I bought a new brake disc could it be warped?

**The Pastor** · 17th February 2007, 20:33

Hello world.

I replaced my warped and worn front brake discs. I bought 2nd hand discs from a popular brake disc man (i'll leave his name out of this as mistakes can happen) who said that he put them on his machine and that they were good to go and garanteed them.

But now the pulsing and juddering is worse than before! Its really really bad.

When I apply the brakes lightly (not really slowing down at all) i can feel the lever move in and out quite noticeably. When I brake hard it judderds all over the show.

I have also recently gotten braided brake lines, could air in the brake lines cause this? (i have bleed the brakes but prehaps i didnt do it good enough?)

Are there any other causes for the pulsing and juddering other than warped discs? I used the same brake pads as on the old discs as they were no were near worn out.

Thanks for all your help

RM

**Ixion** · 17th February 2007, 20:40

Well, if he guaranteed them , send them back.

And if they're second hand they're not new, are they?

Other things can cause brake judder but 9 times out of 10 its warped disks.

WHY, oh WHY the manufacturers must make them out of such stupidly thin metal I do not know.

**The Pastor** · 17th February 2007, 21:06

Originally Posted by Ixion

Well, if he guaranteed them , send them back.

And if they're second hand they're not new, are they?

Other things can cause brake judder but 9 times out of 10 its warped disks.

WHY, oh WHY the manufacturers must make them out of such stupidly thin metal I do not know.

Could you give me somthings to check that could cause it to judder?

and there new to me...

Thanks

Rm

**Warr** · 17th February 2007, 21:30

Solid disc's or floaters ?

**Motu** · 17th February 2007, 21:52

I'd say you had some other problem.

New rotors warping is common - when I worked at a franchise dealer we used to machine rotors on new cars.From my research I've often come across automotive technicians insisting on machining new rotors after fitting.Most are made from cast iron and internal stresses put them out of true when fitted.

This is car rotors - bike rotors are different,but the same.....

**The Pastor** · 17th February 2007, 22:41

Originally Posted by Warr

Solid disc's or floaters ?

Solid

Originally Posted by Motu

I'd say you had some other problem.

New rotors warping is common - when I worked at a franchise dealer we used to machine rotors on new cars.From my research I've often come across automotive technicians insisting on machining new rotors after fitting.Most are made from cast iron and internal stresses put them out of true when fitted.

This is car rotors - bike rotors are different,but the same.....

Sorry, should of posted better these discs are 2nd hand disc's not new ones.

**imdying** · 17th February 2007, 23:35

Originally Posted by Motu

New rotors warping is common - when I worked at a franchise dealer we used to machine rotors on new cars.

Holden perchance? The Holden workshop guys could machine a set of rotors as fast as anyone else in this part of the world once upon a time... plenty of practice

**Pumba** · 17th February 2007, 23:58

If the discs have a garante then I would be talking to whoever sold them two you

**Warr** · 18th February 2007, 07:50

Originally Posted by renegade master

Solid

It is possible that the mounts are not true. I figured that using a dial guage and ended up taking the wheel to F1 Engineering in Hams.
Without a dial guage its pretty difficult to determine what is going on... appart from the obvious, judder !

**Motu** · 18th February 2007, 08:49

Originally Posted by imdying

Holden perchance?

Honda - a KwikWay brake lathe was part of the Honda service tools.First time I'd seen such a thing....and I'm talking 1987 here,this is not new,been a problem for decades.

You are complaing about 2nd hand rotors not being true? Why bother to even ask?

**The Pastor** · 18th February 2007, 08:49

Originally Posted by Warr

It is possible that the mounts are not true. I figured that using a dial guage and ended up taking the wheel to F1 Engineering in Hams.
Without a dial guage its pretty difficult to determine what is going on... appart from the obvious, judder !

Could you explain it a bit more?

The shop that sold them put a gauge on them and said they were true, I have no reason to belive otherwise. (if they sold warped discs they would go out of buissiness real quick)

But mistakes can happen.

Now this is what I want to know, could it be that the old brake pads somehow conformed to the old warped discs and now with the straight discs the pads are warped and give off that awefull juddering?

Cheers
RM

**megageoff76** · 18th February 2007, 09:36

I replaced the discs on my CBR400 once because they pulsed and juddered under braking. Fitting the new discs made no difference, as it turned out that it was a buckled front wheel/hub that was causing the problem.

Ridden over any potholes recently?

Might pay to check this.

**The Pastor** · 18th February 2007, 12:24

Originally Posted by megageoff76

I replaced the discs on my CBR400 once because they pulsed and juddered under braking. Fitting the new discs made no difference, as it turned out that it was a buckled front wheel/hub that was causing the problem.

Ridden over any potholes recently?

Might pay to check this.

Yeah just took her down to cycle treads (awesome that they are open on sundays, and today I actually got some customer service.) said to replace the wheel berings and overhaul the cailipers. I'll give that a go and see what happens!