Series 3 servo / master cylinder operation?

Here's a photo - its from my 101, but the only available replacement parts are s3 (hence posting in the s3 section of the forum) -




Pressing the brake peddle gives a squelchy noise from the servo, which has a hole in it close to the union with the master cylinder.

My understanding is that the servo should be 'dry' (as in no fluids involved) and is there to either give resistance or return the master cylinder? (im unsure about that / which one!)

Anyhow, for the purpose of my job, id say that the master cylinder has failed, and the fluid has rotted the servo, right?

So, do them both, and i should be fine?



(the brake fluid reservoir is dry, and, obviously, there are no brakes...)

Im 250 miles from the vehical, so my intention is to buy the parts for a weekends visit, hence remote diagnostics.


I reckon i need -

master cylinder (converted s3 unit)
101 Land Rover Brake Master Cylinder

servo
101 Land Rover Servo (Replacement)

mounting kit for servo (to rotate the servo for fittment in the 101)
101 Land Rover Servo Conversion

Certainly looks like that servo's been dealing with brake fluid - it's done the usual great job as paint stripper. Yes, the servo should be dry inside. It's really just a vac chamber "helping your foot".

Not sure what brake fluid would do to the servo. When my master went drenching everything the servo seemed happy enough after the master was changed.

might just need a seal, not a whole new cylinder, but given the circumstances, I would take a whole cylinder, too far to go to find you haven't brought enough stuff.

might be worth taking a couple of spare wheel cylinders with you too.

my understanding of the servo is as toomany2cv's said it is to assist with braking, especially at higher speeds. More brake for less pedal pressure.

blue beasty said:

Not sure what brake fluid would do to the servo. When my master went drenching everything the servo seemed happy enough after the master was changed.

Click to expand...

You'd like to hope that the diaphragm inside the servo was brake-fluid resistant, but by the look of the outside, there's been fluid leaking all over it for quite a while. A clean and re-paint might sort it, but I'd be looking very carefully to see whether it was more than surface rust. From reading the bit about the "hole" (can we just see it to the far side of the master?), I'd say that it's already rotting.

For the cost of a servo and the conversion plate, versus the ball-ache if you find out that it really is knackered, it can't be too hard a call.

julianf said:

Here's a photo - its from my 101, but the only available replacement parts are s3 (hence posting in the s3 section of the forum) -


Pressing the brake peddle gives a squelchy noise from the servo, which has a hole in it close to the union with the master cylinder.

My understanding is that the servo should be 'dry' (as in no fluids involved) and is there to either give resistance or return the master cylinder? (im unsure about that / which one!)

Anyhow, for the purpose of my job, id say that the master cylinder has failed, and the fluid has rotted the servo, right?

So, do them both, and i should be fine?



(the brake fluid reservoir is dry, and, obviously, there are no brakes...)

Im 250 miles from the vehical, so my intention is to buy the parts for a weekends visit, hence remote diagnostics.


I reckon i need -

master cylinder (converted s3 unit)
101 Land Rover Brake Master Cylinder

servo
101 Land Rover Servo (Replacement)

mounting kit for servo (to rotate the servo for fittment in the 101)
101 Land Rover Servo Conversion

Click to expand...

The servo just uses vacuum to push a little harder on the master than you can with your foot.

Whether or not that has been rotted by fluid, or just by salt or damp air, it looks like it is tired, and could use replacement.

Looks like you have all the right parts there. My only concern would be that at those prices, the quality may not be fantastic. They don't really say where the bits are from, as far as I saw.

Best of luck with it!

Post this in the 101 part of the site. U may get more advice.

Again, its not a query specific to 101s - just happens to be on one! : )

More people are into s3 than 101s also, and, as im going to be using all s3 parts, i figure Ill get more knowledge here.

The servo is rusted through, that's for sure, so I will just get all the bits. I'll look into parts for the wheels also - thankyou.