Doctor Derek Doctors
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| posted on 31/1/11 at 01:08 PM |
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BEC Bump and Droop for a Race Car
With my background being in the world of 1+ Ton Tin Top races I'm not experienced in suspension settings for BEC race cars.
Can anyone tell me roughly how much droop (if any) I should build into the suspension and how much movement I should realistically allow for in
bump?
This will be a rose-jointed RGB race car with no concessions for road use. Usually I'd start with Zero droop but like I said 7's are new
to me.
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kb58
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| posted on 31/1/11 at 03:14 PM |
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I'd go 1" droop and whatever's left over for compression. Because you didn't specify ride-height, wheel rates, and whether the
car has tunnels and wings, it's hard to be helpful.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Doctor Derek Doctors
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| posted on 31/1/11 at 03:30 PM |
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quote:
Originally posted by kb58
I'd go 1" droop and whatever's left over for compression. Because you didn't specify ride-height, wheel rates, and whether the
car has tunnels and wings, it's hard to be helpful.
Ride height will be as close to 75mm as I can get (RGB Min)
No Wings, maybe some minor ground effects but nothing significant (RGB is supposedly non-aero)
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kb58
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| posted on 31/1/11 at 04:06 PM |
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Then I'd vote for 25mm droop, 50mm compression, with an additional 12mm for a rubber bump-stop. This leaves out what your expected spring rates
are but I'm assuming you'd work that out in reverse off the expected track loads.
(I'm in the US so am unfamilar with your RGB series.)
[Edited on 1/31/11 by kb58]
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Doctor Derek Doctors
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| posted on 31/1/11 at 06:58 PM |
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Pretty much what I was thinking (50mm Bump) maybe a little more droop than I was expecting but then 1100KG Porsches are a whole other ball game.
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procomp
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| posted on 1/2/11 at 04:47 PM |
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Hi
1" is fine for front end but rear will require 1 1/2" obviously all dependent on your wheel to rod ratio.
Cheers Matt
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Doctor Derek Doctors
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| posted on 2/2/11 at 12:29 PM |
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quote:
Originally posted by procomp
Hi
1" is fine for front end but rear will require 1 1/2" obviously all dependent on your wheel to rod ratio.
Cheers Matt
The next question then (that I forgot to ask originally) is: What would be the target for the neutral camber settings? I.E when I build the car what
should the camber be (front and rear) when the camber adjusters are set to the mid point?
I was thinking around 2.5 degrees (front) and 1.5 degrees on the rear.
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kb58
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| posted on 2/2/11 at 02:29 PM |
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Depends on the type and width of the tires, as the wider they are the less camber change they can deal with. OTOH, some tires are made for just that
purpose, so it "depends." It also depends how the car's used. Drag-racing only, zero camber change. Tight road-race, a fair amount.
Long more open road-races, somewhere in the middle. That said, it all tends to even out, as one car will do better in on part of the track and another
car that's set up different will do better elsewhere, but the laptimes will be very close.
There won't be any black-and-white answers to this stuff.
[Edited on 2/2/11 by kb58]
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Doctor Derek Doctors
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| posted on 2/2/11 at 05:01 PM |
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quote:
Originally posted by kb58
Depends on the type and width of the tires, as the wider they are the less camber change they can deal with. OTOH, some tires are made for just that
purpose, so it "depends." It also depends how the car's used. Drag-racing only, zero camber change. Tight road-race, a fair amount.
Long more open road-races, somewhere in the middle. That said, it all tends to even out, as one car will do better in on part of the track and another
car that's set up different will do better elsewhere, but the laptimes will be very close.
There won't be any black-and-white answers to this stuff.
[Edited on 2/2/11 by kb58]
well that why I specifically asked for base target figures for a 7' competing in the RGB series.
Also you appear to have completely misunderstood the question and starting talking about camber change during suspension movement, which was not what
I was asking.
I am after the base figures for the camber when the camber adjusters are set in a central position. Although I apreciate that this will depend
somewhat on the amout of adjustment I have (which I will work out at the weekend).
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Ian-B
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| posted on 2/2/11 at 06:34 PM |
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My RGB car ran using slightly less droop and bump travel than is being quoted above, but that is with running wheel rates in the region of 2.7-2.9Hz
(this stiffness was not in order to reduce suspension travel).
The car ran approx 1.2 degree of camber, but this will vary dependant on your suspension geometry combined with roll stiffness and suspension system
stiffness.
Ian
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kb58
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| posted on 2/2/11 at 08:15 PM |
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quote:
Originally posted by Doctor Derek Doctors
...well that why I specifically asked for base target figures for a 7' competing in the RGB series. Also you appear to have completely
misunderstood the question and starting talking about camber change during suspension movement, which was not what I was asking...
Well how can anyone give answers to questions when large areas of your suspension design are unknowns? I included camber-gain as part of my answer
because, well, you didn't. Given that I don't know what you have, how can I possibly give anything more concrete than vague guidance,
since it's based upon vague information. I'm sorry you're disappointed I can't provide black-and-white answers, but
that's what you get when providing an enigma for a data set. About all you can hope for is that someone with an identical car pops in here and
is willing to share his secrets.
