Minneapolis Moline Knoedler Seat Frame

[RCW]

My 1953 Minneapolis Moline ZAU came with a "fancy" suspension seat frame.

It looked like this. Unfortunately, I can no longer find parts diagrams from AGCO. This is the best I can do:

It broke in the early '70's. Now I have this:

But I have the frame. It lacks the central coil spring and shock. It also lacks what I think is a “U”-type shaped bracket to secure the spring/shock assembly together, while providing “posts” that go in the upper support notches.

I’m looking for suggestions on how to size an order the coil spring/shock assembly.

I assume I would get the coil spring, and find a shock to fit, then make them work.

I think I can fabricate a top bracket with tabs.

I just don’t know how to search for the parts I need.

We have bunches of junkyards around, but they’re U-Pull It. I don’t want to pull coil springs from cars just to check dimensions.

Any help is greatly appreciated!

 

[RCW]

Follow up - forgot to add:

Best I can figure is coil spring is/was about 3" OD top and bottom, and about 14" tall.

I did see some seat springs were 100 lbs/inch. Assume I need something like that versus 650+lbs/inch for suspension purposes.....

These parts are almost impossible to find used or NOS. Thank goodness I have the frame... (I saw just one of the brackets for $40 on eBay).

I bought a very good used governor from a nice fellow in Manitoba a few years ago, and he had no seat parts....

I am a member on a MM forum also. If I were to pose this question there, I might hear back in a couple weeks....some gifted guys, but I know there's some guys here that know how improvise.

 

[bird dogger]

RCW, for a very basic starting point to get a close estimate of shock absorber & spring lengths, you could try this:
Since you have the original frame work and that parts diagram to work with.....use a pair of dividers (think drafting tool) and measure the actual center to center distance of the two pivot points on the main bracket. Print out that parts diagram and set the dividers to the same on that diagram. Use that setting on the dividers to get a close estimate of the length of the shock and spring in that same diagram. IE: is the shock 1.5 times longer, 2x, 1.25x, etc. Multiply that by the actual measured distance should give you a fairly accurate place to start looking at for the lengths. The coil stiffness would be another issue.

At least it can give an estimate and just might not be too far off at that. It might just confirm your 14 inch estimate. Good luck!

 

[D2Cat]

I have a friend with a couple of MM. I can check with him to see what his seats are like. I do know one of his tractors has a seat that rotates sideways while using the tractor.

Seems like MM were more popular up north around Minn/Dakotas.

What year and model is your tractor? It looks like the bracket on the seat and the bracket coming from the seat to the tractor (with the spring) are not original. They are different shapes then the picture you show.

 

[RCW]

'Cat - '53 MM ZA.

Thanks for checking.

MM had several different swivel-type seats on their row crops. Different shapes, etc. Couple used similar suspension frames w/ coil/shock in different arrangements.

The seat drawing is from a MM book. Was a Marketing piece from the '50's, so not very technical. At least it showed me how it went together, just a little.

Been looking for real photos. No luck so far.

The seat suspension frame is original. The swivel-arm bolted to the tractor is original.

The seat pan/L-bracket I have on it now were a cob-job 40+ years ago.

The bracket bolted to the pan is a duplicate to the top pan-mount on the seat frame I have. Was from another MM Z we had in a boneyard. That was the $40 part I found on eBay, and I have 2....

 

[BAP]

RCW, have you tried going on to Yesterday’s Tractor Forum? They have a MM section that looks like it is fairly active.

YT Forums Have Moved

 

[RCW]

RCW, have you tried going on to Yesterday’s Tractor Forum? They have a MM section that looks like it is fairly active.

YT Forums Have Moved

BAP - - yes, I'm a member there. I will likely look for some help there too.

They were great help with the governor issue while back.

Found a couple pictures.... first is a '52 ZA, next is a U, but identical system used.

 

[Ping]

RCW, short of finding an OEM setup, would a motocross rear coil over be in the ballpark size wise?

 

[bird dogger]

D2Cat is right. We grew in the Red River Valley MN/ND and lots of MM's all over the place. If you google
"ND tractor salvage yards" you'll get a list of possible places to find parts. "PETE'S" is one of the bigger ones close by in my area. An email or phone call may turn up something quickly.
David

 

[ccoon520]

I know for checking the ride height they want on cars they'll take a piece of tubing and cut it to length and "install" it where the shocks would go for checking wheel clearances and stuff like that. You could probably do the same thing with the seat and set what you want the top of travel to be for your shock length. Then find a coilover system that would work.

