[M3SQRD]

Originally Posted by ZM2

Hmm, 17mm or 18mm works on my 9660 378x36mm front setup, but maybe the 18mm worked bc my disc was slightly worn?

Gotcha on the PRD. I guess the larger pad just helps with lifespan, which isn’t a huge concern on the rear?

Is the bias impacted that much bn 7767 49mm & 7766 43mm?

Thanks!

I can’t comment on the 9660 caliper but the 9668 with a 25 mm fits tightly on a 34 mm thick rotor. Perhaps the 9660 has extra pad clearance on a 30 mm thick rotor. However, the Cobalt 20 mm thick pad may cause a problem with a 34 mm thick rotor. I’d ask Cobalt if they could make a 17 mm thick AP2 pad.

The larger pad has a lower contact pressure (same force the caliper generates) so you should see slightly better rotor wear.

380/2-43/2=168.5
380/2-49/2=165.5
% diff = (168.5-165.5)/165.5x100=1.813%

So the %diff of the mean rotor is ~2% so approximately 2% reduction in torque per each side of the caliper for the same caliper piston area per side. So a total loss of ~4%. Do you have the piston diameters? If you do then I can calculate the static brake bias.

[ZM2]

Originally Posted by M3SQRD

I can’t comment on the 9660 caliper but the 9668 with a 25 mm fits tightly on a 34 mm thick rotor. Perhaps the 9660 has extra pad clearance on a 30 mm thick rotor. However, the Cobalt 20 mm thick pad may cause a problem with a 34 mm thick rotor. I’d ask Cobalt if they could make a 17 mm thick AP2 pad.

The larger pad has a lower contact pressure (same force the caliper generates) so you should see slightly better rotor wear.

380/2-43/2=168.5
380/2-49/2=165.5
% diff = (168.5-165.5)/165.5x100=1.813%

So the %diff of the mean rotor is ~2% so approximately 2% reduction in torque per each side of the caliper for the same caliper piston area per side. So a total loss of ~4%. Do you have the piston diameters? If you do then I can calculate the static brake bias.

Got it on the 9660 and pad thickness. So we’re saying XR5’s are a no go?

Rear Paragon PA025 caliper pistons are 27/27. Sounds like I might start running 7766 vs 7767 in the rear anyways.

Appreciate it!

[M3SQRD]

Originally Posted by ZM2

Got it on the 9660 and pad thickness. So we’re saying XR5’s are a no go?

Rear Paragon PA025 caliper pistons are 27/27. Sounds like I might start running 7766 vs 7767 in the rear anyways.

Appreciate it!

I would ask Cobalt if they’d make a 17 or 18 mm thick version. They make one-off custom pads so it should be simple to make a thinner existing pad.

At least you have more compound options between the two pad profiles compared to the 7768. A lot of people don’t know the 7768 can be easily made by enlarging the inner radius of a 7767 pad. It seems the Radicals use the larger PFC 7767 pad and the identical pad offered by other brake manufacturers.

So you have the AP Racing 9660 front caliper with a 378 mm OD rotor and PA025 rear with a 380 mm OD rotor, correct? I’ll calculate the brake bias tomorrow or Friday.

[ZM2]

Originally Posted by M3SQRD

I would ask Cobalt if they’d make a 17 or 18 mm thick version. They make one-off custom pads so it should be simple to make a thinner existing pad.

At least you have more compound options between the two pad profiles compared to the 7768. A lot of people don’t know the 7768 can be easily made by enlarging the inner radius.

So you have the AP Racing 9660 front caliper with a 378 mm OD rotor and PA025 rear with a 380 mm OD rotor, correct? I’ll calculate the brake bias tomorrow or Friday.

Yes, Sir. Appreciate it. Happy Holidays!

[jritt@essex]

Yes, our advice is that if you're in North America, run away from non-Essex 'AP Racing brake kits'. We have people call us all the time who have gone down this path, and can be a real nightmare. Last year I was a guest on a YouTuber's channel who was dealing with this topic (below), and I explain what can happen if you do go down this path, and why we do things the way that we do. This particular gent bought a brake kit that he thought we produced...then found out it didn't fit, he couldn't buy correct parts, was basically out $4,000, etc., etc. No fun!

