Technical Brakes Imbalanced Across Rear Axle (MOT Major Defect)

[DTanner]

I took my 2009 Fiat Panda Dynamic Eco 1.2L Petrol, with 145k miles on the clock, for its annual MOT and had a single fail:
“Brakes imbalanced across an axle Rear (Axle 2) [1.2.1 (b)(i)]“

Talking to the tester there is a 40% imbalance and the reduced braking is on the rear passenger side. The imbalance was evident in both foot brake and handbrake testing. I had a look for some guides and found this, which looks useful – I will try and follow this:

I will check both sides at the rear, just to have a good comparison as well. These are the steps I am expecting to make:

• Raise the rear of the car
• Remove both wheels and drums
• Check under/around boots of wheel brake cylinder for leaking
• Carefully push back piston on each side of cylinder to show it moves freely
• Inspect brake assembly for issues
• Check bleed nipple and brake pipe for leaking/issues
• If all else looks fine I will bleed the brakes for signs of air

Hopefully I will find something I can work with (I will provide an updated after my initial inspection). I actually have a spare set of shoes, brake fluid and a pressure bleeder (that connects to the reservoir for bleeding).

Any advice? Anything else I should look out for or things to be careful with?

 

[Greasytrucker]

I’d have thought if it was a leaking cylinder the backplate would be wet and the tester would have spotted this. More likely to be something seized or an adjustment issue

 

[DTanner]

Ok, I had an inspection and think the wheel cylinder is leaking fluid, causing my issue. The cylinder on the other side also does not look great but not as bad (some leaking in the rubber boot - but no big issues outside it). I will try and post some pictures.

My plan is to fully strip down, clean the area and replace with a new cylinder and shoes on both sides. As I am replacing the shoes on both sides I may as well replace the cylinders on both sides (give one is leaking badly and the other is leaking a bit).

My plan (after removing wheel and drums):
1) Tighten brake fluid reservoir
2) Remove the dust cover and wheel bearing to provide access
3) Remove the shoe assembly
4) Loosen the two screws holding the wheel cylinder. May require loosening the back plate (that the parts mount on) for access
5) Pop the wheel cylinder out of the back plate (so it hangs on its pipe)
6) Throw a wrench/spanner on the union fitting between the brake pipe and the wheel cylinder and screw the wheel cylinder off (by turning the cylinder)
Then refit new components like this in reverse. I need to check shoe adjustment but it seems ok. My biggest worry is damaging the brake pipe.

Some questions:
Is it advisable to remove the wheel bearing for access and later put it back on? I understood that this is not advisable but not sure if it matters if it is returned to the same wheel. Should I regrease it as I put it back on - any recommended grease?
Do I need a pipe wrench or just a standard spanner to remove the union fitting between the wheel cylinder and brake pipe (the pipes are in good condition) - if so what size?
Any other advice?

 

[Pugglt Auld Jock]

Ok, I had an inspection and think the wheel cylinder is leaking fluid, causing my issue. The cylinder on the other side also does not look great but not as bad (some leaking in the rubber boot - but no big issues outside it). I will try and post some pictures.

My plan is to fully strip down, clean the area and replace with a new cylinder and shoes on both sides. As I am replacing the shoes on both sides I may as well replace the cylinders on both sides (give one is leaking badly and the other is leaking a bit).

My plan (after removing wheel and drums):
1) Tighten brake fluid reservoir
2) Remove the dust cover and wheel bearing to provide access
3) Remove the shoe assembly
4) Loosen the two screws holding the wheel cylinder. May require loosening the back plate (that the parts mount on) for access
5) Pop the wheel cylinder out of the back plate (so it hangs on its pipe)
6) Throw a wrench/spanner on the union fitting between the brake pipe and the wheel cylinder and screw the wheel cylinder off (by turning the cylinder)
Then refit new components like this in reverse. I need to check shoe adjustment but it seems ok. My biggest worry is damaging the brake pipe.

Some questions:
Is it advisable to remove the wheel bearing for access and later put it back on? I understood that this is not advisable but not sure if it matters if it is returned to the same wheel. Should I regrease it as I put it back on - any recommended grease?
Do I need a pipe wrench or just a standard spanner to remove the union fitting between the wheel cylinder and brake pipe (the pipes are in good condition) - if so what size?
Any other advice?

