[ds968]

I clearly have glazed brakes because there is no way pads would last as long as mine have , and also leave no trace of any wear on the rotors ; the pads still have over 50 % left after about 60 K miles driven on them, and the rotors are like a mirror , no lip whatsoever, and no visible traces of lines, much less any grooves on the surface, after 115 K miles ( they are the original discs ) . So what's the problem you ask ?

Well, I keep hearing that the brakes must be glazed and if so, that significantly compromises stopping , obviously something which concerns me , but the car stops perfectly fine ! Both on soft or hard braking form high highway speeds, as well as normal street braking , again hard or soft and without any squealing , squeaking , etc. Just nice and quiet and it " stops on a dime ". So is it maybe just a deceitful seat of the pants assessment and in reality the actual stopping distance may be materially longer than it would be with new brakes on ? Not sure what to do ..

Partial Post: Please Login or Register to read the full post.

[MCL968]

Do nothing. Brakes work, there's no problem.

Partial Post: Please Login or Register to read the full post.

[oppositelock]

If it ain't broke, don't fix it. A major player in brake wear in driving style. Yours is light on the brakes, enjoy it.

Partial Post: Please Login or Register to read the full post.

[ds968]

Sounds good . Maybe it's just that - I typically use the gears ( stick shift ) to " brake " much more so than I use the brake brake pedal so that could explain the longevity ..

Partial Post: Please Login or Register to read the full post.

[Rap]

You could measure the rotor to see how much is left on it. Not suggesting cutting it but if you compare it to cutting guidelines you could see how much is left to cut. Sometimes rotors wear well but still aren’t the same thickness as new. That would give you an indication. No lip after all those miles is unusual.

Partial Post: Please Login or Register to read the full post.

[J.Elenbaas]

Brake problems come in slowly, so hard to notice if they still work as they should.

Is the ABS still working when braking hard?

Partial Post: Please Login or Register to read the full post.

[ds968]

I may have used the term "hard" braking too loosely ; I applied the brakes very firmly, but just not stomped on them so hard so as to trigger the ABS. For that matter I don't recall EVER having activated the ABS in the 968 , so maybe I need to do that to see if the system even works ..


I'll measure the discs later today ..how thick are new rotors supposed to be ?

Partial Post: Please Login or Register to read the full post.

[Waylander]

We should all test the abs regularly


Grass or gravel or even wet roads

Partial Post: Please Login or Register to read the full post.

[J.Elenbaas]

Best to test on dry tarmac, with plenty of grip.

If you can get the ABS to work, the brakes work perfectly fine.

 

This also helps to get the glaze of the brake pads, resulting in a better bite from the pads on the discs.

 

The glaze comes on when using the brakes in normal traffic, thus not braking very hard every time.

So sometimes a few good brake excercises can take away the glaze from the pads.

Partial Post: Please Login or Register to read the full post.

[Rap]

I will need to look that up and I don’t have the Manual here. Do your rotors provide that info?

Partial Post: Please Login or Register to read the full post.

[J.Elenbaas]

Which info Rap? if the ABS is still working?

This you will feel once activated, only need good brakes for this.

Partial Post: Please Login or Register to read the full post.

[Rap]

His problem is glazing not performance. Inspections include checking rotors. I’m just suggesting trying to eliminate any width considerations. Pads sound good or at least his visual of them are.

Partial Post: Please Login or Register to read the full post.

[ds968]

I was trying to find out how many mm ( thickness ) a new OE 968 rotor is, but I don't see that info anywhere ..

Partial Post: Please Login or Register to read the full post.

[J.Elenbaas]

I found the thickness in the manual i have on page 397, but this is not from new discs

Min. brake disc thickness, after refacing

front   26.6mm (30.6mm M030), wear limit is 26mm (36mm M030) 

rear    22.6mm, wear limit 22mm

 

For the 944 S2 you will find the same limits as for the 968, only here you find the new discs thickness.

front    28mm

rear     24mm

 

@ Rap,

Yeah i know what his problem is, and that it is very strange not to have any groves or marks on his discs. (very smooth braker????  )

But when your pads are glazed it's very hard to get the ABS triggered.

When glazed you can brake it off by hard braking a few times, and you will notice the difference.

If you will never get your ABS triggered, you know there is a problem in the braking area due to underperformance of not blocking the tires on the tarmac.

 

I'm used to perform some emercengy brakings at least once a year, just before i have to go to the compulsory yearly car test.

Partial Post: Please Login or Register to read the full post.

[Waylander]

Dan 

from the Pagid online Brakebook www.brakebook.com

 

Brake Disc Type:Internally Vented; Diameter [mm]:298; Brake Disc Thickness [mm]:28; Height [mm]:74; Hole Arrangement / Number:05/09; Supplementary Article/Info 2:without wheel hub / without wheel studs; Surface:Coated

 

in the manual

min thickness for wear 26.0mm

min thickness after resurface 26.2mm

 

so a huge 2mm to play with from new

 

must have posted that at the same time

Partial Post: Please Login or Register to read the full post.

[ds968]

Thanks everyone - I'll measure the rotors and then practice a couple of emergency braking maneuvers to test the system. It would be weird if the discs thickness has worn down without the formation of any lip whatsoever, but I suppose anything is possible .. But absolutely zero grooves, in fact to even see hair-thin circular lines on the surface you'd have to have really, really good eyesight ;-) :-) . I need reading glasses to detect them :-)

PS - my discs are not crossed-drilled, just the regular ones. ( I'm not even sure if there was an option for OE ventilated / drilled discs for the 968 when these cars were produced ...was there ? )

Partial Post: Please Login or Register to read the full post.

[Waylander]

yes the M030 ones were drilled i think

Partial Post: Please Login or Register to read the full post.

[J.Elenbaas]

Yepp, the M030 ones are the drilled ones, not sure if they fit the normal 968's.

Partial Post: Please Login or Register to read the full post.

[Waylander]

Yes they do if you had the 5k factory option M030 package


I have just rebuilt a set of M030 callipers for a friend, you can still buy them from Porsche @ £1200.00 each

Partial Post: Please Login or Register to read the full post.

[ds968]

Setting aside my ( arguably glazed ) 968 brake pads , we had our 2014 Jeep Grand Cherokee recently at the dealer for an emissions recall software fix, and in typicall dealer fashion they tell you everything that's "overdue" on your car which really needs maintenance. So they gave me a laundry list of about ten items, but surprisingly brakes were not on that list . I asked them if they checked the brakes, and they said " yes, we did and they're ok, so you don't need to worry about them for maybe another 10 K miles or so. " ) .

Here's the kicker : we logged 68,400 miles on the original brake PADS and they're still " ok " ? WTF ?! Today, I took the car to an independent shop for some other basic maintenance stuff for which I don't want to pay dealer prices and I asked them as well to look into whether or not I need brakes. They said that the brakes still have enough left on them so I should not be concerned until the warning light comes on . This is a medium-large heavy SUV and I'd think the brakes take a beating , although it's driven 80 % highway and 20 % street , but 68 K miles on the original pads and still a decent amount of life left on them ?! I'm shocked. Maybe my 968 pads are not glazed after all and the average life of brakes are over 75 K miles unless you track the car ?

Partial Post: Please Login or Register to read the full post.