The very first thing that comes to mind...is a loose nut behind the steering wheel.:lmao:

 

Strange indeed, While I have converted to much larger disk brakes all around, It was done only for better braking efficency. I have yet to own a GT that had warped rotors.

 

I'm with Wrench. Manta has the same setup upside down, never seen or heard of warping these if installed properly and no one's riding the pedal.

 

Rotor distortion

Make sure you are torquing (sp?) everything to recommended specs.

All numbers in foot pounds from the 1973 factory service manual

Brake caliper to steering knuckle 72
Brake disc to wheel hub 36
Brake disc shield to steering knuckle and steering arm 47
Brake pipe to caliper 22
and wheel (lug) nuts 65

Also use the proper tightening sequence on your wheel lug nuts. If not, I have seen improperly tightened lugnuts warp rotors on other vehicles. Not sure if it would happen on a gt or not.

 

Ps

By the way, steering wheel jiggling all over the place might indicate worn suspension bushings...

 

Brake rotors become warped due to intense heat. As the pads and rotors are rubbing against each other they go hot. During normal driving conditions, the heat is eventually dissipated but the spirited driving can make rotors extremely hot. Then, when the car is stopped (at the red light or similar), the pads are sitting in one place of the rotor. The rest of the rotor cools off quicker than the spot where the hot pads are sitting. The result is a warped rotors.
Standard GT rotors are small as they have to fit 13" rims. Their relatively small surface will not dissipate the heat very well. Big brakes kit as discussed on the pages of this forum has rotors of larger diameter, i.e. larger mass and surface. They are also ventilated which makes them work cooler. Such rotors will last longer and brakes will not have a tendency to fade.

 

Brake rotors become warped due to intense heat. As the pads and rotors are rubbing against each other they go hot. During normal driving conditions, the heat is eventually dissipated but the spirited driving can make rotors extremely hot. Then, when the car is stopped (at the red light or similar), the pads are sitting in one place of the rotor. The rest of the rotor cools off quicker than the spot where the hot pads are sitting. The result is a warped rotors.

Yeah, I always try to take the time to let my brakes cool off a bit after a bit of "inspired driving" if I know I'm entering a town or something, say just coasting the last mile or two before I hit traffic lights and stop go traffic

That said, a lot of after market wheels aren't exactly made with brake cooling in mind and does nothing to improve the air flow through the wheel well, something to consider before buying something like a classic Centerline wheel with a solid center. Personally I prefer the aesthetics of a more "open" design but those who like the classic closed, deep dished look may need to consider improving the air flow to the brakes to compensate

Same with front spoilers, a lot of them have openings for air ducts for a reason, to let you channel air to the brakes because of the loss of air flow in the area due to the spoiler

 

There has been some question of the validity of rotor warping. Apparently, years ago, some fairly well known people investigated this issue and found that what was thought to be warping was actually minute amounts pad material (not enough to see) transfering to the rotor. Probably as a result of getting the brakes really hot just before coming to a halt and holding the hot pads in contact with the hot rotor.

Plus there is the matter of pad and rotor material compatibility.

 

Talk me into it.

I think that what I'm actually trying to do is to get you guys to talk me into upgrading to Big Brakes. I only started doing my own brakes in recent years. All my bushings are new. Several other mechanics at a very highly regarded local repair shop did the bulk of my brake work over the past 30 years. So, unfortunately, I can't solve the problem simply by replacing the knucklehead behind the wheel.

I can say with certainty that all of the warping incidents occurred after a rapid slow-down at highway speed. I almost count on it to happen. It's happened on 5 different cars.

I didn't know that you could get the ventilated type of rotor with Big Brakes. I've only been able to get cross-drilled and radius-ed rotors for oem brakes and even those fit really tight between the pads. Do Big Brakes accept a thicker rotor that can be a ventilated type like PJ's pic?

 

I didn't know that you could get the ventilated type of rotor with Big Brakes. I've only been able to get cross-drilled and radiased rotors for oem brakes and even those fit really tight between the pads. Do Big Brakes accept a thicker rotor that can be a ventilated type like PJ's pic?

Cross drilled rotors do little or nothing for the temps of your brakes and if you think about you'll see why. You are converting one form of energy into another, namely the movement energy of your car into heat by the use of friction. A solid rotor has more mass than a similar sized cross drilled rotor and can therefor accept more heat before it gets over heated. The cross drilling does not allow much heat to dissipate anywhere, what it does is allow the gas that builds up between your pads and rotors to slip into the holes so it has somewhere to go but that's a very minute amount, this allows your pads to work more efficiently but on the other hand it also reduces the contact surface between your pads and the rotors which in turn means your pads and rotors has to accept more heat in the surface that's available. The holes are also a starting point for cracks

Cross drilled or slotted rotors are fine if you're not already marginal on the temperature of your components, if you are then it's my opinion that you're making things worse, not better, with cross drilled rotors

I've learned a lot about brakes from reading Fred Puhn's "Brake handbook", ISBN 0-89586-232-8, and while I'm sure it's not the definitive book about brakes it's pretty good as far as I can tell

BARNES & NOBLE | Brake Handbook by Fred Puhn, HP Trade | Paperback

The best solution of course is to go for vented rotors and it's possible to do so and still use 13" wheels, if that's what you're using. I'm in Europe so my solution would have been to use the brakes from the Opel Rekord 2.2i, but I seem to recall that Juan has posted in here about using parts readily available in the US

 

By any chance, do you notice the rotors "warping" just after it comes out of winter storage? Or do you drive it year round on a regular basis?

