Machined vs. forged crankcase DA 3W

[Highlights]

Alright, so I have read all the tech specs on the various websites. DA , ZDZ, 3W etc.
I am aware of most of the pros and cons of forged vs. Machined parts including crankcases.

What are your opinions guys. Da has a machined crankcase. 3W is Forged. Typically I go for a machined product. 3W's wisdom with their TSCS engine is awsome. The motors seem great. The part that I am not too keen on though is the fact that they are forged. Hmmmm. I have seen voids in forged parts before that have let loose when least expected.

Everyone has seen the several ZDZ blowouts rescently.

Any thoughts or reassurance?

[Zee]

One thing, I think you mean Cast not Forged?
Zee

[KrisW]

	Quote: Originally Posted by Highlights
	Alright, so I have read all the tech specs on the various websites. DA , ZDZ, 3W etc. I am aware of most of the pros and cons of forged vs. Machined parts including crankcases. What are your opinions guys. Da has a machined crankcase. 3W is Forged. Typically I go for a machined product. 3W's wisdom with their TSCS engine is awsome. The motors seem great. The part that I am not too keen on though is the fact that they are forged. Hmmmm. I have seen voids in forged parts before that have let loose when least expected. Everyone has seen the several ZDZ blowouts rescently. Any thoughts or reassurance?

3W Investment casts their crankcases. They are a very nice product and the casting quality is top notch. The facility that casts and machines most of the 3W parts also is in business churning out 100's of thousands of small 2-stroke engine parts for a number of major 2-stroke manufacturers. .in other words, you are getting the same quality of workmanship and QC that Kioritz, Ryobi, and others get when they have their parts made.

Up to the point of failure, which is pretty high, castings are as good as anything you can do with a billet CNC machined to shape. When the crankshaft twisted in my 3W 150, I popped the case halves apart to see what was wrong, and the casign actually flexed because the crankshaft was so out of shape it had wedged tightly inside the crankcase as the pieces flexed slightly. They did not break, however. A billet probably would have cracked in the same scenario, because the metallurgy has different properties.

So, rest assured, unless you hit it with a hammer (or a large brick wall at 80 mph) the chances of an engine with a cast crankcase blowing apart are minute at best. The castings are actually overly thick by about 50%, which gives a ton of fudge factor for strength and overall rigidity. Also, remember that every 3W has a 3-year warranty. If the casing cracks, leaks, or develops porosity, you send it back, and they are supposed to replace it under that warranty. I've had one casing that developed a porosity problem (out of about 8-9 3W's I've owned) and the casing was replaced with no questions asked.

Hope this sets your mind at ease.

[flight_stick]

Do you know of a welding procedure to repair these casing. I have a 3w200 with a broken mounting point.

[Hammerman]

You will need to find someone that has and can tig weld. A freind of mine here has repaired a couple of 3W engines that have suffered crash damage to the mounting points.

[Al Lewis]

As Hammerman said anyone that is good with a TIG welder can repair it. The important part is finding someone who won't warp the case with too much heat in the process. I would recommend they clamp it to a ground flat steel plate while welding it.

[Pittsflyboy]

If it's on a DA forget welding it. They make their cases out of 7075-T6 aluminum which is not a weldable alloy, but it is much stronger that the alloys used in cast cases

[flight_stick]

	Quote: Originally Posted by Al Lewis
	As Hammerman said anyone that is good with a TIG welder can repair it. The important part is finding someone who won't warp the case with too much heat in the process. I would recommend they clamp it to a ground flat steel plate while welding it.

Thanks guys, suppose there is no harm on trying. They call this metal Pewter, which is an Aluminum Alloy i think. If it works, cool. If not will just have to replace the casings if I can find them as the motor is obsolete. .