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Discussion Starter · #1 ·
Hi all, recently picked up an old mower that needs some work (model 138-342-680) I've never had to play with a mower so figured I'll hit the books before tearing it down.

The main issue is that it's stuck in forward, you can move the stick to neutral and reverse but it doesn't get out of forward gear, on top of this the linkage for the speed control free floats between 3-7th as the mechanism underneath doesn't adjust between those gears. I cant help but think they are related and as I said above I've got 0 experience with mowers, any advice much appreciated.

Supplied some photos for easier ID of the offending mower. Last photo is me trying to explain where the linkage free floats, it moves vertically down the guide, while mechanism underneath is getting stuck after 2nd gear as though it's meant to be spring loaded but hasn't got the spring thus not engaging properly? I tried moving the mech underneath by hand with lever in 7th but it still wouldn't move as well.

Thanks.

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That's a varidrive system and with no experience with mowers you may be in over your head. The transmission is single speed. The lever on the left fender is attached to a small rod that moves in/out of the transmission to ger f n or r .If only getting forward the shifter may be detached from that rod. Or there could be internal issues.
The speed lever is even more complicated. It works with a dual vari-drive pulley which is driven by a belt from the engine pulley to it's lower groove and the upper groove drives a second belt o the transmission pulley. The varidrive pulley is attached via a moving bracket which is controll by the brake/clutch and the speed selection lever.
go here
enter 138-342 as model and just 1 as serial and you can download your manual and see the stuff.
 

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Discussion Starter · #3 ·
That's a varidrive system and with no experience with mowers you may be in over your head. The transmission is single speed. The lever on the left fender is attached to a small rod that moves in/out of the transmission to ger f n or r .If only getting forward the shifter may be detached from that rod. Or there could be internal issues.
The speed lever is even more complicated. It works with a dual vari-drive pulley which is driven by a belt from the engine pulley to it's lower groove and the upper groove drives a second belt o the transmission pulley. The varidrive pulley is attached via a moving bracket which is controll by the brake/clutch and the speed selection lever.
go here
enter 138-342 as model and just 1 as serial and you can download your manual and see the stuff.
That manual definitely helps! Looks to be either going to be a pins dropped at some point or a spring has broken/stretched. Simple enough stuff seeing it there it makes sense now. I don't have it on my premises currently so I can't exactly sit there and look at it. Looks like I'll take the deck off and sus that varidrive out, in which the same time the transaxle can be looked at and removed if need be anyway. 2 birds 1 stone
 

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First thing I do when starting work on a tractor, is what you did, is get the service tech manual. Search youtube for someone who has already invented the wheel..LOL You may find someone who has experienced the same situation and shows you what they did.

Like This Guy

Hope the problem is external to the trans as opposed to internal.

You've taken a big first step by posting here on MTF within the correct forum.

Don't start doing too much on the problem until you do your research.

Spend time working on other areas, like the motor.

Clean the machine front to back as it's much easier to work on it clean.

Find out what other models used the same format as that tractor. A lot of tractors are very similar except the body. Same engine, trans, electrical, etc., just different appearance/name.

Keep your eyes open for a cheap parts tractor. One that has parts you may need that someone just want to get rid of cheap.

Check withing your sphere of friends and see if any have experience working on mechanical equipment. (DIY guys)

Be patient as parts, information and possible help from someone can pop up when you least expect it/

After spending time researching/learning decide if this project is something you really want to commit to. If you commit then just be confident the you will make this tractor come back to life.

Once you start working on it you can become obsessed and possibly loose your marriage, home, alienate all your friends and ultimately become a shell of the man you once were...LOL

It will start when your dreams are taken over by lawn tractors...LOL
 

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first thing I do with any vari-drive setup is pull the pulley off and clean it... they are notorious for getting sticky or even seizing completely with rust. They are also known to be very picky about the two drive belts so its best to get new factory oem replacement belts.
 

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Discussion Starter · #6 ·
First thing I do when starting work on a tractor, is what you did, is get the service tech manual. Search youtube for someone who has already invented the wheel..LOL You may find someone who has experienced the same situation and shows you what they did.

Like This Guy

Hope the problem is external to the trans as opposed to internal.

You've taken a big first step by posting here on MTF within the correct forum.

Don't start doing too much on the problem until you do your research.

Spend time working on other areas, like the motor.

Clean the machine front to back as it's much easier to work on it clean.

Find out what other models used the same format as that tractor. A lot of tractors are very similar except the body. Same engine, trans, electrical, etc., just different appearance/name.

Keep your eyes open for a cheap parts tractor. One that has parts you may need that someone just want to get rid of cheap.

