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Brake disc ok?

Posted: Fri Dec 11, 2009 5:21 pm
by brorabongo
Is this disc ok?

Image

I never noticed a notch on the other disc which was fitted first. The new discs have stopped the steering wheel wobbling when braking though.....thank goodness.

Re: Brake disc ok?

Posted: Fri Dec 11, 2009 5:38 pm
by mikexgough
Have you checked to see if the other disc has a similar notch?........must say I have never seen discs like that before although I have seen some drilled and grooved faces.... I do stand to be enlightened if discs are available like that...

Re: Brake disc ok?

Posted: Fri Dec 11, 2009 5:46 pm
by munroman
Hi Donald, those discs look faulty and will have to be redone!





















Just kidding! :mrgreen: , what you are seeing there is where the disc has been balanced, its not an option to add weight like you do for tyres, instead it is machined off.
Perfectly fine, glad to hear that things have improved since fitting them.

Go and have a wee dram and relax!

Re: Brake disc ok?

Posted: Fri Dec 11, 2009 6:04 pm
by dandywarhol
WOW :shock: must've been helluva imbalanced - never seen that before.........

Re: Brake disc ok?

Posted: Fri Dec 11, 2009 7:32 pm
by rita
dandywarhol wrote:WOW :shock: must've been helluva imbalanced - never seen that before.........

Ditto

Re: Brake disc ok?

Posted: Fri Dec 11, 2009 8:46 pm
by francophile1947
Another "ditto" :? Guess all other discs I've had have been unbalanced - bit like me :lol: :lol:

Re: Brake disc ok?

Posted: Fri Dec 11, 2009 9:57 pm
by madmile
francophile1947 wrote:Another "ditto" :? Guess all other discs I've had have been unbalanced - bit like me :lol: :lol:

Or just better made in the first place :wink: .

Re: Brake disc ok?

Posted: Fri Dec 11, 2009 11:37 pm
by Diplomat
My first thought was that it might be some form of wear indicator but if so, when worn, it would start taking chunks out of the pads - or would it? After all, the Gruyere lookalike ones on motorbikes don't act like cheese graters.

Probably is for balance but the diameter of the discs is fairly insignificant compared to a wheel.



"must've been helluva imbalanced"

Perhaps the smaller the "wheel", the more compensation is needed.

Altogether an an interesting one. Hasn't it ever come up before?


Frank

Re: Brake disc ok?

Posted: Sat Dec 12, 2009 12:25 am
by dandywarhol
Usually the bigger the diameter the more the imbalance - centrifugal force and all that......................

Re: Brake disc ok?

Posted: Sat Dec 12, 2009 1:09 am
by The Great Pretender
Bloody Hell..........take them back........what happens when they wear down to the cutout and the pad digs in and locks up the wheel or rips the pads to shreads? :shock:

Re: Brake disc ok?

Posted: Sat Dec 12, 2009 12:34 pm
by eoptio
Hi

I recently fitted new discs on the back and they looked exactly the same, I thought it was a bit odd but fitted them anyway. Where did you get them from?

K

Re: Brake disc ok?

Posted: Sun Dec 13, 2009 1:33 am
by brorabongo
Evil bay.

Re: Brake disc ok?

Posted: Sun Dec 13, 2009 10:44 am
by mikeonb4c
I could just see a situation where product rejected by car manufacturing client as being outside casting tolerance is then 'made good' by grinding off until unit balances OK and then sold at suitable (lower than in-tolerance product) price. The m/cycle disc gruyere cheese theory doesn't really apply as thats lots of little holes much smaller than disc pad area whereas this (should the disc wea to that point) is 'one ruddy great pothole'. But I think that's academic as surely the disc couldn't (doesn't) wear down that much. The pads are the sacrificial element and the disc wear should be v. slow. My guess would be that the problem - if there is to be one - will be uneven heat distribution leading to local distortion. But if this were to happen then you'd know as you'd feel it on the braking / steering just as you did with the old ones.

My (uneducated) guess is they will be fine 8) [-o<

Re: Brake disc ok?

Posted: Sun Dec 13, 2009 11:35 am
by Diplomat
The pads are the sacrificial element and the disc wear should be v. slow.
That's what I have always thought, Mike. However, over the years I have read many a letter to motoring magazines complaining that an MOT tester has called for new discs. I often wondered if this was more to do with drumming up business than aything else but there have been suggestions that the composition of the "resin bonded fag ash" is now more abrasive than the old asbestos composition.

Your comment regarding heat distribution is interesting. I am a naughty boy and tend to sit with my foot on the brakes at lights etc. but have not knowingly been troubled by hot spots (or boiling brake fluid).

Luckily, as the Bongo has discs all round, the front ones don't do all the work and I have found that the pads last well, considering the weight of the vehicle.

Near my home there are several short sections of dual carriageway where the norm appears to be to accelerate like hell for the first third and then keep the brakes on for the last two thirds.

I always assume that these guys don't have to do their own pad replacement and could also be the ones writing to the mags about worn discs!

Re: Brake disc ok?

Posted: Sun Dec 13, 2009 11:44 am
by mikeonb4c
Diplomat wrote:
The pads are the sacrificial element and the disc wear should be v. slow.
That's what I have always thought, Mike. However, over the years I have read many a letter to motoring magazines complaining that an MOT tester has called for new discs. I often wondered if this was more to do with drumming up business than aything else but there have been suggestions that the composition of the "resin bonded fag ash" is now more abrasive than the old asbestos composition.

Your comment regarding heat distribution is interesting. I am a naughty boy and tend to sit with my foot on the brakes at lights etc. but have not knowingly been troubled by hot spots (or boiling brake fluid).

Luckily as the Bongo has discs all round the front ones don't do all the work and I have found that the pads last well, considering the weight of the vehicle.

Near my home there are several short sections of dual carriageway where the norm appears to be to accelerate like hell for the first third and then keep the brakes on for the last two thirds.

I always assume that these guys don't have to do their own pad replacement and could also be the ones writing to the mags about worn discs!
Yes, I know they do wear over a long enough period. I imagine is partly as you say (and maybe that will increase if/as materials going into pads is less well regulated), but also maybe due to scoring by other abrasives. Anyway it does happen.

We've had many on here say that the most likely cause of warped discs on Bongos is holding on the footbrake esp after hard braking. Interesting is so. I'm like you. I was trained to but handbrake on and go into neutral whenever I stop for any length of time. I don't do neutral except on short stops but I do still use the handbrake most times. Most of all, I use anticipation (like you) and engine braking a lot, in order to postpone the evil day when I'll next be changing my own brake pads. I've used HOLD regularly to brake since I got the Bongo, and I'm increasingly using HOLD and moving from D to S1 one (which often means virtually no use of brakes is needed) to do so.

Must admit, I totally love Bongos - they appeal to the kind of driver I am (not hurried, but no plodder, like torque, like good handling for the class, like character, like pilot workload low enough to enjoy my surroundings while driving, like it all on the cheap, like a piece of machinery I can fettle, etc. etc.)