'67 Idler Arm vs. '68

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JD Erisman

JD Erisman

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The topic of swapping a 67 to 68 K member, swapping 67 idler arms for a later version etc... has been beaten to death but I did numerous searches on this site and Google but didn't find the answer I want. Has anyone compared a 67 idler arm to a 68 side by side or using some accurate form of measurement? The 68 has the bolt through design but are the geometry and length same or different? Thanks for any input.
 
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JD Erisman said:
The topic of swapping a 67 to 68 K member, swapping 67 idler arms for a later version etc... has been beaten to death but I did numerous searches on this site and Google but didn't find the answer I want. Has anyone compared a 67 idler arm to a 68 side by side or using some accurate form of measurement? Geometry and length same or different? Thanks for any input.
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The 67 idler arm has a bolt that holds it to the K member similar to the 68 except that it is not captured like the 68 is by the K member it is merely bolted with a bolt with no other support. I would not try and use the wrong idler arm. So what are you working on?
 
I think the 68 is a safer design as it uses A double shear mount instead of a single bolt (stud). The older idler can bend and break the bolt (stud), the newer one can not bend at the bolt (stud) as its supported at both ends by a welded bracket.
 
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Thanks for the input, I edited my initial post to clarify my question. I have a '67 Barracuda.
 
The original arms do not have a bolt, rather they have STUDS both ends. People have modified 67 members to 68 bracket, but I don't know how you'd do that without a guinie pig

There are two or three problems with the 67 design

It is one year only
You cannot swap around linkage parts to the later 73 stuff
It is an inferior design and not as strong
They are more difficult to find and cost more for replacement
 
"The reason" you might want to swap to 68-72 or 73--later linkage is if you get a steering box that requires the larger pitman arm splines, you will have to use a 73/ later center link, so........

The pieces that MUST fit together 68 and later are
the center link, pitman arm, idler arm and of course steering box splines must fit the pitman arm. These are sorta grouped 68--72 and the other group, 73 and later. The studs for the tapered ends point up in one group and down in the other

If you keep a 67 idler arm, you are limited to the 68--72 group or actually 67--72 except for the idler

There are opinions by some---I don't know--that one group is better or worse for B/RB swaps, I "think" the later ones are supposed to be "the better" but that's memory
 
My thought process was: if the 67 and 68 idler arms are geometrically the same, why not use a 68 idler arm in place of the 67 by using the 67's mount and welding a tab above the 68 idler arm to allow the bolt through design of the 68 to be captured by a top and bottom mount. If the two idler arms are identical then the idea should work without cutting off a 67 single mount and welding on a 68 mount, just weld a top plate for the through bolt of the 68 to go through. I hope my idea makes sense.
 
JD Erisman said:
are the geometry and length same or different?
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Same.

JD Erisman said:
just weld a top plate for the through bolt of the 68 to go through.
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You'd need a bottom plate, not a top. And if you're going to be welding it up anyways, just weld on the correct bracket from a donor K frame. It needs a specific fore/aft angle to it or it'll throw your geometry off when you turn.
Make a jig from the donor K so it gets located precisely on your K.
 
Thanks for the input. I wish I could find a 68 mount, I live in a huge state with few people, I don't have salvage yards with any old Mopars to pick a k member from and I have looked for the last couple of years on and off for someone selling a 68 mount by itself. I cannot justify spending the money for an entire K member to be shipped to me. Tossing around ideas.
If the idler arms have the same geometry, size etc.. why wouldn't I be able to use a 68 arm in the same place of the 67, mounted the same but weld on a top mount for the 68's bolt to go through and secure the arm?
 
Yep that was me for both. Engine mounts and idler mount. Heres pix. To the OP, I converted a 67 slant sux K frame into a 68-72 V8 K frame.

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There is nothing wrong with the 67 ideler they have been working just fine for 54 years. That being said...

IMHO, if you are set on changing get a 68 up k frame. You can hang the engine from the fenders and unbolt the old one and bolt in the new one. Get the 68 idler and reuse all the rest of your suspension.

With a little help you could probably have it all switched out in a day.

As an FYI, 67 idlers can be had for about 60 to 70 bucks and there are some heavier duty ones for about 200 bucks.

