Brake and Tire Questions


conundrum

GT Owner
Feb 7, 2007
61
Kentucky
1. I'd like to improve the braking for track days but still keep brakes suitable for road use. Any ideas?

2. Who makes tires for the stock wheels besides Goodyear and Hoosier? Anyone?
 

Fast Freddy

GPS'D 225 MPH
Mark II Lifetime
Aug 5, 2005
2,727
Avondale, Arizona
for the brakes you more than likely just need a harder race spec pad and high temp race brake fluid. that should be sufficient. if not a 6 piston caliper is available for the front with slotted rotors. i think hoosier makes slicks in a size that fits the GT now.
 

californiacuda

GT Owner
Mark II Lifetime
Oct 21, 2005
919
The 1st and most important change to make is stickier tires. As long as the standard brakes are working ok, it is the tire to road contact that makes the biggest difference.

Ask 99% of aftermarket brake companies to provide testing to demonstrate shorter stopping distance.

If brake fade does occur while tracking, than brake cooling ducts, larger rotors to help shed heat, higher heat pads, and better grade brake fluid for higher boiling temp are helpful.

Most big brake kits are for bling only, and if the front/rear brake bias is not addressed, braking distance may actually increase.

Lowering a cars height will surprisingly, usually reduce stopping distance. Sorry for the long answer.
 

conundrum

GT Owner
Feb 7, 2007
61
Kentucky
I understand about the tires. Are Hoosiers the best available for stock wheels?
 

californiacuda

GT Owner
Mark II Lifetime
Oct 21, 2005
919
Hoosiers are great track tires, if you're going to run the same tires on street, may want to think about michelins, pirellis, and others
 

Ed Sims

GT Owner
Mark IV Lifetime
Apr 7, 2006
7,926
NorCal
tires, brakes, etc

Hoosiers are the only sticky DOT rubber that fit the stock GT rear wheels. There is a rumor that Michelin will make the size we need for our rear wheels in their Pilot Sport Cup line eventually. It is a sticky DOT tire with more grooves than the Hoosiers. But, don't hold your breath regarding Michelin's decision! If you are like me & only drive in the dry the Hoosiers are fine. They will last around 2500 miles if you throw in a few open tracks. Sticky DOT rubber is less expensive than the harder compound all weather tires like the stock Goodyears. I only made my stock rubber last 6000 miles (even the fronts) because of open tracks & aggressive road driving.

The stock brake rotors & pads work great on the track. I drive hard in the open track advanced run groups with only a little fade at the end of a 20 minute session. Changing your brake fluid regularly is the best thing you can do. I am now running the SVT 2-piece floating rotors which help a little but they are not worth the cost for the performance advantage. They are definitely worth the cost for their trickness factor however! And lighter.

Lowering my GT helped braking & cornering. I am running the T&A shocks by Penske. There are other past threads on tires, brakes & shocks if you go to the search feature of this site. Good luck.

Ed
 

californiacuda

GT Owner
Mark II Lifetime
Oct 21, 2005
919
I am currently running Pirelli pcorsa asimetricos on the rear of my GT, with stock rims. The tire size is 345 30 19 no rubbing trouble, more grip, street legal treads, soft 90 wear rating. They seem to grip rather well. Same diameter as stock.

Probably better tire for street and some track. The Hoosiers are better for track and some street.
 

kjslider

GT Owner
Mark IV Lifetime
Mar 1, 2006
360
socal
I am currently running Pirelli pcorsa asimetricos on the rear of my GT, with stock rims. The tire size is 345 30 19 no rubbing trouble, more grip, street legal treads, soft 90 wear rating. They seem to grip rather well. Same diameter as stock.

Probably better tire for street and some track. The Hoosiers are better for track and some street.

The Pirelli's sound like a good choice. The stock tires suck:thumbsdow

The Hoosiers are good for a half dozen or so heat cycles before they start giving up much of their grip. I've gone thru dozens of sets that still have plenty of rubber left but have gone greasy.

Just fyi
 

barondw

GT Owner
Sep 8, 2005
1,109
The Hoosiers while street legal cannot be used on the street. They basically have no tread, just two grooves. Any wet condition or road with anything on it, except dry pavement, will create an very serious unneeded risk.

The stock brakes last less than 4 - 30 minutes sessions at Watkins Glen. So a 2day event requires extra sets of brake pads. Also remember the GT will not last 40 minutes at the Glen because it will run out of gas in 25-30 minutes.

Look for previous posts by Trackday on this subject.

Dave
 

roketman

GT Owner
Mark IV Lifetime
Oct 24, 2005
8,095
ma.
don't worry about brakes,they only slow you down!
 

conundrum

GT Owner
Feb 7, 2007
61
Kentucky
Thank you one and all for the responses. There is some very good info here.
 

STORMCAT

GT
Mark IV Lifetime
Le Mans 2010 Supporter
May 25, 2006
7,580
Ft. Lauderdale
I am currently running Pirelli pcorsa asimetricos on the rear of my GT, with stock rims. The tire size is 345 30 19 no rubbing trouble, more grip, street legal treads, soft 90 wear rating. They seem to grip rather well. Same diameter as stock.

Probably better tire for street and some track. The Hoosiers are better for track and some street.

What tires are you running on the front?
 

