Surprise! - Rear pads have worn more than the fronts
- Thread starter Ian964
- Start date
Jeff,
My car does not exhibit much difference between front and rear pad wear. I have 340mm 6 piston 991 calipers and discs at the front and stock Cayman S rear and use OEM discs and pads. I poke out the drilled holes after each track day.
First set of front pads replaced at 4mm after 6.6k miles and rears at 3mm after 8.2k miles
Discs, fronts lasted 10.2k miles and rears 13.2k miles
These wear rates seem constant, aside from the brake pedal bush debacle.
Maybe I don't drive hard enough.
This tool is useful for easy checking of pad depth
https://www.amazon.co.uk/gp/product/B00J06OCEK/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
Ralph
My car does not exhibit much difference between front and rear pad wear. I have 340mm 6 piston 991 calipers and discs at the front and stock Cayman S rear and use OEM discs and pads. I poke out the drilled holes after each track day.
First set of front pads replaced at 4mm after 6.6k miles and rears at 3mm after 8.2k miles
Discs, fronts lasted 10.2k miles and rears 13.2k miles
These wear rates seem constant, aside from the brake pedal bush debacle.
Maybe I don't drive hard enough.
This tool is useful for easy checking of pad depth
https://www.amazon.co.uk/gp/product/B00J06OCEK/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
Ralph
My 987.2 CS has covered just over 21k miles and when I had the wheels off recently I noted that although the front pads had about 8mm left the rears were down to about 5mm. The mileage has included about 6 track days, so the wear appears to be very reasonable to me.
My past experience (admittedly with FWD cars) has always been that the front pads wear faster than the rears - which is what you'd expect because of the forward weight transfer during braking - so I'm puzzled to understand why this has occurred.
Maybe there's a fault with the rear brake proportioning valve (assuming modern Porsches still have such a device) or perhaps the PSM has been over-active controlling understeer during my stints on track, although I have to say that I've never noticed it kicking-in and the 987.2-series cars don't feature PTV as far as I can recall. My other thought is that with the mid-engined car's rear weight bias more rear wheel braking is required than with a FWD car.
Your comments and/or similar experiences would be appreciated.
Jeff
My past experience (admittedly with FWD cars) has always been that the front pads wear faster than the rears - which is what you'd expect because of the forward weight transfer during braking - so I'm puzzled to understand why this has occurred.
Maybe there's a fault with the rear brake proportioning valve (assuming modern Porsches still have such a device) or perhaps the PSM has been over-active controlling understeer during my stints on track, although I have to say that I've never noticed it kicking-in and the 987.2-series cars don't feature PTV as far as I can recall. My other thought is that with the mid-engined car's rear weight bias more rear wheel braking is required than with a FWD car.
Your comments and/or similar experiences would be appreciated.
Jeff
Ian964 said:
Ian,
Do you find the PSM dash light flashing under those conditions?
pterri
New member
Quiet common i understand, mine does exactly the same. Yes i think its the PSM kicking in, it must do it quiet gently as never really notice it except on a few occasions when it clearly saved me from a spin.
By the way, i spoke to a Porsche Silverstone instructor at Rockingham (he'd been hired by a wealthy chap for a whole days tuition). He said that you really shouldn't need to turn it off if your driving smoothly on track. I'm clearly not!
I'm just glad its so easy to change pads on these, save a fortune. The longest job it digging the jack out and getting the wheels off.
By the way, i spoke to a Porsche Silverstone instructor at Rockingham (he'd been hired by a wealthy chap for a whole days tuition). He said that you really shouldn't need to turn it off if your driving smoothly on track. I'm clearly not!
I'm just glad its so easy to change pads on these, save a fortune. The longest job it digging the jack out and getting the wheels off.
drive PSM off all the time, that's sorts it. eps on track days 
while it's not PTV is does still brake the rears a bit :-( not to help you in the bends like PTV , it seems to cut in out the bends to stop you spinning.
driving smoother does help but it's a yaw angle/steering/throttle input thing, it's bloody annoying but I only see to get it on the odd bend.
while it's not PTV is does still brake the rears a bit :-( not to help you in the bends like PTV , it seems to cut in out the bends to stop you spinning.
driving smoother does help but it's a yaw angle/steering/throttle input thing, it's bloody annoying but I only see to get it on the odd bend.
Jeff,
Just to ask the obvious question, have you measured or know the new pad material depth?
These below are quite thick for endurance racing..
Ralph
Just to ask the obvious question, have you measured or know the new pad material depth?
These below are quite thick for endurance racing..
Ralph
Many thanks all for your responses. Good to hear that I'm not the only one experiencing this.
Ralph, oddly enough I've never seen the PSM light flashing, which is rather puzzling since the damned light is always flashing on my Mk5 Golf GTi - and I can always feel the SM operating..! As Pete says, I have the feeling that the Cayman setup is both much less intrusive and softer. Maybe I should summon up the courage to switch off the electronic governance at my next track day - watch this space..!
I don't know the exact original pad thickness but my guess is that it's at least 10mm, probably 12mm, based on the mileage I've done on the set. The backing plate is about 5mm so that endurance pad must be about 15mm.
Just to add that I've been quoted a hefty £440 (£305/£135 for parts/labour) by the PC to replace the rear pads. Hmmm...I think it's time to get the tools out again or to contact my nearest friendly Indie.
