Spongy Brakes after bleeding

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Spongy Brakes after bleeding

Postby Tuga2112 » Wed 11.07.2018, 09:35

Hello again.. more problems here before managing to get the car on the road for the "summer"

i rebuild both rear calipers.
left the system to dry out while rebuilding the calipers.
put them back in and bleed the whole system.
then bleed it again just to be sure theres no air.

took the car for a spin... and well.. it barely brakes at all when the foot is in the bottom... so i need help with what else can the problem be ?
i dont see any fluid leaking from the 2 pipes connecting to the master cilinder. so... help ?
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Re: Spongy Brakes after bleeding

Postby RonR » Wed 11.07.2018, 13:21

I had a similar experience when I rebuilt my rear calipers last year.

It seems that there are lots of places for air bubbles to hide in those calipers. I ended up undoing the bottom caliper bolts so they could be rotated to get the bleed nipple pointing straight up, then tapping the caliper with a rubber mallet while bleeding. If the system's been dry you might find the proportioning valves also need some persuasion to give up their air.
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Re: Spongy Brakes after bleeding

Postby Tuga2112 » Wed 11.07.2018, 14:55

RonR wrote: If the system's been dry you might find the proportioning valves also need some persuasion to give up their air.

do you mean to just bleed the rear and let a lot more fluid run through the lines ? or something different ?
i will unbolt the caliper and try to bleed with it tilted tonight.
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Re: Spongy Brakes after bleeding

Postby alan e » Wed 11.07.2018, 16:00

Buy a easybleed one man bleeding system it uses tyre pressure to push the brake fluid around the brake system, it makes it very easy when you are bleeding it on your own.
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Re: Spongy Brakes after bleeding

Postby RonR » Wed 11.07.2018, 18:24

Tuga2112 wrote:do you mean to just bleed the rear and let a lot more fluid run through the lines ? or something different ?
.


I meant to tap the proportioning valves with your rubber mallet while bleeding to dislodge any air in them.
Mine got better on the third full bleed, but I'd used well over a litre of brake fluid by the time I had a firm pedal.
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Re: Spongy Brakes after bleeding

Postby dapinky » Wed 11.07.2018, 19:29

I find that a metal spanner is more effective than a rubber mallet - it only needs a light tap (or series of taps) with a 19mm spanner as you bleed the system - just enough to agitate the air bubbles and free them.

Remember to tap the prop valves before the calipers though, otherwise any air freed from the valves may well then jam in the caliper.
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Re: Spongy Brakes after bleeding

Postby Tuga2112 » Wed 11.07.2018, 19:51

I have had another go at this. i forgot the tapping again. and im unsure where to tap now.
i did remove the bottom bolt and tilted the caliper as previously mentioned.
i also found one of the bleed nipples was letting fluid out through the threads while bleding. so assuming it was also letting air in. i took it out, and used PTF tape to improve the seal around the threads.

I did run/pump about half litre of fluid on each rear brake. halfway through one of the sides. i did find a decently sized volume of air.. and at the end there was no bubbles anywhere.
but when i took it for a test drive. as soon as the engine started. the pedal started to feel spongy again.

also i get this sound when pressing the pedal that seems like pumping air all the way down till the moment the pedal start to resist a bit and the brakes begin their minimal effect.

im wondering if i need to do something in specific to bleed the master cilinder ? (it was completely dryed out while i refurbished the brakes)
i get the feeling theres still air in the system, but its not in the lines themselfs. but in the pedal mechanism.

i also came across this

maybe for the 20 odd quid i should give that german ebay link a try ?
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Re: Spongy Brakes after bleeding

Postby HJ2 » Wed 11.07.2018, 21:02

As said: try using an easybleed or a proper brake bleeder.
In the end it will work!
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Re: Spongy Brakes after bleeding

Postby Tuga2112 » Wed 11.07.2018, 21:08

HJ2 wrote:As said: try using an easybleed or a proper brake bleeder.
In the end it will work!

I Have one of those tubes with a valve at the end. that you just put at the nipple and start pumping.

I can buy an easyBleed. or vaccum pump. those are within my budget. but i would need to know which of the 2 options is the most efficient?
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Re: Spongy Brakes after bleeding

Postby Fredjohn » Wed 11.07.2018, 22:11

Get an easibleed. Simple to use, controllable and one man operation.
And don't forget to tap the balancers to get the air out before doing same with the loosened calipers.
It is a long repetitive operation which requires patience followed by more patience and repetition.
Oh and as Geoff says, tighten the banjo properly, that's probably where air is getting in....
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Re: Spongy Brakes after bleeding

Postby Tuga2112 » Thu 12.07.2018, 08:02

Fredjohn wrote:as Geoff says, tighten the banjo properly, that's probably where air is getting in....

ive broken 2 banjo bolts already. im not sure how to tighten it properly anymore. i got new copper washers there and cant see any fluid leaking but still not sure how to be 100% certain theres no leak there.
1991 elan se
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Re: Spongy Brakes after bleeding

Postby Bern » Thu 12.07.2018, 10:53

Another recommendation for the easibleed - you can leave it going while you crawl around underneath tapping bits with your 19mm spanner (though maybe 20mm and 18mm will work as well? ;-) ).

