Greetings,
I have a 1991 MTD lawn tractor 18hp w/46" deck, 6 speed, low and high range. Over the past year 1st through 4th won't move tractor forward and I have to use position 5 or 6. Is this a problem with the trans or a drive belt problem? The only belts that have ever been changed are the deck belts. Thanks for any help.

Greetings,
I have a 1991 MTD lawn tractor 18hp w/46" deck, 6 speed, low and high range. Over the past year 1st thru 4th won't move tractor forward and I have to use position 5 or 6. Is this a problem with the trans or a drive belt problem? The only belts that have ever been changed are the deck belts. Thanks for any help.
It sounds as if tou have what is called a Speed variator, There is a lever you move forward to increase speed without using a clutch? If so the drive or driven speed variators are stuck. Sounds complicated but not really. You need to get to the pulleys and saturate in a penetrating lube (WD-40), this will allow them to move freely. . It may take a little driving while moving the speed selector lever slowly from low to high and back again. You will get a lot of slippage at first due to the belts in contact with the penetrating lube and maybe some smell.

The pulleys change diameter by spreading apart and retracting depending on the speed selection, yours are frozen or at the very least not moving all the way. Most shops would disassemble and clean completely, but you will probably get lucky by lubricating the P**S out of them.

Good luck

Thanks for the response about my 1991 mtd. Actually u are supposed to use the clutch when changing forward speeds, sorry I left that out. Really appreciate your help as I got burned on a deck repair a little over a year ago. Got charged more to change out one spindle than I can by a whole deck rebuild kit for. That's why I was grateful to find this site and appreciate your help.

It sounds as if the model you own may still be a "shift on the go" and the solution still would work. Post the model# that would help.
Good luck and thank you for the rare response.

Thanks again! 1991 MTD Tradesman, GT 18/46
Model #422707
Type: 151001
Code: 91091632

Now my 1991 MTD Lawn Tractor, GT 18/46, won't go in any forward gear nor reverse.
Are the rear ends a rebuildable item?

Thanks for any help.
Walt

The transaxle is a serviceable item but very complicated. Make sure the pulley on top is spinning AND it is driving the shaft it connects to. It is not uncommon to loose the key that holds it all together. Instant message me, we can contact by phone so I can get a better Idea as to what we are dealing with.
Thanks,
Don

The model you gave previous is for the engine I believe and does no good for the tractor.
Regards,
Don

I have a tractor MTD Tradesman GT 18.5-46 Model 145S820H112, Serial Nr. 1I234C20157 and I need the service manual, where can I find it?