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Ac-310 Bevel Gear Box Interchange?


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#1 oldiron OFFLINE  

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Posted December 20, 2013 - 10:48 PM

I have the chance to go pick up a free 1971 310 with a bad BGB this week, its a super clean but well used machine owned by a buddy's dad. It runs and drives fine but I had checked the BGB last year when I was there and it had about 1/4 turn of play in it. It makes no noise and the shafts feel tight but there's a ton of backlash.

Its done nothing but mow grass since new.

 

 

I'm heading that way for the holidays this year so pretty much either way the 310 will be heading back with me. What it needs will determine whether its a keeper or parts machine I guess. The best part is that he replaced the motor several years back with a rebuilt K341 16hp which still runs like new.

 

Either way, the price is right.

 

I've got a few good used gear boxes here, will any of these fit a 310 with variable speed gears?

 

I've got one from a 3415H, one from a 410 3 speed, and one from a 7016 3 speed. I may still have one from an older 3112 too but I've yet to put my hands on it. It may have gotten used or traded off.

 



#2 boyscout862 OFFLINE  

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Posted December 20, 2013 - 11:30 PM

Just rebuild the BGB. You can download the manual from above. Good Luck, Rick



#3 oldiron OFFLINE  

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Posted December 21, 2013 - 05:46 PM

It won't cost anything if I can just swap in another one, I'd be looking at $150+ to rebuild it. My guess is it'll need at least one shaft and gears, plus seals and any bearings. I'd expect to find the key ways all wallowed out with how much freeplay its got. The bearings didn't feel loose.



#4 sammiefish OFFLINE  

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Posted December 21, 2013 - 11:01 PM

it is my understanding that the hydro bgb would not work with a variable drive system.

i dont think the shaft is long enough.  there were also shaft thickness variations as well.

if you were to abandon the variable on the 310

then I think any should work fine with just pulleys on the bgb and rear end

Im sure someone can give you a more definate answer... but generally

I think your issue will be weather you can maintain compatibility with the variable pulleys.


Edited by sammiefish, December 21, 2013 - 11:03 PM.


#5 oldiron OFFLINE  

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Posted December 22, 2013 - 10:42 PM

I'd toss the variable setup in heartbeat if thats all that it would take but I'd need a set of pulleys to replace it all with.

I think shaft diameter is fine on all the newer running board tractors from what I've been reading.

 

The one BGB came from a 6 speed that was all jammed up, I got tired of taking the 6 spd shafts apart to clean off rust and dirt.

I've owned at least 25 older simplicity and AC large frames over the years and have only had one three speed. All I ever find is hydrostatic or shuttle drive machines.  I wish they all were 3 speeds.

I have to say that this is the first bad BGB I've run across.



#6 sammiefish OFFLINE  

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Posted December 23, 2013 - 10:41 AM

The  following is some text that I found somewhat useful in understanding the different applications of BGB's.  I had it saved as text on my computer... maybe you can glean some wisdom from it as well... sorry I dont have authors names or Id give them credit.

So, here is the text... (not of my authorship) I hope you find it useful :

 

The 3012V should have the same gearbox as all of the long wheelbase varidrive FDTs. Not sure if Hydro models use a different cross shaft. The short wheelbase use a different cross shaft. So there are at least two FDT gearboxes. Then the RBT's have a variety as well. Not sure how different 6 speeds are from hydros. I think the AC 300-400 used the same box as the 3300 or early 3400. Not sure what was in the AC-built homelites.


The gearbox could be replaced by any of the AC 400 series, Simplicity 3400, 7000, and 7100 series, but you would have to remove the cone clutch on the later models. If you want a complete BGB and rear with side plates and the correct mounting points for your seat deck, then you'll need one from another 300 with variable speed. The 400s did not have a varaiable transmission.



A hydro has a totally different transmission, even the vickers and sunstrand gearcases do not interchange with each other. The only transmission that will work in a "variable" is another "variable." A regular 3 speed has too short of an input shaft and the shuttle has four forward gears and a planetary for reversal. Its kind of a pain to swap transmissions and gearboxes out from between the plates and the 300 and 400 plates are unique to those series, it sounds like you want to have something on hand for a quick change out, then the quickest way is to have from the BGB back able to be immediately swapped, that way all you have to do is disconnect the belts, linkages, and the four BGB bolts and driveshaft, then roll the other rear over and mount it up.

 


Edited by sammiefish, December 23, 2013 - 10:46 AM.

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#7 oldiron OFFLINE  

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Posted December 23, 2013 - 07:42 PM

I have one 3410 with a three speed transmission, the gear box looks the same as the one in the 310, other than the pulleys. I'd have to have both side by side to compare and measure the BGB shafts. Considering all that's going on at the BGB on a 310, I'd guess it has a longer cross shaft.

I also have a 3410S that has a swapped in Vickers hydro trans. Its a combo of the hydro model rear end and shuttle front end and BGB. The linkage was modified to work as needed. I didn't do the conversion but it works fine.

I've got a 3212V rear end but the pulleys and belt arrangement is different.


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