JAP Disc and pad specs

[Phil Wall]

I am trying to sort out my high-speed brake judder problem i.e. last night’s 160mph brake check re ( Oakington thread). I have noticed a slight judder before when braking from about 125mph, but nothing like last night. At normal road speeds there is no problem.

 

On visual inspection the discs look OK, slight surface ridges on the fronts but nothing severe, pads are worn about half way down on the fronts and rears.

 

I want to measure the disc run out using a dial indicator gauge, does any one know the run out limits?

 

I will also check the disc thickness if some one can give me the max and min figures for Jap discs.

 

Minimum pad thickness would also be useful.

 

Can't fit my UK brake units I have wheels I can fit them into.

 

 

Any other suggestions re the judder would be most welcome.

 

[Guest Martin F]

 

Check lower ball joints as well.

 

I know that's a MKIII trait, but still worth checking.

 

 

[Phil Wall]

Would that have shown up on the MOT?

Just had one 3 / 4 weeks ago.

[Guest Martin F]

 

They should have been checked at the MOT, but i'm not sure how bad they would have to be to fail the MOT.

 

But my experience is they get worse very quickly with lots of heavy braking.

 

Check them by trying to lever the joint apart and see how much movement there is. Any more than a few mm and they should be replaced.

[Guest Ash]

 

 

Minimum pad-lining thicknes is 1 mm, standard is 11 mm.

 

Disc thickness is 32 mm, minimum thickness is 30 mm.

 

Disc runout is measured at a position of 10 mm in from the outside edge. Maximum runout is 0.05 mm.

 

Yours,

J

[Phil Wall]

Thanks Ash,

 

No flies on you up bright and early I see.:o

 

 

I will try the brute force approach on the lower ball joints, as recommended by Martin, then get technical.