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donmoore1904

Bevel gearbox service on a 3 spd 3410?

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donmoore1904
I just got back to the tractor I bought a month ago. I had posted some questions here about my "7010", which I now believe is a 3410 (I have a 3 spd 7010, which looks almost identical, but this has a manufacturing number of 755 - there is no decal on the hood) The driveshaft has a noticeable wobble at the rear, visible around the opening for the shifter, compared with my 7010 which has none. But no noise until I let the clutch out to take off. Very noticeable loose shaft-in-bearing-like sound. Comes and goes while moving. When I stop, the noise can remain for several seconds and then go away. The Simplicity mechanic told me it is the bevel gear box. He has a used one on his property he wants to sell me, but I am inclined to agree mine is bad. I see the parts are prohibitively expensive, especially the gears and shafts. I got the tractor because I liked all the attachments, and I am willing to keep it though the stealer will take it back. I am thinking of at least removing the bevel gear box, and possibly replacing it with a used one. At least diagnose the worn parts. I stuck my hand up underneath, and I could get any side to side play on the back of the driveshaft, which I thought I might. What would be the best source of a procedure? Just dive in? The mechanic said the easier side is the one with the PTO clutch. It sounds like basically removing the pulleys on both sides, getting the left plate off (I assume completely), and sliding the bevel box a bit left to clear the short shaft, back and down. Sounds (ahem) easy. Any tips? Thanks!

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larry8200
What you are describing could simply be a loose and worn coupler on the front of thw BGB. I'd take the driveshaft out (has to anyway) and then check the coupling & BGB

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PhanDad
Larry has an excellent point, check the fiberglass coupler for loose bolts and if a bolt is loose, there might be damage to the disk itself. If you find loose coupler bolts, check the 4 frame to BGB bolts, they're known to work loose with time. Also check the front drive shaft coupler bolts. However, I betting on a bad input shaft bearing on the BGB. I've seen a number of them. Many times the case and input shaft are worn such that neither is usable. I thinking you'll need a replacement box. See this post about removing the box: http://www.simpletractors.com/club2/topic.asp?TOPIC_ID=112066 And before you "dive in" take lots of pics for reference for reassembly, pics work great along with the exploded parts diagrams.

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donmoore1904
I agree, I thought Larry had a great point, and here is what I found (someone hopefully can help make sense of it): The bolts/connections and coupler all were solid. I removed the coupler with the set screw, and it came off slowly with prying (no noticeable wear in the keyway/radius). The input shaft to the BGB has about 3/16" lash at 1-1/2", which works out to 7+ degrees. The side to side play is hard to judge, but it is visibly noticeable, and my guess is about .015"+/- Thoughts? Other ways to diagnose prior to considering removal? I will go look at the link the last poster posted. Thanks for the suggestions guys.

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donmoore1904
quote:
Originally posted by PhanDad
However, I betting on a bad input shaft bearing on the BGB. I've seen a number of them. Many times the case and input shaft are worn such that neither is usable. I thinking you'll need a replacement box.
Bill - this was something I was wondering about, but never having been inside I could not know. The case itself can wear? Is this because the bearing is being abused so badly its outer race starts to wear on the casing holding it?

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PhanDad
Don, The input shaft bearing is a needle bearing and IMO, is the weak part of the BGB. When the bearing fails and the needles "go away" there isn't much metal in the outer race to prevent the shaft from rubbing the case. (I'm not sure I'd even say there's an outer race in a needle bearing, more like sheet metal holding the needles in place so the shaft can be inserted.) The case and input shaft chew away and there's no surface left to mount a new bearing in. And both gears are shot of course. So the only part left that's usable is the cross shaft. I'm guessing this is your problem. Only way to know for sure how is to open it up. You're aware of the pricey internal parts, so usually a used box is the way to go. I've always opened the used box, checked the gears and installed new bearing and seals unless you're sure they're good. To me, the investment in new bearings and seals is small compared to the work to get the BGB back out to install them later.

