Brake thermal data

R

rsportvolvo

New member
Does anyone use thermal paint on their calipers and/or brake pad backing plates? What about thermal temp strips on their calipers and disc hubs? What are your caliper, backing plate, and disc temperature ranges?

The reason I ask is that I was reading through AP Racing's website and a Word file I have with clips from various brake manufacturer's on braking system tips. Anyways AP Racing recommends rebuilding calipers that exceed 200 deg. C (392 deg. F) and running cast iron discs between 400 - 600 deg. C (752 - 1112 deg. F).

http://www.apracing.com/info/info.asp?section=Brake+Temperatures_44
 
I would expect that the rotor temp recc's might vary depending on construction/material (where'd your iron come from?).

The paint would be a good idea, though, if you were concerned about it...
 
The Tempilaq system works reliably and is cost effective. Shop around (use Google) as you can find it for <$15 bottle.
 
rsportvolvo said:
Does anyone use thermal paint on their calipers and/or brake pad backing plates? What about thermal temp strips on their calipers and disc hubs? What are your caliper, backing plate, and disc temperature ranges?

The reason I ask is that I was reading through AP Racing's website and a Word file I have with clips from various brake manufacturer's on braking system tips. Anyways AP Racing recommends rebuilding calipers that exceed 200 deg. C (392 deg. F) and running cast iron discs between 400 - 600 deg. C (752 - 1112 deg. F).

http://www.apracing.com/info/info.asp?section=Brake+Temperatures_44
Click to expand...

Well, except for pads and taking off the backing plates/adding ducts, you are supposed to run stock components anyway to be rule compliant. Start with whatever pads/shoes the other Volvo folks run, fresh caliper rebuilds, new rotors, break em in properly and away you go. . (I don't have a Volvo, but am partial to the Hawk Blues myself).
 
Thanks for the responses. I will be using all new components in my brake system. I had a brake failure in my E30 M3 at VIR turn 1 a few years back. Now I really pay attention to the brake system.

The Volvo 240 has 4-wheel disc brakes with 4-pot calipers grabbing vented discs up front and 2 piston calipers grabbing solid discs in the rear. Upgrading the hardware is not legal and not worth the effort (i.e. no performance gain).

I'm looking at the Mintex pad compounds and the temp cut off for some of the compounds is @ 1000 deg. F. I wanted to see what other folks were seeing on their brake temps to get a better idea which compound(s) to select for starters.

My guess is most folks run what others are running and leave it at that. I like to hash out the details.

JimLill recommends the Tempilaq paints. Anyone using the Racetech (AP Racing) or Genesis temperature paints?
 
>> ...Well, except for pads and taking off the backing plates/adding ducts, you are supposed to run stock components anyway to be rule compliant. ...

But there is a huge range of variance in terms of quality, of stock replacement rotors.

From one online source, I could get four different ones for the Golf at one point. I've had the higher-buck Brembo replacements come with wacky core shift issues (so the likelihood of differential cooling inside-to-outside), and cheap-o Autozone rotors that lasted as long as a set of Hawk Blues - that's something like 16 track hours. Some get a zillion spiderweb cracks, others don't. I wish I could have documented some kind of pattern but it got lost in the noise of keeping up with service.

K
 
As many here know, I've had serious caliper heat issues over the years -- regularly melt caliper seals to the point of failure. Through a lot of work and a lot of "little" gains, I've managed to get it under control. We can talk some about that if you want -- pm me.

As to your specific question, we just used a pyrometer aimed at the caliper immediately coming off track. And we saw some nasty temps, for sure -- over 500 degress. Pyrometer seems to work, never tried the other stuff.
 
JeffYoung said:
As to your specific question, we just used a pyrometer aimed at the caliper immediately coming off track. And we saw some nasty temps, for sure -- over 500 degress. Pyrometer seems to work, never tried the other stuff.
Click to expand...

No lie there. I lit a ciggie off one at CMP.
 
JeffYoung said:
As many here know, I've had serious caliper heat issues over the years -- regularly melt caliper seals to the point of failure. Through a lot of work and a lot of "little" gains, I've managed to get it under control. We can talk some about that if you want -- pm me.

As to your specific question, we just used a pyrometer aimed at the caliper immediately coming off track. And we saw some nasty temps, for sure -- over 500 degress. Pyrometer seems to work, never tried the other stuff.
Click to expand...

Are you still running the HT-10's? They seem to hold up great to heat. I'm only running bent backing plates with a hole in the finder liner, and they're not halfway worn out after 10 race days on them.
 
