The mystery of the warping rotors....

[PeterH]

After about 6 months of owning my P38, I noticed the brake pedal pulsating during braking, which spelled warped rotors, so I put some newwies on, decent aftermarket ones and all good.
Fast forward another 18 months and once again, pulsating brake pedal.
Thinking they may have been crappy quality rotors, I fitted another pair of decent aftermarket ones, (bearmach I think), and all was well once again.
2 years later and it has happened once again...grrr!
I drive and brake fairly gently, so I'm not jamming the brakes on hard by any means.
It's always the front ones, rears seem fine.
So what gives...any thoughts on what might cause this?
Should I spend the extra and fit genuine rotors?
Cheers, Pete.

[rangieman]

Had this problem with holden cars mid to late 90,s due to asbestos free pads , They suffered all sorts of brake shudder due to the pads with out asbestos.
So what pads are you using ? city driving mostly?

[wayneg]

Dont know why you have this issue however I have recently fitted all 4 new rotors to my car. Got them from ebay Oz a business seller in Qld. just over $200 the lot for genuine Brembo rotors and a free set of rear pads thrown in.

Heres a link for the fronts both for A$97 shipped,
http://www.ebay.com.au/itm/PAIR-FRONT-BREMBO-DISC-BRAKE-ROTOR-RANGE-ROVER-II-4-0L-4-6L-2-5L-TD-1995-01-/161164920221?pt=AU_Car_Parts_Accessories&hash=item25862d859d

Have a read of this, could be plausible...........http://www.examiner.com/article/there-s-no-such-thing-as-warped-brake-rotors

[landrover dave]

After about 6 months of owning my P38, I noticed the brake pedal pulsating during braking, which spelled warped rotors, so I put some newwies on, decent aftermarket ones and all good.
Fast forward another 18 months and once again, pulsating brake pedal.
Thinking they may have been crappy quality rotors, I fitted another pair of decent aftermarket ones, (bearmach I think), and all was well once again.
2 years later and it has happened once again...grrr!
I drive and brake fairly gently, so I'm not jamming the brakes on hard by any means.
It's always the front ones, rears seem fine.
So what gives...any thoughts on what might cause this?
Should I spend the extra and fit genuine rotors?
Cheers, Pete.
Brake warping is caused mainly by incorrect tensioning of wheel nuts. Top hat rotors rely on the wheel nut tesions to hold them in place, incorrect tensions will pull them out of round. It only needs a couple of thousands of an inch, of uneven wear, to cause a brake pulse.
When the rotors are out of shape, the pads wear a little off the "high spot". This can only be measured accurately with a dial indicator.
Remedy is to machine the rotors, or replace, make sure the mount surface is clean and rust free, and TORQUE WHEELNUTS TO MANUFACTURERES SPECS!
Pulsing through pefal only is generally rears, through pedal and steering wheel is front or both front and rear.
This is a common problem with any top hat rotor thatr relies on wheel nuts to hold the rotor in place! DO NOT RELY ON RATTLE/AIR IMPACT GUNS AS THEY WILL NOT TIGHTEN WHEEL NUTS EVENLY

[Keithy P38]

P38's don't rely on wheel nuts to support the wheel, the rotor has a spigot that centres the wheel when you put it on.

I'd suggest nuts that have been put on and tensioned unevenly (ie, first nut is put on and tensioned before another nut is put on) would cause this drama, but you'd notice it before 2yrs is up...

EDIT: P38's have nuts like any good car, that screw on to studs.

EDIT #2: Re-read your post, thought you were talking about wheels requiring nuts to locate, but you were in fact talking about rotors being pulled unevenly by incorrect tensioning. My bad!

[PeterH]

Very interesting read there wayneg, also interesting replies too, some agree, some disagree.
I have never tourqed the wheel nuts before, but will be doing so from now on!
I always do them up in the 'star pattern' to evenly distribute the tension, and give them all about the same force of tightening with a breaker bar.
Interesting that I have never seen a tyre shop do up the wheel nuts with anything other than a rattle gun, I'm guessing they must have the guns set to a ballpark tension for all vehicles.
Looks like I'm up for a new set of rotors once again, hope tourqing the wheel nuts sorts the problem out.
Thanks for all the replies.
Cheers, Pete.

[Outback 1]

Very interesting read there wayneg, also interesting replies too, some agree, some disagree.
I have never tourqed the wheel nuts before, but will be doing so from now on!
I always do them up in the 'star pattern' to evenly distribute the tension, and give them all about the same force of tightening with a breaker bar.
Interesting that I have never seen a tyre shop do up the wheel nuts with anything other than a rattle gun, I'm guessing they must have the guns set to a ballpark tension for all vehicles.
Looks like I'm up for a new set of rotors once again, hope tourqing the wheel nuts sorts the problem out.
Thanks for all the replies.
Cheers, Pete.
most tyre services that I have been to these days use a torque wrench

[mtb_gary]

I've never used a torque wrench on the wheel nuts before. I also do them up in a progressive star pattern, initially with the wheel off the ground then again with the wheel lowered from the jack.

