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Can't coast for crap

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Old Jun 24, 2007 | 01:37 AM
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Default Can't coast for crap

I think I may have a warped rotor on either of my front two wheels, but I'm not sure if that's related to my current problem:

Whenever I take my foot off the gas after driving at a steady speed, I can hardly coast at all. It almost feels like the brakes are VERY lightly being applied. The speedometer will instantly start going down as soon as I let off the gas; there's really no consistant coast going on at all.

This may or may not be related, but I've also noticed that around speeds of 50-60 mph, I hear what I can best describe as a "wobbling" noise. Imagine going over cobblestones that are hardly raised at all - very flat. It doesnt FEEL that way, but it sounds like it. No idea what this is or if it's related to my lack of ability to coast, but it's worth a shot to try and kill two birds with one stone.
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Old Jun 24, 2007 | 04:08 PM
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might have a bad caliper also, or several other things from axle bearings to like to you said rotors
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Old Jun 24, 2007 | 05:34 PM
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When you come to a nice easy stop, do you get a loping, lurching kind of stop? That is warped rotors. I have had 3 F-bodies, warp rotors on all. Real PITA. The next upgrade on this one is going to be brakes that don't warp, I hope.

But it does sound like you have a brake pad dragging. Does it pull to one side while you are coasting? That would point you to the problem side.
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Old Jun 24, 2007 | 06:29 PM
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Auto dont coast. The converter will slow you down, sometime even in neutral. Maybe tires underinflated? Dragging praking brake?
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Old Jun 25, 2007 | 01:02 AM
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I do get a lurching stop but I don't feel any pull one way or the other. The lurch was what initially pointed me in the direction of a warped rotor.

How can I remedy brake pad dragging - just getting new ones? It's about time to anyway.

Originally Posted by ghardester
When you come to a nice easy stop, do you get a loping, lurching kind of stop? That is warped rotors. I have had 3 F-bodies, warp rotors on all. Real PITA. The next upgrade on this one is going to be brakes that don't warp, I hope.

But it does sound like you have a brake pad dragging. Does it pull to one side while you are coasting? That would point you to the problem side.
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Old Jun 25, 2007 | 01:32 AM
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Sounds like it's time to upgrade to a C5 conversion... those rotors are like 12.8" I think.
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Old Jun 25, 2007 | 02:14 AM
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Originally Posted by Gallstaff
Whenever I take my foot off the gas after driving at a steady speed, I can hardly coast at all. It almost feels like the brakes are VERY lightly being applied. The speedometer will instantly start going down as soon as I let off the gas; there's really no consistant coast going on at all.
This definitely sounds like Deceleration Fuel Cutoff (DFCO). Once all of the DFCO enablers are met, it will almost completely cut fuel and retard timing which results in that braking effect your speaking of.
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Old Jun 25, 2007 | 03:03 AM
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Originally Posted by Shallow Bay
This definitely sounds like Deceleration Fuel Cutoff (DFCO). Once all of the DFCO enablers are met, it will almost completely cut fuel and retard timing which results in that braking effect your speaking of.
I've never heard of this before. Haha I've never even heard the term mentioned. But how can this be - I've never noticed this poor coasting ability with my previous two f-bodies.
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Old Jun 25, 2007 | 08:55 AM
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Also If its an A4 in D or 3rd the trans uses the Overrun clutch and gives a strong engine braking slowing the car down. In OD or 4th the car will coast a lot smoother.

Could all just be related to the brakes being warped though. I'd spend a bit more and replace all 4 rotors with Brembo blanks (no holes or slots) and whatever pads you wish. They are around $260 or so but well worth it. I warped 4 other brand rotors before I went to brembo blanks and have put 25K on them with no warping or anything.
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