When to Change Brake Pads?

J

JimW337

New member
I run Hawk Blues in an ITB Rabbit GTI. How much pad is enough pad before leaving for a race weekend? In other words when do you change out your old pads, 50%, 25%, 10% or when the sparks start to fly?

My first race is Nashville, very fast turn 1, the Rabbit should be doing about 110 mph at the braking point. I have about 25% pad left and am trying to decide if I should put on the new Hawk Blues. When does everyone else change out pads?
 
If you have new pads. go right ahead and change them. Might as well have everything right for your upcoming race.

Funny thing about those Blues. I swap them around on the car to even out wear--even breaking up a set. Increases longevity.

Maybe not for everyone, but it is an idea.

I stop using them when they are down to about 20% of the pad material.

Cheers.
 
25% is when you should start to seriously consider changing them. Take a look at them. Are they still uniform in composition? Are there any "chunks" missing? Are they seriously cracked and ready to fall apart? While we have good wear experience with the Golfs, I have heard reports from some of our customers of pads falling apart with 50% or more left on them. Every car/driver/system may have different wear results.

We have accidentally run Blues on the A2 Golf right down to the backing plate with no problems. However this is obviously not recommended. That same practice in the VR6 car would probably result in disaster BTW.

The amount of heat going through the pad/plate and into the caliper pistons, seals, fluid, instead of through the caliper frame and into the surrounding air I would ASSUME increases as the pad get thinner.

I have also seen the pads crumble and fall apart (more expectedly) when they get below 20% , which is BAD !
This is most likely due to backing plate flex when they get thin.

Be safe, not cheap! :D
 
Our problem is that we use up some large portion of a set of Blues on the front of the Golf in a 12 or 13 hour enduro, but still have a substantial amount of pad left. I don't run enough sprint races to use them up and have to start each long race with a new pair, so the net result is that I have about 20 pounds of perfectly good pad material in boxes on the shelf in the shop!

Start the weekend withe new ones and keep track of how much they wear. That will help you gauge how many hours you'll get with your car, style, tracks, etc.

K
 
Jim, another thought......

If I recall, when the pads wore down on that car, the pedal had more travel before actually slowing the car. Made it more difficult to heel-toe. Not a feeling I liked.

I think I made it through 8-10 race weekends on one set of Blues. But most of the tracks I ran weren't that tough on brakes. It's all about momentum in those cars. Stay off the brakes and you'll go fast!! :lol:
 
The Rabbit seems to wear pads unevenly, driver side not same as passenger side, inner not same as outer and even on an individual pad one end will wear sooner than the other end. I’ve stated taking the pads and grinding them on the belt sander and measuring them to get them even. This has really made a difference in the pedal feel.

Looks like I will put in the new pads, one less thing to worry about during the race weekend.

So, that leads me to a follow-up question. When/where do you bed in your pads? At home on the street, at the track on some access roads, or on the track during a warm up session?
 
I would also put new rotors on w/ those pads. Hawk Blues are pretty aggressive to the rotors, and ATE 9.4" vented VW rotors run ~$25/ea. When I ran my car, the rotors and the pads wore at about the same rate. When it was time for new pads, it was time for new rotors. IIRC, I got most of a season (6 weekends) out of one set. That's another thing, stick w/ ATE or maybe Brembo rotors, don't go w/ the cheap Chinese ones.
 
But don't change the pads as the same times as the rotors. You want to heat up the rotors differently. I had that problem way back in 1994 when I installed new Porterfield R4's with new rotors. Followed the instructions for break in, and burned up the R4's way too fast.

You do get a longer pedal when the pads wear, so use your one judgment. I change pads now around 30% left, and haven't had to change a rotor in quite a few races. Granted I'm running the vented 9.4" rotor on my GP Wabbit, so they do disipate more heat than the solid units.
 
No real need to "bed" Blues. They are good out of the box. If you change the rotors, use them cautiously for the first couple of laps in your first session.

For the balance of the session (and thereafter) you are good to go.

In my case, it is the same story whether you put new rotors on or not.

Besides mixing the pads freely with Blues, I also will just change the worse rotor for a new one and leave the other side alone.

Bizarre but true--especially with FWD cars.
 
I am interested in the "pedal getting longer" or the pedal having more travel as the pads wear. Any ideas as to why this would happen in any car let alone the VW?
 
I am interested in the "pedal getting longer" or the pedal having more travel as the pads wear. Any ideas as to why this would happen in any car let alone the VW?
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My theory are the pads are not wearing evenly, one end of the same pad has more material than the other end. The thick end will push the piston back in the caliper and when you apply the brakes its the thin end that determins where the pedal goes hard.

So, I just even up the pads on the belt sander and measure them. Try and get them as even as possible. The first time I did this, I was amazed how it brought the pedal feel back.
 
But don't change the pads as the same times as the rotors. You want to heat up the rotors differently. I had that problem way back in 1994 when I installed new Porterfield R4's with new rotors. Followed the instructions for break in, and burned up the R4's way too fast.

You do get a longer pedal when the pads wear, so use your one judgment. I change pads now around 30% left, and haven't had to change a rotor in quite a few races. Granted I'm running the vented 9.4" rotor on my GP Wabbit, so they do disipate more heat than the solid units.
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Tim,

I've never had a problem using new pads and rotors. I was under the impression that they essentially became a 'matched set'.
 
Should be no problem running new rotors with new pads.
Just be smart and warm them up slowly so as not to thermally "shock" any components and let the 2 parts bed properly.

Also if you have uneven pad wear... Left/right is due to your left/right car weight or caliper sliders. Inner/Outer is probably your caliper sliders.

Also, for those of you who brake hard and run fast tracks with hard braking zones. Try the Hawk HT10s.
The 9012 are a club compound for cars that dont get their brakes real hot or guys who dont modulate well and need that buffer zone that the low toque pads give you. If you want to stop faster, get the HT10. They are more expensive ( I think we sell them for around $100 per set) but you get what you pay for. And yes they are available in HB189 nad HB190 shapes.

Now, if Hawk would just make the DTC60&70 in our pad shapes! :mad1:

PS - While we're on the subject... We've been very happy with the 'new' Hawk HP-Plus AX pads on the rear. HP-Plus are cheap and effective. They are enough of a race compound that they dont burn up like street pads but still allow you to generate heat in the rears so that they are effective. Unlike a full race pad on the rear which will never heat up enough on a VW to work.
 
Interesting...I seem to recall reading Hawk literature that recommended new pads gettign broken in on used rotors, then swapping for new rotors after the pads were broken in.

Which is, of course, a pain to do.
 
One way to get more even brake pad ware on a Rabbit is to use Brass Bushings on the caliper. Very simple to have a machine shop do the work. The Bushing slides in with a shoulder on one end and a snap ring on the other. Brake pads last longer and ware evenly.
 
Yeah, that would be pretty cool if we were allowed to modify the calipers. Something to consider if goin to the NASA GTS series.
 
You would not be modifying the caliper, you are just replacing the bushings with alternate material which would be allowable.
 
Thanks for opening my mind up a bit. Funny how sometimes you just can't see something until it is laid out for you.
 
minor threadjack

What are the A1 IT guys running in the back for SHOES.

I now have so much front braking, no matter what the bias setting is, that if I accidently input 1degree of steering while hard braking, the car spins like it's lift throttle oversteer in a 911.

Any source for good rear shoe material out there?
 
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