Author Topic: Where/How do UCAs flex?  (Read 1255 times)

Offline ChallengerHK

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Where/How do UCAs flex?
« on: April 08, 2008 - 07:25:44 PM »
I just finished upgrading the front suspension, with all the parts I bought before I was laid off. The one thing that didn't get done was the UCAs, I was going to replace them with tubulars, but needless to say I don't have the money to spend. I did have the LCAs boxed, and this started me thinking, "CAn the same thing be done with the UCAs?" As I thought about it, it depends on where and how the stamped steel arms flex. Any info?


"She'll make point five past light speed. She may not look like much, but she's got it where it counts, and I've made a lot of special modifications myself."

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Offline Moparal

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Re: Where/How do UCAs flex?
« Reply #1 on: April 08, 2008 - 10:41:37 PM »
I never really have seen an uca have issues bending in everyday driving.  The bushings can be an issue as the ball joint threads stripping an issue, but flexing I havent experienced before. I thought you were an ole geezer like me  ;D Do you plan on road racing your car? The regular uca's last 100k miles plus and have no issues unless abused. 

I know, I know...I'm no help

Offline ChallengerHK

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Re: Where/How do UCAs flex?
« Reply #2 on: April 08, 2008 - 11:31:49 PM »
No problem at all, Al, and thanks for the info. I'm 46, I just look like an old geezer  :bigsmile: 

As I've been saying for years, nothing makes me feel 16 again like driving the car I drove when I was 16. It's probably true that I won't drive it again like I did when I was 16 (I've learned a bit since then so hopefully I drive it better) but if I ever get to the point where I'm afraid to drive it hard I hope they take me out to the back 40 and shoot me  :ylsuper:


"She'll make point five past light speed. She may not look like much, but she's got it where it counts, and I've made a lot of special modifications myself."

- Han Solo, Star Wars

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Offline Chryco Psycho

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Re: Where/How do UCAs flex?
« Reply #3 on: April 09, 2008 - 04:03:28 AM »
I am not aware of any way to stiffen the UCA they are under far less stress than the lower front to rear deflection & in & out would be the main issues vertical is no big deal ........ not sure how I would re-inforce it that would help

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Offline Aussie Challenger

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Re: Where/How do UCAs flex?
« Reply #4 on: April 09, 2008 - 05:39:43 AM »
  The main reason tubular UCA's are used is that you can get better front end angles and it is easier to make than trying to stamp a new arm.  just my   :2cents:
Dave

Offline HP2

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Re: Where/How do UCAs flex?
« Reply #5 on: April 09, 2008 - 08:50:30 AM »

They flex along their entire length. It is marginal flex compared to the bottom, but it does when heavily loaded. The biggest issue in heavy duty, super speedway applications from way back when was the area around the ball joint. I've seen pictures of Petty cars that have several heavy beads of weld applied around the ball joint area to reinforce it.

It would be possible to brace an upper arm as well. The rolled lip along the edge is the perfect channel for capping, which would create, in an essence, a tubular reinforcement.

Offline ChallengerHK

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Re: Where/How do UCAs flex?
« Reply #6 on: April 09, 2008 - 09:16:18 AM »
It sounds like the consensus is that it can be done, fairly easily, but with little payoff unless I'll be over regular highway speeds for extended periods. Correct?


"She'll make point five past light speed. She may not look like much, but she's got it where it counts, and I've made a lot of special modifications myself."

- Han Solo, Star Wars

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Offline HP2

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Re: Where/How do UCAs flex?
« Reply #7 on: April 09, 2008 - 11:03:32 AM »
Pretty much.

If you ever do any track days or autocross, it may be of benefit to just firm up steering response and make it more precise.

Like Aussie Challenger said, the biggest benefit of tubular arms is the increased caster that can be built into them. Lighter weight and higher strength are just bonuses. You also can easily change the camber gain produced during suspension cycling by altering the length of the upper arm. Certainly this is easier to do with a fabricated arm than a stock arm. For a street car, that isn't a huge concern, but if your ever doing track stuff, it can have a big impact on keeping the tire flat in the corners.

Offline ChallengerHK

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Re: Where/How do UCAs flex?
« Reply #8 on: April 09, 2008 - 11:20:45 AM »
Thanks for the info guys. For right now I'll ignore the issue, and once I'm employed again I'll revisit the tubular idea and look at the effects of increased caster with a Firm Feel steering box.


"She'll make point five past light speed. She may not look like much, but she's got it where it counts, and I've made a lot of special modifications myself."

- Han Solo, Star Wars

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