[68lemans462]

How can I identity the front and rear of these control arms? I know some a body arms had holes in top but these do not. Going to box these arms and want to make sure I'm doing it the right way. They look symmetrical to me..

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[Mike Davis]

Those look like the ones with the factory sway bar holes. The holes go towards the rear of the arms. So basically the top of your picture is the rear of the arms.

[68lemans462]

Originally Posted by Mike Davis

Those look like the ones with the factory sway bar holes. The holes go towards the rear of the arms. So basically the top of your picture is the rear of the arms.

Well, ACTUALLY these are the stock set that came on the car (no sway bar). I replaced the bushings and added a sway bar in my younger days (20 years ago) and Im not 100% sure I got these in the way they came out. Just wanted to double check before we weld these up over the weekend as I'm much more anal than I used to be. The holes might be in the right place, they might not.. Any other way to identify the front/rear of these arms assuming the holes arent there??

[OG68]

Without holes it doesn't matter which way they go in. But as mentioned above, the holes go to the rear.

[68lemans462]

Sounds like they are symmetrical as they appear to be. Thanks for the info guys.

[Tom Vaught]

Early ones can go in either way.

Tom V.

[tjs72lemans]

Late ones can go either way too. When I did my 72 I wasn't sure. But, they were symmetrical.

[Tom Vaught]

Originally Posted by tjs72lemans

Late ones can go either way too. When I did my 72 I wasn't sure. But, they were symmetrical.

I strongly Disagree.

I am looking at one of my Factory NOS Lower Control Arms with the NX tags still attached on the arm.

The arms may be identical as far as being switched from Side to Side but they are not able to mount the sway bar when they are mounted in the opposite position from stock. Rear to front

Here are the dimensions on the arm: See picture below and enlarge it by clicking on the image.

24 - 7/8" long (end to end)

Lower Arm Mounting holes (to the frame/axle) are 1.5" from the outer edge of the arm.

"Front Sway Bar Mounting Hole" is approximately 12 7/8 inches from the front arm end metal and 12 inches from the rear arm end metaL. So that hole is really NOT in the center of the arm.

The "Rear Sway Bar Mounting Hole" is approximately 6 inches from the REAR arm end metal.

The Sway Bar mounting (center to center of the bolt holes) dimension is: 6 inches.

There is no way you could mount the Pontiac Rear Sway Bar in the holes if the arm was reversed unless you had a non factory sway bar system.

That being said, possibly a frame mounted sway bar system might allow the bars to be swapped end for end but it would not be in the factory location.

Tom V.

See Image attached.

[Tom Vaught]

One other comment.

If you look at the Picture attached in Post #8, you will see that the Trailing Arms have a special feature built into them during the fabrication process. The plates welded on the bottom of the Lower Control Arms have a "Dropped Reinforcement" where the reinforcement is made in a shape like this " -U- " except that the flat surface portion is at the top on the "U".

Can't duplicate this image with the PY Software easily.
The "U" portion extends inside the arm to support the walls of the Lower Trailing Arms so that they do not collapse inward when you tighten the sway bar fasteners.

So even if you tried to drill the holes in the side of the reinforced arms (in the reversed positions) the walls would collapse over time due to the lack of the internal " -U- " reinforcement.

Tom V.

[389]

You want the ring side of the bushing to go towards the center of the car.. But if you tack each bushing you don't have to worry. I would tack them.
Those factory arms were designed to be flexible and bend, driving on the street you need that flexibility. Welding them up was only meant for drag cars that never see the street. John DeLorean was pissed when Pontiac offered the rear sway bar option on the GTO because he knew it binded up the four link suspension..

Frankly with the superior adjustable rear control arms company's like, Spohn, SC&C and UMI sell why bother with them. They flex and twist on acceleration. There just not worth it.. Having Delrin spherical bushings is light years better then these old control arms..

You never want the sway bar attached to the control arms on a four link..

[Formulajones]

That's where I would disagree. Factory did it for years and it works fine.

We have 2 A-bodies here that we street drive and drag race. One with a factory rear sway bar and factory rear lower boxed arms. The other, I boxed the arms myself and added a factory rear bar.

Both cars drive perfectly fine on the street. Actually I'd say out of the dozen cars here, they are the best riding cars out of the bunch and the most comfortable.

They also cut 1.5 60 foot times on a DOT tire and 4,000 lbs race weight.

Not that I'm against the aftermarket bars, they are nice. I just find this method works fine, saves a few bucks, and looks bone stock when peaking under the car.

I do however have tubular upper arms on both cars that are adjustable to move the pinion angle around.

[Kenth]

To add to Tom V´s comment i took a picture of my set rear lower control arm inserts, which are available from Ames, part-# 5139CB.

[Tom Vaught]

Originally Posted by 389

Those factory arms were designed to be flexible and bend, driving on the street you need that flexibility. Welding them up was only meant for drag cars that never see the street. John DeLorean was pissed when Pontiac offered the rear sway bar option on the GTO because he knew it binded up the four link suspension..

Did not realize that I had screwed up on the lower rear arms and sway bar for 49 years. My convertible rode just fine on the street during that time.

Probably because the convertible had a boxed frame and no roof, right??
LOL.

As soon as John Delorean went to Chevrolet in 1970, why did he not get rid of the rear sway bars on the Chebby vehicle line if HE was so against them?
Maybe because Zora Duntov proved to him that he was full of Chit.

Tom V.

[Scarebird]

I installed one on my first car, a 69 Cutlass S using formed blocks of hardwood inside the arms. Handled better. That said, how many non-GM vehicles used that style of bar for a 4 link? I am thinking it's main virtue was cost.

My 71 will have a different bar replacing the OEM style one.

['ol Pinion head]

Originally Posted by Kenth

To add to Tom V´s comment i took a picture of my set rear lower control arm inserts, which are available from Ames, part-# 5139CB.

The inserts have been stamped out by several entities since the late 80's. The first small company having inserts stamped out was only doing so to make inserts for their stock of clean used lower control arms.

Anyone can measure the thickness of the inserts that have been avail over the last dozen years, they are of a considerably thinner guage steel than was originally used by GM on original '64-65 & '66-72 boxed lower control arms.

[Tom Vaught]

I would second that comment, OPH!

Tom V.