Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

rfsmith1952

BGB replacement

Recommended Posts

rfsmith1952

I'm about to disassemble my T-12 (Christine, again) for what I think is a BGB issue. I've done it once, but I thought that this time, I'd ask for advice ahead of time. :D General procedures step by step would be appreciated. Should I take off the forward/reverse control arm at the vickers end? Same question for the pedal linkage. Will the BGB itself will slideout, or must you remove the shaft first?

Thanks

Bob

PS I do have the large frame tractor repair manual, didn't see breaking it in half in there.

Share this post


Link to post
Share on other sites
RayS

You would need to remove the linkages so that you can split the tractor in half. Then remove at least one side plate so that the BGB can be removed. I usually remove the right side plate so that I can get the shims flush with BGB case when reinstalling.

Share this post


Link to post
Share on other sites
rfsmith1952

Okay, got the tractor broke in half. Had trouble with the right side plate. There are TWO retaining clips on whatever that shaft is near the bottom and back of the tractor. The clips are both on the right side, on either side of the side plate. You must take them out, push the shaft out from the left side first, then pull it back out of the right side. Then the side plate comes out.

I removed the cover. Inside the BGB looks fine. Gears are sharp, no metal pieces, and it started to turn and work correctly after I got it out. But I did find a woodruff key in there. So I believe that is the problem.

I will take some photos tomorrow.

Now, I have another BGB that I believe is in good shape. So the question is repair or replace? Replace would just be a swap out. Repair would be the keys, seals, bearings, retaining clips etc.

My initial inclination is to just swap out and then repair the original one at my convenience. Then I know I would have a good one on the shelf. Your thoughts?

Thanks,

Bob

PS it was much easier to disassemble this time. I'm going to try and find the photos from the first time and post them with a sot from this action and compare them.

Share this post


Link to post
Share on other sites
fishnwiz

At this point, unless the spare BGB has been rebuilt, I would go ahead and redo the original BGB. Not sure what the cost is for everything but at least you have a known rebuilt BGB. I can,t imagine the total for parts is too much money and as long as the bgb is out and apart and you are talking about redoing the bgb anyways I would not take a chance on the other bgb.

At the very least if you do go with the spare BGB I would open the spare up and check out everything before you assume it's good and install an unknown BGB.

At the very least, you can now split a tractor in half in no time at all.

Best of luck on your project.

Share this post


Link to post
Share on other sites
RayS

If the woodruff key fell out the gear is spinning on the shaft. The shaft would have had to move far enough left or right for it to fall out. I would make sure that the shaft is ok before reinstalling it and if you can pull the key out of the shaft by hand when trying to reinstall it the shaft is worn out and more than likely the gear as well in the key way.

All new parts in a gear box are over $400 new from dealer but last 30 years.

Share this post


Link to post
Share on other sites
fishnwiz
:o Wow, I am shocked at the 400 dollar number! I guess I would be installing the spare BGB! I had NO idea on parts cost. I pay less then that for complete tractors!

Share this post


Link to post
Share on other sites
rfsmith1952

I think I found the issue. There is no retaining ring on the horizontal shaft. There also appears to be some heat damage on the shaft, near where the ring should be. Last photo is the garage. Much better organized this time. Was an absolute mess last time.

BGB01.jpg

BGB02.jpg

BGBretainer.jpg

BGB03.jpg

So my guess is the retainer was never installed, or it disintegrated, causing the shaft to move laterally, causing the key to fallout, causing the BGB to stop working, causing Christine another vacation. :D

BGB01.jpg.d79098c0fc5d72d8693ae1cc2a9d6bc4.jpg

BGB02.jpg.9a5ca2e313de3597532e27bcd6acba44.jpg

BGBretainer.jpg.bd7b9746e78f013a56a6716c328d7d87.jpg

BGB03.jpg.2b5dd4cb210b049f5ea100acd59de98f.jpg

Share this post


Link to post
Share on other sites
RayS

I do not think that ever had a retaining ring. The FDT`s didn`t have them. They rest against a stop cut into the shaft. Your picture showing a retaining ring is from a 7100 series. The side plate in that diagram is from a 7100 series. Yours has the stop cut into the shaft. Check to see if the key fits the shaft. If it falls out or you can remove it by hand that is the problem.

If you need a Homelite manual let me know. I have all of them.

Share this post


Link to post
Share on other sites
RayS

The gears look good. The land that the bearing rides against looks burnt (blue). which means you would get lateral movement (side to side play) and if it gets big enough the key may have fallen out. The factory doesn`t publish tolerances but if that land wears, the gear slides back in forth until it self destructs. Just my 20 years of machining back ground talking. The key will get cocked working back and forth until it pops out.

