I had the Scoobysport GroupN/Pagid/Briaided Hoses/fluid package just under a year ago on my MY95 UK Saloon. Coming back from LeMans and "Making progress" through the traffic. A few heavy stops to fit back into traffic and I started to get a fairly bad vibration under braking. Ooops I thought - I've warped the discs. However later (and still now) it seems to be nowhere near as bad but there is definately still a small vibration.

Can discs give a worse vibration when hot ? If I push them again will it come back ? Would this be covered under the disc warranty ?

Thanks

Deano

 

Sounds to me like you had uneven deposit of brake pad material on the disc after your drive. Did you go from 'making progress' to stationary in traffic (ie stationary whilst brakes were very hot still)?
This feels like warped discs when it gets hot, but goes away when cold. Following the bedding in procedures again usually gets rid of the problem - at least it did on my brakes.
Chuck

 

Chuckster

There were several "very hot" to stationary moments. I also had a lot of weight in the car (generator for the telly ) so brakes probably had their worst ever hammering (I don't do track days). I'll wip the wheels off later and have a good luck then follow the bedding in again.

Deano

 

Deano

It may be warping or it may be pad residue.

If you do a big stop, its best to leave a gap to the car in front and then creep into this gap over the next 30 seconds.

The discs can go red hot and either boil the pad resin which then cools onto the disc face, in a pad shaped blob, or most of the disc cools down but the bit under the pads is insulated from the air and remains very hot. This creates massive stresses in the disc and warps it.

There isn't a disc in the world that can cope with this sort of treatment.

 

Pete

Thanks for the info. Unfortunately some of the gaps had no more than a cars length or so. When everyone is trying to do the same thing the traffic was bunching very badly. The vibration is almost non-existant now but....

Get the ABS warning light staying on. Is there an easy way to check why ? or is it off to the Dealer.

For ages now (even before the brake upgrade) the first push on the pedal is much longer then it is subsequently. Requiring almost a "double tap" approach before roundabouts. It doesn't usually bother me (Its second nature now) but again pushing hard reminded me that it was something I really should get sorted. Any ideas ?

Deano

 

Hi Deano

There are other things happening here.

If you are getting lots of pad knock off (the reason why the pedal has to be pressed more occasionally) its almost certain that you have a wheel bearing problem. Excess play in the bearing is allowing the disc to press against the pads, pushing the pistons into the caliper. The displaced brake fluid gets pushed back up into the master cyclinder.

When you next press the brake pedal, a lot of the travel (or even all of it, in some cases) is used to re-flood the caliper pistons, before there is enough there to press the pads against the disc. It can be very scary when it first happens, if you aren't expecting it. It can happen with standard brakes when their heat turns the hub grease to liquid or even boils it, as this grease plays a part in taking up tolerance in the bearing.

Another symptom of failed wheel bearings is juddering brakes. This is because the bearings are now smaller and the race gets bunched up rather than being evenly spaced. Under heavy load, such as when braking, the gap between the ball bearings can rotate round and it gives the effect of having a flat spotted tyre. This will also damage the disc as it creates hot spots and stress points.

With your abs light, it may be one of two things. Either it is actually the handbrake/brake fluid light and this indicates that the fluid level is low, or if it is the abs light, the movement of the hub may have allowed the abs tone ring to hit the end of the sensor. The end of the sensor can break off or get bent when this happens, stopping that sensor counting the tone wheel teeth and registering a fault.

Worth getting it all checked out.

 

Funny you should mention wheel bearings......I get a high pitched squeel going round some corners and I was just turning the possiblity over in my mind this morning. If its been like that for a while I really really hope I havent caused extra damage. It only had a service (cam-belt) 4 days before LeMans but they didnt say anything.

So Next question .....

Would ScoobySport like to quote for a brake checkup and/or Wheel bearing replacement (via e-mail to dean.smith@idl-bt.com if you prefer to take it off-line)

Many Thanks for the info - its appreciated.

Deano