Brake pad thread for road course (yes another one)

[Pentalab]

Now the main subject – It doesn’t matter if you have a 225, 265 or 335 tire if the outside diameter and overall inside offset is the same. (Measurements from the inside bolting surface to the edge of the rim / tire sticking in the fender well) What this means is that only so much of the tire can be set to the inside - All the extra rubber and rim is set outward. Since only so much tire can stick in, it doesn’t matter if you have a 225, 265 or 335 tire. Both sit as far in as possible. All extra tire width is set outwardly. With the strut OD that I currently have, no more inside offset is possible. Maybe your struts are thinner. If they are, it can’t be by much. Maybe I’m wrong. If you want to get a tape measure and measure your rim / tire combo for inside offset we can compare notes. Maybe your S197 platform is different - Mine works. If you blow the pic up in my original post you can see the size of the dimple and it is oversized. Even if the dimple were bigger, the tube would out flow a ribbed, flexible tube.

Ideally, a 9.5" rim would have a 36mm offset. Your 9.5" + 45mm offset is what is causing issues. You could add a smaller wheel spacer, like a 3-5mm to gain some inboard clearance.

 

[2008 V6]

Ideally, a 9.5" rim would have a 36mm offset. Your 9.5" + 45mm offset is what is causing issues. You could add a smaller wheel spacer, like a 3-5mm to gain some inboard clearance.

The original intent was to upgrade to an 11” square setup when the driver became more competent using a 295 – 30 – 18 slick. Small OD and would have looked odd but worked well with the NASA TT formula I intended to build the car around - Doable by shortening the axle & tubes. The cost of shortening the axle and tubes would have been offset after a few sets of tires. Being able to rotate the tires would have extended their life for practice events.

The original rim purchase was to keep tire contact patch width down and use maximum inside offset to develop a braking system that could be used later on as we upgraded to proper tires. The 295 – 30s were a much smaller OD so the dimple on the tube could have been smaller – possibly not necessary I don’t know. We never upgraded and the car is 100% street now. The driver had another off road adventure / sight seeing tour and called it quits

 

[Vorshlag-Fair]

I'm not trying to prove anything or be rude...

Our V6 Was purchased for $5,000.00 as a training tool to keep speeds down and for specific NASA TT classing – C or B. If totaled, low initial investment for a learning tool. A very easy platform to upgrade also parts are cheap and in most junk yards, fenders, doors, ECT.

The tires were purchased for dual purpose – Street, Track, Training. In a heavy car with narrower tires, lower over speed is kept with reason for training - The driver could reach the limits at a much lower speed, have fun and not reach the pucker factor. Repetition - Training their personal non-thinking and thinking motor skills in a safer / slower environment. Meaning self-automatic correction with out having to think about it for car control. With some seat time you automatically make small corrections when the car is skiterish not even thinking about it – It just happens – Much, much easier to learn when at lower speeds with an easy to read tire. I would think you might be familiar with this.

Ahh, OK, so now many of your choices make more sense. You never stated that the car was built around a skinny wheel/tire on purpose until here, unless I missed it earlier. You act like I should know that about your car - sorry, I didn't. I get it now - this car is running skinny, street compound tires because this is a trainer car. But you have aggressive brake pads and ducting? I guess that's for reliability, too.

We just built a similar trainer track car for a customer using a 2003 Miata, which we tested for the first time on track last weekend (MSR-C 3.1). We also purposely kept it on somewhat narrow street tires (225mm Rival-S on 15x8 wheels) to keep the grip levels down, but we added aggressive brake compounds to allow him to explore harder braking, then added brake ducting to keep the brakes consistent. It still has pretty amazing cornering speeds, but not what it would have on Hoosiers.

But we also built it around a NASA TT class (TTE), because it will likely end up there. And won't need any changes to be point-maxed for this class. So while it was a "trainer car" it was also built as a dedicated race car, with all of the safety upgrades normally seen in a W2W car, since it could easily become one (TTE/PTE) in the future. And you can never be too safe...

My point was that most people I know who are building S197 track cars DO care about lap times, and thus won't be running 265mm street tires unless they are severely budget constrained. So if they run a 10" or 11" wide front wheel, which they should, the hard ducted brake hoses you propose won't likely work well for them. Your trainer car is somewhat unique in that it has skinny wheels/tires, yet dedicated brake ducting. I think you are trying to argue that they will work for most S197s because you think the inboard wheel clearance is about the same on all wheels... but I think that's not the case.