Personally, I cannot imagine a torque wrench would ordinarily be required, if it was every car should be supplied with one and not just a wheel brace?

Gary

[p38arover]

Dont know why you have this issue however I have recently fitted all 4 new rotors to my car. Got them from ebay Oz a business seller in Qld. just over $200 the lot for genuine Brembo rotors and a free set of rear pads thrown in.

Heres a link for the fronts both for A$97 shipped,
Pair Front Brembo Disc Brake Rotor Range Rover II 4 0L 4 6L 2 5L TD 1995 01 | eBay (http://www.ebay.com.au/itm/PAIR-FRONT-BREMBO-DISC-BRAKE-ROTOR-RANGE-ROVER-II-4-0L-4-6L-2-5L-TD-1995-01-/161164920221?pt=AU_Car_Parts_Accessories&hash=item25862d859d)

Thanks Wayne, just ordered a set of fronts. Maybe I should have ordered rears, too. Do you think they are genuine Brembo?

[TheTree]

Hi

Being a little obsessive about torque settings, I generally use one where LR give the specs, and wheel nuts is one of those.

Warping is also caused by hard braking which heats up the disc to red hot, and then stopping without letting the discs cool by continuing to drive.

Steve

[wayneg]

Thanks Wayne, just ordered a set of fronts. Maybe I should have ordered rears, too. Do you think they are genuine Brembo?

All I can say is they were advertised as Brembo, came in a Brembo box.

[chopper]

Hi

Being a little obsessive about torque settings, I generally use one where LR give the specs, and wheel nuts is one of those.

Warping is also caused by hard braking which heats up the disc to red hot, and then stopping without letting the discs cool by continuing to drive.

Steve

Also after a hot/hard stopping its not good to keep the pads applied to the discs as the pad can "cook" to the disc causing a tattooed image of the pad on the disc which results in an uneven thickness to the disc which then builds up with added pad deposit thus compounding the problem which you feel as a shudder , so not actually warped at all ( in this case )
I would imagine that one cause of warping could be rapid cooling as in a water dipping .

[benji]

If the disc was very hot and the brakes applied for a few minutes, could the disc cool unevenly; just like stopping a hot disc in hub depth water.

[chopper]

If the disc was very hot and the brakes applied for a few minutes, could the disc cool unevenly; just like stopping a hot disc in hub depth water.

Sounds plausible. however the pads would also be hot, so would the pads be keeping that part of the disc hot or allowing that part of the disc to dissipate its heat before the rest of the disc. The disc half in water is easy to see.

[benji]

I imagine the pads would keep the disc hot.

[TheTree]

Hi

That article seems to suggest it is a layer of the material from the pad which gets stuck.

When I put my new front discs on, I had to bed them in. This is one article

How to bed in your new brakes for street/urban driving - EBC Brakes (http://ebcbrakes.com/articles/how-to-bed-in-your-new-brakes-for-streeturban-driving-2/)

Steve

[rangieman]

Thanks Wayne, just ordered a set of fronts. Maybe I should have ordered rears, too. Do you think they are genuine Brembo?

Ill guarantee you genuine Brembo rotors made in china ;)
Your hard pressed to find any brand rotors that are not made in China:angel:

[chopper]

[QUOTE=SteveFarmer;2145901]Hi

That article seems to suggest it is a layer of the material from the pad which gets stuck.


I think that is what I was saying, I was certainly thinking it.

"pads applied to the discs as the pad can "cook" to the disc causing a tattooed image of the pad on the disc which results in an uneven thickness to the disc which then builds up "


As for the bed in technique , who does that ? This would apply to a brand new car also . Imagine the dealer selling a car to you explaining all that, he'd scare you off and you'd finish up across the road buying a Jeep. Not.

[Keithy P38]

I bed my brakes in when they were replaced. It prolongs their life and prevents the uneven wear patterns caused by hard braking. The first thirty stops are the most important - you don't want to get them too warm.

[wayneg]

Ill guarantee you genuine Brembo rotors made in china ;)
Your hard pressed to find any brand rotors that are not made in China:angel:


I could not car less where they are made as long as they give good service and are cheap. No doubt the ore came from Oz to make the steel. From what I read all Brembo Rotors have been made in China since 2009

[goanna_shire]

A good idea if you have an auto is to knock it into neutral at the lights so you can take your foot off the anchors when stopped. Also your slides in your caliper may be getting stuck wearing your disc unevenly and putting pressure on only one side.

Cheers,
Brian

[TheTree]

[QUOTE=SteveFarmer;2145901]Hi

That article seems to suggest it is a layer of the material from the pad which gets stuck.


I think that is what I was saying, I was certainly thinking it.

"pads applied to the discs as the pad can "cook" to the disc causing a tattooed image of the pad on the disc which results in an uneven thickness to the disc which then builds up "


As for the bed in technique , who does that ? This would apply to a brand new car also . Imagine the dealer selling a car to you explaining all that, he'd scare you off and you'd finish up across the road buying a Jeep. Not.

I imagine the manufacturers do this during the build, there are many references to doing this bed in procedure

Steve