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deebig

BGB free play

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deebig

Just curios of what the amount of free play is acceptable. Using the outer circumference of the variable speed pulley for reference I get 3/4" travel when I rock it back and forth.

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Alltractoredup

3/4" sounds like a lot, but I am not sure what OEM tolerances are.  I would say that it is wearing out and may need a rebuild in the near future.

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PhanDad

I've never seen an "official" Simplicity description of "excessive" BGB backlash.  

The most definitive comments that I can remember posted on this site were by @RayS; his comments:

I have rebuilt with all new bearings and shafts and backlash on the gears is 1/16" to 3/32" with all new parts.

The 1/16" to 3/32" is rotational at the cone clutch that I am talking about.

At the outer diameter of the cone clutch.

His opinion of a measurement of 1/8":

I wouldn`t mess with it. That is only .032 difference. My numbers were on all brand new parts. Not used parts and there is nothing written in the repair manual on what I came up with. Simply what I have observed in the ones that I have rebuilt with all new parts.

If you had a 1/2". Then there would be an issue somewhere.

Above from this post:

https://simpletractors.com/forums/topic/48017-is-there-acceptable-side-play-on-bgb-shafts/

 

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PhanDad

 

This is too much:

 

What I found:

Many times the cause of lash is a worn key if you're lucky:

IMG_9450.thumb.JPG.2fe2a1be3d24008331ff4483343a71da.JPG

And probably if the key is in that bad of shape, you're a little lucky if you find just shaft damage:

IMG_9451.thumb.JPG.54ad2175087c08b3e591b0b17c13d09f.JPG

IMG_9452.thumb.JPG.40f67bc241e5129b335e6bf7d6957364.JPG

Unlucky is gear keyway damage:

IMG_9447.thumb.JPG.71944668a2e3b67ca8d944458a86d8da.JPG

If just the key way is damaged, you can have a keyway cut 180 deg and salvage the shaft.  If it's worn as was the case with the pictured shaft, you'll need a new shaft.  And if the gear keyway is damaged, a new gear too.

The BGB that the above parts ran quiet but was leaking fluid from the tranny drive pulley side.  

Hopefully you'll be lucky when you investigate.  

 

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deebig
4 hours ago, Gary said:

I'd agree with the 1/32 - 1/16, maybe even up to 1/8" backlash.  Any more than that, and there's probably damage to a gear/shaft/key, et all.

where are you measuring the backlash? I am measuring 5/8ths on outside edge of 5 " pulley

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wwbragg
On ‎2‎/‎8‎/‎2019 at 12:44 PM, deebig said:

5/8ths on outside edge of 5 " pulley

This equates to 1/8" at 1" from the shaft's center.  I agree with @deebig in that 1/32 to 1/16 would be better.  In other words 5/32 to 5/16 at the 5" edge.  1/16" is .0625 or 60 thousanths - - -that is a lot of gear lash.

Edited by wwbragg
spelling

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wwbragg

Wait a minute - - I might be confused - - - maybe not???  :S 1/16" lash 1" from the center is 60 thousandths.  1/16" on a 5 " center is only 12 thousands (on a 1" center) which is a reasonable amount of play.

Edited by wwbragg
spelling

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TimJr

Backlash isn't the only thing to judge.  There should be basically no end play on the cross shaft.  I don't know if there is a Simplicity spec for end play on the cross shaft, but it should not be enough to really see.  Obviously it can't be set up too tight, otherwise there will be gear problems, but I was always taught that it needs to spin freely, but have minimal end play.   The input shaft shouldn't wobble - the needle bearing on input shafts is a notorious wear point.  As for your backlash, how does it feel?  This is difficult to explain, but often times when the problem is a worn out key/key way, there will be a small amount of normal very free backlash, but then you can keep turning the shaft more when a little effort is put into turning things.  Again, hard to explain, easy to feel once you have some experience.  Make sure it isn't just a shot pulley or key outboard of the gearbox that you are feeling.  

Edited by TimJr
typo
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Chris727

@TimJr is spot on. Those variable speed pulleys have play in the pins, even when dealing with nearly new parts. Check at the inner half of the pulley instead. These units will operate still with quite a bit of wear. On my first B-110, the pulley can be rotated probably an inch or more and its still going but the likelihood of being able to re-use any of the parts will decrease. 

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