[GTO2nv]

I have a 482cubic inch 3500lbs. car launch at 3000rpm and it just spins leaving the line. I have 3-way adjustable shocks,moroso trick springs,an air bag in the right rear with 15lbs. and south side machine bars,oh and the slick is a hoosier 29x11x15 what else can I do?

[71 Ventura II]

Originally Posted by GTO2nv

I have a 482cubic inch 3500lbs. car launch at 3000rpm and it just spins leaving the line. I have 3-way adjustable shocks,moroso trick springs,an air bag in the right rear with 15lbs. and south side machine bars,oh and the slick is a hoosier 29x11x15 what else can I do?

1. What gear are you running?

2. What differential? posi or spool?

3.. Isn't a 482 cid a bbc?

[Ron H]

.100 over 455 4.25 bore and stroke.

Is it spinning at the hit or hooking then spinning?

Have you tried the different settings in the shocks?

What are they set at now?

[cutrone]

How old are your slicks & how many runs on them ?

[Craig Hendrickson]

I'm not familiar with "South Side Machine" bars for A-body. Are they like the Edelbrock 5213 Anti-hop Bars? If not, then install the Anti-hop bars. They will hit the tire harder off the line.

[Jagtec1]

Have you tried leaving just off idle? I would leave anywhere from 1200 to 2000rpm, and it worked well.

[Cliff R]

What car?

Rims?

Offset?

Tire pressure(s)?

A bit more information would help?

What are the 60' times, ET and MPH?

Also, what tracks are you testing on? I live about 40 minutes out of Columbus, and there are a couple of tracks in this area where good traction can be elusive......Cliff

[Michael G]

This post kind of caught my eye.
Not knowing your setup, I would guess that with an 11 x 29 tire on an A body you've got the rear suspension set up pretty stiff so the tire doesn't hit the wheel well on launch. My opinion, air bags are for the tow vehicle.
A nice sway or anti roll bar with a looser rear suspension to let the weight transfer works very well into the low 10s, even with a 9" tire.
I will be interested to see where this post goes.
Good luck

[GTO2nv]

The car is a 71 GTO Front suspension 90/10 shocks and mororso trick springs and tubular upper control arms and stock lower arms. The rear is a 12 bolt with a richmond spool,4.11 gear.The right rear shock is set at 50/50 and the left shock is set a 30/70. I have moroso trick rear springs where the right spring is stiffer and an air bag now to make the car launch straight.The south side machine bars take place of the lower control arm and they are a lift bar.I am afraid that the car needs to be back halfed to fix this problem!? We went to mt vernon yesterday and the car did really well in the mornoing but when the track temp got to 127 degrees thats when it went bad for me.On the average the car would 60ft between 1.42 to 1.45 after I installed the air bag The car went 1.40,I thought that was really good for how hot it was yesterday,but when the track temp got to 127 the car went 1.49 WTF?I need help!

[Ron H]

Is it spinning off the hit or a few feet out?

Are the front shocks adjustable?

Hot tracks always cause issues.

You need to soften up the rear shocks for a slcik track. Tighten for a tight track.

Perhaps having some ballast in the track will fix your problem. It will slow you down but it can help you hook on a bad track.

You can also lower your launch rpm or pull some timing when you know the track is not there.

[Craig Hendrickson]

Originally Posted by GTO2nv

The car is a 71 GTO. (snip) The south side machine bars take place of the lower control arm and they are a lift bar.

"Lift bars" replacing the lower control arms do not do what you think they should do unless the upper control arms are removed and a panhard or other side force control setup is used. With the stock upper control arms in place, the rear suspension is essentially "locked up", moving only within the compliance of the pivot bushings.

[Craig Hendrickson]

To add to my previous post, here's a "Technical Topic" article out of H-O Racing's High Output Newsletter that I wrote back in the 1970s. It concerns A-Body rear suspension and the OP might find it interesting:

http://www.wallaceracing.com/coilspring.htm

What you apparently have is MAYBE like the "JR" bars cited in this article, except for my comments above.

