• Welcome, Guest! We hope you enjoy the excellent technical knowledge, event information and discussions that the BMW MOA forum provides. Some forum content will be hidden from you if you remain logged out. If you want to view all content, please click the 'Log in' button above and enter your BMW MOA username and password.

    If you are not an MOA member, why not take the time to join the club, so you can enjoy posting on the forum, the BMW Owners News magazine, and all of the discounts and benefits the BMW MOA offers?

  • Beginning April 1st, and running through April 30th, there is a new 2024 BMW MOA Election discussion area within The Club section of the forum. Within this forum area is also a sticky post that provides the ground rules for participating in the Election forum area. Also, the candidates statements are provided. Please read before joining the conversation, because the rules are very specific to maintain civility.

    The Election forum is here: Election Forum

Is there a "Weird Award" for engineers?

Jeff488

Aspiring Profligate
I know that a lot of those of us who work on our beemers have occasionally wondered what the engineers could have been thinking.
I read somewhere that someone thought that all the engineers who worked on the German enigma crypto machine design found employment with BMW after the war.

Well, while working on the reconditioning of my recently acquired '65 Allstate/Puch "twingle" 250, I think I found where those enigma engineers rejected by BMW found a job.

Criminy dutch, Alice, it's like they designed the twingle engine and then, apparently believing that wasn't odd enough, decided to make it run backwards! This I discovered while setting the timing for the first time. I never saw a motorcycle engine that turned opposite to the bike's wheels, but this one does. I'm not counting engines that turn parallel to the bikes centerline. That makes sense of another sort.

Furthermore, the designers apparently had access to a cheap supply of nuts and bolts in 9 and 11 mm sizes. Where one usually finds a 10mm hex head on other bikes, on the twingle there will be an eleven, and where you'd expect to find an 8mm there's a 9mm.

The bike is built like a tank. It has a 7 plate clutch in an engine delivering 16.5 hp when new. Just a bit quirky, but that gives it character.

Additionally, the way the rear hub is assembled I can't begin to describe. I bet it took me half an hour today to figure out how to get it apart so the bearings can be lubed. The only available repair manual doesn't help much, but that's not a big deal. I'm having a great time rescuing this old timer, and there's a guy in Milwaukee who specializes in Puchs. Can't ask for more.

Should be back on the road in a couple months.

Let the weirdness continue.:boldpurpl
 
decided to make it run backwards! :boldpurpl

Running backward isn't that unusual - the Yamaha v-twin of the early 80's (XV750 & 920) ran backwards. The idea was to send the vibration to the back of the bike - which seemed to work as I encountered vibration failures of bodywork. It also is why it wasn't successful as an AMA flat-tracker as Kenny Roberts and Yamaha hoped - I thought the rotation had an effect on off corner traction. And just in the last couple of months I read an article about another MC motor that ran backwards - can't remember what though.

Good luck on the project - I'm envious.
 
Early Yamaha two stroke twins ran backward as well.

I worked on German cars for most of my life and some of their engineering came into question several times over the years.

The brother in law that needed a job and was hired by VW to design air cleaners for VW busses.

Audi's inboard disc brakes that required you to dissemble half the car to replace the disc.

I've had many conversations over the years with service personal from verious auto and MC makers. It seems quick assembly is the main concern, service is secondary.
 
OK, it was my first time seeing an engine turn backwards. They still seem to be going for the "quirky" award.
Here's the first day on the lift. It's quite a bit barer now.
First day Dec.4,2013.jpg
Got the engine out here.
photo 1.jpg

The rear wheel and shocks are off now and the swing arm is next. After that the steering head and front wheel bearings get the business.
Lots of cleaning yet to do. It has dirt there that was embedded when LBJ was president!
 
At one time split cylinders weren't all that unusual. No one had any idea how to use expansion chambers or aimed ports to build an efficient two stroke. The primary methods for preventing the fuel charge from blowing out the exhaust were big deflector vanes on the top of the piston (with resulting low compression, piston weight and heat issues) or split cylinders where the wall between the cylinders served the same role as the deflector vane. The split cylinders ("Twingle' in Puch speak) may seem odd, but they allowed higher compression and flat topped pistons.

http://en.wikipedia.org/wiki/Split-single
 
I don't care what everyone else in the world says, I think it's weird.
OK, maybe just quirky.
I like it.
 
