62 Chevrolet, STILL No Traction

[casper]

Aubrey ... heres my .02 from what I have learned from my car ..67 Camaro F/S .. you have seen it in the Hat before . You stated :
"There are 11 full "turns" of the adjuster bolts, from nothing to max.
This is set 4 1/2 "in". .... if you have 11 turns available , and are 4 1/2 in from full out (which is max pressure) then that is leaving you at 6.5 turns "out" from base ... which is probably too much . That static pressure, along with counter weight pressure is more than likely contributing to blowing the tires off ... In my car , with 6 turns (out)in the clutch I can 60' in the 1.55-1.57 range and spin the tires on the gear change. With 2.5-3 turns "out" I can 60' in the 1.48-1.51 range and the gear changes are a little smoother ... so-to-speak.
There is a fine line between "going fast" and "going rounds" as any stick racer will tell ... Rob Youngblood has too much of my money for "freshening jobs" .. but thats a different story.
Tire pressure .... in my car (3215 lbs.) leaving at 6200-6800 I can get away with as little as 10.5 lbs .. but 12.0 seems to be the best. Some of those B/S 396 cars can run low pressure and get away with it .. so you should be able to get down there without running on the rims.
my best advice to you would be to buy a Autometer Ultimate II tach that will give you data about driveshaft speed and engine RPM. At least that way you can visualize when, and for how long the tires are spinning, or not spinning.
If you are going to be at Medicine Hat , stop by the trailer and I can show you the data I've collected with my tach... show you the difference of a 1.50 60' verses a 1.59 60'.

Mike

[Mike Pearson]

You will have to make some adjustments to the attachment at the rear end housing and the frame to get the proper geometry. there is no way the car will work in its present set up.You might be able to put a band aid on it by slipping the clutch. but that will create excess heat and the clutch will fail prematurely and the car will be inconsistent. Lower the ride height and extend the lower brackets on the rear end housing as much as you think you can get away with. Fabricate them to look as stock as possible. This is definatley your problem.

Mike

[Dwight Southerland]

Originally Posted by NHRAstocker409

I did a full series of measurements. Here's what I came up with:
( it's a factory "4 link" )
Distances from ground:

lower mount at housing... 8.75"
Upper mount at housing... 19.75"
Lower mount at frame... 12.125"
Upper mount at frame... 19"

I agree with Mike wholeheartedly. When I first read your post, the difference in measurements of the upper and lower bars jumped out at me. The upper bar is almost flat and the lower bar is pointed "uphill", so to speak. You will never make that work. The lower bar needs to be at least parallel to the ground, preferably pointed "downhill" from the axle like Mike said. The upper bar should be pointing downhill a lot.

You may need some work with the clutch settings, too. You have been given some good suggestions in the other posts, so I won't add anything else.

Once you get past these two areas, you will find some improved ET performance with lower trans gears. Be thinking in the range of 3.15 - 2.00 - 1.40 for the weight you are carrying. ET will be made in the first 330 feet; from that point on you are mainly carrying the weight.

Good luck and don't get discouraged! You have such a neat car and I applaud you for the resolve to crank it up!

[Aubrey N Bruneau]

This is TREMENDOUS, guys !!
All the replies, covered EVERYTHING
I''ve got a new fuel pump / system coming in on Tuesday ( actaully dropped to zero fuel pressure at top of 1st and 2nd gear ! ).
During this time, I'll "adjust" the rear springs in order to get the rear ride height where it should be.

oh... Mike.... that was YOUR car ?????!!!!!!!
Got some photos of THAT one !
clutch pedal forever !

[Bud Lefevre]

What is your pinion angle set at and what kind of bushings are you useing ?

Here's another web site that might help some

http://www.baselinesuspensions.com/index.htm

[Aubrey N Bruneau]

That was informative, Bud... informed me that ALL the factory mounting bracketes on the rear housing and the frame, are quite simply, fundamentally, in the wrong location !
Both upper and lower re BEHIND the axle centre... apparently counter-productive.

May have more of a problem than I thought.

[NovaMan]

Mike and Dwight, are you saying she needs to lower her IC and move it back? According to Baseline Suspensions, a higher and farther forward IC tends to plant the rear tires harder and lift the nose. Why would that be bad?

[rallye bob]

May be some useful info here.... http://home.earthlink.net/~whshope/index.html

(((Sorry Leif (Andersson). Just saw your post. My bad)))

[Dave Goob Cook]

I bracket race a factory 4 link car, (Malibu) all bushings in the rear bars are solid except the upper housing bushings, pinion angle is critical, I MUST have at least 4 degrees negative, runs best at 4 1/2 degrees. Now how you measure pinion angle is a subject for much debate, but I measure relative to the ground and frame (at ride height) plane.
I feel like what makes the rear suspension work is the "allowed" pinion rotation of the upper bushings at the housing.
I get probably 4"+ of separation at the rear axle, or plant on the tires, however you want to look at it.
Atlas non-gas shocks on the rear, QA1's on the front.
My setup is the old Southside Machine deal, the lower bars point "up" at an insane angle due to being located low on the axle housing. Upper bars are near level.
Your long wheelbase is a bit of a conundrum, in my opinion, although your weight bias is much more favorable than mine. (1660 frt / 1440 rr empty)

The M/T "stick" 29.5x9 tires are the absolute WORST tires I've ever run on my car, I usually run only Goodyear D-4A Radials (at 16-16 1/2 psi) for warm tracks. (6303's)
I'd think that a stiff sidewall or radial slick would be the ticket for you.

1.37 to 1.39 short times at any track with decent air, 1.40-1.41 when the HP is low.
Of course, it's an automatic, 2.10 low ratio TH-400 with 5200 stall off the t-brake and 3600 two-step, but the "hit" is fairly solid. Had no trouble with the 2.48 low ratio though, just made the car feel better with the 2.10 ratio. 4.11 rear gears.

I will agree with others that some quality video of your car is mandatory to study what is really happening. Nothing like a frame by frame playback to see things you never thought of.

Don't think you'll ever see the potential of your car until you can stand it on the rear tires at launch.

[Mike Pearson]

Nova man,

you can raise the IC in the car as long as you dont make the bottom bar run uphill in the front. You need about 2 degrees down angle and 2 degrees pinion angle. pinion angle is the difference between the angle of the driveshaft to angle of the pinion shaft. If you have rubber bushings in your link bars you will need more pinion angle. You should install solid bushings.

Mike