Stripped Stud Threads on a Stihl 192TC

[Wood Doctor]

The owner brought this saw to me after he wrenched the bar nut way too hard and stripped the coarse internal female threads used by the collar screw. I am sure that likely many here have run into this failure. The engine still runs well. As you know, this saw only has one bar stud and likely needed two. Looks like somebody already tried thread adhesive and that failed. Any idea what might be the easiest and best way to fix this without buying a new case? I'm all ears. TIA.

 

[gary courtney]

The owner brought this saw to me after he wrenched the bar nut way too hard and stripped the coarse internal female threads used by the collar screw. I am sure that likely many here have run into this failure. The engine still runs well. As you know, this saw only has one bar stud and likely needed two. Looks like somebody already tried thread adhesive and that failed. Any idea what might be the easiest and best way to fix this without buying a new case? I'm all ears. TIA.
View attachment 980777

Time sert

 

[cscltd]

Can try Stihl part # 1123 664 2405
it’s an oversized stud made when original is stripped

 

[Wood Doctor]

Can try Stihl part # 1123 664 2405
it’s an oversized stud made when original is stripped

I had no idea this OEM part existed. To my knowledge, neither the Stihl 192T service manual nor the IPL says anything about it. May I please ask where on earth did you find this part and part number? Regardless, I will call a local Stihl dealer tomorrow and see if they have one or can get one. I assume the outside threads are the same so I can use the same typical Stihl lug nut.

Note to Gary Courtney: this collar screw uses a coarse, non-metallic thread that fastens to the case, so I doubt a Time Sert would work, but I could be wrong.

 

[Dean-O]

I had no idea this OEM part existed. To my knowledge, neither the Stihl 192T service manual nor the IPL says anything about it. May I please ask where on earth did you find this part and part number? Regardless, I will call a local Stihl dealer tomorrow and see if they have one or can get one. I assume the outside threads are the same so I can use the same typical Stihl lug nut.

Note to Gary Courtney: this collar screw uses a coarse, non-metallic thread that fastens to the case, so I doubt a Time Sert would work, but I could be wrong.

My shop stocks couple different oversized Stihl OEM bar studs for the plastic case saws. I use them all the time when the bar stud hole is stripped out. They work great

 

[cscltd]

They don’t show it for ms192, but same stud is used on ms250 and ipl shows the 2405 as oversize. Not sure why it doesn’t show it for 192 though- stihl is funny in stuff like that- could be that there is not enough meat for oversized?

 

[jackjcc]

The oversized exist for metal saws too. I had to use one on an 036 and only learned they exist here through master techs. Stihl isn’t forth coming with technical knowledge or tooling unfortunately.


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[67L36Driver]

They are a common repair on 029 ‘farm boss’ types. I’ve used them several times for those.

It wouldn’t surprise me they have others for the smaller saws as well. [emoji848]

 

[Wood Doctor]

Thanks guys. Ordered a new one today, $10 apiece, but I guess it's worth it. Saw is a dead puppy without it. I guess it's just a tad longer, but the IPL for the 290 shows the threads (part #12 below) as typical (say 1.25) not coarse like the original:

And, on the 290 there is a lip for the bar's wider slot. The 192T has a narrow-slot bar. This part is on back order, of course. Owner joked that they are hard to keep in stock because "These bar studs are notorious strippers."

Also, it worries me that the reason Stihl does not show par #12 above on the 192's IPL is because Stihl offers no part like #5 with a coarse thread and no lip required for the wider bar. So, if that part is to work on a 192, I will have to machine off that lip and pray that there are enough threads for the bar nuts to hold the bar tight to the case. Otherwise, I will have to somehow add threads, and the steel used on collar screws is tough stuff. In short, guys, I am still not out of the woods.

I cannot recall ever stripping a collar screw (stud) on a chain saw, but several members here have told me that tree service companies are indeed experts at it. I have to agree.

 

[Captain Bruce]

The owner brought this saw to me after he wrenched the bar nut way too hard and stripped the coarse internal female threads used by the collar screw. I am sure that likely many here have run into this failure. The engine still runs well. As you know, this saw only has one bar stud and likely needed two. Looks like somebody already tried thread adhesive and that failed. Any idea what might be the easiest and best way to fix this without buying a new case? I'm all ears. TIA.
View attachment 980777

I have done this repair on several Stihl saws. I clean out the striped bore, blow it clean. Than I warp a fine wire around the thread lands on the new stud. Finally, I introduce a small amount of JB Weld. Leave it for 2 days. After that, you could hang meat from the bar nut....

 

[Wood Doctor]

I have done this repair on several Stihl saws. I clean out the striped bore, blow it clean. Than I warp a fine wire around the thread lands on the new stud. Finally, I introduce a small amount of JB Weld. Leave it for 2 days. After that, you could hang meat from the bar nut....

Will that work on both the coarse threads like those on the 192TC and the more typical M8 stud threads? Regardless, it seems like if the case threads are stripped, the wire has nothinng to grab and serves only as a filler. The JB Weld is doing it all. --- Anyway, please see thread #12.

 

[Wood Doctor]

Good news, I believe. I gave up on the coarse threaded collar screw (stud) and used a typical M8 x 1.25 threaded one that's used on many Stihl saws. First, I used an M8 X 1.25 tap on the same case hole and threaded it all the way in. I was fearful that there were not enough good threads remaining near the surface, so I tried screwing in the collar screw by itself first. Lo and behold, the deep threads pulled it in tightly.

So, I removed it, coated both the hole and the collar screw threads with Loctite Red 271 extra strength thread locker, and screwed it back in again to final position (double nut technique). It went in tight as a drum. I'll let it sit for two days as Captain Bruce suggested. I think we are good to go!