Method for bleeding full system

[alan.gilbert_6384]

Hi all, hope you're all well and enjoying the lovely 21 degrees here in England ;).

Brake system bleeding (single line, Spitfire 1500).  So after a full rubber replacement of the entire braking system (after find a leaky master cylinder with very suspicious degraded seals in it), I thought I would research how to bleed the system.  The standard appears (from WSM) to be thus, 1st the wheel calliper furthest away from the master cylinder, so in our case with RHD cars its the FNS.  Then the next front calliper.  Then on to the rear, starting with the furthest away.  The Haynes has no sequence, but I always thought it should be rear furthest away first then working back towards the master cylinder ???

But here's the thing, I cannot find anything in the WSM which says LHD cars are different, which they should be according to the instructions it should be the FOS that's furthest away from the master cinder on LHD.  Both LHD and RHD cars have the same pipe runs from the T piece which is located in the same place on both drives of cars ie by the FNS calliper.

Has anybody got any help advise ??

 

NOTE; Also the fluid had been replaced by the PO some time ago to DOT5, which I like as its more stable, but having found the seals in the master cinder turn to goo literally, I decided to follow some advise on this forum and replace all the rubber bits .  When I did the front callipers I could see remnants of the old fluid trapped in the callipers when I serviced them.  some to think about when going from older stuff to DOT5.

[GrahamB]

I had read that disc brakes should be bled before starting on drum brakes.  But which is the caliper furthest from the master cylinder?  The n/s wheel is furthest from the master cylinder but because of the brake pipe routing, at least on the Spitfire 1500, the o/s front caliper has the longest pipe run.  I have tried bleeding the o/s front first and also the n/s front first.  It did not appear to make any difference so the exact order does not appear to be critical.  After recently changing just the master cylinder, I bled the n/s front caliper first thinking that any air bubbles reaching the four way connector would rise up the vertical pipe run to this brake first.  It appeared to work as bleeding the other three brakes made little difference to the feel of the brake pedal.

[dougbgt6]

Yeh, furthest away on an RHD is driver's side rear closest is passenger side front. Never heard of bleeding the discs first, can't think why you would need to? Not sure about LHD, however my observation is doing the furthest away first gives the least fluid loss,  nothing more. But keep it in a jam jar for a couple of days and the bubbles subside, good as new.  So, just go for it!

Doug

 

[Anglefire]

I've always bleed farthest from the master cylinder first - which would be NSR, OSR, NSF and OSF - rear is probably less important on a single circuit. 

I use another person on the brake and get them to press the peddle strongly and quickly a couple of time, then not so quickly, but smoothly as I then lock off the nipple. Repeat for all other and repeat until a firm peddle is achieved and no more air comes out. On brand new brakes I have found they they can be a little spongy even when fully bleed because the rubber tends to pull the pads away from the disks until they have settled down.  

[Pete Lewis]

the problem with which way to bleed is a bit like marking the rear spring "front"   when some one asks there is a response often based on nothing of importance

but there 's the answer to the question ...the idea to do calipers first is only they have more capacity and hold more air 

then do the rears so all the remaining air gets a squirt to the remaining smaller capacity rears 

it the real world  it matters very little how you do this  more how you pump the pedal where the catch jar is and whether you nip the nipple at the end of a down stroke 

so start where ever you feel happy with   , with decent M cyl operation   a long bleed tube to hold the catch jar higher than the wheels  a quick down stroke 

nip nipple   slower return  open nipple quick down   will work well where ever you start from   as doug say  just go for it  ignore the myths 

if you want to save a pair of hands  block the bleed tube end  and slit 20mm witha stanley blade in the tube sidewall and you have a ready made valve 

Pete

[johny]

Think youre right Pete but its funny how the workshop manual is quite specific even giving separate instructions for left and right hand drive:

[68vitesse]

Air can be drawn down the threads of the bleed nipple if it is not tightened between pedal strokes.

