I recently had new Kumho Ecsta Supra 712s installed in my car (225 front & 245 rear). I also recently replaced the rotors, calipers, and pads with new "original spec" equipment. My rear ride height has been lowered using the eccentric, and I have the 5/33 brake biasing valve. Also, my suspension is the original setup.

Lately I have noticed that when I brake hard from about 35-40MPH, I get a loud chirping/squealing noise from the front tires. I'm assuming that the wheels are locking up and the tires are losing adhesion with the road. Does this sound like the correct diagnosis?

Any tips on proper braking technique to avoid this? I'm afraid of flat-spotting my tires.

 

Initiall a few things,

The tyres may need running in a few hundred miles,

also brake shims ??? did you also use any "coppa-slip" on the back of the pads.

Are you sure the pads are "OEM" for your car.

We had a bloke who had a shiite load of squeel problem it was eventually reolved as the pads were not correct, the ones he had did not have brake chims on the actuall pad, he had a 24, with the correct pads problem was solved.

also is EVERYTHING to correct torques ??
Wheel bearings ok ??? lift front of car, grasp wheels at 6 oclock and 2.45 posintion and rock it see if there is any play.

also rotate, they should trun freely, with no binding,

HTH

Adrian

 

Just to clarify, it is not the brake pads squealing. It is the ~tires~ squealing/chirping as they rub against the road.

Also, I'm up to about 1,000 miles of highway/city driving on the "new" tires.

 

Tyre ... uh, "tire" pressures?

Jim, a totally wild guess, which I'm famous for..

 

[quote]Tyre ... uh, "tire" pressures?<hr></blockquote>

Took me a awhile to figure that out but "tyre" is the UK version for tire.

 

Get on the brakes slower...

If you lose all steering control during braking...you know the tires are locked up.

 

If the pavement is rough they may be losing contact with the pavement momentarily and chirping when they reaquire traction suddenly. I've had this happen on a 'washboard" section of road.

 

I also have Kumhos 712 all around and have driven almost 9000 kilometers with them on, It took about 3000 km:s to make them grip properly, under breaking on good roads I have to push real hard for them to loos grip and have the ABS come in.

I think they are a bit soft to drive with, seems like if they loose a lot of grip when warm... But for the price I´ve paid for them I´m happy.

Remember that on Porsches the ABS allows a lot more locking than on more normal cars.

/A

 

(Humorous reply - not intended to offend)

tt9714, I have the same tires on my '87 N/A. They are very noisy. They chirp/squeel on hard braking and really make a lot of noise when I brake on the paint at the end of the intersection. I can make the tires squeel like a pig when I corner hard on and off the freeway, before any 4-wheel drift occurs.

In my opinion, you've bought 'fat-chick' tires...... they never shut up! Best remedy: wear them out quick and change to another brand, turn up the stereo, speak in a foreign language and wear lots of gold chains. <img src="graemlins/icon501.gif" border="0" alt="[icon501]" />