Sidecar Design Formula - IMPORTANT!

[Threewheelbonnie]

Originally Posted by RedMenace

I'd like it "dumbed downed" please and thank you.

Can you simplify it to where I can plug in track width and wheel base, for instance, and arrive at an ideal or ideal range for sidecar wheel lead? I appreciate the article and might understand it when I get a chance to sit down and mull it over, but it doesn't come naturally to me and I am busy trying to rebuild a couple of hacks for the BlackDog.


And Phyliss,
I'd be genuinely interested in how you determine where to set the sidecar wheel lead on your builds, as well. Lot's of ways to skin a cat-how do you do it?

+1

I followed the idea about the tyre contact point moving although it gets a bit deep with jargon (Lineal something), but then there seemed to be a skip where the 10-20% rule just popped up. Looked more like over zealous editing or a need to get it into a set number of pages to me rather than any lack of knowledge or bad information.

I'd like to see an engineering calculation sheet: Enter wheel base, track, rake etc. , do the calcs using the numbers you entered and out pops lead, width and whatever else. Less worry about the text and jargon if you have a diagram and formulae that tell the full story. We can then all put in our own numbers and follow how it works.

The sidecars I've seen set up were basically done by guestimating and testing. 15% of the wheelbase for lead, 1/2" toe in and enough lean out to level on the road outside and off we go testing. If it pulls, pushes or dives you tweak it with a bit more lean, a bit less toe or whatever. It works, but is a bit more craft than science. If that's the answer, there is no need to get upset or try and dress it up in diagrams and calcs. I worked with truck brakes for 15 years and believe me, if you want a trailer to brake well with a truck, leave the PC in the car, jack up two axles and start feeling for the bite while watching the signal line pressure. It looks less scientific but the result is certain as you are setting the function not the mechanism.

Andy

[Nemo DeNovo]

Personally I find that "seat-of-the-pants" engineering usually achieves the best results anyway. If you start with a formula and trust to it 100%, the results are only as good as the formula, so if you don't do any tweaking then you'll never know if you're dead-on or just close. If you do start tweaking then you have deviated from the formula, therefore it was useless to begin with except as a guideline. I think in this case we are talking about a guideline rather than an absolute, and as long as everyone understands that...there should be no problem. I for one am glad to have a starting point to work from rather than blindly wasting my time making mistakes others have already made for me.

[claude]

Nemo wrote:
>>>Personally I find that "seat-of-the-pants" engineering usually achieves the best results anyway. If you start with a formula and trust to it 100%, the results are only as good as the formula, so if you don't do any tweaking then you'll never know if you're dead-on or just close. If you do start tweaking then you have deviated from the formula, therefore it was useless to begin with except as a guideline. I think in this case we are talking about a guideline rather than an absolute, and as long as everyone understands that...there should be no problem. I for one am glad to have a starting point to work from rather than blindly wasting my time making mistakes others have already made for me.<<<

Good points that all shoudl think on Nemo. Almost any sidecarist who is willing to get to know their rig by doing some tweaking on their own will in time benefit themselves. That is IF they record what they did and know how to get back to square one if they get lost.
Talking in absolutes concerning almost anything leads to 'hardheadedness' and can prevent better systems and setups from being tried. When we were racing for a living it was amazing how much of what goes on is 'monkey see monkey do'. That is fine but those who were able to think for themselves were the ones who excelled most times. Sure there are some basics that need to be in place but to not be willing to experiemtn a little sure can limit how things move forward.
In racing and no doubt other worlds there seems to be an ongoing battle between the 'engineer types' and others. It can get funny many times as the engineer types many times get stuck on what the 'paper' says and will condescend to the ones who are willing to step outside of the box. THEN if the outside th ebox guys do well the engineer type do a little reverse calculation to find out why. Then all is well until someoen else step out a little farther etc etc.
I think what was posted was interesting and was good information and we should all say 'thanks' for it. Good info and if we think about what it was saying makes sense. Is it absolute gospel? That is open for opinion and opinions differ. I think Peter Smith would even agree with that.

