My Car So Far...

[Steve Hoelscher]

So ever since I first looked at the control arms I said this is wrong. What Im talking about is the huge unclosed gap here ( dont mind the damage, I think this arm was curbed at some point)

View attachment 10507

To me this area, and opposite side, create a scenario which is just begging for twist and distortion under load.

So my plan is to partially close (box) the middle points of the control arms where I imagine there being the most flex with a bit of steel plate. Did fiat intend for this to flex? Seems to me like a bean counters compromise more than anything

I agree. The open channel control arm is prone to flex. Certainly, this was due to being inexpensive and easy to manufacture and not because they wanted the flex. For a standard road car they are plenty strong.

I have welded a plate of similar thickness over the opening to box in the control arm and improve its stiffness. These also incorporated spherical bearings in place of the bushings.

 

[Steve Hoelscher]

Steve actually the front springs are 600.225.450...Facepalm.... its not my fault I swear

PO strikes again

So the frons are 25 lbs/in stiffer than the rears. For an autocross or track car you will want to use a front swaybar if you are to use these springs. You will need more front roll stiffness to balance the handling. Or just run a stiffer front spring.

 

[Ben Louis]

Straightening jig for the arms. Access constraints limit your options with a hammer and buck... it works just good enough

A little heat helps the metal relax a bit too
Eagle eyed viewers will notice a crack picture center. This was a result of whatever impact this arm took. Itll be ground out and welded up when I weld a strengthening plate to this side

 

[Ben Louis]

Steve did you box the whole section?
I do have a front sway bar, so thats some good news
So maybe stiffer front springs arent so bad?

 

[Ben Louis]

This is why I challenge... because of a good defense
Thanks for the info!

 

[Steve Hoelscher]

Steve did you box the whole section?
I do have a front sway bar, so thats some good news
So maybe stiffer front springs arent so bad?

Yes. Welded the ends to the adjacent sections too. Once it was boxed, and thus stronger, I used the hole saw on the additional section to reduce the added weight.

 

[Steve Hoelscher]

This is why I challenge... because of a good defense
Thanks for the info!

That's how I learned starting out. Pose an idea, let people critique it, then defend it. Your defense will either re-enforce your position or you will realize it was faulty. Or needed refinement. Regardless, it helps you develop critical thinking and applied ingenuity.

Do you have any idea how many people I have told they shouldn't use poly bushings in a particular application who told me I was stupid?

 

[Steve Hoelscher]

Straightening jig for the arms. Access constraints limit your options with a hammer and buck... it works just good enough

View attachment 10508

A little heat helps the metal relax a bit too
Eagle eyed viewers will notice a crack picture center. This was a result of whatever impact this arm took. Itll be ground out and welded up when I weld a strengthening plate to this side

Sweet. The plate I welded over the opening wasn't exactly a plate. Well, the first car I did was. The next one I used a sheet metal break to form a shallow "U" channel that fit inside the box. I then drilled a series of small holes long the edge of the control arm. After fitting the U section into the opening of the control arm I then welded through the holes and then along the seam. The result was ridiculesly strong.

 

[Ben Louis]

Its getting there

Hmmmmm...

Do you mean something similar to this? (Shallow U)
I would probably do a couple sections instead of the whole length but it is a good fit.

 

[Steve Hoelscher]

That appears to be a piece of angle. The piece I bent was only about 1/4" deep. Like this: I_______________I

You want the vertical piece to be straight for it to be rigid.

 

[DanielForest]

Straightening jig for the arms. Access constraints limit your options with a hammer and buck... it works just good enough

View attachment 10508

A little heat helps the metal relax a bit too
Eagle eyed viewers will notice a crack picture center. This was a result of whatever impact this arm took. Itll be ground out and welded up when I weld a strengthening plate to this side

Ben, while you boxed your control arm, you also removed the "bump". It was intented by Fiat to clear the bigger 5 speed transmission. That's why people planning to swap a 1500 cc with a 5 speed in the 1974-78 cars are told to change the (left) control arm. (Steve?) In practice, I don't think it is changing much, but be sure everything is safe when you put it back. You don't want your "amelioration" to cause damages to the tranmission end.

 

[Steve Hoelscher]

Ben, while you boxed your control arm, you also removed the "bump". It was intented by Fiat to clear the bigger 5 speed transmission. That's why people planning to swap a 1500 cc with a 5 speed in the 1974-78 cars are told to change the (left) control arm. (Steve?) In practice, I don't think it is changing much, but be sure everything is safe when you put it back. You don't want your "amelioration" to cause damages to the tranmission end.

Agreed. I trimmed the control arm for clearance. Had to because the additional travel caused even the 1500 control arm to hit the end of the transmission.

 

[DanielForest]

@Daniel
You hit the nail on the head. Ok now you got my consience going... should prob track down a second set of lock collars. Im wondering how to measure the thread size tho...

Ben, don't know if you are aware of it, but there are 2 types of collars. One is consisting of a pair of collars locking against each other (that's what you mentioned): first pic. But there is this other type with a small bolt (usually Allen) pushing on a rubber plug (to avoir marking the threaded tube). That's what is shown in the last pic, looking like some mud.

 

[Ben Louis]

Timely and usefull info as always. I have adapted my plans to account for the trans bump by creating a notch. If the box plate pieces look like they were one piece at some point that’s because ...ahem... well they were.

I mounted the arm half a dozen times re grinding where I needed to make sure it didnt hit anything in its arc.

Theres a bit of finishing to do but this is my overall solution

 

[Ben Louis]

Dan thanks for the tip about the rubber piece I was eventually going to drill and tap my collar instead of tracking a second one down

 

[DanielForest]

You are Lucky because 2 weeks ago, I didn't knew about the rubber. I just happen to be in the middle of dissassemble/cleaning my shocks. It makes a lot of sense for you. Even if you find the right size of collars later, you could always remove the screw and rubber and use the locking collar instead.. The only drawback is that it required more force to move since the rubber is keeping... rubbing, instead of a locking collar which will be easier to turn. But since its not something you will adjust often, that's fine.

 

[Dr.Jeff]

The coil-overs that I've had with a set-screw locking arrangement had a nylon tip on the screw (rather than rubber). Slides a little easier when adjusting things. The set-screw only needs to offer a little resistance against the shock body to deter rotation of the collar. You might even be able to use a nylon screw.

 

[Dr.Jeff]

poly bushings they will bind badly as the control arm moves through its normal range of motion. This is because the axis of the two pivots are not on the same plane. Thus the bushing have to twist and they don't do that very well. The best solution is the OE type rubber bushings.

Steve, interesting about the rear control arm bushings. Indeed the dis-similar axis of the two pivots will bind with the arcing motion [who says we'll never use geometry in real life]. For that matter even with stock bushings there will be resistance (to a lesser extent) as the rubber is 'squished' off-axis with articulation. But certainly the less compliant poly will be more so. A spherical/Heim joint should allow better off-axis motion, but it would not be practical for the street.

Over the years I've found "solid" or "firm" (e.g. poly) bushings/mounts are not very livable for everyday driving. And they can cause other problems. However some rubber bushings have too much movement and don't last long. In those cases the rubber is too soft and not enough of it. A couple companies have developed firmer duro rubber replacements with more material for certain applications. One good example is the up-rated rubber upper strut mounts for the X. That is a good compromise but the availability of such items is very limited.

 

[Ben Louis]

Spending my Sat finishing the control arms.

I welded over my tacks using a super hot setting (the highest my lil mig goes) so I ground back the welds to insure penetration and also cause it looks better

 

[Ben Louis]

Steve I now see why you cut holes to weld from the back side.