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1961 American front suspension rebuild

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tomj View Drop Down
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    Posted: Jan/06/2018 at 3:19pm
OK, i'm doin' it. car's apart for the winter, new electronics again, a roll hoop, other minor stuff, and front end rebuild. it's been getting sloppy since it was last done in 2010 i think.

got it apart and the bushings were worn, but not bad. i probably wouldn't have taken it apart for that alone. tire wear was perfect, no cupping, but it started shuddering over rough stuff, and jacked up and wheel removed, the upper trunnions were the problem, as always.

when i first attacked this in 2010 i had to grind the trunnion pivot bolt out thread by thread, it was as bad as they can get, completely frozen, upper arm holes ovalled etc. i fixed the arms and instead of buying a hard bolt that is the source of the trouble (it resists lubrication, by design) i made a new system. that's worked fine except as below; its described on my website but basicaly i bought a chrome moly threaded rod, flatted a portion, drilled a crosswise hole, and drilled the trunnion casting for a Zerk fitting.

that absolutely solved the lubrication problem.free-flowing grease out both ends of the casting. the problem (and feature...) is that since it's not hard, it wears relatively fast. but because a high quality 36" chrome moly rod from MSCDirect costs less than one NOS replacement bolt, and provides metal for a half dozen bolts, its a fine tradeoff.

interestingly it wore very evenly. my shuddering was the rod wear let the assembly rattle a bit. absolutely not a safety issue, it would be many more decades of wear to do that.  but the upper arm threaded holes got loose somehow, and ovalled again, slightly.

the more i learn about this suspension the less i like it. i'm not blanket-opposed to trunnions, the big-car trunnions are great, but this design is crap. it is bad by design. this will be the last time i rebuild it. i no longer think it was even "ok for 1960". the upper arm outer pivot business is just crap. its stupid to put forces like that on vertical section .125" stamped arms.

winter of 2018 i will do what i considered earlier, build one from scratch using "race car" parts; a "ball joint plate" and Ford type upper pivot bar, rubber-bushed upper-inners. weld or bolt a spring perch to the ball joint plate (one issue there, tbd). lower arm is easy, chebby balljoint and rubberbushed adjustable arms on a Ford type pivot bar. need to rig a plate and clevis replacement for the K member, but that's easy.

i have a simple fix for the upper arm ovalling problem; since i'm not running the stupid bolt, i'm going to assemble the upper arm completely, thread a nut onto each end of the threaded rod to put it in position, and weld a nut to the outside of each arm end. then there will be .5" of metal to support the rod and a jam nut each end. done and done.

pics to follow...


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 (1) Thanks(1)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/06/2018 at 3:46pm
i got the whole thing stripped down to metal, scrubbed clean, inspected for wear. some gouging on the lower arm outer end where i'd overtightened the trunnion caps, nothing fatal. upper arms, as mentioned, the trunnion casting pivot is AFU.

i had previously worked out how to assemble new bushings from these nice soft black poly bushings i got from RideTech.com, and i'll later (soon) document that on my website. they went together as expected, the order of events is a bit tricky because the ID is too small, sine the AMC parts are peculiarly 11/16" diameter for which no one makes anything. i've got bushings with 5/8" holes, so they're stretched more than i like. later on this.

but i assembled two so that i could put together one upper arm and trunnion to see how that wear is.








and view from the "outside":







yeah that's what that mess looks like, even with the AMC bolt. the TSM has very little to say about this part, except to warn about the bolt going back into the same arm as it came out; the arms are otherwise identical, so i think it cut the stamped hole when first assembled.

i agree that it looks like there are far too many threads showing between casting and arm; the cross-bolt is in place here. i could find no error last time, and it ran this way for nearly a decade. there's obviously a seal that goes in there, here it's dry and no seal. (i use two fat O-rings for seals; a whole bag of NEW RUBBER parts costs less than old, dead NOS or 20+ year old aftermarket crap).

