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Username Post: Need advice on control arms        (Topic#359622)
JayChicago 
"10th Year" Silver Supporting Member
Posts: 372
JayChicago
Loc: Chicago
Reg: 01-03-13
01-28-20 11:24 AM - Post#2785360    

Slow winter, been noodling over two issues on my '58 that I would like to get resolved this summer. I am clueless on steering / suspension, so I need advice.

No. 1:
Car is way out of spec on camber and can't be adjusted more. Has frame fatigue from carrying the weight of an engine in the cradle for 60+ years. A local old-school frame straightening shop said they can do an expensive "spread for camber" procedure, something they were doing commonly 30 years ago on old daily drivers. But I'm skeptical of doing that...will it last? And what other problems may develop when they are doing this, forcing the frame. Scares me. Seems to me a better way to go is with the offset upper control arm shafts available today. What do you think? Camber now is -1.9 and -1.3, when it should be 0 to +1. So it needs 2 to 3 degrees more camber.

No. 2:
Lack of caster. I have a CPP 500 steering box in the car now. (also has new springs and larger sway bar) Steering is great, but the car wanders. No wonder, because caster now is -1. I have read here that with a modern box it needs aftermarket upper control arms that will give +4 degrees caster. Your thoughts on that? And can this be done with the offset shafts?

Any advice is appreciated, including what other problems I may be getting into that I don't know enough to think about now. BTW, I won't be attempting to do this kind of work myself, will pay a pro.



 


japete92 
"6th Year" Silver Supporting Member
Posts: 1301
japete92
Loc: No. Virginia
Reg: 01-18-13
01-28-20 01:28 PM - Post#2785368    
    In response to JayChicago

  • JayChicago Said:
Slow winter, been noodling over two issues on my '58 that I would like to get resolved this summer. I am clueless on steering / suspension, so I need advice.

No. 1:
Car is way out of spec on camber and can't be adjusted more. Has frame fatigue from carrying the weight of an engine in the cradle for 60+ years. A local old-school frame straightening shop said they can do an expensive "spread for camber" procedure, something they were doing commonly 30 years ago on old daily drivers. But I'm skeptical of doing that...will it last? And what other problems may develop when they are doing this, forcing the frame. Scares me. Seems to me a better way to go is with the offset upper control arm shafts available today. What do you think? Camber now is -1.9 and -1.3, when it should be 0 to +1. So it needs 2 to 3 degrees more camber.

No. 2:
Lack of caster. I have a CPP 500 steering box in the car now. (also has new springs and larger sway bar) Steering is great, but the car wanders. No wonder, because caster now is -1. I have read here that with a modern box it needs aftermarket upper control arms that will give +4 degrees caster. Your thoughts on that? And can this be done with the offset shafts?

Any advice is appreciated, including what other problems I may be getting into that I don't know enough to think about now. BTW, I won't be attempting to do this kind of work myself, will pay a pro.




Comment on No.1:

I do not have experience with bending/spreading car frames. But, I have a BS in civil engineering, an MS in naval architecture. Before retiring, I worked as a naval architect for 40+ years. I know steel structures and how they behave.

Steel does not weaken with 'age/time' without reason. Two reasons are corrosion and fatigue loading.

Corrosion weakens a structural member by reducing the 'amount' of 'steel' supporting the load. A steel structural 'member' that has lost some of it load bearing ability due to corrosion, does not gain it back by bending it back into it's original shape. Replacing the 'lost' material is required to restore 'strength'.

Fatigue is a repeated cyclic loading that causes failure at loads much smaller than under more simple load bearing scenarios. Again, the 'strength' does not return w/o 'repair'.

Your frame has likely experienced reduced strength from corrosion loss. Fatigue 'weakening' is also possible, it would have come from the flexing of the frame during MANY miles of driving.

Comment on No.2:

Increasing the caster to something like +4 degrees should help your 'wander'. It certainly did on my '63 when I installed a Borgeson box (a 'cousin' to the CPP as I understand them). You may be able to find 'after market' stamped steel upper control arms for your '58. I seem to remember seeing some when I was looking for my '63. However, on my '63 the only option I found were tubular.

But....

I would NOT spend money on the control arms w/o properly restoring the strength/configuration of the frame.

