My stupid brakes grrrr

[HnM]

Ok, I have had these problems for a while now and prob mentioned em a million times.

I have a really soft pedal and can only lock the front brakes up(just)

rears are new wheel cylinders, pad etc and adjusted perfectly but no real input.

Master cylinder was replaced with a new unti to try and fix the problem but to now avail(but may have been dodgey?)

I bled the rears yesty so I know I have fluid reaching the rear and flowing etc

HLM is gunna lend me another master cylinder but sysdney is a long way to travel to pick it up and possibly drop it back if he can't wait till the stocko trip.

Any more ideas guys, I have done everything....

does yours have a proportioning valve? one that switches the brake bias to the rear when you have a big load in it? maybe thats rooted? sounds odd. i remember you telling me about it before.

[HnM]

I just finished putting an extension bracket on it to compensate for lift, just gotta go and put some paint on it. Still wouldn't explain the soft pedal though now would it...

[HnM]

There is also an audible "knock" in either the master cyl or the brake booster too.

If the brake booster was stuffed the brakes would be hard wouldn't they?? not soft??

Still points to this master or the prop valve I guess, just had a blat and no difference with the new bracket on the proportioning valve....

[HnM]

Just to ad more. I am about to swap master cylinders between my parents lux and mine and noticed that my "after-market" one has Aisin punched into it and is exactly the same as my parents except a coat of black paint and theres is silver???

I wonder if I got gipped eh, maybe they just painted mine then?

[malleetreker]

Possible Problems in relation to soft spongy pedal.

1) Air in brake lines. Bleed the brake system.
2) Deteriorated rubber brake hoses. Inspect all system hoses and lines, renew parts as necessary.
3) Master Cylinder mounting nuts loose. Inspect Master cylinder bolts (nuts) and tighten securely.
4) master Cylinder faulty.
5) Incorrect shoe or pad clearance.
6) Defective check valve, renew valve and bleed system.
7) Clogged Resevoir cap vent hole.
8) Deformed rubber brake lines.
9) Soft or swollen caliper seals.
10) Poor quality brake fluid. Bleed entire system and fill with new approved fluid.

Hope this might give a few areas to check

Regards
Mallee Treker.

[taziiy]

try backing the hand brake all the way off then adjust the rear brakes up once you have done that then adjust the handbrake back up ;)

[Ford Mav]

Make sure all ur brake lines are all solidly fixed at the point of change( where solid changes to flexible rubber hose) i know that it sounds a bit far fetched but this can cause the problem u r havin

Frank

[HnM]

thanks guys. I swapped master cylinders between the two lux's and found that I had good brakes compared to before. I'm not exactly happy with them but they should pass rego......

The knocking is still there though and is coming from the brake booster so that may need to be turfed later too.... Alot later.

[HellRazer]

Did you try bleeding the master cylinder???

[HnM]

yup, bled it this arvo aswell.

The master has improved it but I'm thinking there is more than one problem

[HellRazer]

Are all 4 of your pads wearing,ie are they all roughly the same thickness.sometimes the pistons can seize in the caliper and you may only have a couple of pads actually pushing on the disc.this wont cause the spongy pedal,you must still have air in there somewhere,but it will cause your brakes to be fairly ordinary.

sounds like a hose problem then...... i didn't think of it until malleetrekker mentioned it....... get somebody to push the brakes while you lay under the fourby and see if the brake lines swell at all.

[HnM]

Lines are fine, I replaced em about 18 months ago too. I wish everyone would get off the lines.

If its them I will eat my hat ;)

well if you have changed everything else........... you are fast running out of options mate........ short of buying a new fourby ;)

[nischev]

You mite find that the arm going from the booster to the brake peddle is adjustable (most jap ones are). Wind it out a bit if you are sure everything else is good and it will stop your peddle going as far. That is wat i have to do to mine as recommended by the brake speciallist.

[HnM]

booster and proportioning vales havent been done yet.

I just said that I have done the brake lines so I don't see how they become an option before the booster or prop valve now do they??

well we are a little touchy today aren't we ::)

[HnM]

You mite find that the arm going from the booster to the brake peddle is adjustable (most jap ones are). Wind it out a bit if you are sure everything else is good and it will stop your peddle going as far. That is wat i have to do to mine as recommended by the brake speciallist.


Thats the other thing I was thinking, we do it to forklifts all the time and if they're not long enough we cut a bolt down etc.

