stihl contra

[slowsuki]

flyweel key is missing on my contra. do i need it or will flyweel nut hold it in place? how do you set timing on the contra?

 

[jp hallman]

Well now, I don't think Stihl would go for the cost of maching in the keyway if it wasn't needed! I'm thinking the key is your timing too. But then, I don't even know what a Contra is. I've heard of Sandanista's(sp?) before.

 

[jp hallman]

OK then. You sparked my interest and I checked it out. I'd like to see some pictures of that "...new light-weight...tree felling machine"(from 1959).

 

[slowsuki]

can i use one for a 070,090 or is that part of the 5% that will not inerchange.

 

[JimL]

3x5 metric woodruff key, one from a 090 should fit fine,

 

[slowsuki]

wish mine looked that good, but then i would not use. it thanks for info, now have to find one.

 

[slowsuki]

another stihl lightning cutting up the forest. runs smother than i expected.it's no wonder they were so popular.called it a contra because i see more post about them.

 

[Lakeside53]

Well now, I don't think Stihl would go for the cost of maching in the keyway if it wasn't needed! I'm thinking the key is your timing too. But then, I don't even know what a Contra is. I've heard of Sandanista's(sp?) before.

On tapered shafts the key is not the retaining mechanisum; it's just there to position the flywheel on the shaft. Torque applied to the nut on the shaft presses the flywheel onto the taper slightly "stretching" the flywheel and thereby creating a very high frictional force between the flywheel and shaft.

After it's torqued, you can actually remove the nut also. Great in theory, but I leave my nuts on....

On 031's when converting from points to electronic, I remove the key, reposition the flywheel to the corrected position, and just torque it down.

It VERY important on all tapered fits to throughly DEGREASE both the shaft and flywheel before fitting.

 

[slowsuki]

i thougt that and just eyeballed where key was and it worked great.key was not needed.

 

[Gearhead1]

Jim L, that looks like new wrap (cushion grip) on the handles of those two Stihl saws. If that is true, where did you get it from and how did you put it on?

 

[jp hallman]

On tapered shafts the key is not the retaining mechanisum; it's just there to position the flywheel on the shaft. Torque applied to the nut on the shaft presses the flywheel onto the taper slightly "stretching" the flywheel and thereby creating a very high frictional force between the flywheel and shaft.

After it's torqued, you can actually remove the nut also. Great in theory, but I leave my nuts on....

On 031's when converting from points to electronic, I remove the key, reposition the flywheel to the corrected position, and just torque it down.

It VERY important on all tapered fits to throughly DEGREASE both the shaft and flywheel before fitting.

Do you work these engines or are they "just for show". I can't imagine maching a keyway for no reason other than reference. You'll have to convince me with a little more fact.

 

[bwalker]

Do you work these engines or are they "just for show". I can't imagine maching a keyway for no reason other than reference. You'll have to convince me with a little more fact.

Lakeside is spot on. Ever see the clutch on a snowmobile?

 

[jp hallman]

I believe Lakeside, not you. I don't have time for snowmachines.

 

[Lakeside53]

Do you work these engines or are they "just for show". I can't imagine maching a keyway for no reason other than reference. You'll have to convince me with a little more fact.

Sigh... You'll need to go to the local library and look up:

Bosch Automotive Handbook,6th edition, Page 341 Heading "Tapered connection (tapered interference fit)".

Ever hear of a Morse taper? its used on most decent machine tool, lathes, drill presses etc? Same principle as a flywheel taper fit, but as these don't need an accurate location, no key way is needed. A slight tap on the end is all that's needed to set the taper (instead of a nut).

The keyway is just for reference and to make sure the flywheel doesn't get turned a little "off reference" upon initial tightening of the nut.

Working saws? yes, and hard. MS361's have a cast aluminum key. Virtually no shear strength at all. If this ever spins, it immediately rips out. Rather then replace the flywheel, just reposition it and tighten to the correct torque. Ditto for most other stihl in production less than 044, and all the blowers, weed eaters etc. Want to bet the MS441 has a cast key?

 

[jp hallman]

Sigh... You'll need to go to the local library and look up:

Bosch Automotive Handbook,6th edition, Page 341 Heading "Tapered connection (tapered interference fit)".

Ever hear of a Morse taper? its used on most decent machine tool, lathes, drill presses etc? Same principle as a flywheel taper fit, but as these don't need an accurate location, no key way is needed. A slight tap on the end is all that's needed to set the taper (instead of a nut).

The keyway is just for reference and to make sure the flywheel doesn't get turned a little "off reference" upon initial tightening of the nut.

Working saws? yes, and hard. MS361's have a cast aluminum key. Virtually no shear strength at all. If this ever spins, it immediately rips out. Rather then replace the flywheel, just reposition it and tighten to the correct torque. Ditto for most other stihl in production less than 044, and all the blowers, weed eaters etc. Want to bet the MS441 has a cast key?

No no no...many small engines utilize the "key" for timing. That is what I'm refering to. I wasn't asking you if your engines are worked, I'm asking "slowsuki" about working the saw(Contra). I know a bit about engines and taperd shafts. For sake of argument. If my lawnmower runs upon a rock...the key shears to save the engine. If it just "dents", it's out of time and won't run properly. That's what I'm talking about. I spend plenty of time in the library by the way, wonderful place. Thank you.

 

[slowsuki]

i used the saw for a hour without the key, no problems. i herd you did not need one sometime ago ,but was not positive took a chance it worked.

 

[Lakeside53]

JP - I'm confused - looked like you were asking me (you included my text as "quote". Oh well....

The woodruff key is only a production and servicing (positioning) aid; not a safety breakaway key or for any other purpose.

For those interested in tapered shafts, I'm trying to scan the page referenced above. If it works well enough to read, I'll post it.

 

[Lakeside53]

scanned the page - see attachment. Sorry for the large size but jpeg doesn't work on fine lines..

 

[04ultra]

Boy Lakeside my neck is sore looking at that scan

 

[stihlatit]

JP - I'm confused - looked like you were asking me (you included my text as "quote". Oh well....

The woodruff key is only a production and servicing (positioning) aid; not a safety breakaway key or for any other purpose.

For those interested in tapered shafts, I'm trying to scan the page referenced above. If it works well enough to read, I'll post it.

Lakeside you are right on again as usual. That woodruff key is for positioning and is made of tool steel. It is not a shear pin.

Arnie