(the hole behind that Zerk is made to align with a cross-hole in the rod that feeds two parallel flats on the rod. that worked, but reduced rod metal too much. this time i'll simply reduce the threads down to the root, abot 1/4" wide, right where the zerk is, similar to the early 232 head bolt oiling fix.)

the "bolt"/rod is supposed to be fixed relative to the arms; the casting pivots on the long section of thread. that's the theory. in practice, nearly all of them end up with the rod/bolt rotating in the arm. even just a tiny bit of motion allows the bolt to hammer the then arm section. it's just stupid on it's face. my proposed fix of welding a nut to the outside of each arm (pic below) will end that. then the jam nut can be torqued hard enough against the arm to actually retain it.

however after 50 years the threaded hole in the casting is worn, now. the new length of rod shown here slightly rattles in the hole, and there's nothing to be done about it except drilling out out and finding some exotic 11/16-NC or NF hardware, or radically altering it to accept a bronze bush and some real pivot. but there's not a lot of casting there to bore out for a bronze or oilite. what a piece of crap.

[EDIT: turns out that i have a couple more sets of upper trunnion castings in the iron pile, and the threaded hole is a lot tighter. my current set either wore from my use, or from when i had to chatter/grind out the old frozen bolt. in any case i'm in good shape here.]














Edited by tomj - Jan/06/2018 at 4:09pm
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 tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/06/2018 at 3:53pm
here's a couple pics of the new poly bushings in place. they're fairly soft, not much harder than rubber. i like it a lot. cheap too, $2 each (need 16). i had to make a jig to fly-cut them shorter.















i'm not satisfied with them, yet anyway. the arm pivots over the *outside* diameter of the bushings, because they are tight on the inner. i'm not sure of it matters, or if it does, how much. the issue will be friction and wear and heating of the poly. will it get hot enough to deteriorate? it needs to last a year is all, since i'm definitely ditching this stuff.

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 tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/06/2018 at 3:59pm
just for grins -- here's a 1963 CLASSIC upper trunnion and arms on a 1961 AMERICAN steering knuckle. perfect fit! the arms are even the exact same length!

of course this is a stupid idea, jumping from the frying pan into the fire, unless you happen to have all these things laying around, and i do.

a lovely thing also is that the Classic spring had that screws onto the top of the trunnion is waaay too tall for the American -- but i am running an air spring, which is very short, 6" or so, and it almost works as-is. but it's no big deal to chop the spring hat down and weld it.






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 tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/06/2018 at 4:14pm
last for now, here's the wear on the 2010 pivot threaded rod:



that's about .02" of worn off threads. this is at least partially due to a flaw in my previous rod, where i flatted it to create a grease passage. it worked, but i removed too much metal, which increased wear. this time i'll make a narrow channel.



above is the back side; it was inserted so that the cross-hole aligned with the zerk, and this flat was vertical, and on the inside.




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/08/2018 at 10:16am
Yeah, use a cut-off wheel to make a channel just the depth of the threads. Also, that's a standard 5/8" thread, IIRC. When I made mine I used a hardened stud from and industrial supply company, as used in refineries and such. Just get one close to the same length.

I also repaired the arms as you are going to do -- welded nuts to the outside. I used thin jam nuts welded on and as the jam nuts. Standard thickness nuts are likely too wide because of where the wheel fits the small Americans. I don't recall if it was too wide or I just used the thinner jam nuts because it made a neater looking package. I welded the nuts with the front suspension fully assembled. I then took the trunnion pin out and put in the fat o-rings (which is really all the factory seal was). Well, I took it apart and put the seals in after the welding heat melted the one's I first put in... oops!! My pin was seized but I managed to get it out... with great difficulty! Old dino based grease along with heat/pressure/time appears to make a good epoxy/welding compound. My arms were egg shaped on the ends, but the wear was all to the rear (toward car body), the original lip for the threaded pin was still on the outer end, gone on the inside. So I assembled and pulled the pin to the outside, then tack welded the nut on each side so they would be in the factory position... or as near as I could get them so.

The only issue with using the Classic type trunnion is that the horizontal pivot on the Classic runs through the vertical pivot center line. The 58-63 American trunnion has the horizontal pin to the inside of the horizontal center line. The vertical pin is therefore about an inch "in" toward the body on the 58-63 American. That will affect camber. I don't know if the steering knuckle takes that into account or not -- you might be able to use the 63-66 Classic steering knuckle as well, assuming it does. You could also use a lot longer bolt and spacers on the lower control arm -- it doesn't have much stress on it. I'd make some solid spacers and not try to use that thick a stack of alignment spacers though.