[Threewheelbonnie]

Originally Posted by claude

Nemo wrote:
>>>In racing and no doubt other worlds there seems to be an ongoing battle between the 'engineer types' and others. It can get funny many times as the engineer types many times get stuck on what the 'paper' says and will condescend to the ones who are willing to step outside of the box. .

Engineering, despite popular opinion is mostly about knowing why you did something and thinking how you might do it better. The engineering here is writing down the settings before you chance them. The rest is just numbers that sometimes help you do it right first time.

OT the Modern design philosopy for the wheel:

The Sales Engineer wants something the customer hasn't seen before.
The Production Engineer wants something that's easy to make.
The Quality Engineer wants something that's easy to measure.
The Safety Engineer wants a wheel that won't roll back.
The FE Engineer wants something that's easy to model.
The Software Engineer wonders what all the fuss is about and goes back to playing chess with a bloke on the ISS via the internet. He later presses Cntrl. Alt. Delete just in case.
The Electrical Engineer is happy the thing won't turn and make connections difficult.

Only the Design Engineer doesn't like the fact it's square

Andy
B.Eng Hons

[claude]

Originally Posted by Threewheelbonnie

Engineering, despite popular opinion is mostly about knowing why you did something and thinking how you might do it better. The engineering here is writing down the settings before you chance them. The rest is just numbers that sometimes help you do it right first time.

OT the Modern design philosopy for the wheel:

The Sales Engineer wants something the customer hasn't seen before.
The Production Engineer wants something that's easy to make.
The Quality Engineer wants something that's easy to measure.
The Safety Engineer wants a wheel that won't roll back.
The FE Engineer wants something that's easy to model.
The Software Engineer wonders what all the fuss is about and goes back to playing chess with a bloke on the ISS via the internet. He later presses Cntrl. Alt. Delete just in case.
The Electrical Engineer is happy the thing won't turn and make connections difficult.

Only the Design Engineer doesn't like the fact it's square

Andy
B.Eng Hons

And the railroad engineer covers the most ground

[Get Back]

.....Now I wish I hadn't bothered !

[RedMenace]

Originally Posted by Get Back

.....Now I wish I hadn't bothered !

Don't be silly. Most of us are very glad you posted that. It is good information to put out there. And if Phyliss can get past name calling and offer specifics and an constructive alternative, even better!

[claude]

Originally Posted by RedMenace

Don't be silly. Most of us are very glad you posted that. It is good information to put out there. An if Phyliss can get past name calling and offer specifics and an constructive alternative, even better!

Yes, I agree and am glad it was posted. Got more?

[koifarm]

Getback,
We are glad that you posted that, please don't stop posting good info since we all may need that input to resolve a problem or just to find out more about what we are doing....
Don't even think for a moment that you caused any uproar, mate, if anyone did it was the sort of negative post that was displayed by one of the inmates. Instead of being constructive the post was derogatory and not in keeping with the spirit of the forum which is what caused the ripple of comments in regards to that post.
Forums are kind of self policing, and this thread is a good example of how that works.
Keep on posting the good stuff, it's gonna help someone somewhere figure out an answer to their problem or just add to the general pool of knowledge that we all draw on in times of puzzlement.
koi

[Get Back]

[quote=RedMenace]Don't be silly. quote]


..........Silly? .....Moi?

[Nemo DeNovo]

Originally Posted by claude

Yes, I agree and am glad it was posted. Got more?

+1
All other detractors line up for your beating

[claude]

Originally Posted by Nemo DeNovo

+1
All other detractors line up for your beating

Is a tractor the opposite of a detractor? If so I think there are more tractors here than detractors.
I be a tractor...all tractors raise their hand.

[koifarm]

Originally Posted by claude

Is a tractor the opposite of a detractor? If so I think there are more tractors here than detractors.
I be a tractor...all tractors raise their hand.

John Deere heere raising the hand of a tractor!!!

[Nemo DeNovo]

Originally Posted by claude

Is a tractor the opposite of a detractor? If so I think there are more tractors here than detractors.
I be a tractor...all tractors raise their hand.

I got a Ukrainian tractor. Does that count?

[claude]