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Are 'warped discs" a myth


Tango
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  • 4 years later...

Im sorry to resurrect this thread as i know its old....

 

My friend is tracking his 300zx. He has done a brake upgrade to the 350z front brake calliper and disc's.

 

 

 

He is adamant that he is having warped discs but im saying its due to bad discs or pads.

 

These are his symptoms.

During normal driving the brakes are fine, no judder or vibrations... After about 20 min on the track and his brakes are getting hot.. The whole car shudders under any type of braking (light or hard).

The shudder feels like the whole car should fall apart and is very violent.

 

If he lets the brakes cool then pulls in to the pits, after about 30 min the brakes are back to normal. Then after some heat gets in to then they vibrate like mad again.

 

We have checked:

No debris between hub and disc face

No cracks in the disc

Pads are not cracked or broken

 

 

We have not checked for overall flatness of the hub but its on the list to do.. Just need to locate a DTM first.

 

Any suggestions please?

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Reads like a sized calliper to me hence the heat cycle..... I would be tempted to check how hot the wheels are when the vibration starts, obviously if one is hotter than it's partner then there's the problem.

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Calipers are not sticky. They are free and almost new. They where removed from the original car a few hundred miles from new as the 350z owner put a bbk on it.

 

The 300zx has had a diet somewhat but obviously is still a bit of a fatty. It has had:

Most interior removed, new bucket seats, ac removed, fan replaced to its an electric fan not the original fan driven off the crank.

 

The plan is to put ducting where the original SMIC's where and have piping run through to the brakes for vents to help cooling.

 

I will find out what pads are being used but afaik the discs are brembo blanks.

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Update... Hes using brembo pads and 'high quality' blank discs.

I am trying to get him to try ds2500's on the car.

 

He did another track day and this time it was happening after 3 laps.

 

To me i think he needs to bin both pads and discs, and get new decent pads and brembo discs

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  • 1 year later...

I had brake vibration on a ML63 AMG that had had new Genuine discs all round, front pads Tarox rear Pagid.

I run a dial gage on each disc and on the outer rim no runout but one, N/S front was off the clock.

I pulled all the discs and that front had a huge rust scab on the hub face.

It looked like it had been a problem the last owner had tried to over come with cranking the wheel nuts up so tight I needed a 1M bar to undo the bolts!

The wheel had some hub distortion  on the rear face!

All cleaned up and better but still had a vibration even when the dial gage read true on the outer face.

Time to get it on a MAD disc cutter as the pads had worn the disc uneven.

Results are 100% and just a small amount of each front inside and out where cut with the MAD cutter.

Brakes are now silky smooth.

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