Recommendations for alignment setting?
#2712802
11/04/19 08:06 PM
11/04/19 08:06 PM
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Joined: Apr 2006
Posts: 4,220 West Plains, MO
DrCharles
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OP
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West Plains, MO
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While my '72 Dart is on jack stands with the K-frame dropped (waiting for my 1.03" t-bars, also have a couple of other things to debug), I am thinking about alignment specs. I'm familiar with Richard Ehrenberg's "Skosh Chart" but would like to hear from others who drive on the street. Tubular UCAs, manual 16:1 box, 195/70-14 front tires. 451 low-deck, currently iron heads but going to aluminum next year, 4-speed. I am fairly good-sized so steering effort isn't too big a concern, but I will probably be more on the street than at a track. The more I read about increased caster and negative camber, the more confused I get. I believe the tubular UCAs have +4 caster built-in, so a shop can easily set it to that much or more. I'm thinking about +4 caster, -0.25 camber and 1/16" toe. Thoughts?
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Re: Recommendations for alignment setting?
[Re: DrCharles]
#2712856
11/04/19 10:31 PM
11/04/19 10:31 PM
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Joined: Nov 2003
Posts: 36,041 Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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I'm thinking about +4 caster, -0.25 camber and 1/16" toe. Thoughts? I'm OK with those #'s
live every 24 hour block of time like it's your last day on earth
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Re: Recommendations for alignment setting?
[Re: DrCharles]
#2712956
11/05/19 11:29 AM
11/05/19 11:29 AM
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Joined: Jan 2003
Posts: 5,394 Pikes Peak Country
TC@HP2
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Pikes Peak Country
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195mm tires with 1.03 t-bars is an odd combo. You will likely have significant understeer if pushed in the corners, just so you are aware. However, the skinny tires will make steering effort easier while the manual box will make it more difficult. I assume with metric measurements, they are radials and not bias ply drag tires.
In a drag car you would want everything to be as close to zero as possible while under acceleration so specs would be set with 1-1.5" of front end rise and angles would be set to maximize the zero point. If you are more street oriented, then I wouldn't worry about it. However, in street cars you want more negative camber to allow better tire to street contact during cornering and body roll. You also want higher positive caster to improve return to center, step up steering resistance, and provide high speed stability.
Since you have manual steering, skinny tires, and heavy t-bars, I'd agree with your specs to see how it feels. The effort required for a +4* caster will likely be offset by the 195 tires, so that may be kind of a wash. If the effort is too high for your taste, then back down the caster some.
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Re: Recommendations for alignment setting?
[Re: TC@HP2]
#2712974
11/05/19 12:06 PM
11/05/19 12:06 PM
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Joined: Apr 2006
Posts: 4,220 West Plains, MO
DrCharles
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Posts: 4,220
West Plains, MO
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Thanks for the info. Yes, radials all round. The 1.03 seemed to be a good compromise between "mushy" front end and too-stiff for the street. Darts with big-blocks in the nose are not generally known for superb handling or oversteer It was even worse when I had an A-body with an iron 440 and a 6-71 blower I'm primarily interested in going fast in a straight line anyway (295/50-15's out back). I know that increased caster provides high speed stability with increased steering effort. But just how much of an increase? If going from, say, +4 to +6 caster, does the effort rise by 5%? 10%? 25%? I've also read that too much caster can be a bad thing since the camber in turns becomes severe and limits the contact patch (tire rides on one edge). Presumably the tubular arms are made with +4 for a reason...
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Re: Recommendations for alignment setting?
[Re: fal3]
#2713097
11/05/19 06:18 PM
11/05/19 06:18 PM
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Joined: Jan 2003
Posts: 20,894 A collage of whims
topside
Too Many Posts
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Too Many Posts
Joined: Jan 2003
Posts: 20,894
A collage of whims
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Last BB A-body - with QA1 arms - I ran 4.5 deg caster, and that was nice. manual steering car, no problem parking and I'm just a skinny guy. It ran 1 deg neg camber, 1/16 toe. My SB drag car (sig pic) runs about 7 deg caster, 0 camber at running height, 1/16 toe, goes straight as a string. But with the wheel turned, it self-centers with a vengeance. Definitely a difference in effort, but the 2 cars have different jobs.
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Re: Recommendations for alignment setting?
[Re: DrCharles]
#2713121
11/05/19 07:33 PM
11/05/19 07:33 PM
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Joined: Feb 2010
Posts: 1,645 Phila. Pa.
Mattax
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Posts: 1,645
Phila. Pa.
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Thanks for the info. Yes, radials all round. The 1.03 seemed to be a good compromise between "mushy" front end and too-stiff for the street. Darts with big-blocks in the nose are not generally known for superb handling or oversteer It was even worse when I had an A-body with an iron 440 and a 6-71 blower I'm primarily interested in going fast in a straight line anyway (295/50-15's out back). I know that increased caster provides high speed stability with increased steering effort. But just how much of an increase? If going from, say, +4 to +6 caster, does the effort rise by 5%? 10%? 25%? I've also read that too much caster can be a bad thing since the camber in turns becomes severe and limits the contact patch (tire rides on one edge). Presumably the tubular arms are made with +4 for a reason... With 4* caster you may have to be disciplined with your hands when turning the wheel. The steering wheel can easily snap back to the straight position if you let go at the wrong moment/situation. I don't know that you find any noticble increase in stability on the highway. The higher positive caster is useful in adding negative camber during a turn where the chassis is rolling. For this the tires need to be sticking. Which leads to your last questions - the caster and camber need to match the tires, road condition as well as the suspension. Since you're not road racing, autocrossing or such, just keep everything moderate.
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