'00 GAGT Vibration at high speed/shaking at high speed braking

[x_orange90_x]

Hello all. I have a 2000 Grand Am GT that I am having some troubles with. Recently I have put all new calipers, new front pads, new front drivers rotor, and a new passengers LCA. I also have newer (used) set of tires, put on about 3 weeks ago.

This past weekend I had to take an 1 1/2hr trip on the eway. when I get up past 65mph I begin feeling the steering wheel vibrate and can feel the front end vibrate as well. This is not constant, sometimes it will feel smooth for a minute or so and then go back to vibrating. Also, when vibrating I can feel it pulling to the right. While traveling 65mph+ and applying the brakes, the car starts to shake very bad until I am below 50mph or release the brake. If I apply the brakes gradually it shakes until one of the previous mentioned things happens, or if I apply them quick it will not shake as violently.

I have searched the web, asked family and friends, and asked some people at the parts stores. I've been told its a bad rotor, worn tie rod(s), or a wheel out of balance. Could a bad rotor cause vibration at speeds without braking? I've read that tie rods won't cause shaking or vibration unless they are very bad, but the front end feels tight at lower speeds. Lastly, can an out of balance tire actually vibrate the car and suddenly stop for a short period of time? Can it even cause shaking when braking?

I am not sure where to start here, but I do need to get it taken care of as I am supposed to be taking a 250 mile trip to Niagara Falls in a few weeks. Thanks in advance for your replies!

[[ChaosweaveR]]

I have to point out, for starters...why the hell would you only replace one rotor? The difference in thickness is going to give you a pull and that other rotor is more than likely warped.

There's a good chance your wheels are out of balance, or the tires are out of round. Main reason why I stay the hell away from used tires. A tie rod doesn't usually give you a vibration, warped rotors can cause vibrations if they're bad enough.

[x_orange90_x]

Thanks for the reply! Lol, I knew that was coming! I only replaced the one because it was very bad from a seized caliper, and because the other one looks to be newer anyways. But I guess neither is really a good excuse! So you think its the rotor causing shaking when braking and the wheel/tire causing the vibration?

I will stop by Discount Tire and have them check the tire balance for me. I can replace the other rotor as well, but I need to go get new caliper bracket bolts first. These bolts are my worst enemy as they are ridiculously tight and the heads round off easily, as mine have started to do

[[ChaosweaveR]]

The other rotor was probably warped due to the strain the non seized caliper was applying to it since the other side was not working properly. How many miles on the new rotor have been done?

The colprit is most likely either the wheels being out of balance and/or the bad rotor. If you can, observe them doing the wheel balance to see if the tire looks out of round or if you have bent/deformed wheels.

[Starglow]

Originally Posted by x_orange90_x

I will stop by Discount Tire and have them check the tire balance for me. I can replace the other rotor as well, but I need to go get new caliper bracket bolts first. These bolts are my worst enemy as they are ridiculously tight and the heads round off easily, as mine have started to do

Make sure you're using a metric socket for those bolts because if you aren't then that's why the heads are rounding off unless they're really rusted in which case they should be replaced.

[x_orange90_x]

Originally Posted by Starglow

Make sure you're using a metric socket for those bolts because if you aren't then that's why the heads are rounding off unless they're really rusted in which case they should be replaced.

yep, they're 13mm. It appears they were removed before I got the car and the rounding started at that point. To even get them off I had to beat the with a hammer to mushroom the head out to have something to grip with the socket. My brother said Menard's should have the right bolts, so I will go there to see.

[AaronGTR]

With brakes, when you replace pads and rotors you should do both sides together so they are even. That's probably causing part of the problem right there. It's also possible that only replacing the one LCA could be an issue, ie new bushings on one side and the other side they may be failing or just older and softer. That could cause a pull. Also using used tires... might have one that has a bad belt or is worn unevenly which could cause vibrations/pulling. I never get used tires, it's just not worth it. It's also possible that they might not have done a good job balancing them when they were mounted.

[x_orange90_x]

Thanks for your reply. As for the brakes, I know I should've replaced the other rotor I will be doing this shortly. With the LCA, I replaced the passenger one and that's the side that's pulling. That's also the side that the rotor was not replaced on, so I imagine the rotor is the cause of the pull to the right. I've noticed no matter the speed, if I brake too fast or hard, the pull begins after that. If I brake lightly and over longer distances the car continues to drive straight.

I've never really had any issues when getting used tires. This set in fact are Uniroyals that were pulled off of a PT Cruiser when the guy replaced his rims with a smaller size. As for condition they have very even tread and much of it, at least 75%. I have had a bad tire on a different car in the past and know how that is.

I appreciate all of the help and suggestions you guys have given! I will go get the tires and wheels checked, along with replacing the passenger side rotor.

[[ChaosweaveR]]

A PT Cruiser? You have the wrong tire size, bub.

PTs use a 205/55 R16 tire, the GAGT needs a 225/50 R16. Get the right sized tires.

[AaronGTR]

Also, if you did suspension work (like replacing a control arm) you have to get an alignment done. Your alignment could be off. Really, even if you don't have any work done you should get it checked once a year. At least the front end. It can change over time and getting it corrected can help your tires and bushings last longer.

I'd replace the other brake rotor and the other LCA you didn't do, and get an alignment.

[x_orange90_x]

I got 205/55 because the 225/50s are very hard to find in a used set. Discount Tire lists them as alternate tires for this car, so I didn't see an issue with it. And the reason I didn't go for new tires is I only paid $1000 for this car, so I wasn't looking to immediately spend $400 on tires.