Cheers,
Jeff
Ralph, oddly enough I've never seen the PSM light flashing, which is rather puzzling since the damned light is always flashing on my Mk5 Golf GTi - and I can always feel the SM operating..! As Pete says, I have the feeling that the Cayman setup is both much less intrusive and softer. Maybe I should summon up the courage to switch off the electronic governance at my next track day - watch this space..!
I don't know the exact original pad thickness but my guess is that it's at least 10mm, probably 12mm, based on the mileage I've done on the set. The backing plate is about 5mm so that endurance pad must be about 15mm.
Just to add that I've been quoted a hefty £440 (£305/£135 for parts/labour) by the PC to replace the rear pads. Hmmm...I think it's time to get the tools out again or to contact my nearest friendly Indie.
Cheers,
Jeff
pterri
New member
That's outrageous, even without a ramps its a 20 min job. You need some small needle nose pliers to pull the cotter pin out and a bunch or old screwdriver to push out the retaining pin. really is the simplest of jobs. No handbrake adjustment needed. You tube is your friend, lots of guides on there.
Agreed Pete.
I think they replace everything - pads, dampers, retaining pins, cotter pins, wear sensors and spring retainers - which would account for the high parts cost. £135 will cover an hour's Forever Porsche discounted labour.
My local Indie is asking less than £150 for the job, including a 15% PCGB discount, using Porsche pads and wear sensors and Pagid dampers. As you say, there are plenty of online guides if I want to do the job myself.
Jeff
I think they replace everything - pads, dampers, retaining pins, cotter pins, wear sensors and spring retainers - which would account for the high parts cost. £135 will cover an hour's Forever Porsche discounted labour.
My local Indie is asking less than £150 for the job, including a 15% PCGB discount, using Porsche pads and wear sensors and Pagid dampers. As you say, there are plenty of online guides if I want to do the job myself.
Jeff
Brian_Innes
Member
Jeff,
I also had rear brake pad wear issues with my Cayman R when I was competing in motorsport hill climbs and sprints. I always switched off the PSM, but the yellow PSM dash light kept flashing on tight, high G-force corners regardless, which indicated that the brakes were being activated.
I replaced the brake pads front and rear myself. It's an easy job to do.
Brian
I also had rear brake pad wear issues with my Cayman R when I was competing in motorsport hill climbs and sprints. I always switched off the PSM, but the yellow PSM dash light kept flashing on tight, high G-force corners regardless, which indicated that the brakes were being activated.
I replaced the brake pads front and rear myself. It's an easy job to do.
Brian
Had it through Radillion as the rear gets light but not at slower corners, maybe wider wheels make for better traction.
Kevan,
It is probably unreasonable to expect men on a forum to look at FAQs first []
So Jeff's fronts are actually wearing faster than the rears, given he has 3mm less at rear, yet started with 4mm less?
I do have a question though, are the measurements in the FAQ pad + backing plate?
Ralph
It is probably unreasonable to expect men on a forum to look at FAQs first [
] So Jeff's fronts are actually wearing faster than the rears, given he has 3mm less at rear, yet started with 4mm less?
I do have a question though, are the measurements in the FAQ pad + backing plate?
Ralph
Ralph,
To be honest I got them from a spreadsheet on line and so cannot be totally sure of the measurement datum used, however, I was told at JAZ that the original pads are Textar and that the discs are made by Sebro but without the Porsche marking on them otherwise indistinguishable. From memory I think Design 911 offer kits of discs and pads or individual items as per OEM or alternatives, for those concerned about warranty and wanting to get OEM from Porsche then always remember the discount! They are easy to replace ( as someone said thanks You Tube ) and if changing before reaching the wear pads then it should be possible to reuse those too. I have known it where some have reused the old dampers although they are usually stuck to the pad when it comes to removal but I can't say if that just happens through being pressed together over time or if they actually use adhesive, I would hope the former.
To be honest I got them from a spreadsheet on line and so cannot be totally sure of the measurement datum used, however, I was told at JAZ that the original pads are Textar and that the discs are made by Sebro but without the Porsche marking on them otherwise indistinguishable. From memory I think Design 911 offer kits of discs and pads or individual items as per OEM or alternatives, for those concerned about warranty and wanting to get OEM from Porsche then always remember the discount! They are easy to replace ( as someone said thanks You Tube ) and if changing before reaching the wear pads then it should be possible to reuse those too. I have known it where some have reused the old dampers although they are usually stuck to the pad when it comes to removal but I can't say if that just happens through being pressed together over time or if they actually use adhesive, I would hope the former.
Thanks Kevan, Ralph,
Am I'm missing something here?
I did actually look in the FAQs (surprise, surprise!) but all I could find was Disc Bakes and Pads which only mentions disc wear not pad wear. The discs look OK but I don't know the original front/rear pad thickness. I assume that they're the same and if so then the rear wear rate certainly is higher than the front.
Jeff
Am I'm missing something here?
I did actually look in the FAQs (surprise, surprise!) but all I could find was Disc Bakes and Pads which only mentions disc wear not pad wear. The discs look OK but I don't know the original front/rear pad thickness. I assume that they're the same and if so then the rear wear rate certainly is higher than the front.
Jeff
Jeff,
No you are not, I was []
No you are not, I was [
]
If I later found conflicting info I may have deleted some data but I just went online to Eurocarparts and their data shows that pad thickness is 15,5mm rear and 17,0mm front on the Textar pads, I'm presuming that this is an overall dimension.
This would show that if Jeff's pads are 2mm thinner on the rear the overall wear front to rear isn't far off being equal.
This would show that if Jeff's pads are 2mm thinner on the rear the overall wear front to rear isn't far off being equal.
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