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jdamm

brake bleeding issue, brake pedal hits the floor

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Hi All,

so I'm at the last hurdle of the restoration before going for a "WOF"(warrant of fitness) New Zealand's version of a MOT, 

ive bleed the entire system 4 times now, in 2 different methods ( article from the faq and haynes manual),

i have a RHD 73' tii with a dual circuit system with 2 remote servos.

after the last round of bleeding, starting at the servos then rears then fronts, my brake pedal still hits the floor.

i have a completely refurbished system (new lines,hoses, re sleeved cylinders, servos and calipers),

Can anyone help either diagnose the fault in the system based on symptoms or give me a more specific RHD bleeding sequence to try?

thanks in advance!

 

EDIT; also just looked through the factory manual and notice i might have the front calipers upside down..... would this cause any issue with the upper, inner, outer sequence?

Edited by jdamm

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Calipers upside down means nipples at bottom? Then you won't get air out...that alone may make pedal go to floor... But it could also be that master isn't bled properly. Pressure bleeding helps, either with some hifangled equipment or by just using a large plastic syringe to blast fluid down the lines from the reservoir (nipples open)

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Definitely use a pressure bleeder for RHD brakes. Sounds like you are onto it though with the calipers being upside down. 

 If the system has been fully dry the the pressure bleeder ‘pushing from the top’ will help get the fluid through the master and onwards. 

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thanks dlacey & simeon for the replies,

ok so i have just finished flipping the calipers to opposite sides and re bled the system and pending a test drive it appears the problem is solved......

however based on your comments about pressure bleeding a RHD sys. i may have to look into that if the test drive isn't good, is there any mildy proper way to do so, say next step up from a syringe? or is it a workshop job?

 

thanks again

jules

 

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I bought an inexpensive tool, a vacuum tester / brake bleeding kit at a big box auto stores. You attach the device to each nipple with a tube, open the nipple and pull fluid through your brake lines, closing the nipple when you get fluid coming through without air bubbles. Just have to keep the reservoir topped up and the lid loose to compensate for the vacuum effect. Allows you to do a bleed without needing to get your wife to pump the brakes for you.

Sent from my STH100-1 using Tapatalk

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What I've resorted to before (but be warned, have rags ready, it makes a mess!) is to loosen the hard line fittings on the master cylinder and let a little fluid leak out of those joints, and then tighten them back down.  This is the most direct way to get most (though not all) of the air out of the MC itself.  Next, ignore the usual 'proper' order and bleed the cylinder closest to the MC (I assume in your case the RH front cylinder).  This lets you quickly push any remaining air out of the MC.  Finally, go back and bleed all 4 corners in the proper order to purge any air left in the lines and calipers.  If done with a good helper on the pedal and a close on on the reservoir to make sure you don't let it get low, this should do the trick without the need of a pressure bleeder.

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I made one of these and used it for years. I then got a cheap deal on the same thing but made by SP tools and never had to use it since. 

 

http://faculty.ccp.edu/faculty/dreed/Campingart/jettatech/bleeder/index.htm

 

I got mine for a lot cheaper than this but still, compare it with the one above. 

 

https://www.toolswarehouse.com.au/catalog/product/view/id/24745/?SID=ocfuq8knpj2bfht0cd40vvlni4&gclid=EAIaIQobChMI0o6vnqKm3QIVVT5gCh0_UgwPEAQYBCABEgIp7vD_BwE

 

 

 

 

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Another ‘low rent’ solution is to get a mountain bike tyre inner tube and cut the section out with the valve. Seal up one end with a knot (or similar) and the stretch the other end over the mouth of the brake reservoir and secure with a large hose clamp. A few pumps with a bicycle pump will pressurise (you only need about 10psi) and you should be good. Just watch the fluid level and make sure you don’t run it dry or you will be bleeding all over again. 

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I bought something like what Simeon is talking about.  Works absolutely great, even when bleeding a dry system. Around $50US.  I've tried the handheld vacuum suckers that you put on the nipple and have never had good luck- positive pressure seems to work much better for me.

 

Here it is on Amazon...  Do you guys get better shipping rates via Amazon?  But everybody sells them.

