[P2]

I'm feeling a shudder (pulsation) during deceleration under mild to moderate braking. On a braking scale from 1-10, maybe 2-4. I can feel it most when decelerating from ~50-40mph when the braking started above 60mph. I feel the shudder in my butt. Nothing in the steering wheel or brake peddle. The shudder is not pronounced and I had a bit of a time convincing the tech it was not the road. I've been playing with this to narrow it down for several months.

I thought for sure it was the front brakes as the dealer replaced the brakes under warranty in December and laser turned the rotors vs replacing them. Dealer says the rotors are fine.

Tech wrote:
"Performed visual inspection, no corrosion, blue spots, grooving or pad imprints found. Followed trouble tree attachment in SIB 34 01 14. No excessive play found in wheel bearing. Measured disc runout at .032mm, <.070mm. Measured wheel bearing flange runout at .007mm < .025mm. Measured thickness variation at .004 < .030mm.

I have my summers on. They are the factory setup.
225/40/18
245/35/18

I did hit a pot hole a few weeks ago. I cannot recall the severity before I hit it. Might be worse. But I thought maybe the issue was progressively getting worse. Not suddenly. I feel an ever so slight vibration at high speed. I may have bent a wheel slightly. Could that be causing the decel shudder?

Any ideas? I'm only have a few weeks remaining on the warranty and want to settle this before it expires.

[pikcachu]

Originally Posted by P2

I'm feeling a shudder (pulsation) during deceleration under mild to moderate braking. On a braking scale from 1-10, maybe 2-4. I can feel it most when decelerating from ~50-40mph when the braking started above 60mph. I feel the shudder in my butt. Nothing in the steering wheel or brake peddle. The shudder is not pronounced and I had a bit of a time convincing the tech it was not the road. I've been playing with this to narrow it down for several months.

I thought for sure it was the front brakes as the dealer replaced the brakes under warranty in December and laser turned the rotors vs replacing them. Dealer says the rotors are fine.

Tech wrote:
"Performed visual inspection, no corrosion, blue spots, grooving or pad imprints found. Followed trouble tree attachment in SIB 34 01 14. No excessive play found in wheel bearing. Measured disc runout at .032mm, <.070mm. Measured wheel bearing flange runout at .007mm < .025mm. Measured thickness variation at .004 < .030mm.

I have my summers on. They are the factory setup.
225/40/18
245/35/18

I did hit a pot hole a few weeks ago. I cannot recall the severity before I hit it. Might be worse. But I thought maybe the issue was progressively getting worse. Not suddenly. I feel an ever so slight vibration at high speed. I may have bent a wheel slightly. Could that be causing the decel shudder?

Any ideas? I'm only have a few weeks remaining on the warranty and want to settle this before it expires.

if the shudder is not on the steering wheel or the the pedal then it's the rear brakes...

if it was a bent wheel then it should also happen when you are not braking...

laser turned my butt.... turning rotors always lead to problems cause you are removing material.....in most cases the shudder returns and gets worse...

could be some rear wheel bearing

[P2]

Originally Posted by pikcachu

if the shudder is not on the steering wheel or the the pedal then it's the rear brakes...

if it was a bent wheel then it should also happen when you are not braking...

laser turned my butt.... turning rotors always lead to problems cause you are removing material.....in most cases the shudder returns and gets worse...

could be some rear wheel bearing

Thanks. I cannot find it written at the moment. But I think decelerating with the cruise control rocker primarily uses the rear brakes. So I just went for a drive and decelerated that way and the issue is significantly more pronounced. I have an apt Monday and will do that during a test drive with the mechanic.

I had some worry about the transfer case but am pretty sure I'd have other systems.

I agree about the rotor turning. The dealer does not do it if you pay. But when BMW pays, they said BMW insists if the rotors meet specs. Nonsense as far as I'm concerned. I don't even bother turning rotors on the family Honda's. It's just not worth the very small money saved.

[Maynard]

Exactly what I thought when they did that with mine at one of the warranty pad replacements - per the notes they turned it down .001, leaving .001 remaining within spec. I also had to ask, and they confirmed that they would not consider that a realistic option for a private repair. To their credit, they later replaced everything under warranty after obvious track abuse. And I did not notice any pulsing or issues with them (until I burned through the last of the factory pads coming into the bus stop).

One possibility might also be alignment related? Weird toe angles might give odd effects during braking. Also strikes me as a bit odd that you have that much thickness variation (.004) after just a few months. Those figures you cited are 30-50% of the way to the service limit, which I think should represent >30k miles of wear. I don't think that is up to spec for a fresh turning, but it has been a few decades since I miked rotors that carefully myself (me, I'd call Zeckhausen and ask what they think). This might be grounds to demand new rotors, and could suggest something is wearing them unevenly - usually misaligned rotors or sticking pistons. I'd make the request before warranty expires; doubt it will resolve quickly, but then you have a shot at it. At least have them re-turned and measured right then for a baseline, so if they really are wearing fast you know it.

[HP Autosport]

If you feel it at the seat of your pants, the problem is in the rear of the vehicle.

According to the TSB and spec, your runouts are both within tolerances. However, some wheel bearing runout or defect can only be detected under load.

[P2]

Originally Posted by HP Autosport

If you feel it at the seat of your pants, the problem is in the rear of the vehicle.

According to the TSB and spec, your runouts are both within tolerances. However, some wheel bearing runout or defect can only be detected under load.

I just got the car back. I thought the rear too. They ended up replacing the fronts properly this time with new rotors even though they insisted it was not the fronts two weeks ago. Problem solved now. I think I could not it feel in the steering wheel because of the electric steering.
Bad overall experience however. Two visits. When I brought the car in yesterday they acted like I did not have an appointment. It was in inconvenience to explain what was going on with the car. Kept it overnight no notice and seemed troubled that I would think I brake job could be wrapped up in a day. Now they want 10s on the survey. Probably just skip it. I don't look forward to paying for things when the warranty ends in a few weeks. But I do look forward to good service with the two Indys I use.

[HP Autosport]

Originally Posted by P2

I just got the car back. I thought the rear too. They ended up replacing the fronts properly this time with new rotors even though they insisted it was not the fronts two weeks ago. Problem solved now. I think I could not it feel in the steering wheel because of the electric steering.
Bad overall experience however. Two visits. When I brought the car in yesterday they acted like I did not have an appointment. It was in inconvenience to explain what was going on with the car. Kept it overnight no notice and seemed troubled that I would think I brake job could be wrapped up in a day. Now they want 10s on the survey. Probably just skip it. I don't look forward to paying for things when the warranty ends in a few weeks. But I do look forward to good service with the two Indys I use.

Glad you got it all sorted out.

Warped front rotors will typically be felt at the steering wheel and if it's bad enough you can feel it at the pedal too.