Hi guys.
I recently got a garage find capstan drive Lawn Boy Model L21ZSNA that hadn't run in a few years. The engine was really dirty and had no air filter or cover.
It would not start but it had 90# of compression and had good spark. I cleaned the carb and got a filter on it and it started right up. It would pull on concrete but just spun on the tires in the grass. The drive rollers were really worn down. I have never had any experience with this kind of drive before. I didn't know if I should try to adjust the tension on the rollers or order new ones. I'm not really sure how they are adjusted but there is a rod that runs down along side of the handle bars with a set screw elbow type of thing that I guess you can move to adjust the length of of the rod. Also it looks like the drive rollers are held in with little roll pins. Do you take a nail and hammer to get them out or what is the best way to get them out? Also one side has a plastic plug with a grease fitting on it but the other side has nothing and is full of dirt and grass. Is it important to have these plugs in place? Any information and tips for replacing rollers and adjusting them would be greatly appreciated. I did notice on the Lawn Boy master parts viewer that there was 2 different part no.s for each drive roller. Are they different diameters for different speeds or for some other reason ? I found a set on line for $35 plus shipping. Some places wanted $40 or $50 a piece for them. Thank you.
Jerry
If the tires spin on grass (as you stated) then the problem is not the capstan drive, as it is driving the wheels. If the tires don't spin on grass, then they are worn, or the capstan rollers are worn, or filled up with dirt and grass. I take mine off and clean them with wire brush wheel on my grinder. Yes, you drive out the pin.
There is supposed to be a 3/16" gap between the drive roller and rear wheel. Adjust by loosening the clamp on the rod that runs alongside the handle and pull or push rods until the 3/16" gap is obtained. There should be a grease plug inside the capstan drive roller to periodically put a small amount of grease in. According to my Lawn-Boy mechanic's handbook, adjustment is required when changing wheel height. They also state, the rear wheels are made from a "special" rubber and you can't replace the rear wheels with non OEM ones. I did on my 8255 and it worked ok.
Seems like somebody with a small lathe could machine new capstan rollers if they had a knurling tool.
The 2 different part numbers is because there is a left and right hand drive roller with the "V" cast into the roller should point toward the rear tire.
When driving out the roll pins, I'd support the shaft with a wooden wedge (between the capstan roller and wheel) to help you from cracking the nylon bushings supporting the shaft.
Thanks for the replies. I checked the gap and it looks like between a 1/4 and 3/8 of an inch. That is probably too much gap so I'll try to adjust it a little closer.
I'm not sure if I'll keep this one or not. I don't like how the handle feels. It is hard to just push this mower without the self propel kicking in. The handle folds over too easy to suit me. Maybe I'll get used to it.
I just can't help myself from bringing these things home when I see one setting somewhere. I just like trying to get them going again. I guess there are different size diameters of those drive rollers for slower or faster mowing speeds.
Hey Jeff, do you have a hard copy of the mechanic's manual or on line one. Do you know where you can get a paper version?
Thanks.
Jerry
It sounds like your gap is indeed too great, and when you correct that it should improve greatly.
Capstan rollers come in a variety of sizes, and are easy to find on eBay. If they aren't there, I have boxes of them NOS.
Here is a picture of the difference between the soft rubber self propelled wheels (left) and the hard rubber push mower type (right). The hard rubber ones are almost like plastic.
Well I just installed the new drive rollers and adjusted the gap between the wheels. It works a little better but it still won't propel itself up a hill in my back yard
by itself. The rollers still spin on the tires but won't turn the tires much. I know they must work better than this or Lawn Boy would not have made this system for so many years. I sure like the belt drive system a lot better. I did get them on the right way, thanks Jeff. I am going to order a set of new OEM tires with the right part no. as the Lawn Boy master parts lookup says goes on that mower. There is a place here in Ohio that still has these tires in stock for about $20
apiece. The rollers that I got were the smaller diameter ones. I couldn't tell by the part no. which ones were bigger or smaller. I guess if if I'm thinking right the smaller diameter rollers should produce a slower ground speed than the larger diameter ones. I guess I can slow down a little bit since I am 63, But I still enjoy push mowing a lot. I have a few small yards I mow and use different mowers for different situations. The straight push mowers are a lot better for trimming under pine trees than self propelled ones. Take care fellows. I'll let you know if the new tires make a difference.
Jerry
You're welcome. The 8255 I had worked OK on level ground, but not on hills. The 8255 had a D-400 engine, kind of small CC wise. I've never owned a F powered lawn boy with the capstan drive.
Well I got the new wheels about a week ago and put them on and made sure I had a close gap between the tires and the drive rollers. I had high hopes that this would work like a new one. Boy was I disappointed. It worked better with the old rollers and tires. I was really put out. I put the mower up on my mower work stand and tried to figure out how to get more pressure on the tires and try to understand how everything pivoted underneath the rear axle. That was no help. I tried to just straight push mow with it for awhile but the handle collapses forward too easy. I was not liking this mower at all. I got the idea to just make it a straight pusher out of it. I have another steel deck mower [L21zpn] that is not self-propelled that has been a parts mower. I switched out the top half of the handle bars, drilled a new hole to mount the throttle cable, and switched out the brake cable. I'm cleaning off the engine and mounting plate because it is really grimy. I haven't fired it up yet to see if it will run or not or shut off when I let go of the safety bale. That might need some adjusting. I would like to take out the drive axle and drive shaft if I could but I think if I took the axle out there would be nothing to hold the little drive shaft that comes out of the back of the engine in. And I don't think you can leave that hole open. I believe that I read somewhere that there is a seal in that opening similar to the top and bottom crank seals. If that is the case I'll just leave that stuff there and just maybe take off the drive rollers. Even if I took the drive train out I would probably only save maybe a pound so it probably wouldn't make any difference. If any one has any suggestions or ideas give me a shout. Thank you.
Jerry
I used to think the handle provided a cam like clamping action on the drive rollers, but I think it's just the weight of the mower (not a whole lot considering the engine and deck are very light) on the roller that provides the drive action. Anyhow, Lawn-Boy stuck with this drive system for a LONG time. The later gear drives were way better IMO.
