[Ibz82]

So I was driving the other night and stopped at a friends where there was a large puddle with a pot hole!!!! As I drove thru it the water must of came in contact with the disc because there was loads of smoke coming from them wtf! Now when I'm braking my steering is real shaky. Are my discs warped? First time I ever had this kind of problem! What u guys think?

[Russbmw]

Doubt it.

More likely that you've buckled the wheel or lost a balancing weight.

[Jamie_E92]

as above the pothole wont have come in contact with the disc, it'll have more than likley buckledd the wheel.

[xenon]

I very much doubt the OP thinks his disc has hit the pothole. I suspect he's asking if the sudden dunking of freezing water on a hot disc can cause the disc to warp or crack, which it can.

If it were a buckled wheel or a missing wheel weight then the problem would be apparent all the time not just under braking.

[AdamN52]

I doubt your rotors would warp from that... but for that much smoke/steam to come off I would think maybe your brakes have been dragging? Or else you just drive like a madman. lol

You probably bent a rim. Do you notice any steering shimmy/vibration when you're at hwy speed?

[xenon]

Even driving normally throwing water over your brake discs generates a lot of steam. Stopping a 1.5t car from 60mph will heat the discs to over 300 deg C.

[Jamie_E92]

Originally Posted by xenon

I very much doubt the OP thinks his disc has hit the pothole. I suspect he's asking if the sudden dunking of freezing water on a hot disc can cause the disc to warp or crack, which it can.

If it were a buckled wheel or a missing wheel weight then the problem would be apparent all the time not just under braking.

You never know, there are a lot of retards on here of late. (not suggesting you are a retard btw OP)

And thats a bit of a bold blanket statement to make, I've had it in the past when the only apparent sign of the buckled wheel was braking from speed. So your wrong.

[xenon]

Explain how that works then. A wheel is buckled but only shows vibration as it begins to slow....

[Jamie_E92]

Originally Posted by xenon

Explain how that works then. A wheel is buckled but only shows vibration as it begins to slow....

Not being a physician, i can't help you - just showing my findings, are you calling me a liar?

[Russbmw]

Hey, easy people.....it's all speculation without knowing how deep the puddle was, how big the hole was, etc - and the decription of when the vibration happens is pretty vague. Braking from what speed would help for starters.

FWIW Ian, you know I value your opinion and you've helped me out a few times in my time here, but IMO it's highly unlikely that the disc getting wet would warp it. It's a thick lump of metal for starters, it'd take quite a lot to warp it - and warping is usually cause by excessive heat build up from hard braking, then keeping the hot pads pressed onto the hot disc.

Look how much rain we've had recently, roads are flooded everywhere. I've ridden my motorbike through water up to my footpegs, both mine and my wife's cars have had to become practically amphibious vehicles at times, and not one vehicle has had warped discs as a result.

If discs warped when they were used/hot and got a bit wet, then people's cars would be fucked every time they went to a car wash.

I could perhaps see it happening if the calipers were sticking and the brakes were literally red hot then got quenched (by which point the OP would have noticed brake fade way before vibration!), but not under normal use.

My old e46 had the rear shoes disintergrate, causing the rear brakes to get hot enough that the alloy itself was warm/hot to touch. I didn't realise, and it was only when I was hosing the car down 5 mins after I got in that I had steam pouring off when the wheels got a soaking. Never damaged/warped anything.

[xenon]

A physician is a doctor of medicine so not entirely sure how that's relevant. No, I'm not calling you a liar as I don't know you from Adam. I was just wondering how a buckled wheel would cause the symptoms you described - as it happened to you I thought you might be able to explain.

[xenon]

I agree Russ - I very much doubt the discs are warped, I'm not even convinced a casting will warp without cracking, but it is possible. Could be a number of things that's caused the OP's problem.

[Jamie_E92]

From many an e46 i've owned, they can tramline & shudder under braking simply from the different brands of tyres that are fitted!

You asked me to explain my findings, I can't explain them, simply, I had the wheel put on a balancing machine after experiencing vibration under braking & it highlighted the wheel was buckled, this wasn't apparent whilst under normal conditions, only under braking.

I'm only trying to help the OP , not to have an argument with someone 'i dont know from Adam'

[Russbmw]

No a casting won't warp.

Quenching from different temperatures will change the metal crystal structure and phases, etc. Which will affect the physical properties (toughness, hardness, etc), not warp it. (yes, metallurgy was one of my modules at Uni 20 years ago...yawn).

[xenon]

Fair enough Jay325i.

[Jat]

I believe, but may be wrong, that if you had/have a warped disc, you would feel a pulsing through the brake pedal when applying the brakes.

Do you get this?

Have you checked the rims and tyres for damage, cuts, bulges from the sidewall etc?

[Jamie_E92]

Apologies if I came across as a bit of a nob, it just got my back up a bit suggesting I was lying, you seem a very helpful & informative member Ian, so not taking that away from you.

[Russbmw]

OT - sorry. Jat, is that Kav's old 330 touring?!

[AdamN52]

Originally Posted by xenon

Even driving normally throwing water over your brake discs generates a lot of steam. Stopping a 1.5t car from 60mph will heat the discs to over 300 deg C.

I don't disagree that brakes generate a ton of heat, but I feel that they would have to be abnormally hot (like the car was at the track, or brown-pant braking or something) to warp when exposed to water.
Not saying it's not possible, but I think it would be rare since a design consideration of rotors is being exposed to the elements.

That being said this topic seems to have gotten rather heated as well...

OP: try driving at different speeds and note if you feel any shimmy in the steering wheel when driving, and also when braking.

Then you could try swapping front/rear wheels and repeat the test.

• If the vibration moves from the steering wheel to the seat - you've got a tire/wheel issue.
• If the vibration stays in the steering wheel it's something in the front end (rotors/bushings/bearings/whatever)

[Russbmw]

The OP needs to elaborate on the incident, and also on what happens now and under what conditions IMO.

It's easy to damage bushes and suspension components on potholes for starters.

It might be the vibration only occurs when braking from 70 down to 40 and then stops - which is more likely to indicate a balancing issue - but without more info, it's kind of guesswork.

From experience, a buckled wheel - particularly if it's only on say the inside edge, can give the same effect as an out of balance wheel in as much as it will only cause vibrations at certain speeds, although that doesnt' explain why it apparently only happens when braking, I admit.

FWIW, I'm not far from Epsom and if you need someone to have a look, let me know. I can change discs/pads cheaper than a garage if you need it!

[AlanYoro35i]

OP- Just get checked out...

[Ibz82]

Originally Posted by xenon

I very much doubt the OP thinks his disc has hit the pothole. I suspect he's asking if the sudden dunking of freezing water on a hot disc can cause the disc to warp or crack, which it can.

If it were a buckled wheel or a missing wheel weight then the problem would be apparent all the time not just under braking.

Spot on