I agree with this. I just replaced mine with a Mevotech GK 6249 from Rock Auto. I'm on a budget and just picked the one that shipped from the same location as some other parts for my wife's car.

I compared it with the original on the car. It was the style with the big nut on the bottom like the photos shown above. While the drop is different, the arm is longer. So if you line up the mounting holes the hole that the center link mounts to is in the same location and the same plane. So different shape, same movement.

We'll see what if feels like tomorrow.

 

just so you guys know the GM part with the Nut Looking thing on the bottom..the upper arm part unscrews from the top..Larg thick threads..it runs down and bottoms out inside of the Nut looking part.you then back it out just enough. to allow steering to go full left or right..nothing special..shown bellow.. just replace with good USA made part..
(zink plate=rust Proof for life)

 

not quite following you? are you saying factory designs are available and made in the USA? Or are you saying replace the factory design with the new design shown in your golden box. What is made in the USA?

 

only replace if you need to..that pic above the one I posted is one of my photos. also in gold zink..and clear coated..
(don't do the clear coat)..takes away the luster of the zink..lol
that part is still sitting in my shop.. with only 20.000 miles on it..had it zink plated after taking the car apart..
was going to reuse it..but wanted to start with 0 miles.and all new parts..nothing wrong with the GM parts that came on the cars..

 

If one was to do both pitman and idler arm from the same manufacturer/brand would this still be an issue ?

 

Pitman arm isn't a wear item, so it isn't reproduced as far as I know

 

Ok. Thanks to this thread I am going with the McQuay-Norris FA1399 idler arm. Looks to be the correct geometry.

It comes with these two plastic inserts. What is their purpose?

Do they get installed here:


Or here:


???

 

The bore for the centerlink should be tapered to match the stud on the centerlink. If anything they'd probably be used on the mounting bolts to the frame rail.

 

Hi there! I drive a 91 Trans Am and have installed a Moog idler arm since 2016.
After I found this post, my workshop measured the positions concerned. All without the slightest deviation.
I cannot confirm this myth in my car.

 

So reading through the thread so the one mean identifier is the wide middle casting? Are there any proven good venders that sell the correct angle Idler Arm?

 

You won't know until you take the part out of the box and look at it. Lots of parts chains rebox inventory when brands change. That's one of the reasons vastly different parts can come out of the same box, and the same parts can come out of multiple different boxes. You can guess, but the moment of truth is when you have it in your hands.

If you're worried about it, buy local so you can check it out without paying return shipping if it's wrong.

 

Yes buying local for this part does make sense, so the only identifier is the wide casting?

 

I'd just compare the photos, or an original to the replacement. A casting isn't going to make it right or wrong.

 

I have to agree with sofakingdom's post a while back. I have all three examples including the threaded factory original. Recently studied side by side and each has the same drop, arm length, and sweep. Any of the three should work equally. While visually different, they are geometrically and functionally identical.

 

That is most likely a fair assessment. However, it's not worth taking the chance when you can just buy one that matches the original part.

 

of the 10 I've seen, every one with the thin casting was wrong (cast), and every one with the wide casting was correct (forged)

 

I haven't kept up on these 150+ posts. What is wrong with the thin-banded casting variety? I forget. Thanks.

 

They drop down farther than the stock part, and you may not have enough adjustment to get your center link horizontal.

 

Is this the correct arm for our cars?

 

That's the "incorrect" part. AC Delco is now rebranding the cast parts. You would have to get lucky amd get old stock for AC Delco to be correct IMO.

 

Looks about right.

Imagine a line between the 2 bolt holes, which is also the axis that the arm pivots on. Imagine a line parallel to that, passing through the center link ball joint hole. Imagine then, a line perpendicular to the 1st one, in the direction of the center link hole. Now imagine the distance along the 3rd line from the 1st line to 2nd (dimension "1"), and the distance from the 2nd to the center link hole (dimension "2").




If those dimensions are the same, and of course the bolt hole spacing, then it fits, works, and is "correct". Doesn't matter whether the "hinge" is long and the arm is less of a "Z", or if the "hinge" is short and the arm is more of a "Z".

High school geometry.

That leaves aside of course, the question of "thick" vs "thin". As to whether any given arm is "stronger" or otherwise "better" (perhaps better bearings or something) than another, is a WHOLE OTHER matter. Geometry however is geometry; fitment is not affected by "strength", or vice-versa.

This part is not "cast". It is forged.

 

 

 

"Research" photos from the other week.

 

First noticed the out of alignment chin spoiler!