Now the main subject – It doesn’t matter if you have a 225, 265 or 335 tire if the outside diameter and overall inside offset is the same. (Measurements from the inside bolting surface to the edge of the rim / tire sticking in the fender well) What this means is that only so much of the tire can be set to the inside - All the extra rubber and rim is set outward. Since only so much tire can stick in, it doesn’t matter if you have a 225, 265 or 335 tire. Both sit as far in as possible.

Well.... I will respectfully disagree here, because it almost always does matter. Most folks won't stuff the wheel as far inboard if they are running a 235mm tire (factory fitment for a lot of S197s) vs a 315 (which we can fit with the right wheel).

The outboard edge of the tires on the 18x8/235mm tire (left) and 18x11/295 tire (right) aren't all that different

The inboard wheel offset is going to very likely be very different on a 235 vs 315 tire on an S197. As are most offsets for other wheel and tire sizes in between.

All extra tire width is set outwardly. With the strut OD that I currently have, no more inside offset is possible. Maybe your struts are thinner. If they are, it can’t be by much. Maybe I’m wrong.

Look, I get what you are trying to prove here, but it rarely works that way in practice unless you are trying to keep the track width super narrow on skinny tires. The opposite is usually the goal - where most wheel/tire widths/offsets used on a track car are usually pushing the outside of the tire out as wide as the fenders comfortably allow, to maximize track width. Because more track width adds more mechanical grip. Old racer trick. Also, with the wheels pushed to the edges of the fenders, it makes all wheel widths "look" better". This is just one of those known "style tricks" wheel makers will tend to maximize.

So I'm saying the opposite is usually the case from what you propose ("inboard wheel spacing is almost always the same"), in the real world. We've probably put more than 1000 wheels on S197 Mustangs, and that's just how they tend to be made.

We ran the same car on 18x11F/18x12R (left) and 18x9 F&R (right) at different times, but the outboard track width is similar

Therefore I highly doubt that you have a 265mm tire as close inboard to the strut as we run with the 18x10 or an 18x11" wheels. Strut diameters/widths are very similar among all strut styles and brands, by the way. We ran our S197 on 18x9's and 265mm tires (above right) for a long time (2010-2012, restricted to those limits for SCCA STX class) on several sets of 18x9" wheels - but each set still pushed the track width out as much as possible, which made for massive inboard tire-to-strut clearance on this skinny wheel setup. With the 18x10" if got much closer, and the 18x11" (above left) it was down to about 3mm clearance from inside of the wheel to the strut. Very very close. There's also slop in the strut bracket-to-spindle bolt holes, which we have to maximize for the 18x11" front wheel fitment (pulling the spindle outboard to maximize inboard wheel room).

Maybe your S197 platform is different - Mine works. If you blow the pic up in my original post you can see the size of the dimple and it is oversized. Even if the dimple were bigger, the tube would out flow a ribbed, flexible tube.

Again, I don't doubt that with a 265mm tire (which we have used extensively for 3 years of racing on our 2011 GT) you might get away with a hard brake duct up front. I'm just saying that MOST people will tend to use a WIDER wheel than your trainer car, and when you do so you almost always need to push the wheel even closer inboard to fit the 10" and more so on the 11" widths we tend to use on most customer's S197s.

And the "early" and "late" S197s are virtually identical. They share the same strut towers, lower control arm lengths, strut diameters, and fender clearances. Jon @ Vorshlag's (see above) "early" S197 has our 18x11" wheels on 295mm tires, and he's about to switch to 315s. They fit under stock fenders of his 2007 GT almost exactly the same way they fit on the 2010-14 cars.

No more need to argue your point - you win. On your trainer car with unusually narrow wheels and tires you likely can get away with hard brake ducts (dimpled). But... for most folks this is a dead end. I'm trying to save people the hassle of finding this out the hard way, which is why I keep responding to your posts in ever greater detail. Most track oriented S197 owners AREN'T running that narrow of a wheel IF they have gone to the effort of adding brake ducting. If we felt we could get away with running hard brake ducting, we would have done this years ago and would sell a kit - believe me, I'd much rather see hard ducts whenever possible, because they outflow corrugated brake hose. But they just don't fit the vast majority of S197 track cars.

Generally folks are getting the BIGGEST mods out of the way first, and on these heavy cars the widest tire and wheel package you can run is one of the FIRST things tackled. Well, they should do springs/shocks/camber plates before they ruin their big fat tires, to limit body roll and shoulder edge wear on their tires. But tires make the MOST difference to lap times than anything else... its the biggest improvement people will ever see.

