SKF engineer

I searched using a number of different word combo's and I found some interesting things but none that seem to match my issue. My car is a 2001 coupe with the MN6 transmission, mostly stock... Today on my drive to work, (25 miles of mostly back roads) I noticed the car didn't seem to roll right at spot signs, like something was dragging. I get to work and I test roll a few times in the parking lot and again it's like someone is very lightly applying the brake. Fast forward to the end of the day, I figure the problem will still be there so I test again leaving the office and the problem is gone... No braking drag. I get about halfway home and it starts again. I do a rolling test again once home and it's the same thing, the car rolls but feels like it's not 100% free and then stops. I jacked all four wheels off the ground and find that only the front two wheels are dragging, it's not much but enough that when I turn it by hand I need a little more force. Again this only happens in the front the rear has no drag. Once the car cools the issue goes away again.

In the searches I found it seems like if it's the brake booster all four wheels would drag, and if it was an ABS or proportioning valve issue then it wouldn't get better when the car is cold. Also in case it matters I just had to replace the stop light switch and during that job I pressed very hard on the brake pedal a couple of times when the car was off, not sure if that makes a difference for some reason.

Anyone have any idea why only the front brakes drag after a long run. (over 30 mins)

Thanks

Corvette_Ed

My guess would be the calipers or the rotors.

1986coupe

Take the callipers off and lubricate the pins with brake lubricant. That should help. Do the back at the same time, just so you know it has been done. If it doesn't then you may need new callipers and brackets.

SKF engineer

My first thought was to pull the calipers and lube the pins also, I just found it odd that both of the front wheels had the same drag when I jacked it up and turned the wheels by hand. Hopefully I'll get a chance to jack it up and lube everything this weekend.

DeeGee

I posted this How To when I replaced my brakes and rotors. There are a few pictures in there that wil help you when you try the lubrication. It should be obvious if the pads are binding on the rotors as you'll get abnormal wear.

http://forums.corvetteforum.com/c5-g...nd-rotors.html

Supercharged111

Do your rotors have a deep wear groove in them? The edges of the pad can grab that groove and give the feeling you describe. Since it doesn't happen until you drive a bit though, it makes me think the caliper pistons are sticking. Both fronts do it or just one? If both, caliper sticking seems a bit less likely. Has it ever pulled to one side? Trying to determine if both fronts acted up at the same time or if one went then the other.

LoneStarFRC

Is the wheel in question getting hot? Check them after driving and this situation comes up and see if it/they are hotter than normal. That can indicate a dragging pad as well and narrow down the search for which wheel is being affected.

Check your brake hoses as well. If the inside is damaged (ply-separation), swollen, coming apart, etc it can act as a checkvalve and the sypmtoms may show up after driving and several stops. Fluid can't return quickly and maintains too much pressure and bleeds off back to normal slowly after sitting/cooling down.

HTH

CHJ In Virginia

Two possible causes are 1) sticking caliper piston. It's not retracting when foot is off the pedal. Rebuild or replace caliper. 2) Flexible rubber brake hose delaminating internally. Fluid flows one way but is blocked from returning causing piston and brake to stay applied. Replace hose - do all of them if this is the problem.

SKF engineer

Since it was raining today I had a chance to go pull the wheels and go over the brakes. All of the calipers are floating as designed. I removed and relubed all of the pins since I was there but none of them had dried up or become stiff. I also checked the pad wear, both pads on all the brakes are even. The rotors also have very little wear or groves, the pads and rotors were replaced about 5000 miles ago.

The first thing I thought of when I thought I had an issue was going around to check the heat of the brakes when I got to work. While the fronts were warmer I could still touch them for a short period of time. Also again when I got home I jacked up the whole car and the fronts were dragging the rears were not. Once the car sat for an hour the issue was gone but if you drive it for over 30 mins it comes back. There was some TSB about the booster going bad and creating a drag but I would assume this happens on all four wheels not just the front.

Oh and I agree with the brake hose issue I had that on my camaro before but I found that even with bad hoses the brakes release after a minute or so, these need to sit an hour before they don't drag and the issue doesn't come back for 20-30 minutes once your driving. I would assume the brake hoses would show themselves rigth away. Oh and btw, the car is braking straight and true...

Still stumped...

Supercharged111

This happened to me in my Trueno (2 door Corolla coupe) in Japan when I swapped a boat anchor out for a less slow supercharged engine. As soon as I did this, the brakes quit releasing and by the time I got to work the car would barely move. Sometimes I'd have to crack the bleeders just to get the car to move, it was ridiculous. I unplugged the booster and the problem stopped, so I replaced the booster. Why not try unplugging your booster and going for a drive when there's not much traffic? Easy way to verify if that's what it is. Remember, your back brakes could be contributing but since they're biased to participate less, they might not be noticeable.

SKF engineer

I that is going to be my next test, it will have to wait a while since I need to take it on a longer drive but for sure I'll have tried that by this weekend.

I'm a little upset at myself if it's the booster, I had no idea there was a TSB related to weak springs in the boosters and I pushed on it pretty hard while I was replacing the stop light switch two weeks ago. I feel like it's one step forward and two back this year.

