Idler Arm question

Blmeis

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So engine from my 73 vert is still at rebuild shop so decided its a good time to remove the gear box and send back for rebuild hoping to fix loose steering. At the same time I'm replacing the idler arm. I'm a little confused though. After looking at multiple websites for idler arms, in the details it states "for manual steering". I have power steering. Is there a different idler arm for a 73 mustang with power steering or are these interchangeable?

 

Stanglover

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So engine from my 73 vert is still at rebuild shop so decided its a good time to remove the gear box and send back for rebuild hoping to fix loose steering. At the same time I'm replacing the idler arm. I'm a little confused though. After looking at multiple websites for idler arms, in the details it states "for manual steering". I have power steering. Is there a different idler arm for a 73 mustang with power steering or are these interchangeable?
That is a good question, are they the same or different for PS v MS? Nobody has been able to tell me either. I bought part #3355-1 from NPD. BUT I had to hand slot the top hole considerably. The angle of the arm is different to the original, but the end point is the same if you get what I'm saying. I read that the top hole may need to be slotted on some applications. Anyway it fitted OK and the drag link lined up well. I too am rebuilding my PS box and overhauling the steering completely. I won't know if that idler arm is good until I get the car back on the road in Spring. If not, I guess I'll be changing it again.

 

72HCODE

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the arm and bracket is different between the manual and power steering.

the bracket has a slightly different kick out and the arm itself has a shallower angle and is longer on the power steering version.

when i replaced mine i made sure the replacement part looked 100% the same as the original i had.

now you could use either on the car but if the car was on a lift and you looked at the geometry of the steering cross bar it would not be straight.

the angle of radius would be different between the driver and passenger tire when turning.

an alignment shop would not pick that up because they never test for tire angle left to right full lock.

it would pass all the camber, caster, toe measurements. i guess if you raced the car you would notice a difference in steering left to right in curves.

now i did mine years ago and it was a FORD NOS part, so i matched part numbers and compared my original to the new one.

 

Blmeis

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Great feedback! I will continue to research and look for a part that is, like you said, "looks 100% like the original". I really want a 100% OEM part and don't want to risk screwing an aftermarket part up because I need to "modify" it to make it fit.

 

Stanglover

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Great feedback! I will continue to research and look for a part that is, like you said, "looks 100% like the original". I really want a 100% OEM part and don't want to risk screwing an aftermarket part up because I need to "modify" it to make it fit.
I forgot to mention that my original idler arm was for manual steering. I added PS a couple of summers back and I didn't notice any problems in steering control. However I do agree that it is best to get what's right. I have nothing to compare the PS idler arm to, so like I said, I may be changing it again. If someone knows the exact part number and supplier for a PS idler arm, please let us know. As Blmeis said, they all seem to be listed as for Manual Steering!!



That's interesting Don, Worth looking into.

The one I bought from NPD is listed as PG (professional Grade) and has grease fittings on both bushings.

 
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Blmeis

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Stanglover, I think I'm going to try the one Don suggested from Ohio Mustang. I'll provide feedback after I get the product (compared to original), when I get the product on the vehicle (fitment), and then again after I take her for a test drive. No need to wait for Spring here in TX, just need my engine back first!

Brian

 

Stanglover

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Stanglover, I think I'm going to try the one Don suggested from Ohio Mustang. I'll provide feedback after I get the product (compared to original), when I get the product on the vehicle (fitment), and then again after I take her for a test drive. No need to wait for Spring here in TX, just need my engine back first!

Brian
Lucky bugger!!

Yes, please let us know how it compares to your original. I took a look at mine, but was still a bit too cold in the garage, despite a record high temp today, to spend any time crawling into the engine bay.

Keep in touch on this as others will no doubt be interested.

Geoff.

 

Stanglover

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I took a little time to compare my two idler arms, the original MS and my aftermarket USA made replacement. The math shows that they are both very similar. I'll admit without removing the new one, it was a bit of a guess as to accurate dimensions. Here's what I found: the axis line through the centerline of the mounting bolt holes to the axis line through the centerline of the draglink (D/L) bushing measured almost the same at 5.25" + / - and are parallel to one another . The old bushing in the MS arm is badly worn, so I can't be sure if the my centerline measurement of 5.315" is accurate, but close enough for this. The top surface of the D/L bushing insert to the center of the bottom hole in the mounting post looks to be the same. Therefore it matters not what the lower bushing dimension ( location) to the center of the bottom hole on the mount post is, the arc scribed will be the same. This means that there will be no effect on the steering. If I had access to CAD I could illustrate what I'm trying to explain, so I hope people can make sense of this.

Bottom line is as long as the centerlines are the same, the arc travelled will be the same. I just know someone will question my "theory" , but I wanted to do this for myself mainly to satisfy my own curiosity.

Geoff.

