Warped Disks - again!

[COD]

Hello All,

I need your help and advice. I have a W211 E320CDi saloon 53 Reg.

My brake disks are warped, again
The disks and pads have been changed completely on two occasions. First time it was Pagid disks and pads and the second time Eicher disks and pads. Lastly, 1000 miles ago, the front disks and pads they were changed for genuine Mercedes Disks and pads. The current genuines are under warranty for another 9 weeks, however I dont want to change them when the primary cause of the warping has not been fixed.
Please can someone let me know what the possible causes could be?
I would like to present a list to the last gargage I used, so they can ensure pins, calper springs etc are changed at the same time.
This problem is spoiling a really nice car

Thanks in advance for your help

Paul

 

[Sp!ke]

Do you do track days or something?

If not, perhaps your calipers are sticking or the hub wasn't cleaned before fitting the new disks. one things for sure is that this shouldn't be happening.

Unless of course you drive an auto with two feet.

 

[davidsw]

What mileage between disk & pad changes ?

 

[davidsw]

Disks not sitting square .Pads not releasing causing overheating. calliper fault pistons or not sitting square.

 

[COD]

Thanks for your replies.

I don't do track days, although I might start In fact I might try banger racing.
I only drive with one foot in my Automatic. I drive so many miles my left leg goes to sleep!!
First set of Pagid disks warped after 2000 miles, changed at 4,000. The Eicher started to vibrate after 2000 miles, but werent as bad as the Pagid's. They were changed after about 13,000 , when I couldnt tolerate the vibration any more.
I will take the list provided to the supplying and fitting Independent I have used ( a forum sponsor) and ask them to check everything is functioning correctly.
One other question:
Could the car have been damaged in an accident and part of the suspension/braking system be permanently damaged, if so is it easy to diagnose this particular problem?

Many thanks

Paul

 

[Sp!ke]

If you explain the issue fully to any mechanic worth his salt he should be able track this issue down.

It just needs a methodical approach and probably dial gauge to make sure everything is absolutely true.

 

[John]

The starting point is to get the suspension and wheel geometry checked by a place who knows what they are doing.

Wheels in Motion in Chesham are top dollar for this if you are in the Buckinghamshire area on your travels.

 

[Sp!ke]

I wouldn't have thought warped disks is linked to poor geometry at all.

Interested in your logic on this.

 

[cb1965]

Hello All,

I need your help and advice. I have a W211 E320CDi saloon 53 Reg.

My brake disks are warped, again
The disks and pads have been changed completely on two occasions. First time it was Pagid disks and pads and the second time Eicher disks and pads. Lastly, 1000 miles ago, the front disks and pads they were changed for genuine Mercedes Disks and pads. The current genuines are under warranty for another 9 weeks, however I dont want to change them when the primary cause of the warping has not been fixed.
Please can someone let me know what the possible causes could be?
I would like to present a list to the last gargage I used, so they can ensure pins, calper springs etc are changed at the same time.
This problem is spoiling a really nice car

Thanks in advance for your help

Paul

I presume every time the disks have been changed the vibration has gone away only to return later? If so we know it's deifnitely the disks being warped that is causing the issue.

Now this may or may not be relevant, but when I used to do trackdays with my Subaru I used to do a few laps and then come off the track and wait for everything to cool down. Sometimes there was a queue to get from the pitlane to the holding area and one particular day there was queue every time and on the way home I realised my brakes were vibrating. My garage buddy took a look and asked what I had been doing and he reckoned that sitting in a queue with my foot on the hot brakes (because I was too darned lazy to put the handbrake on) meant that hotspots got created on the disks and they warped.

Now in an auto it is quite normal to sit on the brakes when you come to a stop, but I must admit I try and not do that in my SL if I have just been indulging in some heavy braking as the hot disks stay hot under the pads yet cool everywhere else and that is I believe one of the ways they can warp.

Now I have no idea how you drive your car or whather this could be an issue, but it is worth thinking about. Some cars have much better brake ventilation than others and it may just be yours isn't well ventilated and you are doing something like the above that is warping them.

If not tell me to shut up

 

[davidsw]

check temperature of front wheels after a drive , make sure they are not too hot and even. If the problem is sorted after disk and pad change , even if only for a short time , then it must be something to do with parts touched.ie wheel , brake disk or calliper.