We have a 2010 Panda Panda Dynamic Eco (1.2) we call "Becky" and I do take the complete hub off when removing the shoes. It just gives so much better access. I've done it on others too and had no problems - they seem to pull off easily without leaving the inner bearing on the axle. You're supposed to use a new locking nut when refitting but I've always just reused the old one and never had a problem - it's done up pretty damn tight! Two of the cylinder retaining bolts are difficult to get at, but not impossible. The manual tells you to undo the backplate screws but mine were so rusted they'd have snapped or rounded - they're Allen screws - so I just struggled on. Managed one but couldn't get the other so I got Kenny, at our local wee FIAT indy to do it for me. Self adjusters need a good freeing off. Get a "proper" single hex split ring spanner for the tube nuts. On ours it was 11mm for the male and 13mm for the female tube nuts.

Greasing bearings? Have a look at them. Over stuffing with grease is as bad as having too little because it will stop the balls/rollers from rotating properly and may cause grease to leak out onto your new brake linings! If they look like they could do with some I will give them a wee lick of HMP wheel bearing grease - probably a lithium based product but NEVER molly in a rolling contact bearing as it's too "slippery" and will make the balls/rollers "skid" against the races. I've had the inner race and balls fall out on a couple but they went back together quite easily with minimum force and were fine after.

I presume you are "tightening" the reservoir top to form a vacuum so stopping fluid transfer when the pipes are undone? I do this by putting a clean crisp packet paper under the lid and then screwing it back on. Crisp packet material doesn't seem to dissolve in brake fluid like a plastic bag will. Some designs of reservoir prevent this so another way is to depress the brake pedal and block it down. This stops fluid transferring from the reservoir into the master cylinder bore. I'm not so keen on fully depressing brake pedals though as it forces the seals into a part of the cylinder which is not used in normal driving and I worry about possible damage to the seals especially if it's an old cylinder. Pinching off flex hoses is a last resort for me as I worry about damaging the hose reinforcement.

I'm lucky in that I have pipe flaring tools, so if I have trouble with a pipe union, I just cut the pipe at the union and make a new pipe up. Have to admit, making new pipes is something I find great fun!

Have a good look at the flexi hoses. If they've never been changed, at this age, they'd be the better of being renewed.

Also, what sort of condition are the drums in? Becky's are pretty rough and I really should have renewed them.

 

[koalar]

Lots of possibilities

Friction material delaminated
Friction material wor to the rivets
Adjuster seized
Adjusted ratchet worn smooth
Bimetallic strip fall off
Broken or damaged spring
Contaminated pads,with or without
Seized wheel cylinder
Spring fallen off or damaged

Normally is a question of gathering as much evidence first

Then visually inspect

Of course you can just whip the wheel and drums of, there's a good 80% chance it weeping and obvious

I'd lift a wheel and apply turn the wheel and see what ratchet it starts to grip, and then how hard it grips

If one side starts way before the other it's probably a mechanical or seized type problem

If one side just applying more force it's likely to be a friction material error


If it's a seized piston you can tap.it back and forth to free it up and it will pass an MOT, take the pressure of on the retest, will need changing though as they will start weeping within a year, but you can do this at your leisure


Some easy test here https://www.fiatforum.com/threads/koalar-random-thoughts.503176/post-4704415

It for the later euro 5 brakes but the principles are the same

 

[koalar]

Some questions:
Is it advisable to remove the wheel bearing for access and later put it back on? I understood that this is not advisable but not sure if it matters if it is returned to the same wheel. Should I regrease it as I put it back on - any recommended grease?

Much easier to remove the hub, can be done both eays

Do I need a pipe wrench or just a standard spanner to remove the union fitting between the wheel cylinder and brake pipe (the pipes are in good condition) - if so what size?
Any other advice?

Yes

They are thicker with a cut out to go over the pipe

Get a 10mm one end and 11mm the other

It will do almost everything you will come across on a fiat, plenty of people haven headed this warning and twisted the pipe off, more costly and time consuming

Needs to fit well, so worth spending on a quality part

I have several

The laser banded one fits the nicest

Just hold the nut still and twist the cylinder off, otherwise you risk damaging the pipe

 

[koalar]

A decent 6mm hex socket will make undoing the back plate and access the wheel cylinder bolts much easier

 

[koalar]

Ok, I had an inspection and think the wheel cylinder is leaking fluid, causing my issue

A 40% imbalance caused by a weeping wheel cylinder should be fairly obvious,

 

[Pugglt Auld Jock]

Much easier to remove the hub, can be done both eays

Yes

They are thicker with a cut out to go over the pipe

Get a 10mm one end and 11mm the other

It will do almost everything you will come across on a fiat, plenty of people haven headed this warning and twisted the pipe off, more costly and time consuming

Needs to fit well, so worth spending on a quality part

I have several

The laser banded one fits the nicest

Just hold the nut still and twist the cylinder off, otherwise you risk damaging the pipe

The best split ring brake union spanners I have are branded "Williams Superslim" They are very robust, feel so nice in your hand and fit the nuts exactly. Seldom will they round a nut off. Unfortunately I don't have a full set though, having bought then singly as needed. Some are also now pretty much defunct - like the one for getting at the front drum adjuster on the old minis which "hid" behind the steering arm and the square one which fitted most other manual adjusters on the old cars. I also have one which is for imperial size tube nuts, haven't used that in years. A few years ago I saw a set of Clarke branded ones on special offer and it had all the sizes I was missing, they were very shiny too! They perform very acceptably but are not a patch on the Williams.

