Cita
|
| posted on 5/10/04 at 06:04 PM |
|
|
Thanks for the explanation Peteff but as Sid said" keep the lower wishbone parralel to the ground and the upper wishbone parrarel to the
lower" how can Sid mean that the upper wishbone is angled up?
|
|
|
|
|
Peteff
|
| posted on 5/10/04 at 07:01 PM |
|
|
Cita, read the text....
set the upper parallel to the lower,or bring the inner pivots a little closer together. English may not be your first language but the little
word 'or' is the one that makes the difference. Do you speak French, if so it's 'ou'.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
|
|
|
stephen_gusterson
|
| posted on 5/10/04 at 07:47 PM |
|
|
Im looking forward to syds reply
atb
mr fence sitter
|
|
|
dblissett
|
| posted on 5/10/04 at 09:00 PM |
|
|
equal length wish bones?
syd i mainly agree with what you are saying but i was told a good rule of thumb was to have the top whisbone 2/3 the length of the bottom wish bone
and not to have both wishbones pararel
also the pivot point centers at the wheel end of the wish bones should be slightly more than at the chassis location points
i think that's what you are saying
ps if my irs is still wrong its staying that way or my car will never make it to the road
dave
[Edited on 5/10/04 by dblissett]
|
|
|
stephen_gusterson
|
| posted on 6/10/04 at 09:46 AM |
|
|
I did similar, but drawn out on wallpaper in higher and lowest positions.
still screwed up tho cos I measured pivot points at the extremities of the hubs, and not at the actual ball pivot centre.
had to make the whole fffing front suspension again.
Thats why im an advocate of dont play with stuff you are not sure about, when it works as is...
atb
steve
I have no idea where my roll centre is, I just want to drive a car. If it handles like a typical saloon, i will cisider it a success. Im no racer, and
neither is my car!
[Edited on 6/10/04 by stephen_gusterson]
|
|
|
Cita
|
| posted on 6/10/04 at 06:39 PM |
|
|
Sorry Peteff,i do understand the word "or"
'just was temporary reading what i wanted to read if you know what i mean.
The French word "ou" means nothing to me as i'm Flemish but i know the Flemish equivalent which is "of".
[Edited on 6/10/04 by Cita]
|
|
|
dblissett
|
| posted on 6/10/04 at 07:01 PM |
|
|
roll centre
i think we might of found syd's roll center
dave
|
|
|
MikeRJ
|
| posted on 6/10/04 at 07:45 PM |
|
|
quote:
Originally posted by Syd Bridge
(I think the hallowed Mr.Staniforth even describes this in his books.)
Yep, he calls it his "string computer". He also advocates working out roll centers however...
|
|
|
Rorty
|
| posted on 6/10/04 at 09:28 PM |
|
|
quote:
Originally posted by Syd Bridge
Ok you lot, listen up, just for once!
1..As I put before, the opinions I put are not only my own, but also those of a couple of well known designers.
2..You don't have to 'do as I say'. I just offer what little help I can, and try to lead in a safe and relevant direction. You can
'Go Your Own Way', as Fleetwood Mac sing.
3..You can believe what you read in books, or use your own brains. (But if you believe what's written in books, give up your build now, because
the world is going to end tomorrow. I know, I read it in a book.!!) 
Cheers,
Syd.
Now, back to work so I can get home for the weekend.
Syd, why should we listen to you? You've not proven anything or offered any supportive evidence of these so called insider friends of yours.
Either name them and their expertise or shut up about them.
What's the difference between believing "what we read in books" and believing your rantings?
Try and see it from the point of view of the other posters on this forum. Your arrogance and generally obnoxious attitude is neither helpful to the
forum nor does it do you any service. 
This is not intended as the beginnings of a flame war, just the voice of a very fed up enthusiast.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
|
|
|
Rorty
|
| posted on 7/10/04 at 08:45 AM |
|
|
quote:
Originally posted by Syd Bridge
Like a beasty that won't flush..it just keeps coming back...............
I've said nothing that I know to be untried or untested, and not in current use.
I suspected you would again reveal your neo-Neanderthal antipodean variation of rebuttal.
You may or may not have made untruthful statements, but the point is, Syd, you still haven't substiated anything you've ever commented on
in this forum. For all we know, you may be a waiter in Earls Court who bases his submissions on articles he reads in the motoring press during his
coffee breaks.
If you've got something of value to offer, or even something constructive to say, we'd all be really interested in listening and learning.
Otherwise, stop filling up this forum with your ignorant, arrogant and vitriolic claptrap.
Cheers, Rorty.
"Faster than a speeding Pullet".
PLEASE DON'T U2U ME IF YOU WANT A QUICK RESPONSE. TRY EMAILING ME INSTEAD!
|
|
|
pbura
|
| posted on 8/10/04 at 10:43 AM |
|
|
Syd's challenge led me to do a bit of research about roll centers (on my lunch hour  ). He is right about the geometric roll center model
being considered obsolete in some circles. The newer methodology is to determine roll centers in the lab or at the track using fancy data acquisition
technology that takes into account compliance in suspension components.
He is, however, wrong about roll centers being unimportant. Roll center height DOES determine body roll, and also how much vertical jacking force is
generated by the suspension links. These both affect the tire contact patch.
