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SE5a rebuild/rolling restoration - no brakes today

Posted: Wed Apr 03, 2019 4:13 pm
by Jpwill7675
Thanks for the recent advice. I have now replaced the diff oil after removing part of the Watts linkage to get to the refill plug. I took the car for a 30 mile shake down yesterday. The car ran slightly roughly but without any major issue, leaks or drama. This morning I went to take the car for another run but nearly crashed into the gates - no brakes at all.

The pedal goes down to the floor without much resistance and pumping the brakes had no effect. Running the engine made no difference either. The vacuum hose from the servo to the engine looks intact. I have checked the system and can no see no obvious sign of leakage at the master cylinder, servo or lines to the calipers. The brake master cylinder was fitted two years ago and the car has only done about 1200 miles since then. I wonder if it is a coincidence or if I have knocked something whilst working on diff.

Could anyone suggest what I should check next. Thanks for your help.

Regards, Jim

SE5a rebuild/rolling restoration - no brakes today

Posted: Wed Apr 03, 2019 4:17 pm
by scimjim
Are you losing fluid? you might be pumping fluid into the servo or out of the rear slave cylinders - or the master could just be U/S and not pumping?

SE5a rebuild/rolling restoration - no brakes today

Posted: Wed Apr 03, 2019 4:29 pm
by philhoward
You can lose a lot out of a rear cylinder before it starts to become evident at the wheel..

SE5a rebuild/rolling restoration - no brakes today

Posted: Wed Apr 03, 2019 4:31 pm
by philhoward
Daft question - the clevis pin hasn't fallen out where the cylinder attaches to the pedal, has it? Normally if you lose one circuit of hydraulics, you still retain some braking from the unaffected circuit (although it might not feel like it).

SE5a rebuild/rolling restoration - no brakes today

Posted: Thu Apr 04, 2019 9:59 am
by Jpwill7675
Thanks Jim & Phil for the suggestions. The fluid level is still on max in the reservoir and the master cylinder is quite new. I will check the rear cylinders today and also the clevis pin. If its just the pin that will be a result ( & a bit alarming)

Cheers, Jim

SE5a rebuild/rolling restoration - no brakes today

Posted: Thu Apr 04, 2019 7:41 pm
by Roger Pennington
philhoward wrote:
Wed Apr 03, 2019 4:31 pm
Normally if you lose one circuit of hydraulics, you still retain some braking from the unaffected circuit (although it might not feel like it).
I didn't think the 5-series had dual circuit brakes?

SE5a rebuild/rolling restoration - no brakes today

Posted: Thu Apr 04, 2019 7:50 pm
by halfpenny
If the fluid remains on max, you don't have a leak. So either the master cylinder piston is not being pushed (pedal disconnected) or the piston seal is moving, but not sealing on the bore to allow pressure to be generated. Standard 5a is indeed single circuit.

SE5a rebuild/rolling restoration - no brakes today

Posted: Thu Apr 04, 2019 7:53 pm
by philhoward
Roger Pennington wrote:
Thu Apr 04, 2019 7:41 pm
philhoward wrote:
Wed Apr 03, 2019 4:31 pm
Normally if you lose one circuit of hydraulics, you still retain some braking from the unaffected circuit (although it might not feel like it).
I didn't think the 5-series had dual circuit brakes?
It doesn’t - I was having a blonde moment.. :oops:

SE5a rebuild/rolling restoration - no brakes today

Posted: Mon Apr 08, 2019 9:23 pm
by Jpwill7675
Managed to get at the rear cylinders today. The brake pads were pretty ropey and it looks like the wheel cylinder was the culprit.
IMG_4065.JPG
IMG_4065.JPG (321.52 KiB) Viewed 1009 times
I struggled to remove one of the solid brake pipes from the cylinder and will make up a new length from scratch. I am correct in thinking it should be 3/16 pipe into 3/8 UNF 24 male fitting?

Thanks in advance for your advice.

Regards, Jim

SE5a rebuild/rolling restoration - no brakes today

Posted: Tue Apr 09, 2019 6:04 am
by philhoward
The pipe is normal 3/16” - I think you’re right with the fitting too.