Thanks for mentioning freeing the cylinder from the backplate and then holding the nut whilst twisting the cylinder off the nut. This is a very useful technique which less experienced folk don't think of and often saves making up pipes. Sometimes though, as I'm sure you'll have found, if the nut is hopelessly seized to the pipe it might need to be twisted to an unacceptable degree to tighten it which then means you're making a new pipe anyway. Well worth trying though.

 

[ZaphodB]

they were very shiny too!

Always a bonus when buying

 

[Pugglt Auld Jock]

Always a bonus when buying

Oh yes, I'm easily subverted by "shiny". "Nice 'n shiny" is one of Rainman Ray's frequently used descriptors. I like his you tube posts.

Edit. Unfortunately, over the years, I've found that "very polished and shiny" when it comes to hand tools, quite often equates to "poor quality and brittle" You have to be careful. However there is now a lot of "higher mid range" brands which are pretty good. Certainly good enough for serious hobby use. I have some branded Bergen - I've got a very robust set of deep impact sockets of theirs which have taken some serious abuse on my big air gun. I also have some Neilsen and one US Pro branded and a few others. I also have a set of American Gear Wrench go through sockets which are generally pretty good for what I want them for, the ratchets are robust but the sockets seem a little soft compared to my old British tools - Britool, King Dick and others - bought many years ago. I don't know if later offerings are now better, but over the years I've found budget tools branded "India" tend to be brittle and break at quite low stress levels so I avoid them - anyone bought such stuff recently?

 

[jackwhoo]

Not too shiny or they attract the sticky fingered or a "friend" borrows for a few days which = about a year and either never comes back or "friend " finds it in their garden remembers it's yours, returns it a rusty mess but expects much gratitude for returning tool

 

[ZaphodB]

That reminds me of my brother in law who lent my step father something (a chain saw I think) ...

Didn't really notice it gone until he needed it, my step father offered to loan it to him
Til my brother in law piped up "wait a minute"

 

[jackwhoo]

For op
If at 16 years 145000 miles and rear brakes never overhauled.
May I suggest the full pre-assembled shoes, springs, adjuster kits.
Also available with slave cylinders
Drums too if original drums

 

[DTanner]

OK, here are some images of the situation. I provide these for: 1) the bad side as tested in the MOT and 2) the opposite side for comparison.

1) THE BAD SIDE:
Images from the side that the MOT tester deemed bad. Not as bad as I expected but evidence of leaking cylinder - most notably it looks a bit damp (with leaking brake oil).

Liquid emerged from under the wheel cylinder boot:

The brake pipe looks troublesome...

THE GOOD SIDE:
Looks similar to the bad side, but most notably it looks like dry dust from the brakes. Generally cleaner and not as much crud clumping and sticking. Liquid ran from under the wheel cylinder boot when I lifted it (on the good side too).

The brake pipe looks problematic on the good side too...

 

[jackwhoo]

Both cylinders are shot and need replacing .
Shoes both sides because one side contaminated
Plenty of penetrating oil on brake pipe nuts.
I've seen a lot worse that ended up being ok to undo.
When tightening pipe nut it only needs to be "nipped" up you can always tighten slightly more if needed. You can't un-crush the pipe flare if over tightened.

 

[Pugglt Auld Jock]

Not too shiny or they attract the sticky fingered or a "friend" borrows for a few days which = about a year and either never comes back or "friend " finds it in their garden remembers it's yours, returns it a rusty mess but expects much gratitude for returning tool

When I left Firestone Racing and went into the workshop I bought a pretty comprehensive set of everyday tools to complement the random tool kit I'd built up over the years. I had one of the better kits in the shop and other workers would, from time to time, ask to borrow stuff. Mostly it got returned but sometimes not and sometimes they'd break it and buy an inferior one as replacement - if at all. Being new in the workshop I didn't like to refuse folk or get too demanding when someone didn't return a tool. There was an older guy in the shop who kind of took me under his wing and one morning, when I unlocked my top box and lifted the lid, I found a big sticker stuck to the inside, plain for all to see, "Please don't ask to borrow tools, as a refusal often offends" It stopped people asking to borrow but, to this day, I've no idea how he got it stuck inside the locked box without me knowing.

