Tire pressure on track

[911teo]

Hi I think I am going to do it...

My other car is not ready yet... so I signed up for a 3-day DE at Carolina Motorsports Park on June 1-2-3 with the Carolinas Mustang Club... and I am taking the GT.

I have ordered Pagid Yellow RS pads and I am going to upgrade the brake fluid (thinking of Motul RBF 600).

I hope the rotors will take a 3 day beating....

What tire pressure do you think is ideal?

It should be hot and sticky here in a couple of weeks....

 

[PL510*Jeff]

Track Pressure

911teo

- if you're tracking with standard Goodyear's start our cold with 30 in the front and 28 in the rears. It is best if you do this the night before.Heat gain will have you ending up with about 4# to a 5# increase. If you get more that that re-adjust down 1# at a time.

Also a bit of negative camber will make the GT turn in more precisely. You'll notice a bit of shoulder wear. Also pay attention to the "tread roll over" after you've been out on the track. If you see it, lower the starting pressures.

Hope this helps. Enjoy your track time.

 

[911teo]

Jeff

thanks! I am using the OEM Goodyears. What camber do you run up front? and rear?

 

[Indy GT]

Track TP

I was told by a FGT suspension design engineer to start with 29 psi Front and 30 psi Rear, cold. This is of course is for the OEM Goodyears. The design team spent many, many laps on the proving ground with our car and many Goodyear designs were tried.
Good advise as posted above, adjust slowly and check tread wear patterns or tread temperatures if you have the equiptment.

 

[Derry]

I spent 4 days at the West track at Bondurant with the GT and found that 26 in front and 32 rear cold was the best combo though it is a tight track.

Derry

 

[Fubar]

I would have the tires Nitrogen filled. If done correctly (you have to make sure they pump it down fill it and do it again) you wont have to worry about gas expansion. It's not that expensive. My Ford dealer did it for nothing (the nitrogen rep happened to show up that day). Then you can put whatever you feel comfortable with in there.

 

[911teo]

Cool, great advice guys....

Camber? Toe? Caster? Any one has details on the best suspension set up?

 

[snaproll]

I would have the tires Nitrogen filled. If done correctly (you have to make sure they pump it down fill it and do it again) you wont have to worry about gas expansion. It's not that expensive. My Ford dealer did it for nothing (the nitrogen rep happened to show up that day). Then you can put whatever you feel comfortable with in there.

I've always wondered about this, being an airplane guy. I've done some research and can conclude that I think this is one of the more commonly perpetuated urban legends of the race track and street. It seems like it makes sense, but the science behind it is not there. Remember, air is what, 78% N2? Then you get into the various effects of moisture but, at the end of the day, the nitrogen rep is the only winner.

Cool, great advice guys....

Camber? Toe? Caster? Any one has details on the best suspension set up?

Yes, I finally got the wheels off the car and discovered it has no struts :biggrin Unfamiliar territory to a Mustang guy. How do you reduce front camber again? I think I'll go to Putnam Park this weekend and would like to dial in some before I grind off the tire shoulders.

Bruce

 

[tiger 6]

Why are the recommended track tire pressures for the GT lower than the street tire pressures? All the street tires I have run on a track[Pirellis, Michelins, Nittos etc] recommend 3-5 psi higher pressures than the cold street setting. A lower pressure would give a slightly higher contact patch but possibly a risk of more roll over on the sidewalls.:confused

 

[Fubar]

I've always wondered about this, being an airplane guy. I've done some research and can conclude that I think this is one of the more commonly perpetuated urban legends of the race track and street. It seems like it makes sense, but the science behind it is not there. Remember, air is what, 78% N2? Then you get into the various effects of moisture but, at the end of the day, the nitrogen rep is the only winner.

I don't know much about the science behind it. I've seen plenty of pro-N2 information (I'm sure it’s pushed by the people who sell the stuff). I have seen several race shops that have the machine there tho... I just trusted that they would have done some research on it before investing in the equipment.

 

[Derry]

Without lowering the pressure the understeer on a the tight track was too great.

Derry

 

[barondw]

Why are the recommended track tire pressures for the GT lower than the street tire pressures? All the street tires I have run on a track[Pirellis, Michelins, Nittos etc] recommend 3-5 psi higher pressures than the cold street setting. A lower pressure would give a slightly higher contact patch but possibly a risk of more roll over on the sidewalls.:confused

Because as the tires heat they obviously build pressure. Running higher pressures than starting at 28/29 will result in over inflation and premature wearing of the center tread. Depending on how agressive you are in driving on a road circuit and its configuration tires pressures can easily rise between 4-7 psi.

This has been covered in other threads and I suggest doing a search for those threads to gain additional insight and information in regard to this thread.

Dave

 

[John B]

For brake fluid use Castrol SRF. It's expensive but worth it. Has the highest boiling point of any brake fluid. I use it in all my race cars and street cars I take to the track occasionally. It worked great in my Ford GT at the track, and on the street.

 

[Ernest]

tire pressure

You can fool with the pressures but in the end you would be much better off with Michelin's Pilot Sport PS2 (front 265-30-19 rear 335-30-20), with the Good Years you spend a lot of time skating around the corners.

 

[Indy GT]

Ernest, while I am sure other Forum readers who actually have FGT's may apprecitate your comments about our OEM tire, I am not quite sure you have the petigree to make the Goodyear skating statement.

I have tracked MY car and found no problems with the tires and I know the research and development Fred's team (that's Fred Goodnow the Ford GT Engineering Manager) put into the Goodyear selection.

