Hi All,

Don't have a GT3 but a 2006 C2S that I retrofitted GT3 calipers on.......thought it might be more appropriate to post here since I've seen a few posts about pads knocking about in the GT3 forums

Scenario, retrofitted a set of six piston GT3/2 calipers on my C2S, all seems to brake fine but I have this knocking now when either coming to a slow stopped or backing out of the driveway, from what I've read seems slightly common

The calipers were rebuilt with new pistons/seals and new Porsche caliper hardware (center pin and spring), using Hawk HPS pads, double checked the pad part number and they seem correct after some research, clearly the knocking started after the retrofit and coming from the front.........

I did not use the Porsche pad dampers, after reading didn't seem all that important just coated the back of the pad with a thin coat of ceramic brake paste

If the pad is knocking around front to back and that's a question......should I add back the dampers or maybe some anti-squeal adhesive to hold/cushion the pad from moving??????

Thanks in advance for any insights

 

did you check your rotor runout? wheel bearings could be bad

 

New rotors but know what you mean about the bearing play, didn't thin about that, the C2S has 39k on it and the knock started after the caliper retrofit, not discounting your recommendation, good insight

Not hearing any groan at speed, have run it to 80 and very smooth, just seems pulling to a stop or backing up, I hear the "knock". I have had a knock in the right front suspension for a while (maybe strut mounts), maybe it's gotten worse......

 

I have the same. Have had time to diagnose but my initial thought it a loose ceramic puck. Was going to try retainer clips as a first step but will be watching this thread with interest.

 

New pistons with pucks in my case (all 12), unless something went wrong when I installed them or cracked afterward........was just thinking about the forward/backward movement and wondering if it's the Thrust/Wishbone arm, seems that would take the load front to back, only becoming more apparent with the extra brake force....or exacerbated it with letting the suspension drop while working on it, it almost sounds like "pop" now when the underpinnings get warmed up (summer heat)???

I know I need to get underneath it.........but I don't have a lift (i.e suspension setting/weighted to check)

Good thing is I have a set of control arms and thrust arms left over from my 2007 Boxster, new........that I never installed

 

Last comment, seems a bit more severe than pads moving to me...................maybe I'm a wimp............with noises

 

I have this same knock when reversing out of the driveway. My car is going to the dealer (it’s CPOd) on Friday, and I will ask them to look at this issue as well. Will let you know what they say.

 

That would fantastic!

 

I recently had this on my 997TT. It's the missing vibration dampers - - there are 6 of them per caliper that stick to the back of the pads and locate them in the center bores of the pistons. My car is much quieter with the dampers installed. No more knock when reversing or on harsh bumps.

If you track and change pads frequently, I can see why they get left off as the dampers require the calipers to be removed for a pad change. But for a daily/non track driver, I'd recommend using the dampers.

 

Thank you, the dampers make sense, I did not install them......I’ll get a set ordered. Does anyone know the piston sizes, if I remember there are 3 unique sizes in each caliper?

 

Front piston sizes. 28mm, 32mm, 38mm, it looks like.

https://racingbrake.com/caliper-rebu...orsche/bp-605p

Rear piston sizes. 34mm.

https://racingbrake.com/caliper-rebu...orsche/bp-408p

 

This also lists all of the overall specs for each type of caliper.

https://racingbrake.com/997-1-2005-08/

 

The pistons are different sizes, but all the dampeners for the 6-piston calipers are the same. Here's a link to what you need (no affiliation): https://www.pelicanparts.com/More_In...=0961&DID=9184

Shop around, you need 12 of those things. I think you can find them for less $10/ea.

 

Dealer wasn't able to replicate the noise. Oh well, will see if keeps happening.

 

DANGIT! I have my whole front end apart right now so going to check and see if the ceramic pucks being loose are causing this issue for me. May buy some puck clips if there are some loose pucks to see if that helps since its only happening on one wheel since the rebuild.