Post by blythkd on Aug 30, 2021 20:51:15 GMT -5
Been going a few rounds with a couple of old 385 trimmers trying to get one to work so I would have a straight shaft trimmer to use under barbed wire fences. They're getting pretty old and had crusty carbs which was a challenge because I was having trouble finding kits for them. I finally got one running pretty decent. It would scream pretty well but when you hit some tough grass the head would bog down as the engine still raced pretty well. I used to run into this issue with the clutches on this style of trimmers years ago so I knew the fix. Then I got to thinking maybe I should share in case anyone else is still playing with one of this style of old clutched trimmer.
This style of trimmer utilized 2 approximately 1/8" thick steel S-type clutches. One simply screwed down on top of the other on the clutch adapter shaft. Every time I've pulled a clutch drum off one of these that had a slipping clutch I found the same thing. The 2 clutches were turned approximately 90 degrees to each other. After some time and some slipping, metal from each clutch would wear and "smear" over the other clutch. When the 2 clutches are turned crossways to each other rather than in alignment to each other, as they wear over each other they almost lock together and lose effectiveness.
I used to replace them with new clutches, especially when the units were under warranty, but the issue would usually just repeat itself in fairly short order. So I started removing them, screwed them down on a 3/8-24 fine thread bolt, aligned the 2 pieces and tacked the centers with a mig welder, effectively making a new single piece S-clutch.
If you need to get to the clutches, insert a T25 torx driver into the clutch drum and remove the screw which lets the drum come off. You may have to thread some rope into the cylinder to hold the engine still. The screw is RH thread and remains captive inside the front of the clutch drum. Then you can usually tap the clutches loose with a small punch and hammer.
I just fixed mine this way this evening and went back out to some tough weed hogging and the difference was like day and night. It will lug now. The 385 is a pretty good horse when it's right. Part of the reason I got one running is because I've been working my old ST-260 pretty hard lately and I'd like to take care of it. It's 33 years old this summer and I'd just as soon it lasts me as long as I still care to trim my own yard. If I trash an old 385, I won't shed one tear to toss it. In fact, I recall tossing one like a javelin across the yard several years ago but that's another story.
This style of trimmer utilized 2 approximately 1/8" thick steel S-type clutches. One simply screwed down on top of the other on the clutch adapter shaft. Every time I've pulled a clutch drum off one of these that had a slipping clutch I found the same thing. The 2 clutches were turned approximately 90 degrees to each other. After some time and some slipping, metal from each clutch would wear and "smear" over the other clutch. When the 2 clutches are turned crossways to each other rather than in alignment to each other, as they wear over each other they almost lock together and lose effectiveness.
I used to replace them with new clutches, especially when the units were under warranty, but the issue would usually just repeat itself in fairly short order. So I started removing them, screwed them down on a 3/8-24 fine thread bolt, aligned the 2 pieces and tacked the centers with a mig welder, effectively making a new single piece S-clutch.
If you need to get to the clutches, insert a T25 torx driver into the clutch drum and remove the screw which lets the drum come off. You may have to thread some rope into the cylinder to hold the engine still. The screw is RH thread and remains captive inside the front of the clutch drum. Then you can usually tap the clutches loose with a small punch and hammer.
I just fixed mine this way this evening and went back out to some tough weed hogging and the difference was like day and night. It will lug now. The 385 is a pretty good horse when it's right. Part of the reason I got one running is because I've been working my old ST-260 pretty hard lately and I'd like to take care of it. It's 33 years old this summer and I'd just as soon it lasts me as long as I still care to trim my own yard. If I trash an old 385, I won't shed one tear to toss it. In fact, I recall tossing one like a javelin across the yard several years ago but that's another story.
