| Post Info | TOPIC: Upper control arms - more caster? |
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What to do about upper control arms? [7 vote(s)]
| 1 - Leave as is, be careful cornering |
| 14.3% | | 2 - Buy the tubular control arms |
| 71.4% | | 3 - Fabricate your own control arms |
| 14.3% |
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davelacourse
Guru
Posts: 553
Date: October 23rd
| Upper control arms - more caster? |
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| Well I drove to the alignment shop, and he put the 56 with all new/rebuilt front suspension on the fancy computerized/laser-guided machine, and ... cannot get anywhere close to the factory specified 1 degree postive caster, and cannot get any positive camber either (toe-in of course is not a problem). Reason: very little adjustment built into these early cars, and I have dropped the front end 2 inches and raised the rear end about 4 inches, introducing over 3 degrees of negative caster into the front end.
Steering is OK driving down the road, turns really easily, BUT the return-to-center feature we are all accustomed to is gone - I have to crank it back to straight. So I have 3 choices:
1. Live with it. Drives OK except for the missing return-to-center feature which is kind of weird. But it does drive OK, no wandering, no pull, no twitching.
2. Buy a pair of tubular upper control arms that have 6 degrees more positive caster and 2 degrees more positive camber built into them. (They do this by relocating the upper ball joint towards the rear of the car and out a little bit too.) Easy bolt-in, cost about $350. Ouch, not really in the budget but you know how it goes. I would be wasting the parts (bushings and ball joints) and labor (to press the bushings out and in) I have in the original upper control arms, could put them on the shelf, maybe use them for some later project ...
The alignment guy can easily add shims to bring the caster and camber into line with specs with those control arms.
I am not a big fan of tubular control arms, they do not fit the type of car I am building, but I could live with them.
3. Fabtricate my own upper control arms. I have a spare pair of uppers that I picked up a while back. The bushings and balljoints in them are junk. And they need sandblasting or other cleanup for surface rust. But these are not a problem at all, for what I have in mind.
What I could do is cut both arms sort of in half, but in such a way that when you welded the pieces back together, the the upper ball joint would be moved towards the rear of the car and out a little bit too - giving you positive caster and camber. I have done the trigonometry (and here you thought nobody would ever use trig, eh?) and 1 inch to the back and 1/4 inch outward would be just right.
Here is how I would cut the pieces:
- This shows the two donor control arms, one laid on top of the other, one with the bushed shaft correct for bolting to the car, the other with the ball joint in the corrected location - you can see where the width of the 2 arms is the same so they could be welded together with minimal gaps:
- The spare control arms would be cut as shown here:
- And this is the part that would be used:
- The rebuilt control arms that are in the car now would be the donor for "Part b" because the bushings are brand new. I would also take the brand new ball joint off them and put the ball joints on "Part a" from the spare control arms. Here's the cut:
 - And here's the part that would be used: 
- End result:
I would have to farm out the fabrication, because I am not a good welder. I would do the "where to cut" on each of the donor control arms, because I *AM* a good mathematician and can make accurate measurements (I would probably fabricate a jig out of wood to ensure the balljoint would be moved the correct amout).
I would not grind the welds to keep the strength, so they would not be pretty, and with the angle being very obvious, they might look weird. But they would allow alignment to be done according to factory specifications.
What do you think?
Dave
P.S. if anybody wants to see the trigonometry calculations, just let me know. -- Edited by davelacourse on Friday 23rd of October 2009 12:29:10 PM-- Edited by davelacourse on Friday 23rd of October 2009 12:33:33 PM |
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eeluddy
Poncho Master!
Posts: 1568
Date: October 23rd
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Seeing that you have spent this time figuring out the fabrication, i say go with #3
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cdnpont
Poncho Master!
Posts: 1075
Date: October 23rd
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Nice drawings Dave!
Was the alignment (at least the caster) on a 56 not done entirely with shims anyway?
