Morning all, 

 

I was going to ask some advice and get your thoughts. 

 

I have a 2013 TSI VRS DSG, and I've noticed some shuddering whilst braking. I thought at first it may have been the box changing down whilst braking but I feel something is wrong, possibly warped discs? 

 

Yesterday whilst braking from around 70, heavy braking, I get shuddering from the brake pedal, and through the steering wheel, it feels like the whole car shudders. I don't notice it as much whilst light braking. 

 

Do warped discs still happen now days? What I'm thinking is, with the dsg is it possible when being hard on the brakes before coming up to traffic lights for example and then you sit with the brakes on could the heat off the pads slightly warp the discs? 

 

Could i I check to see if the discs are warped somehow? What do you all think? 

 

Cheers, 

 

Stu. 

 

 

Could it have been the ABS kicking in? 

I never thought of that but I didn't see the ABS light kick in on the dash if there is one? 

 

It it didn't feel like the ABS but could this cause the car to shudder? 

Hello Stu, the ABS on my Octavia does tend to feel a little "rough" on the very few occasions I have had it cut in, and the pulsations did come through to the pedal. It felt like running over particularly harsh "judder bars"  This could be what you are experiencing. How do they feel in "normal" braking when just applying firm (but not hard) pressure to the pedal?  

Warped discs are very rare. What usually gets misdiagnosed as warped discs is a build up of pad material on the disc surface. This will give the symptoms you're describing. Do all the discs look clean and clear of any build up, or are the parts where you can see where the pads have been. 

3 hours ago, Warrior193 said:

Hello Stu, the ABS on my Octavia does tend to feel a little "rough" on the very few occasions I have had it cut in, and the pulsations did come through to the pedal. It felt like running over particularly harsh "judder bars"  This could be what you are experiencing. How do they feel in "normal" braking when just applying firm (but not hard) pressure to the pedal?  

 

Under normal braking I suppose they feel okay, only very minimal when changing from like 2nd to 1st upon slow speed can you feel some judder but I assume this is the box doing the engine braking part if that makes sense? 

 

2 hours ago, dale1uk said:

Warped discs are very rare. What usually gets misdiagnosed as warped discs is a build up of pad material on the disc surface. This will give the symptoms you're describing. Do all the discs look clean and clear of any build up, or are the parts where you can see where the pads have been. 

 

The 2 front discs look ok to me, there are some light lines of black marks on the front discs. 

 

1 of the rear discs has scoring on the discs. I'll try and get some pictures of the discs asap and upload. 

 

I thought warped discs are rare that's why I was wondering what it could be. 

The abs light doesn't flash when the abs is active and at that speed unless you planted your foot to the boards on the brake thus applying excessive pressure then it's unlikely the abs would have cause to activate.

 

from what you're describing it sounds like warped discs. 

1 hour ago, James@Pentagon_Seat said:

The abs light doesn't flash when the abs is active and at that speed unless you planted your foot to the boards on the brake thus applying excessive pressure then it's unlikely the abs would have cause to activate.

 

from what you're describing it sounds like warped discs. 

 

My foot wasn't planted on the brakes, just more pressure than normal. 

 

Do automatics suffer more from warped discs due to sitting with the brakes on more at lights etc? 

Not really, no.

 

warped discs are quite rare but they do occur.

Hi,

To check for warped discs you need to use a DTI and a Magnetic stand.

 

 

If it needs done it needs done, I'll try organise to get the discs checked and see if they need replaced. 

 

I would rather not replace them with OEM, anyone got any recommendations on better discs and pads? 

 

Thanks for all the input guys. 

Why not with originals?

8 hours ago, dale1uk said:

Warped discs are very rare. What usually gets misdiagnosed as warped discs is a build up of pad material on the disc surface. This will give the symptoms you're describing. Do all the discs look clean and clear of any build up, or are the parts where you can see where the pads have been. 

 

This^^^

 

Here's a good article on the warped disc myth:

 

http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths

We see "warped" discs quite frequently up here on all sorts of cars. The salt air up here causes brake pads to start sticking quite quickly and so causing heat to build up more quickly in the discs.

 

If you feel the pumping through the brake pedal and the steering wheel, it'll be the fronts and if you feel it through the pedal and sometimes your backside, it'll be the rears.

Edited 15 April, 20179 yr by HeavyMetalRich

Warped disc will vibrate on any braking, not just heavy one. ABS shouldn't be felt on steering wheel, or at least not severe, even on uneven surface.