The one in mine has a small capped nut on the end so I may have to find a long nut that I can adjust

[nischev]

That would be on the m/cyl side the one u want to adjust is under the dash on the back of the booster ;)

[HnM]

I guess it def sounds like an option Stu, so this is prob the only place that could be causing the noise anyway.

Maybe take the booster off and check it all out then eh

[nischev]

The noise could be freeplay in that rod or the bushes on your brake peddle could be worn usually things like that are the simple ones that anoy you the most

[taziiy]

As long as it stops you when needede thats the main thing but i would definatly be looking at the booster now :o

[ferremit]

You should have pissed the rubber lines off and gone braided steel lines....fixed dads spongy brakes on his ducati....

i would be stripping your master cylinder down- my clutch cylinder went a few months ago, and just went really, really spongy- if they have just replaced the seals and not honed the cylinder, especially if there was any pitting in the bore, then your seals wont last long at all.... Pay the extra and get them stainless steel sleaved.

Other than that, suspect a trapped air bubble somewhere, or a leaking caliper pot seal....spongy pedals are resultant in the loss of pressure, either by air being compressed or leaking fluid.

[HnM]

Basically I feel a definate stop under the pedal when the noise is heard.
The bushes do squeak a touch but no noticable play in the pedal to touch if ya get my drift??
It's definately in the booster somewhere Im sure cause the sound comes from under the bonnet definately and it is the only moving part.
Sounds like the rod definately needs a tweak, I think in current form with a new/working s/h master it should pass rego but to get rid of this sound and possibly get some more brakes would be nice aswell.


I wonder if the noise is because the rod has wound itself back or forward?? Logic would say that it has de-adjusted??

[taziiy]

See what spares mark has available ???

[HnM]

Mark has a 2000 master and is gunna send a pic so I can see if its the same ;)

[taziiy]

what about the booster as well ???

[350rangie]

Early commodores cracked the firewall at the booster mounts. gave a s..t pedal and a noise. never seen it in a hilux but might be worth checking while youve got the booster off.

Mark has a 2000 master and is gunna send a pic so I can see if its the same ;)
ill send you the pic when i get home this arvo, i didnt get home to late last night

[2 BRUTAL]

spongy pedals with old rubber hoses can be caused by the hose actually expanding under pressure,

[HnM]

spongy pedals with old rubber hoses can be caused by the hose actually expanding under pressure,

duh

[roc70y]

TAKE THE ANTI SQUAL SHIMS OUT FROM THE FRONT CALIPERS AND TRY THAT!

[Thommo the Hut]

if you have put in new pads maybe they arn't bedded in,

i replaced my old commodore brake pads and had the spongy feel for a while untill the pads bedded in.

[HnM]

Okk, pads where replaced all round as said about 18 months ago but it hasn't been drivin a huge amount(apart from driving to Darwin like this :o)

I don't have the anti squel shims in there anyway.....

I tried Stu's idea with with rod on the booster. Slightly different set-up from the Nissan but done it all the same. Fire-wall side rod just takes slack outta the pedal (buger all there anyway) so I adjusted that, and the adjustment on the front definately is the one that free's slack between the booster and the master.

all adjusted and the knocking has improved to only a "bump" so I'm getting somewhere slowly. This master cylinder isn't as healthy as the one I swapped it with yesty but I might bleed it all up on the weekend and see if I can get an improvement with my cylinder and these changes....

craig heres the pics of the booster/master cylinder, this one came off a 2001 model, if its the same you are welcome to borrow it, and if it solves the problem ill sell it too you
http://www.4wdlinks.com.au/albums/hiluxmadness/alx.sized.jpg

http://www.4wdlinks.com.au/albums/hiluxmadness/aly.sized.jpg

[HnM]

thanks marko, is there four bolts holding the master to the booster or two?

looks like its a 2 bolt master from the pic

[taziiy]

Yeah looks like 2 too me too :o

should pick up those pegs mark...... and put that steel offcut away before somebody cuts themselves on it LOL

[HnM]

It does look like two to me unless that is the extra bracket that hold one of the valves.

The booster looks the same though..

I am checking another one out for cheap off a 97 model, if that doesn't work out Marko I should be able to get you to take a couple of measurements I'm sure, ;)

thanks marko, is there four bolts holding the master to the booster or two?
2 bolts hold the master to the booster