New Front rotors won't sit flush on hubs

I can't get my new PowerStop rotors to fit the front of my 2004 Cabriolet. All the dimensions match up with the existiing rotors, but there remains a 1/16" gap between the hub and the inner face of the rotor. Disturbingly, the rotors have stickers that say 'Rear Driver's side' and 'Rear Passenger Side', but they are definitely not rear rotors. I only tried the driver's side,Rotor assuming the same would happen if I tried the other one. I used a deadblow hammer to try to nudge the rotor flush, but no luck. Temporarily admitting defeat, I put the old rotor back on with no problems and tightened the phillips screws and went on with my life. I'm planning to put some FEAL coilovers on in a few weeks, and that would be a good time to install new rotors. So, here's my question (s). Did I miss something? Has anyone else had a problem installing PowerStop EBR834 XPR rotors? I called the manufacturer and the customer service rep had not heard of similar complaints (although she did apologize for the mislabeling error). I've done lots of brake jobs on similar vehicles and never had this problem. None of the threads or YouTube videos on Porsche brakes gave me a clue as to what I might have done wrong. Thanks in advance for not replying, "Just take it to the dealer and give them $2,000. They'll know what to do!" Here's a pic for attention. You can see the gap where the rotors don't sit fluch by looking at the bolt holes.

I'm not sure I am understanding this, but could they be warped? Have you got access to a flat plate where you can see if the outside face lies flat?

Sounds like you've got either the wrong discs or discs are defective. Something isn't machined correctly to allow fit over the inner hub. If there is nothing sticking out from the hub or inside of rotor, the correct fit rotor should fit right on as you know. I'd try the other side rotor just to see if it fits. Then maybe try them on the rear to see if the mislabeled rotors really were not mislabeled...

Being new rotors there should be " marks " on the inside from you trying to push/force them on . Take a picture or two of the marks and share with the vendor . It does appear that you received the wrong rotors .

Thanks to all for the responses and suggestions! I'll try to respond as best I can. As you can imagine, it's a pain to take off the wheel and caliper to try putting the passenger side rotor on to see if it will fit flush on the driver's side, but I took pictures and measurements of the two rotors, and to the best of my ability I am seeing that they are both machined identically in the area that is giving me problems- the rotor 'hat'. There is a lip close to the mating surface on both rotors, and that might be a problem. Warpage? Nope. I placed the two new rotors on top of each other and there are no wobbles, so they're both flat, as you would expect with new rotors. My rear rotors are stock (as are the fronts) , and smaller diameter than the fronts, so I don't think trying the new rotors on the back would be productive- even if they fit the hub, the calipers would not clear them (and that would be a lot of work, too! ). My hope was that someone would respond, "The same thing happened to me, and here's what I did..." So....my likely next step is to buy new rotors from a different manufacturer and move forward. Here are some pics of the insides of the rotors with the lip that I suspect is preventing them from seating properly, but both rotors look identical in that respect. Again, Thanks to all for applying your problem solving skills. I appreciate the validation that I'm not crazy!

Someone turned off the CNC machine before it finished the job and the guys in QC were out that day.

Rotors sometimes do have QC problem. I have received Zimmermann (OEM quality) rotors in the past for a different car that was severely warped/out of balance right out of the box.

A few times I purchased some super cheap brake rotors from BrakePerformance.com or something like that. They had some QC issues and despite opting for their performance rotor they did not hold up to being used at the track. I wouldn't recommend that brand, but my experience was from several years ago. Sorry, I only have this anecdotal contribution.

Looks like they are rear rotors to me. That inner ring is for the parking brake shoes.

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I was gonna say the same thing. Those r rear rotors. The front rotors dont have a machined perpandicular surface. Edit...looked up some pics and its hard to tell as some manufactures make them different but it really looks like u have the wrong rotors. They look like the rear gt3 (or 6-turbo i think) rotor.

