Traction and Suspension Tuning Help
 

Hey Guys - request help with traction and suspension tuning with 72 GTO.

Car launches straight, carries the wheels But now has a traction issue.

New best with a 6.41 at 105.5 and later spun at 106.

That was an improvement of over 4 mph when I ran a 6.58 at 101.8 from a carb tune, slight port match and a change from 3.73's to 4.11.

Still launching at 3,500 - 2-step with 5,000 still to grab.
Turbo 400 4.11 Pro gears with MT 10.5w x 28 slicks

Front suspension:
QA1 Pro Coil Double Adjustable GM coil over conversion system with 350 # springs
Adjusted to 90/10 settings
Low friction control arm bushings and ball joints
Front end limiters set to no limiting
Total Race Weight 3440
Front weight 1860
Rear weight 1580
Percentage Basis Front to rear 55% to 45%

Rear suspension:
Full length Competition engineering adjustable ladder bars
Bottom hole lowest front heim end setting
Right bar - slight preload
“5 #150 (?) lbs - springs with spring jacks
28 year old Koni single adjustable set at 1 turn tight from lightest setting=Issue(?)
Pinion angle 2 degrees negative
MT 10.5w x 28 slicks with tubes at 14 pds cold - best runs

Thanks Guys, Craig

I haven’t had to do any tuning in a long time my car, just about hooks in gravel, but when I first put it together I found I had to tie the front end travel down. Which was very much the opposite of my slapper bar car which liked a lot of unimpeded front end travel.
I also found w my slapper bar car that video of the launch was needed to be able to tune the launch. Even just for tire pressures I really needed hood video of how hard I was hitting the tire. This was even more important when I was running stick cars.

Sorry probably not much help.

I would try a couple clicks in the rear shock maybe 3 and more negative
pinion angel. To make a real hard hit off the line move L-bar up one hole
iIn the front.I would try the first two sugestions first.

GT

Probably useful to consider what the tires are telling you before changing suspension settings.

Hard, very smooth surface....might need a softer compound.
Slight almost imperceptible fuzz....about right on compound
Rolled up bits of rubber like old sweater fuzz or like little worms...too soft.

Starting line pix and video of the sidewalls....nice wrinkle or getting totally wadded up...might need more pressure if so.

Wear pattern across the tread.....should be fairly even over the majority of the tread if tire pressure is close.

Discuss with an MT expert (not me) how much burnout heat they need.

FWIW,
Eric

All good info - I was thinking that the old Konis should go - what about strange double adjustables?

Thanks - how to get set up with video - equipment - on the car location - video shot from helper?
Budget please.
Thanks, Craig

double adjustable can be your friend

Have someone video your car when launching. It will tell you everything you need to know.

Front suspension I would start at 2 clicks from full tight on compression and set rebound so that the front shocks are fully extended at about 1 second into the pass.

Rear shocks have to be loose at only one click. Unless they are valved super tight. I've had good luck with single adjustable shocks, as long as they are in good working condition. But double adjustable shocks are definitely a big improvement.

Hey thanks guys I really appreciate all your good input.

I think the next step is to follow through with many suggestions and is to be able to individually scale all four wheels, invest in a good pair of double adjustable rear shocks and look at springs and height adjustments – of course getting a good video to review and share.

Any other ideas are also greatly appreciated.

Thanks, Craig

Agree with having someone video your launch.
Used to be able to record so one could have super slow motion on video.
But that was with old VCR video camera.

Strange you carry wheels and still spin or traction issue?

I'd try raising bar to middle hole.
Why I asked in other thread is if the 'holes' are not in a good position you may never get a good setting? (either to low or too high, no good setting)

Do you have a spool?

:confused:

spool yes and carries the wheels on the one good pass.