Stay tuned I'll report back

buddyfew

i had this problem after replacing new rotors, clips that hold brake pads was the source of trouble.

2kbluestreak

To check on 1. when you feel the brakes are dragging, find a safe place to pull off the road at a paved level spot and stop the car. Push real hard on the brake pedal. Release the brakes and start it rolling a little, then put the shifter into neutral. If the car rolls freely, you likely had stuck caliper pistons, probably from dried fluid.

Former SKF Engineer.

k24556

don't forget about the emergency brake. You could be dragging it.

SKF engineer

It was about 7 weeks ago I first noticed the brake issue and started asking about solutions on this forum. Based on some of the reply's I suspected the brake booster, grabbed some pliers and something to plug the vacuum line so I could try disconnecting the booster and test drive when the issue occurred again.

At that time, while in my garage and the vette was cold, I also removed the vacuum line from the brake booster just to make sure it wasn't stuck. When I removed the line I heard a slight hiss for a second which I dismissed. I then proceeded to drive the vette as I normally would (about once or twice a week averaging about 70 miles a week) waiting for the issue to occur. It didn't occur, I was perplexed but for a lack of a better answer I started to assume the hiss I heard was some sort of pressure that had built up and couldn't be released in the booster and by removing the line I had addressed the issue for the time being.

That was until today I hadn't driven the vette for about 12 days due to the "super storm" we had on the east coast but the weather was nice and I figured it was patriotic to drive the vette on election day. On my way to work, about 23 miles in and 30 minutes, I noticed the brakes started to drag again. I pulled over as I planned 7 weeks ago, removed the vacuum line from the booster and plugged the line. I then proceeded to get in the car and drive. Three things I learned, one the brake drag did not go away, two it still felt like I had power brakes and three something I didn't note in the past the brake pedal feels more firm when the issue occurs. I'm still wondering about the booster but I'm also open to any thoughts based on the newer information.

To those that have made suggestions in the past, Thanks. Please keep in mind I have jacked the vette up during the issue and found it is the front brakes that appear to be dragging and they appear to drag equally. The rears may also slightly have the dragging issue but I didn't notice when I turned them by hand. The vette does not pull to one side during braking and the issue seems to occur only on trips over 20 minutes. Also I have not serviced the brake system or replaced the pads and rotors in the last year or more so it is unlikely this is the result of improper brake service or component installation. The brake fluid was flushed ~5000 miles and 5 years ago.

The Mountain Kat

How old are the brake hoses? A deteriorated inner lining can act as a one way valve. This will hold pressure on the calipers/pads.
When I bought my car I was halfway home when the brakes started something similar. I noticed that the brake pedal was not engaging the master cylinder until halfway down. It turned out that the return spring in the master cylinder had broken. A quick dis-assembly of the MC and a trip to the local Ace Hardware had the problem fixed for $3.30. Thirty cents of which was taxes.

Tron Z

[QUOTE= ... Also in case it matters I just had to replace the stop light switch and during that job I pressed very hard on the brake pedal a couple of times when the car was off, not sure if that makes a difference for some reason. ... [/QUOTE]

It is not clear to me whether the dragging symptom occurred before, or after the stop light switch was replaced. If after, I don't recall seeing any mention that the OP went back and QC'd his stop light switch install, to verify that the brake pedal was releasing completely. I would suggest that the OP verify that the pedal is returning completely if that has not yet been done.

byronhunter

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Been watching this since it was first posted, wondering since day one if someone would bring this up. Sure wouldn't hurt to check it. Good Luck
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From the SM.
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Stop Lamp Switch Adjustment
With the brake pedal depressed, insert the stoplamp/cruise control switch into the retainer until the switch body seats in the retainer.
Note that CLICKS can be heard as the threaded portion of the switch is pushed through the retainer.
Slowly pull the brake pedal fully rearward against the stop until the CLICK sound can no longer be heard. The switch will be moved in the retainer providing proper adjustment.

SKF engineer

Thanks for the idea, I have not checked to see if the stop light switch is keeping the pedal from fully returning. It was the end of the summer and very hot when I replaced it so I just snapped everything back together, confirmed the brake light worked and went on my way.

When I visually check it should be fairly easy to confirm the pedal has returned but I'm unsure about listening for the "clicks" of the switch.

If this is the cause then it further strengthens the saying "Keep It Simple Stupid". It's also why I wrote half a novel about the events around the issue as I believed there might be a piece of the puzzle hiding in what some might dismiss as not important.

I'll check under the footwell in the next few days and write back.

SKF engineer

In the interest of completing the loop on this thread I wanted to fill everyone in on the final answer to my brake dragging question. I need to thank TronZ for first giving me the idea to check the position of the brake light switch and others for all of their help. The problem was related to the brake light switch postion, I had installed the switch so that it was the farthest it could be toward the firewall. A few weeks ago I climbed back under the dash to investigate and I realized the brake pedal was resting on the switch body. It took over 1/2" of adjustment before the brake pedal was no longer resting on the body of the switch. I'm glad this was the answer as I really wasn't looking forward to the idea of replacing the master cylinder or something of that nature. Thanks again.

George