brakes and trans breather

#41

Here is another update to the brake torque order of march.

I’m finding that manufacturer reps really don’t know much about their competition. So if Carbotech says that their XP10 has similar brake torque to Hawk’s HT10, he’s probably pulling that out of his butt.

The XP10 definately has more (as opposed to “similar” ) brake torque then the HT10.

If we can’t trust what pad reps say about how their pads compare to other companies, then that throws some confusion into my brake torque order of march.

This much we know for certain:
XP16>XP12>XP10>XP8
DTC60>HT14>HT10
PFC01>PFC97
XP10>HT10

But the larger relationship chain: XP16>XP12>DTC60>PFC01>HT14>HT10=XP10>XP8=PFC97, is based on too many guesses of relative position of pads from different manufactures

Scott’s guess is that the below chain is closer to the truth.
XP16>XP12=DTC60>XP10>HT14>PFC01>HT10=XP8>PFC97

I was able to figure out this weekend that XP10’s definately had more bite then HT10’s. I put one set in the LF and the other set in the RF. And there was no doubt about it.

I also discovered that Carbotech pads cost more but don’t last longer.

#42

Good stuff ranger.

I used the DTC60s with HT14s in the rear at summit this weekend and I really liked the combination. I got the rear bite I was looking for, so I had much higher entry and mid corner speeds. Unfortunately the better rotation allowed me to slide the car a lot more, which I like but is slower on 888s. If I can adapt my driving style to have a lower slip angle (more subtle rotation), I think this brake pad combo will be faster.

#43

What we ought to do is to just hang on to some of our “almost used up” front pads. Then put pad combos from different manufacturers in front and go run a few laps. If we get some others doing this, it won’t take long before we have all this figured out. Or just send me a pair of almost used up front pads and I’ll try them out.

I have a couple track days at RR yet this month. I can screw with my brake pads there and not get killed. I’d be less motivated to play brake games at RA, for example.

By almost used up I mean 4mm or so. The kind of thing that we replace all the time. I could use all front pad types except HT10 and XP10.

#44

mskeen wrote:

Mike -

Have you tried the XP12 & XP16 combination? Is the XP14 a new compound they are working on? I didn’t see a description of it on their site.

I usually see the more aggressive pad up front (i.e. XP16 front, XP12 rear). What is the rationale for running the 16’s out back?

Thanks,

Steve

PS - I ran HT10s all around this weekend, but never felt very confident under braking. That’s probably because I taped up my ducts for morning “Toy” practice and forgot to untape them for the 45 minute afternoon race. Doh! :huh: Got a little fade going towards the end…

#45

Keep in mind torque is only one of the few characteristics that make a brake pad perform well. Also, mixing pads my be good to oversome some shortcomings of a stock braking system, but you have to be careful - scatter can lead to some interesting results.

Certainly I have my favorite, and feel really good about the ability to close under braking versus cars I have raced against…

Also, testing used up pads is not really going to yield any sort of relevant result. We found that HT-10 for example perform quite a bit differently with a fresh pad versus even half-used.

#46

JamesClay wrote:

[quote]Keep in mind torque is only one of the few characteristics that make a brake pad perform well. Also, mixing pads my be good to oversome some shortcomings of a stock braking system, but you have to be careful - scatter can lead to some interesting results.

Certainly I have my favorite, and feel really good about the ability to close under braking versus cars I have raced against…

Also, testing used up pads is not really going to yield any sort of relevant result. We found that HT-10 for example perform quite a bit differently with a fresh pad versus even half-used.[/quote]

Re. torque is only one of the few characteristics. Understood. But the kind of testing that I can do is pretty limited. And finding out interesting comparative info is better then not finding it out.

Re. pads perform differently as wear sets in. I kinda thought that I was seeing that too, but I was hoping that I was wrong. That does make this more difficult. But again, some testing is better then no testing. In a perfect world I’d be associated with some sugar daddy BMW performance shop that would fund all my whims. Hey, wait…

#47

Back to that subject for a minute:

I installed one of these a couple months ago. Three track days and not a drop of transmissions fluid in the catch bottle. I mentioned it to the guy that installed mine and Gasman’s. He said that there was a slight difference (in his opinion) between my 87 transmission and Gasman’s 89 transmission. His will lose 1/2 a quart in a day, and mine does not. He expected that some design change between the models must account for this.

Just my experience FWIW.

John

#48

John
If the catch bottle is up high enough the fluid never really gets there. We’re only talking about samll amounts of fluid. It will rise in the tube under certain load conditions and then drain back into the gearbox when the car settles. The tube just keeps it from leaving altogether out the breather and leaving you with low fluid level and possible premature failure.