Standard
1967 Dodge Dart New Idler Arm

Heaver duty
20218 - 1967 Mopar A-Body Replacement Idler Arm

Thee is also a retrofit kit if you have an older or original idler to change it to a stud and bearings on both ends
Firmfeel Mopar Suspension and Steering

But to answer your question, no dont know if the geometery is the same but it has to pivot about the same points in space.

My guess is you could machine a stud with a taper on one end and threads on the other. Bolt that to the K frame and slip on a 68 idler with a washer and a nut on the other side.
 
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The '67 bracket is in the middle of where the '68-up bracket would be. You cannot just add a top or a bottom flange and make it work. From my experience, there are actually more things to go wrong with the "better" (later arm).
 
If the 67 mount design was so superior then it would have been kept through the end run on these cars in 1976. It was used 1 year only on the second gen cars. The 68 idler mount goes all the way to 76. Better design. IMHO.
 
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I've read and read and read that the stud mounted is inferior.....and I agree it might be, but I ask "WHERE" is the proof? Has anyone ever SEEN a failure that was 100% WITHOUT A DOUBT the fault of the supposedly "inherently inferior" design? I've been doing this a long time and have not.
 
....also, IF you've seen a failure, "WHAT" was said person doing with said car when it happened? IF there is a weakness in the actual design, then I would suspect little old granny would have had one fail on the way to Sunday school. Not just the guys out road racin.
 
Well Rusty, go ask one of the engineers who designed these things. If they arent all dead already.

Heres my hypothesis on this. The reason for the change could have been one of 2 things or a combination of both. It could have been a cost cutting measure, or an upgrade in reliability, or possibly both. The single sided arm goes back to at least 1963. Perhaps there was a high failure rate back then, and an improved design single sided arm as a bolt on was made to correct the vehicles that were already on the road with that design, and the 68 up design was the permanent fix? Maybe the new replacement single sided arms have that improved design as well, so theres no issues.

Maybe the 68 up design idler was less expensive to manufacture? The 68 up idler arm mount is arguably a bit more involved from a manufacturing stand point than a flat tab with some gusseted sides and a tapered washer welded to it.

Maybe the mount cost more to make, and the arm was less, but in the end maybe they saved .25 cents per car. Doesnt seem like a whole lot, But if you add that up to let's say roughly 250,000 A bodies made in just 68, that's $62,500 saved in manufacturing from just 1 part redesign.

Being that it is an arm rotating side to side pushing or pulling the mass of a wheel, tire and brake, I can argue the fact that the 68 up is a stronger design because its captured at the top and bottom spreading the load evenly across the pivot point. This is still a moot point however because these cars were all designed with a 10 year life span, and either design has shown they last longer than 10 years before wearing out.

Being I have a 67 notchback and a 69 notchback I have seen changes in both cars where the factory cheapened up the manufacturing of the 69 compared to the 67. It's almost as if as soon as the 67s went on sale, the bean counters descended on the car to figure out ways to cut the manufacturing costs.

The fact of the matter is we can only guess as to why the factory did what they did 53 years ago. Was it a design improvement, or a way to make the cars cheaper, or both? I will stick with it being a design improvement because if it was good enough, they never would have changed it.

Just my .02
Matt
 
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Some times it is just cheaper. I have never seen a problem with an early idler arm mount. Never would I modify a 67 K frame just to swap to the later idler arm. I have a 67 Barracuda with 400,000 miles on it. Lost it on ice, went through a ditch, through a barbed wire fence, and back again. Idler mount is still fine. I have replaced a 76 K frame with a 67 because the 76 was messed up. Worry about enjoying your car, not every hypothetical problem.
 
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My question wasn't whether it can be argued. I already know that answer. We're here doing it. My question was has it been PROVEN?

I'm not arguing the single supported idler arm might not be weaker. I'm wanting definitive, recorded, PROOF. So far, I've seen none. All I see is a "different" design from early to late, "SO FAR".
 
The "proof" as "somebody says" is "circle back on that." The PROBLEM is the damn things are way more expensive and difficult to get. That alone makes them "weaker" so to say

I see no way, by the way, that a nice big through shaft (bolt) to a substantial bracket on both ends is "inferior."
 
67Dart273 said:
The "proof" as "somebody says" is "circle back on that." The PROBLEM is the damn things are way more expensive and difficult to get. That alone makes them "weaker" so to say

I see no way, by the way, that a nice big through shaft (bolt) to a substantial bracket on both ends is "inferior."
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Only if rusty says it is lol.
 
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