The spring seat is offset to the inside on the American also. The spring seat rides above the tire on the Classic, beside the tire on the American.  As you stated, using your air springs there probably won't be an issue. Wouldn't be hard to cut the threaded tube on the Classic seat down and weld an offset spring seat on top either... or use custom made shorter springs. The stock 58-63 American springs are rather tall....
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/08/2018 at 10:58pm
Originally posted by farna farna wrote:

I also repaired the arms as you are going to do -- welded nuts to the outside. I used thin jam nuts welded on and as the jam nuts. Standard thickness nuts are likely too wide because of where the wheel fits the small Americans. I don't recall if it was too wide or I just used the thinner jam nuts because it made a neater looking package. I welded the nuts with the front suspension fully assembled. I then took the trunnion pin out and put in the fat o-rings (which is really all the factory seal was). Well, I took it apart and put the seals in after the welding heat melted the one's I first put in... oops!! My pin was seized but I managed to get it out... with great difficulty! Old dino based grease along with heat/pressure/time appears to make a good epoxy/welding compound. My arms were egg shaped on the ends, but the wear was all to the rear (toward car body), the original lip for the threaded pin was still on the outer end, gone on the inside. So I assembled and pulled the pin to the outside, then tack welded the nut on each side so they would be in the factory position... or as near as I could get them so.

i'm using full-sized nuts. if you were to keep the original bolt or use a similar solution you'd need to use a thin nut (jam nut). i used threaded rod, and double-nutted each end. it wasn't attractive but it was reliable. the overall length is only 7" or so, plenty of room. the next one will look similar but the inner nits will be welded to the arms.

mine are ovalled a bit, but the correct original position is easily discernable so i'll have an easier time of it.


Quote The only issue with using the Classic type trunnion is that the horizontal pivot on the Classic runs through the vertical pivot center line. The 58-63 American trunnion has the horizontal pin to the inside of the horizontal center line. The vertical pin is therefore about an inch "in" toward the body on the 58-63 American. That will affect camber.

right, that's an issue. i'm unlikely to persue this, but it's interesting! the 01 upper trunnion does have that offset. it would produce a huge amount of positive camber. last thing we need! lol


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/09/2018 at 6:31am
If full sized nuts don't cause clearance issues no harm in using them, but the thinner jam nuts would look better... but who's removing the tire to look?

I had thought that the 50-54 Nash Rambler used the same type of upper trunnion as the Classic, but I just checked a 50 TSM -- that's wrong! It didn't have the big casting (that appeared in 55), but it had a "crossed tube" type upper trunnion where the horizontal "tube" is to the outside of the vertical -- similar to the cast upper trunnion. The spring seat is also offset -- it's a stamping with a big plug type nut that screws into the top of the vertical pivot "tube". It would be easy to make a bronze bushing piece in that manner -- use some good steel tubing with oilite bushings, and a spring seat somewhat like the Classic. AMC just went from the 2-3 piece trunnion/spring seat to the single cast piece to reduce assembly time/cost by a few minutes. Probably not much cost savings (if any) in the part itself.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/09/2018 at 10:32pm
that's pretty interesting. none of this stuff is worth the effort though, though i have more respect for the incremental fixes AMC did for the "big car" in 62-up, this thing is junk. it's just too weak for modern use, parts are impossible to get right. this will probably be the last time i do one of these. 

i'm going to buy one or maybe a pair of "ball joint plates" and see if i can't mock one up with the parts i have now, just to visualize what a real suspension would be be.

the biggest questions are around the spindle, obviously enough. camber and ackerman stuff. it will almost certainly be some chevy spindle simply because they're so available and cheap. brakes and hub and bolt pattern and wheel bears are not a problem.

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 (1) Thanks(1)   Quote tomj Quote  Post ReplyReply Direct Link To This Post Posted: Jan/09/2018 at 11:38pm
frank, here's one for ya.,. lol

OK if you put the big car upper trunnion on the little car, the outer pivot of the upper arms, moves inboard an inch (guess, too lazy to measure), which set uu 5.4 degrees of POSITIVE camber, lol. but! if you compensate by shortening the upper arms by that same inch -- technically not a big deal -- you go back to 0 camber straightahead, and substantially improve the car's roll center a lot. 

(EDIT: wrong, shortening the arms *is* a big deal -- they're legs of a triangle. too bad! )


* stock, it shifts 14 inches to the wrong side, for each degree of chassis roll.

* hacked as above, it shifts 9" for each degree roll.

