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pagordon

Bevel gear box play

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pagordon
I have a allis chalmers 312h and i got a used bevel gear box for it. when i got my new/used bgb the cross shaft slid back and fourth like a inch or maybe more and i was thinking that was normal because i had no experiance with any others. well i put it in and tightened the nut on the hydro drivr pulley and there is still side to side cross shaft play. id say the play is somewhere around 1/2 inch. this tractor has a electric pto so there is no pulley on the other side of the cross shaft for attachments or a clutch. So my question is what would cause this and is it fixable? I see they have shims for it but does that help with cross shaft play? i got it used and figured it has to be shimed already. Any help would be appreciated. Im a car guy and this is my first real tractor so im new to the bgb.

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sammiefish
Im sorry I dont have any first hand experience but there are a couple of articles here which may help get you started... Its my general impression that these are somewhat rebuildable http://simpletractors.com/Club2/portal_articles.asp?catid=35&cattitle=Bevel

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PhanDad
Sounds like the spacer that goes between the drive pulley and BGB is missing. It goes into the BGB oil seal and the seal lip rides on the outside of the spacer. The drive pulley is tightened against the spacer if I remember correctly.

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pagordon
The spacer is there i put that in. it just has a little back and forth play its enough you can see it. Id say a quarter inch but it works fine just dont want to have this bgb fail and have to find another one. my local dealer had no clue about shiming and could not find much about it in there shop book.

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sammiefish
btw, the end without the pulley is the end that gets the pulley to run rear attachments like a tiller, leaf vac, revitalizer, chipper shredder, sprayer.... etc... when you get it fixed maybe you wanna get the 5" pulley for it... : )

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pagordon
So is the other end supposed to have a pulley on it from factory? I just got this thing like a month ago and there was no pulley. Does anyone know what the shims do? I know this cross shaft has to much play but why? All the bearings felt good and looked good from the outside. It's got me stumped as to how to get it tight.

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PhanDad
Could be the wrong spacer. I believe there are least two different length cross shafts/spacers depending on the BGB/type of transmission. Did you use the spacer from the replacement gear box or your old gear box? Is the replacement box exactly the same? The shim story (I as best I remember): The shims on the cross shaft are on the outside of the box, between the lip seal and the side plate. They stack and take up all the space between the side plate and lip seal. They keep the lip seal flange pressed tightly against the outer race of the ball bearing which in turn ensures the bearing is seated all the way against the case. The cross shaft driven gear "floats" between the inner race of the ball bearing and the retaining ring (or step maybe?) on the cross shaft. The cross shaft can only move to the right (sitting in the seat) until the driven gear hits the center race of the bearing. However there is nothing internally to stop the cross shaft from moving to the left until the retaining ring or driven gear key hits the bolt holding the input gear on the shaft (or the far side of the case maybe?). The external spacer clamped between the ball bearing inner race and the driven pulley stops the movement to the left. I believe without the proper length spacer, the spacer won't be clamped and you'll have movement to the left. Without the shims, there can be movement to the right when ball bearing moves right until the lip seal hits the side plate. I've never seen 1/4" to 1/2" of BGB shim used, that's why I think it's a spacer issue. A BGB parts diagram or section 5 of the repair manual will make reading the above much easier. Hopefully the above is correct, and if not, another member will post a correction. I haven't had a BGB open for years and without the parts to play with, it's hard for me to figure out exactly how things work from drawings. As to the left side pulley, one didn't come with the tractor. If you bought a rear attachment (such as a tiller), the pulley came with the attachment.

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pagordon
Yeah maybe it is the wrong spacer. I thought the drive side of the bgb would be the same for all the tractors. This bgb came from a 410 shuttle and mine is a 312 hydro. I'm going to have to look around and try and find out if these two tractors used a different spacer. I only have my original spacer so that's the one I used.

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pagordon
Yeah you guys hit the nail on the head. turns out a hydro has a smaller spacer and the shuttle has what looks like a two piece spacer. Thanks for the help i appreciate it. Maybe i can just use some washers to space it out and make it tight.

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