At one time split cylinders weren't all that unusual. No one had any idea how to use expansion chambers or aimed ports to build an efficient two stroke. The primary methods for preventing the fuel charge from blowing out the exhaust were big deflector vanes on the top of the piston (with resulting low compression, piston weight and heat issues) or split cylinders where the wall between the cylinders served the same role as the deflector vane. The split cylinders ("Twingle' in Puch speak) may seem odd, but they allowed higher compression and flat topped pistons.

http://en.wikipedia.org/wiki/Split-single

The Wiki provides the explanation, this engine configuration is credited to an Italian.....:nyah

However, the previously mentioned VW and Audi auto design features will always be considered "unique" and surely the product of the marketing department or some beret topped fashionista clad in a $100 black tee-shirt who works in the "Design" department which isn't in Engineering. You know, that "Design" department.......where they drink wine and lunch on crackers and Brie.
 
Well, you have to give him credit. He was sent there to close the place and he came up with a design that saved the company. Not exactly the Augean stables, but pretty good for an Italian.:bow
Besides, without him I wouldn't have my project.
 
Well, you have to give him credit. He was sent there to close the place and he came up with a design that saved the company. Not exactly the Augean stables, but pretty good for an Italian.:bow
Besides, without him I wouldn't have my project.

I suppose you could thank Alessandro Volta and Luigi Galvani too. :)
 
Early Yamaha two stroke twins ran backward as well.

I worked on German cars for most of my life and some of their engineering came into question several times over the years.

The brother in law that needed a job and was hired by VW to design air cleaners for VW busses.

Audi's inboard disc brakes that required you to dissemble half the car to replace the disc.

I've had many conversations over the years with service personal from verious auto and MC makers. It seems quick assembly is the main concern, service is secondary.

Inboard disc brakes were designed in an effort to reduce unsprung weight. Used on 100's of cars from Jag E-types to Olds Toronados. Nothing to do with quick assembly…

Cheers!

John
 
Bad is still bad

Just an engineering choice. Engineering is about compromise; assuming competence, there are no "bad" choices, just ones that align more or less with your desires. The reduction in unsprung weight (and corresponding increase in handling) more than offset the increase in labor to replace the rotors. I think anyone who has driven an E-Type would agree...

Besides, just replace the pads often enough (mere minutes of work) and you'll never need to touch the rotors.

Happy New year!

John
 
Last edited:
Just an engineering choice. Engineering is about compromise; assuming competence, there are no "bad" choices, just ones that align more or less with your desires.

John

If you actually believe this you have never, ever, seen some BMW motorcycle sidestand designs. :)
 
If you actually believe this you have never, ever, seen some BMW motorcycle sidestand designs. :)

I tip my hat to you, sir... :1drink

I have a 2002 S54 M Roadster. My friend and I often take it to conventions in SF (two-seaters get to use the carpool lanes). As we notice yet another of its many quirks, we will share a knowing look and declare "Engineered like *no* other car in the world!".

Ah, but that glorious engine. Makes everything all right, it does.

Cheers!

John
 
Inboard disc brakes were designed in an effort to reduce unsprung weight. Used on 100's of cars from Jag E-types to Olds Toronados. Nothing to do with quick assembly?

Some Tyrrells used them on all four wheels. You can see the faired disc covers here behind the rad exits and between the front wheels.

http://en.wikipedia.org/wiki/File:Tyrrell_006_Donington.jpg

However, the added complication and additional parts (drive shafts and cv joints) pretty much negated the theoretical advantages. Now a moot point with lightweight calipers and discs.
 
..............
Besides, just replace the pads often enough (mere minutes of work) and you'll never need to touch the rotors.
John

Obviously you live in a temped climate, through the N and NE the tons of salt applied to the roads for ice and snow, will eat any ferrous materials, and set up electrolysis with several other materials. Only plastic is safe.

And of course to disassemble anything under a car gets interesting when the former hex head bolt looks more like a rivet head once the rust is removed, and everything is seized. Mechanics in the N should make 2-3 times/ hr, what one in AZ makes, if being paid via flat rate.
 
Back
Top