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MM1 doesn't go on truck right

Discussion in 'Fisher Engineering Discussion' started by MeMeYuYu, Feb 16, 2011.

  1. MeMeYuYu

    MeMeYuYu Junior Member
    from USA
    Messages: 4

    The pins are too tight to go in without a hammer and the chain doesn't slacken enough when I try to mount my recently purchased used MM1 plow to my 04 GMC. In order to get the pins to line up I have to use a floor jack to lift things up enough to level the plow to truck frame. This is an older MM1 plow with diecast pump and electric controls. Wired it & put new push plates on my 04 GMC half ton. Plow came off a 07 chevy half ton but is older than 07.

    I took the pins out and tried them in the push plates and thier plenty small enough. I wonder if the new push plates don't allow enough space for the plow to sink in deep enough to align the pins.

    Currently the lift ram stops as soon as the plow touches the ground leaving no slack in the chain when I dismount the plow. Is the ram suppose to drop further so the chain is slack? If so what mught be the problem. There isn't any rust spot where it stops. I can see that some one has pried on the upper bracket with a bar.

  2. quigleysiding

    quigleysiding PlowSite.com Addict
    Messages: 1,129

    If I were you I would try to get it on the truck and then adjust the lift chain. If you don"t when you plow down hill you won"t even reach the ground. Also you need that slack in the chain so the plow the plow will mount right. The piston should be up at least an inch when you drop the plow sometimes more. Mine is like two inches, Then push it down before you dismount . Hope this helps. Welcome to Plowsite
  3. 06Sierra

    06Sierra PlowSite.com Addict
    from Maine
    Messages: 1,329

    MM1 will stop when the plow hits the ground. Hold down for a second to get it into float mode, get out and push the triangle all the way down by hand. That will get you enough slack.

    Here is what I do to take mine off, once the lift ram is all the way down:

    Drop the jack, I use a 4 foot pry bar and put it over the a frame and under the lip next to the jack leg. Pry down to try to get the jack in the next hole up. If it goes, good, if not not big deal. While pushing down on the pry bar I pull the pin out, and repeat on the other side. Pushing down like that takes the tension off of the pins and you can easily pull them out. I unplug the wires, and take the slack out of the safety chain and back away.
  4. MrPLow2011

    MrPLow2011 Senior Member
    from Boston
    Messages: 276

    :laughing: Everything you posted is normal for the MM1. Make sure when you drop plow to push ram all the way down.. A shoulder under the light will make pin drop in easier. But its normal to have to fight with it. Wait till you drop it on frozen ground and have to hook it up after a thaw :laughing:
  5. Mnpowerstroke99

    Mnpowerstroke99 Member
    Messages: 82

    Make sure before you take it off the truck to put it in float mode and then pull down on the lift chain until the lift cylinder is bottomed out.There should be some slack in the chain if not you have to extend the chain a little bit,otherwise it will be a pain in the a** to remove and install.To remove the plow, pushup on the head gear and pull the pins to release them.To install it,drive into mount,release the pins and push up on the head gear and they should snap in,raise the jack ,hookup wire connectors and your done.A little grease on the pins will also help them slide in and out easier.
  6. justme-

    justme- 2000 Club Member
    Messages: 2,138

    Yup- typical of MM1 - no need for a pry bar to lift the headgear to get another jack hole- just push back on the headgear like the other guys are sayin- shoulder under the light mount and rock it back toward the truck and you'll get into the next hole on the jack leg.

    Same for when putting on the truck- drive into the headgear and release the pin you're next to (driver usually) then shoulder under the light bracket and rock toward the truck and the pin will pop into place as long as the truck is far enough into the gear and straight on with the headgear. Repeat on the pass side then (and this is important...) lift the jack leg and plug in the wires.

    FWIW ALWAYS lift the jack leg when the plow is attacked for any reason- even if it's to test the elec connections or something where you will not be intending to move the truck because you will forget the leg is down and try driving away - and it's expensive to repair the leg brackets these days.

    There always seem to be a large number of comaplaints about MM systems being difficult to work- I liked the old Speedcast setup- hook the chain, lift the blade a little, swing it on the chains and pop in the pins - done in under 2 minutes. the MM took me a long time to master - most of my complaint was getting lined up since the Speedcast didn;t need to be - but now I'm pretty good and can usually drive right in. Takes under 2 minutes at worst and normally under a minute.
  7. MeMeYuYu

    MeMeYuYu Junior Member
    from USA
    Messages: 4


    Yesterday I locked myselfe out of the truck, at the store, w/engine running. Fun, Fun! So I haven't gotten to using your advice yet but thank all of you so much for your help. It's my first plow so you have helped a lot!
  8. MeMeYuYu

    MeMeYuYu Junior Member
    from USA
    Messages: 4

    IT WORKED!!. I followed your advice. I also removed the pins and reground the taper because there were ridges in them. The set up was still very tight so I ground about 1/32 off the rear of the plow assembly. Greased everything and it all worked like you advised. Push the ram down, lift with shoulder & click - pins went in.

    A big thanks to your all!!
  9. justme-

    justme- 2000 Club Member
    Messages: 2,138

    Glad you got it- BTW I know there have been several tips on here on lining up and tho I have not used them, I do have a bug shield on the truck and have thought about putting a small strip or tape on the back of the shield and matching on the back of the headlight so they line up from the drivers seat.
    So far I line up and then shift a little further left then I thing I need to be and I'm within 1 inch most of the time.