 

Which three brands of Idler's are you using in your photo's?

 

Stock original June 1984
"McQuay Norris" FA1399 w/o packaging from Ebay
AC Delco from Rock Auto

Left to right.

 

Can't see any pictures.

 

Pics are in post #172

 

So the point to this thread is... nothing is wrong. They are the same. As clearly shown in the pics and basic hs geometry so****ingdom has shown above. So scrolling through, I see, and immediately think, I have the wrong part in my car. I'm sure many have thought the same. Now if they didnt scroll 150 posts down to see it's all hogwash... what I'm getting at is maybe people should do a little research before jumping the gun.
thanks saxondale for easing my mind.

 

thats imo the point.. we replaced the stock steering box with a Borgeson and we need to reallocate the idler am.. but thats not a problem at all. so, i think there is no wrong part but missing reallocation... maybe someone needs to change the thread title..

 

Wait, did I miss something?!? I thought earlier posts clearly showed a difference between the idler arms?

 

They are the same but different LOL...

 

There are differences, yes. But you can adjust it and then it works perfectly. So, yes, differences but no, not a problem.

 

I thought I remembered reading that WhiteDevilTA or someone couldn't adjust theirs far enough to get the centerlink level and tracked it down to the idler arm?

 

😉👍

 

With the moog, I could not get it adjusted even close to getting my steering linkage level with the control arms/ball joints. I switched to an AC delco which was a totally different part design, and magically everything aligned. Think what you would like based on the geometry being the same even though the parts have different cants to the arms, but one worked for me, the other didn't. I was merely giving a heads up to an issue I had personally.

 

For sure... not being able to adjust it to the right place is DEFINITELY a defect; but the straight vs Z or "drop" shape is not, in and of itself.

 

Anyone have any success with Pro Forged Idler Arm?

 

I'm in the process of putting one on now. I'll report back once I have everything in or you can check it out in my build thread.
https://www.thirdgen.org/forums/memb...-trans-am.html

 

ProForged idler arm lined up fine.

 

I'm assuming it's the angle of the picture but to me it looks like the driver side is slightly higher than the pass. side. How did you determine that they were even?

 

Good question. Since the ground I'm working on is uneven I tried to measure off the a-arm pivot bolts. That proved to be challenging so I used a straight edge aligned with the bottom of the a-arm extending out to the inner tie rod which came out to 3mm each side. Then I eyeballed it and called it good for now.
There's still up/down adjustment potential in the frame slots from where its currently at.

 

Awesome! That's what I was hoping to here. I've been on the fence about Moog vs Proforged for my front end rebuild.

 

I found the ProForged kit to be very well made with quality components. Their customer service was fantastic too...very friendly and willing to talk shop.

 

I have the proforged idler arm in my 88 with all other steering parts original factory parts from 88 (just 20k on the odo), and I have the complete proforged kit in my 92. I really love the proforged parts, they are very well made and everything fitted perfect, plenty up/down adjustment potential on both cars for the idler arm.

 

Just a 2020 warning.
some guys have been telling me the new AC Delco Idler arm is now WRONG for our cars.
Looks like they changed the design.
I assume to be used in another platform.

Proforged seems to have the right idler arm geometry

 

Where you able to confirm that this fits your car? I had ordered one from Amazon and it just arrived.

 

That one works fine. See post #170 above wherein the geometry is drawn out fully.

The vertical distance, along the pivot from the bolt holes to the center link point, is correct (in that it matches an original); and the length of the swinging arm from centerline of the pivot to center of the hole, in a direction perpendicular to the pivot, is correct. So yeah... geometry is geometry. Pretty dependably.

I have a feeling that WhiteDevil, and maybe others, got hold of one(s) that had the wrong pivot or some such, such as with the bolt holes too far up or down along the fixed piece; or, where an arm of one type got assembled to a pivot intended for another type; or some similar manufacturing defect. He's not stupid, and knows what he's doing; no way would call him a liar or tell him he's full of s*** about something like that. Rather, I'm saying that the issue is, that he misattributed the cause of an observed fact. Which of course that relationship being wrong WOULD DEFINITELY be a malfunction: if the relationship of the bolt holes to the center link hole is WRONG, then the arm is WRONG, because it CANNOT then be installed onto the car in such a way that the center link is level. On the other hand, if that relationship is RIGHT, then the arm is RIGHT, regardless of whether it accomplishes that by the pivot shaft being relatively long and the arm relatively "straight", or the pivot shaft being short and the arm being more of a "Z".

 

Maybe he had a different or incorrect pitman arm installed?