Deep brake pedal - sign of worn out break pads / - shoes?
Pajero I/O - 1999.
My brake pedal has become very deep, and I need to double push in order for the brakes to work properly.
Checked if there was air - there was not (as far as I could find on the two front calipers). At the rear wheels there are brake shoes.
However pads look worn on front left. Have not checked rear wheels.
Will the pedal get low if pads/shoes are worn, or are the brakes self-adjusting. I'm asking, because I may well shift pads and shoes myself, but if it is more reasonably another cause for the low pedal, I may need to put it in a garage.
Recommendations?
No - a "deep" pedal is not a sign of worn pads & shoes.
With all due respect, if you have to ask these questions, you lack the requisite experience to be doing a brake job on your own - either take it to a mechanic or get someone with experience to supervise you, the braking system of a motor vehicle is not an area to be learning on your own.
Most modern brake systems are self adjusting and the Pajero iO is no exception - a "deep" pedal would indicate that either there is a fluid leak somewhere - or - that the self adjusting mechanisms are not working, and are not compensating for the wear - with only 2~3 mm of friction material left, you are at a point where the pads & shoes need to be replaced as a matter of urgency and if you have to pump the pedal for the brakes to work, the entire system needs to be examined to determine why. A properly functioning system with worn pads & linings will stop the car without requiring the pedal to be pumped, so there IS another problem, which also needs urgent attention.
Finally - there are a number of differences between the different markets, so your iO may not be the same as mine - but, unless I'm mistaken, the rear drums can be removed without any special tools - there are two threaded holes on the drum that can be used to push the drum away from the flange, although you will probably need to unwind the adjusters before the drum can be removed - it is not unusual for there to be a "wear ridge" at the edge of the drum that may catch on the linings.
I will add a bit more....
Low brake pedal on my io come often with a useless hand brake, and adjusting the rear brake does fix it. Check here, Bob have a great advice to how removing the rear drum. http://pajerio.com/forum/rear-brake-adjustment.
A brake pedal that need pumping to be effective may have several problem, a faulty master cylinder, or air in the system or a few other...
Brake pads with uneven wear is another problem, probably from a caliper piston. The brake caliper piston have a square "o" ring, the square edge help the piston moving back after braking, this stop the brake pad to keep touching the disc after braking. If that square "o" ring doesn't do his job, the brake pad keep touching and wear faster.
3 mim left on the brake pads is not a urgent repair job, but still a good time to do the work. The pedal that need pumping .... I wouldn't drive like that. My advice is if you can, check and adjust the rear brake, bleed the 4 wheels.
Another thread with a few advices http://pajerio.com/forum/how-change-your-front-disc-brakes
The advice from Fordem is the best if you are not 110% sure of what you are doing. I hope that you can understand why:)
Happy io
rear drums
Finally - there are a number of differences between the different markets, so your iO may not be the same as mine - but, unless I'm mistaken, the rear drums can be removed without any special tools - there are two threaded holes on the drum that can be used to push the drum away from the flange, although you will probably need to unwind the adjusters before the drum can be removed - it is not unusual for there to be a "wear ridge" at the edge of the drum that may catch on the linings.
that is how i removed mine after i had to replace a wheel lug stud after i snapped one in half trying to take my wheel off.
in the end i bought a new lug stud and a new nut.
in regards to having the adjuster unwound, i just chocked the wheels and took the handbrake off. very simple... that allows the shoes to move inbound to the centre of the wheel and off the drum.
Thanks for the many good
Thanks for the many good advices.
I'm not stupid, and it must be possible to ask questions without being accused for being so....maybe it's because my mothertounge is not english?
I have previously rebuilt the whole break system on a Sunbeam Alpine, and I have several times back in time replaced brak shoes on VW Beetle. So - yes - I know the importance of well operating brakes on a vehicle ;-), however I have previously not dissicated a Pajero. And, btw right now I live in Maputo/Mozambique and I do not have all my tools and my garage with me, so I thought better off posting for some advice here on this forum.
