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Discussion Starter #1
Gently driven 2017 street Evora 400. I have brake pulsation - both steering wheel wobble and brake pedal chatter while braking. I first noticed symptom around 3k miles, now at 5k and situation is getting worse. It's too few miles for 2 piece rotors to be warped especially on a street car.

Anyone have this experience? Other than making sure pads aren't glazed, and measuring runout on rotors and hubs, is there anything else to be checked?
 

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Your rotors are NOT warped. You have substrate buildup because it is TOO gently driven. Take it up to 100+ and stand on them a few times. Problem solved.
Even my 11S POS as you say doesn't have those problems. User error. If you look at the rotors and see marks were the pads have adhered to the rotors from car washing etc
 
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Hey xxaarraa,
I'd also recommend that you cycle them hard half a dozen times. Very likely will make them better.
 

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However, if you hard cycle them as described above and they don't improve in vibration, they are likely warped. My car is at the dealership right now, and the fronts and rears are warped. Gentle (for the most part) street driving. Definitely no track time. There is another thread that I discussed my experience with this car so far.
 

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Discussion Starter #6
However, if you hard cycle them as described above and they don't improve in vibration, they are likely warped. My car is at the dealership right now, and the fronts and rears are warped. Gentle (for the most part) street driving. Definitely no track time. There is another thread that I discussed my experience with this car so far.
Just saw your post on this topic. Did you ever figure out why your replacement ultradiscs also warped early? Did you measure runout on your the hubs?
 

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Take the front wheels off and mount a dial indicator, it's very easy to check.
This setup was for a different reason, but you get the idea.
1268410
 

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I still haven't figured it out. The dealership did measure hub runout (I'm not completely clear what that is) last time, but they indicated it was within spec. I'm now wondering if the prior owner (who only put 989 miles on it before I bought it) crashed it and now the geometry is off? I did have a detail shop tell me they found some weird specks of residue on the paint, as if it had been in an autobody shop before. Dealership doesn't think this is the case given the condition of the underbody of the car though (no evidence of impact anywhere, aluminum undertray completely flat/smooth). Dealership thinks the two-piece rotors used on earlier models had some "bad batches." However, I'm now supposedly on the "better" batch of factory rotors. Still warped, and it's a mystery. Fingers crossed Lotus will honor their prior work while it was under warranty and replace the current ones. Out of warranty now. :(
 

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I still haven't figured it out. The dealership did measure hub runout (I'm not completely clear what that is) last time, but they indicated it was within spec. I'm now wondering if the prior owner (who only put 989 miles on it before I bought it) crashed it and now the geometry is off? I did have a detail shop tell me they found some weird specks of residue on the paint, as if it had been in an autobody shop before. Dealership doesn't think this is the case given the condition of the underbody of the car though (no evidence of impact anywhere, aluminum undertray completely flat/smooth). Dealership thinks the two-piece rotors used on earlier models had some "bad batches." However, I'm now supposedly on the "better" batch of factory rotors. Still warped, and it's a mystery. Fingers crossed Lotus will honor their prior work while it was under warranty and replace the current ones. Out of warranty now. :(
The reason why hard braking helps is because you get a microscopic, uneven layer of deposits on the rotor that cause the pad to grab differently as the wheel rotates. If the brake pedal vibrates but the rotor runout is in spec, this IS what's going on. You basically need to bed the brakes in. When the guys above say hard braking, they mean to get the rotors dang near glowing. If your passenger doesn't freak, you didn't do it hard enough. Then repeat ten times without ever coming to a complete stop. In my daily, the pedal went to the floor after the 5th, so it's pretty fun :)
 

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I still haven't figured it out. The dealership did measure hub runout (I'm not completely clear what that is) last time, but they indicated it was within spec. I'm now wondering if the prior owner (who only put 989 miles on it before I bought it) crashed it and now the geometry is off? I did have a detail shop tell me they found some weird specks of residue on the paint, as if it had been in an autobody shop before. Dealership doesn't think this is the case given the condition of the underbody of the car though (no evidence of impact anywhere, aluminum undertray completely flat/smooth). Dealership thinks the two-piece rotors used on earlier models had some "bad batches." However, I'm now supposedly on the "better" batch of factory rotors. Still warped, and it's a mystery. Fingers crossed Lotus will honor their prior work while it was under warranty and replace the current ones. Out of warranty now. :(
Doesn't sound good with weird specks of paint. Some have been known to hide accidents so it does not appear on Carfax.
 

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Gently driven 2017 street Evora 400. I have brake pulsation - both steering wheel wobble and brake pedal chatter while braking. I first noticed symptom around 3k miles, now at 5k and situation is getting worse. It's too few miles for 2 piece rotors to be warped especially on a street car.

