New Chainsaw Brake Dragging

[lloydh]

I just bought a new Efco MT 8200 80cc saw and have noticed that the brake seems to be dragging when disengaged.

 

My dealer is a 3 hour drive away so I'm hoping for some advice from someone with more knowledge of saws than me.

 

The problem manifests in it being extremely difficult to move the chain along the bar by hand (or with a file when sharpening) even with a slack chain.

 

The saw has an outboard clutch drum and the brake assembly is part of the sprocket cover. With the sprocket cover removed the chain moves freely, but as it's tightened on, the part of the brake band nearest the sprocket cover contacts the clutch drum and drags.

 

You can see that this part of the brake band is showing wear in the attached photos — this is after running around 2 tanks.

 

To be honest I haven't noticed anything unusual during use; the brake engages and disengages consistently and the saw accelerates normally. I guess the engine is overcoming the drag without much difficulty.

 

Just to clarify, the brake mechanism itself isn't stuck on — it clicks on/off and stops the chain from spinning in use.

 

Thanks.

Edited July 29, 2017 by lloydh

[spudulike]

The edge of the clutch drum has been running on the brake band to the point it is almost through. The saw is now in a dangerous state with the brake band in this condition and would seriously NOT use it until it is repaired.

It looks like the brake band may not have been seated correctly but it may fail if applied so get a new part fitted under warranty or at your cost!

[peatff]

If it's dragging that much something must be getting hot. It looks like it is not lining up properly. I would be contacting the seller to sort something out even if it means a 3 hour trip.

[lloydh]

Thanks for the help.

 

My dealer immediately offered a warranty repair and I'm hoping to get the saw fixed early next week.

 

My only concern is the unidentified cause of the wear, like an alignment issue as peatff suggested.

 

I noticed that the rim sprocket can slide laterally about 3-5mm on the clutch drum splines — as you can see in my photo below. Is this normal? I could only find videos of rim sprockets on inbound clutches, held on with e-clips.

On 29/07/2017 at 18:32, lloydh said:

 

 

[Daniël Bos]

Sounds like a good dealer!

 

My first thought was that the clutch cover was put back on with the brake engaged, causing this. That would be user error...

 

The lateral play is normal.

[lloydh]

33 minutes ago, Daniël Bos said:

Sounds like a good dealer!

 

My first thought was that the clutch cover was put back on with the brake engaged, causing this. That would be user error...

 

The lateral play is normal.

Yes, tell me about it. Almost all of the brake-related searches I did were new Husky owners who couldn't get their sprocket covers back on. That definitely wasn't the case here and with the tension on my saw's brake I doubt you could actually remove the sprocket cover with the brake on!

 

Glad to hear the play isn't a problem.

 

Lloyd

[Stubby]

In fact lateral play is desirable . That's why its called a " floating rim " . Caters for any slight miss alignment from the bar tip back to the power mate .

Edited August 4, 2017 by Stubby

[spudulike]

The rim is supposed to have end float on it. The issue you have is that the thin section of the brake band has ridden over the pillar that it should sit on. Look at the photo - the drum has been rubbing on the band because it is in front of instead of on top of the alloy cover pillar!

[lloydh]

6 hours ago, spudulike said:

The issue you have is that the thin section of the brake band has ridden over the pillar that it should sit on.

Spud, I agree but I think something's causing that part of the band to leave the channel it should sit in. I have popped it back where it should sit with a screwdriver, but after refitting the sprocket cover and cycling the brake on/off it returns to the way it is now.

 

I know the chance is virtually zero but it's as if the band itself is a couple mm too short and it's moving over as a 'shortcut' to where it's supposed to be.

[bmp01]

5 hours ago, lloydh said:

Spud, I agree but I think something's causing that part of the band to leave the channel it should sit in. I have popped it back where it should sit with a screwdriver, but after refitting the sprocket cover and cycling the brake on/off it returns to the way it is now.

I'm not sure there is much to conclude from the damaged band - with that much change to its geometry its going to adopt a different shape to a new one, plus it's bound to have got blinkin hot so it might be distorted too.

I'd be a bit worried about the wear to the inside of the cover (3rd picture) - it says to me things are not aligned the way they should be, could be the cover or the machined face on the engine case. 

It's got to go back for repair / investigation.   I'd be asking for a replacement cover as well as the brake band, hoping that fixes any alignment issue. If that doesnt fix it, then it's replacement saw time.

 

BMP01