Mike Simard

James, I've run my stock 87 back to back with street tires and Hoosier R6 dumster tires (on 8" S4 rims). Ooh, it's so nice to have sticky tires
The main thing I remember was the back of the car wouldn't budge, I couldn't get it to rotate by sliding the rear. It was still very quick and easy to drive. that was with about 1 degree camber F&R and 30psi cold.

The next track day (TGP) in this setup is this week so I'll try some things.
Since it could use less understeer I'm not going to do anything to the front bar yet. I'll crank in some more camber, set zero toe F&R, see if it had lots of toe in at the rear because I've never checked it. The only suspension mod this time will be a rear upper control arms with Spherical bearings. I'll mull over this thread for setup ideas and report back this Friday.

123quattro has a good point about the front toe. I don't know what kind of Ackerman(sp?) the 928 has but looking at the steering arm, it looks like not much. That would make the car respond well to some front toe out on a tight course.

James-man

Ooooo, good comments & suggestions! Thanks guys!

I found an IR laser thermometer: $30 at harbor freight. I could probably borrow one from a buddy at the track as well. So do I log several sets of temps, then back to the alignment shop to guestimate the changes needed. There outta be mobile alignment shops at the track.

I may actually become fast one of these days!

Jim bailey - 928 International

You will never go back !!!! they do like 2-2.5 negative on the front and most work best at fairly low tire pressures....I use Kuhmos they are inexpensive seem to work pretty well and last several hours...plus I drive on them to the track...and carry a second mounted set in the car. Get them shaved and heat cycled it really helps with the long term performance.

James-man

Yep - Prolly not!

I look forward to a new learning curve. Funny thing: I am a national PCA instructor, but have only enjoyed sticky tires while SOMEONE ELSE was driving. Seems important for me to have personal experience with these types of tires if I am to be coaching people with them. Thus far, I have only needed to focus on teaching lines, awareness and smooth inputs, which I suppose has been fortunate.

I am generally a safe, aware driver. Should I bring another instructor with me as I experiment with different tires' capabilities? Any thoughts?

Thanks.

Jim bailey - 928 International

Test the limits in slow corners with lots of runoff You will be fine !

atb

James,

You're going to like the R compound tires, it'll be hard to go back to street tires later.

1) They don't howl at the limit, they just scuff and breakaway. Be ready.
2) Cold, they are going to feel worthless, because they aren't going to stick and will be underinflated. I started at 29psi cold w/stock rims and tire sizes. If you don't have a lot of time your session, you may want to start with more pressure. Stay with it and get them heated up.
3) Once up to operating temperature, and this is speaking just from my own experience with the Kumho Victoracers, they still never feel as good as a street tire going down the straights (a little cobby-feeling), but in the corners they grip like crazy. If you shoot for 36 psi hot I think you will find yourself in a good middle ground, and then can add or subtract air from there.
4) Watch, and experiment with your pressures. I've heard some crazy things around the pits about pressures. Some running in the 20's hot (944) (I don't know how they keep the tires on the car) and some running in the upper 40's (BMW). It would be interesting for the racers to pipe in about what pressures they run.

A lot of guys are posting about more aggressive alignment, but you'll be fine with stock. I was still able to get farily uniform temps across my tires (again stock sizes) with stock alignment. Probably wouldn't be the case with wider/taller tires.

Have fun, good luck!

cdbtx

LOL - I was running 24 in front and 28 in the rears on the Pilot Sports.

I spent alot of time checking temps, checking wear, adjusting temps.. then I changed tires and tire sizes so it's back to square one..

I'm running 30 on the Toyo'

Those are cold temps plus cool track temps in Seattle.

James-man

atb: Good input! The lowest I've run hot on street tires was mid-30s. Keep in mind that i have the 50 profile stock sized tires so they get pretty vague feeling at lower pressures. The taller the tire, the more the sidewall flexes. I have noticed that cornering is best if kept below 40psi. We usually have pretty high ambient temperatures here.

I'll shoot for mid 30s psi on the Rs.

Chuck - how light is your car? I am surprised that people run THAT low!

atb

Well, at least you were close on the rears...

24 in the front? Could you hear the rim beads scraping the pavement on that first sweeper?

I forgot about our cooler climates up here. I wonder if it makes a difference once the tires are up to temp, or if once they're hot, they're hot.
Guess you'll find out next month huh Chuck?

cdbtx

Actually Adam - when I ran on a hot day, ok hot for Seattle - low 80's and at Pacific Raceways my tire temps were about 40 degrees hotter than a normal day. Also my tire pressure increased by 12lbs.

Which reminds me... always log my settings and the enviromental stats. I'm getting too old to remember those things...

It's funny, but my car performed the best at 24lbs in the front. I think that setting the tire pressure correctly takes alot of experience and skill, something that I hope I'll have someday..

Black Sea RD

You should add beefing up the sway bar body mounts in your list of things to do. The forces that you will be generating with good R compound tires will increase the loads seen by them greatly and they will rip out over time. Having done this to my 1986.5 track car as a precaution and seeing the way Porsche welded them to the body, I saw why.

Excuse if this was already covered,
Constantine

James-man

Constantine,

I haven't heard this before. Was only planning on upgrading swaybars next year. I'll have my shop look into that for me - they do racing fabrication work for other customers so I would imagine that this is up their alley. Thanks

Black Sea RD

Hi James,

This is in regards to the front sway bar mounts.

Good luck and have fun,
Constantine

Mike Simard

Well, I just got back from a day of track testing tire pressures and alignment settings on a stock 87 with used Hoosiers. I did find some good settings/pressures but you could run the stock settings and be fine. My pressures were 42 fear, 44 front hot. That's very hot actually, measured within seconds of hard driving and about 10 psi more than if cold.

BTW, some random comments at the track:

911 driver: "your car sounds like a Nascar coming down the straight"

Young Mustang dude: "did you put the v8 in yourself?"

SwayBar

Those pressure are pretty high, hot, for Hoosiers; we typically run 38-ish hot front and rear.

I've said it before, but the best sounding car EVER at Road America is Jean-Louis and Agnes' 16v Euro which has MSD headers, a Y into a 3 or 3.5 single pipe into a straight-thru Magnaflow (..I think). That car sounds like a racecar should. It has a higher pitch (..not rumbley at all), while being very harmonically rich. People come up in the pits and comment on it's sound all the time.

Now that I'm thinking of it, it reminds me of the Indy cars at the Brickyard during the mid to late 70's when we'd skip highschool to watch testing and qualifying.

What's up with those 16v's sounding so good? The 32v's are close, but not close enough for whatever reason.