1988 power brake problem
Thread Starter
Heel & Toe
Joined: Jun 2010
Posts: 16
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1988 power brake problem
I have a 1988 rag top with 22,000 original miles. I bought the car with 18,000 miles and obviously only drive it occasionally. As long as I've owned it the power brakes seem to need more pedal pressure than it should. It feels like it has standard non assist brakes. It does not pull to either side during braking. I have checked the booster and check valve. Both are operating properly. The vacuum applied to the booster is as it should be. There are no leaks or anything else out of the ordinary, it just takes more pressure applied to the pedal than power brakes should require. Any help would be appreciated.
Burning Brakes
Joined: Nov 2011
Posts: 841
Likes: 1
I have a 1988 rag top with 22,000 original miles. I bought the car with 18,000 miles and obviously only drive it occasionally. As long as I've owned it the power brakes seem to need more pedal pressure than it should. It feels like it has standard non assist brakes. It does not pull to either side during braking. I have checked the booster and check valve. Both are operating properly. The vacuum applied to the booster is as it should be. There are no leaks or anything else out of the ordinary, it just takes more pressure applied to the pedal than power brakes should require. Any help would be appreciated.
Last edited by caddyboy84; Apr 1, 2012 at 10:37 AM.
Burning Brakes
Joined: Nov 2011
Posts: 841
Likes: 1
Check your manifold vacumm and then the booster itself. It could only be the booster or a fualty master. Bleed all four corners and check the calipers. I just remembered the ABS pump and the porportioning valve, might want to look into those things as well.
Last edited by caddyboy84; Apr 1, 2012 at 04:03 PM.
Burning Brakes
Joined: Nov 2011
Posts: 841
Likes: 1
If you're sure everything is good, the only thing thats left is the ABS pump under the driver-side rear speaker. I'm gonna do a little research and find out about the symptoms of a bad one. Do the brakes feel the same if you disconnect the booster vacumm? This is kind of strange for a car with such low miles, the brake system is pretty straight forward. You have bled all for corners right? My manual says that it may be a good idea to chech the ABS unit and it's electrical connections, also the ABS fuse in the fuse box.
Thread Starter
Heel & Toe
Joined: Jun 2010
Posts: 16
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Apparently you are on the right track. I found this thread and they talk about "Fred Flintstone brakes". That about sums it up. From what I've gleaned from all these posts, it is a common problem for C4's, and I need to figure out how to clear codes in the computer and then go out after a rain shower and force the car's ABS to engage 2 or 3 times. Now,.....do you know how to clear these codes?
Thanks
http://forums.corvetteforum.com/c4-t...n-finally.html
Thanks
http://forums.corvetteforum.com/c4-t...n-finally.html
Burning Brakes
Joined: Nov 2011
Posts: 841
Likes: 1
Apparently you are on the right track. I found this thread and they talk about "Fred Flintstone brakes". That about sums it up. From what I've gleaned from all these posts, it is a common problem for C4's, and I need to figure out how to clear codes in the computer and then go out after a rain shower and force the car's ABS to engage 2 or 3 times. Now,.....do you know how to clear these codes?
Thanks
http://forums.corvetteforum.com/c4-t...n-finally.html
Thanks
http://forums.corvetteforum.com/c4-t...n-finally.html
Last edited by caddyboy84; Apr 2, 2012 at 06:01 PM.
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Thread Starter
Heel & Toe
Joined: Jun 2010
Posts: 16
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Will just disconnecting the battery reset the codes? I just put a new battery in the car last week, so that in itself didn't do anything. I guess I'll wait for the next rain event to exercise the ABS. I'm in the Carolina's for the next 2 weeks. I'll get on it when I get back.
Burning Brakes
Joined: Nov 2011
Posts: 841
Likes: 1
Will just disconnecting the battery reset the codes? I just put a new battery in the car last week, so that in itself didn't do anything. I guess I'll wait for the next rain event to exercise the ABS. I'm in the Carolina's for the next 2 weeks. I'll get on it when I get back.
Thread Starter
Heel & Toe
Joined: Jun 2010
Posts: 16
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The booster was the first thing that came to mind for me as well, but it is good. Did you check out that thread? My car acts just like the ones they talk about. Apparently the ABS can screw up over a period of time and can be "realigned" by forcing it to activate on wet streets. It makes sense since so many other owners were having the same problem at the time of that post.
Burning Brakes
Joined: Nov 2011
Posts: 841
Likes: 1
The booster was the first thing that came to mind for me as well, but it is good. Did you check out that thread? My car acts just like the ones they talk about. Apparently the ABS can screw up over a period of time and can be "realigned" by forcing it to activate on wet streets. It makes sense since so many other owners were having the same problem at the time of that post.
I just thought of something, don't kill yourself with that brake test, I've never heard of that but I'm gonna ask around.
Last edited by caddyboy84; Apr 2, 2012 at 09:34 PM.
Burning Brakes
Joined: Nov 2011
Posts: 841
Likes: 1
Sometimes ya gotta have a little patience and do some more research or reading, a lot of times I used what I learned here and kinda expanded on it by doing more research. I would hate to have someone do anything they didn't have to, so you might want to get more info before gutting out the back of the car. I've always found the guys at the dealership to be helpful in trouble shooting things for me.
Last edited by caddyboy84; Apr 3, 2012 at 12:01 AM.
Team Owner
Joined: Dec 2000
Posts: 90,675
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From: SE NY
Cruise-In II Veteran
If you pull power to reset the ECM codes you lose radio & clock presets.
I prefer to open the connector in the thin Orn wire comming from the battery + terminal as that only removes power to the ECM.
I prefer to open the connector in the thin Orn wire comming from the battery + terminal as that only removes power to the ECM.
Burning Brakes
Joined: Nov 2011
Posts: 841
Likes: 1
Thats true. I hate having to re-set all that crap. Thats why resetting through a scanner is so much better.
Thread Starter
Heel & Toe
Joined: Jun 2010
Posts: 16
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Guess it's a mute point at this stage since I just replaced the battery anyway. So I've got the codes cleared, now I just need to cycle the ABS. Sounds like it's a bit of a pain to get to the ABS if I don't have to. I may just do the wet street thing first and see what happens. I have a 68 tri-power with 2 pedals. The one on the right bangs your head on the back glass, and the other bangs your nose on the dash. The 88 is my wife's car and the go pedal is no slouch for what it is, but that whoa pedal sucks and always has since I've had it. I'll get it figured out eventually. As many folks that chimmened in on that other post, I'm surprised this one hasn't generated any more response from others that have had this problem. Anyone else resolved this issue?
Heel & Toe
Joined: Oct 2009
Posts: 22
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From: Kingsport TN
I have the same problem. Put new brake shoes and turned the rotors. You can stand on the brake pedal and the car just slows. The anti lock light came on but now has gone off. I still have bad brakes. Mechanic first words. We're booster. Sounds like that's not the problem. Mechanics here just like changing parts.
Racer
Joined: Feb 2012
Posts: 442
Likes: 3
From: Hendersonville TN
Same thing on my 89. Brakes require a lot of pressure to stop quick and feel a bit manual like. I am going to bleed the system in case there is air and add Hawk HPS pads. I've read that they really increased stopping performance for people like us with this problem.
