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coreylubahn

Hard pedal, weak brakes - 95 Cutlass

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I recently bought my 95 Cutlass Convertible so I don't have a history with the car, but the car has, what I would call, terrible brakes. They stop me, and they will throw you forward in your seat a little if you two foot it, but I can't even get them to lock up, even on sand covered roads. I have said that if some animal was in the road, I would hit it because I wouldn't be able to stop fast enough. I have talked to the previous owner (who had the car for 17 years) and he said the car has always had a hard pedal with weak brakes. We have checked the calipers and they are all free. The car is supposed to have ABS but even under full brakes on a sandy road they don't kick in (probably because the tires never start sliding since they don't ever lock up). I did find a vacuum leak on the intake gasket so we will be fixing that to see if that helps, but I just want to make sure that I am not expecting something better than what I am ever going to get. What I have now just doesn't seem possible to be the way they came from the factory (but apparently is the way it has been for the last 17 years). Shouldn't I be able to actually lock the brakes up under a hard pedal?

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In my 1994 CS with the 3.4l, I am able to lock up the tires on pavement. I have put new brake hoses,calipers, rotors, and pads on my car. That was about 8 years ago now. The brakes are honestly not that great. I dont have a hard pedal, I always thought these cars had more of a softer pedal. You might have something wrong. As far as the ABS, I have only ever noticed mine kick on when on ice.

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I'm not sure if my 1991 is different but when I first got the car, I thought the same, thinking that "this cannot be right" ! After talking to the previous owner, he said religiously setting the parking brake was the solution. Explanation was that the rear caliper pistons would self-adjust only when the driver released the parking brake. Maybe that will help your case a little, though I know its only referring to the rear brakes.

 

Here is something I found on a forum related:

 

General Motors made a mistake in the design of the parking brake mechanism in the early W-Body cars with four-wheel discs (Lumina, Grand Prix, Cutlass Supreme, Regal). The rear caliper pistons would self-adjust only when the driver released the parking brake. But even drivers who routinely used their parking brakes would run into problems because of how it had to be released.

The fix is not just to repair/replace the worn parts in front, but also the rear calipers.

 

But repairing the parts won't prevent the problem from recurring unless the driver is educated about parking brake use.

 

In these cars, drivers don't only need to know they should use the parking brake, they also need to know that rear brake self-adjustment takes place only if the parking brake is released when their foot is OFF the brake pedal.

 

Unfortunately, we're all taught to release the parking brake with our foot on the brake pedal.

 

As a countermeasure, some technicians instruct owners of pre-1995 W-Bodies in a sort of "Saturday Morning Drill."

 

Drivers are told that once a week, with the car on level ground and the car in park or in 1st gear if not an automatic, to sit in the driver's seat and without touching the actual brake pedal to apply the parking brake several times, without touching the actual brake pedal. A neighbor with a 1991 Lumina learned this drill, and his brake problems went away."

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Keeping the rear brakes adjusted up *properly* prevents unnecessary pedal travel. Even a small amount of mis-adjustment from just one side will cause increased travel.

 

Sean is *right-on* with respect to the proper method of adjusting up the rears. Keep your foot off the brake pedal when pumping the Park pedal.

 

Aside from other issues that I discovered years ago shortly after purchasing the car this one item the owner can keep in check.    

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I recently bought my 95 Cutlass Convertible so I don't have a history with the car, but the car has, what I would call, terrible brakes. They stop me, and they will throw you forward in your seat a little if you two foot it, but I can't even get them to lock up, even on sand covered roads. I have said that if some animal was in the road, I would hit it because I wouldn't be able to stop fast enough. I have talked to the previous owner (who had the car for 17 years) and he said the car has always had a hard pedal with weak brakes. We have checked the calipers and they are all free. The car is supposed to have ABS but even under full brakes on a sandy road they don't kick in (probably because the tires never start sliding since they don't ever lock up). I did find a vacuum leak on the intake gasket so we will be fixing that to see if that helps, but I just want to make sure that I am not expecting something better than what I am ever going to get. What I have now just doesn't seem possible to be the way they came from the factory (but apparently is the way it has been for the last 17 years). Shouldn't I be able to actually lock the brakes up under a hard pedal?

Adjusting the rears does help with pedal travel and overall stopping distance. The inability to lock the fronts is not affected by that, however, unless you're bottoming your pedal.

 

First thing to check is the booster. Obviously, this is a vacuum booster, so vacuum leaks do reduce its performance. Keep in mind that the engine will run rough and idle high long before you lose vacuum brakes due to a vacuum leak outside of the booster. There are simple tests that you can find in most service manuals. These basically isolate check valve issues from booster issues and confirm booster ability to hold vacuum. They involve trying the brakes while you start/stop the car in a few different sequences.

In all reality, you will find some people on here who believe that the vast majority of our boosters are now dead and need R&R, not necessarily upgrades. I am not totally against that thinking, seeing how I cannot lock my fronts on totally dry pavement either.

