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L120 Blade Clutch......history of issues?

#1

B

bartles

I was given a L120, GXL120A014009 with a B&S Model 406777-0128-E1. It looks to be a rebuildable core: good compression, engine runs
relatively smooth, check the cam lift(s) for worn lobes and the transmission works fine. The 48" deck was not installed but has good metal. I have a couple of questions I would appreciate getting info on:
1. The previous owner has replaced the blade clutch 4 times since the mower was new(July 2003)hour meter indicates 651 hrs. Does this model have a history of blade clutch issues?

2. The owners manual describes a "brake in" procedure ...cycling the clutch off and on for 12-15 cycles so to get it "properly burnished".
This is a new one on me...not doing this initially after each clutch replacement could this perhaps the reason for so many clutches?

Thanks in advance,

bartles


#2

M

mechanic mark

Yes is answer to question.
Not all manuals include PTO clutch burnishing & checking clutch air gap with feeler gauge.
Use OEM JD Parts for best results.
Manual above is loaded with information necessary for the DIY'R.


#3

B

bartles

mechanic mark said:
Yes is answer to question.
Click to expand...
Thanks for the info.... so if the owner had ready the manual there would have been more vacation money?😝


#4

I

ILENGINE

I have seen my fair share of electric clutches on the L series short and take out the pto switch at the same time.


#5

B

bartles

ILENGINE said:
I have seen my fair share of electric clutches on the L series short and take out the pto switch at the same time.
Click to expand...
It is unusual to go through so many clutches in that short period of time. Not doing this burnishing procedure may be the very reason why.


#6

I

ILENGINE

bartles said:
It is unusual to go through so many clutches in that short period of time. Not doing this burnishing procedure may be the very reason why.
Click to expand...
My customer a few years back with the L120 went through 4 in 750 hours. first two were replaced under warranty, and I did the last two replacements and did the burnishing before they left the shop. I could see lack of burnishing leading to slippage and wear, but in these clutches there were burning out the coils and shorting to ground.


#7

StarTech

StarTech

Nearly every PTO I have seen shorted where make with enamal coated aluminum wire. Many of the newer PTO clutches have gone back to enamel copper wire.


#8

B

bertsmobile1

JD specify a lower viscosity oil in their transmisions .
Most of them start to go at around 1000 hours
So if you now own this mower and it has a hydro tranny pull the transmission out then drain the oil and replace it with 20w50 fully synthetic engine oil.
That should give you another 500+ hours from it
You test a hydro by parking on a hill, turning the engine off and giving the mower a push.
If the transmission is very good then it will be hard to push and stop the instant you stop pushing
If it is just about to turn it's toes up it will race away down the hill like Mulga Bills Bicycle

As for the clutch you should be able to get a better quality aftermarket clutch .
Were possible I fit X-tream clutches which I have found to be a cut above most others .


#9

B

bartles

bertsmobile1 said:
JD specify a lower viscosity oil in their transmisions .
Most of them start to go at around 1000 hours
So if you now own this mower and it has a hydro tranny pull the transmission out then drain the oil and replace it with 20w50 fully synthetic engine oil.
That should give you another 500+ hours from it
You test a hydro by parking on a hill, turning the engine off and giving the mower a push.
If the transmission is very good then it will be hard to push and stop the instant you stop pushing
If it is just about to turn it's toes up it will race away down the hill like Mulga Bills Bicycle
Click to expand...
🤣🤣🤣, Well it didn't run away quite that fast! Changing the oil and cleaning the magnets is in the plan for sure.

bartles


#10

B

bartles

ILENGINE said:
My customer a few years back with the L120 went through 4 in 750 hours. first two were replaced under warranty, and I did the last two replacements and did the burnishing before they left the shop. I could see lack of burnishing leading to slippage and wear, but in these clutches there were burning out the coils and shorting to ground.
Click to expand...
Did it make a difference when using aftermarket clutches? What brand did you use in the replacements?

bartles


#11

B

bartles

StarTech said:
Nearly every PTO I have seen shorted where make with enamal coated aluminum wire. Many of the newer PTO clutches have gone back to enamel copper wire.
Click to expand...


#12

B

bartles

Thanks... When I checked the wiring out it did look like it had gotten a little warm. The insulation was baked hard in a few places between the clutch plug in and the harness connector that sits in the frame behind the engine, frame level.

bartles


#13

StarTech

StarTech

Then the PTO field winding have shorted out in the past. I have seen clutches to short out partially and pull up to over 16 amps but still work until something else fails.


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