Bongo Fury

I changed all my brake pads on Sunday. This is the first time I'd done the front pads, and I was intrgiued to see the the pads working on the inboard disc, on both front wheels, were much more worn/stepped/ridged on the portion that contacts with the outer portin of the disc. On examination, I found that the inboard discs do not have their surfaces milled smooth as far out as the outboard discs, whereas the pads are all the same shape and seem to assume they would be. Oh well thought I, they've worked fine as they were, so just carry on.

The practical consequence of this was that when I test drove the vehicle afterwards, I could feel a very strange sensation through the brake pedal for the first few hundred hards and until the new pads working the inboard discs had the excess material ground off them by the rusty unmilled outer portion of the discs.

So the big question is: is this normal, or should all my front discs be milled out the same distance from their centres. And if it isn't normal, how on earth did the discs get like that.

Everything seems to work fine, so I'm not fussed, but it does seems like a little braking efficiency is maybe being lost. But maybe this is some weird way of giving early warning of brake pads being worn out (i.e. once the main face wears to match the graunched bit, the driver will start to feel a graunching through the pedal as the pad is forced to work the unmilled portion of disc). But no, this can't be, as the rear pads/discs had no such problem.

Hi
Mike
Not quite sure what you're trying to say, but it sounds like the edge of the disc is raised proud of the rest of the surface...if this is the case, then the discs are worn down. Probably some pads contact a smaller area and wear them. The answer , if this IS what you describe, is to get the discs skimmed, or get some new ones. They're not very dear, and can be had from the Club Shop, from what I remember!
Cheers
Helen

helen&tony wrote:Hi
Mike
Not quite sure what you're trying to say, but it sounds like the edge of the disc is raised proud of the rest of the surface...if this is the case, then the discs are worn down. Probably some pads contact a smaller area and wear them. The answer , if this IS what you describe, is to get the discs skimmed, or get some new ones. They're not very dear, and can be had from the Club Shop, from what I remember!
Cheers
Helen

They are proud, but not significantly, and due really to expansion cause by rusting of the unused portion. Do you think perhaps that some time in the past, pads with a smaller bearing area had been fitted, and then new pads were fitted that had a larger bearing area. This meant that they were bearing on to the now rusted section of the discs. But even so, why only the inboard disc faces?

Not really fussed about taking action. Brakes are working plenty good enough, and cash and time are in short supply just now

Hi Mike
I haven't stripped the Bongo brakes, but some calipers "float", and the actuated pistons are only on one surface, so the pad on that side pushes against the disc, and pulls the caliper over with a fixed pad on the other side. I suspect the Bongo isn't like that, and has a piston or 2 pistons each side...but not having stripped one, I can't say...it's just as cheap and effort saving to just get them done ...anyway, some brakes just seem to wear on one side more?...Personally, I had the discs replaced, but I have in the past done as you suggest...bung new pads on and let them wear a groove ...as long as they stop you!!!!!
Cheers
Helen

helen&tony wrote:Hi Mike
I haven't stripped the Bongo brakes, but some calipers "float", and the actuated pistons are only on one surface, so the pad on that side pushes against the disc, and pulls the caliper over with a fixed pad on the other side. I suspect the Bongo isn't like that, and has a piston or 2 pistons each side...but not having stripped one, I can't say...it's just as cheap and effort saving to just get them done ...anyway, some brakes just seem to wear on one side more?...Personally, I had the discs replaced, but I have in the past done as you suggest...bung new pads on and let them wear a groove ...as long as they stop you!!!!!
Cheers
Helen

Bongo only has pistons on one side of the caliper: two pistons on front calipers, one piston on rear calipers. yes its a bit weird and if I had time and money I'd love to get my brakes looking and working like BigDaddycains. But they are fit for purpose and my Bongo is a working car like yours, so I'll settle for dreaming etc.