 

Assuming you have the delco VI abs, there are cases where parts break inside the unit and cause poor regular brakes. Those instances are few and far between, however.

 

Also, do keep in mind that pad choice and rotor condition play a huge role. You would be amazed what people consider a brake job is. Without good (flat) rotor surface, decent pads, and freely sliding pins, your brakes will suck, even if you had the best booster ever made.

 

If I were you, given that you just bought the car, I would proceed by doing the basic booster checks and at least dismantle all the brakes to make sure all pins are sliding. Expect the rears to be seized and the fronts to be worn enough to replace.

I would also confirm abs function by testing it (safely) on a low friction surface. I know you say sand covered roads aren't enough for your brakes to overcome them. Maybe find a full on gravel road or ice somewhere.

 

If after all pins are confirmed sliding with ease, you are still unsatisfied with performance, consider replacing the booster anyway. Its mounting is somewhat funky in that it twist locks into place rather than bolts in, so upgrades always involve some fabrication, unfortunately.

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We have verified that all the pins are sliding just fine. I have done the basic tests on the booster (hold foot on pedal under moderate pressure and the pedal DOES fall towards the floor and then shut car off, wait one minute and push pedal repeated times and it DOES get harder each time and you hear the atmospheric valve relieving pressure when you press down). So the tests tell me the booster is okay (maybe okay is the key word, not great, just okay?). The car stops straight, doesn't pull to one side and all four rotors get hot when braking so it appears the brakes themselves are okay, I just don't have any real stopping power. The biggest thing is that the pedal just doesn't feel right to me, which makes me suspect the booster (even though it passes the basic tests).Totally confused.

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Yeah, I think I am just going to go for a new booster when I am am doing the intake gasket (I have heard it is way easier at this time). I can't find anything else wrong and while the booster passes the simple tests, who knows, maybe it is "kinda" bad.

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Yeah, I think I am just going to go for a new booster when I am am doing the intake gasket (I have heard it is way easier at this time). I can't find anything else wrong and while the booster passes the simple tests, who knows, maybe it is "kinda" bad.

Kinda bad is probably the issue with a lot of cars. The level of "kinda" is probably the biggest variable. That and driver tip-off point for replacement decision. Be sure to actually test the abs to eliminate that possibility first.

Also, feel free to report back! We'd love to hear results.

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How would I test the ABS? I have tried locking the tires up on a sandy road and the ABS never kicked in (nor did the tires ever start sliding).

 

One would make use of an ABS diagnostic scanner to test the system for function.

 

The scanner used would have to have the ability to activate & cycle the solenoids thru the test cycle, the ABS scanner is also used to bleed the system properly to remove any air that may get trapped in the modulator that can't be easily removed by bleeding at the wheel.

 

basic reading material below...

 

http://www.knowyourparts.com/technical-articles/brake-system-scan-tools/

 

http://www.techshopmag.com/abs-diagnostic-equipment/

 

In your 1st post you've mentioned that you've recently purchased the vehicle, not knowing what the previous owner had done for braking material installed to the car I personally would suggest going to a carbon-metallic pad at all four corners, they have better cold bite capabilities than ceramic does, the fade resistance is par to ceramic as well. The drawback to semi/carbon metallic pads is the harder wear on the rotors & the amount of dust up they produce & a possible squeak when lite pressure is applied to the pedal, but in my mind that is a trade off that is liveable given the performance they provide especially at the rears. 

 

Perhaps you might consider looking into this..... 

 

When at the parts counter have a close look at the friction rating of the material the pads are manufactured from......today most ratings will be in the area of either EE or FF or a combination of both. A GG rated pad is also becoming available as pad structure is evolving. These markings provide the cold & hot friction rating that the pad will provide when working in that temp zone.

 

http://faculty.ccbcmd.edu/~smacadof/DOTPadCodes.htm

 

http://www.knowyourparts.com/technical-articles/new-brake-edge-codes-explained/

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SAME PROBLEM HERE TOO. I had just bought this 92 cutlass supreme convertible, it to has about a 1 inch play on the pedal "normal" and then a dead hard pedal...I thought was weird too. They said they did a brake job, clean fuild, it might be the carbon brake pads, I had a set like that on another car and took it back after the brake job because it felt the same way...no braking power.

 I don't have abs written on the brake pedal, but did notice the parking brake pad on pedal almost completely worn off....I thought weird too, since I never use the parking brake unless on a incline, then I learned about pumping the parking brake...it must have something to do with it.

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I did it to my Z34 and I used a 1/2 inch diameter hose. Bought 2 feet since they round to the nearest foot but in my situation it's the check valve. If I move it then the brakes are better but they go back to crap after I turn it off and let it sit. I have to move the check valve again. I'm going to change my booster simply because I want to upgrade to the 94+ one. I always liked the brakes on my Cutlass vert.

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