Don’t understand how pitman and idler arm work at spec torque settings?

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LovetheA's said:
So I removed the idler arm and looked at the hole where it bolts to the k frame. The hole looks pristine and perfectly round. I’m thinking that with the 67 k frame maybe the idler arm should be a little tighter than on the 68 and up k frame. I also held onto my old idler arm and compared it to the new one from PST. Actually the bolt through swivel point on the new older arm to the left in photo is smaller by .030 thousands as compared to the older idler arm to the right. Therefore I can’t see it not working just as well as the older one? I guess I can put in the new one tighten until I think it is 40 ft lbs hook up steering and see with my 16:1 manual box if I can turn the wheels. Car is up on jack stands. Live and learn!
Carl

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couple of things I noticed: maybe it's just the perspective of the photo, but the idler on the right appears way more stout than the new one on the left.
why did you have to dent the headers so much? It may be a little late in the game, but maybe you could have shimmed the motor mount biscuits to reduce interference with the tubes.
if the male taper is too small for the female taper, when you tighten the stud nut, you could be pulling the taper thru the hole so far that it is binding the ball socket shoulder against the x-member bracket.
 
Just had a thought... You said you have a 16:1 stearing gear.

Is the gear 16:1 OR do you have a quick ratio pitman arm?

If you have a quick ratio pitman arm and a standard idler arm you might be putting the geometry into a bind.
 
30 thou taper length is not an issue. Its still gonna bottom into the tapered socket and give you enough threads to torque it down. As you can see the felt washers are nothing but grease seals. Bummer on those headers.
 
pishta said:
30 thou taper length is not an issue. Its still gonna bottom into the tapered socket and give you enough threads to torque it down. As you can see the felt washers are nothing but grease seals. Bummer on those headers.
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I'm sorry, I thought he meant 0.030" difference in taper diameter.
 
Yes the difference in taper diameter is .030 thousands. Not the length of the tapered threads. I don’t have a quick ratio pitman arm. The box has been upgraded to 16:1 ratio. I believe the pitman arm is a standard one. Yes the idler arm is unique to the 67 dart. The older one is much more stout. I think that is indicative of the quality of modern replacement parts being **** quality vs older replacements. It’s very unfortunate. I’ll try the new idler arm and if there is a problem I can always put the old one back in. The new idler arm tightens down after being torqued so that the foam gasket is just slightly compressed. That’s where the idler arm’s travel into the k frame stops. I’m not able to move it by hand but I think it’s because it is brand new and I’ll have to see what the movement feels like with the steering back in? If it doesn’t move or binds with the steering in I thinking I could do two things. One loosen the castle nut a little and see if it makes a difference with the steering and then make sure to lock it in place with the cotter pin or two just put the old idler arm in. Quick question. Is there a trick to lining up the castle nut with the hole in the tapered shaft? It is impossible to see it from below based on where it’s located.
 
Yes now that I think about it I should of shimmed the motor mounts to make more clearance for the suspension. I just ran into many places were I had to use the BFH to make the TTI’s fit. I didn’t want to mess with it much more as it was a real PITA to get them to fit the car being a 4 speed and having much bigger torsion bars. So much for direct drop in and go.
 
LovetheA's said:
Yes the difference in taper diameter is .030 thousands. Not the length of the tapered threads. I don’t have a quick ratio pitman arm. The box has been upgraded to 16:1 ratio. I believe the pitman arm is a standard one. Yes the idler arm is unique to the 67 dart. The older one is much more stout. I think that is indicative of the quality of modern replacement parts being **** quality vs older replacements. It’s very unfortunate. I’ll try the new idler arm and if there is a problem I can always put the old one back in. The new idler arm tightens down after being torqued so that the foam gasket is just slightly compressed. That’s where the idler arm’s travel into the k frame stops. I’m not able to move it by hand but I think it’s because it is brand new and I’ll have to see what the movement feels like with the steering back in? If it doesn’t move or binds with the steering in I thinking I could do two things. One loosen the castle nut a little and see if it makes a difference with the steering and then make sure to lock it in place with the cotter pin or two just put the old idler arm in. Quick question. Is there a trick to lining up the castle nut with the hole in the tapered shaft? It is impossible to see it from below based on where it’s located.
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you can insert a punch or something into the cotter pin hole and spin the stud around to whatever direction facilitates insertion & removal of the cotter pin, before you push it into the taper hole.
 
Make a mark on the body of the idler in line with where the hole is. You don't want to loosen the nut. The post might start to spin. If the post is tight and the idler housing isn't rubbing on anything, and you can't move it by hand, there's something wrong with it internally.
 
LovetheA's said:
The new idler arm tightens down after being torqued so that the foam gasket is just slightly compressed. .................. I’m not able to move it by hand Is there a trick to lining up the castle nut with the hole in the tapered shaft? It is impossible to see it from below based on where it’s located.
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foam gasket..........This indicates the stud is not too deep and is not binding the main part of the arm

not able to move..........how strong are you? it might take some force on a new idler, let's say 20-40 lbs pull like you were pulling on a wrench and that would be extreme, but you SHOULD be able to move it. I'm still leaning towards a DEFECTIVE part

castle nut.......I just "look" at the hole before screwing it together and sort of memorize it, then approach nut tightness a little at a time . If you cannot see it you need something stiff, piece of wire, paper clip, to probe it. Don't you have an inspection mirror? "The old man's friend LOL"
 
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I don’t think if it’s my lack of strength. I’m a pretty stocky muscular guy. 5’ 10” not fat about 215 lbs. Thank you everyone for again being a valuable resource and helping me with my project.
Carl
 
I haven’t tried to really push or yank on it real hard though. Just tried moving the cross link. I’ll check it out closer tonight.
 
I would suggest getting the full suspension torqued and greased and see how the steering linkage moves in unison by cycling it left and right. If there is a problem with the idler arm at that point we will address it for you, but I do not see you having an issue.

Thanks
James From
PST
 
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