I guess everyone is busy dealing with service and other issues vs. logging brake temps. I can appreciate that as many race weekends are quite hectic. I prefer not to scratch my head as much if I have braking problems. At least I can't say I didn't know the temps where too high or too cool by running the temp paint & strips.

As for brake cooling I plan on running 2 ducts to my front brakes:

- one to the disc hub, which is the most common arrangement
- one to the backside of the caliper to cool the pad-to-piston interface. This is to reduce heat transfer to the fluid via the piston. Similar function to titanium "anti-squeal" shims.

Both of these ducting solutions were discussed and endorsed by a Brembo Engineer at the '07 PRI show. Brembo is using a very elegant setup like this on their new line of calipers.

Even with the ducting setup proposed above I want to make sure it's cooling adequately. If the temps are too low I will to know to block off the brake ducts.

My motivation for this exercise to potentially reduce middle pedal time and increase right pedal time. If I can stop faster and more efficiently than the next guy I can spend more time at WOT and subsequently be faster around the track. All with very little (potentially very little) work.
 
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James, I do sometimes. I mix between HT-10 for CMP and Blues for VIR and Roebling. I feel like I get a better pedal feel with the Blues, but agree they don't handle the heat as well. I may talk to Carbotech and try their stuff this spring, although is playing with fire because I've found something that works.

Rsport, a couple of things we learned on ducting. Make sure the ducts are as close to the centerline of the car and as "in the airstream" as possible. I used to have sort of half-assed things hanging below the bumper at an angle. My present setup is much better.

Also, make SURE you are using as much rear brake as you can get away with. Doing so makes the fronts work less. Obviously, you don't want the rears locking first -- big trouble there -- but you do want them doing some slowing down.

Another overlooked area is the wheel. Talk to wheel manufacturers -- you want as much open area in the wheel and some even claim the spokes in the rim help extract air from the brake/hub assembly.

If you have a brake challenged car, you can't get away with much less than Castrol SRF. Motul works in my car, but barely. The rest -- Ford HD, ATE, Wilwood, just don't.

Then, there are two other items of debatab legality you can try if you want. I happen to think both are legal.

1. Brake fluid recirculator. This pushes new, cooler fluid into the caliper with each stroke of the pedal. I think this is legal based on the rule that says brake circuitry may be revised, but I don't run it. It's not fluid boiling that is causing my problems as much as caliper seal failure from caliper piston heat.

2. Titanium shims or other heat blocks/sinks on your backing pads. Again, I argue that this is legal via the brake pads are free rule, but we debated it here for a while and some disagreed. I do run these, and find that they help keep heat off the piston - at a cost. The cost is once the pads get down to 1/2 or less, the shim traps so much heat on the rotor side of the caliper that the pads pretty much just crumble away. So, I have to change pads perhaps more frequently than others, but at least I'm not having total brake failure 1/2 way into a race at CMP due to caliper seals melting.
 
rsportvolvo said:
Thanks for the responses. I will be using all new components in my brake system. I had a brake failure in my E30 M3 at VIR turn 1 a few years back. Now I really pay attention to the brake system.

The Volvo 240 has 4-wheel disc brakes with 4-pot calipers grabbing vented discs up front and 2 piston calipers grabbing solid discs in the rear. Upgrading the hardware is not legal and not worth the effort (i.e. no performance gain).

I'm looking at the Mintex pad compounds and the temp cut off for some of the compounds is @ 1000 deg. F. I wanted to see what other folks were seeing on their brake temps to get a better idea which compound(s) to select for starters.

My guess is most folks run what others are running and leave it at that. I like to hash out the details.

JimLill recommends the Tempilaq paints. Anyone using the Racetech (AP Racing) or Genesis temperature paints?
Click to expand...

Sorry, didn't mean to hash on the science - its just often easiest to start with a known good condition and then go from there with your experiments. Brand of paint shouldn't matter much - put some on and see what you get. I tried ducts thinking I need them as my front caliper seals burn away after a couple seasons, but it didn't help performance any, and hurt it in the early laps. Usually you just run one vent to the center and let the vanes pull air through the rotors - curved vanes better than straight for that. I went to change rotors and mine have spider cracks all through them, but after years of racing on them, they still mic up new! Just lucky on my brakes I guess. Didn't realize the 240 had such good brakes.. I was thinking of the older ones with disc/drum...
 
Hey Jeff,
If the pad backing plates pass some air between the piston and the pad, the pads will pass along less heat. Pads are free. Some air slots cool the pistons. MM
 
Good point. Just goes to show even when you think you have thought of verything, you have not.

Thanks for that.
 
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