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Discussion Starter · #1 ·
The situation: Aggressive braking is activating the ABS WAAAAAY too soon. Like, can barely outbrake my brother's Kia Optima too soon.

What I did: Just got the car out of the shop... the rear pads were replaced, and rotors turned... and new rear tires (Yoko A048s) put on the car.

Front pads and rotors were done last month, maybe ~1000 miles difference in wear. Ferodo pads in front, Porterfield RS4 in the rear. Girodisc rotors.

Front tires still have >50% tread on them, so I left them alone (Yoko A048s)

My thoughts: Did they tweak an ABS sensor? Or is the mismatch in pad compounds potentially responsible? Did they put something together wrong? Leave a giant glob of grease on the rotor?

My Other Problem: I am 3000 miles from the car, and getting this information from my brother who I trust implicitly, but still... I am not there to poke at it first hand.

Ideas? Comments? Much Appreciated!

-Matt
 

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He's on fire!
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Tires not up to temp? Cold tires = less grip = abs comes on sooner. Also, I've yet to see a new set of a048 but typically *new* tires are slicker until you scrub off the outermost layer. Again, less grip = abs comes on sooner.
 

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No, grease on rotor would have the opposite effect.

I can't see why bleeding would be helpful.

Difference in compounds could easily be the issue. Which end locks up first?

All brake pads need to be broken in properly. Do you know if this was done?

Some pads, like Carbon Lorraine (sp?) have too much bite when 1st installed, but that goes away with use.


As above, new or cold tires have less grip.
 

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www.theapexinn.com
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matt: If you had it done at AutoEurope...just call them .....they stand behind their work and if it's not right, they'll fix it !
 

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Discussion Starter · #6 ·
Yeah it was done at Auto Europe, and its back there now... they have been great to me every time so far, I guess this will be a test of that!

Update: They pulled it back in and tried to talk to the ABS/Traction Control module(s) - they said they couldnt get the car to talk to them, and they needed to pull the front clam!?? -eek-

I had zero ABS issues before I took it in for a routine pad change... not sure what else to think other than 'something' happened when they worked on it. :confused:

-Matt
 

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Brand new brakes and tires on the rear and used brakes and tires on the front? Did anyone burnish the rear brakes and tires at all? If not you will have issues at high decel until the rear brake friction comes up and the tires break in.
BTW, new kia optimas stop pretty good, I don't know how the comparison was made but...

Sent from my MB860 using AutoGuide.Com Free App
 

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pretty sure the Ferodo fronts will have a lot more initial bite than the Porterfield R4s rear pads... I have the R4s as my street pads, and they feel very slippery initially compared to my Ferodo DS2500 or other race pads.

I could easily see that cause the ABS system to freak out a bit.
 

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Discussion Starter · #9 ·
Another Update: So Auto Europe has been fantastic to work with... when the owner of the place personally takes your car out to test drive it, even after they closed for the day? Yeah... thats customer service. Oh, and the clam removal was a miscommunication caused by 3000 miles, 3 hour time difference, and poor reading comprehension. :p

What they did: [short version] Swapped the old brake pads back in, took it back out... was better, but still behaving poorly. At this point the only changes to the car are the new rear tires, and the fact that the rear rotors were turned. So its either the new tires, or ... everyone is baffled. Both test drivers seem to think the fronts are locking up/breaking loose first, which would seem to match up with what Vulcan is saying about compounds... but then why would it still behave badly when they went back to the pads that just came off? Or could it be the rear tires are actually still too slick, and sending the bias to the front? [long version] there was rechecking of bolts, cleaning everything that moved, inspecting everything... they spent some time on this. But at the end of the day agreed its drivable, but its not "right" ... and I want to go to Grattan with it in a few weeks. ;(

I fly home tomorrow night, but I think they're going to be back at it in the morning... crossing my fingers.

And my brother is my eyes and ears back in MI, he drives the KIA and compared it back to back on the same street with my car... Not precisely scientific, but close enough for my purposes at this point. :)
 

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Until you get the rear brakes burnished to the rotor and they spend some time at temperature the rear output will be low. Sounds like you have had a bit of driving on the car so the rear tires are probably cleaned up but I usually like at least 60 miles on a set of tires before I do any type of stopping distance. The mold release agent on tires van be pretty slick.

Sent from my MB860 using AutoGuide.Com Free App
 

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After new pads (Yellow Stuf) and cutting rotors it takes a week for my brakes to be maximum. My guess is the rear is more aggressive now and the puter don't like it. Be patient, bed the new pads then see what happens.
 
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