5th Coil Location ?

[RACR_73s]

When I set the car up at the first of the year I did not understand what GRT ment by 36" c/c on the setup sheet. I forgot to ask Joe when I talked to him for final setup ?'s what it ment so I just left it where it was. By reading some other post I figured out that what I think it means is center of rear end to center of shock mount...correct? Mine is set at 32" c/c with 2 rounds of preload and would like to know what it would do to change it to 36"? My car is an 05 GRT w/ floating X and is one of the fastest cars in my division(Limited lates) and I am usually able to race into the open shows. With that being said, I am a little hesitent of changing too much but if it would help get it to be better, I would try moving it. ~Thanks~

[dchamp3]

If you but it at 36'' the traction will last longer down the straight away,it is good when the track is slick, what size track do you run? and is it wet or dry .

[FlatTire]

When its tacky and the car is a little tight getting out and wont stay on the bottom I will move the 5th coil back. When the track slicks off and it wants to tail out from the middle out
I'll move it forward and correct some of that.

[MasterSbilt_Racer]

I guess a simple way to put it is the car "acts" like it has more rear percent as you move it out (as far as exit handling goes).

[RACR_73s]

Track is 1/4 mile with decent banking and slick after hot laps most nights. Car is good in both but have had trouble hooking in the real dry coming out. Only changes are the left and right bottom bar down as night goes on, take some stagger out and shock adjustment according to GRT site. I was getting ready to try more left and rear in the slick also...is that in the right direction? Might see if this helps also. Thanks for the replies.

[dchamp3]

I would move it out to 34'' and try it,what rear % do you run? like to see your whole setup just to see what you got makes it easier when you know everything.

[RACR_73s]

Info for 2007 and previous year models:
RIDE HEIGHTS��(CHASSIS #2938 and before, Standard Front End, Black Spindles)
LF: 3�� Top of Lower Control Arm & Bottom of Frame (2.5�� on cars with gray spindles)
RF: 3" Top of Lower Control Arm & Bottom of Frame (2.75�� on cars with gray spindles)
LR: Will be set with the amount of bite
RR: 4.25�� Top of lower under slung & Bottom of Axle Tubes

STANDARD SPRINGS
LF: 550 RF: 350
LR Behind: 250 RR: 225

SHOCKS (MY #'s) SLICK TRACKS
LF: 75 RF: 75 LF: 5-3 RF: 3-5
LR: 7-2 STD RR: 94 LR: 7-2 RR: 3-4
Oil double adjustable afcos

BITE
130 LBS LEFT SIDE 54.7% REAR 55.4% (MY %'s)

TORQUE ARM
73-6 Shock with 325 pound spring and 75# gas
Approximately 3�� travel on 36�� center to center(Don't know the travel and mine is 32 c/c)

REAR END LEAD
Right rear back 1/4�� to 3/8��(Mine is straight up)

FRONT END ALIGNMENT:
CASTER: CAMBER:
LF: 1.5+ LF: 2.5+
RF: 3+ RF: 3.5-
Toe: 1/4 to 1/2 out

NEW STYLE PANHARD BAR BRACKET
�� Bottom of Frame to Bottom of Bracket (8 3/8��)
�� 3rd Notch up on chassis, 2nd notch up on pinion
�� Panhard bar: 19 1/4�� center to center

4-BARS (STANDARD)
Left Lower: 3rd Hole up (6 to 7 Degrees)
Left Upper: 7th Hole up (23 to 25 Degrees)
Right Lower: 4th Hole up (Level)
Right Upper: 5th Hole up (18 to 20 Degrees) chain set to max at 44 Degrees to keep lf down

This is as close to GRT setup as I can get with what I have to work with as far as shocks.
Car weights 2450# and must run on LM40 Hoosiers and has steel block 550-600hp

[dchamp3]

Have you ever tried it at 34'' or 36'' on the 5th coil with the same spring? if not you need to it will help on the staightaway and have you ever ran a 200 lr that will help also a softer lr will give more traction than that 250 lr. we always run a 200 lr 225 or 250 rr.

[RACR_73s]

Have you ever tried it at 34'' or 36'' on the 5th coil with the same spring? if not you need to it will help on the staightaway and have you ever ran a 200 lr that will help also a softer lr will give more traction than that 250 lr. we always run a 200 lr 225 or 250 rr.

No I have not moved the 5th coil? I do not feel that I need more traction further down the staright(I dont feel the traction giving up). When do you run the softer LR...early/late in the night? What will it do to the car? According to GRT setup it will tighten entry and loosen off...which would be opposite of what I would want off late in the night or early for that matter. ~Thanks~

[MasterSbilt_Racer]

No I have not moved the 5th coil? I do not feel that I need more traction further down the staright(I dont feel the traction giving up). When do you run the softer LR...early/late in the night? What will it do to the car? According to GRT setup it will tighten entry and loosen off...which would be opposite of what I would want off late in the night or early for that matter. ~Thanks~

Those setup sheets are never correct for all tracks and driving styles. The GRT setup sheet is correct for a track/driver combo where your car gets off the bars at some point after corner entry and before you pick the throttle back up.

Moving the 5th coil out gives you more forward traction at the expense of effectiveness of the front end to steer the car. More instant traction or traction further down straight has much more to do with the 5th coil rate than location. This is often blurred and confused since you need to soften the rate when moving the coil forward to maintain a similar amount of travel. Think about it, you get more movement of the 5th arm for a given amount of axle rotation as you move farther from the axle centerline.

[dualdj1]

just curious if a different length of 5th coil spring has any effect? like 12" vs 14"? wouldn't think so (or not much at any rate), but was looking at a different spring possibly, and have both options with our setup.

(Not trying to hijack your post Scott, though it may be relevant to you as well)

[MasterSbilt_Racer]

just curious if a different length of 5th coil spring has any effect? like 12" vs 14"? wouldn't think so (or not much at any rate), but was looking at a different spring possibly, and have both options with our setup.

(Not trying to hijack your post Scott, though it may be relevant to you as well)

No effect as long as you don't coil bind.

[dualdj1]

How about preload? What effect does more/less preload have on 5th coil? Pierce suggests preloading the 5th coil more vs going softer. That seems backwards to me?

[RACR_73s]

Those setup sheets are never correct for all tracks and driving styles. The GRT setup sheet is correct for a track/driver combo where your car gets off the bars at some point after corner entry and before you pick the throttle back up.

Moving the 5th coil out gives you more forward traction at the expense of effectiveness of the front end to steer the car. More instant traction or traction further down straight has much more to do with the 5th coil rate than location. This is often blurred and confused since you need to soften the rate when moving the coil forward to maintain a similar amount of travel. Think about it, you get more movement of the 5th arm for a given amount of axle rotation as you move farther from the axle centerline.

MBR, is there a certain amount of spring rate you need to take out as you move the shock forward? Do you also need to change the shock rates as you move towards the front of the car? Thank you for you input.

[MasterSbilt_Racer]

MBR, is there a certain amount of spring rate you need to take out as you move the shock forward? Do you also need to change the shock rates as you move towards the front of the car? Thank you for you input.

I would just move it forward if you are attempting to gain traction. People improve their cars on slicker conditions by sometimes doing opposite adjustments. Data acquisition would be necessary to get the "correct" answer.