Check withing your sphere of friends and see if any have experience working on mechanical equipment. (DIY guys)

Be patient as parts, information and possible help from someone can pop up when you least expect it/

After spending time researching/learning decide if this project is something you really want to commit to. If you commit then just be confident the you will make this tractor come back to life.

Once you start working on it you can become obsessed and possibly loose your marriage, home, alienate all your friends and ultimately become a shell of the man you once were...LOL

It will start when your dreams are taken over by lawn tractors...LOL
I did see that video and its in my list of to do's! Always do research first, I've learnt that from my car collection lol.

I seen a video on transaxle strip down a rebuild/regrease is simple enough just time consuming to do.

I degreased it as soon as it was off the trailer, its fairly clean as is however. Only other thing that needs to be done to it is the headlight housings have melted at some point so need to find some replacements and exhaust puffs a bit of black when rev up however previous owner apparently rebuilt carby, which it does look like new and he gave me the housing of the donor carb he used, I'd say its a tune issue. Apart from that I got a replacement seat already from a more modern mtd we have. So really there's not much to do other then the direct issues.
 

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Discussion Starter · #7 ·
first thing I do with any vari-drive setup is pull the pulley off and clean it... they are notorious for getting sticky or even seizing completely with rust. They are also known to be very picky about the two drive belts so its best to get new factory oem replacement belts.
Figured that may be the case! They'd cop everything yet never get cleaned out, I'll see if I can't find the correct size belts and grab them before the weekend, if I had to pull it down to the point the belts had to come off new ones were going on anyway, screw doing that twice.
 

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Discussion Starter · #9 · (Edited)
Figured I'd have a play today, found the forward/reverse shaft working fine, variable working as it should however needs adjustment however the worst of it today is I'm now not getting spark, swapped in a 13.5hp motor and it as well is not getting any spark, the wiring is getting power all up to the coil however no spark is being produced, before installation we hotwired the 13.5 and it sparked, so really there is no reason it shouldn't? Would they have different pulse modules up the back that could cause conflict?
 

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There is no such thing as wiring getting power up to the coil. Coil has 2 wires. High tension to sparkplug and small wire is kill wire. Grounding that kill wire is what stops spark. It may be grounded as it passes back to keyswitch. Disconnect the small wire from coil and test again for spark.
 

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Discussion Starter · #11 ·
There is no such thing as wiring getting power up to the coil. Coil has 2 wires. High tension to sparkplug and small wire is kill wire. Grounding that kill wire is what stops spark. It may be grounded as it passes back to keyswitch. Disconnect the small wire from coil and test again for spark.
Ah yes I did that however still no spark, and I grounded the plug to the engine also. I found the 11hp coil to be cactus as the casing had split so got another on the way however the 13.5 was tested still fine yet won't fire/give spark on this mower, the ignition switch was redone by previous owner and found the wire running to alt loose and corrected that, still not explaining why 2 engines don't get spark but crank however. The ground wire runs from the coil to a plastic clip on the throttle linkage then bridges into negative on the ignition switch, the white wire is the one I found loose.
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get an inline spark tester. leave plug out for easy crank . Attach inline tester to coil plug fire and other end to ground. Remove the kill wire from coil (right at the coil). Crank and see if spark. If none coil is bad. If same on both 11 hp and 13.5 there's a chance an incorrect key switch has passed 12v to both your coils and burnt them out. Trace your coil kill wire back to the keyswitch. It should be connected to the tab labelled M.
 

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Discussion Starter · #13 ·
I have traced it back and it does go to the M terminal and is secure, would a spark plug or screwdriver grounded not essentially do the same job as a dedicated tester? Voltage wise to the coil looks fine when I threw the multi on it 0.05v or something. Next to nothing.
 

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there should be no voltage to the coil. where are you measuring that? the inline tester is good as a starter since there's certainty that if coil can't jump it's gap to ground then it's dead. A weak coil may actually pass that test but won't spark a plug, especially as an installed plug is affected by the compression. So be sure your plug is good. By grounded screwdriver I assume by your picture you mean it's in the sparkplug boot and held close but not touching a grounded metal part of engine?
 

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Discussion Starter · #15 ·
there should be no voltage to the coil. where are you measuring that? the inline tester is good as a starter since there's certainty that if coil can't jump it's gap to ground then it's dead. A weak coil may actually pass that test but won't spark a plug, especially as an installed plug is affected by the compression. So be sure your plug is good. By grounded screwdriver I assume by your picture you mean it's in the sparkplug boot and held close but not touching a grounded metal part of engine?
I tried 3x spark plugs and the screwdriver, measured resistance not voltage sorry with multimeter. I've ordered a new one today to truly phase it out. If that is the case I've had 2 coils go at the exact same time on two engines, we shall see.
 
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