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trunnion question

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tomj View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/19/2021 at 12:20am
I have 64 Ambassador upper arms and trunnions out on my workbench, part of an active project. I will re-photo them tomorrow. What I don't have is the spacer part (maybe you can measure yours for me, though I can infer it).

I did assemble one a week ago (I'm making a ball joint suspension for the early American) so that I could verify dimensions, and it did come out to 8.25", which is why I remembered that off the top of my head (had to look it up one week ago).

1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Jan/19/2021 at 7:22am
Well, the whole assembly isn't exactly "precise". You might have to turn one arm more than the other. On the big car suspension you can run the caps into the arm then rotate the entire arm onto the trunnion stud. Work one side at a time. Check the distance once you get both on in what appears to be the "right" position. You may not get the exact same measurement as Tom did, but should be close.

Rather than rely on Loc-Tite to hold the cap in I suggest a small tack weld near the outer end of the arm. Position the weld so it can be reached with a grinder or chisel later. in case it needs to come off. Just a quick, small tack is all you need. That's enough to keep it from turning. I have lost a trunnion cap (lower, 63 American) on a trip... not fun! On the big car you can put the cap in the arm, take it to be tack welded, then go back and assemble. The 58-63 American uses a mounting bar on the inside end of the lower arms, so you can't assemble one arm at a time like the big cars. Upper is totally different on the Americans.

That said, the upper arms don't receive the shock or as much movement as the lowers, so the red Loc-Tite should be enough...
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote sjaakslinger Quote  Post ReplyReply Direct Link To This Post Posted: Jan/19/2021 at 1:00pm
Worked on the upper arm again today. Already fixated one cap with loctite a week ago, seems to hold up well enough. Still not happy though. With the entire upper arm correctly assembled and the trunnion moving freely, the bushing just about fits between the arms. So far so good. Trunnion still moving freely. But as soon as I tighten the spacer, it still somehow puts force on the trunnion and the trunnion is quite hard to rotate a bit. Tried several options by rotating the spacer a bit, etc.

Might work when installed, but I find the the trunnion quite difficult to move by hand (rocking it a bit back and forth as on the car). Other option I'm considering is putting a very, very thin spacer or round gasket next to the spacer. Might not be 'the correct way' to solve this, but I'm running out of ideas.


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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/19/2021 at 3:23pm
OK, I added a new assembly sequence, photos and much more detail, to that page:


Given that I'm using parts off my shelf, and not for a real car, the trunnion I used was dirty. It will NOT assemble right if the parts are dirty. Suspension parts are about the grubbiest things on a car, but the moving parts must be spotless. After 50 years, they are unlikely to be. I apologize if you know this and your parts are all clean, but I can't see them, hence this paragraph.

Loctite is not a good idea, and unnecessary. Blue, I hope, and not red, but may be fine.

If it's binding when you torque the bolt for the spacer/stiffener, something's wrong.

Go over the new photos in the page above. Each step has to complete with satisfaction before proceeding. I have the parts out now so if you have specific questions I can mock them up and measure, etc.

Suspension parts look heavy crude and ugly, but they are precision parts. A lot of the design changes, eg. ball joints, strut rods, etc, is to make them a lot less labor-intensive and relatively in-sensitive to dimensional changes (eg curb bonks). These old trunnion suspensions are very sensitive to bent parts. I'm having a heck of a time finding small-car lower control arm halfs that are even usable.

You may have to take it all apart and start over.

It would be very helpful if you could post photos.



1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

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tomj View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/19/2021 at 3:36pm
I figured out years ago that all of these things need to be scrubbed very clean, once. Maybe every 20 years, whatever. Crud rust and grease hides cracks, gouges and ruin from previous bad repairs, grit that looks "like nothing" is actually ten thousandths of an inch thick and preventing proper assembly.

I do this the first time I tear them down, later work, if I have the car that long, is then easy, and wipe with a rag/wire bush is enough. But 50 years of use and abuse hides a lot of ugliness. These haven't been "used cars" since 1975. They're antiques.

1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Jan/19/2021 at 4:03pm
Your upper arms may be bent slightly at the ends. It shouldn't hurt if the trunnion is a bit tight, but it shouldn't be so tight that the cap turns in the arm. A thin shim in the spacer won't hurt. Might be easier than trying to straighten the arms. As long as that cap stays on nothing's going to come apart. As long as the spacer is tight it will support the arms and hold them together. While ideally a shim shouldn't be necessary, as Tom says, it IS a 50 year old antique and sometimes things are worn more than the factory ever expected.
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/19/2021 at 10:06pm
Unless the arms are bent, or the nuts are not squarely bottomed in the arms, it will come out to 8.25" plus/minus 1/32" or so, with the additional bit of play due to clearance/looseness in the threads themselves.The trunnion "arms" are 5/8-11 thread, it's a precision forging, as are the caps, so threaded on it is very repeatable.