I now understand that it could possibly be the adjuster mechanism in the rear wheels that need to be checked, as apparently these sometimes fails. When taking the rear wheel off, I expected a central wheel nut in order to unmount the brake drum, but there wasn't. Instead there was something that looked as it needed a special tool to be unscrewed, however I didn't look close enough or had not read any manual or googled any photos in advance, so I assumed it was so. However now I know better, and I will try over again. What size/threads are the bolts to be used for unmounting the drums? In this way I will be able to check more thoroughly the lining on the break shoes, and to bleed air from the rear part of the hydraulic break system. I'll probably need to get new breakshoes or to give them in for new lining, but it's hard to find both these services in my new city, which is not as organized as I'm used to. That's why I also posted for some advice on a thrustworthy supplier in S-A for shipment to Komatipoort, the boarder city.
all good
Sorry, I didn't mean to put your knowledge in doubt!! but this is a forum, and I don't know how good/bad! you are. Anyway, I don't know the size of these bolt but Bob wrote this:
To remove the drums you need two screws to press the drum off the axle, the bolts that hold the top radiator supports are perfect and you can take one from each side without effecting the radiator.
All the best with the repair....and let us know how you go....
Happy io.
Unfortunately, no positive
Unfortunately, no positive results.
Checked all 4 wheels, replaced front pads with new ones. Checked rear:OK (new ones only come with 4 mm lining - mine has 2-3 mm left).
Checked the auto adjusters, tightened some. Hand break became tighter.
Bled all 4 wheels for air (front calipers/rear pistons).
There is no external fluid leakeage or consumption - I hence asssume no leakage into brake booster.
Still got the low pedal.
The way the brakes work, it appears to me that one of the hydraulic circuits may be the problem. First push on the pedal goes very deep - almost to the bottom, and right front wheel appears maybe to not brake as well as the other wheels. When push-braking a couple of times, it evens out and all wheels brake well.
I assume it then must be air in the master brake cylinder? But this I have not bled before, and I'm not sure I would do that by myself.
Suggestions?
ABS?
Does the vehicle have ABS? Is the ABS light on? Have you had the ABS codes read?
Long pedal travel, which is how I interpret your description of "a deep pedal" is rarely a sign of trapped air - trapped air will give what is commonly described as "spongy" brakes, which would be more akin to a pedal with more "spring" than normal (imagine tying a dish washing sponge to the rubber pedal pad and then pressing it) than one with longer travel than normal.
Bleeding trapped air out of a conventional (ie non ABS) system follows the same basic principles wherever the air is trapped - so air in the master cylinder should not be considered as more of a challenge.
I'd like to ask why you have singled out the right front wheel as a possible "suspect", what symptoms have you seen?
Failed (or failing) brake symptoms can sometimes be misleading - a problem with the right front brake will actually result in the vehicle pulling to the left under heavy braking and vice versa - if you're certain the right front is the problem brake, you can try removing the caliper from the flex hose (or slacken the bleed nipple) and have someone step on the brake whilst you observe the way the fluid flows - it is possible for the flex hose to collapse internally and impede the flow of brake fluid - this by itself will not cause longer than usual pedal travel, but coupled with a binding caliper, loose wheel bearings or a warped rotor can produce a similar symptom.
Reply....
Does the vehicle have ABS?
Is the ABS light on?
NO Have you had the ABS codes read?
NO
ABS appears to work as it shall.
Long pedal travel, which is how I interpret your description of "a deep pedal" is rarely a sign of trapped air - trapped air will give what is commonly described as "spongy" brakes, which would be more akin to a pedal with more "spring" than normal (imagine tying a dish washing sponge to the rubber pedal pad and then pressing it) than one with longer travel than normal.
Long pedal travel is only on first push - then normalizes when pumped! Don't think I can call the pedal "spongy" or having more "spring" than normal after 2-3 "pumps".
Bleeding trapped air out of a conventional (ie non ABS) system follows the same basic principles wherever the air is trapped - so air in the master cylinder should not be considered as more of a challenge.
Well, there is no bleed nipple"
I'd like to ask why you have singled out the right front wheel as a possible "suspect", what symptoms have you seen?
Car pulls left on first push on pedel (long travel..)
Failed (or failing) brake symptoms can sometimes be misleading - a problem with the right front brake will actually result in the vehicle pulling to the left under heavy braking and vice versa - if you're certain the right front is the problem brake,
I'm not certain the front right is the cause of the problem, but I observe what I think is a less powerful breaking on this wheel BEFORE pumping the pedal. you can try removing the caliper from the flex hose (or slacken the bleed nipple) and have someone step on the brake whilst you observe the way the fluid flows - it is possible for the flex hose to collapse internally and impede the flow of brake fluid - this by itself will not cause longer than usual pedal travel, but coupled with a binding caliper, loose wheel bearings or a warped rotor can produce a similar symptom.
