John Deere SST

Discussion in 'Homeowner Assistance Forum' started by Scott99, Oct 6, 2002.

  1. BruceDK

    BruceDK LawnSite Member
    Messages: 1

    Steering in reverse stopped suddenly on my SST after mowing some tall weeds. Thanks to your site I got some clues where to look. Lo and behold one of the plugs behind the right rear axle was dangling loose. Plugged it back in and away I went! :cool2:
  2. ktaugher

    ktaugher LawnSite Member
    Messages: 1

    Thanks to everyone for posting!

    Lost steering response on my SST-16, forward and reverse, due to a bad voltage regulator. This is a Briggs & Stratton part (by the way, B&S no. 394890, JD No. LG691185 (which my local dealer had) but note that the JD website says that "LB691185 has been replaced by MIU12514" $92 on 28 August 2009. Ebay for $50.

    If you're getting a steering problem concurrent with a dead battery, I'd consider testing and/or just replacing the voltage regulator. I suspect it's a chronic problem, because my JD dealer's parts mgr. said he had them in stock before I even finished reading him the part number.

    5 minute job, the voltage regulator is bolted to the right side of the engine shroud, just behind the right cylinder. It's a square aluminum block, with a pair of yellow wires and one red wire coming out of a block of expoxy potting compound.

    My battery was intermittently going dead, I thought it might have been the ignition switch not going completely off. I started taking the key out, to make sure my knee wasn't turning it partially on when I climbed out of the seat. This 'seemed' (ha ha) to work until a few days ago.

    It wouldn't start, so I had to jump start it, and after about 45 minutes of mowing the steering stopped responding. I let it sit for a few minutes with the engine running, and the steering came back to life for about 60 seconds, enough time to get it in the shed, but not to park it.

    I went on line and found this forum, and saw voltage regulator, vacuum leak, or bad switches as possible culprits. Since I had the battery charging problem, I got the voltage regulator first. The steering has to have electricity to actuate the hydraulic system.

    This morning I replaced the regulator, hooked up a 4 amp charger to the battery, and let it sit for about 4 hours. Then I tried it, it started right up, and steering was as good as new.

    Hope this helps someone else out.
  3. namosi

    namosi LawnSite Member
    Messages: 2

    it even helped a SST16-owner in Germany. :germanflag:

    Thank you guys!
  4. ccecilm

    ccecilm LawnSite Member
    Messages: 48

    Thank you for posting your experience. I'm sure it will help others in the future since people that have troubleshooting knowledge on the SST are pretty scarce.
  5. ccecilm

    ccecilm LawnSite Member
    Messages: 48

    How did you go about testing the voltage regulator or did you just put on a new one without testing the old one? Please reply, I need to know because I may have the same problem but hate to just start throwing new parts at it.
  6. ccecilm

    ccecilm LawnSite Member
    Messages: 48

    Never mind, I found it:

    If you have a volt=ohm meter, you can check the voltage of the battery with the engine off.

    Then start the engine, and recheck voltage. If voltage hasn't increased to about 13.5 to 14 volts, charging system needs to be checked.

    You can check the the stator voltage by unplugging the connector that comes from the engine that connects to the regulator. Set you meter to AC volts, start engine and run at full speed, voltage should be about 20 volts AC. If it's not, then the stator is bad. If you have 20+ volts AC then stator is ok.

    Voltage regulator/rectifier can be checked by reconnecting stator and running engine full speed and checking voltage at the orange wire and the yellow wires. You should have 13+ volts DC at each wire, if you do not, replace regulator/rectifier.
  7. ccecilm

    ccecilm LawnSite Member
    Messages: 48

    Well, the above is certainly NOT correct for my SST16; It has 2 yellow wires coming from the stator and 1 (one) red wire coming out of the regulator/rectifier.

    The previous post may apply to the SST18 but I can not confirm because I do not have one.
  8. Shifty937

    Shifty937 LawnSite Member
    Messages: 1

    Well I happened to stumble upon this thread and lots of good advise here on the SST. Thx everybody, anyhow this past weekend I went to go look at an JD XL172 about an hour away. Pulled into the drive and a guy was loading it up and the guy said I just sold it. Very disgruntled to put it mildly, I let him know I wasnt happy. So the guy says tell ya what, I do have another JD riding mower if your interested. Im like yeah ok, so went to his garage pulled of the tarp and low and behold a SST18 with missing hood non the less in nice condition with 400 hours runs exelent. Guy says $200 bucks its yours ill deliver it for $20. Feel like a thief, but hey...... :usflag: :hammerhead: Same price as the XL172 which needed quite a bit more work to the deck and some other things.

    So now im a proud owner one these Deere's, my question is that it seems so slow. Like the pedals are binding up in the linkage and are hard to push and hold and if I push to hard at just past half pedal the motor cuts out and wants to die unless I let off, in forward or reverse. Also think it is having the very same charging issue that seems to be a big problem on this thread.

    I notice it has a shock attached to the linkage, and the pedals dont return fully to there neutral position. I busted out the the can of PB BLaster soaked it down before work to return with the same problem. Is there some kind of adjusting it may need ? Yes the steering works great. Until just bit ago no steer in reverse. Please help, my grandma could out walk this thing. Anybody have a complete hood assembly also ? Also need a seat.