I think spring strength might depend on how much usable travel your system has when installed. If it only moves 3 inches then 100lbs/in will result in you bottoming out every time you hit a bump unless you only weigh like 100lbs. I think a good place to start would be to find a system that when you sit on its equilibrium is somewhere like 40-50% compressed. That way if you hit a bump you don't break your back from the system bottoming out and don't get flung off the seat from an upward motion. As a quick sanity check for what you are doing remember F=-kx. F being the force exerted on the spring (in this instance your weight), K being the spring's compression ratio (lbs/in) and x being the distance it will travel.

So if I were to assume you weigh 185lbs, the suspended part of the seat is a guesstimate of 35lbs and the spring ratio is 100lbs then:

F=185+35
k=100
So 220lbs=-100lb/in*x
x=-2.2

It would move about -2.2 inches, or 2 1/4" downward just from you sitting on it. I would be ok with this if it had 5" of travel but might be hesitant at 4" of travel.

Granted this isn't exact because as a spring gets compressed its k value changes but this will get a good ballpark. Also keep in mind that if you weigh 260 and your wife weighs 105 and both use the tractor no matter what spring strength you use it will be wrong for one or both of you so maybe look for a happy medium skewing towards the heavier side a bit because a sudden stop hurts more.

 

[Lil Foot]

Hard to tell exact scale, but that looks like an EZGO golf cart rear spring might be in the right size range, maybe shortened. This is from the GXT804 Turf Truck, standard springs are made with thinner wire.

 

[RCW]

Thanks to you guys, I'm starting to get a handle on spring sources.

@bird dogger and @ccoon520 gave me some great suggestions.

I still need to confirm dimensions, but a place like this does single springs in a bunch of lb/in rates....It's a place to start.

King 3.0"x14" Coil Springs 200lb Rate (polyperformance.com)

The spring @Lil Foot showed might fit too, and I looked at the EZGO resources for suspensions. Tough part there was everything was driven by model and part numbers, and I couldn't extrapolate that from an old piece of Iron.

Ping mentioned an MX bike cross, and I saw some similar too....

The tough part is that for years, I could go through AGCO and get part numbers for a 70 year old tractor. AGCO is the parent company for a bunch of brands. It seems that's stopped, and is really bothersome to me.

I could take that old part number, and work to a modern day part number ....sucks that resource appears gone.....

Looking forward, I'm uncertain with the shock that goes inside the spring, and how to size and mount it. That will work out as I go on.

 

[wgator]

What about something like this seat shock absorber with spring at the following link: CLICK HERE.
7-5/8" center to center fully compressed.
10-1/2" center to center (of holes at each end) extended

 

[RCW]

An update....

That is a Knoedler Flote Ride seat...standard on many tractors of the era. Many different arrangements, but similar parts in some.

Lil Foot aka Bill may be the winner for compatibility...

Not the spring, but a rear shock from a Club Car is a match, with some re-working. One is on the way!

I'm wondering if Bill's spring could be a match also..

1988-Up Club Car DS Rear Shock Absorber At Buggies Unlimited | BuggiesUnlimited.com

I will get that, and work on the spring part....getting there.

My parts are all primed and painted.

I'll have more questions, but I'm getting some ideas how to put it back together. Great feeling. That thing was tossed in the manger of the barn 40+ years ago, and we lost some parts along the way.

 

[RCW]

Where I think I'll need more advice....

This is an Allis Chalmers WC picture from Yesterday's Tractor...parts are the same as mine, but different dimensions.

Notice the spring/coil assembly. At the top of the photo is a cylindrical rod that fits in the 2 brackets in the lower bracket.... 2 "U" shaped holders.... my lower bracket will take a 5/8"x 4 1/4" rod..

Should I just drill and tap a piece of rod and thread the shock into it, and add a lock nut(s) on the top/shock side? That's my theory so far.


Second, the cups for the spring are flat-topped and appear pretty stout/solid. I haven't seen a source for anything similar....ideas?

That's something I can't fabricate. I won't worry about those until I get a spring to fit them to..