Yes, I understand this, however when bleeding air this on this wheel the flow was ok.
I agree with the right front diagnosis
The car pulling to the left on the first push is an indication of a problem with the right front brake, as would be the left front pads being more worn that the right (suggested rather than stated in your first post), because the left is doing more of the work.
The first place I would look is at the caliper slide pins, but since you've just changed the pads, you should have noticed if these were binding, and the second thing I would look at would be the flex hose - I note you mention the flow to that caliper being normal whilst you were bleeding, so, if it's not binding slide pins, I would have to guess the ABS may have an issue, but, this is just a guess.
Does the ABS light come on when you turn the key on before starting and then go back off?
With regard the master cylinder not having a bleed nipple - I've never seen one with a bleed nipple - you pump the fluid & the trapped air through to the calipers/wheel cylinders - the general rule is furthest to nearest - HOWEVER - some vehciles do NOT follow this rule, and some ABS systems require the use of the dealer electronic "tools" to bleed properly.
The non-ABS & early ABS equipped iOs require bleeding to be done in a modified sequence - for RHD, you start at the LR (furthest away from the master cylinder) followed by the RF, then the RR, and finally LF - this is typical of vehicles with what is known as "diagonal split" dual circuit brakes - there are two separate brake circuits so that a leak in one does not cause a total loss of braking.
If as your earlier post suggested you only bled the fronts, you might want to go back and do it all over again - air in one circuit can cause that circuit not to work whilst the other one still does.
Could you check one more thing for me please - follow the brake lines down the right frame rail to the rear axle - do they connect to a valve linked to the rear axle with a spring? Non ABS & early ABS systems have an LSPV (load sensing proportioning valve) later ABS systems do the proportioning using the ABS modulator.
.
The ABS on the io doesn't have his own fluid reservoir and I don't think that there is a special system/procedure to bleed it. Sometime it can be a bit hard to bleed the system properly. Start by the wheel the further away from the master cylinder. On some car you can get away by (with someone in the car) pedal up, open the bleeder while pedal is going down, close the bleeder when the pedal is down, let the pedal going up and start again. Another (better) way is to pump the brake pedal till it is hard (and a few more time), hold and push down, open the bleeder (slowly).....
By pumping the pedal till it does get hard, every time, does help to push the air to the end of the circuit. You may have to do that 5 to 10 time at each bleeder, make sure that the main reservoir is top up!. When you don't see air bubble in the hose (hose connected to the bleeder on one end then go in a glass, you must use this and not letting the fluid on the ground because you can see if there is air or not coming out) go to the next wheel. In some rare case it is a real pain to bleed the system, and even not possible to do it this way (there are other special equipment) but having the hose and the glass will show you that you have, or not, air in the system.
I am not putting your knowledge into question, you may have done this already, but if there is no air in the system and there is no leak, I don't think that a faulty internal hose or caliper would bring the pedal to the ground and you probably have other problem...master cylinder? or other...
I hope that you will get to the end of this...let us know
Happy io.
Strange...
Ok.. the slide pins on the front calipers are stuck - for sure. Checked this this mmorning. At same time bled that caliper again, my wife pushing the pedal. Could not see any air coming out, hhowever the bedal travel felt like getting ok! This was with engine off. I entered the car myself, tried the pedal, and it actually felt ok. Started the engine - still felt ok. I thought problem (with long travel) was solved. Assembled the wheel and did a small test drive. Same long travel again.... Strange.
Ok - I'll have to fix the stuck sliding pins on the caliper. Any how-to's on this? Or do I need a new caliper? Of course I can google, but would like your recommendations!
Thanks
caliper
I never done a caliper on this car, but this problem is probably the one making the front pads on the same side with uneven wear. I would try to get them to gently move with some WD40 or similar, once it start to move, pull apart, clean and grease with a suitable grease (rubber grease?) . Again, I never done one on this car, be careful that no seal get damaged. A google search is not going to hurt!!
Happy io...getting closer anyway.
How badly stuck are the caliper pins?
If they are just tight, you can probably free them by twisting back & forth with a pair of pliers - once you have them out, clean the cavity with a Q tip and alcohol, followed by a smear of rubber grease and reassembly - be very careful with WD40 and the like around braking systems, you don't want to get petroleum products on the seals. Also - there should be rubber boots where the slide pins enter the caliper, are those present & intact?
