Need Upright/Spindle Information, ++++

[tyoneal]

Originally Posted by David Pozzi

Ty,
First, thanks for the compliment, but I can screw up just as bad as anyone, just ask my wife.

"I have the 245 mm for the front so I can run a matching set of Sumitomo HTR Z Tires. I am expecting to go through several sets taking lessons and they seemed to be the best bang for the buck in the 315 mm size, otherwise I would have the 255 mm."
Not sure I understand the above, 245's are limiting, 255's are getting there, 275's are where you'd like to be if you can manage to clear everything and be as low as you'd like. Are you saying Sumitomo does not make a 255 or 275?

Not in the same Type of Tire. The HTR Z were the only ones at the time anyway, that would be matching AND offer the 315 width. No 335 mm are made by them or I would have chosen them.

I agree a compliant suspension is best, many guys haven't driven a "good" car, so they don't have a good frame or reference about how good their setup is, or how much better it could be. You can instantly go pretty quick by making the car super stiff, but to go faster you then need to soften it a little and give the shocks a chance to do their magic and keep the tires in contact with the road. Another pet peeve I see a lot is: you can have a balanced setup but have too much front brake bias which will put the car into an understeer mode on corner entry.

I'd like to see how the weight jackers were installed. The easier the shocks and weight jackers are to adjust, the more likely you are to take advantage of them.

I know Phil Schmidt, he used to vintage race a Lola T-70 like mine, - great guy!
David

David:

Do you know Casey Putsch? He currently has a Lola T-70 for sale that I have been looking at. it's a beauty, are you familiar with it, or him? He races it at vintage races on the West Coast.

Were the Economy not so Strange, I might take a shot at it, they have always been a favorite of mine, along with the GT40's, and of course the 917's, those were the 3 cars I watched as a kid when they were racing Le mans.

Anyway, another question I have:

I have heard that when choosing the right tire and width, you design a car, then depending on the cars weight and the downforce generated by the aerodynamics of the body and ground effects, you then use the tire that would best serve the speed and the weight including downforce, and the turns they would have to negotiate.

It basically becomes a function of optimizing the pounds per square inch placed on the surface area of the tire that is in contact with the pavement. Too Small, and they bite good, but there is not enough tire to keep the weight of the car from pushing it off the road.

From the opposite perspective, to large, and the psi on the tire patch is not great enough for the tire to bite properly, and even though you have plenty of width, it is unable to attach itself to the road well enough, thus the weight of the car again pushes the tire and car off the road.

The Tire pressure, compound, and the temperature of the surface of the track and tire, allows someone to use somewhat different width tires, compounds, within a specific temperature range and pressure and have the equivalent amount of adhesion with a given weight amount.

In other words, AFTER you design the car, will you then choose the types and widths of the tires. That said, I wish I knew the formula for this. Then I could take the weight of the car and get a decent idea what the optimum tire width for it would be, instead of just trying to shove as much tire underneath the car as I can.

What are your thoughts on this, and more importantly do you have the formula for this answer?

Thanks again for your thoughts.

Regards,

Ty

[FreddieCougar]

I plan to move the engine rearward as possible without destroying the firewall and dash, and saving weight where I can. Engine is a worked over LS3, behind it is a Tremec 3550, 5-Speed.

Does anyone make a subframe that I can Run the parts I have, would be lighter, and allow for some Large Front Wheel/Tires? (295-315 Range)



I agree with David, moving the engine back would help incrementally, but not enough to justify the effort. You can run most of you parts with our sub, with the exception of the steering box. I don't know of any aftermarket sub that has any provisions for the stock box. Your arms and your anti-roll bar will work. The shocks may work, but we have not installed that particular shock on our sub, so we can't guarantee it. You will have room for a 275 in the front. It is hard to put together a cohesive package with parts from a variety of manufacturers, as we (manufacturers) can't possibly test/verify every part out there. I have found that most of the time, the best results come from using one vendor for everything, whether you are talking suspension, ignition, paint, whatever. Hope that helps!
Tim

[Silver69Camaro]

Ty,
I think you're making this too complicated.

All you need to do (on our cars) is put the largest front tire up front as possible, and but a rear tire on that is about 15% larger, more if you have tons of power.

Our frame can accept a 295mm with our splined bar and minimal steering stops, but I'd only recommend if this is a serious track car. Be realistic now. Too large of a tire takes more heat to work properly...if the heat is not generated, you might as well step down to a smaller tire. Brake rotor sizing works the same way.

There are formulas for what you describe, but honestly, they don't really work for what we do. People outside of OEMs don't have the tire data needed for such calculations; even if you did, it's only a starting point. Most racing teams run the largest tires that rules allow.