 

[BlackC55]

I would put good money on the hubs having corrosion on them. It is a common problem if the hubs are not cleaned fully.

 

[BlackC55]

We use these on the hubs.

flap disc | eBay

 

[Sp!ke]

We use these on the hubs.

flap disc | eBay

I assume you don't use a coarse grade or you can cut back metal pretty quickly with flap disks.

 

[BlackC55]

We are very gentle with them.

 

[ItalianTuneUp]

From earlier discussion of 'gritty brakes', sounds like my discs might need a dab of one of these gizmos on them.

 

[COD]

I presume every time the disks have been changed the vibration has gone away only to return later? If so we know it's deifnitely the disks being warped that is causing the issue.

Now this may or may not be relevant, but when I used to do trackdays with my Subaru I used to do a few laps and then come off the track and wait for everything to cool down. Sometimes there was a queue to get from the pitlane to the holding area and one particular day there was queue every time and on the way home I realised my brakes were vibrating. My garage buddy took a look and asked what I had been doing and he reckoned that sitting in a queue with my foot on the hot brakes (because I was too darned lazy to put the handbrake on) meant that hotspots got created on the disks and they warped.

Now in an auto it is quite normal to sit on the brakes when you come to a stop, but I must admit I try and not do that in my SL if I have just been indulging in some heavy braking as the hot disks stay hot under the pads yet cool everywhere else and that is I believe one of the ways they can warp.

Now I have no idea how you drive your car or whather this could be an issue, but it is worth thinking about. Some cars have much better brake ventilation than others and it may just be yours isn't well ventilated and you are doing something like the above that is warping them.

If not tell me to shut up

Please don't shut up, this forum is so useful and has solved many of my cars minor problems

On my regular journey up and down the M1, to Leicester or Birmingham and on a Friday heading home. I regularly use the SBC H when I come to a stop. To be honest I am aware that if brakes get too hot they can warp, I am not really aware of occasions where I have been braking hard and then coming to a complete standstill, usually it is a gradual slow down and then stop.
Maybe this is the cause?? if so, then the car isn't suitable for my needs

I am going to contact the Indie that fitted the new disks and pads and mention all of the great advice I have been provided with on the forum
Hopefully they will listen to this advice and solve the problem. I did mention in precise detail the previous problems I was having. Fingers crossed it is solved this time, if not a change of car will be necessary, and that is not something I will do lightly.

 

[hotrodder]

Brake discs don't warp (physically distort like a buckled wheel), the judder that typically gets blamed on "warped discs" is DTV, disc thickness variation [/pedantic]. Many of the causes have already been touched on but FWIW...

If there's too much disc runout then the disc can end up being unevenly worn after a few thousand miles. Only talking about a miniscule variation in thickness before a judder can be noticed through the pedal. This is why rust deposits on the hub were mentioned (grit or burrs can have the same effect) along with a dial gauge to measure run out.

Brakes work using both abrasive and adherent friction, basically the later means that a very thin layer of pad material is transferred to the disc in use which is constantly being worn away and replaced. Uneven pad deposits can cause thickness variation too hence the usual don't sit stationary with a foot on the brake when they're 'kin hot. Especially with new discs/pads.

Metallurgical changes can also occur with the disc from either of the above scenarios... the properties of cast iron can be altered by temperature, specifically the way it's cooled from very high temps. Hot spots on the disc as a result of run out and/or uneven deposits can locally change the hardness of the disc which in turn locally alters the way it wears leading to thickness variation and judder

Pretty much all brake manufacturers have in depth stuff on thickness variation and run out on their sites for example ATE specs... http://www.ate-brakes.com/www/downl...on-parts/download/bd_praesentation_pdf_en.pdf

Car manufacturers have similar specs for hub and disc runout, dunno about newer models but for the w124 hub specs are 0.03mm axial run out at the outer flange and 0.05mm radial at the centre register. Max disc runout (installed) is typically 0.08mm but unsurprisingly varies some with disc diameter

 

[John]

I wouldn't have thought warped disks is linked to poor geometry at all.

Interested in your logic on this.

To find out if there has been any crash damage to suspension parts...