Warped Brake Disk?????

jamiemacp · Post by **jamiemacp** » Sat Jan 12, 2008 12:12 pm

I am about to fit a new set of wheels, however since the Bongo was on a long run juts before Chritmas, I have been experiencing a pull on the steering wheel to the left. As you crawl along, the steering wheel pulls to the left slightly, and fairly strongly for every turn of the wheels, so the effect you get is a very rhythmic tug on the steering whee which turns into a shake at higher speed.
There was no reson for this to happen, nothing was knocked, it just appeared.
To me it feels like the left hand brake disk maybe warped and it is catching the barke pads at the same point at every turn of the left wheel and therefore "grabbing" it.
Has anyone any experince of this? either on a bongo or any other kind of vehicle?
Is it easy enoguh to change the disk? and can the Bongo disks be skimmed okay?
Cheers for any comments suggestions.
jamiemacp

dandywarhol · Post by **dandywarhol** » Sat Jan 12, 2008 2:14 pm

First try changing over the front wheels to make sure it's not a tyre/wheel related problem Jamie

Colin Lambert · Post by **Colin Lambert** » Sat Jan 12, 2008 2:46 pm

Press the pedal lightly whilst driving and if the pedal is 'pushed back' under your foot in a rhythmic fashion, you have one or two warped discs. Usually both go together. This is caused by braking hard and then stopping, say at traffic lights, and keeping your foot on the brake pedal instead of using the handbrake. This causes the discs to stay hot in the area of disc covered by the pad but cooled down round the rest of the circumference. This uneven cooling causes the disc to warp and it is much more common on ventilated discs.
I was going to offer to skim them for you but have just seen where you live!!
You need a tungsten carbide tipped tool to skim discs. Any good machine shop can do it for you but there is a minimum thickness below which one cannot skim them. This should be marked on the hub of the disc somewhere. There is not much tolerance on ventilated discs so if this does prove to be the problem you may be in for new discs. I suggest if this IS the case that you replace BOTH at the same time.
The should be very easy to remove as long as the have not rusted to the hub, in which case a large 'Irish screwdriver' may help!!.
Good luck.

jamiemacp · Post by **jamiemacp** » Tue Jan 15, 2008 2:34 pm

Well after taking the front wheels off and having a good poke about, I could find no obvious reason for the problem, so I went ahead and fitted new wheels and tyres at each corner. Hey presto, problem has completely gone and van drives like a dream.
Such a strange thing though as it came out of nowhere and was quite pronounced when driving at low speeds. old wheels and tyres have nothing obvious wrong with them either

Jamie

bigdaddycain · Post by **bigdaddycain** » Tue Jan 15, 2008 2:58 pm

Glad its sorted Jamie

Sometimes an old tyre's sidewall can start to break down somewhat,although they can be visually perfect,they can duplicate the impression of a wheel that is unbalanced,and the state of the tyre gradually worsens as time goes on...

Another good way of detecting a warped disc,(especially at this time of year) If your bongo has been stood around for a few days unused,you will notice that there is a slight build up of rust on the brake discs. Drive the bongo at tickover speed in drive for 20 0r 30 feet,knock her into neutral,and let her coast to a stop (without braking). Then visually inspect the rust on the discs, if its been quite uniformly sweeped, this indicates that the discs are pretty straight,if however, one part of the disc has a more noticeable amount of rust deposits than the rest of the disc,then it may indicate that the disc is warped, or warping.