Bagnall928

Greg Brown said in another post that “ 928’s understeer came from the factory “
i’d like to pinpoint exactly how that was built into them. I suspect it has to do with roll center location and center of gravity, height, weight transfer, and the rate of the transfer.
Stiffer springs, stiffer bars, and bushings quicken the weight transfer to the loaded tire. It’s possible to ask too much too quickly from a tire that’s loaded to the limit. We’ve all heard, squeeze the break, squeeze the throttle, and have light hands on turning.All have to do with speed of weight transfer.
Is the argument for maintaining the rubber bushings is that their progressive nature slows the loading to the outside tire?
David Vizard( the engine guru) raced Mini’s when he was younger. he maintained the rubber brake( they expand) lines to help modulate the application of his brakes. maybe rubber drop links on the sway bar may help reduce understeer?
the question I’m trying to find an answer to is how to pair bushings, bars and springs on the 928
How to give the car what it wants!

icsamerica

Listen to Mark and others who actually have recent seat time and can prove it. Ignore the noise of others that may have their perspectives influanced by self aggrandizement and profits.

Bottom line, setup the car as good can you can and learn it. I've seen an 80 year old Instructor in a Honda Accord sport and a Retired Pro in a Ford Contour sport drive around other far more capable cars on the track. Seat time is important. For me sim racing gets me the seat time I need to learn the track and it's nuances before I get there.

Darklands

Aside from your personal dislike of Greg and the concomitant disparagement of his company, I would seek advice from people who have the resources to try out many different setups and also offer them as a kit.

What's wrong with making money with it?

You also get a benefit! Experimenting can be much more expensive!

puyi

If you are to stiffen swaybar, just remember that you need more grip from the rubber. It is the way, anderson and kibort say it. They have (had) large rubber. On my own, a '89 gt, i run with 10" wheel and 11" rubber and the grip is sufficent for original sway bar. But for sure, all that depends on the track record you want to check. Anderson was to suprass 996 cup! and it seems that kibort was on the way to be @ 993 cup level.

Crumpler

https://www.elephantracing.com/tech-...eer-oversteer/

Handy cheat sheet I use.

Bagnall928

Thanks again to everyone. Your comments are much appreciated.
I race in the SCCA. The classes that the 928 can run in have wheel,weight and engine rules that will determine my approach.
Im leaning towards historic racing that is a little less competitive and somewhat showcase.I want to build a good representative tribute to 928 that’s fun to race.It probably won’t have a big motor or big rubber. Light as possible,Euro S power ,9” wheels and a complimentary suspension that handles!
im trying to determine what combination of suspension components will get me within tuning range of that….out of the box.As close as possible anyway!
Thanks to everyone that’s shared their trial and error results.Its very useful!

GUMBALL

.
Also, recommend reading the Carroll Smith books:
- Prepare to Win
- Tune to Win
- Engineer to Win

Some of the info is not relevant to your car, but, good reading anyway. Also, on the subject, another of his books is Drive to Win.
.

Bagnall928

Thanks Gumbal
great books
I have all 4

hacker-pschorr

I'd look into NASA over SCCA and look at Super Touring classes. It's been a while since I've been involved with these groups (used be work for a 3 car Vette ST2 team).

IMO this is the best idea as I've been involved in various aspects of vintage racing since I was a kid. Running with a smaller group a 928 would fit nicely in Group 6, historic SCCA Trans-Am. At Elkhart Lake the spread of lap times can be anywhere from mid 2:20's into the 2:40's and most every track prepared 928 I've seen run there is in the lower 2:30's or faster. You'll be with cars of a similar size, weight etc.... There are 3 vintage events at Elkhart Lake every year and the spring event is the most lax when it comes to car classes. I've seen everything from a factory prepped Lotus Esprit Turbo to modern Mustangs and the occasional Japanese race car with Group 6. The core of the class are vintage pony cars, random 911's (from small displacement lightweights to bonafide RSR's) and the occasional Shelby Cobra.
I'd contact SVRA and VSCDA, especially if there is a local chapter, and see where they would slot you in. With vintage racing, again, depends on the prestige of the event, rules get very gray. When you see a 400ci small block from a sprint car in a 1967 Corvette racing in a "historic" group, you just have to chuckle (such an engine puts out like 800-900hp).

If you run with a historic group that won't allow anything outside of the vintage definition of that class, you could end up in some kind of exhibition group. One year at RA that group has a pair of 962's, pair of R8 Audi's, and a couple 993 cup cars, with everything you can imagine in-between. The downside to that class is you may not have anyone to run with and you'll never be able to stop watching your mirrors.

icsamerica

One of the Events I do every year is the Empire Cup, a VSCCA event in Early June at Limerock. It's a full unmuffled 2 day event with full camping and it's awesome. The cars are amazing with many in the mid to low 50's which is a time I seldom see at other LRP events with far more modern cars. The VSCCA guys, in my experience, are a great bunch on and off the track.

Bagnall928

Iscamerica,
what car group do you run at that event? How many times on track?

icsamerica

My time at LRP in this field puts me in the Novice group. Over two days 7 to 8 sessions.