free hit
counters
mathmatical genius required.... - General Chat - The Lotus Forums Jump to content
Sign in to follow this  
910Esprit

mathmatical genius required....

Recommended Posts

I nicked this idea of the internet and even using a bit of architrave and manually holding against the wheel, I am getting consistent measurable results. So I am planning to refine the design and replace the architrave with an aluminium extrusion and introduce some sort of bungee to secure the device reliably to the wheel

The way it works is:

You project a laser (around

Share this post


Link to post
Share on other sites

Upgrade today to remove Google ads and support TLF.

You don't even need to work out the maths really.

Lotus specs are generally in distance rather than angle, so, move the axle stands forward by the rim size of your vehicle and the amount he dot moves in by is the toe in.

Even better, move it by a multiple of the rim size (say 17inch rims, move the wood by 85 inches), divide the distance the dots move in by that multiplier and it's easier to get a more precise measurement.

I would suggest you obtain 2 of those lasers, so that you don't have to disturb them while measuring both sides, nd of course make up 2 sets of clamping mechanisms.

You'd need a way to calibrate the set-up to determine parallel, but that should be quite simple by putting the 2 sets of wheel clamping bits with lases together and moving them away from a flat surface to ensure the 2 beams stay the same distance apart.

I tried reading this at work (might have been in an audio meeting at the time) and missed the bit about wood an axle stands, so couldn't work out the bit about moving axle stands.

Share this post


Link to post
Share on other sites

Bear in mind your readings will have to be very accurate for measuring toe. I don't know about an S3, but for an S4 the factory specs are:

Front: 1.0mm toe out overall +/- 0.5mm or 0.14 degress toe out overall +/- 0.07 degrees

Rear: 1.5mm in each side +/-0.5mm or 0.12 degrees toe in each side +/- 0.07'

Also, your method only measures the toe relative to the other wheels, not to the centre line of the car, i.e. you could have all four wheels off by the same amount, not pointing in the direction of the centre line of the car without realising.


May: DON'T hit it with a hammer!

Clarkson: Why?

May: Cause it's the tool of a pikey.

Share this post


Link to post
Share on other sites

For the front there is no real difference other than the steering rack might be slightly out of centre.

For the rears, as Neal states. That would result in the thrust line being out and the car crabs slightly.

Then there's camber on both front & rear and caster on just the front.

However for purely toe on the front it's fine.

Share this post


Link to post
Share on other sites

Thanks for your input guys. I think I've got in now - As long as I use multiples of wheel diameter between the 2 measurement points there is no relationship with the actual distance from the car - as the angle being measured is always consistent.

Yep, I am purely using this method for front toe. I know the steering wheel is correctly centred, so that reasonably indicates the centre line. The very fact that you can amplify the result suggests to me that I will be able to get a very good level of accuracy. One further test I am going to do is run a dial gauge around both wheel rims so I can use an avarage figure to account for any slight distortion.

cheers Steve

Share this post


Link to post
Share on other sites

What the NASCAR boys use is two pieces of flat aluminium plate with a notch at the front and the rear both about 2 inches from the bottom. The plates also have a cut out about 3 inches tall and 7 inches long. They place the plates one against each front tyre so the cut out is over the tyre bulge. Your helper then passes a tape rule under the car at the back of the wheel and you hook it into the rear notch and he does likewise and noted the distance. You both then do the same in front of the wheel and calculate the difference to give the toe-in or out.


S4 Elan, Elan +2S, Federal-spec, World Championship Edition S2 Esprit #42, S1 Elise, Excel SE

 

Share this post


Link to post
Share on other sites
I don't know about an S3, but for an S4 the factory specs are:

Front: 1.0mm toe out overall +/- 0.5mm or 0.14 degress toe out overall +/- 0.07 degrees

Rear: 1.5mm in each side +/-0.5mm or 0.12 degrees toe in each side +/- 0.07'

I don't have my owner's manual handy at the moment, Neal, but regardless of the actual mm numbers for my (and your) V8 I do recall my astonishment at seeing a "toe out" specified for the front wheels/tires. I thought it was a "typo" at first, as all my previous vehicles had "toe in" at the front. And I see that you show the same setup (toe out) on the S4. Is this how Colin's designs achieved their incredible reputation for cornering capabilities? And if so, do more mundane vehicles have toe in up front solely for "straightline" tire wear issues? What gives?

Are all Esprits this way? How 'bout Loti in general?

Regards,

John

p.s., 10 quid 5 newpence says Bibs has this thread moved to "General Motoring" by sundown tomorrow. :scared:

Edited by Iconic Ride

Being second is to be the first of the ones who lose.

Share this post


Link to post
Share on other sites
I don't have my owner's manual handy at the moment, Neal, but regardless of the actual mm numbers for my (and your) V8 I do recall my astonishment at seeing a "toe out" specified for the front wheels/tires. I thought it was a "typo" at first, as all my previous vehicles had "toe in" at the front. And I see that you show the same setup (toe out) on the S4. Is this how Colin's designs achieved their incredible reputation for cornering capabilities? And if so, do more mundane vehicles have toe in up front solely for "straightline" tire wear issues? What gives?

In general front toe in causes stability and initial understeer in a turn. Front toe out causes instability and initial oversteer.

So basically the Esprit is intentially set up with a front toe out to give it better turn in and a more 'sporty' steering than your everyday car.

But it's only a small amount - 0.14' total, otherwise the steering would become too twitchy and the car too tail happy.


May: DON'T hit it with a hammer!

Clarkson: Why?

May: Cause it's the tool of a pikey.

Share this post


Link to post
Share on other sites

Thanks for the response, Neal. Upon reflection, that makes sense.

I suppose an aviation analogy would be later generation fighters (F16 and up) being purposely designed to be unstable so as to enhance maneuverability ("quick turn in," literally---it's said that the F16, and most current NASA prototypes, are "unflyable" without the flight control computers on [3 on the F16, and they "vote" if one in in disagreement], and that the control surfaces are making many inputs per second).

Regards,

John


Being second is to be the first of the ones who lose.

Share this post


Link to post
Share on other sites

The 'inherently unstable' F104 Starfighter. A missile with wings, little ones at that and a bloke up front in a spacesuit!

300px-F-104_right_side_view.jpg


88 Esprit NA, 89 Esprit Turbo SE, Evora, Evora S, Evora IPS, Evora S IPS, Evora S IPS SR, Evora 400, Elise S1, Elise S1 111s, Evora GT410 Sport

Evora NA

For forum issues, please contact the Moderators. I will aim to respond to emails/PM's Mon-Fri 9-6 GMT. 

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

×
×
  • Create New...