NOTE: I added " and are parallel to one another"

 
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Stanglover

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I understood what you were saying

but I are a genius ;)
Wow, I could barely understand what I was writing!!

If I were a genius, I wouldn't have had to work 45 years to figure that out.

Thanks for the feedback Jeff.

 

Blmeis

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So sorry for the long delay. I forgot I was gonna post pics to show difference between my old idler arm and new. This would have probably been more helpful if I would have compared them before putting the new one on vehicle.

Anywhoo, to late for that so hope this helps a least a little!

IMG_20160227_072957473.jpg

My replacement part is part #3350G(IDLER ARM, 1971-73 Mustang All, M/S & P/S) from California Mustang. However, I got the arm over 30 days ago. Both the price of the arm(I paid $43.95-free shipping, it's now $59.95) and the part picture have changed on the website. So side by side...looks like new arm isn't as angled as original.

IMG_20160227_073309075.jpg

Also nut on bottom is gone and has been replaced by the grease plug. Seems to work fine. I just took off the old, set the new in the same position, lined it up under the car and it fit in place easily. Tightened down and good to go. My engine is still not back so haven't driven it yet. I will have to post update later.

 

Stanglover

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So sorry for the long delay. I forgot I was gonna post pics to show difference between my old idler arm and new. This would have probably been more helpful if I would have compared them before putting the new one on vehicle.

Anywhoo, to late for that so hope this helps a least a little!

My replacement part is part #3350G(IDLER ARM, 1971-73 Mustang All, M/S & P/S) from California Mustang. However, I got the arm over 30 days ago. Both the price of the arm(I paid $43.95-free shipping, it's now $59.95) and the part picture have changed on the website. So side by side...looks like new arm isn't as angled as original.

Also nut on bottom is gone and has been replaced by the grease plug. Seems to work fine. I just took off the old, set the new in the same position, lined it up under the car and it fit in place easily. Tightened down and good to go. My engine is still not back so haven't driven it yet. I will have to post update later.
Okaaaay! that 73 stuff is different to 71's, BUT it is the geometry that matters more than the shape. Re-read my reply 2/04/16. As long as the radial distance, centerline to centerline, and the top of the drag link bushing is at the same height relative to the bottom bolt hole, then it matters not the angle of the arm is. The idler arm I used did have fitment issues with regard to the top bolt hole needing to be slotted, which I knew about. The US manufacturer screwed that up, but apart from that it is a quality part and has grease fittings on both swivels joints. I'm in the same boat here, until spring and I get my engine back, I can't test it either, but I don't anticipate any issues. I did get my power steering box rebuilt yesterday, so that's another job just sitting, waiting.

I'm sure you'll be ok with what you have. It's good to know that there are other options for replacement idler arms out there.

Geoff.

 

jbojo

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So sorry for the long delay. I forgot I was gonna post pics to show difference between my old idler arm and new. This would have probably been more helpful if I would have compared them before putting the new one on vehicle.

Anywhoo, to late for that so hope this helps a least a little!

My replacement part is part #3350G(IDLER ARM, 1971-73 Mustang All, M/S & P/S) from California Mustang. However, I got the arm over 30 days ago. Both the price of the arm(I paid $43.95-free shipping, it's now $59.95) and the part picture have changed on the website. So side by side...looks like new arm isn't as angled as original.

Also nut on bottom is gone and has been replaced by the grease plug. Seems to work fine. I just took off the old, set the new in the same position, lined it up under the car and it fit in place easily. Tightened down and good to go. My engine is still not back so haven't driven it yet. I will have to post update later.
Okaaaay! that 73 stuff is different to 71's, BUT it is the geometry that matters more than the shape. Re-read my reply 2/04/16. As long as the radial distance, centerline to centerline, and the top of the drag link bushing is at the same height relative to the bottom bolt hole, then it matters not the angle of the arm is. The idler arm I used did have fitment issues with regard to the top bolt hole needing to be slotted, which I knew about. The US manufacturer screwed that up, but apart from that it is a quality part and has grease fittings on both swivels joints. I'm in the same boat here, until spring and I get my engine back, I can't test it either, but I don't anticipate any issues. I did get my power steering box rebuilt yesterday, so that's another job just sitting, waiting.

I'm sure you'll be ok with what you have. It's good to know that there are other options for replacement idler arms out there.

Geoff.
Just saw this thread. I ran into the same problem with my build. There is a slight difference in 73.

 

secluff

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The idler arm for 71-73 M/S & P/S is the same. By 1975 the idler arm listed for the 73 (D3ZZ-3355-A) had replaced the D1ZZ arm listed for the 71-2. You'll notice some of the aftermarket arms will have some different angles. But as Stanglover very well explained the centerlines and mounting hole location's equate to the OE arm. So those on this site that are at Genius level, such as Jeff73Mach1, (LOL) understood Stanglover's post. For all others, "The Angle of the Dangle" is the same!!