Mid-engine Locost - http://www.midlana.com
And the book - http://www.lulu.com/shop/kurt-bilinski/midlana/paperback/product-21330662.html
Kimini - a tube-frame, carbon shell, Honda Prelude VTEC mid-engine Mini: http://www.kimini.com
And its book -
http://www.lulu.com/shop/kurt-bilinski/kimini-how-to-design-and-build-a-mid-engine-sports-car-from-scratch/paperback/product-4858803.html
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Doctor Derek Doctors
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| posted on 2/2/11 at 08:26 PM |
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quote:
Originally posted by kb58
quote:
Originally posted by Doctor Derek Doctors
...well that why I specifically asked for base target figures for a 7' competing in the RGB series. Also you appear to have completely
misunderstood the question and starting talking about camber change during suspension movement, which was not what I was asking...
Well how can anyone give answers to questions when large areas of your suspension design are unknowns? I included camber-gain as part of my answer
because, well, you didn't. Given that I don't know what you have, how can I possibly give anything more concrete than vague guidance,
since it's based upon vague information. I'm sorry you're disappointed I can't provide black-and-white answers, but
that's what you get when providing an enigma for a data set. About all you can hope for is that someone with an identical car pops in here and
is willing to share his secrets.
Yawn.....
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Alan B
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| posted on 2/2/11 at 08:54 PM |
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quote:
Originally posted by Doctor Derek Doctors
quote:
Originally posted by kb58
quote:
Originally posted by Doctor Derek Doctors
...well that why I specifically asked for base target figures for a 7' competing in the RGB series. Also you appear to have completely
misunderstood the question and starting talking about camber change during suspension movement, which was not what I was asking...
Well how can anyone give answers to questions when large areas of your suspension design are unknowns? I included camber-gain as part of my answer
because, well, you didn't. Given that I don't know what you have, how can I possibly give anything more concrete than vague guidance,
since it's based upon vague information. I'm sorry you're disappointed I can't provide black-and-white answers, but
that's what you get when providing an enigma for a data set. About all you can hope for is that someone with an identical car pops in here and
is willing to share his secrets.
Yawn.....
Uncalled for and rude......not the best way to get help from someone....
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MikeFellows
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| posted on 2/2/11 at 09:03 PM |
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I've no idea what any of you are talking about
but it seems to me you had someone who did know what they were talking about and you pretty much told them to wee off. I cant image anyone's
cueing up to reply to you now.
[Edited on 2/2/11 by MikeFellows]
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daniel mason
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| posted on 2/2/11 at 09:09 PM |
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not the first time is it!
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Richard Quinn
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| posted on 2/2/11 at 09:37 PM |
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quote:
Originally posted by daniel mason
not the first time is it!
I've noticed a bit of a trend too. Have you tried asking your questions
HERE? Although, I would hazard a guess that
as your car is a one off, you will struggle to get anything more specific than given above. One of the joys of being at the cutting edge I'm
afraid.
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daniel mason
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| posted on 2/2/11 at 10:45 PM |
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how do you mean a one off? its standard mnr chassis! engine is slightly different though. was refering to op being rude. he said i couldn't read
the other day! lol
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Richard Quinn
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| posted on 2/2/11 at 11:02 PM |
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Sorry, I was agreeing with you that it wasn't the first time that there had been a response like that from the OP and that I'd noticed the
trend. The second part was aimed at pointing the OP in the direction of the RGB Forum and my comment about a one-off was regarding his chassis not
yours Daniel. Sorry, could've been clearer (it's been a long week already!)
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daniel mason
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| posted on 2/2/11 at 11:08 PM |
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no probs mate. have a beer and cheer up! lol
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Doctor Derek Doctors
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| posted on 3/2/11 at 12:49 PM |
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quote:
Originally posted by daniel mason
how do you mean a one off? its standard mnr chassis! engine is slightly different though. was refering to op being rude. he said i couldn't read
the other day! lol
Actually if you read that thread I was AGREEING with you and apologised and cleared up the misunderstanding.
As said it was a very simple question about were people running 7' race cars place their neutral camber position. Not in any way a question
about camber change in bump and roll.
On the other thread I pointed out that it wasn't an MNR and Mr Mason kindly pointed out were the chassis came from but then a load of people
failed to read any of the thread and started going round in circles.
I really don't understand why people feel the need to right a load of stuff without actually reading the original post or the existing answers.
Its the sort of 4Chan level banality that ruins forums.
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Richard Quinn
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| posted on 3/2/11 at 01:36 PM |
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quote:
Originally posted by Doctor Derek Doctors
quote:
were people running 7' race cars place their neutral camber position.
But would that not depend on how much camber your particular set up and chassis needs in the first place? If it's going to need about 2.5
degrees on the front to start with then this would be a good place for the adjustors to be centred around. If you think it will be between 2 and 3
degrees, centre it on 2.5 (assuming you can adjust by more than 0.5 either way). How much camber do you think you will be running and how much
adjustment do the adjustors give?
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