 

What is worth to be checked is if rim is bent, or tire has failure on the sidewall. Do you recall hitting a hole or something? This is the thing I would check first.

Edited 15 April, 20179 yr by nidza

12 hours ago, James@Pentagon_Seat said:

Why not with originals?

 

Depends what you term as "originals". If you look at the standard disks that come on the car and aftermarket 'standard' disks from the likes of ATE or Brembo the difference in quality is visible especially over time. We are not talking drilled/slotted performance disks here just standard ones from the better manufacturers. Often the price difference is not that great from the factory option either.

 

19 hours ago, dale1uk said:

Warped discs are very rare.  

 

10 hours ago, Ray Luxury-Yacht said:

the warped disc myth:

 

Warped discs do happen. Even disc manufacturers have advice on avoiding it especially when new, like HERE

 

Easiest way to see is a steel straight-edge across the face of the disc. A warped disc, however, is normally felt more under light braking, as the pad is just touching the disc.

 

Often you can straighten a mildly warped disc by simply putting a bit of heat back in it and letting it cool slowly like the Brembo schedule linked to above.

 

Putting a lot of heat in the discs and then sitting hard on the brakes at lights etc is a good way to warp them. I find disc-warping follows the driver not the vehicle if you see what I mean.

 

Pad material on the disc is normally easily seen, whereas warped discs can look new. If it is ABS kicking in it it feels different to bad discs and obviously won't be felt on light braking. Worn, hard-compound, tyres on a wet greasy road can provoke ABS and the vRS single-pot TRW calipers on the 340mm discs are naturally a bit 'grabby' which does not help that particular situation either.

The OEM pads and brakes are made by TRW (on the VRS and FR that I own anyway)... not exactly bottom of the range in terms of manufacturers of braking components. 

 

As per my other post this morning on rear brakes, if correctly maintained (i.e. Sufficiently lubricated) the OEM stuff is fine, especially compared to the 'standard' Brembo / ATE stuff.

Edited 16 April, 20179 yr by Black_Sheep

1 hour ago, flybynite said:

 

Depends what you term as "originals". If you look at the standard disks that come on the car and aftermarket 'standard' disks from the likes of ATE or Brembo the difference in quality is visible especially over time. We are not talking drilled/slotted performance disks here just standard ones from the better manufacturers. Often the price difference is not that great from the factory option either.

 

 

 

Warped discs do happen. Even disc manufacturers have advice on avoiding it especially when new, like HERE

 

Easiest way to see is a steel straight-edge across the face of the disc. A warped disc, however, is normally felt more under light braking, as the pad is just touching the disc.

 

Often you can straighten a mildly warped disc by simply putting a bit of heat back in it and letting it cool slowly like the Brembo schedule linked to above.

 

Putting a lot of heat in the discs and then sitting hard on the brakes at lights etc is a good way to warp them. I find disc-warping follows the driver not the vehicle if you see what I mean.

 

Pad material on the disc is normally easily seen, whereas warped discs can look new. If it is ABS kicking in it it feels different to bad discs and obviously won't be felt on light braking. Worn, hard-compound, tyres on a wet greasy road can provoke ABS and the vRS single-pot TRW calipers on the 340mm discs are naturally a bit 'grabby' which does not help that particular situation either.

 

The Brembo link you posted doesn't once mention warping of a disc, infact it states the reason to bed them in correctly is to avoid uneven material build op on the disc resulting in the vibrations. 

 

No mention of warping:

"It is very important to follow proper brake bedding procedure following installation. This is necessary not only for optimum performance of the system, but also to avoid onset of judder (vibration felt through brake and steering)."

 

and again, no mention of warping:

 

"With too much heat or pedal pressure, this plating can be deposited unevenly on the disc, and impregnated into the pad, further increasing the likelihood of judder development"

 

It takes serious amounts of heat to actually warp a disc, far more than should ever get into a disc on the roads. 

 

Don't confuse warping with material build up or hub run-out, both if which are the reason for the vast majority of people's brake shudder. 

 

Measuring a disc with a DTI or any other means may show that the disc surface is uneven, but it won't have warped from a heavy right foot on the brakes, but most likely the run-out is out of spec. Getting  the discs skimmed on the car will rectify this. 

