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Old 08-17-2009, 01:59 PM   post #16 of 22
LoveLearn
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Default Re: Slipping Snapper

"If I turn the wheel close to the differential the opposite one turns the other
way round."

"If I start the motor with tires removed one sees that the axles slightly
turn but can be stopped easily by hand."

The ONLY link in that drive train which should be capable of soft-slipping is contact between the rubber power-collection driven disk and the motor-attached driving aluminum disk. If you can verify that you are observing soft slippage somewhere else in your drive system, that slipping link must be identified and locked back together.

Chains may jump off their sprockets, but they don't soft slip as you've described. Splined shafts don't soft slip inside steel driven rotating parts unless that section of splines has broken off from either the driving shaft or the driven part. I have a Kubota B5100D tractor with spline-shaft driven front Power Take Off shaft which slips inside the broken spline area of its cast iron driven shaft. Failures like that are EXTREMELY uncommon, so it's unlikely that you're experiencing one of those failures. Kubota was not stupid enough to select cast iron when fabricating that driven shaft, but the American subcontractor which made them so those excellent little tractors could drive belly mowers to US market buyers did make that stupid materials selection. Kubota failed to spot the error, sold mowers with those failure-prone cast iron splined shafts and never stood up and replaced every one of them as they should have done. Even that premium-priced brand sold at least that one junk-quality part and failed to issue an honest parts recall & replacement program despite the fact that they have long known those internal splines are too brittle and fragile like "glass gears."

When you get to the bottom of this little mystery, please take some close-up photos and share them with others here so we can better understand future failure issues.

Soft slipping you described still sounds like a clutch - rubber disk interface surface problem to me rather than something within the transmission cases which should be filled with grease to their level-check holes.

Walt, we need your experience-based feedback about the following potential issue. Can low transmission-case grease levels cause high friction between the internal splined shaft and the sliding input gear's splined surfaces? Frequent Snapper owner complaints about difficulty in getting the rubber disk to slide over to the reverse-spinning side on the driving disk must either be caused by external linkage or by internal transmission friction along that splined shaft. I expect some of these difficult-to-shift transmissions haven't had their transmission grease levels checked for 10, 20, 30 or more years, yet still transmit power to their driven axles! If they are running without enough grease splashing around inside to keep those splined-sliding interface surfaces wet with lubrication, wouldn't that explain why they stick & jerk while resisting shifting-linkage load rather than sliding freely all the way from full reverse position through to full-speed forward and back? Being durable transmissions, many owners probably don't check their transmission grease levels for decades. They can usually get by failing to check grease levels in rear-wheel drive automobile differentials because most RWD rear ends don't seep enough lubricant through their seals to wet their outside case surfaces. But most Snapper transmissions that haven't been recently cleaned are covered with grease film which makes them behave like wet air filters so they form increasingly-thick grease and dirt wetted surfaces. The grease wets the dirt so the attached layer keeps getting thicker as the transmission becomes less filled. I assume Snapper transmission grease is typically slowly seeping out based on these observations. Does this analysis make sense to you? Do you think low grease levels may explain many ratio-shifting difficulties?
John
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Old 08-20-2009, 09:54 AM   post #17 of 22
Don B.
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Default Re: Slipping Snapper

I am going to look at a '79 model 11 HP Briggs powered Snapper RER later today. I guess it stopped pulling all at once,.No word on slippage up to that point or anything. I have not had to lwork on a Snapper in years what is most likely problem (I'm trying to figure out if its worth what the guys asking; I dont wanna buy it if its gonna cost me that much to repair) Drive disc or belt problem probably OK; if its likely internal I will pass.

Sorry for the thread jack but it appears that the solution here may also be the solution on this mower that I am looking at so they are kinda "related".
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Old 08-20-2009, 12:14 PM   post #18 of 22
Walt 2002
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Default Re: Slipping Snapper

Well I did not pull up the drawing you are talking about BUT - the rubber tired driven wheel runs a sprocket inside the center chain case which, of course, runs a chain that turns another sprocket mounted on a hub which is hex shaped inside. This sprocket and hub turns and rides, slides, back and forth on a long hex shaped hollow tube as the gear (speed) selector lever is moved. Sitting on the seat, the right hand end of this hex tube has a sprocket on it, inside the gear case which is mounted inside the right hand axle support plate. This small sprocket runs a chain up to a large sprocket/small gear duplex. This small gear runs a large, "bull" gear on the differential assembly. The long axle coming from the left side of the mower runs into this differential assembly thru the inside of the hollow hex tube and the end actually runs in a bushing inside the short right hand axle. A gear is welded 6" or so from the end of this long axle and the power is transmitted thru the bull gear, the sun gears of the differential to the gear on the end of both axles.

That is how all Snapper RERs work, I am lost as to what you say is working. I probably suggested way back that you check the tapered bolt running thru each rear wheel hub and thru each axle.

Walt Conner
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Old 08-20-2009, 12:19 PM   post #19 of 22
Walt 2002
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Default Re: Slipping Snapper

Quote:
Originally Posted by Don B. View Post
I am going to look at a '79 model 11 HP Briggs powered Snapper RER later today. I guess it stopped pulling all at once,.No word on slippage up to that point or anything. I have not had to lwork on a Snapper in years what is most likely problem (I'm trying to figure out if its worth what the guys asking; I dont wanna buy it if its gonna cost me that much to repair) Drive disc or belt problem probably OK; if its likely internal I will pass.

Sorry for the thread jack but it appears that the solution here may also be the solution on this mower that I am looking at so they are kinda "related".
Don B. Somewhere back along the line I probably recommended a test to see if that tapered bolt thru one of the hubs/axle was sheared, a common occurrence.

Walt Conner
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Old 11-15-2009, 03:03 PM   post #20 of 22
adams77331
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Default Re: Slipping Snapper

I too have a slippage problem. I recently replaced the clutch disc and drive disc. My problem appears to be an adjustment issue. I have a rear drive 28-inch Hi-Vac. When standing the mower on it's back, clutch is engaged, in 1st gear, and grabbing both tires and rotating the direction they would be going forward, the transmission spins without much effort (transmission is not firmly engaging the wheels), when in 5th gear I cannot easily turn the tires (transmission has firmly engaged the wheels). I want to make it clear that in neither case is the clutch disc spinning against the drive disc. There is firm engagement there. Subsequently when in low gear I have almost no forward motion, especially up an incline, and it moves fairly well in high gear. Please help.
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Old 11-28-2009, 01:31 PM   post #21 of 22
adams77331
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Default Re: Slipping Snapper

I have found that I am missing my brake return spring. Maybe that will solve my problem.
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Old 11-28-2009, 08:33 PM   post #22 of 22
dc 3mech
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Default Re: Slipping Snapper

Let's look at the slippage problem ,which seems to be the most common drive problem,from a different angle.The chain case holds the driven wheel and the driven wheel is pressed against the drive disc by a spring.The chain case is free to pivot around the axles,limited by the driven disc against the drive disc,the shift yoke and the bushing which rotates in the yoke. The chain case is allowed to slide side to side by the shift lever through the shift rods and bell crank and the bracket holding it.When all this is tight and adjusted to the proper place everything works as designed.If you need to drop the drive disc below the lowest position specified then you should check for wear in the axle bearings,this allows the chain case to move away from the drive disc,and at an angle which can effect one gear more than another.My 28 in.rer appears to have ran onto something which bent the distance rod up,this allowed the left fender to move inboard at the bottom allowing the bearing to loosen and rotate.this mower has the bronze bushing type bearing which is lubed with a zerk.I'm told these will wear out to the fender and then some. this probably causes lots of the problems noted
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