Design error of the month!

[Pennyman]

How many design errors can you find?

http://www.civic77.com/cars/lg_RearUpright.jpg

From THIS (http://www.wheelsjamaicahost.com/wheels_forum/index.php?topic=97826.0) forum!

Looks like quite a project!

[Pennyman]

How many design errors can you find?

http://www.civic77.com/cars/lg_RearUpright.jpg

From THIS (http://www.wheelsjamaicahost.com/wheels_forum/index.php?topic=97826.0) forum!

Looks like quite a project!

[Brett Neale]

Well, there's the usual rod-ends in bending... that's usually a given with these puzzles!

Is it just me, or would that toe link hit the ARB arm above it under full droop? The outboard mount for the toe link on the upright is quite long too...

[fixitmattman]

Oh wow....

I believe the correct answer is "moar carbon!"

[L B0MB]

bending moment of lower A arm from push rod to upright

[Ben_MUR]

The a-arms are in single shear (bad enough) but also do not have washers to retain the links in the event of a failure of the spherical joint.

Maybe also not just the usual rod ends in bearing but on the chassis side of the a-arms having incorrect use of tie rod ends. Adjusting these will alter the length of the base of the wishbone.

And the load paths being fed into chassis from the a-arms are not direct, the forces must 'turn corners'

Also, is the ARB actuated from the lower a-arm? I can't really see that clearly, but that will certainly add unwanted bending into an already stressed member. This may also creating stiction in the link and change the mode of operation from the designers intentions.

[Jersey Tom]

That little piece that's anodized red... we all know it should be blue.

[Anvit Garg]

Actually there should be some white in there, wheres your patriotism Tom?

[HenningO]

Holy toe stiffness batman!

[Jersey Tom]

I also like what's holding the UCA on... a single nut, not even a locknut, with half the threads engaged.

I wouldn't even geat NEAR that thing, much less in it, much less drive it!

[PatClarke]

Pennyman,
I will give this the 'Pat Stamp of Approval'

Good find and dreadful car

Cheers
Pat

[Hector]

Yay! I was just waiting for Pat to read this!

[overdrive535]

Two things:

One, the alternator driven by the rear drive shaft made me chuckle

Two, that photo appears to be of the rear of the car. Is it just me or is that brake rotor a little over sized for the rear of the car.

[vreihen]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by overdrive535:
One, the alternator driven by the rear drive shaft made me chuckle </div></BLOCKQUOTE>

Creative attempt at regenerative braking????? http://fsae.com/groupee_common/emoticons/icon_biggrin.gif

[Zac]

actually, my grandfather did that on one of the hillclimb cars he raced in the 60's. The reason he did it that way was to keep the battery charged while he towed(with a strap, not a trailer) it to the race. The mechanical fuel injection setup he used had some real issues with cold starts and he needed all the amperage he could get out of the battery.

Of course, he did take the alternator off once he got to the track and didn't have the mistaken idea that running the alternator off of the driveshaft was somehow taking the load off of the engine, at least when the transmission was in gear. He also still had an alternator on the motor.

But man is this car ever sketchy.

[Wesley]

Actually, a driveshaft driven alternator isn't that uncommon. I've seen it on lots of old circle track cars. I'm sure it has a root somewhere useful.

[overdrive535]

oh, it's not a bad idea for a circle track. But at a road circuit, you better have a good battery if you don't want to die while in the que.

And yes, this thing is Iowa State go-cart shaky

[Wesley]

I looked through most of the thread, and laughable engineering aside, this guy has some drive. Whether or not his design decisions are sound and may kill the driver, the car is a LOT of work that has been accomplished. It's impressive.

[Peter7307]

The original heading for the pic above reads...
"All manner of suspension adjustment and design"

Got that part right.

Pete.

[Peter7307]

Comment from the forum moderator re the driveshaft powering the alternator:

"Innovative race car design elements all seem to come together in this project, like the alternator running off the driveshaft to minimise engine power losses"

Ahh , Ummm, Errr...never mind.

Pete.

[Hector]

Well, there is definitely a reason for doing it. After reduction, the driveshaft will be spinning much slower than the engine, and there will be less parasitic loss from the alternator. This is typically handled with an underdrive pulley that slows the alternator down while on the engine, but another way is to move the alternator to the driveshaft.

Along with reducing parasitic losses, this can also result in a lower cg and a lower moment of inertia. Is it worth it? Eh... not really sure, but there is a reason for doing it. If his battery stays charged throughout the race, then why not?

Remember - the car he probably pulled the alternator from was designed to idle with A/C, radio, electric fans, etc. all on full blast. Your typical race car will be using less power while operating at a much higher engine speed.

[RacingManiac]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by overdrive535:
oh, it's not a bad idea for a circle track. But at a road circuit, you better have a good battery if you don't want to die while in the que.

And yes, this thing is Iowa State go-cart shaky </div></BLOCKQUOTE>

I think quite a few race cars right now uses the alternator on the drive side. Formula BMW cars have it driven on the inboard CV cup...

But to be fair, they usually use an aux. batt when sitting around and waiting...

[Wesley]

I do have to say if this guy was a circle tracker, he's probably used to a carbureted car, which can run on something like 10 amps.

[t21jj]

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">
And yes, this thing is Iowa State go-cart shaky </div></BLOCKQUOTE>

Hey easy on the go-cart it may have been a pile of crap (it was put together in about 24 hours) but the only time it had problems was when we rolled it, the time it hit a curb at full speed, and when someone put E85 in it by mistake (bad idea). It was very hard to kill that thing.