I have a test and tune day tomorrow at Summit Point. My car handles fine but I get wheel hop and loose rear if I try to power out of a corner fast or early. I am not sure there is any oversteer but certainly no understeer. So I thought I would make small adjustments to the rear sway bar & or JRZ triple adjustable remotes. I have all the notes on what adjustment affects what but the question is: On the top of my JRZ remote is a dial +/-. Is + stiffer or softer as in += more travel? 2nd question is will adding a touch of understeer add to the rear end grip?

 

Bill,
The "-" will equal less rebound or compression.

My car was handling in a similar way and I decreased the compression by three or four clicks (previously it was equal to rebound) and that helped a bunch.

This is a quote from the Penske guide to Damper tuning.

" Compression: The idea is to set the compression damping forces to suit the bumps in critical areas such as corners and corner exits. Increasing or lowering cannister pressures can have an influence on support under braking, acceleration and tire loading on turn in and mid corner grip.

Step 1: Set the rebound adjuster at full soft
Step 2: Starting with the compression setting at full soft, drive a lap then return to increase the bump (compression) settings. Continue this process of adding bumpcontrol to minimize the upsets until the car becomes harsh, loses tire compliance and traction. At this point you know that you have gone too far on the compression settings, back off one click.

Rebound:
The idea is to tighten up the car, stabilize the platform and eliminate the floating "Cadillac feeling". This will also reduce the rate of body roll.

Step 1 With the rebound setting at full soft, add 5 clicks of rebound adjustment (I think the Penskes have a lot more adjustment so maybe make this number a bit less, 3 perhaps) at a time, then return to continue the process until the car become "skittish" or the rear wheels hop under braking. At this point you have gone too far on the rebound setting, back off one click at a time for final balance."

http://www.penskeshocks.com/Adjustab...h%20Manual.pdf

 

Thanks Greg!

When you decreased the compression by 3 or 4 clicks was that in the front only? Stiffen the front with (-) compression?

 

Bill,
I did that on all four corners because the car was not very compliant in the turns and it was hard to get the power down.

The rebound (setting on the shock) stayed the same but in general I run the front about three clicks softer than the rear.

Turning towards (- ) will soften the settings. To the right is decreasing/softer (-) and to the left is increasing/stiffer (+)

Does this make any sense?

 

Got it. I will play with it tomorrow and try your settings. One last question. My rear big fat sway bar is in the stiffest setting (bolt hole farthest out/extended) should I soften it to the center?

 

Bill,
That might help as long as it doesn't make the car push by softening it too much.

What kind of differential do you have? The issue could be there too.

 

we added the limited slip last fall or winter. I think it is a GT product but not sure.

 

Bill,
Just so we are clear. To stiffen the rear sway bar you make it shorter (bolt holes towards the center) to soften it you move then towards the end and lengthen the bar.

Sounds like your bar is already at the softest point.

 

You are right. I am in the outside hole, full soft. Good thing we had this conversation. I would think my engineering crew would handle all this fine tuning... its hell to be poor.

 

Or you need a simpler car! Three way adjustable shocks indeed. It's all I can do to remember my general tire pressures and how much fuel did I use last time out...

See you at the track this weekend! Forecast keeps changing, was showers both days now just Sat.

Brandon
911-dead-nuts-simple-SC #77 (#177, actually for SP this wkend)

 

Bill,

I know the 996 likes the bars set full stiff in front and full soft in the rear. Not sure if this applies to the 993 but you may want to give it a try.

Karl

 

No...it does not like it... too much understeer!!! Trust me!!!LOL

 

Danny,
In general you are probably correct but some of it depends on which sway bars you have. There is a RS bar and a GT2 bar for the 993.