Brake Judder

[NeilW]

Hi All,
After not using the old girl for about 6 weeks (while I sorted out a new exhaust) the brakes now judder/vibrate. The faster I go or harder I brake the more they do it. Definitely didn't do it before. I've had the pads out, checked the pistons for free movement, coppaslip'd everything, but no better. There are lots of threads about warped discs, but can this happen while the car is stood? Or is there a more likely culprit?

 

[Lemon]

Hi Neil Mine did this recently also after not being used for a few weeks. I had cleaned it before putting it away in the garage and it started raining before i put it away so was still slightly damp. A little bit of surface rust I am guessing was hiding somewhere around the back of the disc. It took miles and miles for it to free and i too thought my discs were warped. One minute I was about to book it into the garage for a look next thing it was smooth as butter, very weird. Of course it could be the discs warped but sounds very similair to my symptoms. I guess the mora for me is drive it more [][] Cheers Lee

 

[John Sims]

I would have thought it was unlikely the discs warped while sitting in the garage. The only slight possibility would be if you put it straight in to the garage after having thrashed it within an inch of its life getting the brakes nice and toasty. Because an area of the disc is covered by the pad, and the pads themselves are hot, this area of the disc will take longer to cool than the exposed disc. Lee's option is perhaps more likely. The disc will get uneven surface corrosion, again because of pad contact, and can introduce the effect of grooves at the edge of the pad while stationary for a long period. Like what Lee said - take it out for a good long thrashing and it should sort itself out.

 

[NeilW]

Thanks for the replies chaps, sounds a lot cheaper than throwing new parts at the problem. And a good excuse to put some miles on her this coming weekend.

 

[Hilux]

What tyres? Very soft compound can flatten over time and cars on it should be raised off the floors or the wheels rotated every now and again if stored static over long periods. Also, if you have locking wheel nuts made of steel and ally nuts on the remainder then always ensure the locking nut is opposite the valve to reduce/balance vibration [] and then let me know how you get on [] Wheels are balanced off the cars without wheel nuts so the effect (small thought it is) can be noticeable.

 

[John Sims]

ORIGINAL: Hilux What tyres? Very soft compound can flatten over time .....

A very pertinent point. Even standard tyres will do this and more so if the car is left with hot rubber after a good play. When I regularly flew from Stan's Shed I would drive there enthusiastically (Is there any other way?) and stick the car straight in the long stay Car Park off the dual carriageway feeder road - ie the tyres went from 70 mph [8|] to zero in no distance at all and then stood. Every time driving home, after no more than 48 hrs standing, the car would feel evil. It would cure its self by the time I got home.

 

[NeilW]

Thanks Paul & John, good points. Would a non-circular tyre show symptoms all the time or just under braking? My issue is vibration when pressing the brake pedal, car feels smooth the rest of the time. Re the locking nuts - can't remember, I know on the 964 one of the 5 lugs is painted with a red spot that should be opposite the valve, must check the '44.

 

[John Sims]

No, the tyre thing is pretty much constant but more noticeable at speed. Id it is only under braking I think it is a uneven disc surface as previously noted.