Go buy a car and try them out. They really are surprisingly good on the track!

 

[FB GT40]

Tires

Don't want to burst any bubbles - but I too have tracked my GT with Goodyear’s, Pirelli's and Hoosiers. Hoosiers win hands down, Pirellis are remarkably good - and the Goodyear’s are just nice street tires. Ask Tom Rickenbach (sp?) what he thought of the Goodyear’s. Or Gene Martindale. They too worked on the tire set-up. And while you're at it - don't forget some T&A shocks. They are terrific. :thumbsup

G.

 

[B O N Y]

Don't want to burst any bubbles - but I too have tracked my GT with Goodyear’s, Pirelli's and Hoosiers. Hoosiers win hands down, Pirellis are remarkably good - and the Goodyear’s are just nice street tires. Ask Tom Rickenbach (sp?) what he thought of the Goodyear’s. Or Gene Martindale. They too worked on the tire set-up. And while you're at it - don't forget some T&A shocks. They are terrific. :thumbsup

G.

jayzus gordy,... stop putting all your money in your cars and buy your beeeeetch some clothes, aren;t you worried about dumping your bike and covering her with road rash??:eek :eek :willy :eek :eek

 

[richardhead]

Ford GT Alignment Settings

Jeff

thanks! I am using the OEM Goodyears. What camber do you run up front? and rear?

Stock alignment specs are in the service manual. You should put the car on an electronic alignment rack and see how close to stock specs your actual settings are with the tires properly inflated. If not within close spec, align the car. Then, get into the driver's seat and see what changes occur. Then, adjust your tire pressures for your track settings and see what changes occur in the factory settings, without being in the driver's seat and sitting in the seat. Do this with a full tank of gas. These are now your reference settings.

Aligning this car is not easy. The shims are located in the rear top control arms and the front lower control arms. Four retention bolts and four shims per arm. The shims are forged aluminum washers and are anodized to identify the shim size. Three sizes are available for the front (2,3,4mm...according to the Ford GT Dealer Parts Listing. UPDATED INFORMATION 6/17/2007: ACTUAL MEASUREMENTS of these shims, as ordered from Ford Parts, indicate they are really approximately 4,5,6mm sizes...the same as the rear, with larger bolt holes than the rear) and three sizes for the rear (approximately 4,5,6mm with smaller bolt holes than the front). They run around $10.00 each MSRP from Ford. Front and rear retention bolt sizes/diameters are different...watch the torque settings as the service manual shows a higher setting for the front (41 lb.-ft., lower control arrm) than the rear (22 lb.-ft., upper control arm). The front torque may be in error as it is significantly higher than the rear... I am checking on this. The front lower control arm bolts are listed by Ford as M10X65mm and the rear upper bolts M8X70mm.

You must loosen all four bolts, removing the inner bolts first to add/delete/change shims and then remove the outer bolts for shim work after the inners have been replaced. This keeps the control arm in place. When the shims have been adjusted, barely snug the bolts and roll the car so its weight to allows the control arm to settle on all four bolts equally. Then torque the bolts. Remeasure your camber alignment specs and reset toe. Caster changes should be minimal to none. Continue the process until the specs are what you desire...either stock or changed with different tire/wheel combinations.

Do not use any other shims than as provided by the factory. Dissimilar metal corrosion or loss of shims could occur.

NOTE: SEE PARAGRAPH 2 FOR UPDATED INFORMATION: The factory/Ford shims are not exactly what the parts listing indicates. The folks at Saleen measured some shims for me and, for example, the 5mm rear was "actually 4.5mm in thickness" (UPDATE 6/17/2007: MY MEASUREMENTS OF THE ACTUAL SHIM INDICATE IT IS APPROXIMATELY 4.96MM, OR CLOSE ENOUGH TO 5.00 TO CALL IT THAT. THE OTHER REAR SHIMS ALSO ARE VERY CLOSE TO THE PARTS BOOK SPECIFICATION. FRONTS ARE DIFFERENT.). I have ordered a sample of each shim from Ford, and will measure thickness (SEE PARAGRAPH 2). This means, when you produce your camber change algorithm for your particular tire/wheel combination, you need to adjust the degrees of change per shim interchange accordingly. If you don't, you'll find yourself short on removing/adding negative camber.

The key is to maintain some negative camber while maintaining maximum tread face contact under loads. This will balance skid pad holding with tire wear, and provide maximum average traction. Run your tires over chalk dust and see how the tread surface is covered when done. If too much outer edge does not contact, reduce your negative camber accordingly.

The typical car may require as many as four trips to the rack to get the final settings right. If you drive street and track, you may need to go back and forth on settings for each.

I have exchanged e-mails with the engineer at www.humagen.com to obtain most of this information. They are developing alignment guidelines, shim specs and charts for the car to use in conjunction with the wide wheels they have in production/test from HRE. He said they expect to be posting this data within a month or so.

Watch your tire wear and find a good alignment shop! Good luck...

 

[Indy GT]

Richardhead, great post!!
Thanks very much for the step-by-step and all the details.
Very helpful for developing an alignment strategy...

 

[FB GT40]

Rash

jayzus gordy,... stop putting all your money in your cars and buy your beeeeetch some clothes, aren;t you worried about dumping your bike and covering her with road rash??:eek :eek :willy :eek :eek

Bony - Rashes are bad, no matter how they occur! I'll work on some lowers for her!:lol

By the way - the car budget is shot for now. Major house renovation scarffed up all the cash. Look for a Gordo's Garage opening later in the year!!

G.