Today after hitting the brakes rather hard going from 70 to 20 in a deceleration lane, I made the turn and started to accelerate when I hear a rather loud knocking/thumping noise near the front left wheel. The thumping decreased from slowing down and increased when accelerating. Tapping and stomping on the brakes couldn't get it to quit, so I had to turn into a driveway and come to a complete stop which then "fixed" the problem. I drove home and parked the car.

This isn't the first time braking has been a concern. In fact, braking a bit more than what I'd consider normal, I get a tad bit of shudder, the car tends to favor steering to the right (the wheel moves and is more difficult to counter-steer), and makes a noticeable deep noise that sounds like the pads are working overtime. The PO had drilled/slotted rotors installed but I saw nothing about replacing anything else other than new pads. The mechanic I take my car to looks at my brake pads each time I take it in and hasn't said if anything was out of the ordinary.

Anyone have any ideas on what could be happening and if I need to upgrade some parts? I'm not a mechanic in any way (I know) but I do know a few people who can get the job done and do some diagnostic work.

Thanks in advance!

Check your lugnuts - Swap your tires front to rear. See if this makes any changes

The hard stop might have overheated your rotor to the point that it warped, but after cooling the rotor went back to normal. A possibility.

[This message has been edited by phonedawgz (edited 07-14-2010).]

If the car is pulling to one side while brakeing,then it sounds to me like you have a sticking brake caliper.You can try this in an empty school parking lot,accelarate to 20 or so and briefley take your hands off the steeing wheel while brakeing normalley.See if the car pulls to one side.Shuttering may be caused by the sticking brake caliper, or you may have warped your brake rotar by brakeing hard.

[This message has been edited by James Bond 007 (edited 07-14-2010).]

quote Originally posted by phonedawgz: Check your lugnuts ...

Good suggestion. Could be any or all of the above, plus sticking/binding caliper slider pins. I would be cautious of the no-name drilled/slotted rotors, too.

[This message has been edited by Marvin McInnis (edited 07-15-2010).]

Sounds like the upper control arm is loose ad shifting when braking or taking off. This has happened to me twice on differant cars and would only hear ir during hard breaking....

When you made this hard stop did you lock up the front wheels? If so, don't discount that you flat-spotted a tire. All the other possibilities I could think of have already been posted.

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'88 GT- 3800 Turbo 11.367@121.03mph
gmtuners.com -Build info

Thanks for the replies, everyone. +1s for everyone. This will help a lot when I take the car in.

I didn't lock the brakes up, Akursed, so a flat spot on the tire couldn't account for the noise. The noise gave the impression that two pieces of metal were hitting each other over and over again. No jerking though, just a loud thumping noise. I'm kind of starting to point the finger at the caliper myself without knowing any better.

It is weird because it was doing its thing making noise, I pulled into a driveway, stopped and thought about it for maybe 10 seconds, put the car into Neutral, let off and then back on the brake and clutch (trying to "reset" it like how you would troubleshoot a computer, heh), reverse, and it went away immediately when I began accelerating. Could going in reverse have fixed it? Hmm.

If anyone else has any thoughts, I'd appreciate it!

[This message has been edited by zigaroo (edited 07-14-2010).]

Is your Fiero an '88? Check that all the caliper attach bolts are still in place and tight! Do it now! That thumping noise may be a loose caliper hitting the inside of a wheel. If it jams while you are moving, the damage is likely to be extensive, not to mention the safety implications. This is a problem that can affect all years, but it's especially common on '88s. There are lots of threads in the PFF archives on this subject.

[This message has been edited by Marvin McInnis (edited 07-15-2010).]

Marvin, when I read your post this morning I went outside and checked the caliper and it seemed sound, thanks for the heads up.

The mechanic found that the caliper was at fault and the rotor is warped. He also said the steering tugged to the right when braking (which is what I was experiencing as well, but I didn't tell him about the tugging when I took it in) and the brake hoses probably need replacing because of that. Whether true or not, they're original and I wouldn't mind stainless steel going in.

So now I'm thinking of replacing all four rotors, calipers, pads, and hoses to bring everything up to new status rather than having half new and half original.

I'm looking at Fiero Store rotors and their stainless steel hoses. What about calipers and pads? Thoughts and suggestions please?

What year is your Fiero? '88 brakes are different (and better).