 

More info on hub run-out:

 

• Once the disc has been installed, use a DTI (Dial Test Indicator), fixed to the suspension strut, in order to measure the run-out of the disc on a braking surface near to the outer edge. The runout value after one complete turn of the wheel must not exceed 0.1 mm. If the value is greater, change the position of the disc in relation to the wheel hub (if the tightening hole allows) or install as above the second disc from the pack. If the disc is held in place by means of a single bolt, attach it to the wheel hub with two more bolts (using the wheel nuts with spacers corresponding to the thickness of the rims) in order to simulate the rotation conditions once the wheel has been fitted. Measurement of disc run-out is an extremely important operation: if run-out is excessive, in due course after a few thousand kilometres the disc may be affected by abnormal wear when the vehicle is not being braked (due to partial contact with the brake pads) and during braking there will be vibrations. The maximum tolerance for run-out once the disc has been installed as indicated by Brembo has been determined on the basis of experience. Certain manufacturers may indicate slightly different values. In such cases the original values should be followed.

 

Again, this is not a "warped" disc and no amount of gentle heating will fix it.

 

 

 

 

 

 

 

 

Edited 16 April, 20179 yr by dale1uk

Heavy braking from 70mph!!!  Perhaps a change in driving style and better observation of what is happening ahead would help?  I am by no means a slow driver and can't remember the last time that 'heavy' braking was necessary; the ABS has cut in only on very rare occasions in 30K miles of driving the car and they were all on slippery surfaces.

49 minutes ago, philbes said:

Heavy braking from 70mph!!!  Perhaps a change in driving style and better observation of what is happening ahead would help?  I am by no means a slow driver and can't remember the last time that 'heavy' braking was necessary; the ABS has cut in only on very rare occasions in 30K miles of driving the car and they were all on slippery surfaces.

 

It was for the purpose of testing when the juddering is happening coming off a slip road from the motorway with nothing else around. I'm sure it was not the ABS. 

 

After reading all all the provided links, it's possible it could be build up on the discs. I bought the car second hand so I have no idea how the braking has been treated over the years. 

 

If they need changed they need changed - no biggie but I wanted advice beforehand from members on here that are more experienced than me and knowledgeable. 

 

Thanks people. 

53 minutes ago, dale1uk said:

Don't confuse warping with material build up or hub run-out, both if which are the reason for the vast majority of people's brake shudder. 

 

I have had more warped discs on my bench than pad deposits, that is just my experience. Only way to see this is a straight edge across a clean disc as said above. They also feel different when you brake. Granted it is unlikely on a 340mm vRS disk on normal road use because of the heat capacity of that amount of spinning metal, but it happens.

 

A DTI will not confirm warping, it can indicate lots of things, completely agree.

 

Runout is another common problem. Lots of causes for that, agree there too.

 

1 hour ago, Black_Sheep said:

if correctly maintained (i.e. Sufficiently lubricated) the OEM stuff is fine

 

Nothing wrong with TRW components, just there are better out there. It is a valid reason not to not to replace factory components like-for-like as was asked above. Some discs tend to have better coatings on the exposed parts than others and last a bit longer without corroding especially in harsher conditions.

 

Cleaned sliders and runners are vital especially on single-pot calipers - can't be said enough. Surprising how many come out of disc and/or pad changes with these untouched.

Usually pad deposits..get this loads due to salt on roads etc. up here..

 

...however you can get sticking of the caliper on the sliders....more likely to be felt without braking, but another item to check..

 

Again though our fronts are like my old Fabia rear, sliders are protected by accordion style boots, so no exposed pins...so just check mating faces of pads/carriers/calipers

Edited 17 April, 20179 yr by fabdavrav

On 4/15/2017 at 21:45, Ray Luxury-Yacht said:

 

This^^^

 

Here's a good article on the warped disc myth:

 

http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths

Now that is a very good, informative article on brake discs, thanks for posting the link Ray. The pad bedding-in process described is pretty much identical to what I was told when I was running DS11 / VG95s on my Cooper S back in the 70s.  

Ooh BMC. Don't get me started. Warped brake drums anyone?

The drums on the 'S' were never a problem for me, maybe the VG95s helped with that - they didn't do much of the braking anyway (apart, of course, from the HB) as the booster was plumbed to send all the pressure to the 8.5 inch front discs and the rear drums only got normal pedal pressure. Surprisingly, this balance worked very well, especially with the rear pressure limiter removed.