Did I waste my money?

[Robbie693]

Thanks all for your replys.

Sean, I didn't see your bit about the chassis tank - probably good as I'd have been completely confused! And I would be sobbing in my beer, if I had a beer

Anyway, mentioning tick over as you did, the car does change idle speed when I pump the pedal - it did this before which is partly why I replaced the servo...

The boost 'hiss' lasts for two or three pedal presses after engine switch off and I can the feel the pedal resistance returning as I pump.

[Foxie]

Robbie,

while you're in there, check the condition of the rubber elbow connecting the manifold nipple to the metal vacuum pipe. I traced what I thought was a servo problem to this elbow. It looked perfect on the outside, but was a complete goo inside from exposure to fuel. It was collapsing completely under vacuum and isolating the servo.

Sean Murray

[Robbie693]

Thanks Sean. I'm going to check this later

[alaric]

Hi.

Concerned that I might make a bigger whally of myself I have stayed away, but did revise how a servo works by rooting out my old Mini workshop manual; as the coopers had a remote servo. I've attached a scan of the page. I just thought it was really neat.

When I replaced my brake pipes it took me some time to get the joints all sealing properly - not wanting to strip threads etc. So, if you pressurised the system for some time, would some fluid eventually appear from a joint? Can you jam something against the brake pedal to hold it down, so that fluid comes out rather than air in, and leave it for a few hours? It may be worth just checking the joints - I'm always nervous of damaging them?

Sean.

[Robbie693]

Hi Sean,

Thanks for that - very interesting.

It's rare for a manual to show that much information about servo's, usually it's "...it's broken... buy a new one"!

Don't be so hard on yourself - your post and the one from the other Sean put me onto checking the vacuum side of things. I'll report back when I get chance to check it.

Cheers

[Robbie693]

Well I fitted new hose from the manfold to the cross-over pipe but the problem persists.

I did have some slight weeping from the pipe connections to the servo though.

Ordered a new caliper but I'm confused by the Metric or Imperial options. The last one I bought was metric - the Robinshaw Ross book says that mine (December 1972) should be so but the pipe connection didn't fit so I had a new one made up.

Classicar say that the mountings were different on each and when I told them the metric caliper fitted my car they said that the metric will fit both but not the imperial???

How does that work?

[patrics]

Hi Robbie,
It?s always difficult to diagnose without actually seeing the problem but:

1. Press the brake pedal once and with a heavy load. Does it sink? If no go to Test 2 if yes then you have a hydraulic leak. Do not pump the pedal during any of the tests.

2. Press the pedal very slowly. Does it sink? If the answer was no to Test 1 but yes now then the master cylinder is probably leaking.

3. If it was leaking from Test 1 then check every single connection including those by the diff, the hoses, caliper connections and bleed screws ? use your finger to wipe each joint you will easily see if there is a leak.

4. If you can not find a leak then you will have to check calipers. Clamp off the hose to each caliper in turn and repeat Test 1. If the pedal doesn?t sink during one of these tests then the problem is with the clamped caliper. If the pedal sinks during all tests then the booster will probably have an internal leak.

5. If the pedal was sinking during test 2 then you will have to take the cylinder apart and check for debris on the front seal and any scoring.

6. If you have a hydraulic leak then it will leak with or without the engine running as long as the hydraulic pressure generated is the same for both.

7. Not associated with your sinking pedal but I suppose the easiest way to check for any vacuum leaks would be to pull and block off the connection at the manifold and see if the idle has changed.

8. Fitting new parts doesn?t mean they are good, especially items like hydraulic servos.

9. You should be able to easily bleed any basic system like this by normal methods and without to much fluid.

10. New calipers will feel more compressible than old seized ones.

11. Metric and imperial type 16 calipers are only interchangeable if you change the hydraulic fitting to suit. An imperial fitting will physically go into a metric fitting but that doesn?t mean it fits, a metric nut will not go into an imperial fitting. Also the Girling / Ford M16 had different mounting centres compared to other Girling Type 16 calipers.

Regards
Steve

[Robbie693]

Thanks Steve, great reply.

I'll print it out and go through the checks systematically.


When you say the Calipers had different mounting centres, does that mean that they are not interchangeable?

The last caliper I fitted was a metric one and the pipe union didn't fit but did fit the mounting plate.

This time I've ordered an imperial caliper, assuming that the unions are all imperial. Will this one fit the mounting plate also?

[patrics]

Hi Robbie,

The calipers with different mounting centres are not interchangeable. The Lotus types are 3.5" centres and the Ford type 3.25".
An imperial type 16 should fit your car but get one which matches the other side so that brake pads, connections, pad retaining pins and piston boots are all the same.

Regards
Steve