Since then I've generally refused to lend tools or gardening equipment. Very occasionally though I will make an exception - probably less times than I have fingers on both hands - and the last time it was my expensive ctek battery charger, which I lent overnight to a friend to charge his wife's seldom used Kia. He returned it next day with much thanks and I put it back in it's box on the shelf. Many months later I went to put it on one of my workshop batteries for a maintenance charge and it wouldn't charge - lights went on but it wouldn't initiate a charge. Damn I thought, that battery (which is pretty old having been taken from my boy's Punto years ago when we fitted a new one) is now goosed. So I then put it on my other, much bigger, workshop battery which I mainly use for jump starting, and it was the same story. Lights came on but no charge started. Could it possibly be both these elderly batteries have packed in at the same time? Decided to try it on Becky's quite new and "known to be good" battery - same result. This time I monitored the output with my multimeter and confirmed - no output. I've since bought a new Ring smart charger - about half the price of the Ctek - which is charging all these batteries just fine. Trouble is I can't really prove he broke it and anyway, it's been months now since he returned it. I've decided to just "suck it up" and keep reminding myself DON'T LEND TOOLS TO ANYONE!

 

[koalar]

The good news

The dust cap 2 is present, they are very handy to place on the pipe when you undo it to stop it dribbling on your drive

Because theres no room to get a ring spanner on it, red line to the right


And the condition of bolt 1 I would not even try an open ended spanner on it and loosen the back plate first

 

[Pugglt Auld Jock]

Both cylinders are shot and need replacing .
Shoes both sides because one side contaminated
Plenty of penetrating oil on brake pipe nuts.
I've seen a lot worse that ended up being ok to undo.
When tightening pipe nut it only needs to be "nipped" up you can always tighten slightly more if needed. You can't un-crush the pipe flare if over tightened.

The first picture shows a badly leaking cylinder and contaminated shoes, complete rebuild required. The brake pipe looks a bit "flaky" so I'd be doing a pipe too. That's easy for me to say though because I have a roll of kunifer, tube nuts and a flaring tool.

On the other side although the shoes are not yet contaminated you can see the start of a leak past the rubber dust boot so it needs done too and as the shoes will be new on the other side you should fit new ones here too - they come in axle sets anyway. The pipe on the "good" side looks much better and with some releasing oil - like Plus Gas, PB Blaster or similar. WD40 whilst a very useful fluid is not as good specifically as a releasing agent - and maybe some heat from the likes of a plumbers torch or similar, I think you'll find it'll undo without too much drama - but you'll only know when you try. Clean out the drums well with spray brake cleaner or you'll just end up contaminating the new linings on the "bad" side.

First thing to do is to slacken off the handbrake cables as far as they will go. then, when the cylinders, shoes, adjusters etc are all reinstalled manually "trip" the self adjusters up until the linings are lightly rubbing on the drums - If you don't fit new drums, file or grind off any wear ridge on the outer diameter of the old drums before refitting the drums for adjustment - Then take up some of the slack on the handbrake cables, doesn't need to be anything precise at this stage, and. with the drums on, yank the handbrake up and down vigorously a number of times to settle the shoes against the drums. You may then find you can take the self adjusters up another "click" or two. Only then should you finally adjust the handbrake until it lust starts to move the lever arm on the shoe away from it's resting position. It is correctly adjusted when it just pulls the lever away from it's stop. The number of clicks on the handbrake is almost irrelevant - as long as it adequately applies the brake of course. Don't over tighten the handbrake to get just two or three clicks as we all did with the older cars. If you over tighten the hand brake cables the self adjusters can't return far enough to "grab" the next tooth on the self adjuster and will fail to function, then you'll end up with a long pedal travel as the shoes wear.

 

[koalar]

Here's how I deal with the corroded brake pipes

Always worth testing first it might not be as bad or as tight as it looks

Koalar random thoughts | FIAT Panda (Mk3)

Clutch, gearbox problem You can see the pessure plate here And from further back The inside is normally covered in oil if the input seal/bearing has gone

www.fiatforum.com

I haven't damaged one in the last 20 years, but it does take experience to know how much pressure and heat to apply, something it takes several attempts, I sure I messed up my fair share when I started out

If it requires heat it will need coating in grease afterwards as the plastic coating gets burnt off, a good thing as the union has more room to spin freely