I agree with a previous poster, with 11in slicks, you should be able to run low 10s if the suspension is "right."

[screamingchief]

Craig,the SSM "lift" bars for the A-body,so they are pretty much the same idea as the Ansen bars in that article.

They have/use a bracket that moves the rear/lower CA mounting point down to relocate the IC.

They also have solid/delrin insert bushings in them.

In my experience,the SSM set-up does'nt bind up the suspension.

But they will "hit" the tires harder due to the IC change and that of course causes the rear suspension to seperate as SOP as opposed to squatting like the OE IC location does.

HTH

Bret P.

[screamingchief]

IMO one of the most important things to watch when you use any suspension aids that try to force the rear suspension to seperate as opposed to squat is to watch the shock travel,if at any time the shocks reach full extension that's gonna kill the weight transfer dead in it's tracks,as that is essentially the same as the suspension binding.

I always closely monitor the shock travel in my drag cars.

Been a whole lotta threads covering this topic in the past,so a search of the archives would be a very good place to start.

I also agree a true ARB (anti-roll bar) is a better way to deal with the rotational "twist" issues as opposed to using the springs,shocks,and air bags for that deal.

And dont confuse the ARB with the OE anti-sway bar either,they're not necessarily the same thing.

I'd also highly recommend getting some of the spherical bushings for the upper/rear bushing as well.

If it is'nt over-extending the shocks and there is no bind in the rear suspension,then it may just be hitting the slick too hard and ya' may need to adjust the IC further.

Hitting the tire harder is not always the answer to this problem,sure enough sometimes it is,but other times it wont be the best answer.

No matter what,you gotta know that you can get the stock suspension to hook,so no you wont have to back-half to car to get it to hook,there are lots of A bodies out there with 60' times in the 1.20's with the OE 4 link set-up (w/mods),so understand that it can be done.

FWIW

Bret P.

[Craig Hendrickson]

ScreamingChief (Bret P): Thanks for the clarification. I also agree that there are many threads on this that the search results should pop up. GTOnv has some homework to do.

[Dragncar]

GTO2nv,you do not need to back half anything. Before you go that far you can just install a real 3 link.
I have done several on A bodies and you can get enough traction to run 9 flat with them and stock wheel wells.
A 36" is the best but they will come up into the car. Alston make a very nice 32" adjustable ladder bar. Once you install them you can pre load whatever wheel you want to. The car will lift dead straight on the nose, just grab and go.
I can run 1.4s 60 foots all day long with Hoosier 29x 12" slicks in stock wheel wells in a 69 GTO.
In back half'ing the car you cut it up and change everything. Serious commitment. With a 3 link all you have is 2 weld spots right where the frames narrows down. You can run the car like that for a few years and take the whole thing out like it never happened.
Its pretty cool for a semi serious racer. You can turn the adjust nuts a few flats and the car tilts one way or another.
Here is how good it works. I have 30 year old air shocks on the back and 90/10s in the front and I can not spin the tires. And I can adjust the rear height with a bicycle tire pump.
Its not like I have not thought about putting some nice coil overs on it.
But if I can not spin the tire with air shocks why spend the money on the coil overs?

BTW, I have seen several fast stock rear suspension A bodies crack the frame where the stock 4 link mounts.
Not a issue with a true 3 link.

[screamingchief]

Originally Posted by Dragncar

BTW, I have seen several fast stock rear suspension A bodies crack the frame where the stock 4 link mounts.

That's easily addressed,if the car is serious enough,and those owners did'nt brace/beef up the CA mounting points,then they likely did'nt know what they were doing in the first place,that or they were just too lazy/complacent to do the job right the first time.

Anything can break,even ladder bars (especially the rod ends).

If a fella wants a 100% guarantee against breakage,then this is probably the wrong hobby to be in.

Every chassis option has it's pros & cons...

JMO/FWIW

Bret P.

[GTO2nv]

The tires spin as soon as I let go of the trans brake,why does the car work sometimes and not all of the time?

[GTO2nv]

Should I throw away the airbag and put an antiroll bar in?

[HO 67 BIRD]

Has the pinion angle been checked?