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Randy Roberson
Grand Master
Username: wascator

Post Number: 359
Registered: 5-2009
Posted on Sunday, 22 March, 2015 - 10:32:   Edit PostDelete PostView Post/Check IP

Hi,all, I'm catching up. The weather last weekend allowed me to take SRH9391 out for another shakedown-test run. You might recall I took most of 2014 rebuilding the brake pumps and height control valves. Well, I'm sailing along the local 4-lane divided at 70-75 mph; suddenly the front brake warning lamp illuminated. Oops; not a car in sight, hills and plenty of room; test the brakes: aha! plenty of brakes, no other symptoms, so I slink carefully back home.
The fluid level seemed a little low in the front compartment; no major leaks evident. I can't tell for sure if the front pump is doing its thing. Shut down and worry.
This afternoon, indoor work only because of the rain, nearly every day recently, so I check underneath. The warning lamp harness came with female spade terminals and the newer switches have a bullet connection, so there is a short jumper-conversion wire. It is bare on the terminals and touching/grounding periodically,which explains the occasional flash of the rear warning lamp. I am hoping the activation of the front warning lamp is a similar situation, because I started the car and the fluid level in the front reservoir dropped significantly. This tells me the pump is pumping.
Advice or comments welcome. I cannot see the front apparatus without getting her on ramps or a lift, so further investigation will have to wait a bit. Question: is it correct to fill the reservoir to a level between the marks with the engine running?
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Brian Vogel
Grand Master
Username: guyslp

Post Number: 1250
Registered: 6-2009
Posted on Sunday, 22 March, 2015 - 10:51:   Edit PostDelete PostView Post/Check IP

Randy,

My understanding is that one should fill the reservoirs to the full mark after the car has been started and has run, unladen, for 4 minutes or so.

If you do the brake pump test when the car is turned off your fluid levels should rise to well above the full marks when you've exhausted the accumulators.

Brian
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Bob UK
Unregistered guest
Posted From: 94.197.121.92
Posted on Monday, 23 March, 2015 - 10:57:   Edit PostDelete PostView Post/Check IP

Connect gauge to ACV nipple and check the cut in and out pressure.

Disconnect wire to pressure switch. Connect continuity tester between switch terminal and earth. Note pressure at which switch goes open.

If all correct then check wiring to switch in engine compartment. Might be worth replacing the two wires entirely. They go to engine loom plug. Press the tang down with small screw driver and the wire complete with brass terminal will come out. The correct colours are on the web. AES good site.

If the pumps work then they work and are not prone to suddenly not working.

The dot level should be checked after at least 4 mins. The instructions should be by the sight glasses.

The level is not critical keep between full and min level.

I keep mine on full because I might as well.

My money's on dodgy wiring that has been cooked by engine heat.

(Message approved by david_gore)
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gordon le feuvre
Frequent User
Username: triumph

Post Number: 65
Registered: 7-2012
Posted on Monday, 23 March, 2015 - 21:20:   Edit PostDelete PostView Post/Check IP

What Brian says is the easy simple test. I used to pump brake pedal for at least 1/2 minute. If ignition on BUT engine not running 2 things should happen. I. the system lights should come on after 30-40 pumps of pedal. normally left hand light (No.1)first. sometimes rh light would come on then go off again. Bouncing rear of car should empty pressure in rams and bring back on light.
Even if lights do not come on (switch problems) after bit of practice you can tell when no pressure in systems as pedal loses slight spongyness and application takes on more metalic noise when applied. As Brian says this will put fluid back in reservoirs. Start engine and watch as pressure builds. This should be apparent by levels dropping to between(as Bob says) max and min. Sometimes it is really hard to see fluid level dropping. Also DO take care when running engine as it is SO easy to knock gear lever. (Really should take out gearbox isolator from fuse board)
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Bob UK
Unregistered guest
Posted From: 94.197.121.117
Posted on Tuesday, 24 March, 2015 - 06:31:   Edit PostDelete PostView Post/Check IP

The reason No1 comes on first is that it operates 8 pistons
whereas No2 does 4 pistons.

Pumping the
system down also purges any air in the ACVs.

After working on any brake system on any car I give the brakes a good work out on the road.

The gauge can be connected to a caliper bleed nipple. Which will show the pressure at the caliper.

Note the front caliper nipples on my car 1974 year. Have 10mm fine bleed nipples not 3/8 unf.

Not sure about the following
The psi at the calipers should be 500psi with a 40lb load on the pedal. Or was it 80lb not sure.

Drive car at 70mph and slam the brakes on. The front wheels should lock.

Also 10 mph in reverse.

I you are windy about using the brakes hard at high speed, Start at 30mph and work up.

This will give you more confidence on the brakes.

Set tyre psi to 32psi

(Message approved by david_gore)
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Bob UK
Unregistered guest
Posted From: 94.197.121.117
Posted on Tuesday, 24 March, 2015 - 06:58:   Edit PostDelete PostView Post/Check IP

Gordon mentions spongeness of the pedal

The brake valves are held shut by a spring and HYDRAULIC PRESSURE. The hydraulic pressure can be felt. If the system has no pressure then if the brakes are applied the pedal will push back as the system charges.

gearbox relay thingy, don't forget or take rear wheels off.
When running engine with no one on the driver's seat.

When checking the dot level, run engine for 4 mins, then turn engine off and immediately check dot level. The level is not critical.

(Message approved by david_gore)