* if you also drop the upper arm's inner pivot bar 2 inches, which would be difficult but not impossible -- and i hadnt considered that shortening the arms would allow spacing the pivot bar further from the chassis, making this easier -- then 

* 2.6" roll center shift for 1 degree body roll. 

THATS GREAT GEOMETRY! at least in a 2D look.

here's the calculator at VSUSP.NET that i used. i measured all that stuff on the car, now that it's apart i'll check the measurements.

http://vsusp.com/?tool=2d#0.8%26project_name%3Arambler%20roadster%2C%20upper%20mount%20lowered%202%22%26trim%7Bbody_roll_angle%3A100%7Cfront.left_bump%3A0%7Crear.left_bump%3A0%7Cfront.right_bump%3A0%7Crear.right_bump%3A0%7D%26front%7Bframe.susp_type%3A0%7Cframe.bottom_y%3A16510%7Cframe.center_to_upper_mount_x%3A32764%7Cframe.bottom_to_upper_mount_y%3A29208%7Cframe.center_to_lower_mount_x%3A29208%7Cframe.bottom_to_lower_mount_y%3A5334%7Ccontrol_arms.upper_length%3A22542%7Ccontrol_arms.lower_length%3A30479%7Cknuckles.hub_to_upper_x%3A15875%7Cknuckles.hub_to_lower_x%3A11430%7Cknuckles.hub_to_lower_y%3A8572%7Cknuckles.hub_to_upper_y%3A18414%7Cknuckles.hub_to_strut_axis%3A14000%7Cknuckles.strut_incl%3A8000%7Csteering.active%3A1%7Csteering.hub_to_outer_tie_rod_x%3A12700%7Csteering.hub_to_outer_tie_rod_y%3A5080%7Cwheels.offset%3A2540%7Cwheels.diameter%3A1600%7Cwheels.diameter_expl%3A35000%7Ctires.size_convention%3A0%7Ctires.section_width%3A20500%7Ctires.aspect_ratio%3A5000%7Ctires.diameter_expl%3A50000%7Ctires.width_expl%3A7620%7Ctires.compression%3A0%7D%26rear%7Bframe.susp_type%3A0%7Cframe.bottom_y%3A15238%7Cframe.center_to_upper_mount_x%3A32764%7Cframe.bottom_to_upper_mount_y%3A33020%7Cframe.center_to_lower_mount_x%3A29208%7Cframe.bottom_to_lower_mount_y%3A5334%7Ccontrol_arms.upper_length%3A25082%7Ccontrol_arms.lower_length%3A30479%7Cknuckles.hub_to_upper_x%3A13969%7Cknuckles.hub_to_lower_x%3A12700%7Cknuckles.hub_to_lower_y%3A8255%7Cknuckles.hub_to_upper_y%3A18732%7Cknuckles.hub_to_strut_axis%3A14000%7Cknuckles.strut_incl%3A8000%7Csteering.active%3A0%7Csteering.hub_to_outer_tie_rod_x%3A-5715%7Csteering.hub_to_outer_tie_rod_y%3A15238%7Cwheels.offset%3A3809%7Cwheels.diameter%3A1600%7Cwheels.diameter_expl%3A35000%7Ctires.size_convention%3A0%7Ctires.section_width%3A20500%7Ctires.aspect_ratio%3A5000%7Ctires.diameter_expl%3A50000%7Ctires.width_expl%3A7620%7Ctires.compression%3A0%7D%26pref%7Bdiag1.px_per_mm%3A200%7Cdiag1.front_or_rear%3Afront%7Ctab.active%3A2%7Cunits%3A0%7Cshow.f%3A1%7Cshow.ca%3A1%7Cshow.k%3A1%7Cshow.st%3A1%7Cshow.stl%3A1%7Cshow.w%3A1%7Cshow.t%3A1%7Cshow.rc%3A1%7Cshow.rcl%3A1%7Cshow.ic%3A1%7Cshow.icl%3A1%7Cshow.fvsa%3A0%7Cshow.tl%3A0%7Cshow.kpil%3A0%7Credraw_during_drag%3A1%7Cchart.x_axis_center%3A0%7Cchart.x_axis_window%3A10%7Cchart.x_axis_num_steps%3A21%7Cchart.x_axis_field%3Atrim.body_roll_angle%7Cchart.y_axis_fields%3A%5BFR%5D.general.roll_center.y%7D



Edited by tomj - Jan/10/2018 at 12:04am
1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5
http://www.ramblerLore.com

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