Maybe it's time to rebuild/replace the calipers.
Oh - for a how to - just google caliper rebuild - there are several excellent tutorials out there, not Pajero specific, but these are a very common style of single piston "floating" caliper, so instructions for a Honda or similar will be close enough.
PROBLEM SOLVED
I looked for a sliding pin replacement set in all the car-part shops I could find in Maputo, but everwhere they said that such things are not availaible and I would have to look for a second hand, complete caliper. This is Africa! So I looked for 'Used Cars Parts' shops, and was directed to probably the largest one in town....(you should have seen it - OMG!!) AND I managed to find one!! The left side one, however, the sliding parts are the same, so I was hopefully able to rebuild to get my right front caliper working.
Damn, the sliding pin (with the rubber return) was stuck! So, after 2 hours of struggle and methods not suitable to inform on this forum, we managed to get it loose. I took all the parts back home, and reassembled my original caliper, making sure it was sliding satisfactory. And, by luck, my toolbox had a tiny tube of brake caliper grease in it :-) - what a gift!
Anyway, after reassembly, putting on th ewheel and doing a test drive: The breakes are perfect! Better than ever, actually! So, the reason for the deep pedal travel was the stuck caliper. Can't really explain, but probably it was stuck in a quite offset position, and the piston needed a long travel in order to pinch/grab/fix to the disc. By making the sliding part work, the required travel/piston movement was dramaticallly reduced.
Cant explain it otherwise - any opinions?
Unfortunately the rubber cuff/sealing is broken, but this gives me time to get a proper one shipped from Norway - country of trolls.
That would be it
Binding slides will cause longer than normal travel - no two ways about it - and two hours to free a stuck slide, I have to admit, I have seen worse.
Several years back I did what would be called a "big brake" upgrade on a sport hatch - basically fitting larger disks and calipers to improve the braking ability - I went from the small OEM "solid" rotor to larger ventilated Brembo rotors (which I bought new) and used calipers which I completely rebuilt - one of the slide pins on the used caliper was that badly siezed in the caliper body that it took several days of soaking in penetrating oil, twisting back & forth with a pipe wrench and prying with the claw end of a carpenter's hammer with the caliper secured to a large plank of wood.
If I could have found another caliper in better condition I would have gone with that but my choices were limited - of course if you saw them now, you'd never know.
the why...
I looked for a sliding pin replacement set in all the car-part shops I could find in Maputo, but everwhere they said that such things are not availaible and I would have to look for a second hand, complete caliper. This is Africa! So I looked for 'Used Cars Parts' shops, and was directed to probably the largest one in town....(you should have seen it - OMG!!) AND I managed to find one!! The left side one, however, the sliding parts are the same, so I was hopefully able to rebuild to get my right front caliper working.
Damn, the sliding pin (with the rubber return) was stuck! So, after 2 hours of struggle and methods not suitable to inform on this forum, we managed to get it loose. I took all the parts back home, and reassembled my original caliper, making sure it was sliding satisfactory. And, by luck, my toolbox had a tiny tube of brake caliper grease in it :-) - what a gift!
Anyway, after reassembly, putting on th ewheel and doing a test drive: The breakes are perfect! Better than ever, actually! So, the reason for the deep pedal travel was the stuck caliper. Can't really explain, but probably it was stuck in a quite offset position, and the piston needed a long travel in order to pinch/grab/fix to the disc. By making the sliding part work, the required travel/piston movement was dramaticallly reduced.
Cant explain it otherwise - any opinions?
Unfortunately the rubber cuff/sealing is broken, but this gives me time to get a proper one shipped from Norway - country of trolls.
I just talk to a friend that used to do brake, and he confirm that a blocked caliper can make the pedal deep at the first pump then good...Yeah, I was wrong again... He said that the first pump will get the blocked side to flex (sometime it would even bend) giving the deep pedal, on the second pump the flex would be gone giving a good pedal....I have asked why it was good after the bleeding....because the pedal have been pump several time in a short period, the flex was gone...for a short while....
I am glad you got it fix...
Happy io
Syndicate
Checked the rear wheels
Checked the rear wheels through inspection holes: Like 3 mm left on each side. 2-3 mm on left front. 7 mm on right front.
Appears special tools are required to take the drum off.. damned!