Regards

Paul 

[Pete Lewis]

there'sno fun in following the rules   most rues need to be .....broken  Ha 

on the prod line we had evacuate and fill   , but needs seals that take 0 vac    , this was held to check no leaks and then whoosh in goes the fluid ...no air  at all 

no bleeding and no recycled fluid to store as was the old pressure fed afair which had pressured input and a vac at the nipple 

instructions are there to aid information   so yes they are instructions  someone has to write it to satisfy the inquiring mind , doesnt mean its completely right 

but it does give you the clues to success  ,  Ive written a good few manuals in my days 

test yourselves write how to crack an egg    ...everyone does it differently    the result is the same 

Pete

 

 

[dougbgt6]

35 minutes ago, Pete Lewis said:

test yourselves write how to crack an egg 

My granny used to make Easter ornaments out of egg shells.  She'd stick a pin in either end of the egg puncturing the yolk sack, then blow the contents our into to a cup. All that remained was the empty egg which was then boiled wrapped in onions skins to colour it. This used to be a popular thing to do, didn't waste the egg, provided a free decoration and resulted in  the term "Don't teach you granny how to suck eggs!" Or blow, in my gran's case.

Doug

[Peter Truman]

3 hours ago, Pete Lewis said:

there'sno fun in following the rules   most rues need to be .....broken  Ha 

Pete

 

 

Drift! I remember having to go and see the head of one of Melbournes premier private schools at age 15, as i frequently was prone to do, where he dressed my mate and me down starting with "I know rules were meant to be broken, but not with the BLo*dY frequency that you break them!!" 

[alan.gilbert_6384]

5 hours ago, dougbgt6 said:

My granny used to make Easter ornaments out of egg shells.  She'd stick a pin in either end of the egg puncturing the yolk sack, then blow the contents our into to a cup. All that remained was the empty egg which was then boiled wrapped in onions skins to colour it. This used to be a popular thing to do, didn't waste the egg, provided a free decoration and resulted in  the term "Don't teach you granny how to suck eggs!" Or blow, in my gran's case.

Doug

Your Grandad was a very lucky man 🤣

[Stratton Jimmer]

Pete's advice about having the bleed jar higher than the slave cylinder is golden. Since using his technique I have had no problems whatsoever with brake bleeding. The order I have used is OSR, NSR, OSF, NSF.

[PeteH]

I`ve recently had very good results with a vaccuum Bleed kit. 3 (or4?) full fluid replacements so far and nice hard pedals first time. Easy "one man" (other gender available) operation too.

Pete

[Mjit]

On 16/12/2022 at 20:39, Anglefire said:

I've always bleed farthest from the master cylinder first - which would be NSR, OSR, NSF and OSF - rear is probably less important on a single circuit.

I often see this written and while I agree with "farthest from the M/C first" part disagree with the order.  Yes, the NSR is farthest from the M/C 'as the crow flies' but it's the OSR that's farthest for the fluid to go, the pipeline going (on both Spitfire and 2000 saloons at least) OS bulkhead->NS 4-way distribution block->pipe down NS->NS 3-way distribution block->OSR wheel.  Then it's the OSR, then it's actually the OSF 9pipe from NS 4-way block to OSF is longer than the one to NSF) and finally NSF.

[Pete Lewis]

you see as everyone does it differently it doesnt matter a hoot    just bleed the thing and have a nice day

Pete

[johny]

Definitely dont put your leaf spring in the wrong way round though😂

[Pete Lewis]

H A hAAAAAGH  

happy what nots !!

Pete

[Unkel Kunkel]

A long, long time ago.. there were some wonderful things called “ABV”s  - automatic bleed valves.They were fitted in place of the standard bleed valves.

Changing fluid, or bleeding the brakes was so quick and simple.

It just meant undoing all  the ABVs   half a turn or so then it only needed one person  pumping the pedal a few times.

The main thing was being watchful of the m/c reservoir level.

Short piece of tubing and jar to each ABV avoided mess,  but wasn’t required for the bleeding process itself.