[Chris N]

Great PSA video!!

I bought a used Essex kit from a Bimmerpost classified. I had no idea that fake kits were a problem until I called Essex to schedule a rebuild/Recertification. My heart sank, I almost puked when they asked if I was sure it was an authentic Essex brake kit. Fortunately, mine was indeed the real deal. However, I'm not sure that the shock of possibility loosing $5k was worth the money i may have saved. Like the video states, "buy once, cry once."

[Maynard]

If all you lose is $5k, you will have gotten off easy (i.e. easier than having brakes fail on track/road).

[HP Autosport]

We have seen an AP BBK sold by a shop in the Bay Area that looks to be AP 9660 calipers, but something was off on it. Either the rotor rings or the hat was wrong(not floating or wasn't J-hook). It could have been a knocked-off 9660 calipers, but we didn't get a chance to verify.

[M3SQRD]

If anyone is looking for an authentic lightly used (~4k miles) Essex/AP Racing CP9668/CP9449 with 372/365 mm OD j-hook rotor front & rear brake kits (purchased from HPA/Harold) send me a PM. Medical issues forced me to sell what was supposed to be my f82 forever car in individual Moonstone Metallic exterior/Opal White interior.

[bipp]

Originally Posted by M3SQRD

If anyone is looking for an authentic lightly used (~4k miles) Essex/AP Racing CP9668/CP9449 with 372/355 mm OD j-hook rotor front & rear brake kits (purchased from HPA/Harold) send me a PM. Medical issues forced me to sell what was supposed to be my f82 forever car in individual Moonstone Metallic exterior/Opal White interior.

If it wasn't apparent already by his posts, M3SQRD is a class act and I'd have no hesitation buying from him - obviously a guy that takes good care of his stuff.

[M3SQRD]

Originally Posted by bipp

If it wasn't apparent already by his posts, M3SQRD is a class act and I'd have no hesitation buying from him - obviously a guy that takes good care of his stuff.

Thanks!

[NathObeaN]

Originally Posted by VGSON

yeah im passing on this “kit”.

so..which brake pads are yall running for daily’s? looking for better stopping power and less dust..

wgmotorwerks are a reputable shop/garage in the UK. You’re on a forum dominated by US individuals who all buy from Essex and often don’t understand that AP racing is a UK company who don’t sell ‘kits’, they sell parts. It’s up to their resellers (Essex being the largest in US) to put kits together. In the UK, different resellers put different kits together at different prices, some with j-hooks, some with curved groves etc.

You can usually contact these resellers asking for your preferred disc, pad, lines etc.

[M3SQRD]

Originally Posted by NathObeaN

wgmotorwerks are a reputable shop/garage in the UK. You’re on a forum dominated by US individuals who all buy from Essex and often don’t understand that AP racing is a UK company who don’t sell ‘kits’, they sell parts. It’s up to their resellers (Essex being the largest in US) to put kits together. In the UK, different resellers put different kits together at different prices, some with j-hooks, some with curved groves etc.

You can usually contact these resellers asking for your preferred disc, pad, lines etc.

I think we “US individuals” know AP Racing is a UK company owned by an Italian company. If it was a properly assembled UK kit then they’d know the CP9660/CP9668 caliper can use a max rotor OD of 380 mm. 390 mm OD is too large for the CP9660/CP9668. Also, 355 and 362 mm OD rotors are not ideal options for the f8x and would require massive brake cooling. Pad and rotor wear, especially the CP9660 18 mm thick pad, would be excessive. No information about the rotors, besides their ODs, are listed in this kit, such as, rotor thickness, vane count and brand. The AP Racing floating rotor design is not used. I can’t tell if a floating rotor or floating hat design is being used. Can the rotors only be sourced through them? It doesn’t even state whether the stock drum parking brake is retained (I doubt it does on the 355 and 362 mm OD rotors because their hat diameter is too small). Yes, there are properly assembled AP Racing brake kits in the UK but I would not put this kit(s) in that group.