[Shotimes] Re: Handling & tuning recommendations

[Leigh Smith]

van Oss wrote:
 > My friend Alan Fanning has sent me a set of DELRIN bushings for the 
26mm rear sway-bar.  Not gonna deflect much.  I didn't even know
 > such things existed.
 >
 > -- 92 SHO, highly modded, used for track days on road courses, 20/26, 
Tokicos, SHO Shop linear front springs, Eibach rears, race
 > tires, subframe connectors, STBs, etc.
 >
 > -- 91 SHOable, lightly modded, used for winter driving, ice races, 
and SCCA Solo II, 24/26, Tokicos, Eibachs front, Cargo Coil rear,
 > all-season tires in winter, race tires in Solo II.
 >
 > Joseph van Oss

Joseph;

Is the 92 used for street use or pretty much dedicated to track use? It 
makes a big difference in how far to push the lack of compliance issue. 
On a race car you want none, except suspension movement. On a street 
car, you need some, and you can definately go too far.

For track use First: get rid of all the rubber. Put delrin anywhere you 
can get it, poly everywhere else. Especially lower front & rear control 
arms. Delrin deflects less but will rattle more, but in a race car who 
cares? I run it on my track car, which is ocassionally street driven, 
and it is a rattle-box. It has heim-jointed sway bars, etc. but it is 
very predictable at 10-11/10ths on the track. Second: Rebalance the 
steady state handling with sway bar adjustments as necessary, with race 
rubber installed. Third: Fine tune sway bars for corner entry and power 
on balance preference. I would make the rear one adjustable somehow. 
Forth: Then tune the adjustable shocks to smooth corner entry / exit / 
turn-in.

For the street: Stay with the poly bushings, you'll be happier unless 
you like rattles. Even leave some rubber or soft poly in less handling 
critical spots for tar strip compliance / defelction. Aka: the front 
side of the lower front strut brake reaction rod. The rear side is hard 
poly (stock) on my 89, good for power-on torque steer control. I would 
even consider a front poly bushing for the lower front control arm for 
the street, but I don't know if such an animal exists. That joint is 
highly loaded in turns but not on bumps. All poly in the rear still 
leaves you some deflection if you leave rubber in the brake rod again. 
On sway bars I would go all poly on the street, for rattle reasons. 
Especially Kill the rubber subframe bushings too.

In either case, make sure you don't put too much rear oversteer in it 
with that sway bar combo. Make sure it stays stuck, with a little bit of 
steering (10-15%), and then hard on the brakes at 90-95% braking. 
Without doing the Porsche 911 rearend-swap dance.

Have fun!

My .02
Leigh


> _______________________________________________
> Shotimes mailing list
> Shotimes@autox.team.net
> http://www.team.net/mailman/listinfo/shotimes
> 
> .