After all that I'll have to figure out the top bracket to hold it all together and lock into the top side links of the Knoedler frame.

 

[Russell King]

Your top and bottom parts may be similar to McPhearson strut parts. You may look at suspension parts of Can Am three wheel motorcycle or small cars like a Smart Car or Fiat or Cooper Mini

 

[ccoon520]

Where I think I'll need more advice....

This is an Allis Chalmers WC picture from Yesterday's Tractor...parts are the same as mine, but different dimensions.

Notice the spring/coil assembly. At the top of the photo is a cylindrical rod that fits in the 2 brackets in the lower bracket.... 2 "U" shaped holders.... my lower bracket will take a 5/8"x 4 1/4" rod..

Should I just drill and tap a piece of rod and thread the shock into it, and add a lock nut(s) on the top/shock side? That's my theory so far.


Second, the cups for the spring are flat-topped and appear pretty stout/solid. I haven't seen a source for anything similar....ideas?

That's something I can't fabricate. I won't worry about those until I get a spring to fit them to..

After all that I'll have to figure out the top bracket to hold it all together and lock into the top side links of the Knoedler frame.

View attachment 60098



View attachment 60099

The question I have is, how confident of a fabricator are you? If you got a spring and the cups are you able to weld on the round bar stock to the bottom yourself and can you make that little saddle with the bar stock ears and weld it to the top cup?

If so then finding some rear coil spring retainer cups like this:

https://www.dennis-carpenter.com/tr...GVohLeCWtD-PRVBTCv8GXP1ON9Se8_p8aAmREEALw_wcB

Then taking and bending some 10-7 gauge sheet to the needed length and welding on the bar stock tabs to it on top and welding your length of bar stock on the bottom wouldn't be the hardest thing in the world.

Also if you are competent welding you can probably make your own cups the diameter and height you want by taking some 7 gauge sheet and some schedule 40 black pipe that is the ID you need and welding the 2 together. Then adding the bar at the bottom and the saddle at the top as described earlier and you'll have your spring assembly done.

If you use a metal hole saw (Milwaukee and Dewalt both make one) you'll get a perfect circle. Also doing it this way you can add a little bit of height insurance if you want so the spring doesn't bounce itself out of one of its cups.

It'd probably be a 8-16 beer job to fabricate the cups (including attaching the bar stock and saddle) depending on how quickly you drink beer, how hot it is that day and how cooperative the pieces are.

 

[RCW]

Your top and bottom parts may be similar to McPhearson strut parts. You may look at suspension parts of Can Am three wheel motorcycle or small cars like a Smart Car or Fiat or Cooper Mini

Cooper Mini parts are pretty close. Appreciate the help.

 

[RCW]

The question I have is, how confident of a fabricator are you?

It'd probably be a 8-16 beer job to fabricate the cups (including attaching the bar stock and saddle) depending on how quickly you drink beer, how hot it is that day and how cooperative the pieces are.

Confidence is something I have plenty of!

Unfortunately, sometimes it exceeds my skill-set.....

The Ford retainers are definitely workable, depending on ID.

Really appreciate your help with spring calcs, etc.

I will look at 10 gauge too.

I have a welder and many common tools.

I will get the frame reassembled and shock ready for use. Sounds like the shock studs need more threading, and shortened.

Then get a good idea of spring dimensions. Next step will be the cups/caps /retainers/plates....seems everyone seems to use different terms.

I’m really getting a good idea how to put this together....

When the time comes, I’ll take your advice and stock up the shop refrigerator.....

 

[RCW]

Similar to someone else’s AC WC picture I posted, so far so good.

Instead of replacing the bearings on the side links at $10 each, I pressed in $0.65 nylon spacers. Fit perfectly.

If they crap out, I’ll replace with homemade UHMW spacers. Stuff is indestructible. This tractor isn’t used 6 hours a day anymore.... but I’m 100 pounds heavier than my dad ever was....

2 of 4 zerks were broken. Will replace with 4 new ones.

I also cut a piece of 5/8” cold rolled steel for the bottom hold point of the shock/spring assembly. Thinking that will be drilled and tapped to mate with the bottom stud of the shock, outside of the cup/retainer to hold the bottom together.

These are the stock bearing and rod I cut.