I thought glued on tranfer cover was was amazingly stupid and now this- garbage saw imo- I stick with rebuilding older quality saws- almost like china parts- like they care to improve- NOT as long as long as the money keeps flowing in
Stihl with aluminum screws?
- Thread starter Ricardo Oscar Fiegel
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Tom, I see it more as a removal concern than a install concern, give them a few years to corrode in the atmosphere where I live and they may be prone to snap off on removal, heck even steel screws are known to break off on removal around here. For my own use aluminum screws will never be used for assembly, they can all go in the scrap metal bucket.
I don't even like the steel self tapping screws Stihl has used for a long time on the cheaper saws.
I had to fix a 009 muffler (a strange design) where those stripped out the aluminum housing. I did it proper drilling and tapping then installing stainless cap screws. A permanent fix.
I had to fix a 009 muffler (a strange design) where those stripped out the aluminum housing. I did it proper drilling and tapping then installing stainless cap screws. A permanent fix.
You can't predict whether a screw of a given material will break in tension or strip the internal threads of a mating piece of different material by simply comparing the strengths of the two materials. The threads are primarily in shear (not tension) and the shear area increases with greater thread engagement. In other words, you can reach the tensile yield of a high strength screw in a soft female thread by increasing the thread engagement length.*
The snug then turn another 90 degrees tightening instructions makes me believe the aluminum cap screws are torque to yield fasteners (AKA TTY; stretch bolts; turn-of-the-nut) in order to control the clamping pressure and sealing between the case halves, and a steel screw that matches the "stretchiness" of an aluminum fastener would be unreasonably small.
*The rule-of-thumb for UNC threads is that approx 3 threads is enough to break the screw if the screw and internal thread are of similar materials.
The 500, 462, (241 and 400 maybe) use aluminum case screws.
PO Ackley, who I'm sure was referring to ordnance steel, said that the first two threads carried 90% of the load and the fifth thread was always loose.
Off on another tangent, the connecting rod cap bolts on John Deere diesel engines are not reusable, some of them anyway. Torque once and that's all you get.
Friend of mine has one in the bottom of a combine engine that you can see with a scope, no good way to take the pan off without removing the engine. No idea what they are made of , but I doubt aluminum.
I'd rather steel screws that are torqued properly and coated with an anti-seize compound during assembly.
They are making things cheaper, not better. Although the overall designs might be better.
I'm happy with my old saws easy to work on, no limiter caps, restricted exhaust, or auto tune
Torque to yield screws. Been using the in automotive head bolts for years. Designed not to loosen. Not weight reduction. A more perfect tension for tightening.
Just normal stuff if you spent time in the auto industry.
Just normal stuff if you spent time in the auto industry.
Understanding the reasons behind the introduction of such fasteners (TTY) for a certain type of application like aluminum cylinder heads, I guess such screws don't necessarily have to be made of aluminum.
Not that it matters much in practice, because even if they are made of steel, they will still be disposable.
I suppose Stihl may have decided to make them out of aluminum, for one or two reasons. Presumably the steel ones would have to be really small in diameter to get the clamping force needed in this case. The weight savings may be an additional (or only) advantage.
Aluminum is also cheaper than stainless steel, although perhaps the likelihood of corrosion is also less if aluminum screws are used.
I could not tell from the diagram if locating pins exist or not.
The thin modern magnesium castings might creep a tiny bit as they age and the aluminum screws could deform better and keep the same force?
https://cdn.imagearchive.com/arbori...528d8880b6e79e246abea016418e8da5ebfc9a0f17c64
The thin modern magnesium castings might creep a tiny bit as they age and the aluminum screws could deform better and keep the same force?
https://cdn.imagearchive.com/arbori...528d8880b6e79e246abea016418e8da5ebfc9a0f17c64
I remember the good ole days building SBC/BBCs. Could reuse all the bolts. Clean them up and run through a die. Chase all the bolt holes with a tap. Only changed the rod bolts.
Since I started at GM in the 80s, those "Good old days" were well on the way out. But then again, I was the Olds diesel guy. Explains a lot, doesn't it.
Dodge did the stretch bolt thing years back on their Caravans, head bolts could not be reused and many of those engines came in needing head gasket replacements, always had to order new head bolts for each job.
Much ado about nothing I'm thinking. About all those screws do is pull the crank case halves together. Very little pressure in there. And, once you take those screws out the case halves don't exactly fall apart laugh out loud.
Good ole days was before the 1980s, when you could unbolt a 250-I6 and pop a LS7 454 right in the same engine bay, transmissions and rears too. Even cross swaps between chevy/pontiac/olds/buick were pretty easy. Some bell housings were different.
I had a friend with a ratty Olds 88, he put a 455 and muncie out of a GTO in it. That car surprised a lot of the later "smog" hot rods
I still have my first car, 68 rs/ss camaro with a 69 LT1 corvette motor. Glad I never sold it. Worth > 30 times what I paid for it.
HansFranz
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I had a 69 Goat with 400 BB and M21 gearbox...you could hit the gas at 70mph in 3rd gear and spin the wheels...good times. Passed anything but a gas station.
Friend of mine had a 76 TA with a 455 and 4 sp.
55 in 1st, 85 in 2nd, 115 in 3rd, and then the tires would hook up in 4th. Could shift back into 2nd and do it all again lol. Good times.
RIP Ox
A friend had the pre-smog version of that car. He raced a 351 Boss Mustang and missed the 1st shift, went from 1-4th, still beat the Mustang
Yep, that’s called torque-to-yield. Totally overkill for case bolts if they just used decent hardware like they have for the last 80 years. I still think this is going to cause a lot of snapped bolts stuck in cases, and it’ll be a nightmare for customers with all the extra labor.
Yup, remove a snapped off bolt or fix a stripped case..........are they using these in the plastic case saws?