Interestingly, the old (but new to most of us) geometric models can still give good results. A couple of enlightening discussions:
http://p081.ezboard.com/fdsrforumcarbuilding.showMessageRange?start=21&stop=40&topicID=420.topic - Please note contributions by Jay Novak
(vehicle dynamics specialist with Ford and former head of their NASCAR program).
http://www.auto-ware.com/ubbthreads/showflat.php?Cat=&Number=489&page=0&view=collapsed&sb=5&o=&fpart=1 - Using Ortiz's
rule of thumb of 75% of loads being generated by the outside wheel, the recommendations of Staniforth and Smith for controlling the RC laterally make
sense. With a centrally located geometric RC, the force vectors are at equivalent angles so that the force-based roll center is about the same height
as the geometric roll center.
Syd's recommendations for parallel or near-parallel wishbones put the RC at ground level where force vectors are near horizontal. Because of
this, jacking is not an issue.
The parallel-ish wishbones would work well for a race car set up with, say, 3 degrees negative static camber, because the camber on the inside tires
would never go positive. Grip would be fine throughout the range, because racing tires can function well with large amounts (5+ degrees) of negative
camber. Us hoi polloi would never put up with the tire wear.
This setup would be crap in a road car running -1 degree static camber.
I wasn't previously aware of the jacking forces caused by wishbone suspensions with high roll centers. This explains why IRS cars, such as the
Elise and the new Caterham, have such low roll centers. Solid and de Dion axles have horizontal load paths, so do not have this problem.
Pete
Pete
|
|
|
MikeP
|
| posted on 8/10/04 at 01:13 PM |
|
|
quote:
Originally posted by pbura
The newer methodology is to determine roll centers in the lab or at the track using fancy data acquisition technology that takes into account
compliance in suspension components.
Gee, I just said that . Maybe I missed my calling ?
Well done Pete, for quoting sources, and shame on you Syd, as someone with a higher education, for not doing the same.
Another thing missing is the type of vehicle and the conditions under which it's being driven when you suggest equal length parallel control
arms. Designs that I've seen like that have virtually no roll and very little suspension movement.
Joel was asking about the locost design - solid axle rear, independent fronts with unequal a-arms, 3-6" wheel movement on what, a 50 or more?
year old design with no downforce at all. Modern race suspension design can't be directly applied to the Locost without some very careful
thinking. It's not relevant and it's not safe to make recommendations without specifying the design goals.
Many of us have done the 1/4" ply thing (or it's equivalent) to death. We know very well how the wheels respond geometrically. Sorry
Syd, but that post was completely useless in explaining what you're trying to say.
Another argument and this one is all Joel's fault
quote:
Originally posted by JoelP
thanks in advance for any comments (except comments of 'thick twat', these wont be appreciated...!)
|
|
|
James
|
| posted on 8/10/04 at 03:19 PM |
|
|
quote:
Originally posted by MikeP
Another argument and this one is all
I like to see it more as bringing together people from all over the globe!
Canada, US, UK and Australia all debating something- and people says the net's a bad thing!
James
[Edited on 8/10/04 by James]
|
|
|
Volvorsport
|
| posted on 8/10/04 at 03:56 PM |
|
|
well , if maclaren and such F1 teams still use roll centres well below ground level to give there drivers some feeling of roll weight transfer , and
making the car more driveable we shouldnt dismiss the idea of them .
And if we all use the mitchell software that uses forces to compute roll centres then well all get along .
|
|
|
splitrivet
|
| posted on 8/10/04 at 05:23 PM |
|
|
Ay up, I feel a twenty pager coming up now no biting or scratching of eyeballs ladies
Cheers,
Bob
I used to be a Werewolf but I'm alright nowwoooooooooooooo
|
|
|
Peteff
|
| posted on 8/10/04 at 07:36 PM |
|
|
tescos, that's where my roll centre is.
I have no idea where my roll centre is,
You'll make your mind up in a bit Steve. My wife's started baking ours, they're really good. We call them cobs round here though.
yours, Pete
I went into the RSPCA office the other day. It was so small you could hardly swing a cat in there.
|
|
|
pbura
|
| posted on 8/10/04 at 08:59 PM |
|
|
quote:
Originally posted by Syd BridgeAnd leave things at that.
Good enough, Syd! This was nowhere near as bloody as the bushing war
I enjoyed the debate, and felt like I learned a lot.
Pete
Pete
|
|
|
splitrivet
|
| posted on 8/10/04 at 09:09 PM |
|
|
quote:
Originally posted by Peteff
I have no idea where my roll centre is,
You'll make your mind up in a bit Steve. My wife's started baking ours, they're really good. We call them cobs round here though.
Aaaah yes,, a crusty cob with a big thick wedge of chayse an bunion(gotta be more interesting than this thread)
Cheers,
Bob
I used to be a Werewolf but I'm alright nowwoooooooooooooo
|
|
|
jcduroc
|
| posted on 22/10/04 at 12:34 AM |
|
|
quote:
Originally posted by Cita
The French word "ou" means nothing to me as i'm Flemish but i know the Flemish equivalent which is "of".
[Edited on 6/10/04 by Cita]
Come on!
You're not going to make me believe that an educated flemish like you doesn't speak a word of french!...
I guess you're "posing". We're not at Brussels...
JCM
|
|
|
