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Some questions (Control Arms, Shifter Arm, Hub)
Clay - 5/5/05 at 01:58 AM

I am new to locost building, but i am a Mechanical Engineering student with a basic education in chassis engineering. I've read Tune to win, and Engineer to win by Carroll Smith, Chassis Engineering by Herb Adams, and Build your own sports car 2nd edition by Ron Champion.

Here are some questions:

When using double wishbone A-arms can you make them un-cemetrical? Like, can one arm of the A-arm be longer than the other, or be at an offset angle? For packaging purposes?

Also, can some of you post your fixes for remote shifters? Ive seen a couple but would like to see some other fixes for shifter placement.

What spindles/hubs do the americans use since we dont have cortinas(spelling?) available?

And lastly, those of you who have photos of the progress of their build, can you please post them? Ive seen one or two photo diaries of their locost builds, but you can never see enough.

thanks

want2race - 5/5/05 at 02:38 AM

Firstly the fact you have a degree in that and dont know the answers leaves me fearing American engineering!

Secondly your options are limitless. go to yahoogroups and look for locost there is a massive listing of posts by various people.. all your answers are there!

www.want2race.net/lotus7/building

[Edited on 5/5/05 by want2race]

kb58 - 5/5/05 at 05:22 AM

You need to read a few more books! Check out my list, here: http://www.kimini.com/Reference/index.html

If none other, read Staniforth's "Competition Car Suspension"

Also check out my site and other's for build pictures. I have a few remote shifter pictures buried in there somewhere... just go back a few years.

Clay - 5/5/05 at 06:19 AM

quote:
Originally posted by want2race
Firstly the fact you have a degree in that and dont know the answers leaves me fearing American engineering!

[Edited on 5/5/05 by want2race]


I am a second year college engineering student. So that means I havent started any classes directly related to my major yet. American Engineering doesnt have a problem, i just havent gotten into the core of my education yet. The education in chassis engineering i mentioned is from reading chassis engineering books, not from school. But either way, I dont and wont have any classes that discuss control arm design or popular kit car spindles.

quote:
Originally posted by kb58
You need to read a few more books! Check out my list, here: http://www.kimini.com/Reference/index.html

If none other, read Staniforth's "Competition Car Suspension"

Also check out my site and other's for build pictures. I have a few remote shifter pictures buried in there somewhere... just go back a few years.


kb58, thank you! im always excited about reading new books on chassis engineering and furthering my knowledge. Ive recently purchased a "How to build hot rod chassis" book that arrives tomorrow, It may help with some explanation. ill check out your reccomendations also, i appreciate your advice and pictures.


[Edited on 5/5/05 by Clay]

Clay - 5/5/05 at 08:30 AM

want2race, i saw the picture of the miata, was that the donor car you used? Are the spindles/hubs on your locost from the miata?

chrisf - 5/5/05 at 09:55 AM

Unequal length A arms are used quite a bit. The lower arm will be the longer. This is well described in 'Tune to Win.'

I might be a bit biased, but the Miata is the best of the US donors. Quite a few people use them and you may not have to design anything at all. It may be done for you!

Have a look at my website for a build diary. I'm using Miata bits and a bike engine.

--HTH, Chris

James - 5/5/05 at 10:31 AM

quote:
Originally posted by Clay

When using double wishbone A-arms can you make them un-cemetrical? Like, can one arm of the A-arm be longer than the other, or be at an offset angle? For packaging purposes?

And lastly, those of you who have photos of the progress of their build, can you please post them? Ive seen one or two photo diaries of their locost builds, but you can never see enough.

thanks


Hi Clay,

Welcome to the site.

The arms of a wishbone can be different lengths- I pretty sure I've seen Formula 1 cars with different length arms.

As for build progress: have a look through the photo archives here. Loads of people have comprehensie archives.

Hope that helps,
James

Alan B - 5/5/05 at 12:00 PM

Hey Clay...where in Florida?

We could be neighbors.....

Also check out my site too...click www below....

Welcome to the site.

Alan

NS Dev - 5/5/05 at 01:18 PM

welcome, for a start!

suspension arms can be pretty much any shape, size or anything else.

As long as you remember the basic engineering that you are learning now, and apply it, then you have no problem.

Certainly unequal length top and bottom A-arms are critical to handling characteristics, all the locosts on here have unequal length arms, those using sierra uprights perhaps too much so!

Obviously, a shorter upper arm will pull the "top" of the wheel in during roll, and induce more negative camber, thus compensating for the tyres rolling over on the rim during cornering.

the arms can also be angled convergent or divergent relative to each other, and this then affects the roll centre, which in turn dramatically affects the handling (roll centre vs COG)

The arms can then also be angled fore and aft, which then brings in many complex equations regarding castor angle change in roll, some of which I have incorporated into the skewed suspension setup on my short oval grasstracker, but won't go into the complications of now!

Clay - 5/5/05 at 06:03 PM

I apologize, I should have made my question more clear. I am fully aware of the effects of unequal length A arms and changing their angles. My question was about the shape of each arm. A symetric A-Arm would be an isosceles triangle, with both legs of the arm being the same length. Ive seen some people that have odd shaped control arms. They are still shaped like an A but each leg is a different length to fit under a shell or fit around a mid engine, etc. I was wondering if changing the shape from an isosceles triangle had any adverse effects. My line of thought is that as long as it follows the same arc of travel, it should be fine. but i was looking for some assurance.


quote:
Originally posted by Alan B
Hey Clay...where in Florida?

We could be neighbors.....

Also check out my site too...click www below....

Welcome to the site.

Alan


Hey Alan, Im in Orlando, how bout you? Thanks for the welcome.

quote:
Originally posted by chrisf
Unequal length A arms are used quite a bit. The lower arm will be the longer. This is well described in 'Tune to Win.'

I might be a bit biased, but the Miata is the best of the US donors. Quite a few people use them and you may not have to design anything at all. It may be done for you!

Have a look at my website for a build diary. I'm using Miata bits and a bike engine.

--HTH, Chris


I was also thinking the same thing about the miata being golden in this type of project after seeing some pictures. thanks for the link to your build diary, im sure ill be posting some questions for you shortly.

Thanks everyone for the friendly welcomes, im sure this will become more of an unhealthy obsession as my knowledge builds from the help of you all :-)

clbarclay - 5/5/05 at 06:23 PM

I shouldn't think wishbones not being isosceles makes any difference.

I would guess that the majority of wishbones are not isosceles, the only example of isosceles wishbones I can think of is locost lower wishbones (mabye seen one or two others but can't remeder them at the moment), the top locost ones are not isosceles



[Edited on 5/5/05 by clbarclay]

Clay - 5/5/05 at 11:28 PM

want2race, did you have to alter the location of your shifter or did it line up to a decent location in relation to your body sitting in the car?

want2race - 6/5/05 at 02:23 AM

Hit me up on AIM.
my sn is eyedhitit

I moved the engine back till I got what I wanted! And my chassis is EXACTLY what I wanted in all cases No exceptions just solutions~