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gear box shims?


Chris727

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Hi. I am putting the sideplate onto the BGB on a B110 and was wondering what the proper procedure is for determining the number of shims to use. I tried searching the archives for info but all I got was an error message. There are probably 7 or 8 thin shims and one thick one. This seems excessive as the shims stick out beyond the side of the BGB and when I tighten the bolts on the sideplate they cause a gap between the side of the BGB and the sideplate. It seems these are meant to set the endplay. The service manual does not give detailed information on this, all it says for reassembly is "Install in reverse of removal." I had painted the BGB and the plate (shims remained unpainted), it appeared there may not have been paint between them from factory and wonder if I need to actually remove shims now. Thanks in advance. Chris
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Hi, The seal should be pressed clear in to hold the bearing in and then the shims should be added to the outside until they are flush with the side of the case. The purpose is for the side plate to hold the seal and bearing completely in and keep the gears properly meshed. Al Eden
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I always thought that the shims are used to set the gear mesh tolerance. The seal should be pushed in only as far as the needed shims make it push in, mainly just to keep the seal straight. I'll look into the books I have and check.
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I think Al's method relies on the BGB casting to set the tolerance between the meshing gears. I would be surprised if Simplicity did that. But??? After writing the first post I looked and didn't find any related material in my manuals, but I did recall how I used to do it. I have put numerous BGB's togeather this is my method: I would start by using the original shims, even with new gears, this always got me in the ball park for thrust. I'd use the thickest shim on the outside and lightly tap on it until it was just above the BGB casting. To finsh pushing the seal in and shims flush, I would bolt the right side frame plate down. Slide the shaft and gear together and bolt the right side drive pully on using the locking nut. Lightly tap with a brass hammer the drive cross shaft from the cone clutch side. This will insure a tight fit of the right bearing and shims against the outside frame plate. After this, I would check the tolerance by feel. I think it felt like around a 20th of thrust. 0.020. I also recall checking the mesh by rotating the input shaft while holding the output shaft still. I think it rotated a little over an eigth of an inch. If it felt to tight, I would remove shims, too loose I'd add some. Sorry this isn't more technical, but it worked.
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Hi, On the newer boxes, there is a steel ring that fits inside the seal and pushes against the bearing. This subject has come up in the past and the same questions were raised, I called the factory and was advised as I have stated there is no adjustment and the bearing cup needs to be held in against the case. I know this is how they were assembled in the factory. I would advise to call factory service to verify this. If I get time, I'll look in the shop manual, I think I have seen it there also. Respectfully, Al Eden
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So, Al, if I understand right, you can shim not enough, but it really isn't possible to shim too much except you'd push the side plate outwards? After replacing my blown BGB box I brought a pocketful of parts to Pat Rarick to ask where they went: 3 shims and the sleeve that goes behind the drive pulley. You should have seen Pat's face. He is very polite. -Don
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Here's a section from the large frame tractor manual on BGB asssembly http://simplicitytechpubs.com/6767PRINT/PDF_files/TP_500_973_01_SV_SMA_Sec5.pdf
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16. Install seals at this time. When installing seal (D, Figure 5) drive seal in until it contacts the outer race of the ball bearing. The seal is what maintains the ball bearing in its correct position. Once installed, stack shim pack (A, Figure 5) so that half the thickness of the thicker shim protrudes the bevel gear case housing machined surface. This insures the shim pack will compress when the side plate is installed.


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