#49

[quote]Ranger wrote:
Re. pads perform differently as wear sets in. I kinda thought that I was seeing that too, but I was hoping that I was wrong. That does make this more difficult. But again, some testing is better then no testing. In a perfect world I’d be associated with some sugar daddy BMW performance shop that would fund all my whims. Hey, wait…[/quote]

Not really - testing that gives a false result that you plan to treat as realistic and fact is really not better than using your best judgement - I think? Unless you just need a project and using time is the goal. Believe me, our goal is to figure out the best stuff out there and I share info :slight_smile:

#50

SGrace wrote:

[quote]John
If the catch bottle is up high enough the fluid never really gets there. We’re only talking about samll amounts of fluid. It will rise in the tube under certain load conditions and then drain back into the gearbox when the car settles. The tube just keeps it from leaving altogether out the breather and leaving you with low fluid level and possible premature failure.[/quote]

Maybe I should mount my catch bottle on the roof. :wink:

Kidding aside, if the catch can is higher than the transmission, I would think gravity alone should keep the fluid in the transmission. My catch can had a little over half a quart after the 8 hour enduro. The windshield washer bottle mounted in the stock position serves as my catch can.

#51

That’s what my guy told me about Steve’s. When test driving it around the “cloverleaf” on a nearby interstate, Gasman’s transmission blew out over a quart of fluid. We guessed that the possible difference in design of the transmission between the two models years (note I said possible), may be causing that. We also thought about the possibility of the fluid never making it to the bottle and running back to the transmission.

John

#52

Gasman wrote:

Gasman -

Is it set up so the fluid can drain back into the tube?

Seems like the tank should drain itself under those conditions.

Steve D.

#53

JamesClay wrote:

[quote][quote]Ranger wrote:
Re. pads perform differently as wear sets in. I kinda thought that I was seeing that too, but I was hoping that I was wrong. That does make this more difficult. But again, some testing is better then no testing. In a perfect world I’d be associated with some sugar daddy BMW performance shop that would fund all my whims. Hey, wait…[/quote]

Not really - testing that gives a false result that you plan to treat as realistic and fact is really not better than using your best judgement - I think? Unless you just need a project and using time is the goal. Believe me, our goal is to figure out the best stuff out there and I share info :)[/quote]

I hear ya, but I’m not really going after subtlties here. Hawk, for example, says that their HT14 has more brake torque then the PFC01. But I’ve learned that the rep from one manufacturer doesn’t necessarily know spit about the products form a different manufacture. So if I do some tests and I find that in every single test the PFC01 seems to have more brake torque then the HT14, then I think I’ve learned something useful.

Clearly that is not the same as tests run at many temps and at different stages of wear.

I’m not saying of course that more brake torque is an objective. Stating the obvious, max brake torque is just one characteristic among many.

So I started with a rep telling me that one pad had more bite then another. And after testing I found that what he had told me was generally not the case. Maybe under some conditions what the rep said would have turned out to be accurate. I can’t exclude that possibility because my tests weren’t all that rigorous.

You suggested that I use my best judgement. Judgement is based on experience. I think that testing provides more information then not testing. And it helps build experience. But god how my judgement fails me sometimes.

#54

Steve D wrote:

[quote]Gasman wrote:

Gasman -

Is it set up so the fluid can drain back into the tube?

Seems like the tank should drain itself under those conditions.

Steve D.[/quote]

No, it isn’t designed to flow back. I guess I could put a pitcock in the bottom of the tank so that it flowed back after the transmission cooled.

#55

The tube goes into the top of the washer bottle. No way for it to drain back. I don’t think I’d want it to drain back anyway. The bottle is also used to catch coolant overflow. You wouldn’t want to mix that stuff in your transmission I’d guess.

#56

Just when I’ve gotten comfortable with my brake bias, Hawk discontinues the HT14 rear for the E30 :pinch:. Nobody seems to have any leftovers either.
If anyone knows where to find them please let me know. If anyone has HT14 rears (new or light use) they’d be willing to part with, I would be VERY interested in buying/trading for them…

Thanks,
allenr00@hotmail.com

#57

allenr wrote:

[quote]Just when I’ve gotten comfortable with my brake bias, Hawk discontinues the HT14 rear for the E30 :pinch:. Nobody seems to have any leftovers either.
If anyone knows where to find them please let me know. If anyone has HT14 rears (new or light use) they’d be willing to part with, I would be VERY interested in buying/trading for them…

Thanks,
allenr00@hotmail.com[/quote]

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