 

https://www.amazon.com/Motive-Products-European-Bleeder-Pressure/dp/B0002KM5L0

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On 9/6/2018 at 11:31 PM, Simeon said:

Another ‘low rent’ solution is to get a mountain bike tyre inner tube and cut the section out with the valve. Seal up one end with a knot (or similar) and the stretch the other end over the mouth of the brake reservoir and secure with a large hose clamp. A few pumps with a bicycle pump will pressurise (you only need about 10psi) and you should be good. Just watch the fluid level and make sure you don’t run it dry or you will be bleeding all over again. 

well being a avid mountain biker i liked the simpleness and backyard enginuity of this method so i gave it a crack, and it worked well!

I will eventually make up a pressure lid as i have a few spare reservoir lids and a valve spare but for now the bike tube is a "winner winner chicken dinner!"

 

and to the rest of you who commented, thank you for your advice, it's greatly appreciated! 

now all i have to sort is a stuck caliper as my bleeding prior to the pressure bleed obviously wasn't up to spec.

IMG_20180907_174554.jpg

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And just to be clear, that pump in the picture cost more than any bleeder kit we were talking about...  (Proper badass pump, tbh.)

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Hi Gruppe,

so i have hit more snags.....

front left caliper is stuck on, after reading other posts on this, i tried pumping pedal 10 times then starting car to see if pedal would drop like normal but it didn't move. aside from the caliper sticking and the pedal not dropping everything else seems fine and works.

so having a stuck caliper would give me that result right?

i haven't checked my boosters yet by removing line from manifold, should i try this?

my current thought is that in my rookie mechanic state i have got one of my new self made hard lines around the wrong way or maybe the feed to the left caliper wrong, has anyone got any pictures or diagrams of the correct RHD dual booster line layout so i can clarify?

my heads a bit of a mess TBH, after reading soo many posts that have individually specific symptoms, which my Tii has some of and none of ,aren't helping me narrow this down much.

oh and just for background info as stated on the 1st post above, all the brake parts are new or refurbished. ive pulled the pads out of the caliper in question then pumped the brakes to see if the pistons moved and they moved fine, however i didn't start the motor to see if they returned...

if you have any RHD specific guidance im all ears!

thanks in advance,

Jules

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Hey Jules,

What about your flexible pipes? Are they of unknown age?? They have a failure mode where they become one way valves...causing calipers to lock on.

 

RHD diagram I don't have, but in essence:

Two foot-pressure lines running from the master cylinder, one to each servo.

 

One servo has a 2 way fork output, these lines go to one set of pistons on the front calipers, one left wheel, one right wheel.

 

The other servo has a 3 way fork, two of the lines go to the other set of pistons on the front calipers, left/right. The other output has a 4cm long residual pressure valve and then the long hard line running to the back brakes. The RPV helps control brake pedal travel when rear shoes are worn/maladjusted by stopping them backing-off too far.

 

Normal faults of RHD brakes:

Flex hoses blockage

Front caliper piston seizure/corrosion

Servo inactive, servo leaking.

Edited by dlacey

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2 hours ago, dlacey said:

Hey Jules,

What about your flexible pipes? Are they of unknown age?? They have a failure mode where they become one way valves...causing calipers to lock on.

 

RHD diagram I don't have, but in essence:

Two foot-pressure lines running from the master cylinder, one to each servo.

 

One servo has a 2 way fork output, these lines go to one set of pistons on the front calipers, one left wheel, one right wheel.

 

The other servo has a 3 way fork, two of the lines go to the other set of pistons on the front calipers, left/right. The other output has a 4cm long residual pressure valve and then the long hard line running to the back brakes. The RPV helps control brake pedal travel when rear shoes are worn/maladjusted by stopping them backing-off too far.

 

Normal faults of RHD brakes:

Flex hoses blockage

Front caliper piston seizure/corrosion

Servo inactive, servo leaking.

 hey dlacey,

the flexi pipes are brand new, i forgot to mention that.

thank you for the break down of the circuit but could you possible be more specific about which line from where, for instance my thought process mentioned above makes me think i have a line from servo one to the caliper in the wrong feed hole into the caliper ( for example-  servo1 with 2 fork outlet to front right & left calipers top feed hole, servo2 with 3 fork outlet to front left and right calipers lower feed hole ).

i had the servo's rebuilt 2 years ago but re tested by the refurbisher 2 months ago to confirm they were still good (as the resto has taken WAY LONGER than expected), as they had warned me about the diaphragm perishing without use within 1 year of rebuilding.

as far as im aware my boosters work fine but im yet to test them by disconnecting manifold feed.

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