Pete








 
4spd409 
"14th Year" Silver Supporting Member
Posts: 616
4spd409
Loc: Sherwood ND
Reg: 10-10-02
01-28-20 07:14 PM - Post#2785385    
    In response to JayChicago

Not much I can add to Japete92's comments. If the frame has corrosion issues (rust) the only real way is to replace it. If is fatigued it probably could be straightened but would need to be reinforced someway. I used offset upper control arm shafts to get about 2 degrees positive caster which made the car drive great. They are available from either Summit or Speedway.

61 Impala Bubbletop


 
JayChicago 
"10th Year" Silver Supporting Member
Posts: 372
JayChicago
Loc: Chicago
Reg: 01-03-13
01-29-20 01:30 AM - Post#2785389    
    In response to 4spd409

Thanks to you both. Yes, I don't think I should let them do anything with the frame. There is no corrosion. Perhaps the frame rail has twisted inboard where the control arm attaches at the top of the rail, but if so it is minimal, can't be seen by eye.

With a little research I found the aftermarket has already recognized a need and designed tubular upper control arms that will probably address both my issues. Here's Global West's product demo:
https://www.youtube.com/watch?v=ZFCohmc-BmA&a mp;fe...



 
japete92 
"6th Year" Silver Supporting Member
Posts: 1301
japete92
Loc: No. Virginia
Reg: 01-18-13
01-29-20 09:12 AM - Post#2785409    
    In response to JayChicago

  • JayChicago Said:
Thanks to you both. Yes, I don't think I should let them do anything with the frame. There is no corrosion. Perhaps the frame rail has twisted inboard where the control arm attaches at the top of the rail, but if so it is minimal, can't be seen by eye.

With a little research I found the aftermarket has already recognized a need and designed tubular upper control arms that will probably address both my issues. Here's Global West's product demo:
https://www.youtube.com/watch?v=ZFCohmc-BmA&a mp;fe...



I actually bought and installed those uppers on my '63 to get the increase in caster required with the change in power steering (from OEM to Borgeson). I like them. I also bought their sway bar and like that too.

I had to stop watching the video because of all the BS being spewed. "Impala's have alignment issues...". No they don't. A stock x frame Chevy's alignment is correct for the components it was design for. "... only have +1 degree of caster....". True; but it 's not a problem with OEM steering. I'll stop because I'm too lazy to type any more about it. They spread the same type of BS in their 'bump steer' video. Their marketing POs me

As I said before, I would NOT spend any money on the control arms until I got the frame fixed. Doesn't sound like that's what you want to hear, but that's the reality of the situation (as you have explained it and as I see it). I don't see an 'easy' fix.

IF the frame was bent in a collision, MAYBE it can be straightened 'in place'. I'm not experienced in that, and don't know what's 'doable'. The biggest risk is the 'straightening' may cause tiny cracks in the steel. Tiny cracks produce stress concentrations that propagate into larger cracks which lead to failure of 'structure'.

Just trying to be helpful.

Pete






 
ragtp66 
Contributor
Posts: 859

Reg: 12-09-07
02-01-20 05:30 PM - Post#2785637    
    In response to JayChicago

Just to add some food for thought keep in mind the 58 spindles and brakes were slightly different than the 59-64 narrower brakes and different part numbers for the spindles so most parts are generally designed around the 59-64 geometry and specs. I cannot see any reason the offset upper shafts would not work to pull the top of the tire in more towards the spark plugs so I would move in that direction first. If you are not running the stock 58 steering box and column this should not be a problem. I can see where things could get close to coming in contact with a stock steering box. I am not one to believe in the frame sag BS I think as was stated if it was rotted or previously wrecked then straightened I could understand how it could be out of spec over time. If any bushings are dry rotted or worn I would suspect they could cause problems as well. These cars definitely had issues in the steering box mounting area even when new. The fact that there were three different suppliers each making frames (A.O. Smith, Budd, and Chevrolet) but also three completely different ways lends to the margin for error. I also know firsthand that if the front coils are not installed correctly and clocked properly you can have alignment issues, they need to be seated in the upper frame pocket properly and located in the lower control arm properly as well. I hate working with front coils as they always make me pucker up a bit especially on these cars the way the front coils take on an arched Banana shape when they are installed.

Toys:
1958 Impala 2dr Hardtop Under Construction
1966 Chevelle Malibu Convert M20/350 Aztec Bronze
1987 Sea Ray Pachanga 22
2002 Cadillac Escalade EXT Parts chaser
2007 Trailblazer SS -gone and missed


 


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