Mike, Helen is correct in saying that the calipers are the floating type.
If the pads on either side are worn significantly differently then the odds are that that the floating mechanism is sticking. In really bad cases this can seize up and the pad will only contact the disc on one side forcing the disc to try to bend and possibly even break. It can also cause the pads not to move back off the disc making the brakes stick on, again in extreme cases this heats up the brake fluid and you lose brakes.
Doesn't sound like yours are that bad though but I would certainly check that the calipers are free to move on the slides, probably are otherwise you wouldn't have got the new pads in.
The other thing to check is the thickness of the disc, according to the manual it says the limit is 26mm. If they get too thin they eventually break under pressure from the pads when the brakes are applied. Remember the discs are vented so not solid metal all through the thickness so if the ridges are more than a few mm odds are they need replacing.

I replaced my discs last week as I was getting a slight but annoying wobble on braking - a sure sign of a warped disk.

On stripping the O/S caliper I could see why the disk had a wee warp to it. The lower slide was quite well seized. Upper was free. So much so that the inner pad was tapered due to the uneven wear. Clearly the caliper wasn't floating back open causing brake drag, and overheated the disk. N/S was also affected, but not as badly.

Slides cleaned and re-assembled with plenty of grease and new disks/pads both sides and my brakes not only don't wobble any more, they are miles more powerful. It's amazing how you don't notice the gradual reduction in braking.

Taligaters beware, this van can now stop!

I'm on the case with all that, guys. They are indeed floating calipers (with pistons on one side only), and they are floating just fine, and I've treated them (the slider bolts) to a little coppaslip (as I did last time I did the rears) to make sure they stay that way. there is no judder, no warping, everything works fine, and brakes are powerful. Its just that for some reason a small portion of the inner pads on the front discs are having to run over what is either unmilled or corroded disc surface. It doesn't matter - they get ground to match the surface very soon after being put into service. But I wonder how the situation has arisen.

All I can think is that some time in the past either a set of pads was fitted with a smaller pad on the inner / piston side than the outer side, allowing that bit of the disk face to build up the corrosion - or at some point a set of pads has been used right down to the metal and ground that area first for some reason.

dave_aber wrote:All I can think is that some time in the past either a set of pads was fitted with a smaller pad on the inner / piston side than the outer side, allowing that bit of the disk face to build up the corrosion - or at some point a set of pads has been used right down to the metal and ground that area first for some reason.

That's all I can think it is. I notice that different brands of Bongo pads do seem to differ a bit anyway, and maybe mechanics fit 'compatible' parts to grey imports if they can't get the kosher part number off the motor factors database.

Hi mikeonb4c,

The normal practice when replacing pads is to dress the discs or replace,I Would imagine that is what Adrian would do if he had done the work for you.

rita wrote:Hi mikeonb4c,

The normal practice when replacing pads is to dress the discs or replace,I Would imagine that is what Adrian would do if he had done the work for you.

Thanks Rita. Take your point but I afford running a Bongo by doing as much as I can for myself and evaluating each situation. The brakes are working very well as is (and were before new pads were fitted) so I think dressing / new discs would be a nice to do, but not really needed. The pads dressed themselves to the discs very quickly

mikeonb4c wrote:

rita wrote:Hi mikeonb4c,

The normal practice when replacing pads is to dress the discs or replace,I Would imagine that is what Adrian would do if he had done the work for you.

Thanks Rita. Take your point but I afford running a Bongo by doing as much as I can for myself and evaluating each situation. The brakes are working very well as is (and were before new pads were fitted) so I think dressing / new discs would be a nice to do, but not really needed. The pads dressed themselves to the discs very quickly

Great stuff I think I heard them in Scotland...

Just changed my discs and pads and mine were the same, due to the pads not sliding evenly in the calipers. I wouldnt worry about it if they work ok, just keep the slides lubricated every once in a while. its also worth winding the pistons back in and out a few times to make sure they are not sticking.

dave_aber wrote:All I can think is that some time in the past either a set of pads was fitted with a smaller pad on the inner / piston side than the outer side, allowing that bit of the disk face to build up the corrosion - or at some point a set of pads has been used right down to the metal and ground that area first for some reason.

Yep I would go with that...... I tend to go for Allied Nippon brand..... who make the pads for Mazda,Toyota,Nissan,Lexus,Mitsubushi & Brembo among others..... Normally I dress up discs it they are okay that is..... a decent clean up of all the brake components blow out with the air line & re-grease on assembly on the parts that require it and there you go...... an extra 10 mins each side....attention to detail....