Imbalanced drum brake

[sharas]

Hi all,

My car is Roomster 1.2 and I'm very happy with it . Half year ago I changed front brake pads.

I failed National Car Test(NCT) twice due to rear drum brake imbalance:

1st time nearside brake was 2120kN Offside brake was 1330kN --imbalance 37%

parking brake nearside 2120kN and offside brake 0810kN --imbalance 62%

and nearside rear wheel was sticking.

So I cleaned the nearside back drum with WD-40 removed the dust and rust and the wheel span perfectly with no sticking.

So I thought I'll be fine

2nd time nearside brake was 1220kN and Offside brake was 2270kN --imbalance 46%

parking brake nearside 1220kN and offside 1810kN -- imbalance 33%

I think the problem was WD-40. The brake shoes are in good condition- very little worn.

So now I cleaned both rear drums with white spirit.

There is no garage to test brake imbalance and the next NCT is on Saturday.

Any thoughts or ideas will be appreciated.

[fabdavrav]

White spirit and WD-40!! NO.........NO.........NO........NO.....Use Brake cleaner, IPA (iso propal alcohol), or meths as these do not leave a film and evaporate off! Use this on the drums, discs, pads and shoes.......then carefully use a bit of 80grit sandpaper on the shoes and pads to rough them up abit afterwards!!!!

[Tech1e]

Are you adjusting them correctly?

[sharas]

Are you adjusting them correctly?

I wasn't adjusting at all. I don't know how to adjust- there is some pressure rode but I didn't touch anything.

After I applied WD-40 the imbalanced changed so I presume thats the case :S

I see that nearside brake and handbrake power(kN) is the same and offside is different so maybe it needs some adjustment.

But how to adjust correctly?

[Tech1e]

Please get someone competent to clean and adjust your rear brakes, spraying WD40 on them shows you know nothing about brakes so leave it to someone who does before you kill someone.

[bluecar1]

Please get someone competent to clean and adjust your rear brakes, spraying WD40 on them shows you know nothing about brakes so leave it to someone who does before you kill someone.

yep agree totally

WD40 is a lubricant, designed to reduce friction, think about it

YOU NEED FRICTION IN THE BRAKES TO STOP THE BLOODY CAR

if you do not understand the principle of how the parts work, do not touch them and get someone competent / qualified to do the work

technically depending on the amount of WD40 you contaminated the brake linings with you should replace them, i know i would

i classify brakes, steering and suspension as safety critical parts of a car, and if you do not understand them do not touch them, as put bluntly your life basically depends on them functioning correctly in normal and extreme conditions

[Salut]

Sharas, some years ago I had a similar problem with a Fiat I was running at the time. The problem was resolved by the having the whole brake system bled and the brake fluid renewed. My local and very competent garage confirmed that there was air in the system. The car was two years old at the time.

As an aside, Bluecar1, I have always understood that WD40 is a cleaner/releasing agent and absolutely not a lubricant.

[fabdavrav]

As an aside, Bluecar1, I have always understood that WD40 is a cleaner/releasing agent and absolutely not a lubricant.

Sorry to barge in.......WD-40 is a "thin film" lubricant as well......it also soaks into the pad material very well and this ruins the pads....it also leaves a thin oily film on the item that you have sprayed it onto...even if you wipe all the excess off! This is why IPA, meths or brake cleaner are better as they remove any oily films and then completely evaporate off leaving no residue!! And they do not permenatly soak into the pad material!!!

[KenONeill]

Big clue in the expansion of the name "WD-40" - Water Dispersant formulation number 40. Now do you know what it's made for?

It is not a thin film lubricant, but it does contain oil, hence the issues with reduced braking ability etc. It is also not a dismantling lubricant (although it sometimes works as one, but when you get something properly siezed then a real dismantling lubricant like PlusGas will prove almost instantly that WD-40 is not a dismantling lubricant).

{Meanwhile, back at the point}

I think you've got 2 issues now, one that the NCT showed up and one you've just caused.

The NCT has showed up that your rear brake linkage is out of adjustment, and possibly part-siezed. I can't comment further on this, because it needs physical access to and inspection of the car.

The one you've just caused is oil contamination of the rear brakes, so you now need a full set of new rear brake shoes, and the drums cleaning with a proper brake cleaner.

[bluecar1]

from wikipedia regarding wd40

WD-40's formula is a trade secret. The product is not patented to avoid completely disclosing its ingredients. WD-40's main ingredients, according to U.S. Material Safety Data Sheet information, are:

* 50%: Stoddard solvent (i.e., mineral spirits – primarily hexane, somewhat similar to kerosene)

* 25%: Liquefied petroleum gas (presumably as a propellant; carbon dioxide is now used instead to reduce WD-40's considerable flammability)

* 15+%: Mineral oil (light lubricating oil)

* 10-%: Inert ingredients

so it is going to leave an oily film and affect braking performance

[sharas]

Thanks everyone for time and effort especially to "fabdavrav" and "Salut". I cleaned rear drums and brake shoes with brake cleaner, sandpapered a bit brake shoes and bled the brake system.

My Roomster passed -- imbalance 6%, service brake effort 92%.

I know it wasn't wise to use WD-40

I had bad experience with garages before so it is not easy to find competent people to do the job.

Edited 12 June, 2011 by sharas

[fabdavrav]

Thanks everyone for time and effort especially to "fabdavrav" and "Salut". I cleaned rear drums and brake shoes with brake cleaner, sandpapered a bit brake shoes and bled the brake system.

My Roomster passed -- imbalance 6%, service brake effort 92%.

I know it wasn't wise to use WD-40

I had bad experience with garages before so it is not easy to find competent people to do the job.

Glad it worked out all OK!!! Thats what we are here for!!!

Garages....hhhmmmmmmm.......I know what you mean......I taught myself because of same reason!!!

Haynes don't do a manual for the Roomster....but as the front of the car is a Fabia....maybe get the Haynes book for the Fabia MKI (Fabia MKII is based on MKI and Haynes only do Fabia MKI)....this book should point you in the right direction until a proper manual is made!!!????

Edited 13 June, 2011 by fabdavrav

[bluecar1]

sharas,

sorry for jumpimg so hard, but what you did was dangerous

anyway glad you got it all sorted

if you ever have a similar type issue, feel free to post and ask a question before you get the WD40 out next time