OEM part number; original vs replacement

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Schurkey

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It was not on an alignment rack.

as a part of the saftey, the alignment was checked
No, it wasn't. No alignment rack, no alignment check.

Some ya-hoo may have eyeballed the various parts including the tire treads, and seeing no obvious loose parts except the one he removed 'n' replaced, and no uneven tire wear, told you the alignment was "ok".

the alignment is nuts on...
...I have successfully done old school alignments on my vehicles in the past, but in those intances, it was because I was replacing tie rods - they are perfect right now.
You're passing this off as if the alignment angles were "perfect", including toe. There's no guarantee that's true.

I could realign it myself, but what would be ALOT less work is to find an original design center link (GM or aftermarket) and re-replace it with the same design part that the truck originally had - that would be two bolts, and one nut.
That's what I'd really like to do.
Good luck replacing a perfectly-good "revised" idler arm with a perfectly-good "original" idler, and having that change the clocking of the steering wheel.

You clearly don't care about verifying camber or caster; or even verifying the amount of toe, so long as the wheel is straight. What is so hard about turning one tie-rod sleeve a quarter- or half-turn clockwise, and the other one the same amount counter-clockwise? Whatever it takes to straighten the wheel?

Wild Guess with no evidence: The old idler arm was partly-worn-out during the last actual alignment, or the idler arm has a little play in the bolt holes where it attaches to the frame. The tie rod ends were adjusted to straighten the wheel based on the previous idler arm positioning the end of the center link. Now you've got the center link in a slightly different position due to the idler not being sloppy, or (less likely) not tilted exactly the same as the previous arm, and you need to adjust the tie rod ends to match.
 
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1998_K1500_Sub

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What is so hard about turning one tie-rod sleeve a quarter- or half-turn clockwise, and the other one the same amount counter-clockwise? Whatever it takes to straighten the wheel?

I've been wondering the same thing since this post originated.

The alignment wasn't touched because everything else was perfect... except the steering wheel doesn't point straight when the wheels do.

I'd like to remedy this.

OK, so the steering wheel's off but everything else is acceptable. Give the adjusters a twist, in equal and appropriate "turns" on each side, to maintain toe but straighten the wheel.

Done.
 

unruhjonny

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It seems as though I had a misunderstanding that was increased with the very first reply I received.

This post is what got me to re-look into this:
1st design 26016461* The original was a 2 piece design, I believe the revised design is of a non-seperable one piece design. both with 2 hole frame bracket.

2nd design 26059031 does not apply and is not the superceeded part as it's for 93 up and has a 3 hole mounting flange. A completely different design that won't bolt up to your frame.

This one really rang with me, so I looked into it:

This is the design of the part #26016461 for 1988-1992 trucks:

You must be registered for see images attach


This is the design of the part #26059031 for 1993-2000 trucks (as per post #2):

You must be registered for see images attach


These are CLEARLY not interchangeable, so although they do qualify as first design and second design, they don't fit within the context of my original query.
So that right there was a HUGE derailment from what I was asking.

I could cite many examples where GM revised a part so that functionally it worked to replace the original design part, but while the changed part was first installed on later model year vehicles, it then later became to the superceded/replacement part for the earlier vehicles;
That is the type of "first design vs second design" part that I was inquiring about.

To the best of my recollection, the mechanic told me that the design of the replacement idler arm wasn't exactly like the one he removed.
To be quite clear, camber and toe are perfect.
You do not need to put a vehicle on a rack to check this - racks are a newer innovation, and I can assure you that alignments can be done without any newer tools;
This replacement idler arm has in some way geometrically deviated from the part removed from my truck and has pulled the center link to one side, making the steering wheel not straight when the vehicle is tracking straight.

I stumbled on the following discussion last night when looking further into this, and believe it has bearing here;
It cites an example where an aftermarket idler arm does not actually mirror OEM specs:

BEWARE MOOG IDLER ARMS
After some back and forth which seems to make a pretty clear/convincing argument that (in this case the third gen F-body) idler arm is often manufactured incorrectly (maybe due to quality control at different facilities - who knows) this is posted:
Just spoke with a technician at moog and explained to him the issue with their idler arm. I told him I have pictures and everything showing how it's a wrongly designed part, and he basically told me the cars are too old for them to bother redesigning it. I asked him if there was anybody higher up that I could e-mail the pictures too and that it was pretty apparent from them that it was incorrect, and he said that they wouldn't do anything anyways...

It doesn't seem to be a huge stretch to think that the part which was installed on my truck, although a correct replacement part, has something off about it which alters the geometry where it should connect to the center link compared to the GM part removed from it;
So, my initial query where I stated that:

(he) told me the design had changed from the original part
I had interpreted that as to understand that the design had changed.

Then when the first reply to my query was:
We did a design change on those and the 26016461 has been discontinued and removed from all aftermarket and OEM sources since 2002. It was replaced by the updated design of the 1993-2000 # 26059031.
I saw that as an affirmation of sorts - hopefully some of you may understand this.

The following are the part numbers are ones I have found, which may or may not indicate a revision to the original designed part (sometimes GM has seemed to arbitrarily renumber a part; I have understood that sometimes this is an indication of using a different supplier, while other times something has changed in the design of the part):
26016461
12387682
12471302
88911352

I do not know if all those parts are put side by side (these are I believe all GM numbers), if they would be exactly the same - but they do indicate a change of some sort.

I still hope to remove this aftermarket idler arm for a GM part which should hopefully prevent me from having to screw with my alignment.

If a member of the moderation or administration team wishes to delete this discussion all together I will completely understand.
 
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Hipster

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There's more to an alignment then caster, camber, and toe, and yes you can get really close mechanically measuring these as well as LBJ setback. Not so much with Steering axis inclination angles, included angles, and turn radius. Dealing with a Short arm/long arm suspension system is much more involved then throwing a set of tie rods on a vehicle where toe is likely the only adjustment.

I'll say it again, if the new idler was short or longer then the original from pivot point to pivot point it would have shown up in the toe setting. If the the new ider arm was not the right height and tilts the center link from one side to the other it would have also affected the toe setting. Either situation can also induce some bumpsteer. So either the methods or accuracy of how whatever this alignment check consisted of is in question. I say this without a doubt as I've had a lifetime of diagnosing collision damaged suspension. It would have most certainly showed up and whatever perfect alignment you think you have after this idler was installed likely is not.

To correct one of you earlier statements, aftermarket parts are loosely based on Gm specs. Some are better than others and even getting the original oem part might not preclude you from having to have an alignment done.
 
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unruhjonny

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Thanks for your reply, I will remember this when it warms up outside, and I revisit the steering components.

This guy is a fourty plus year career mechanic (he was supposed to have retired over a decad ago!) - I have absolute confidence in his assessment of the alignment.
 

Hipster

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Thanks for your reply, I will remember this when it warms up outside, and I revisit the steering components.

This guy is a fourty plus year career mechanic (he was supposed to have retired over a decad ago!) - I have absolute confidence in his assessment of the alignment.
Believe what you want to believe. If there was an issue with the idler it's going to show up in the alignment numbers without exception and all is not perfect.

Good luck to you.
 
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