Ed Sims

GT Owner
Mark IV Lifetime
Apr 7, 2006
7,926
NorCal
tires & brakes, oh - gas too

I only drive in the dry. If I see lots of water on the street, I avoid it. If it looks like it will rain, I won't drive the GT. Of course, I live in sunny California so dry streets & cloud free days are the norm. I love sticky tires! Even roads have turns. After running the almost no tread sticky tires for years, a regular tire looks like it's for off-road! The Hoosiers are only for L8-apex die-hards though!

I can get three 20 min open track sessions at plenty of full throttle at Laguna, Sears & T-hill on 5/6 of a tank of gas in my stock engined GT (Ida exhaust).

I can also get 8+ sessions on a front set of stock brake pads with enough pad left for plenty of street use. The stock compound is not that bad. I'm also not granny driving my GT.

Ed
 

kosupply

GT Owner/Board of Directors
Mark IV Lifetime
Jan 27, 2006
236
Houston
same as diameter as stock? http://www.1010tires.com/TireSizeCalculator.asp?action=submit

Shows almost 2.00 inches smaller...dropping rear ride height by half that.....
 
Last edited:

SteveA

GT Owner/B.O.D
Mark IV Lifetime
Dec 13, 2005
3,700
Sandpoint Id
Hoosiers are the only sticky DOT rubber that fit the stock GT rear wheels. There is a rumor that Michelin will make the size we need for our rear wheels in their Pilot Sport Cup line eventually. It is a sticky DOT tire with more grooves than the Hoosiers. But, don't hold your breath regarding Michelin's decision! If you are like me & only drive in the dry the Hoosiers are fine. They will last around 2500 miles if you throw in a few open tracks. Sticky DOT rubber is less expensive than the harder compound all weather tires like the stock Goodyears. I only made my stock rubber last 6000 miles (even the fronts) because of open tracks & aggressive road driving.

The stock brake rotors & pads work great on the track. I drive hard in the open track advanced run groups with only a little fade at the end of a 20 minute session. Changing your brake fluid regularly is the best thing you can do. I am now running the SVT 2-piece floating rotors which help a little but they are not worth the cost for the performance advantage. They are definitely worth the cost for their trickness factor however! And lighter.

Lowering my GT helped braking & cornering. I am running the T&A shocks by Penske. There are other past threads on tires, brakes & shocks if you go to the search feature of this site. Good luck.

Ed

Ed, do you know what model or part number one would use to order the Penske shocks? Thanks.
 

SteveA

GT Owner/B.O.D
Mark IV Lifetime
Dec 13, 2005
3,700
Sandpoint Id
Hoosiers are the only sticky DOT rubber that fit the stock GT rear wheels. There is a rumor that Michelin will make the size we need for our rear wheels in their Pilot Sport Cup line eventually. It is a sticky DOT tire with more grooves than the Hoosiers. But, don't hold your breath regarding Michelin's decision! If you are like me & only drive in the dry the Hoosiers are fine. They will last around 2500 miles if you throw in a few open tracks. Sticky DOT rubber is less expensive than the harder compound all weather tires like the stock Goodyears. I only made my stock rubber last 6000 miles (even the fronts) because of open tracks & aggressive road driving.

The stock brake rotors & pads work great on the track. I drive hard in the open track advanced run groups with only a little fade at the end of a 20 minute session. Changing your brake fluid regularly is the best thing you can do. I am now running the SVT 2-piece floating rotors which help a little but they are not worth the cost for the performance advantage. They are definitely worth the cost for their trickness factor however! And lighter.

Lowering my GT helped braking & cornering. I am running the T&A shocks by Penske. There are other past threads on tires, brakes & shocks if you go to the search feature of this site. Good luck.

Ed

Ed, do you know what model or part number one would use to order the Penske shocks? Thanks.
 

SteveA

GT Owner/B.O.D
Mark IV Lifetime
Dec 13, 2005
3,700
Sandpoint Id
Lowering a cars height will surprisingly, usually reduce stopping distance. Sorry for the long answer.

I'm a bit confused? Are you saying the stopping distance is shorter if the car is lowered? This would make sense and not be surprising. I lowered my car and very much like the look but it it hurts the stopping distance I like the look a lot less.
 

californiacuda

GT Owner
Mark II Lifetime
Oct 21, 2005
919
By lowering a cars center of gravity, less weight is transfered during acceleration (braking included). Because there would be less weight transfered to the front of the car, more weight on rear of car and more force can be exerted by the rear braking system.

Road racing cars often have an adjustable proportioning valve to change the amount of rear braking force applied.
 

barondw

GT Owner
Sep 8, 2005
1,109
By lowering a cars center of gravity, less weight is transfered during acceleration (braking included). Because there would be less weight transfered to the front of the car, more weight on rear of car and more force can be exerted by the rear braking system.

Road racing cars often have an adjustable proportioning valve to change the amount of rear braking force applied.

Most cars have bigger front brakes than rear...because of the weight transfer. Most stopping power is up front is required because of weight transfer. The rear brakes are not that critical.
 

californiacuda

GT Owner
Mark II Lifetime
Oct 21, 2005
919
The front brakes do 70 to 80% of the braking. Often times a big brake front upgrade kit feels great when they grab hard and fast. But if you do an annalysis of a cars actual stopping distance, the backs must be properly matched and proportioned to the fronts for high performance stopping.

The back brakes are important also, not just the fronts.