backlash on m35a2 pto

[baxter]

I installed my winch and pto last weekend and was wondering how you guys are checking the backlash on the pto.I was not able to get the dial indicator in.
Vaughn

 

[DanMartin]

I just felt in through the inspection plate...if the driven gear moves back-and-forth a small amount, the lash is "good enough". A slight bit too lose is better than a little too tight.

This is how multiple people told me to do it, and it seems right. Besides, it's not like there is a lot of options on shimming...just use the thick gasket and make sure the driven gear has some play against the drive gear.

 

[baxter]

That is what we did just removed gaskets until it felt right .It does operate nice and is quiet . I just wanted to see how others had done it. Thanks for the help

Vaughn

 

[gringeltaube]

Totally agree with Dan!
And if you don't want to pull that nicely sealed PTO inspection cover or even open the tranny's top cover... there is a little trick that always worked well for me: one can actually see both gears (reverse idler and PTO input) and how much play there is, if a (AAA) mini- or a AA-Maglite (with lens head removed) is introduced an inch or so into the oil level inspection hole, then look trough the oil drain hole while rocking engaged PTO back and forth at the output flange.

G.

 

[Recovry4x4]

Great shortcut Gerhard. I like that one!

 

[MikeON]

You guys that can reach the innermost gears on these PTOs to feel the amount of gear lash must have extra long skinny fingers. I could barely reach it with the PTO off the truck. Couldn't reach it at all with it mounted to the transmission and the frame in the way. I ended up making a mount for a long-stem indicator. You could just read it with it mounted to the truck. I had .009" of travel with 1 gasket.
Put the PTO in gear and turn the output shaft back and forth to read the indicator.

 

[JCKnife]

Totally agree with Dan!
And if you don't want to pull that nicely sealed PTO inspection cover or even open the tranny's top cover... there is a little trick that always worked well for me: one can actually see both gears (reverse idler and PTO input) and how much play there is, if a (AAA) mini- or a AA-Maglite (with lens head removed) is introduced an inch or so into the oil level inspection hole, then look trough the oil drain hole while rocking engaged PTO back and forth at the output flange.

G.

I'm about to give this a shot. Visually, you're looking for "a little bit" of play? Not sloppy but not firmly against, either?

 

[m16ty]

Too much play is better than not enough. I've always just done mine by feel but you have to take into account the backlash already in the PTO itself. I can tell lots better by "feel" than I can visually observing the backlash.

It's almost impossible to set the PTO up the way described in the TM with the trans in the truck (there's not enough room for the indicator between the PTO and the frame).

 

[gringeltaube]

Basically by doing that (as in post #4) you will actually SEE one gear (PTO input) moving freely just a tiny bit, until it starts turning the other gear (rev. idler) - in both directions.

Ideally, backlash should be ±0.01" (general rule of thumb); and be asured: that is VERY visible! Also, another rule, in case of doubt: too "sloppy" is 100x better than NO (visible) play...!
If you had another gearbox or PTO at hand you could always do some testing/ measuring on the workbench, to get an idea of how 0.01" between tooth flanks looks (and feels) like.


G.