Pad not sweeping whole face of disc

[Nucci]

Howdy all,

I just put new DBA slotted rotors and some RB74 pads on the front of my 200sx, after driving I had a quick check of the fronts to see if anything didnt look write, and on inspection I could see the very faint lines appearing over the top two thirds of the rotor, but the third of the rotor closest to the hub doesnt look to have been swept. What could be the probable causes of this, and what can I do to rectify the problem, will see if I can get some pics up soon.


Cheers :cool:

[Trevor@BDA]

How long have you had them in??
Trevor@BDA

[dattoman1000]

Does the pad have enough radial depth to cover the whole disc?
Some pads don't .
I think from memory the DB1199 RB74 is the one they use for this application. If so its actually a Landcruiser backing plate and might not have the same radial depth as the DB1170 Nissan equivelent.

[Trevor@BDA]

That is correct Dattoman............RB74 for that application is 1199
The sweep is fine and does not normally cause a problem with the 200SZ.
In fact if you trace the both pads using the locating pin holes as a reference, 1199 is about 5-6mm longer than 1170.
Sometimes these pads take a few days to settle into worn rotors, which is why I asked how long they had been in the car.
If they have been in for a while and still are not sitting on the inner part of the rotor there is some other reason
Regards
Trevor @ DBA

[Nucci]

Yes the rotors are as old as the pads (2 days old), the old 1170 pads that were on the car were chewed at both of the ends, so I guess they didnt fit the caliper too well. Is pressure always applied evenly over a pad from the pots on the caliper? I havent braked really hard as of yet and I was wondering if this could be the reason it isnt wearing closer to the hub.

[Trevor@BDA]

That's what I thought could be the problem.
The pads are still new and not bedded properly (yet).
Were the pads so badly worn that the new ones had to be fitted??
Or conversely were the rotors so badly worn that they needed changing??
We always bed the RB74s in using a written procedure which we send out with a new set of pads and would bed rotors and pads in separately with this compound.
They are pads which need bedding properly and that is over a set type of heat cycle. If you replaced the rotors at the same time you are probably still trying to bed the rotors in at town type speeds.
Even when bedding these pads as we do here they still sometimes take a few days to a week to settle flat onto the rotor surface - under road usage.
Trevor @ BDA

[Nucci]

Thanks for the help people!

Yes Trevor, the rotors were quite worn out, had resin deposits all over them and had quite a pronounced lip around the edge, instead of getting them machined I went the option of getting the slotted ones and putting them in, as far as the pads went, I changed them as like I said earlier they were chewed at the ends (they were 1170's) and I dont think they would of done me any favours on the track. Any special advice concering the RB74's and bedding, seeing as they have such a large working temp range? I suppose changing both pads and rotors at the same times does cause some grief, Im guessing the technique for bedding in rotors and pads can be conflicting at times.