Cheers,

 

[2008 V6]

Ahh, OK, so now many of your choices make more sense. You never stated that the car was built around a skinny wheel/tire on purpose until here, unless I missed it earlier. You act like I should know that about your car - sorry, I didn't. I get it now - this car is running skinny, street compound tires because this is a trainer car. But you have aggressive brake pads and ducting? I guess that's for reliability, too.

We just built a similar trainer track car for a customer using a 2003 Miata, which we tested for the first time on track last weekend (MSR-C 3.1). We also purposely kept it on somewhat narrow street tires (225mm Rival-S on 15x8 wheels) to keep the grip levels down, but we added aggressive brake compounds to allow him to explore harder braking, then added brake ducting to keep the brakes consistent. It still has pretty amazing cornering speeds, but not what it would have on Hoosiers.

Same here – Driver drove the car stock. Then basic suspension up grade. I then had her cook the brakes to see and feel brake beginning and maximum fade. Upgraded the brakes then had her cook them on non-aggressive compounds. Then ducted and up graded compounds for consistency. I was looking for a heavy, low HP, long wheel base car to develop over a 3 to 4 year period for her to eventually compete in. The S197 platform fit the bill. Newer looking, parts cheap everywhere and easy to upgrade – Lower beginning speeds and slower for the rear to kick out / easier to read & catch – long wheel base. I also wanted her to street drive it daily for the first 2 years to practice footwork. In the beginning, she had no concept of a proper downshift or weight transfer – Braking & Acceleration.

But we also built it around a NASA TT class (TTE), because it will likely end up there. And won't need any changes to be point-maxed for this class. So while it was a "trainer car" it was also built as a dedicated race car, with all of the safety upgrades normally seen in a W2W car, since it could easily become one (TTE/PTE) in the future. And you can never be too safe...

As I have stated several times before. (It is not a question of if you are going to crash it is a question of when.) One reason for our bigger trainer. I purchased a Maximum Motorsports Roll bar with cross brace and harness support the first week after I purchased the car. I was on line to purchase a proper race seat & harness when I was stopped. The driver didn’t want to lose use of the back seating area. I stile have the roll bar and hardware in my shop if anyone wants it.

My point was that most people I know who are building S197 track cars DO care about lap times, and thus won't be running 265mm street tires unless they are severely budget constrained. So if they run a 10" or 11" wide front wheel, which they should, the hard ducted brake hoses you propose won't likely work well for them. Your trainer car is somewhat unique in that it has skinny wheels/tires, yet dedicated brake ducting. I think you are trying to argue that they will work for most S197s because you think the inboard wheel clearance is about the same on all wheels... but I think that's not the case.

You miss understood what I stated.

Originally Posted by 2008 V6 View Post
Now the main subject – It doesn’t matter if you have a 225, 265 or 335 tire if the outside diameter and overall inside offset is the same. (Measurements from the inside bolting surface to the edge of the rim / tire sticking in the fender well) What this means is that only so much of the tire can be set to the inside - All the extra rubber and rim is set outward. Since only so much tire can stick in, it doesn’t matter if you have a 225, 265 or 335 tire. Both sit as far in as possible.

I do not think the inboard wheel offsets are the same for all wheels. If the maximum inside offset and outside diameter is the same it doesn’t matter what tire or wheel size you use - The inside clearance will be the same. All extra wheel with from wider tires will move outwardly.
11” over the counter rims were not available when I came up with the idea of an 11” square setup. I was going to have the wheels made. I made a plywood and cardboard rim & wheel combo duplicating a 295 tire mounted on an 11” rim using the same overall inside offset as my current setup. The combo would clear the inner fender at full suspension travel with 7 degrees caster and 2.5+ degrees of negative camber. The ducts cleared my template. I can’t say 1000 percent because I never had the wheels made but no problem

Again, I don't doubt that with a 265mm tire (which we have used extensively for 3 years of racing on our 2011 GT) you might get away with a hard brake duct up front. I'm just saying that MOST people will tend to use a WIDER wheel than your trainer car, and when you do so you almost always need to push the wheel even closer inboard to fit the 10" and more so on the 11" widths we tend to use on most customer's S197s.

Agreed - A wider stance and wheel and tire combo is 100% better. I was trying to kill 2 birds with one stone. Maximum inside offset to develop a brake package and a narrower wheel and tire package to be used for a dual purpose daily driver and learning tool. I tried to keep overall expenses within reason. With the main final goal of upgrading the car in stages the driver could learn from subtle changes also the driver getting track time in a competitive atmosphere to raise the stress levels.