Shim in as much positive as you can get...find another set of arms on top of your spares, and start on your geometry project. Drive the car while you take your time working on the new arms.
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davelacourse
Guru
Posts: 553
Date: October 23rd
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Yes shims alone for caster and camber adjustment, they have been tweaked as much as possible, still a lot of negative caster and no camber. (Toe is set by adjusting tie rods.)
The alignment guy said "Just lower the rear" and I said "That is not an option" since I like the stance and also it's the only way those big tires will fit in there without cutting the wheel opening in the rear fenders (and I like the factory lines).
Thanks,
Dave
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427carl
Canadian Poncho Superstar!
Posts: 8705
Date: October 23rd
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| davelacourse wrote:
Well I drove to the alignment shop, and he put the 56 with all new/rebuilt front suspension on the fancy computerized/laser-guided machine, and ... cannot get anywhere close to the factory specified 1 degree postive caster, and cannot get any positive camber either (toe-in of course is not a problem). Reason: very little adjustment built into these early cars, and I have dropped the front end 2 inches and raised the rear end about 4 inches, introducing over 3 degrees of negative caster into the front end.
Steering is OK driving down the road, turns really easily, BUT the return-to-center feature we are all accustomed to is gone - I have to crank it back to straight. So I have 3 choices:
1. Live with it. Drives OK except for the missing return-to-center feature which is kind of weird. But it does drive OK, no wandering, no pull, no twitching.
2. Buy a pair of tubular upper control arms Easy bolt-in, cost about $350. Ouch
The alignment guy can easily add shims to bring the caster and camber into line with specs with those control arms.
I am not a big fan of tubular control , but I could live with them.
Buy the tubular ones LATER you can't make them for less than 350.00 Its a Hot Rod not a show car... tubular are cool and professionaly built 
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69 belair
Poncho Master!
Posts: 1899
Date: October 23rd
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davelacourse
Guru
Posts: 553
Date: October 24th
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| 69 belair wrote:
uummm, upper arms aren't on their wrong side are they? 
Whoa! That would have been really freaky, eh? Would have resulted in about 7 degrees negative caster, can't imagine what handling would be like then! Yep, they are on the correct side - I even went out to the garage just now to double-check 
Although that would have been a REALLY quick, cheap fix, eh?  Dave |
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tc
Veteran Member
Posts: 25
Date: October 24th
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Had a similar problem with a 61 Pontiac Tempest wagon I built a couple years back. Altered the upper control arms, relocated ball joint [Used Chrysler screw-in style] was a massive pain in the ass. In the end I went over to McColls racing products [London] and got off the shelf uppers [Cascar Tubular] and was done with it. It turns your problem into a no-brainer!!
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sixtywagon
Poncho Master!
Posts: 1300
Date: October 24th
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HMMM, Unless it really bothers you to have to "return" the steering to centre , everytime you make a corner, I'd leave it as is...Maybe purchase the tubular ones later on, if you feel nessesary
My 2 cents
Ken
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davelacourse
Guru
Posts: 553
Date: October 26th
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| Thanks for all the input, guys - I decided that I wanted the alignment done right, so even though I could live with it, I will change the upper control arms. And I decided to go with powder coated tubular upper arms from Eckler's - their Halloween sale was 15% off so I got them for $305 US, they have 5 degrees positive caster (mine is now 4 degrees on one side and 4 degrees on the other side, both negative caster - so adding 5 will allow both to be shimmed to the specified 1 degree positive), 2 degrees postive camber (mine is now a tenth or two negative, so this will allow shimming to the specified 1/2 degree positive).  Thanks again, I did take into account everything everybody said. Dave |
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427carl
Canadian Poncho Superstar!
Posts: 8705
Date: October 26th
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| EXCELLENT! although I gave you, permission to buy them later like next year
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davelacourse
Guru
Posts: 553
Date: October 26th
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| It's my early Happy New Year present to myself
Dave |
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427carl
Canadian Poncho Superstar!
Posts: 8705
Date: October 26th
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