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New Front Control Arm


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Attached are pictures of my new front control arms (as yet unmounted). The main body is a 1.125" OD rod that was drilled and tapped on both ends to accept a rod end on the outboard end and a double adjuster on the other end. The angled cross piece is a .875" OD rod tapped to accept an inner steering tie rod I used from a Z31, which acts as the outer end of the TC rod. I had a pair of machined clevises that I used for the attachment of the other end of the TC rod to the chassis. The TC rod is also RH/LH threaded to allow adjustments in length. I used a high misalignment rod end outboard for attaching to the steering arm because my steering arms are already drilled out to accept a 5/8" bolt. The outboard rod end is not used for any length adjustments, only the double adjuster. Just thought I'd post them and see what others thought.

 

Mike Mileski

Tucson, AZ

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Don't want pivots at both ends of the TC rod. Rear pivot only. Front attach point needs to be strong, and ideally the TC rod itself would point as closely as possible towards the ball joint pivot. That loads the TC rod straight on. If the rod is offset inwards (like drifters tend to want so they can get more steer angle) then the rod itself and the attach points need to be strong enough to take the side loading involved.

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Well, I'm glad I had most of this hardware already "laying around". The only money I had to spend was for the 1.125" metal rod material  I wasn't aware that the TTT rods changed from standard rod ends to solid. Back to the drawing board for me. Thanks for all your input.

 

Mike Mileski

Tucson, AZ

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Bad idea IMO. As you adjusted caster you'd put major stress on the threads. If you made them to the length where they fit into the TC buckets without loading the threads, maybe that's OK, but the idea looks to be to make everything adjustable. 

 

Another possibility would be to get a male clevis that screws into that existing threaded hole, but if there's not a whole bunch of money tied up in it I'd rather have a clevis welded to the arm and a solid heims joint or "rod end eye" as it's sometimes called on the TC rod.

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Yes, I have the steering arm drilled out to accept a 5/8" bolt. I have also figured out how to make a solid connection at the arm. I had some clevises with a 5/8" gap and a 5/8-18 male thread (see pictures). I was able to drill the cross piece out and tap it for a 5/8-18 thread, screw in the clevis and I'll have it welded directly to the arm to make a solid connection. I then found some solid rod ends that were 5/8" thick wiith a 5/8-18 male thread. Once I drill and rethread the arm side of the TC tube to a 5/8-18 RH thread , I'll be all set. Even the length dimension will remain the same.

 

Mike Mileski

Tucson, AZ

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Yea the problem with rodends/pivots everywhere is that the swaybar pushes and the arm tries to rotate instead of applying the force, until it hits the limit of rotation....

 

I have seen inner tierod based tension rods before, but I haven't seen any data or long term reviews to know if they can hold up to the constant tension stresses applied. In a steering application most of the force is compression...

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I would think they would hold up fine given that they would mostly be under compressive forces given their angle short of a wheel going off track and trying to pull the car back on I don't see any real stretching force applied. If say the tie rod was inboard located at the TC bucket and a solid clevis used I think it would still function well.

 

Using the solid clevis turns this setup basically into an A-Arm of sorts locking the tension arm to the main control arm during suspension travel. During braking the force will be transmitted directly to the bucket and has no risk of collapsing the arm as there would be with two joints as I understand it. I'm not sure the sway bar comes into play here.

 

The only concern I may chime in with would be material thickness and strength. I want to say the T3 arms employ some very large threading more in the 3/4 range if memory serves for the threaded bits.

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In a solid a-arm style setup, like the s13 or z31 where the tension rod solidly bolts to the arm with no flex between them, I would say even 5/8" rodends are fine for the inners, but because there is a ton of bending force applied at the outer, that should really be large like 3/4"...

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  • 1 month later...

Here's what I ultimately ended up doing:

Picture 1. Drilled a 3/4" hole at the correct angle through the main body of the arm. Inserted 3/4-16 Grade 8 bolt.

Picture 2. Welded both sides and cut/ground off excess material on backside

Picture 3. Finished new arm

 

Mike Mileski

Tucson, AZ

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