Moog Idler Arm, Holes don't match and Geometry

[andy72]

So Yes, I've read all of the posts on the different looks and shapes of the different idler arms available.

I got the Moog #K8118 from Rock Auto. I have seen this part mentioned in one of the posts.

It is Moogs correct part for this application.

1st of all, the holes aren't the correct spacing to just bolt it in.

I read where the $175 dollar NPD #3355-1a didn't bolt right in and had to had its top hole slotted.

2nd, when I use the top bolt to mount the idler arm, (the bottom hole doesn't line up and would have to be re drilled thru

the car) the centerlink attachment point will be about 3/4" lower than where it was with the idler arm that was

on the car.  See pics. Centerlink attachment point on my old idler arm is 11 1/8" from measure point. With the new Moog idler arm it is 10 5/8" from same point.

The new Moog puts the centerlink attachment point to the idler arm about 3/4" lower than the idler arm that was on the car. I suppose this is minor and when the alignment is done all will be good?

I really don't want to deal with returning a part. 

Is a little modification all that is needed to move forward?

Or, the existing idler arm actually feels nice and tight.  It is not loose at all? Should I just reuse it?

I hate to drill holes thru car because a replacement idler arm doesn't have the same hole spacing as factory!   frustrating...

And the geometry is different... A lot of after market products have little tweaks that make them more up to date

or modern than the "old stuff" .  Is this the case?

Got new Moog upper and lower control arms, spring perches, all 4 tie rod ends, rebuilt variable ratio steering box, strut rod bushings,

shocks, but I can't get an idler arm to just simply work?  DOH

What do you think?

 

[cwalker509]

I just spent half hour looking thru my credit card charges. I bought this part as a clearance item from world wide auto supply I think? It is OEM. I got idler arm and pitman arm for $64. This was a few months ago. Their website is not good (or I looked at wrong website). I dunno how I found it but some internet sleuthing may be helpful? If you would like I can try calling them on Monday to confirm it was them I ordered these parts from if you would like.



4d4 dice

 

[Hemikiller]

Ran into this problem years ago, ended up rebuilding my factory arm with new bushings.

 

[Bentworker]

You probably already saw this if you searched…

https://www.7173mustangs.com/thread-idler-arms-anyone-use-a-rare-parts-20250?highlight=idler+arm

 

[Stanglover]

That darn Idler arm again!

All I can say is the one I bought from NPD that needed the TOP hole slotted upward is probably the best you find aftermarket. It matches the important geometry even though it doesn't look exact. I've had this on my car for a few years now without any issues whatsoever. Drag link lines up perfectly and no issues aligning the front end.

Here is a sketch I made to illustrate what is important. Also read the posts linked by Bentworker.

Also see #9 in this post 

https://www.7173mustangs.com/thread-idler-arm-question--25289

Idler arm.pdf

 

[cwalker509]

That darn Idler arm again!

All I can say is the one I bought from NPD that needed the TOP hole slotted upward is probably the best you find aftermarket. It matches the important geometry even tough it doesn't look exact. I've had this on my car for a few years now without any issues whatsoever. Drag link lines up perfectly and no issues aligning the front end.

Here is a sketch I made to illustrate what is important. Also read the posts linked by Bentworker.

Also see #9 in this post 

https://www.7173mustangs.com/thread-idler-arm-question--25289

I will have to remember this.  I bought them to put away.  Not sure mine needs to be replaced.  One of the handful of parts that did not come off the car. Thx!

 

[andy72]

I have an email request in to the MOOG tech guys to see what they can tell me.

I'm not holding my breath...

 

[Hemikiller]

The Moog arm is completely wrong, no idea who thought that could work on a 71-73. You can't make it work either, as the drag link end will be in a different plane than the pitman arm, which will place the whole assembly in a bind and eventually cause a failure. Put it back in the box and return it.

The original you show in the pic can be rebuilt, you'll need Moog bushings K8094 (bracket end) and K8103 (drag link end). The pair costs under $20 from Rock Auto. They are easily installed with a couple of sockets and a bench vise - that's how I did mine. You may find references to M/S only on the bushings, but Ford only had one idler arm for both MS and PS in 71-73.

https://www.rockauto.com/en/moreinfo.php?pk=203251&cc=1132692&jsn=3232

https://www.rockauto.com/en/moreinfo.php?pk=203247&cc=1132692&jsn=3235&jsn=3235

FWIW - I went through this exact exercise back in the 90's, and again in the early 00's when I did my present 71. There wasn't then an aftermarket arm that would work. Luckily I had an original and was able to rebuild it.

$20 to have a rebuilt original part.

*** EDIT***

Found this arm at CJ's for $70 - looks correct, but it's CJ's so you may not get what's in the picture.

https://www.cjponyparts.com/idler-arm-1971-1973/p/H18750/?gclid=Cj0KCQjwuZDtBRDvARIsAPXFx3C_Zf2-A0_L05YSl2xulSybpsBLxTQaHW3LVaSDNA2mW6Xfabd_tu4aAlMMEALw_wcB

 

[73' mach 1]

Not sure which brand I got from Summit but I just replaced mine yesterday along with the rest of the steering linkages.

 

[andy72]

73'mach 1, you didn't mention if it had the same critical dimensions as your o.e.m. stock unit...

Hemikiller, thank you so much for the info..  I was really wondering what to do.

I just reread the post from Stanglover from 2-4-16.  He mentioned that if the center line of the mounting bolts to the center line of the

hole is 5.25", that the arc would be the same, and therefore ok?  Unless I didn't understand.

I was checking it out on the car today.  When the idler arm end of the drag link is down lower than that of the pitnam arm, it doesn't

look right because of course the center section is slanted down.

Hemikiller, again thanks.  I'll send back the Moog unit, get the bushings, and go that direction.

 

[Stanglover]

Not sure which brand I got from Summit but I just replaced mine yesterday along with the rest of the steering linkages.

 That looks pretty good. The drag link is parallel to the frame and looks to be level.

If the frame bolt centerline to the drag link bushing centerline is 5 1/4" or thereabouts, you should have no problems.

Geoff.

 

[Stanglover]

73'mach 1, you didn't mention if it had the same critical dimensions as your o.e.m. stock unit...

Hemikiller, thank you so much for the info..  I was really wondering what to do.

I just reread the post from Stanglover from 2-4-16.  He mentioned that if the center line of the mounting bolts to the center line of the

hole is 5.25", that the arc would be the same, and therefore ok?  Unless I didn't understand.

I was checking it out on the car today.  When the idler arm end of the drag link is down lower than that of the pitnam arm, it doesn't

look right because of course the center section is slanted down.

Hemikiller, again thanks.  I'll send back the Moog unit, get the bushings, and go that direction.

 Andy72, Referring to my "sketch", as far as I could determine, if dimensions "X" and "Y" on the original Ford part match the new part, then all should be good. And yes, you did understand what I was trying to get across.

Replacing the bushings may be your best bet overall. I actually think I'll order those and re-bush my old original even though it was a M/S. I ran that with the power steering upgrade I did for a couple of years without any issues whatsoever.

Geoff.

 

[andy72]

Thanks, really appreciate the info.

The Moog idler arm is a terrible fit for this car.

The hole spacing isn't even close.  Not just "elongate" a hole.

Returned the Moog and have the bushings on the way to rebuild...