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Shaking under Braking


Bendrews

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Hi all,

 

ive had a quick search around and cant seem to find anything on this,

 

it seems that when im braking the car shakes as if there is a lump on the pads, :headhurt:

i cant physically see anything and have just bought the car off a dealership who put the car through the workshop the other day,

has anyone else had this problem or know of any solutions?

 

help is much appreicated,

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Alot of Zeds (mine included) have suffered from this. In my case I think it was caused by brake runout although alot of people that have EBC rotors (again me) have noted this.

 

If you bought it from a dealership I would take it back to them sharpish and have them measure the DTV (disc thickness variation). May be that you need them skimmed or replaced so better to talk with the person you bought from quickly before they can claim that it's normal, post purchase wear and tear.

 

If it was a private sale I fear you may end up having to replace the discs and pads out of your own pocket.

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As what James B says. :thumbs:

 

Take it straight back to the dealership immediately and leave it with them until it is fixed properly.

 

It should not have left the dealership with a severe brake shudder.

 

Did you not test drive the car prior to purchase.?

 

Alex :)

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Cheers for the quick responses everyone :thumbs:

 

ive booked in to the garage for friday, they have said there is newish discs on it but we will see .... if they cant figure it out, the car is still under warranty :thumbs: so they will replace etc im guessing...

 

cheers for the link for bedding in Magnet ! it makes for good reading :lol:

 

Alex i did test drive the car but i didnt push it so it wasnt as noticable at the time and the excitment of actually driving was ALOT :teeth:

 

+1 Definaterly take it back mate. Should hopefully get it sorted for the meet on Sunday then!! :lol:

 

BTW, were you driving through the underpass towards the tunnel at about 8.30am today?

 

yer hopefully its a simple fix for them! Yer i was driving through there did u see me lol?...

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alright guys quick update on this:

 

took the car in today and they came back and said that i will need new brake discs and pads! totals out at £790 ish but they will be covering this cost!

 

right now for the reasoning for new pads is that the old ones hadnt been used properly in a while and had become rusty.... making spots on the dics where caused the shuddering effect when braking....

apparently they had the discs smoothed down before i picked the car up to get rid of the rusty bits but doesnt seemed to of worked...

 

so i get new discs and pads.... :thumbs:

i know some of you will say get uprated brakes but because its under warranty i can only get the standard ones i believe... :shrug:

 

does anybody know what discs the standard car has it an 07 With the budlge in the bonnet i believe its engine is a VQ35HR 309bhp

 

any help is great :)

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If it is a Nissan garage and they fit genuine Nissan replacement parts then they should be fitting genuine Nissan parts which in this case will be Brembo.

However, most Nissan dealerships when dealing with sales cars will fit cheap aftermarket brake components.

I would make them aware that you will not accept anything less than OEM Genuine rotors and pads. :thumbs:

 

Alex. :)

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  • 2 weeks later...

You will honestly not get them offering better than Brembo (which is hard to begin with). NMy advice is same as ZMANALEX and only accept OEM Brembo if it needs changing.

 

I promise they will try and palm some shite aftermarket off on you. Don't be a fool and let them!

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£790 :scare:

 

at that price it must be OEM as Alex has pointed out otherwise you'd be far better off installing uprated aftermarket pads and discs. You gould have DBA4600 discs and DBS2500 Ferodo pads for far less than what the garage is charging

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Hi All,

just an update,

 

i got the car back, they gave me a TOYota Aygo as a Loan car :thumbdown: Offically the worst car ever it feels like a van!

 

anyway, the garage said it wud be ready within the day so i rang up at the end of the day and it wasnt done becuase the "specialist" wanted to redo the brakes :dry: , so had to wait 2 days

by redo the brakes they mean skim them in some machine that has a perfect blade!

 

first things first , i was told they were warped discs (my interpretation of this is BROKEN discs, please correct me if im wrong)

so how is a machine guna fix these warped discs, apparently it will straighten them and take off the top layer of the discs so they are fresh as such?!??

 

as i was told i was getting new brakes do i take it back and say they are still not right (bare in mind they sold me they car with faulty brakes, this im guessing is not good for them if the authorities find out) or do i accept the brakes as they are... they seem to be ok but i havent tryed hard braking as i do not want to glaze them

 

they done all 4 brakes aswell

all advice is great

 

Cheers

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Do you have it in writing that they were going to replace the discs or did they just say they would fix them? If you have it in writing and they havent changed them I'd demand they do. If you dont, then you'll have to ask nicely to get them replaced as if skimming the disc (their magic machine) can fix the disc if it only had DTV or pad build up on the disc.

