Wagging tail at top end...

[SITHV6]

For the past few times I was both at the track and out in the woods G-Teching my Brick...at the top end of the runs about 100+mph the rear end would wag a good 3-4 inches from left to right ...are my Axles or bearings worn out? I have an Auburn rear end with stock 3.42s and air bags.

 

[Tony Shoaff]

Tire psi is to low? What tire and psi are you running?

 

[leprcon]

its the g-body wobbles its pretty scary i put a h & r bar on it and it fixed everything. it will especially help if you dont have a front swaybar

 

[QUIP'6']

i second the tires and psi. i ran 10 psi in slicks and it swayed back and forth on the top

 

[LBNJWE4]

i second the tires and psi. i ran 10 psi in slicks and it swayed back and forth on the top

+1, I had that with slicks at about 12psi, never had that problem with stock tires or drag radials

 

[gbsean]

check tire pressure...make sure they are equal...have had that happen with too low pressure....

 

[QUIP'6']

when you are purchasing slicks you have to get the right compound for the sidewalls a slick for a light race car maybe for 1800 pounds and a d-6 compound and a d-3 compound is for 3000+ pound cars.

 

[GN87Mike]

Years ago I ran BFG radial T/A's and had the same thing you describe in 3rd gear. This seamed to get worse as the car went faster into the 11's. When I would change to slicks for the track the car was always straight with no hint of the back and forth wobble and no other change than the tires. I thought it was the belts in the tires causing it. I now run MT Radials and MT slicks and do not have any wobble so for me it was the street tires. - Mike

 

[Chuck Leeper]

Improper/insufficient caster.
Wheels too narrow for the slick width.
Air bags screw w/ the action of the shocks and springs.
@140+, mine did the same thing.
[We changed to the HR bar, and dumped the bags.]

The cure:
We video'd the car at 1000', and at 1320', to see what tire to fender lip separation we had. Was right at 2". [850FWHP helped!]
Check alignment w/ car at race wt, and you in the seat. Print it out. Raise the ft end 1", repeat.
Raise it 2", repeat.
Raise it3", repeat.
When you look at the raised position results, you'll likely find the caster has gone to zero, or worse.
I had the tech set the alignment w/ the car raised 2".
Drove like it was on a rail....

 

[chris mccord]

Mine did this on street tires on a top end run....scared the crap out of me at 100 or so.

 

[kenny]

Could be worn out trailing arm bushings as well.

 

[d90dan]

Had the same problem running M&H drag radials. Anything over about 125mph the rear end would dance on me. 325/60/15 on 8" wheels. Tried 10" wheels and had the same problem. Put on some quick time pro's and problem solved.

 

[turbofabricator]

I find it REAL noticable after 130mph and after a couple of Long Island Ice Tea's.........upped the Iced teas to 6 and ALL wobbling went away, but MAN did my head hurt afterward.:biggrin:

Listen to Grumpy........."sometimes" he comes up with some good stuff.






No, I really don't drink and drive.

 

[mscalc]

I had a buddy years ago that had a built 383 in a Monte Carlo that would do what you are describing. His was the bushings in the rear arms. My GN would do this at lower speeds with the 10 yr old BFG's on it. New tires a couple yrs ago cured mine. I would start with checking the rear suspension though.

 

[brian]

One of my old T-Types did this.
My problem was where the SSM low control arms bolted to the frame.... The frame mounts were cracked on both sides. A little welding and I was good to go.

 

[SITHV6]

Gonna start with the Basics...

*Slaps own forehead since no-one eles is around to help do it* :redface:
Went out into the garage and lo and behold the car was STILL at Test n' tune specs before the rebuild...in my enthusiasm to see what improvements were made from the cam and turbo swap i had completely forgotten to check the tires! :tongue: Tires were at 18lbs and 13lbs with no air in the bags at all!! Guess that would explain the wagging eh?
Gonna refill the bags and tires to proper pressure and try it again prolly later tomorrow and see what happens. kinda feel silly now coming home with a brand new set of MT ET Street Radials thinking it was a quick fix! Thanks again to all whos shared their thoughts and horros of the Wiggles!

 

[Chuck Leeper]

"Gonna refill the bags"...
You have 2 bags? Are they on a single fill line?

 

[SITHV6]

nope! each bag has its own line with tappet drilled into the trunk. so right side bag can have more air than other or if i have a heavier friend than usual riding with us and need BOTH bags filled.

 

[SITHV6]

Well...Wiggles are gone! thats all it was...too low Air pressure in tires! CANT WAIT to get to the track now!!

 

[hrhoward]

Sphincter tightening none the less, eh?