Chain misalignment

[Angry Joe]

Lehigh is running a straight rear axle this year (don't bother trying to talk them out of it, I already tried). We are now faced with the problem of the sprocket moving in relation to the engine in bump and roll, and I'm more concerned about the latter.

How much misalignment can the chain handle before you run the risk of throwing it? I'm worried about the sprocket rotating relative to the pinion when the car goes into roll.



Lehigh Formula SAE Alumni
Team Captain 2002-2003

www.lehigh.edu/~insae/formula (http://www.lehigh.edu/~insae/formula)

[clausen]

Interesting...

I would look at some chain guide devices - even just solid rubbing blocks of nylon or similar, close to the sprocket at each end. Maybe check out some downhill mountain bike guides for inspiration.

Regards

Paul Clausen
Uni of Adelaide

[Angry Joe]

Thanks clausen, I will look into that. I was examining ATV's and it looks like the chain driven ones use a simple non-articulating swingarm. Do any chain-driven quads have articulating rear axles?



Lehigh Formula SAE Alumni
Team Captain 2002-2003

www.lehigh.edu/~insae/formula (http://www.lehigh.edu/~insae/formula)

[Big Daddy]

To answer your question no!!! I have seen some Mini Baja cars that tryed to articulate with a chain and guess what? it didn't work. As for ATV's event the shaft driven swingarms dont articulate. My suggestion (if you are running the same setup as most teams with a zexel just with out the diff) then I would ridgely mount a center section just like the diff and mount your brakes and sproket on that. Because the way I understand it all you are doing in replacing the diff with a straight peice of bar(If I am wrong Please correct me). Lastly even a slightly misaligned sprocket can have bad effects especially on ally sprockets (don't ask how I know that) http://fsae.com/groupee_common/emoticons/icon_wink.gif..... Hope this helps you out.

[Angry Joe]

They are running the straight axle for simplicity and weight. It is not independent at all. Running a simple swingarm seems like a bad idea though, since your roll stiffness in the rear becomes basically infinite



Lehigh Formula SAE Alumni
Team Captain 2002-2003

www.lehigh.edu/~insae/formula (http://www.lehigh.edu/~insae/formula)

[Big Daddy]

Then my only suggestion is to go with a shaft drive. But in reality most teams do run a simple swingarm, because from what I have seen most teams use swaybars that are so stiff they dont get any roll which is exactly what a swing arm is a big anti roll bar. Just my thoughts on the subject. Another alternative is a timing belt like a-mods use they can usually handle some twisting motion.

[Angry Joe]

Swing arm... yeah... http://fsae.com/groupee_common/emoticons/icon_frown.gif

If God is a car guy, then we're going to hell



Lehigh Formula SAE Alumni
Team Captain 2002-2003

www.lehigh.edu/~insae/formula (http://www.lehigh.edu/~insae/formula)

[Big Daddy]

One more quick thought. If you are running a live rear axle you actually want a swingarm. You dont want the body to roll and both rear tires to stay on the ground cause if they do you will have one of the worst cases of understeer possible. With a live rear axle you want 3 tires on the ground during a turn (two front and outside rear).

[Kevin Hall]

Big Daddy

I have to agree with you to a certain degree. The biggest thing that you will notice with the solid axle is that cornering has to be taken a lot more aggressively. If you don't bring the back end around, it'll push the front end in a straight line. In order to compensate for the understeer condition you have to create a lot of oversteer. If you limit the traction of the inside wheel during cornering, you can create that oversteer, or follow through if you will, a lot more easily. It's just like driving go-karts. I'm sure if you love go-karting, you know that the approach to a corner is a lot different. So, if you are saving the weight of the diff, be prepared to make up all that time, packaging, and cost in driver training.

Just my $0.02 for today.

Kevin Hall
University of Saskatchewan
'03-'04 Team Director

[Jarrod]

De Dion? just another option

[gug]

i would investigate those belt drives. sounds like others on here know more about them than me, but some of the a-mods use belt drives over chain for better efficiency i think. just watch out for the rain. http://fsae.com/groupee_common/emoticons/icon_smile.gif

- the problem with the world is stupidity. i'm not saying there should be a capital punishment for stupidity, but why don't we just take the safety lables off of everything and let the problem solve itself?

[Jackson]

gug;

We used a belt drive in our mini baja car last year. Mud and rain have no major ill effects. They are talking of using a timing belt, with cogs and the like, which really can't slip too easily.

Just make sure the belt is tight enough, or when you torque it up you get an awful ratcheting sound.

Also, I would take great care to figure out the belt width. FSAE cars run ~ 3x the peak torque of Mini Baja cars, and we used a 30mm belt.

Amen about stupid people.

Brian
WSU Formula

[gug]

was that belt on a cvt? i heard the comment about the rain from Joe Chung, who races with a cvt in an a-mod.
how strong do timing belts get? ive seen the v-belts in a cvt that can take 300hp engines. are timing belts used to transfer power?

- the problem with the world is stupidity. i'm not saying there should be a capital punishment for stupidity, but why don't we just take the safety lables off of everything and let the problem solve itself?

[Big Daddy]

They use timing belts as the final drive in most harley type bikes(100hp+). The problem with running one on Baja is that the shock loads of landing under full throttle is 10 times the force a formula car can put down even with a formula car dumping the clutch. If anyone is persueing the belt drive search for the Goodyear Eagle PD instead of straight teeth it uses a chevron or V patern of teeth (very hared to get to jump teeth even under larger shock loads. Anyway just some more info to ponder

[gug]

since my signature now whinges about stupid people, i guess is should correct myself when i am being stupid.

you cant use a timing belt on a (belt-and-pulley type) cvt...

- the problem with the world is stupidity. i'm not saying there should be a capital punishment for stupidity, but why don't we just take the safety lables off of everything and let the problem solve itself?

[Big Daddy]

GUG


I was going to say something but my luck I would have proved your signature right also. But at least you caught it.

[Graeme]

Having read the postings regarding the use of a solid axle with chain drive , I would like to add some experiences. I have raced a TQ midget with chain drive on dirt for over 15 years with absolutley no chain guides or tensioners with not one lost chain in that time, admittidley it requires some careful engineering ,axle is made of Aluminiun 1.750" dia, btw engine runs around 145hp , chain must be located near one side of the axle , it is not possible/or sucessful to run the sprocket near the middle as the axle can flex under acceleration toeing out the rear wheels causing severe handling issues,pivot points of the radius rods is also important,Angry Joe , if I knew how to post pics I would it may help you out with some alternartive thinking

[gug]

you can only post pics that are already up on the internet. there is an image button when you type your reply in and you have to put the link to the image in there.
if the pictures are on your own computer, you have to put them on a website first.
sorry to say that i dont know any free place to put pictures up on the internet. http://www.imagestation.com/ is free, but you cant link your pictures to these forums.

- the problem with the world is stupidity. i'm not saying there should be a capital punishment for stupidity, but why don't we just take the safety lables off of everything and let the problem solve itself?

[Dominic Venieri]

<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Graeme:

Angry Joe , if I knew how to post pics I would it may help you out with some alternartive thinking<HR></BLOCKQUOTE>

If you email me those pictures you speak of, I can host them on our webspace for a week or so w/o a problem so everyone can see them.

www.formularpi.com (http://www.formularpi.com)
2003 Formula Student Runner-Up

[Angry Joe]

Graeme, do the midget cars use a conventional chain?



Lehigh Formula SAE Alumni
Team Captain 2002-2003

www.lehigh.edu/~insae/formula (http://www.lehigh.edu/~insae/formula)