Is it a big deal to swap pads back and forth between racing and street compounds without switching rotors? Will I destroy my pads or rotors more quickly this way?

The car is a '90 325i with OE rotors, and I'll be swapping in Hawk HT-10 pads for the OE ones in the front, OE pads in the rear.

Just make sure to properly bed-in the brake pads when you switch them, and you should be good to go. Plenty of people swap out pads at the track with out problem.

I think an important thing about swapping pads is to have a similar pad compound.
At least that was what I was told by Carbotech.
Then again, maybe they were just trying to sell me more pads. :eek:

Just make sure to properly bed-in the brake pads when you switch them, and you should be good to go. Plenty of people swap out pads at the track with out problem.

Agreed.

As an aside, the idea of running an HT-10 in the front & a stock street pad in the back does not really sound sensible, however....

Seems like a lot of people do. Rear racing pads are a lot more expensive than fronts for e30s.

I am also considering a pad compound that I can use for both like HP+. Thoughts?

Have you had fade issues with the OE pads? If not you may not need HT-10's, or you may be okay with a something along the lines of the Hawk HPS or HP+. What you need is a function of the car, the driver's skills, and what track(s) you'll run.

HP+ pads work fine on the street and they'll hang in there well past the point that the OE pads will have faded out, but they do make noise unless they are quite hot.

The car has blah whatever pads on it right now from the PO. I've never had them fade on the street or at Little Talledega, but they squeek like hell and I'm sick of it. Plus my rotors are grooved and worn, so they need replacing.

The car should be pretty quick, M50/e30 with a few little mods and a 4.10 diff. I wouldn't say I'm all that fast, but the first track I'm going to is Road Atlanta, which seems pretty brake intensive.

Seems like a lot of people do. Rear racing pads are a lot more expensive than fronts for e30s.

I am also considering a pad compound that I can use for both like HP+. Thoughts?

If you dont mind the noise/dust of HP+ , then get them.

You have to get the right equipment for the intended use. Rcomps also cost a ton, but you dont see people running all season touring tires on track either ;)

By mis-matching rear pads like that, you have a tendency to heat up the front pads a lot quicker.... which may/may not be a bad thing on a lighter car such as the E30. :dunno

Seems like a lot of people do. Rear racing pads are a lot more expensive than fronts for e30s.

I am also considering a pad compound that I can use for both like HP+. Thoughts?

Matt, my only point, FWIW, is that HT10's bite HARD, and last forever when they get to temp. OEM pads warm up fast, then fade. The vast differential in warming-up performance & at-speed performance can really unsettle a car, and can give your ABS system real fits.....especially at a brake-intensive track like Road Atlanta. If you had a pad that had a bunch more bite than stock in the rear, you will get a lot more balanced bite at speed/at temp.

JMHO...

I think an important thing about swapping pads is to have a similar pad compound.
At least that was what I was told by Carbotech.
Then again, maybe they were just trying to sell me more pads. :eek:

Nope. The different pad families do not like to be used on the same rotors. BTDT and threw away more than one set of rotors as a result.

AFAIK Carbotech is the only race pad mfgr that uses a ceramic base. Hawk is carbon-metallic and Porterfield is carbon-kevlar. Its been so long since I've used PF I wont guess at their pad composition.

Oh thanks for bringing that up, the ABS is disabled on this car, thanks to a PO who cut all the wires to the front struts. :mad

I can see what you guys are saying about the pad differences causing issues. Thanks.

First, I'd suggest not jumping to a race pad too quickly. I found the HP+ was a sufficient improvement over OEMs on my 99 M Coupe. I tried Hawk Blues all around and ate up the rotors in two weekends, but must admit I left them on for the 5 days between events. Rotors were 0.4mm below spec. I decided to try Carbotechs and was advised that I'd need to replace the rotors because of an incompatibilty with the Hawk compound. The Blues were great for bite, but I've decided I can't afford that much stopping power just yet.

Since you haven't experienced fade yet, I stay with either the OEM pad (Jurid, I think), or one of the very good street-able light-track compromise pads (PF Z (my street pad) or any of a lot of others).

In this way, you save yourself the major hassle of swapping pads at the track. Particularly if you are running street tires (which you should unless you are experienced -- see other treads on this), OEM pads will probably stop your car fine for a while (until you get faster).

I am about the try a set of Carbtotech 10F / 9R in the hopes of running them on the street (during the summer track season). My usual pad, PF 01F / 97R makes horrible sticky black dust that, once wetted, is like glue. They also stop like crap when stone cold -- too dangerous for the street for me.

I am about the try a set of Carbtotech 10F / 9R in the hopes of running them on the street (during the summer track season).

I run that combo on my race car and I am very happy with it. Its not street driven at all but on the track the pads seem to come up to temp very quickly (like 1 corner). The XP dust seems to wash off easily and not damage the wheels even when its left on for months at a time. Hope they work out for you.

Re the PF Z pads: I had them on my truck for a couple years and hated them. I've since switched to Bobcats and they are by far the best pad I've ever had on it.

I run Carbotech XP-8 F & R on the street and swap front pads to XP-10 for the track on my 98 m3. That combination seems to do pretty good.

Matt,

I ran the HP+ at MidOhio and the temperatures at the track were pretty hot. No fade, no problems at all.

I know you have some more go wit h the M50, but I was hitting 120 on the back straight and frankly, using my brakes too much - still no fade.

Seems like a lot of people do.I, personally, love utilizing Straw Man arguments to justify particular racing setups.