Anyone have this experience? Other than making sure pads aren't glazed, and measuring runout on rotors and hubs, is there anything else to be checked?
It's very likely that the rotors are not warped unless they were running red hot. Dealers misdiagnose quite often and anecdotal references become facts in threads like this. In a previous life, I had issues very similar to this on my E39 because I chose a low dust pad. The bedding process described here helped a bit but eventually it all went away as soon as I switched to the stock pads. I would try changing the pads and bedding them in properly before I change rotors. Dave knows brakes.

 

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Take the front wheels off and mount a dial indicator, it's very easy to check.
This setup was for a different reason, but you get the idea. View attachment 1268410
I know you said this is for a different purpose. But I think the dial indicator needs to be mounted onto a rigid part of the suspension so any steering slack does not affect runout measurement.
 

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I know you said this is for a different purpose. But I think the dial indicator needs to be mounted onto a rigid part of the suspension so any steering slack does not affect runout measurement.
As I said it was for a different purpose, and as you can tell, it’s the rear wheel in the picture. It worked perfectly for me, your results may vary. 😁
 
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Discussion Starter #14
Oh, as far as aftermarket replacements go, the options I know of are:
  1. Inokinetic girodiscs
  2. GRP Alcons.
  3. EBC SG2FC2014?? EBC® SG2FC2014 - Fully-Floating Slotted 2-Piece Front Brake Rotors
I can't find costs for replacing just the rotor rings for either, so not sure which is better in long run. Any thoughts on girodiscs vs alcons?
Do folks have experience with GRP's Alcons? Inokinetic girodiscs seem to be a common choice. Curious what folks are replacing their factory rotors with.
 

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Do folks have experience with GRP's Alcons? Inokinetic girodiscs seem to be a common choice. Curious what folks are replacing their factory rotors with.
Have you tried doing what brgelise, others and myself would recommend you do?

If not, then it appears that you are just really wanting new rotors. If that’s the case, then this is an empty thread and frustrating for those trying to help you out.
You asked for opinions, and received good feedback on how to resolve your issue. It literally takes less than 10 minutes to bed the brakes.
 

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I've got 35k miles on my 400 with original rotors and I'm on my second set of pads. The car has 6 track days and 2 weekends at up at the dragon hitting all of those roads pretty hard. Dealer just serviced the car and said the rotors were still in spec. No idea why you would be so keen to replace the rotors with such low miles that are likely just fine. Seems like a waste.
 

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This is super common when you only light brake. The wifes cars always get it and I accept I have to do rotors every few years. If you leave it long enough it does damage the rotor though and you cant fix it by hard braking.

If you dont try the above recommendations first youre just wasting your money on new rotors. And if you dont thrash it like its supposed to itll just come back.
 

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Discussion Starter #18
Geez, touchy group. Yes I have tried hard stops as suggested and that has not resolved my issues. And yes, like I said right in my OP, I do intend to put the car up on the lift to check pads and measure runout of rotors and hubs before replacing anything.

Does it hurt to think ahead and gather information about rotors even if I am hoping to avoid having to replace them? I appreciate the feedback guys,
 

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Hey, here is a way that you clean your rotors:
Find an empty street, while in second gear, apply the brake about half force then the gas, you are using the force of the engine to heat your rotors, you will know its hot when they smell. You will drive about @ 25 mph - About 20 seconds of doing this 6 times will get the rotors really hot. Make sure that after you finish, nothing is on fire (brake pads can catch on fire when extremely hot) and DO NOT apply the hand brake, leave the car in gear.
 

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Hey, here is a way that you clean your rotors:
Find an empty street, while in second gear, apply the brake about half force then the gas, you are using the force of the engine to heat your rotors, you will know its hot when they smell. You will drive about @ 25 mph - About 20 seconds of doing this 6 times will get the rotors really hot. Make sure that after you finish, nothing is on fire (brake pads can catch on fire when extremely hot) and DO NOT apply the hand brake, leave the car in gear.
The above is called pad break-in, transferring pad material to the rotor surface to create the optimum friction surfaces.
If I could add some additional advice, after performing the above process, continue to drive for 10 minutes or so without braking if possible to allow your rotors, pads and calipers tp cool evenly. I learned this racing spec production cars with stock rotors and calipers. Otherwise where the hot rotor stops under the hot caliper after a race session tends to cook the pads and rotor surface further. I kept some RX7 rotors that heat checked under the pads as a reminder.... I doubt you'll have this issue, but rotors are expensive. It's called a "cool down lap".
 
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