 

It does come down to over heating. If the rotor cools at different rates from an extreme elevated temp they warp. Which is the experience you have. The vented rotors have more mass thus allowing more friction energy to be generated while keeping the rotor temperatures lower. They are also thicker which makes the rotor stiffer and resists warping.

It is apparent that the stock brakes will not serve your need good luck on the upgrade!

 

As Wrench as already stated, it's probably you. :yup: Some driving styles tend to be harder on brakes than others. I've done more brake jobs on our old Buick than any vehicle I've ever owned. Wife's a good driver and I've never had that problem on anything else see has driven and it didn't get any better when the youngest daughter took it over. :sigh:

My experience with Opel rotors warping was usually caused by the calipers dragging. But lots of people with A/T, old folks and city folks, seem to 'ride' the brake pedal more than folks with M/T's.

Harold

P.S. Buick (RIP) has recieved it's last brake job from me. :sad:

 

My next GT mod...

...will be the brakes from a Suburban. My '03 has 203K miles and, I kid you not, still has the ORIGINAL brakes! And they are not even close to needing replacement! And that's with my WIFE driving it from 17K miles! I don't know how that is even possible but that's the kind of performance I want for a GT. I'll probably have to use the whole front end....
:lmao:
vancek

As Wrench as already stated, it's probably you. :yup: Some driving styles tend to be harder on brakes than others. I've done more brake jobs on our old Buick than any vehicle I've ever owned. Wife's a good driver and I've never had that problem on anything else see has driven and it didn't get any better when the youngest daughter took it over. :sigh:

 

I use brakes only as a last resort

I came of driving age in 1976, when there were government sponsored commercials on tv that urged you not to waste gas by using the brakes a lot. The ads urged you to anticipate your slow downs well in advance and ease off on the gas pedal early instead slowing by braking. I also live in a heavy traffic area with lots of reasons for last second or emergency braking. And, yes, I drive my GT like it's a supercar and I tend to hit the brakes hard at the last possible moment.

I'm actually really surprised that no one has come forward with frequent warping syndrome stories.

I have 15" wheels, so going bigger shouldn't be a problem. Can anyone hook me up with all the goodies I'll need(expansion kit, vented rotors, etc.)? I just love buying new toys for my buggy!:yup:

 

this fitting new brakes then going out and doing a load of high speed stops intrigues me !!

total opposite of what i have always been taught to do with a European car

we are told to treat them gentle until they bed in not abuse them to bed them in , this may be the problem

other thing that comes to mind is this is an open family forum so are some of the words in the first post really what should be posted ? Moderator Note: Taken care of. HC

thanks Harold

 

Opels have brakes???! Hmmm......I thought that's what downshifting was!! :drive:

No warping on mine ever .......

 

I've started off with brand new everything, including pads, lines, and fluid, and gone out and done 8-10 rapid slow-downs from 70-80mph and the darn rotors are warped in one day.

You gave the reason right here. Wayyy too severe a break-in procedure. Even with competition pads you need to break them in far more gradually. And you need to give them time to cool off. If you park the car after your break-in you will likely heat-soak the rotor directly under the pad area. This will cause a localized warpage.

You need to do maybe 10 moderate (not severe, not like an old lady either) slow downs from about 35 mph. Don't come to a complete stop. Then keep on driving for 15-20 minutes, avoiding using the brakes at all. Follow up by doing another 5-6 slow downs (not complete stops) with near-threshold braking force, but this time from 50-60 mph. Continue to drive for another 1/2 hour with minimal brake applications to let the pads and rotors cool gradually and evenly. Park the car overnight. Re-bleed the brakes the next day. You're all set.

 

I was going to comment that your bedding in process sounded pretty severe. Like Bob noted, getting some heat into the pads using 35-45 mph braking is generally recommended.

We warped our rotors during our first race. These were the 40+ year old rotors that came with the car, but we had them resurfaced before the race. After the race we resurfaced them again and they served us well for 5 more races. We just retired them due to grooves and thinning.

By the way, we really cooked our brakes at the last race, destroying the dust boots, bending the pads, and even damaging a caliper seal to the point where it was leaking. But the rotors were fine other than the accumulated wear of a year of racing.

I have this idea that warping of rotors may be related to the casting process, especially the uneven cooling of the casting, leading to residual stresses, the kind that cryo-treating is supposed to deal with (but doesn't). Reheating the rotors, if they get hot enough, could affect a stress-relief treatment and result in slight distortion. After resurfacing they should be good from there on out. But, that just an idea I've had in my head for a while. I don't have the data to back it up. So just ignore me.

