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thedaddycat

BGB offset in frame?

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thedaddycat
I did the dry fit of the side plates today and noticed an offset that I had hoped was only an illusion. When I made the first set of plates I had noticed that the left side had a plate to frame gap while the right did not. At the time I attributed it to having bent the plates differently on either side trying to get the best fit. Later on, after the plates were removed I thought it looked like the BGB was not centered "right to left" in the frame. The bolt holes in the cross brace left some room to work for positioning, with but not much. When I fit both sets of plates up there was about 1/4" difference between right side and left, as can be seen. I have thought about how to remedy this and have several options. 1) Put the left support plate inboard of the original plate. Easy fix but the holes for things like the clutch and brake shaft are not super tight since I hand filed the holes out at a taper to make sure I had clearance. I had always intended this plate to go outboard. 2) Reposition the BGB to center it. This involves more filing through both cross plates and the frame cross plate to relocate the BGB mounting holes. It is the proper fix, to my way of thinking. Lastly, could those of you out there with a 3300, 3400, 7000, or 7100 series take a quick look at the BGB and see if yours is offset in the frame. It won't be by much if at all, but it matters if I try to put together a DIY article on this one....

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HubbardRA
I ran out with a flashlight and took a quick look at my AC716. It appears to be offset about a quarter inch to the left as you set on the seat. Your offset should not be a problem. I have run tractors with nearly an inch offset when I changed engines. The flex plates should handle what you have. Rod H.

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thedaddycat
Rod, The reason I'm looking at centering the BGB is not because of concerns about the flex plate in the driveline. It is to get the support plates to distribute the force evenly to the frame. The other options I had thought of were: 3) Just use the support plate in place of the tranny plate. See 1) above. Also, the point of using two sets of plates is to make it stronger. 4) Cut off the front of the support plate and butt weld it to the left tranny plate. Weld bar stock over the butt joint for strength. This eliminlate the offset but again, I don't think it would be as strong as having two sets of plates. I would like to be able to have this become a DIY for those needing BGB support for heavy work. I'm trying to have it be unobtrusive and with minimal modification to the tractor. If most or all these LFGT's have offset BGB's I'll have to take that into account.

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HubbardRA
Kirk, I have watching your development of the modification. When you bolt or weld the new plates to the existing frame, you will prpbably have a set-up that is nearly 5 times as strong as the original. I haven't done the calculations, since I don't have the dimensions, but since I do have an engineering degree, I can say that it will be massively strong compared to the original. The cast iron of the BGB is fragile, but the welded or bolted steel will stretch long before it breaks. If it breaks it will be near a weld. I have built two pulling tractors with motorcycle engines from scratch, and the frames on them were like toys compared to your design. If you make the frame one piece by bolting or welding the plates, this will remove all the chassis load from the BGB. That way it will only have to survive the torque transfer from the engine. In fact, if were me, I would want to isolate the BGB from the chassis loads. That is what broke the other one. Rod H.

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thedaddycat
You get the picture!!! If some is good and more is better then too much should just about do it!!!! This is a loader sub frame cross bar installed in both sets of plates. I have a crude drawing of it, good enough to make one from.

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