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donmoore1904
OK Phil - What you are saying is the input shaft and bearing are likely one of the first things to go, and often take the case with them. Interesting that Simplicity stocks and has all the internal parts but didn't mention the case. Any opinion on the gear lash and play I found? Is this definitely a candidate for service? I was thinking I could pull the drive shaft out of my 7010 to compare, as it is dead quiet and works fine. The shaft play seems fairly minimal - any chance I am early enough to salvage the case? I know - taking it out will tell the tale. If anyone has opinions of which side plate of a 3410 to remove, I'd be interested. I noticed in the recent threads for larger machines, people generally seem to suggest the right plate. Figures - the Simplicity guy thought the left was best.

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larry8200
If I grab the main drive pulley on the right side of the BGB in my 3416H, there is no lateral play in the bearings, just enough side to side play so you can notice it, and 5-10 degree's lash. It has been like that forever more or less. (Dad bought it new and I've always done all the maintenance) I know this is no help with the input shaft. I've never taken the back apart on one of these, but the drive pulley can be a **** to get off, whereas the PTO usually comes right off. Good Luck.

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donmoore1904
quote:
Originally posted by larry8200
If I grab the main drive pulley on the right side of the BGB in my 3416H, there is no lateral play in the bearings, just enough side to side play so you can notice it, and 5-10 degree's lash. It has been like that forever more or less.
This would seem to possibly indicate my gears aren't shot, based on lash alone. The play I described in my shaft is what I might call side to side on one day and lateral on another - looking at the end of the shaft, that .015" movement is along the diameter of the shaft. Thanks for the reply.

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donmoore1904
I checked my good 7010 at the drive pulley - about 1/8" movement at 2", or half what I have on the 3410. Also, the drive shaft has no noticeable vibration on the 7010. I didn't take the deck off to go underneath, but it seems I wouldn't find any noticeable play in the input shaft. Guess it is time to take the BGB out. Thanks again for the advice. I'll post back with what I find. How exciting, another job.

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larry8200
quote:
Originally posted by donmoore1904
quote:
Originally posted by larry8200
If I grab the main drive pulley on the right side of the BGB in my 3416H, there is no lateral play in the bearings, just enough side to side play so you can notice it, and 5-10 degree's lash. It has been like that forever more or less.
This would seem to possibly indicate my gears aren't shot, based on lash alone. The play I described in my shaft is what I might call side to side on one day and lateral on another - looking at the end of the shaft, that .015" movement is along the diameter of the shaft. Thanks for the reply.
Yup... The "lateral" play, no movement of pulley up and down. (shouldn't be) the side to side is pulling the shaft back and forth, just a tiny bit (maybe .005-.010). The lash: outside of pulley moves circulurly (is that a word?) maybe 3/8". These are my values, not specs. Be watching to see how you make out. Sooner or later I'm probably going to have to tear down the rear end either for the BGB or the vickers hydro.

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donmoore1904
quote:
Yup... The "lateral" play, no movement of pulley up and down. (shouldn't be) the side to side is pulling the shaft back and forth, just a tiny bit (maybe .005-.010). The lash: outside of pulley moves circulurly (is that a word?) maybe 3/8". These are my values, not specs.
Larry - your lash is a lot more than that on my good tractor, and about what I have on the unit under investigation. This is interesting as you say it always has been about the same, and I assume your tractor works fine. By the way, it looks *fabulous*. I don't understand where you got the .005-.010. When you say "pulling the shaft back and forth" do you mean in and out (towards and away from the BGB case)? Or perpendicular to that (towards the front and rear of the tractor)? Thanks, Don

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larry8200
on the .005-.010, if I grab the main drive pulley, and pull it away from the bgb and push it back there is just enough play to notice it. There is no perceptable play in the bearings when you lift up push left, right etc. There is no play at all in the input shaft Glad you like my tractor. My Dad bought it new, and I was the fist to mow with it in 75. It has given faithful 4-season service now for 35 years. Keeping it up has become a bit of an obsession. Here's a few pictures from Noveember 2008:




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donmoore1904
Here is an update on pulling my BGB: I pulled the left plate off, and the BGB came out pretty easily (( I noted the steps in a reply to Shoeman about his 2010) The pulleys/keys were fine. With the back off the BGB, the gear teeth looked fine. Recall outside the BGB I had 7 degrees of lash from input to output. The gear lash itself appears to be maybe 1-2 degrees. Here is the first visible problem: the input shaft can be rotated 5-6 degrees without its bevel gear moving. Obviously the input gear keyway, key, and shaft are suspect. How do I go about getting the output shaft out? With the drive pulley key removed, and the spacer behind it, I can push the shaft inward a half inch. This exposes the output shaft bevel gear key. There is a split wire retaining ring just inboard of the bevel gear. This is about a 340 degree piece of steel. I have never worked with one of these. Do I just spring it up onto the shaft diameter, and remove the bevel key and push the shaft out, letting the gear and ring eventiually fall off? You can't spring this retaining ring all the way off the shaft, can you? It seems that would deform it. Thanks! By the way, I had to wipe the drool off my face Larry. Nice ride.

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PhanDad
You have it correct. You remove the bevel gear key and, per the repair manual, "disengage the retaining ring from its groove and slide it over near the gear" . After deburring the key and groove areas ("reduce all protrusions to shaft surface level, but do not remove any surface material"), "pull the shaft out of the housing with one hand while holding the gear in the other hand". There is no mention of the ring in the repair manual, but it also comes off inside the case. The retaining ring tightens against the bevel gear when the drive pulley is tightened on the shaft with the shaft nut. The gear, the inner bearing race and the spacer are in a tension column on the shaft. The outer bearing race is held against the inner case face by the shaft seal, shim pack, and right side plate. This combination sets the cross shaft gear in relation to the input gear.

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donmoore1904
Good grief Bill, I actually figured something out. I really appreciate the reply. I had considered that when I remove the key, I will bugger the area a bit. I had a bit of trouble removing the other keys, I hope the bevel gear key is a little easier. So this kind of retaining ring is slipped over the shaft until is seats in the groove. The outboard one on the PTO side had been completely abused through earlier servicing, and really wasn't doing anything. What you say makes sense, in that the gear relationship is obviously important. The interesting part is that before removing the drive pulley key, the key, outboard spacer, bevel gear and retaining ring held the shaft in place laterally. The spacer was resting right up against the key. Only by removing the key was the spacer able to come off, which of course allows the shaft to move inward. Thanks again - I'm going back in. I am hoping the problems are limited to the input shaft. On another note, the side plates were bathed in dirt/oil, and I think at least the drive pulley side was leaking oil. This may have led to failure.

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larry8200
Just a irrelavant thought, you said: "I had posted some questions here about my "7010", which I now believe is a 3410..." A 70XX has headlights in the grill, A 34XX has either no headlights or has them mounted on the sides. Easy way to tell them apart.

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donmoore1904
quote:
Originally posted by RayS
The Simplicity System 70XX series had headlights on the sides or not at all either. http://simpletractors.com/simplicity/new_in_1975.htm
I don't believe everyone doesn't know what happened 35 years ago! Right - I have been thinking about those side-mounted lights for the 7010, but have been toiling in virtual darkness lo these many years whilst plowing. The 3410 came with some after-after market push button lights mounted to a u-channel. A real Rube Goldberg, which has been removed and trashed. An UPDATE. I visited Simplicity today with all my parts. The consensus was there was significant bearing degradation on the input shaft bearings, especially the ball bearing. The key was quite worn on both sides, causing most the rotational movement. The shaft itself has a slight amount of wear in the bevel gear keyway, matched in the gear keyway. A new key can just be pushed into the shaft by hand, and is slightly looser in the gear than a brand new gear. The needle bearing is still tight in the housing, which leads me to believe it hasn't worn the housing. The ball bearing can't be slipped into the housing by hand, which gives the same impression. What we decided was replace all the bearings, seals, keys. I think the bearings ran dry, and the bearings going south caused the key/keyways to wear. That is my opinion. The shaft was quite dark at the ball bearing, and the inner race could be shifted slightly perpendicular to the shaft (play). A new bearing placed on the shaft appears tight. There was no noticeable wear on the shaft. Thanks for the input guys. If I had to pay more than the $90 for the parts I did replace, this tractor may have been parted out. It just doesn't seem worth it. I saw a 3410 on Ebay in "good condition", with deck, rebuilt carb, etc, for $250 with no bids after 5 days... No respect.

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