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You might think that, but that's just the way the rotors look on the front. They do have a deep 'hat' that resembles a parking brake drum. Believe me, I wanted to believe they were rear rotors because of the label on them, but the rears really are smaller diameter and these wouldn't fit on my 996 at the back. When I called the manufacturer, they asked me to read the part number etched on the edge of the rotor. That confirmed they were the correct part, i.e. front rotors for 996. I tend to agree with others who say that it's just a QC issue- dimensionally, these rotors look 99% like the ones I planned to replace. Those rotors were not yet down to minimum thickness, but while I was rebuilding the calipers, I thought, "Why not?" Oh, Well! Here's a picture of the existing front rotor with its wide hat. From the back side, it looks even deeper, like a parking brake drum. (Please ignore the claw hammer. Only official Porsche tools were used in performing this brake job!)

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They look like that to me as well, despite what the mfgr said. Just a thought as the 6Turbo rear rotors are the same diameter as the Carerra front rotors.

C4S rear rotors are the same for C2 front (standard brakes / black calliper.) in terms of thickness/ 318mm etc... So cast one 'rotor' to rule them all? I dunno

justinbAUS, the only way to tell is to put them in a fire or get enough heat that they glow.

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I went to FCP Eiuro's Brake Guide site and couldn't verify any use of 318mm rotors on any 996s except fronts. https://www.fcpeuro.com/blog/the-def...che-996-brakes I went to the RockAuto site, where I bought them, and they don't even show PowerStop rotors for those models, so I don't think that these are rear rotors for another model. As the PS customer service rep said when I read the stamping on the edge of the disk said, "That's the right part number for the 996 fronts." Again, Thanks to everyone for your thoughts and prayers ( ), but I'm siding with those who say these were spec'd for my car, and produced on a Friday afternoon, after the QC guy went home. The good news is that the original rotors went back on and they have 'some' life left in them. (They measure 27mm on my plastic Harbor Freight caliper, and 26 is the minimum.)

If you had the lip machined off would they fit correctly?

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I'm guessing the answer to that would be yes, but not with 100% certainty. If I had a caliper that could accurately measure that distance, (and if i took the old rotor off), I might be able to determine via comparing both rotors just where the problem lies. As it is, My car is doing well with the old rotors. When I get my coilovers, I might revisit the problem. I'm curious what might be involved in getting that lip machined down.

It could be mounted on the hub. Put the caliper on. Measure the distance from each side to the caliper, then subtract the height of the ridge and see if its centered prperly on the caliper. Given a lathe with a tall enough center, and its chucked up square, it should be easy to remove the extra material.

Did you set one new rotor next to an old rotor side by side ? Did the old rotor have that " lip " ? Did you take pics side by side ? That should be enough evidence for Rock Auto to issue a return/refund AND hopefully they would cull their inventory of that part number for inspection .

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I had the same thought. Also, can you measure the ID of the hat on both old and new? That may help confirm the lip is the only difference.

Why not just consider it a loss and get some correct rotors from FCPeuro, Rennline, Suncoast, or another Porsche focused site? To be clear, I do not mean this to sound snotty or rude. Also, I am in NW DC and I have a set of brand new Sebring front rotors you can use to compare if you’d like? Olney is relatively close.

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Agreed. I'll probably get new rotors from one of the Porsche aftermarket vendors. The ones I've got now are within spec, so I'm not in a rush. I could have returned them to rockAuto, except for a glitch in their website: I started the return when I saw the "rear" stickers on the disks, then after going through a couple of steps decided to close the window and actually try fitting them on. After confirming they didn't fit, I went back to restart the return process. When I brought up my order it showed the rotors as nonreturnable giving the reason "not eligible for return, since parts were installed/used." (or words to that effect). WTF??? Rockauto does not accept phone calls, and there is no way to reach them to say, "WTF, guys, It was OK to return the parts an hour ago, and now it isn't?" So I opened a dispute with my credit card company, and they resolved it in my favor. If Rockauto wanted them back, I'd have no problem sending them back. The pictures show there's nothing 'used' about them. Oh, well! (Thanks for the offer to compare the disks side by side. I'm not sure what could come out of it, but It's always good to meet another Porschephile!)

I ordered a pair of rotors a couple years ago. One side did not fully seat like yours. I switched sides to check fitment and the one that didn't seat fully did not seat fully on the other side as well. I returned them and it was replaced with a new one. The new one fit fine.