Braking issues

[Docktour Z]

When I am above 70 or so it sounds and feels like the brakes are shuddering and there is a vibrating noise. I just lowered the car and have not had the alignment done since I am putting in GT500 strut mounts this weekend. The car is still under warranty but it doesn't happen at speeds lower than that. Anyone have any ideas? It is like a grumbling with a mild vibration.

 

[JeremyH]

GET IT ALIGNED... report back if the problem is still there.

 

[Docktour Z]

You seem to be the man who answers all my questions! GT500 strut mounts on today alignment tomorrow..THANKS!

 

[JeremyH]

LOL, sounds like a plan, make sure the sway bar endlinks where they bolt to the struts are nice and tight.

 

[Vapour Trails]

I have my doubts it's an alignment issue, sounds more like a rotor issue.

Many drivers confuse rotor warping, or warped rotors, with a condition called DTV (disc thickness variation). DTV occurs when a vehicle brakes are serviced and the brake rotor has runout in excess of 0.1mm or 0.004". This runout causes the pads to contact the rotor when the vehicle is being driven "off brake" and after 3-4000 miles, a thin spot develops on the rotor. The rotor runout itself does not actually cause a vibration. It is the effect of the thickness variation of the brake disc or brake rotor under braking that causes pulsation. Even small thickness variations such as 0.01mm will exhibit itself as pulsation. A warped rotor is a very rare occurrence and in 30 years in business, we have seen no genuine cases of warped brake rotors.
The general guideline is that if the vibration happens immediately after install, there is a quite severe runout problem that needs looking into. Brake discs or rotors should be mounted on flat smooth rust and dirt free hub flanges without the use of coppaslip which includes small particles which have the same effect as dirt. Remember that even a small particle of 0.001" under the rotor surface can cause a deviation of 0.005-0.010" at the
pad contact point.
If the vibration happens after 3-4000 miles, this is a clear indication that DTV has occurred which is not a warranty condition. The only solution for this is to remove the brake rotor, have it turned by a machine shop, or replace it with a new rotor

Are you feeling this vibration when you are on the brakes or all the time? When you put your wheels back on, did you make sure you tigthened the bolts in a star pattern to the same torque value?

 

[Docktour Z]

I have my doubts it's an alignment issue, sounds more like a rotor issue.

Are you feeling this vibration when you are on the brakes or all the time? When you put your wheels back on, did you make sure you tigthened the bolts in a star pattern to the same torque value?

It is more of an issue at higher speeds, it's happened at 60mph before but is consistent above 80mph. I have a feeling the rotors are warped, is that something that is covered under the warranty? I do not think a "wear-able" part is though. Yeah, 5 star pattern...

 

[08gt4u]

i was having that same problem for a couple of weeks and it was caused by a wrong pinnion angle and a out of valance rear tire.my vibrations and shakes were at 95 mph.the alignment didnt resolve anything and since i had valance my tires the month before started, i dint think anything of it.i replaced the rear brakes to find out it wasent the cause either.

 

[Docktour Z]

i was having that same problem for a couple of weeks and it was caused by a wrong pinnion angle and a out of valance rear tire.my vibrations and shakes were at 95 mph.the alignment didnt resolve anything and since i had valance my tires the month before started, i dint think anything of it.i replaced the rear brakes to find out it wasent the cause either.

I did install an Eibach Pro-Kit by myself, I am pretty proficient though. Could this be the culprit of the different pinion angle?

 

[08gt4u]

everytime you lower a car you change the pinnion angle of it.now that this is what causing it to vibrate i dont know.i had my car lower for a year on stock suspention and i never had a vibration.my problems started when i upgraded the suspention.
in your case i would first do an alignment and i would valance my tires just to be sure.if it keeps doing it then i would look at the installed if it wasent there before.

 

[TonyN]

Sounds like a warped rotors issue to me. Or just the side effect of extreme brake fade occuring. I know when I had my stock pads/rotors they were pretty much useless once they heated up (heavy braking!). They would growl pretty loud too (In a Vrrrrrr Vrrrrrr Vrrrrrr fashion). How much pad do you have remaining?

Back when I installed my Eibachs I did not get around to doing an alignment for months and didn't adjust the P/A either. Never had any sort of noises. I doubt them are your issues. You will just get some inner tire wear in the fronts from the negative camber. I still recommend you do them, I just don't think this is your noise.

 

[phatpony]

My car is lowered with the FRPP K springs and I don't have any vibrations. Pinion angle isn't the likely suspect here. Make sure your caliper bolts are installed correctly and torqued to spec. Ensure your sway bar end links are tight, check your ball joints too, if they are shot you will feel it every time you get on the brakes. First though, get the alignment done. If they do it like my local guys, they will check tha ball joints before they align it.