Pointers on rebuilding a BCS tiller gearbox

   / Pointers on rebuilding a BCS tiller gearbox #1  

farmerboybill

Platinum Member
Joined
Mar 4, 2008
Messages
783
Location
Southwestern Wisconsin
Tractor
BCS 850 diesel and 735 diesel
Hey,

I just got in from working on a BCS 735 with 26 inch tiller I'm getting ready to sell and wanted to pass along some pointers -

1. I swear I haven't bought a used tiller with any oil in it. Seriously, I SWEAR IT. Don't assume the previous owner knew what he was doing. He didn't. The tines will be shot (pointy like a steak knife? They're shot), one or both seals will be bad, and the gearbox will be outta oil. If you buy a used tiller box, rebuild it right away. It'll last forever with proper care. It'll die fast with no oil.

2. You can get away with reusing the bolts when replacing the tines, but I do not recommend reusing the nuts. Frankly, I've not seen bolts worth reusing either, but maybe you'll get lucky. When replacing the bolts, use grade 8 standards or grade 10.8 metric bolts. Skip the slightly cheaper grade 5 or 8.8 bolts. I use the all-metal lock nuts, not the nylon ones. Make sure they're TIGHT. If they come loose and the tines worry them for awhile, you'll need a sawzall to cut them out, I have on one tiller. The older flat top tillers don't apply as they have a better type of tine. Those bolts are always reusable. You can still get these tines from Joel at Earth Tools, but not anywhere else.

3. DO NOT reuse the lock nuts that hold to tine assemblies to the main shaft on the gearbox. I've now seen three gearboxes that apparently had the nuts reused and come loose. Those lock nuts are very cheap vs. a new tiller box

4. At the end of every season, take the assemblies off the gearbox and clean out the space behind the seal protector. Crap gets up in there - long weeds, plastic twine, metal wire, dirt, sand, gravel, telephone poles, small furry woodland critters, you get my drift. If it's left in there, it WILL destroy the seals. An hour cleaning these out is much preferable to replacing seals and bearings.

5. When you go to replace the seals, you WILL break the bearings, even if they're in perfect shape. Don't buy the fancy throw-out bearings found in there. A $9 standard 6205 M25X52X15 will last just as long as the $50 one they recommend.

6. Pay attention to how the tines go together. You'll have an aneurysm trying to remember how they go together if you don't pay attention. The innermost tines should be timed a special way to prevent rock from lodging between them and the gearbox. It's hard to explain, but each side should be pointing the same way as they go around.

I'm sure I'll think of more. If you frequent other sites I do, you'll see this post again.
 
   / Pointers on rebuilding a BCS tiller gearbox #2  
If the bearing are still good and tight, the races should come part way out of the bore when dissembling the gearbox. If all the parts look good they can be pressed back together. Don't try to press them inside the gear box since the outer race must give in order for them to fit back together.

Seems like a 6200 series bearing isn't quite rated for the axial loads from the ring and pinion gear, but if you can get away with it, it's good to know.
 
   / Pointers on rebuilding a BCS tiller gearbox #3  
That is some useful info!
Wish I would have known about the bearing substitute. I got hammered with the $50+ for that bearing. Just curious what oil works the best in the tiller gear box?
 
   / Pointers on rebuilding a BCS tiller gearbox #4  
Old thread, but it has some good info to revive. While I was replacing the tines on my 30" tiller, I noticed it had a 'click' or slight rattle sound when I spun the tine shaft. I checked the gear box oil which was low, and after refilling it I found one of the side seals is bad. Can the coupling be pulled, and the 'tine shaft/ring gear' be pulled to replace the side seals without damaging the bearings? Do you think the bearings are bad too since I can hear them rattle slightly? I've had this tiller for 19 years, so a rebuild shouldn't surprise me. The bearing prices surprise me though. especially if I need all 4.
 
   / Pointers on rebuilding a BCS tiller gearbox
  • Thread Starter
#5  
Don't buy the BCS bearings. They have a "special" super expensive bearing that is a total waste of money. Go buy a pair of 6205s from any bearing dealer. You can't replace the seals without removing the bearings.
 
   / Pointers on rebuilding a BCS tiller gearbox #6  
Don't buy the BCS bearings. They have a "special" super expensive bearing that is a total waste of money. Go buy a pair of 6205s from any bearing dealer. You can't replace the seals without removing the bearings.
I assume they are open bearings. I've only found the sealed bearings so far locally. I'll keep looking - Thanks
 
   / Pointers on rebuilding a BCS tiller gearbox
  • Thread Starter
#7  
You can pop the little inserts out and make them open bearings, or just leave the inserts in - gear oil will still get to them. Also, odds are the front and back bearings are good, so you won't need them - just 2 seals and 2 bearings.
 
   / Pointers on rebuilding a BCS tiller gearbox #8  
You can pop the little inserts out and make them open bearings, or just leave the inserts in - gear oil will still get to them. Also, odds are the front and back bearings are good, so you won't need them - just 2 seals and 2 bearings.

Hey Folks,
I've just got a leak in the front, behind the 3 dog coupler. Is it possible to just remove that seal and bearing, replace and get back to work without taking the tine-axle apart?
Thanks!
 
 
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