brake pad throw away spec?

[NY94J30]

Anyone know the throw away spec on J30 brake pads front and rear?

rotors?

[Jeff Williams]

The dealership told me 2MM on my I30t.

[Q45tech]

Assuming you don't care about the temperature rise of the brake fluid. The pad thickness is the only insulator.

http://www.delphi.com/pdf/sae/1999-01-0483.PDF

As long as you have new dry [not wet moisture absorbed] brake fluid the 2mm change point should be ok but 90% of the cars on the road don't have brake fluid that is suitable to not boil under extreme conditions with very worn pads.

Brake pads are so cheap compared to not having good brakes, I usually change mine early at 4-3.5-3.0 mm.........vs say 9mm new.

[NY94J30]

I have 3.175 front and 6.35 rear. I am going to change the brake fluid over Thanksgiving, and turn the rotors.

Is there any reason to choose DOT 3/4 (I know Fred has recommended the Valvoline SynPower 3/4) rather than DOT 5.1?

[IvoryJ30t]

unless 5.1 is very different from 5, thats a big no. DOT 5 brake fluid has a silicone base which, although it doesnt absorb moisture, it will harm the seals in your brake system. [calipers, master cylinder]

im not sure if 5.1 is compatible, but 5 is definately not a choice.

[IvoryJ30t]

personally, ive used Castrol GT-LMA fluid in every car i have ever owned.

[Q45tech]

Kind of a price vs wet boiling point math function.

Dry boiling point is only good [measure] if you flush your fluid every month. Unless you live where it doesn't rain.

Fluid boiling is more common than the progressive decline in pad friction coefficient above 600F, unless you are making a half dozen 90 to zero stops in 10 minutes.

I use the Valvoline because every store has it and it's cheap to change twice a year and works well enough for me.

[NY94J30]

Dennis,

So your verdict is the extra 20 or so degrees F you can get out of the 5.1 isnt necessarily worth the extra money so long as the fluid is changed regularly?

[maxnix]

Look at the data in previous posts. Dry fluid is consisitently superior to wet fluid regardless fo the brand.

[NY94J30]

Brian,

I'm not following your comment - moisture is inevitably introduced into the system, so the benefits of dry fluid are moot relatively soon after changing the fluid.

The difference in wet boiling points is lower, I assume making the differences b/w 3/4 and 5.1 less substantial. Correct me if I'm wrong.