If the trunnion end of the arms is bent, they won't be parallel, and the gap won't be parallel. However it is extremely unlikely that the upper arms are bent, as they're under surprisingly low side load. 

The 61? to 67 big car suspension is a fine thing. Weird in it's way, but very tolerant of out-of-spec parts. Odd to adjust, some hard to find wear parts, but very reliable.

I disagree on welding caps, unless you are forced to use damaged parts (soon to the the case for Americans). We haven't heard enough hard detail from the OP here to really have a handle on what the story is. No photos. They need to be very clean. I know lots of people will disagree with me, but everything goes easy and "by the book" (where it exists...) and I tell you, I'm pounding the crap out of ancient American parts, used lower arms, caps "merely" tightened. 

AMC didn't use loctite, nor weld, and those front suspensions didn't fall apart until a decade or more of poor or no maintenance.

1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

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Post Options Post Options   Thanks (0) Thanks(0)   Quote sjaakslinger Quote  Post ReplyReply Direct Link To This Post Posted: Jan/20/2021 at 6:35am
Thanks guys for all the info and pictures. I consider myself a perfectionist when it comes to stuff like this, but I gotta be practical as well. I don't have easy access to parts since I'm in The Netherlands, so it's difficult to just give it a try with some other arms or trunnion maybe. Gotta make it work somehow.

Sorry about the missing pictures, thought it wouldn't enlighten the issue much more. The arms were all disassembled because we're doing the entire front suspension. Replaced all ball joints, bushings, idler arm and pitman arm. New bearings in the trunnion and new thrust bearing. All the metal got blasted and repainted. So upper arms got intermixed. Passenger side is mounted, so maybe the upper arms on that side are partially from the other side. Maybe that contributes to the issue. 

I'm not doing a full restoration (although it almost seems like it since more issues show upConfused), so 'acceptable' is what I'd settle for. I'll check the arms and caps again next time, make some pics, try with a thin additional spacer, see how that works out and go on from there...

Again, thanks for all the help.

Dennis
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Post Options Post Options   Thanks (0) Thanks(0)   Quote farna Quote  Post ReplyReply Direct Link To This Post Posted: Jan/20/2021 at 6:39am
Just a small tack weld is all I recommend, just for peace of mind. Red loc-tite should work also. Good condition replacement arms, checked and maybe refurbished, are the best solution, of course, as you're pointing out.

Now, as to why.... the pressed in hole has some tension on the inner lip when new. This expands some when the trunnion cap is screwed in and holds it. As you noted, those aren't really "threads" on the outer diameter.  When you screw it out it doesn't "shrink". Old parts for one thing. It could be worn if the cap started to turn some as well. I've taken a hammer and carefully tapped around the inner edges of the hole to slightly shrink it with good results when the cap screwed too easily back in the arm. Try a cap in the arm without the trunnion. If it screws in easily (especially if by hand!) the hole isn't tight enough. Shrink, just that one small tack weld, or loc-tite should hold it -- what you do depends on how worn and what you have available.

I'm not so sure the blue loc-tite will hold under stress, though it shouldn't have much stress as long as it's well greased and not binding in some way. But you can take it apart if you use the red, just takes some more effort.

On one car I welded the cap nut into the arm. The arms were badly worn -- one side of the pressed in part was gone -- and I couldn't locate another set on short notice. So I put the caps in the correct position (lower arm assembly off car and assembled) and welded them in. Lost the o-ring "seals" to heat, not a big issue. I later located another set of arms and trunnions (actually a whole parts car!) so I'd have them on hand should something wear, but that never occurred after several years of driving. To replace the rubber inner bushings one arm would have to be cut though, and if I did that I would replace both with good arms and new trunnions, of course. That was the plan, but sold the car before that happened. I did note what I'd done to the buyer, of course.
Frank Swygert
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Post Options Post Options   Thanks (0) Thanks(0)   Quote First_Gear Quote  Post ReplyReply Direct Link To This Post Posted: Jan/20/2021 at 10:04pm
Ahh.. You say you mixed parts with the other side? This is likely why its tight. These things wear together. Mine was actually difficult to turn until I put the right cap on the right side etc. I have a 66 classic so its the same suspension. It will probably wear in and be ok.

Make sure you measure the correct distance with installing the lower control arm bushing! It is in the TSM. 

Also there are two separate front springs. One is the left spring and one is the right spring. The part number is stamped on the last coil. One of them is slightly stiffer than the other to make up for the weight of the driver steering column and exhaust manifold.

If you don't have a parts book I can look up which part number is the left one and which one is the right. I think its out in the garage right now otherwise I would post it. I found this out when I had mixed up the rear springs with the front springs and was looking at the P/N. The number is hard to read. I find breathing on it so its covered in condensation seems to make it much more legible.
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