[[ChaosweaveR]]

Originally Posted by x_orange90_x

I got 205/55 because the 225/50s are very hard to find in a used set. Discount Tire lists them as alternate tires for this car, so I didn't see an issue with it. And the reason I didn't go for new tires is I only paid $1000 for this car, so I wasn't looking to immediately spend $400 on tires.

You're missing the point. 205/55 R16 is too small and is the incorrect load rating for the suspension/weight of the car. It's throwing off your speedo.

Doesn't matter how "cheap" the car is, tires is something you do not skimp on.

[x_orange90_x]

Idk how accurate this calculator is, but according to it both tire sizes make 811revs/mile and the difference is only 0.1% between them.

http://www.miata.net/cgi-bin/tirescgi

And this one shows about .04mph difference

http://www.csgnetwork.com/speedocalibcalc.html

[x_orange90_x]

Ok, so I've been thinking about it alot and I think I may know exactly what's wrong with my brakes. Now someone stop me if I'm wrong, but it makes perfect sense to me.

I think the passenger side rubber brake hose is internally collapsed. Now here is why I think this:

When cruising at normal speeds from sy 35-55mph and braking lightly, I have no shakes or pull. After releasing the brakes and taking off again, the car wants to start pulling to the right. Eventually it stops pulling, IF I am driving for a bit without reapplying the brakes somewhat heavy again.

As for driving at 65+mph, it will cruise straight as I said, but as soon as I apply the brakes even slightly, the car shakes horriby until I release the brakes again. But if I brake harder the shaking stops. After this the car begins pulling to the right and I start feeling the vibration I earlier noted. I think that the alleged collapsed hose is restricting the flow to the passenger caliper making it not grab at the same time as the drives side. The drivers side grabbing alone I feel is causing the horrible shaking. Then if I press the brake harder, I think it's forcing the passengers side caliper to close, in turn making the shaking stop because now both calipers are gripping at the same time. Then after releasing the brakings, the hose keeps the caliper from releasing fully causing the car to pull to that side. The vibration I think is a result of the caliper not fully releasing and constantly dragging. Also, when the car does pull to the right, when rear cars or curbs and buildings i can hear the passengers side pads rubbing.

What do you guys think? Obviously I should still replace the other rotor, but now I don't think its the fault of all of this shaking and vibrating.

[AaronGTR]

Nope. Brake hoses don't collapse. They are too stiff and there is usually just pressure in them, not suction. That would be a sticky caliper piston causing that. If the piston doesn't return all the way easily it keeps the pad in contact with the rotor and creates drag which effectively pulls the car to that side.

[kzulfic]

Originally Posted by AaronGTR

Nope. Brake hoses don't collapse. They are too stiff and there is usually just pressure in them, not suction. That would be a sticky caliper piston causing that. If the piston doesn't return all the way easily it keeps the pad in contact with the rotor and creates drag which effectively pulls the car to that side.

Could be a caliper slide that isn't lubricated properly too. Seen people overlook those a lot.

[x_orange90_x]

Thanks for the reply. I've read many articles and posts about this happening and how the problems were gone after changing the hose. I'm sure there isn't really any suction, but rather a relief of pressure and fluid back into the master cylinder. A bad hose restricting the flow backwards would keep the piston extended, wouldn't it?

Anyway, this is a brand new caliper with brand new pins and clips and fresh grease. Is it really likely that the caliper is bad? The rotor and wheel are not any hotter that the rest of the wheels nor does it exhibit the grooves that the drivers side did after the caliper seized over there.

I don't know, all of this is very frustrating. I need to fix it before my trip.

[AaronGTR]

I've never heard of a collapsed hose causing a piston not to retract. At least not on this forum for these cars. They are made of pretty stiff material and like I said there isn't any suction in the line. You don't really get all that much quantity of fluid moving back and forth either when the brakes are applied/released. The caliper piston doesn't move that far. It just gets a lot of pressure from the master cylinder piston (transmitted through the brake fluid in the lines).

If you've already replaced the caliper though I guess it can't hurt to replace the line if they are old. Most times people end up replacing the lines because the rubber gets old and starts to expand too much (brakes get soft) or cracks and they don't want a fluid leak or the line to blow out. So if they are old and you can find some for a good price, go ahead and replace them. Make sure you do both sides though. Also make sure you lubed the caliper bolts with enough of the proper type grease. Like Kameron said, a lot of the time people with stuck caliper just didn't grease up the slider bolts and they hang up.

[x_orange90_x]

I found that AutoZone has the hoses for 7.99ea, so for under $20 that's not a bad deal to do both sides. I will also recheck the slides as well.

Something interesting though is that I've had this pull even before replacing the calipers. First I thought it was the LCA, but the pull persisted even after its replacement. The LCA did need replacing though because the bushing became ****ed in on an angle and caused a slapping sound when braking heavy. I know for a fact though that while I was working on this, at least one time the caliper fell and hung by the hose. The caliper was resting on the wheel which I had slid under the front end. I've read its bad news for the hose if this happens.
So maybe that explains somethings..

[AaronGTR]

Well, Like I said earlier... if things aren't the same on both sides, and if your alignment is off, you are going to have a pull.

Replace things on both sides at once when you get them serviced. Don't just replace one LCA. If one side is bad, the other is probably going bad as well, or is worn and the bushings are weaker than on a new arm. When you do brakes, replace pads and/or rotor on both sides at the same time. Try rotating the tires, make sure to rotate them on the recommended schedule, and get them rebalanced if needed. And get an alignment done. Then you shouldn't have any pull.

Cars are complicated machines, and they require constant, consistent maintenance to staying running properly. If you keep up with it they will run for a long time though.