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jaga

Vibration While Braking At High Speed

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Dear Friends,

Recently my car started rattling while braking at the speed of above 80km/hr. I feel the steering and the dash board start vibratings when you paddle the brake slightly down at high speed and when you press hard it gives some rubbing noise as well.

After changing front disc pads with genuine parts from the agent it has done about 20000 km. when I told this problem to the agent they asked me to phase the discs but I persenally checked the discs and found those are smooth.

According to your experience what will be the most possible reason. Could be the inferior quality of the pads?

Thank you,

Jagath

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After changing front disc pads with genuine parts from the agent it has done about 20000 km. when I told this problem to the agent they asked me to phase the discs but I persenally checked the discs and found those are smooth.

its not the smoothness of the disks mate! chances are they are probably warped

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Dear Friends,

Recently my car started rattling while braking at the speed of above 80km/hr. I feel the steering and the dash board start vibratings when you paddle the brake slightly down at high speed and when you press hard it gives some rubbing noise as well.

After changing front disc pads with genuine parts from the agent it has done about 20000 km. when I told this problem to the agent they asked me to phase the discs but I persenally checked the discs and found those are smooth.

According to your experience what will be the most possible reason. Could be the inferior quality of the pads?

Thank you,

Jagath

Hmm.. sounds more like a warn out Caliper pins to me.. better check with a reputed Mechanic..

Edited by Ruslan

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your disks are warped. If they're still within spec. (minimum thickness hasn't been reached) you can get them cut at a machine/brake shop, or you need to replace them.

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your disks are warped. If they're still within spec. (minimum thickness hasn't been reached) you can get them cut at a machine/brake shop, or you need to replace them.

Mean Green z28 could you please elaborate on this?

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He means that the disks are no longer flat- this unevenness results in the pads not having enough area on the disks to ‘rub up’ against when trying to slow the car down.This has a sort of a slip effect which is pronounced more at higher speeds when more is demanded out of the breaks. This also causes over heating and over wear of the break related components in a car. Had the same problem. You need to remove the disks and take them to a decent lath to get them phased. Will cost you a little bit over 1k per disk

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He means that the disks are no longer flat- this unevenness results in the pads not having enough area on the disks to ‘rub up’ against when trying to slow the car down.This has a sort of a slip effect which is pronounced more at higher speeds when more is demanded out of the breaks. This also causes over heating and over wear of the break related components in a car. Had the same problem. You need to remove the disks and take them to a decent lath to get them phased. Will cost you a little bit over 1k per disk

Thanks Elvis.

Any particular reason for this to happen?

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Thanks Elvis.

Any particular reason for this to happen?

Excessive heat I'd imagine. Maybe due to rough driving- sometimes automatics tend to pulse the breaks a lot causing excessive heat- which the marterials used on the disk cannot handle which makes the disks warp. Maybe even really hard breaking as in race track situations.

Some say that even suddenly cooling hot breaks could cause them to warp- for instance when spraying water on the wheels at a car wash after doing a hard drive. :blink:

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Excessive heat I'd imagine. Maybe due to rough driving- sometimes automatics tend to pulse the breaks a lot causing excessive heat- which the marterials used on the disk cannot handle which makes the disks warp. Maybe even really hard breaking as in race track situations.

Some say that even suddenly cooling hot breaks could cause them to warp- for instance when spraying water on the wheels at a car wash after doing a hard drive. :blink:

Thanks Elvis.

I should remember to let the car cool off before washing.

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It is very clear now and thank you everybody. :)

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Warping usually happens when the disks heat up a lot more than they're usually expected to handle, and also when they're near their end of life; 'cos the disk is worn out so much that it cant handle the heat build up. Basically think of it like a potato chip. It may be nice and flat and measure the same, but is wavy and therefore makes the car shudder when you apply the brakes. Like Elvis said, it needs to be put on a lathe and checked; if the thickness of the disk is under the min. spec after they are cut (an experienced machinist could tell you that by measuring the high/low areas before they are cut), they're no good, 'cos they'll warp really quick even after a few hard stops.

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Also its advisable that when you phase the disks also phase the rear drums too and you should change the brake pads and the shoes. Don't ever put the old worn pads on the phased disk. If you have brake pads in good condition you can phase them too but most of the lathe shops don't phase the pads. You can do it your self with a piece of sand paper and an at least 1 square feet piece of glass to make sure the surface is flat.

The best place to get phased is Viskam Brothers (Pvt) Ltd which is on Bloemendhal Road behind Sugathadasa Stadium. They have all the latest machines and well trained people. Also Royal at panchikawatte. (opposite Tyre House Building).

Wiskam charges Rs 475.00 for one piece so if you want to phase 2 disks and 2 drums it will cost you Rs1900.

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Hi all,

I was initially thinking of ignoring the incorrect term "phase" used, then felt it may help to explain the correct terms which becomes self explanatory. We call this re-facing or skimming-or even grinding. Thr job involves removing a very thin layer of metal from the face of the brake disc-the contact area with the pads,to remove the high spots caused by distortion of the brake disc. The same theory applies to cylinder heads as well.

On another angle before you fit discs on to a car make sure the mounting flange is throughly cleaned and completely flat and smooth. Any un even patches here regardless of how small will cause the discs to warp(distort) after a short period of use and will ruin your new discs. If you had to use excessive force with hammer blows etc to remove the old rusted discs it may cause damage to the flange.

Maithri.

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Hi all,

I was initially thinking of ignoring the incorrect term "phase" used, then felt it may help to explain the correct terms which becomes self explanatory. We call this re-facing or skimming-or even grinding. Thr job involves removing a very thin layer of metal from the face of the brake disc-the contact area with the pads,to remove the high spots caused by distortion of the brake disc. The same theory applies to cylinder heads as well.

On another angle before you fit discs on to a car make sure the mounting flange is throughly cleaned and completely flat and smooth. Any un even patches here regardless of how small will cause the discs to warp(distort) after a short period of use and will ruin your new discs. If you had to use excessive force with hammer blows etc to remove the old rusted discs it may cause damage to the flange.

Maithri.

Huh..I used call reface as well until i saw Pila's post on this topic and thought Phase must be correct as I know Pila has got more knowledge about the cars more than me do. So I was correct then. Thanks for correcting us Maithri.

Just took my car maintenance file and checked the invoice of Viskam brothers and found it also has been printed as Reface.

(I had done to my car few months ago)

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Hi Guys,

I'm having the same problem with my FD1 when driving over 100. During the last service at the agent. I asked them to look upon to it and check wheel balancing and stuff as well. And they showed me that there is 10 degrees angle out in the front right side ( ideally it should be within 0 - 30 range. But it was 40 degrees ). They didn't tell me anything about brake pads or disks. But adviced me to replace the knuckle which costs at the agent around 43K.

I was going to do it, but then again I got to know it can be fixed from some wheel alignment shops ( by pulling the knuckle or something that I am unaware of ). Today I went to C*r *Ca*e to get an idea on that. And they said that can be done using a puller. But if the pulling range is higher, they said there is a tiny chance it might affect the shock absorber.

My concern is, does anyone have any experience with this puller mechanism? Will that add any unwanted side effects?

And also if I am to get the knuckle replaced, can you please suggest any recommendation :).

 

Thanks in advance

 

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Hi, seen warped front discs do the same .

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On 1/26/2009 at 3:13 PM, JadeyBlitzen said:

its not the smoothness of the disks mate! chances are they are probably warped

Correct. I also experienced a similar issue with rear brake drums. No alternative other than replacing the entire part.  

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