 

Just to throw this out there.
I have run across a set of bad rims that warped the rotors. Guess that the flanges were not correct. IDK:dunno:

 

Don't recall anyone mentioning that the greater the rolling mass, the more demand that is placed on the brakes. So if those aftermarket wheels a lot of folks put on their vehicles weigh substantially more than the original wheels do....:yup:

Harold

 

Harold i think the wheel bearings would have to be so shot as to be unusable for wheels to be bending the discs as even a heavier wheel and disc would still be straining the discs in their correct plane with good bearings as they take the weight not the discs

think we can just put this one down to the bed in procedure used

 

Harold I think the wheel bearings would have to be so shot as to be unusable for wheels to be bending the discs as even a heavier wheel and disc would still be straining the discs in their correct plane with good bearings as they take the weight not the discs

Wrench's post I 'assumed' was referring to the fact that rotors will sometimes warp from the uneven clamping force caused by uneven and/or over-tightening of the lug nuts/bolts or that the surface of the wheel that mates to the rotor might not be true enough and cause the rotor to warp.

The greater the rotating mass, the more heat that will be generated when braking unless the brakes are upgraded. Most of our cars came with 13"x5" steel wheels with 165SR 13 tires mounted on them. I would guess the typical 15'"x7" alloy wheel and 205/50 HR 15 tire and combination some folks upgrade to is probably going to weigh more. Simple physics, more power is going to be needed to accelerate at the same rate as before and more energy is needed to decelerate at the same rate as before.

think we can just put this one down to the bed in procedure used

:biggthump but there may still be contributing factors.

Harold

 

This may not apply in your case, but for future viewing of this thread...

When replacing the pads, never let the calipers hang by the rubber hoses. The hoses stretch and split on the inside causing a flap that acts as a check valve which doesn't allow the caliper piston to retract quickly enough.

I learned this lesson years ago when I thought a warped rotor was causing my car to shimmy when braking. :banghead:

It's always a good practice to replaced the rubber hoses during major brake repairs.

 

I'm really not the nut-case I portray myself as

I know I make it sound like all I do is floor it all the time and powerslide through every turn, but it's nowhere near the truth. I do plenty of low speed driving with lots of calm rational braking.

I think Gary might have hit on one of the causes that might have plagued me in the past. The hoses swelling and blocking the brake fluid flow which could cause the shoes to drag excessively and heat up my rotors. I only learned about the problem during the past few years being on the website here. I never replaced those lines on my previous cars. My present car, which has new lines and hoses, fluid, rear cylinders, pads/shoes, and rotors still has used rebuilt front calipers and master cylinder. I think, maybe, that one of the caliper pistons might be hanging up and caused a rotor to warp.

That's one reason why upgrading the front brakes sounds appealing to me. If I have to buy new front brake stuff, I might as well upgrade. Plus, buying cool new stuff for your Opel is always a good thing.:yup:

I gotta drive to Oklahoma this weekend for 3 weeks of job training, so I won't be able to investigate the brake issue until the new year.

 

I'm really not the nut-case I portray myself as

Bro I love your posts.
They have made me chuckle more then once! Almost as much as Cory's World.

 

Hi Gordon,
Just my 2 cents here. I believe RallyBob hit the nail on the head, too hard on the brakes at your initial break-in. I've driven my GT for about 20 thousand miles or so and have not experienced any warping. (car has 100K on it now. Current brakes were from the previous, original owner who had the brakes done at a local garage in CA). Vibration from worn rubber bushings, yes. But nothing when I hit the pedal. Having said that, do splurge for the big brakes, front and rear. I believe you'll need a rear proportioning valve for the rear brakes if you go with the Opel big brake set up. I do have my thoughts and doubts about modern day metallurgy, especially if the rotors we purchase come from another country other then Germany.
Take Care,
Mike

 

Years ago I was amazed to see torque sticks used with an impact wrench.

They turn the lugs up to the rated torque then absorb the twisting force of the impact wrench. They are even color coded. Cool stuff.

 

Gordon,
Good luck with the new set up and of course, we'll need a road test report......May I recommend you not do the 70-80 mph rapid slow down procedure to bed in the new pads!
Take Care,
Mike

 

Ooops, my bad....

Well, I started putting my brand new brake system in and whilst adjusting the bearing tension after installing the vented rotors I couldn't get rid of the rattle on the right front side. Lo and behold my tie rod joint was wobbling all over the place! It was perfectly fine just 2000 miles ago when I bought the front end already rebuilt from a member. I didn't hit any pot holes or have any incidents that I could attribute it to. I was wondering why the rotors that I thought were warped didn't show the slightest imperfection.

Oh well, at least I'm not the crazed psycho brake pedal squasher y'all thought I was. But I am the same knucklehead that most of you already know I am.:yup:

 

... Lo and behold my tie rod joint was wobbling all over the place! It was perfectly fine just 2000 miles ago.... I was wondering why the rotors that I thought were warped didn't show the slightest imperfection.

Oh well, at least I'm not the crazed psycho brake pedal squasher y'all thought I was. But I am the same knucklehead that most of you already know I am.:yup:

Well the mystery is solved....both of them :haha:

An in depth report of the new brakes is still needed...when you get the time of course.