OutdoorKing Repair Forum Forums Repairs and Maintenance Questions On Ride On Mowers Questions On Ride On Mowers Frames Project-mtd 12.5 briggs twin ride on

Hi guys/gals,i did a deal with a bloke and picked up a mtd,it has a 12.5 hp twin cylinder briggs-7 speed box plus reverse-head/tail lights and a side throw rear catcher(thats why i got it)problems-siezed front wheel-flat tyres-grass bags have holes-not run for 2 years.removed water from tank and carby-fuel pump/cleaned and repaired all safety switches-installed battery-turned the key and she purrs like a kitten,switched off ign and the engine kept going so i disconnected the battery-motor kept going,blocked of choke to stop the motor.not to worry.will post pics tommorrow on progress...ken

mower man,

Sounds like you have a bad earth somewhere. I would be checking and cleaning your earth wire and trying again.

Something is keeping the kill wire from being grounded when you switch off. Could be the wire itself is disconnected or cut, or it could be in the associated wiring around the start-stop switch or solenoid. Following Bruce's diagnosis will probably fix it of course, but if it doesn't, trace the kill circuit and test each section. Sometimes amateur tinkerers working on it previously have done bad things to the safety circuits, and after that you are lucky if anything works.

Hi guys,i found the problem with not being able to stop the engine-there is a seperate push button STOP switch,so you turn the key to "off"and then push the button.the pto switch works,the "off the seat"switch works as does the clutch switch.strange thing-when the motor is going and the pto(blades)are turning,when you select revers gear the engine stops.there is a switch at the reverse selector so i might make this into a reverse beeper.any way here are some pics if they work...ken

mtd model 139-684-670
date fo69h
engine vanguard 480x 12.5hp v-twin

Ineed advise on how to get the blade pully off so i can put new bearings on the shaft.i did one today R/h side using my mates press.every thing was well stuck even after soaking for two weeks with wd-40,but the left hand side wont budge.i even tried boiling it in water on the bbq to heat up the steel but to no avail,i have new bearings to install and two new blades.i would like to mow someones grass to give it a go using the catcher-then i can take it off the project list.any tips would be gratefull...ken

The first step is to look at the one you did manage to dismantle to see if you missed something - unless it is rusted it shouldn't be that hard to take apart. I can't tell much from the picture except that one has a retaining nut, and the other doesn't. I take it the one without the nut is the one you are trying to dismantle, and you've already removed the nut.

It looks as if you begin by removing the V-belt pulley. If it was held by a nut, it must be capable of sliding off, or they wouldn't have needed the nut. Can you fit a split plate under the pulley, so it bears close to the shaft, not near the outside of the pulley, and press it off? You may need a special split ring, to make it bear in the right place on the underside of the pulley. This would be a small lathe job. Don't let the split ring bear against the outside of the pulley, you'll just crush it.

Once you have ensured there is no secret retaining device we don't know about, it is just a matter of supporting the underside of the hub of the pulley, and putting ten or fifteen tons on the shaft with a good press that pushes square to the split ring. It is good practice to put a piece of aluminium between the press platten and the end of the shaft, so the shaft doesn't deform. When the shaft moves the length of the threaded part, you'll need to use a piece of axle-sized steel bar with square ends, in between the platten and the end of the axle so you can continue to press the axle downward. Aside from having to make the split ring if you don't happen to have a suitable one, it is routine.

Up date,re-fitted L/h shaft and blade and fitted the retaning nut.drove around for about 2 hours mowing the council grass to test the mower before i take it on a job.nice roar with new blades and both catchers filled up.when my daughter was driving away from me i could here a rumble like a diff noise,so does my diff take oil or is it packed with grease and with my model numbers in post 19462 in this section can some one(bruce)clarify what they mean so i can order some steering parts etc...ken

ken, you said you were going to disconnect the reverse switch that apparently prevents you from shifting into reverse without stopping the engine first. My guess is that the manufacturer included that feature for a good reason, and you'd be better off keeping it. Some gearboxes are stronger than others. If you made a gearbox that was a bit flimsy, and you found that when people shift into reverse with the engine revving and the clutch dragging, they pull the reverse idler shaft right out of the housing, destroying the housing in the process, what would you do? I suspect one of the things you'd consider is making them stop the engine before they shift into reverse.

I don't know that is why that reverse switch is there, but if it were my mower, I'd be leaving it there and being rather careful of the reverse gear.

Hi grumpy,i totally understand and did not think about the strength of the gear box but when you are mowing in forward and you need to go backwards a few feet(meters) its a pain in the but to disingage the blades then re-engage to go forward.i was thinking mainly about the force you are putting on the blade belt and the blade pully brakes.you have a point though so i will re connect the switch and try to mow smartly in a forward motion and clean up bits i miss with the push mower.thanks for your input and could of saved me a lot of dollors by not destroying the gear box...ken

Also while im here the mower has 7 speed but the actual gear/diff is only 1-forward and 1 reverse.speed 1-2-3-4 dont work but 5-6-7(the fastest)work fine,exciting in reverse any way what do i need to look at to rectify this...ken

ken, if you can find the mtd model number on the mower and post it here, we can try to find a manual and get specific about what is happening. Generically, it sounds as if either your transmission shift linkage is jammed/bent/broken/out of adjustment, or the selectors are jammed or worn inside the box. It needs to be fixed, or you will end up using clutch-slip to do the job of the gearbox. It seems to be a decent mower, its best to get it working properly so you can rely on it in future.

I have a WHITE / MTD ride on that looks just like your mower except for the colour of it.
Mine is a twin cylinder 12.5HP Briggs with 7 speeds.
I rebuilt the MTD transaxle in mine as it was a bit noisy.
I replaced some worn bushes and repacked it in grease. It's now running a lot better.
The transaxle in mine is only one gear forward and reverse.
You actually get the 7 speeds with the variable speed pulley set up.
Maybe your belt is worn and may need replacing.

Murray, does it use a pair of variable diameter V-pulleys to get the speeds? If so, the gear selector linkage must control the diameter of the master pulley. In other words, if it works as I'm visualising, it sounds as if the problem is either a linkage adjustment, a jammed expanding pulley mechanism, or a worn belt that limits the possible range of pulley size.

ken, does your mower have a variable ratio V belt drive like Murray's?

As I was getting the full seven speeds, I didn't have to do any adjustments to this setup.
All I had to do was remove the belt from the transaxle pulley.
From what I saw at the time, what you have described is how it works.

Hi grumpy,have a look at post 19462 the specs are there and murray i will replace the drive belt then i can have the old one as a spare and also i need to adjust the brake.i did look at the mtd/white manual in this section but it is slightly different...ken

If the speed control lever moves through its full range, it does sound as if your problem may be just a worn belt. I'm told they are a wearing part that needs to be replaced fairly regularly, especially if you operate the mower under dirty/dusty conditions. From time to time the pulleys will have to be replaced also. I suspect that belt drive mowers are best used on continuous green grass, not paddocks or grass with dirt patches.

Hi Ken,
The manuals I have did not come from this site. I found them else where on the net. They took a lot of searching to find.
I have both the operators manual, which shows how to make all the necessary adjustments, and also the parts list with exploded view.
I'm more than happy to send you a copy if you like.