 

Read this and go back informed with this info from StopTech :thumbs:

 

http://www.stoptech.com/tech_info/wp_wa ... disk.shtml

 

Myth # 1 – BRAKE JUDDER AND VIBRATION IS CAUSED BY DISCS THAT HAVE BEEN WARPED FROM EXESSIVE HEAT.

 

The term "warped brake disc" has been in common use in motor racing for decades. When a driver reports a vibration under hard braking, inexperienced crews, after checking for (and not finding) cracks often attribute the vibration to "warped discs". They then measure the disc thickness in various places, find significant variation and the diagnosis is cast in stone.

 

When disc brakes for high performance cars arrived on the scene we began to hear of "warped brake discs" on road going cars, with the same analyses and diagnoses. Typically, the discs are resurfaced to cure the problem and, equally typically, after a relatively short time the roughness or vibration comes back. Brake roughness has caused a significant number of cars to be bought back by their manufacturers under the "lemon laws". This has been going on for decades now - and, like most things that we have cast in stone, the diagnoses are wrong.

 

With one qualifier, presuming that the hub and wheel flange are flat and in good condition and that the wheel bolts or hat mounting hardware is in good condition, installed correctly and tightened uniformly and in the correct order to the recommended torque specification, in more than 40 years of professional racing, including the Shelby/Ford GT 40s – one of the most intense brake development program in history - I have never seen a warped brake disc. I have seen lots of cracked discs, (FIGURE 1) discs that had turned into shallow cones at operating temperature because they were mounted rigidly to their attachment bells or top hats, (FIGURE 2) a few where the friction surface had collapsed in the area between straight radial interior vanes, (FIGURE 3) and an untold number of discs with pad material unevenly deposited on the friction surfaces - sometimes visible and more often not. (FIGURE 4)

 

In fact every case of "warped brake disc" that I have investigated, whether on a racing car or a street car, has turned out to be friction pad material transferred unevenly to the surface of the disc. This uneven deposition results in thickness variation (TV) or run-out due to hot spotting that occurred at elevated temperatures.

 

In order to understand what is happening here, we will briefly investigate the nature of the stopping power of the disc brake system.

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Do you have it in writing that they were going to replace the discs or did they just say they would fix them? If you have it in writing and they havent changed them I'd demand they do. If you dont, then you'll have to ask nicely to get them replaced as if skimming the disc (their magic machine) can fix the disc if it only had DTV or pad build up on the disc.

 

 

im afraid they only told me verbally when i took it down there :rant: will have to get it in writing next time :bang:

 

ive being using the car as little as possible this week but the brakes seem to be just fine at the moment .. i havent really pushed to hard on them yet tho...

 

i have asked nicely and they said that the magic machine will fix them :dry:

 

my only worry is that the shuddering comes back, or the brakes fail to work correctly at the time i need them most.... :surrender:

 

at this point i will demand that they give me new ones :thumbs:

 

cheers for the advice Chris

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  • 3 weeks later...

If the discs are skimmed up on the car then it will fix your run out problems and the vibration will go. However, having said that be very careful skimming can hide underlying problems, such as a wheel bearing on the way out or a bent hub. I know I have a bent hub on mine, back left. After getting the hub off and measured on the CMM at work two "lobes" on the hub were 0.1mm lower than the other 3 so the disc sits wonky on the hub thus runout was about 0.4mm at the edge of the disk. Ideally you want as close to 0 runout as possible, but less than 0.07mm at the back and 0.05mm at the front is acceptable on the Brembos.

 

In my experience its not usually warped discs but has been caused by discs not being fitted correctly.

 

It is essential when changing disks to check the runout of the disk with a proper DTI and make sure run out is in spec.

 

A way to check how many of your disks are running out is drive around for a bit, stop and feel your disks. If any differ in temperature from the rest they are running out for some reason. Either warped or not fitted properly.

 

One thing to be wary of is that when they skim your disks they don't take them too near to minimum disk thickness because then they will warp due to thermal stresses and possibly crack. Additionally if skimmed near minimum thickness the temps can cause microstructure changes in the disc material causing hard spots to form which don't wear down as the rest of the disc does and then the vibration comes back.

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  • 1 month later...

Apologies for resurrecting an old thread, but...

 

My disks and pads have been on the car for a long time now, but recently have developed a distinct judder, pretty much as described by the original poster on this thread. I can't see any obvious flaws or excessive wear on the front of the disks but have not been able to check the rear faces.

 

I have a set of replacement pads ready to go on, but the ones on the car don't seem to be too far gone at this stage. Is it worth trying the bed-in procedure with the existing pads or is the general opinion that it would be better to instal the new pads first?

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