No more need to argue your point - you win. On your trainer car with unusually narrow wheels and tires you likely can get away with hard brake ducts (dimpled). But... for most folks this is a dead end. I'm trying to save people the hassle of finding this out the hard way, which is why I keep responding to your posts in ever greater detail.

I'm not trying to win just stating my experience with pictures and examples. If I can do it, I'm sure others can also. This is also why I keep responding so others can try.

Generally folks are getting the BIGGEST mods out of the way first, and on these heavy cars the widest tire and wheel package you can run is one of the FIRST things tackled. Well, they should do springs/shocks/camber plates before they ruin their big fat tires, to limit body roll and shoulder edge wear on their tires. But tires make the MOST difference to lap times than anything else... its the biggest improvement people will ever see.

Agree - I had to slot my struts and make inserts to obtain 3.3 to 3.4 degrees negative maximum camber - Anything more would and the strut would hit the body.
As I stated before, I am not trying to be difficult or put anyone down. I usually only state what I know from past experience or fact. If I am wrong, I want to be corrected so I may be able to learn. That's one reason I come back to this forum even though I don't have any interest in continuing to modify any S197 platform. There are quite a few sharp people that contribute this this forum which I learn from.

You can see from this pic just how much more room there is for tires up front . 295 no problem on an 11" rim. CLICK on the pic twice to blow it up

 

[dmfracer]

Track pad question

I have a question about track/race brake pads. I want to run Pagid RS-29 on the front in Brembo calipers. Pagid doesn't make a rear race pad for the regular non-Brembo rear caliper, that I can find.

Would it make sense to run something like a Hawk HP Plus pad on the rear for track days? Any reason it wouldn't work?

Car is a 2014 GT non track pack with FR500 Brembos and two piece floating rotors in front, stock GT rear calipers (non-Brembo).

 

[2Fass240us]

I don't know anything about the RS-29 pad, but the HP+ is likely not enough to balance the car. Do you have any information on coefficient of friction on that pad? Or at least an idea as to a comparable pad in the Hawk line?

 

[Mark Aubele]

No information on the Pagid pad, but I wouldn't run HP+ on anything.

 

[JAJ]

I have a question about track/race brake pads. I want to run Pagid RS-29 on the front in Brembo calipers. Pagid doesn't make a rear race pad for the regular non-Brembo rear caliper, that I can find.

Car is a 2014 GT non track pack with FR500 Brembos and two piece floating rotors in front, stock GT rear calipers (non-Brembo).

There is a stock outline Mustang rear pad in Pagid RS56 compound available from a variety of vendors. It's a great compound. Northstar Motorsports has them in their online catalog.

http://www.pagidracing.com/index.ph...=5048da1df64d29f3fc6004e1260b6589&padref=8113

 

[dmfracer]

I've seen those pads but I thought they only fit the GT500 and Boss cars that came from the factory with rear Brembos..... I might have this all wrong. What rear calipers came on those cars and are they the same as the stock rear caliper on my non-Brembo 2014 Mustang GT?

There is a stock outline Mustang rear pad in Pagid RS56 compound available from a variety of vendors. It's a great compound. Northstar Motorsports has them in their online catalog.

http://www.pagidracing.com/index.ph...=5048da1df64d29f3fc6004e1260b6589&padref=8113

 

[JAJ]

Because of the solid rear axle, the same rear brakes came on everything. There are subtleties in how the mechanical parts fit together because of the special setups like the larger rear discs on the 13/14 GT500, but the pads are the same. Even the factory race cars like the FR500S had the same rear brakes. If you've got the OEM calipers with the parking brake cable fitting on the side, these pads will fit just fine. And they come with springs, or at least mine did.

 

[dmfracer]

Great info, thanks!

Because of the solid rear axle, the same rear brakes came on everything. There are subtleties in how the mechanical parts fit together because of the special setups like the larger rear discs on the 13/14 GT500, but the pads are the same. Even the factory race cars like the FR500S had the same rear brakes. If you've got the OEM calipers with the parking brake cable fitting on the side, these pads will fit just fine. And they come with springs, or at least mine did.

 

[csamsh]

I've seen those pads but I thought they only fit the GT500 and Boss cars that came from the factory with rear Brembos

FYI, there wasn't anything that came from the factory with rear Brembos