I had an MG B that I couldn't bleed properly, I left it overnight with the brake pedal held down, and in the morning it was fine! Depending on where the air is, that might work!
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Re: Spongy Brakes after bleeding

Postby Tuga2112 » Thu 12.07.2018, 20:48

Bern wrote: I left it overnight with the brake pedal held down, and in the morning it was fine! Depending on where the air is, that might work!


has anyone tried this on the elan ?

i bought an e-z bleed and had another go today.
also tapped plenty all over the brake lines.
at the end i started the engine and pressed the brake (still on the air) a bunch of times. soon after starting the test i realised there must be a leak somewhere because the pedal travel before i found resistance was incresing over time.

i had a look around while my dad was pressing the pedal and on the first corner i noticed the bleed valve was leaking. so i used some TPF tape to improve the seal and put it back.

car down on the floor and took it up the street and down again.. the brakes dont feel perfect. but a lot better. and if there is a leak at the moment. it must be small, after about 2 minutes pumping there was no noticeable increase in the pedal's "free travel "

still. i need to figure out how to bleed this better because i still get something between 1/3 or 1/4 of the full pedal travel happens without any resistance.

on a somewat related topic. does anyone know the exact dimentions of the bleed nipples for both front and rear brakes ? the hex connections are starting to round a bit and i want to replace them before they become a problem.
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Re: Spongy Brakes after bleeding

Postby Giniw » Thu 12.07.2018, 21:53

If I remember correctly the bleed nipples are still available from sjsportscar (and probably deroure?). Or at least they were, not so long ago.
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Re: Spongy Brakes after bleeding

Postby Tuga2112 » Thu 12.07.2018, 22:38

Giniw wrote:If I remember correctly the bleed nipples are still available from sjsportscar (and probably deroure?). Or at least they were, not so long ago.

both SJ and rockauto have them.
im curious as of the exact dimentions as it turns out "non-branded" fittings like these are usually a lot cheaper. (for example. the SJ rear banjo bolts are 3.98 + postage + vat, while these are 3.79 delivered )

I found out the rear are deroure M10 30mm 1.5 pitch. which turns out to be rather dificult to find as most M10 nipples are all 1.0 pitch.
wasnt able to find specks on the fronts yet, but i will investigate further.
1991 elan se
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Re: Spongy Brakes after bleeding

Postby Giniw » Thu 12.07.2018, 23:45

I understand but to be honest I wouldn't risk a low quality bolt or bleed nipple for my brakes. The price percentage difference may be high but in the end the absolute price difference is very low, and as for the shipping costs I always have more to order than just a couple of bleed nipples so that doesn't really matter for me.
Last edited by Giniw on Wed 08.08.2018, 18:32, edited 1 time in total.
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Re: Spongy Brakes after bleeding

Postby Tuga2112 » Mon 16.07.2018, 14:48

took the car to work today as the brakes are as good as last time i bleed them (which is pretty much the same level of "goodness" as when i bought the car.

i still feel like theres plenty of room for improvement. but ideally i will be confirming that whenever i find a kind elan woner soul that will allow me to test drive their car. to compare the pedal feel.
1991 elan se
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Re: Spongy Brakes after bleeding

Postby Tuga2112 » Wed 08.08.2018, 18:30

continuining on the brakes saga.

the car needs MOT... me takes car for MOT... car fails MOT on 3 issues... cv joint boot with a cut... service brakes and parking brakes.

i was suspecting the parking brakes would fail, as my rear calipers seem to have a hard time to re-position themselfs to move the pads forward.
this is easily resolved by adjusting the cables (which in turn will make it unable to reset the position im sure)

refering the service brakes. the results were
"fronts are ok, just clean the rust of the discs and pads and will be fine"
"rear discs look good and the pads are fine. i think you need to clean the sliders"
it turns out this whole adventure started because i rebuilt the calipers all together.. so i know the sliders are in perfect working condition.
this leads me to the next suspect in the chain
proportioning valves. and how to rebuild them. or alternatively, upgrade them with competition grade stuff like a few other members have done before.

i feel inclined to upgrade with these as mentioned by Dave in the past for the folowing reasons.
seems to be less hassle to fit (remove old, put new in)
allows me to fine tune the rear brakes to distribute the braking power perfectly evenly, which to me sounds to be safer ?
im having some dificulty finding epdm o-rings with exactly 3.75 inside diameter (seems the common ID is 3.68) and the minimum purchase quantities are a bit high for someone not setting up a business of refurbishing prop valves

i would appreciate some help with either opinions or tips on how to find the correct o-rings
1991 elan se
1991 elan se project
91 MR2 Turbo (import) project
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94 4Runner
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Re: Spongy Brakes after bleeding

Postby Giniw » Wed 08.08.2018, 18:36

Have you had the opportunity to use the brakes after their refurbishment? Did you change the pads and rotors? (I suspect not as there is rust on them?)
As for the rear maybe you just swapped the pads from side to side and as a result they just need to bed in for a while?
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Re: Spongy Brakes after bleeding

Postby Tuga2112 » Wed 08.08.2018, 21:49

Giniw wrote:Have you had the opportunity to use the brakes after their refurbishment?

yes, 4 20mile trips mostly motorway. effectively commuted to work twice

Giniw wrote: Did you change the pads and rotors? (I suspect not as there is rust on them?)

no, although the car has got new ferrodo pads about 1 year ago and new front discs 2 years ago (done 4000 miles since 2016)
Giniw wrote:As for the rear maybe you just swapped the pads from side to side and as a result they just need to bed in for a while?

that sounds likely theres a 50/50 chanse of that.
i could swap them again in the rear for the sake of testing this out although that wouldnt increase the braking power, it would only re-balance the power distribution
1991 elan se
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