Found an old invoice in a file I keep for my Pewter Mach 1. On 11/11/77 I paid a whopping $17.63 for a D3ZZ-3355-A ($16.95 +.68 tax). I remember complaining about those #@$&!" expensive replacement parts!!

 

Stanglover

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The idler arm for 71-73 M/S & P/S is the same. By 1975 the idler arm listed for the 73 (D3ZZ-3355-A) had replaced the D1ZZ arm listed for the 71-2. You'll notice some of the aftermarket arms will have some different angles. But as Stanglover very well explained the centerlines and mounting hole location's equate to the OE arm. So those on this site that are at Genius level, such as Jeff73Mach1, (LOL) understood Stanglover's post. For all others, "The Angle of the Dangle" is the same!!

Found an old invoice in a file I keep for my Pewter Mach 1. On 11/11/77 I paid a whopping $17.63 for a D3ZZ-3355-A ($16.95 +.68 tax). I remember complaining about those #@$&!" expensive replacement parts!!
I'm glad someone understood what the heck I was trying to explain!!. I'm far from Genius Level, about the only part of math I was any good at was geometry and trigonometry. It is all about the angle of the dangle and the length of the dip-stick.

Geoff.

 

secluff

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The idler arm for 71-73 M/S & P/S is the same. By 1975 the idler arm listed for the 73 (D3ZZ-3355-A) had replaced the D1ZZ arm listed for the 71-2. You'll notice some of the aftermarket arms will have some different angles. But as Stanglover very well explained the centerlines and mounting hole location's equate to the OE arm. So those on this site that are at Genius level, such as Jeff73Mach1, (LOL) understood Stanglover's post. For all others, "The Angle of the Dangle" is the same!!

Found an old invoice in a file I keep for my Pewter Mach 1. On 11/11/77 I paid a whopping $17.63 for a D3ZZ-3355-A ($16.95 +.68 tax). I remember complaining about those #@$&!" expensive replacement parts!!
I'm glad someone understood what the heck I was trying to explain!!. I'm far from Genius Level, about the only part of math I was any good at was geometry and trigonometry. It is all about the angle of the dangle and the length of the dip-stick.

Geoff.
Yep, it seems like it takes a village for all of us to figure these cars out. After graduating many years ago, I think I've finally figured that I did best in study hall and lunch!!

I'm sure the Angle of the dangle is probably fine, just don't let the 429 guys bait you into a dip stick comparison!!! :whistling:

 

Stanglover

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The idler arm for 71-73 M/S & P/S is the same. By 1975 the idler arm listed for the 73 (D3ZZ-3355-A) had replaced the D1ZZ arm listed for the 71-2. You'll notice some of the aftermarket arms will have some different angles. But as Stanglover very well explained the centerlines and mounting hole location's equate to the OE arm. So those on this site that are at Genius level, such as Jeff73Mach1, (LOL) understood Stanglover's post. For all others, "The Angle of the Dangle" is the same!!

Found an old invoice in a file I keep for my Pewter Mach 1. On 11/11/77 I paid a whopping $17.63 for a D3ZZ-3355-A ($16.95 +.68 tax). I remember complaining about those #@$&!" expensive replacement parts!!
I'm glad someone understood what the heck I was trying to explain!!. I'm far from Genius Level, about the only part of math I was any good at was geometry and trigonometry. It is all about the angle of the dangle and the length of the dip-stick.

Geoff.
Yep, it seems like it takes a village for all of us to figure these cars out. After graduating many years ago, I think I've finally figured that I did best in study hall and lunch!!

I'm sure the Angle of the dangle is probably fine, just don't let the 429 guys bait you into a dip stick comparison!!! :whistling:
Too funny Steve!!!

 

roadwarrior

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Just went thru this exercise for my 71 convertible, pics of the original power steering idler and the Moog K8118 manual steering idler are below. I slotted the hole closest to the joint to raise the assembly up as much as I can. Also, the factory PS arm is straight mounted and the new one has an offset. Finally, there is a difference about a 1/2"-3/4" difference in locating height for the center link, the arc of motion the arms swing thru look to be the same however. I loosely assemble the new pitman, new idler and cleaned original center link and lightly snugged everything up and it all went together without any complaints. Is it binding? Probably some, has to be due to the minor alignment differences of the assembled parts, but I was not able to feel it. Gotta be better than the hammered parts I removed.

Pics...







elongated slot to the bottom



offset



I will keep the old idler and see what bushings I can find to rebuild it. May swap it back if I run out of other projects.

Also, as a note, 16+ years ago I converted my manual steer 71 fastback to power and didn't switch the idler, didn't even know that there was a difference until I read up about it last year on here. Never noted any problems, not saying that it is a correct install with the wrong idler, but I haven't had any issues.

Best regards,

Tom

 
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