944CS

It all depends on where your ride height is set at....if the spring plate is parallel to the ground under static conditions then under braking the plate is going to be pointing toward the ground, and your wheelbase will be shortened. Due to the nature of the links this causes the wheel to toe in. Most people, however, have their 944's slammed without relocating any suspension points, thus under static conditions the spring plate is pointing up in the air and, under braking, will move to become parallel with the ground. This elongates the wheelbase and the wheel toes out

Larry Herman

Next time I align my kid's 951, I'll play with the ride height and measure the toe change. I did that with a friend's GT3, and it only changed (gained toe out) 1/8" from static ride height to full droop. Pretty good for over 4" of suspension movement.

333pg333

A couple more things. The n/a 944 vs the turbocharged car will behave differently as you will drive it a bit differently. So comparing a 951 to an S2 will involve different cornering, braking, and acceleration movement...which will affect suspension differently.

Also, bear in mind, you can run A6 on the track successfully. I have done this and they're great. Of course they won't last as long in terms of going off per session, but according to coms I had with a Hoosier tech he said that provided that they're heat cycled in properly they should last as long as the R6 in terms of outright lifespan. Not sure how long you tend to go out for Z-man but if it's sessions of 20 mins and less I'd consider the A6 as an option. For our events which need the tyres to come up to heat asap they were great. But we were only out there for 5-10mins generally.

disasterman

When in doubt call Hoosier! They are very helpful.

A6's are great for autocross and short sprint races when money is no object. They are at maximum performance/grip by the end of the straight. They will not last though.

R6 break in - ask Hoosier, they will tell you that how to do the initial heat cycle and insist that it extends tire life. It is also available on their website. But what do they know?

We have some serious S2's in the NASA Great Lakes region running as much as 4.5% of camber in the front with 285/30/18's. I run a 951 with 245/35/18's in GTS 2 and my current camber setting is 3.2 and will be moving to 4.0 for the next race.

GTS 2's were in the 1:36's this weekend at Mid Ohio on the pro course which is pretty fast for a sub 200 hp 20 year old car.

Lemming

I ran A6's quite a bit last year and they are great if you do not get them too hot. Jeff S. at Hoosier also told me they would last as long as R6's (heat cycles), but this was not the case for me. I got around 12-14 on the A's before they dropped off, R's can last me up to 25 cycles. Of course the number of heat cycles that one gets out of their HoHo's is negatively correlated with their wallet size


I guess camber is car and personality specific, but that seems like quite a bit of camber. I'm pretty good about taking tire temperatures to set camber and for my setup, -3.2F/-2.25R seems to work really well (275/40/17 all around).

disasterman

I have heard good things about the 275/40/17 square setup. I think part of the reason that the S2's are going to 4.5 is to allow the travel of the large wheel tire combo into the stock (but massaged) fender well. I was under cambered at 3.2 and should have taken the time to move it at the track. We spend a lot of time working on set up, test days and gathering data with a variety of set ups. With a larger sidewall of a 245/45/17 it may be better to run a maximum of 3.0, suspension also plays a part. We ran a maximum 3.2 last year with 245/45/17's up front. I am now running on 850# springs in the front so my settings probably no longer apply.

As always, test and tune. Start with a conservative set up and change one thing at at time while recording the results. Don't forget air and track temps, use a spreadsheet for gathering data including shock settings, spring rates, camber, caster toe, height and sway bars. You should also know your corner weights and adjust with fuel and passenger as necessary. It's very satisfying to understand how your set up changes affect handling.

Be careful not to under inflate those R6's or you can ruin them in a single session. If it's cold, (40-50) you may need to start in the 33 to 35psi range. This is where data recording helps. The R6's are faster in 40psi range but are more of a handful to drive.

M758

Yes, but for many of tires are the biggest track expense we have. Moving up from a cheaper slower car to faster more powerfull one may not seem that expensive, but you NEED to consider the tire impact. It is easy to double your per event operating costs just by adding some HP and stickier tires. We are all free to chose to drive what we want, but realize the cost impact. Z-man's 944S2 is in the moddle of power difference between you RSA and my little 2.5L car. It stands to reason he would get more life that your RSA, but probably less than our 2600lbs 135 whp 944-spec. Even so we push 100% all the time as we are racing. In DE you can probably get a little more life just by running 90%.

What can say for certain is that I have a 944 Turbo S sitting my garage. There are times I considered tracking that. However it is the tire bill that gets me every time. I can probably see the 944 spec and take that money to prep turbo to a decient level. However I think the tire bil would kill me after year or two especially if I wanted race it with hoosiers.

M758

I am will Larry on this.. The car will toe out underbraking. Now depeding on how you set-up the rest of the car this toe out can be inconsequential or create massive issues. The fact remains that it will toe out. The best way to compenstate is to go all steel in the bushings and have strong LSD for braking stablilty. The problem is if you make too many suspension change to compensate you are going to hurt the car in other places on the track.

So you can run zero rear toe and have the car stable under brakes, but I am sure it make it crappy other places. The fastest cars will have some rear toe in so they can be balanced other places. The key to minimize that as much as possible and keep the balance elsewhere.

M758

Tire temps are the best way to understand your camber needs.
Anything you hear on the net can only get you close. You really need to take tire temps to really understand how the tire is working on your car. Some guys push harder than others and have different spring rates. Plus some guys may perfer to give up a little performance in one area to get it back someplace else. Given their driving style it may prove faster for them. Or they could just be simply wrong and they would be faster with your settings.

SamGrant951

You must be going for the DE championship

I dont think I could justify the cost unless I was racing (or I was getting them used/cheap with a few heat cycles) Good luck though, let us know how it goes and how long they last!

944CS

Judging by the ride heights I see in 944 spec and cup, you are correct, the car will toe out under braking. However, it is not correct to make a blanket statement that reads "a semi trailing arm suspension will toe out under braking and toe in under acceleration."

Just for reference, here is a daily driven n/a 944 with full interior and the a/c on. The suspension is not set up like 944 spec/cup, he is very comfortable in the car, and it around 2 seconds faster from turn in at 1 to the bridge at summit point (in 2007) than the 944 spec guys were in 2007. He is on RA-1's as well, 225/50's.

http://www.youtube.com/watch?v=Xo-V1lwXuZY

and the 944 Cup video I used for reference
http://www.youtube.com/watch?v=ARro9ekEcJs

Z-man

To get back on track (pun intended) --

Any thoughts on the BFG-R1's for the same application? My understanding is that these shoes are less grippy than the Hoosier's, more grippy than the Toyo RA-1's, and about as durable as the Toyo's.

Should I go with those instead?

Thanks,
-Z-man.

Z-man

OK - spent a day at Monticello Motorsports Club yesterday running on Hoosier R6's for the first time. Ran with a new club - Trackacardia - in their instructor group. This was my second time at Monticello.

My initial thoughts --- HOLY @#$^$!!!! These things can GRIP GRIP GRIP!!! As I got more confident with the tires I was able to carry significantly more speed through the corners -- these tires just stick like crazy!

I have tried the dark side, and I like it!

-Z

Larry Herman

Dave in Chicago

Sorry old friend... but you just took a hit from the crack pipe. Say hello to the new monkey on your back. He will require regular feeding of about $1200 per set.

Resistance is futile.