 3 or 4 inches of travel on the pedal and at one point when I needed a bit more brake quite a bit more. That's not right to me...

So, Dai, what's a spider block? Please!

Cheers all

Nick

Spider Block
 

On the near-side chassis leg, if you follow the pipes from the master cylinder, you'll find a piece of kit with 8 pipes coming out of it. This is the "spider block" or "octopus" and it splits the fluid among the various calipers.

There is also a switch on the unit, made of nylon so very fragile. This switch needs to be cracked open to let the valve centre itself; you may(probably will) need to re-bleed the brakes themselves afterwards if any air gets into the system.

I don't think a 1991 car has the sliding valve inside.
Earlier cars did, and the valve was triggered to warn of a pressure difference between the two braking circuits.
Later cars dispensed with this, and instead the warning light was simply triggered by a fluid level detector on the master cylinder reservoir.Check if there is actually an electrical connection to the octopus.

I'm not sure when the change-over happened, but none of my cars from 1990 onwards had the sliding valve.
You can bleed the octopus thing by slackening a pipe coupling on each circuit and gently expelling some fluid, like bleeding a house radiator.

I've had your symptoms once, and it was when I'd fitted the kind of front brake pads that have a massive chamfer. I was alarmed when they arrived that they had such a reduced surface area, and they took so long to bed in that I replaced them with the ordinary non-chamfered kind.

My '89 has it...

Thanks all for continuing thoughts. An update:

So garage #2 had a go at bleeding the system and now it's worse! Dai kindly spoke to them directly particularly regarding bleeding the distribution valve (aka spider block/valve). They'll have another go at it next week and see how things are after that

I have no experience at all of hydraulics so altho I understand the principles, I don't want to get directly involved in something as important as brakes

Keep you posted. Meantime I'm keeping extra distance and only driving locally!

Thanks all, Nick

I've heard it said that the pressure-limiting valves in the pipe run to the rear brakes can cause problems if the system has been completely emptied. They are at the highest point of the run so air bubbles can stick there.
The advice is to jack the car up as high as possible at the back, or park facing downhill.

My standard advice at this point is never to drain the entire system at once. Seal off each section, bench bleed the components, and bleed air out of the joints as you re-connect them.