I, like at least a handful of SpecE30 racers, run HT-10s in the front and rear. The car feels much more balanced and stable under heavy braking, and it will still rotate when asked.

Rear racing pads are a lot more expensive than fronts for e30s.

:confused That's not the best argument for choosing a particular part on the single most important mechanical system in your car.

Also, rear pads generally last 1.5-2x as long as your fronts, unless your master cylinder/brake pistons are shot, or you've adjusted the F/R bias.

I'm not a spec e30 racer. :dunno

Don't get me wrong, just because everyone does it doesn't make it the right thing to do, but I get the feeling I would've heard about it if this was a really fantastically horrible idea.

So what's the feeling on HP+ fronts and HPS rears? There is no HP+ rear... :dunno

Edit: For street and track driving.

Don't get me wrong, just because everyone does it doesn't make it the right thing to do, but I get the feeling I would've heard about it if this was a really fantastically horrible idea.

So what's the feeling on HP+ fronts and HPS rears? There is no HP+ rear... :dunno



There is an HP+ rear - Bimmerworld has them. Others should have them too.

I have HP+ for front and rear - I did not run the HP+ in the rear last weekend - had Pagids instead - the HP+ dont have the little clips on them, and the rattle about (need to fix that somehow). I felt more balanced running HP+ all around than I did HP+/Pagid. It wasn't unmanagable, but not the same feel.

I'm not a spec e30 racer. :dunno

Don't get me wrong, just because everyone does it doesn't make it the right thing to do, but I get the feeling I would've heard about it if this was a really fantastically horrible idea.

So what's the feeling on HP+ fronts and HPS rears? There is no HP+ rear... :dunno

Edit: For street and track driving.

Honestly if you are just doing some track don't bother switching at events. Just redo your brakes and get HPS all around and go from there. Those pads are so cheap they are worth trying right? Then if they aren't adequate for your level of driving upgrade to a "race" type pad. Don't even bother mixing front and back.

Personally I've used the HP+ and I think they suck at the track. I was getting a lot of fade on a 70 degree day at Limerock which is very light on brakes.

I myself use HT-10's on the street and don't think they are that dangerous but I wouldn't recommend it unless you are a hard core/lazy enthusiast. The Blues work well but they are absolutely HORRIBLE for your wheels and death to rotors when cold. I think that's why people bad mouth them. When they are hot they are actually not that bad on rotors but how many of us really measure, tune, and know our brake temps at the track or street? The metal powder from the rotor sticks to your wheels and starts to rust destroying the finish so wash frequently if you decide to go this route.

if i may toss in my $0.02
with an E36/M52 the HPS's do just fine for DE-1&2
im going to GUESS your looking for AX/DE-1/DE-2 set up

the best bet would be new rotors, SS lines and HPS all around, RA is hard on brakes (so i hear) but if your only doing 2 events per year right now thats all you need.

later on i would look at getting OE pads and HP+/10's all around (keeping at least HP+ in the rear for the track) then take a scrubbing pad and scuff up the rotors when you swap pads to try and clear off pad build-up

as i understand it, you DON'T want to mismatch F/R compounds
ie Race F / Street R or vice-versa

Good Luck Matt
hopefully I'll be down for the next BMW AX

Honestly if you are just doing some track don't bother switching at events. Just redo your brakes and get HPS all around and go from there. Those pads are so cheap they are worth trying right? Then if they aren't adequate for your level of driving upgrade to a "race" type pad. Don't even bother mixing front and back.


They are still considerably more than OE pads for me.

Blues aren't even on the table anymore.

And neither Bimmerworld or Turner have a rear e30 HP+ on their websites. I guess I'll get on the phone and order some when I get to that point.

I progressed from OE (Jurid) to HPS to Axxis Ultimates to Ferodo DS2500 to Cobalt SpecVRs. Each pad had higher temp capabilities than the previous pad and served its purpose at the time. If I were to do it again, I would probably skip the HPS and move from the Jurids to the Axxis Ultimates. The Ultimates are cheap and have higher Temp capabilities than HPS and I thought they had better bite. The Ultimates should hold up well for a beginner. Eventually, you'll get pad deposit with these but that should be far in the future.

Eventually, you'll get pad deposit with these but that should be far in the future.

That or glazing :embarrasm

A bit OT but related: does anyone here "bed" their new rotors?

Wilwood has a tech paper that describes rotor bedding as a distinctly different process from bedding pads. According to them, heat cycling new rotors prior to hard use is important for extended rotor life. They recommend doing this with old (and/or street) pads before bedding track/racing pads.

They describe the two objectives as:

rotor bedding: hardening the rotor face by heat cycling
pad bedding: outgassing pad adhesives and depositing pad material onto the rotor faceThey seem to have no issues with switching pads, as long as you allow a few braking cycles to wear off the previous pad material.

I'm far from being an expert but from what I've learned about metallurgy, this makes some sense.

A bit OT but related: does anyone here "bed" their new rotors?

Actually, the Brembo rotors and pads that we use come pre-bed. The rotors have already been heat cycled and bed-in using the same pad compound that we use (there's already dust in the grooves when we install the rotors). The pads come pre-bed as well. Pretty cool stuff!

That or glazing :embarrasm

I had glazing (loss of friction) with the HPS, pad deposits with the Ultimates and DS2500. HPS were the only pads that actually caused problems at the track. With the Ultimates and DS2500, they were just annoying on the street, stopped fine at the track. All of the above was with street tires. Probably couldn't have gotten away with these pads with R-compounds.

I bed in new StopTech rotors. I also bed in new race pads, even of the same brand & model, since there may be some variation of build quality.