Plastic handle repairz stihl ms390
- Thread starter MartDalb
- Start date
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Hey 
Having tried and failed adhering / rebonding the “plastics” I can tell you it doesn’t work. It’s not your typical plastic that Stihl use, it’s a fibre reinforced composite. Epoxy etc won’t hold or even bond to it.
It’s quite a common place for cracks to occur.
I’d suggest any of the following -
1) Leaving it.
2) Drilling a small hole at the end of that crack to stop it getting worse.
3) Cut it off cleanly. Finish off with a wet sand and polish it.
.
Did I say it’s common?
I opted for the “leave it” approach.
Either way, it’s no biggie.
Having tried and failed adhering / rebonding the “plastics” I can tell you it doesn’t work. It’s not your typical plastic that Stihl use, it’s a fibre reinforced composite. Epoxy etc won’t hold or even bond to it.
It’s quite a common place for cracks to occur.
I’d suggest any of the following -
1) Leaving it.
2) Drilling a small hole at the end of that crack to stop it getting worse.
3) Cut it off cleanly. Finish off with a wet sand and polish it.
.
Did I say it’s common?
I opted for the “leave it” approach.
Either way, it’s no biggie.
Stop-drill the crack, use a small maybe 1/8" bit. Drill right at the end of the crack. You can put a pin in it if you can wedge one in there to stay put and eliminate the ongoing strain.
Would Gorilla Glue not work??? At least on the bottom side at least, to stiffen it, leave the top open and let the Gorilla foam upwards? At least you can put a clamp in that location for some type of glue/epoxy. It also depends on what the structure is on the bottom side.
I had the same thing on this little Homelite, but it was much worse, cracked almost all the way across where you'd put your foot through. It's more el cheapo plastic than Stihl for sure, but the Gorilla did the trick. It's much stiffer now, probably then when it was even brand new...
Would Gorilla Glue not work??? At least on the bottom side at least, to stiffen it, leave the top open and let the Gorilla foam upwards? At least you can put a clamp in that location for some type of glue/epoxy. It also depends on what the structure is on the bottom side.
I had the same thing on this little Homelite, but it was much worse, cracked almost all the way across where you'd put your foot through. It's more el cheapo plastic than Stihl for sure, but the Gorilla did the trick. It's much stiffer now, probably then when it was even brand new...
Vince Roth
ArboristSite Lurker
You could try this -
yeah and if the bottom is flat, it could probably be fiberglassed? At least, that used to be a quick fix in order to strengthen motorcycle plastics, back in the day. Those were flimsy, flexible plastics to begin with though.
If you aren't too concerned with cosmetics, the easiest way to effect a strong repair is to drill a series of small holes along either side of the crack, squeeze some good epoxy (JB-Weld will do) into the crack and stitch it together with small copper wire pulled tight. Finish it off by filling the stitching with epoxy to form a smooth bead on either side of the crack. Just heat welding the crack or glueing it together will NOT last, you need mechanical reinforcement like a metal plate either side, riveted together or the stitching method. Fiberglass repair will also work and can be made to look pretty but if you don't know what you are doing with fiberglass and resins the results might not be good.
I Would have replaced it, but I have not had Any luck finding Any aftermarket part for it, here in europe.
What is hsg?
Replacing this part would take me an hour or two and be much more long term, bit prices and supply is not the same here in EU.
Working on it.... If it wont hold up ill replace the entire handle, but I have some questions about that.
I can only find the handle that fits the old version, mine is the newer version.
Which means, if i buy the replacement handle, I have to buy a new air filter and cover part to fit it.
Will that be enough to rebuild it?
I Will have to take off the decomp valve and put in a screw instead, because the old version handle does not support decomp valve.
Attached Pictures.
It seeems strong, and I can stress the plastic without problems, should i weld it topside as well?
I have only welded it on the non visible side for now.
I can only find the handle that fits the old version, mine is the newer version.
Which means, if i buy the replacement handle, I have to buy a new air filter and cover part to fit it.
Will that be enough to rebuild it?
I Will have to take off the decomp valve and put in a screw instead, because the old version handle does not support decomp valve.
Attached Pictures.
It seeems strong, and I can stress the plastic without problems, should i weld it topside as well?
I have only welded it on the non visible side for now.
Attachments
Hmm, late to the party, was going to say weld, and now I see you have.
Looks a bit on the hot side, but slice off some bits from the handle somewhere else, also good for filling etc on the top side if you can cool the soldering iron to a more usable temp.
Looks a bit on the hot side, but slice off some bits from the handle somewhere else, also good for filling etc on the top side if you can cool the soldering iron to a more usable temp.
All else fails, the different color " duct tape" fix all with reinforced bailing wire.