    YBNORMAL LawnSite Member
    Messages: 2

    New user here, I thought I would post some thoughts about my SST16. As you all know there is not to much information out there about how these things work.

    The information in this thread has been great, and to add to it:

    The way this thing works is that as soon as you touch the forward or reverse pedal, the switches in the back tell the tractor which actuator to collapse. The actuators do not control the steering per se, they just position the mechanical linkage so that the wheels turn properly based on forward or rearward movement of the tractor.

    For example:

    lets say you are making a slow left turn moving forward, (for simplicities sake) the tractor would be moving counterclockwise as viewed from above.

    Low lets say you are making the same slow left turn but in reverse, The tractor should rotate in a clockwise direction from above.

    Without its compound linkage the tractor would steer like any other tractor in forward, but the wheel would have to be reversed in order to make the SST behave like a normal steering tractor in reverse (left turn in reverse makes the tractor rotate clockwise on any other tractor with steerable front wheels but the SSt front end would go left when backing up with its wheel to the left). People already didn't like how the SST steering felt, imagine if they would have left out the compensating linkage :laugh:

    You will notice this linkage is hooked to the trans in the same place that the bolt is, that adjusts the straight line tracking of the tractor (the relationship of one axle speed to the other.)

    You can watch the linkage do it's thing if you have the fenders off, put the tractor in park, key off:

    1:turn the wheel left or right, the linkage going back to the tranny will not (should not) move yet since the actuators have not been told to set up for forward or reverse.

    Now, simulate a pedal input (actuator movement) by taking the part of the linkage that the actuators are connected to and move it to the right of the tractor (I believe this to be the "forward driving actuator" but I am not sure, my motor is blown and I am waiting for another :)). While holding the actuators to the right side of the arc, turn the steering wheel to the right, now you will see the linkage going back to the trans pulls forward, likewise a left turn on the wheel will move the trans link back.

    2:Now push the actuators to the left of the arc, and again turn the wheel to the right, now the linkage moves the trans lever back, likewise a left steering imput moves the trans link forward.

    This linkage essentially takes the place of what your brain would be doing on a standard zero turn that has levers that you push forward to go straight, right lever forward to make a forward left turn and right lever back to make forward right turn, or any combination of the above to make the zero turn do what you want.

    A standard zero turn has a direct link to each side of the trans for both steering and forward/back motion control, simple really, steering is done by your brain adjusting wheel speed left to right. The SST has a forward/back lever on the left of the trans right near the actuator switches that is mechanically linked to the forward back pedals. While at the same time it has another mechanical link that controls the relative wheel speed left and right wheel.

    My SST would zero turn in reverse all day long, but I had to be on the forward pedal pretty hard to get it to start steering in forward, at that high of a speed, it would not "zero" turn on a dime but would turn at normal mowing speed. I was able to get buy, but it was annoying. I was not real sure what was doing what under there till I read this thread and put some things together in my head while looking under the hood of mine. Waiting for my new-ish motor :).

    I found that the switch tabs on my SST16 had bent slightly (probably from the pivot points not being lubed well, or grass wedged in there), and I could not get a setting on the forward switch per the advice in this thread.

    So I got that all squared away, also the last time I had the fender deck off when I bought the thing two seasons ago, I sprayed the actuator bellows with WD40 after reading what little info was out there, saying that they get brittle and crack then wont hold vacume. I am happy to report that mine are still nice and soft and I hit them again with some spray lube to keep them supple.

    I hope I explained clearly so that other can understand the voo-doo of the SST16. It really is not very complicated once you know how things work on these tractors.


    YBNORMAL LawnSite Member
    Messages: 2

    As far as the speed thing goes, I had a similar problem and found that the main belt for the tractor was out of adjustment. The parking brake pedal does two things, it puts slack in the belt so the engine cant turn the trans pulleys. The second thing it does is physically lock the trans with another linkage running back the left side of the frame.

    There is a tensioner attached right after the park pedal, so when the parking brake is off it is sprung and keeps tension on the belt. It only has a certain amount of throw in order to keep the belt tensioned. I thought my belt was stretched too much, BUT, there is another idler pulley that you can move fore or aft in order to get the belt tensioner in it's range of motion. It is a plastic pulley if I remember correctly and it sits just about right in the middle of the tractor and has a metal tab that keeps the slacked out belt on, it's shaped like a "V".

    I would start there for the speed issue. The linkage for the pedals is not real complicated. The forward pedal linkage is not adjustable, it will throw as far as that "shock" you were talking about will let it. BUT, if the reverse pedal is not right it will not let the forward linkage go all the way. When it is right, the forward linkage will bottom out the shock, the reverse pedal linkage will be a little loose. When hitting reverse, the throw at the trans is very small and the linkage will actually bow if you push too hard on the pedal. If you try to adjust the bow out of the reverse rod, you will start to limit the travel of the forward pedal. Thats how mine was anyway. Try lubing the pivot of the pedals, That helped mine quite a bit.

    I don't know why the engine would die mid pedal like that, sounds more like an engine problem than a linkage or tractor problem.


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