Hi guys. I have an 028AV that I'm fixing for a friend and I have a question about the chain brake. The saw runs fine and all but when I rev it full throttle and hit the chain brake, the chain stops right away however it seems like the engine "overruns the clutch". It then takes a few seconds for the clutch to engage. Is this normal? I have an 038AV and it does not do this; when I engage the brake on the 038, the engine idles down suddenly and it doesn't freewheel. I took the clutch apart on the 028 and the clutch is totally different than an 038. There is a round part with three "ramps" on it. Is this responsible for the freewheeling or is the saw not supposed to do this. I hope you Stihl experts can help me. Thank you.
Stihl 028AV chain brake
- Thread starter Rubicon
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"When I rev it full throttle and hit the chain brake" Am I the only one that is surprised, appalled, and terrified at this quote? I guess that when the chain brake is engaged, in an emergency situation, it should stop the chain. But to do this to test the system never occurred to me. It seems dangerous, unnecessary and a good way to kill a perfectly nice saw. If I missed something from the Stihl manual on chain brakes, let me know. If I am right though I would not treat my saw that way. Mike 
Well Mike, different strokes for different folks I guess. However I don't need lectures on chain brakes I need help on fixing them. How, may I ask, is one supposed to test if a chain brake is functioning properly other than reving it full throttle and hitting the brake. Isn't this what happens in a real world situation? Hope somebody can help.
treeclimber165
Member A.K.A Skwerl
Sounds like the clutches might be worn or the inside of the sprocket drum could be glazed.
HUSKYMAN
Addicted to ArboristSite
I would look at the clutch shoes and springs
wendell hollis
ArboristSite Member
Hi Rubicon, I was thinking about real world situations concerning chain brakes. I saw decked logs off of trucks or pushed up by skidders. Depending on high the deck is I will saw from the top down or bottom up. I run a 28" bar for slicing up to 17 logs in a pass. I can usually produce a cord of wood every 45 mins. Decked logs present some of the toughest safety challenges. You can't see what your bar tip is doing, logs roll, pinch,twist and then some !! I and my chain brake are very well aquainted. When a brake trips the saw is usually in a under load situation where the rpms are not maxed out as in a hold it in your hand thing. Limbing is a little different, I generally go wide open, most people only go half or so and when it trips there it is less of a load, so it can stop it pretty hard. If I have concerns about it I will run the saw up about 3/4 open let off and hit the brake before the chain speed drops. I don't know how if there is any kind of real measure for that, but I do sleep good knowing it will stop at that Wendell
!! I and my chain brake are very well aquainted. When a brake trips the saw is usually in a under load situation where the rpms are not maxed out as in a hold it in your hand thing. Limbing is a little different, I generally go wide open, most people only go half or so and when it trips there it is less of a load, so it can stop it pretty hard. If I have concerns about it I will run the saw up about 3/4 open let off and hit the brake before the chain speed drops. I don't know how if there is any kind of real measure for that, but I do sleep good knowing it will stop at that Wendell
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