Exactly how is your left front caliper "at fault?" (Not busting your chops ... just trying to determine if your mechanic knows what he's talking about. His advice so far doesn't seem very good.)

Concerning suggestions for replacement parts, I recommend that you restore the stock system to proper operation (using all good quality, OEM-style parts) before you consider any modifications. In addition to GM/ACDelco/Delphi, Wagner and Raybestos are two well established and dependable manufacturers of quality brake parts, although even they have recently moved some of their manufacturing to China. I think you will find the properly-working stock system to be a big improvement over what you have now.

[This message has been edited by Marvin McInnis (edited 07-15-2010).]

Didn't mean to keep avoiding that bit of info---yes I have an '88 Formula.

After researching some threads and taking what you said into consideration, I am going to buy TFS regular rotors (don't care for the drilled/slotted noise that my current ones create), TFS SS hoses, and go in and see if they'll rebuild the calipers. If they won't for some reason or foresee having problems finding parts (?) I'll just buy the rebuilt ones from TFS and send in my current set for a refund. Overall, it really won't be that expensive... thankfully.

Still need brake pads. Marvin, you made a suggestion in 2009 ( https://www.fiero.nl/forum/F.../HTML/100878.html#p2 ) to use Wagner "Thermoquiet" pads (MX378 part number). Would you still recommend these?

Thanks a bunch.

quote Originally posted by zigaroo: ... you made a suggestion in 2009 to use Wagner "Thermoquiet" pads (MX378 part number). Would you still recommend these?

Yes. Wagner MX378s are what's still on my car, and since their lifetime warranty includes wear I'll probably be using them forever (or until Wagner stops making them). I'm still 100% satisfied with them for street use.

The '88 front calipers are pretty easy to rebuild, but the last time I checked brand new '88 front calipers, already loaded with good-quality (ACDelco?) pads, were still available from www.calipersonline.com for not much more than the cost of rebuilts, and you get to keep your old ones. I highly recommend this option if you're going to replace your calipers anyway.

I would also suggest that you at least price Wagner and Raybestos rotors through your local auto parts stores. Don't get me wrong, TFS is a very good vendor of Fiero-specific parts, but when all else is equal I prefer to patronize local suppliers. if nothing else, warranty returns are a lot easier if you're dealing with a local store.

[This message has been edited by Marvin McInnis (edited 07-16-2010).]

Here is another option for brake hoses also...
http://www.summitracing.com/parts/RUS-692110
Russell part number 692110. Great product, great warranty.

[This message has been edited by Fieroseverywhere (edited 07-15-2010).]

I would gets these items if you want new brake rotors and new brake pads:
R1 Concepts premium performance Brake Rotors (Front and Rear cross drilled AND slotted )
-you can pick them up from Ebay(being the cheapest) brand new for around $220.00 or go to their website

I would recommend APEX carbon fiber brake pads
-they will cost you although around $90.00 (they produce virtually no dust and good for heavy peformance)

Otherwise get the carbomet brake pads from The FieroStore for around $60.00

If you wanted calipers too FieroStore has them for around 90.00 a piece

I am pretty sure you can get stainless steel brake lines from FieroStore.com also but i haven't checked yet


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1988 Pontiac Fiero Gt (has every option available from that year including factory leather, 5-speed, and the rare T-Tops: Black w/ gray interior and blk wheels)
1992 GMC Typhoon #0203
1971Chevorlet Corvette 454cu/ LS5/ 4-speed/ convertible
1993 BMW 850 Ci 6-speed V-12

[This message has been edited by gmctyphoon1992 (edited 07-15-2010).]

quote Originally posted by gmctyphoon1992: If you wanted calipers too FieroStore has them for around 90.00 a piece

Why would he want to do that when he can buy a pair of new (NOS) OEM '88 front calipers, with OEM pads, for $125 a pair?

ok whatever i was just saying that off the top of my head because i remember going onto fierostore.com to get calipers and seeing those for around 80 dollars a peice. The stock OEM pads are crap though trust me. I went through two sets of OEM ACdelco pads in a year (not even driving the car that hard or that much). They were terrible and they Emmit way too much brake dust for the stopping power it gave me.

quote Originally posted by gmctyphoon1992: The stock OEM pads are crap ...

I disagree. Apparently my experience with them is very different than yours.

[This message has been edited by Marvin McInnis (edited 07-17-2010).]