Share this post


Link to post
Share on other sites
rfsmith1952

Got the other BGB out, which was actually the original one that came with the tractor. This one has a retaining ring holding it. Looks good to me. Pulley fits, collar fits. Left side shaft is longer than the one that was in, but I don't use that for anything anyway. Deck is driven from the front PTO. Gears both look good. My inclination is to install it, then deal with defective one later on.

BGBNew01.jpg

BGBNew02.jpg

BGBNew03.jpg

BGBNew01.jpg.062376678e750359f29bfc4c9c017945.jpg

BGBNew02.jpg.56043d32ffea815279782c461e1d06a0.jpg

BGBNew03.jpg.6c8203080b69752ab05d8761cbe3f152.jpg

Share this post


Link to post
Share on other sites
PhanDad

I'm a little late on this post, but Greg (GLPointon) documented a BGB rebuild. It's in the Tech Tips Section:

https://simpletractors.com/forums/topic/46509-bevel-gear-box-rebuild/

An original Allis built Homelite T-12 BGB has the retaining ring, not the "step" in the shaft (Ray called it a "stop", the shaft is larger in diameter). From the pic, it does look like a step vs a groove for the retaining ring.

The retaining ring (or step) stops the shaft from moving to the right (when sitting on the tractor). IMO, for the key to fall out, the shaft has to move to the left. The movement to the left is limited by the external spacer/pulley setup on the right hand pulley (see reference post below). If the pulley isn't kept tight, the shaft can move left; maybe until the key falls out before the pulley falls off. Also, there are different cross shafts on the BGBs depending mainly on the tractor drive (gear, hydro, shuttle). The spacers used in each of these applications are different. If someone swaps out BGBs and doesn't use the matching spacer, then the shaft can also move to the left.

A post discussing the spacer and my babble about cross shaft movement:

https://simpletractors.com/forums/topic/34485-bevel-gear-box-play/

Another rebuild thread with the wrong cross shaft for the hydro trans:

https://simpletractors.com/forums/topic/49712-bgb-rebuild-update-with-pics-11-13-13/

Happy reading.

Edited by PhanDad
Fixed Links

Share this post


Link to post
Share on other sites
RayS

It may have a retaining ring and groove Bill in the original build of the tractor. His first picture shows a land, step or stop. Call it what you like. After 20 years of machining for wheel hubs for the big truck industry. I have heard it referred to more than that on blue prints. First picture is clearly one of the three.

Share this post


Link to post
Share on other sites
PhanDad

Ray, not being a machinist, at first I didn't understand what you meant by a stop; I thought of a rectangular shaped "key" stuck in the shaft that would fit inside the machined part of the gear. How dumb is that? After looking at the pic for awhile I figured out the shaft had different a diameter. Just trying to help others understand how it functions.

Any idea of the actual diameters? I'm guessing a 1/16" step so the FDT box has 3/4" dia gears? While the PTO end would be 7/8"? This would mean the spacers at the tranny drive end are not only different in length, but inside diameter as well?

A lot to keep straight when swapping assemblies/parts.

PS - Another word you used is "land", that one was easier to figure out - the flat end of the gear that mates to the inner bearing race. ;)

Share this post


Link to post
Share on other sites
RayS

I know. If the place I worked at didn`t go out of business. I would have attempted to get those degree carrying engineers to come up with a single word everyone could agree on in that place.;)

Flat end of the gear that can`t go no further against the stop, step or land.:D

Either way. I was just attempting to help as well. That is just what they have been called on blue prints that I have worked with at one plant that I worked at.

Share this post


Link to post
Share on other sites
rfsmith1952

Thanks both. I knew what Ray meant, and I know what you (Bill) means, and I believe Bill is right about what happened. I believe the pulley nut was never tightened as much as it should have been, because the spacer wasn't seated properly, inside the hole of the sideplate, up against the shims. It was outside the sideplate. This caused the shaft to move left (if you sit in the tractor seat). I had a good look at it since it's been out (it's still out) and now I understand better what is what. I might take some more pix if you think the club would benefit. Anyway, thanks again, you guys make me fearless! :D

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


  • Who's Online (See full list)

    • RickS
    • dayardguy
    • Brettw
  • Today's Birthdays

    1. Big 10
      Big 10
      (71 years old)
    2. cowfan
      cowfan
      (51 years old)
    3. dynodave
      dynodave
      (71 years old)
    4. WaylandLegacy
      WaylandLegacy
      (44 years old)
  • Recent Status Updates

    • SonOfCreepfeed

      SonOfCreepfeed

      Thinkin' about this old girl.

      · 2 replies
    • Dean McFadden

      Dean McFadden

      Good morning peeps! I’m always searching for helpful information with my AC collection. Hope to find out new information and pass on my own experience in restoration. Here are some pics of my babies. I’m still looking for front rims for the 410 so yesterday I put the 310 wheels on took it for a drive. Working pretty good but still needs some carb work. Gotta get the 310 running next. Have a great day!😁
       

      · 1 reply
  • Adverts

×