Tubular Lower Control Arm Thread

-
B

Badart

Senior Member
Joined
Feb 14, 2009
Messages
5,170
Reaction score
87
Location
Northern Utah
Well I have had the idea of building these rolling around in my head for a while now and due to the fact that this has been keeping me up at night thinking about it, I am finally going to do it.

My goal is to build tubular lower control arms that will be used with coilovers and eliminate the torsion bars. Here is the kicker, it will use the factory K member with little to no modification to the K member. It will also use the factory spindles, ball joints, strut rod and sway bar mounts. For those of you naysayers start, the LCA's will have three attachment points to the K member and will be very strong. I plan on using urethane bushings instead of heim joints, so daily street driving will not be an issue.

I have already collected some parts, dies and tools are on order to get this going. I will be building a couple of jigs over the next few days. The LCA's will be fully tig welded and stronger than other arms that are out there. I have a habit of building things overkill. My test mule is a fabo member that beats the crap out of his cars and if they pass his inspection then he will be installing them on his car first.

Those of you that want to start bashing have at it. :D

Here is what I am starting with. It's a very rusty, but straight K member from a 73 equipped with a sway bar.
 

Attachments

  • K member.jpg
    101.8 KB · Views: 4,512
  • LCA 1.jpg
    109.2 KB · Views: 4,127
  • LCA 2.jpg
    120.2 KB · Views: 3,956
  • LCA 3.jpg
    124.6 KB · Views: 4,153
can't wait to see what you (and us "helpers") come up with.........no joke
 
Don't you just hate it when stuff like this keeps you awake at night?? Good luck...
 
I'm still "figgurin'"...

Denny...AKA...Rube Goldberg
 
Great idea. Will these be built to allow some additional caster?
 
Badart said:
My initial plan it to do the pivots in a flange type urethane bushings with the factory caster.
Click to expand...

If you could move the lower ball joint forward 3/8 of an inch you'd gain about 3 degrees of positive caster which would improve the front end geometry a great deal. IMHO, that would be the only reason to get the tubular UCA's.

If your LCA's had the same effect, plus you get to ditch the torsion bars I think you'd have a winner on your hands.
 
I hope you can figure it out, might work out well for me with the way my cage is made.
 
Something I used when designing mine is Racing Aspirations, Suspension Geometry Calculator. Fantastic program.and easy to use.
 
Very cool! I wish you nothing but success.Im sure you will turn out nice pieces,after all the rad support and other stuff you make is nice indeed!
 
Can't wait!!! The excitment is killing me.
 
fzmax said:
If you could move the lower ball joint forward 3/8 of an inch you'd gain about 3 degrees of positive caster which would improve the front end geometry a great deal. IMHO, that would be the only reason to get the tubular UCA's.

If your LCA's had the same effect, plus you get to ditch the torsion bars I think you'd have a winner on your hands.
Click to expand...

With these you will have to go to tubular UCA's anyway, because of the coilover so I think any caster/camber adjustments could be made there. Thank you and love your car btw.
 
Coronet 500 said:
Something I used when designing mine is Racing Aspirations, Suspension Geometry Calculator. Fantastic program.and easy to use.
Click to expand...

Thanks and I will check it out. I plan to build a jig with all of the factory geometry first and just copy that first.
 
Any chance you'd consider making tubular LCA's for the stock torsion bar set up? You know, for those of us that want lighter, stronger LCA's but don't want (or see the need) to ditch the torsion bars?
 
Aside from it being overbuilt from the factory because it is designed to take the suspension loads, and triangulating a bracket to put the inner end of the control arm in double shear, there is no reason to screw with the K frame at all.
Being that all the work is going to be in strengthening the engine box and longitudinals for the upper shock mounts, building those mounts, making everything hell for stout (because you're now jacking all the corner weight into the top of the engine box instead of the middle of the chassis through the floor shear plane), and coming up with tubular upper arms to allow shock clearance, why not just weld boxing plates to the bottoms of late B body lower control arms (78 Cordoba, etc.)?
BINGO! Tubular lower control arms with a flat upper surface to mount shocks to and a shape that naturally provides more suspension travel. You just need to use longer upper arms to match their slightly longer length and machine an insert in place of the T bar to take a bolt through the newly added bracket mentioned above. Wacking off the control arm pin and drilling and tapping it to take a mounting bolt should be child's play after that.
No worries about suspension geometry, because it remains all stock!
 
Spent a little time this evening degreasing and media blasting parts. Tomorrow I will start on the jigs.
 

Attachments

  • K member clean.jpg
    101.9 KB · Views: 3,700
72bluNblu said:
Any chance you'd consider making tubular LCA's for the stock torsion bar set up? You know, for those of us that want lighter, stronger LCA's but don't want (or see the need) to ditch the torsion bars?
Click to expand...

Don't get me wrong I like the torsion bar suspension, but I feel like in certain situations there is a need for these without dropping a ton of money for an Alterkation. I think that the stock LCA's are well designed and work great when reinforced properly.
 
You must log in or register to reply here.
-

Back
Top