Toe-out

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Toe-out

Postby Bern » Thu 28.07.2016, 22:24

Hi All,

I'm just checking the wheel alignment sheet that I got from F1 autocentres when I had the geometry checked.

My car now has a toe value of -0.5 (which I assume is toe-out, and in mm rather than degrees) on both wheels, and a total Toe of -0.9!

I've found an Elan service sheet on the net which says that the toe-out should be 0 to 0.25 degrees. But of course I can't compare the mm I have to the degrees on the sheet.

Does this sound excessive? Before the adjustment it was on 0.6 and 0.7, so they've brought it in a bit, but it still doesn't feel right to me.

The caster and camber seem to be within the specified values, though maybe the rear camber isn't quite enough (I've got -0.15 and -0.1, the service sheet says -0.05 +- 0.25), but not sure if that'll make much of a difference.

If the toe-out is in mm, is this usually measured at the outer edge of the tyre? I can convert degrees to mm using pi (who knew that'd ever come in handy??).

Cheers,

Bern.
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Re: Toe-out

Postby Bern » Thu 28.07.2016, 22:36

205 50 R15 tyres

Diameter of wheel = 381mm

Diameter of tyre = 381 + ((205 x 50%) x 2) = 586

Radius of tyre = 586 / 2 = 293

Therefore Circumference (2 pi r) = 1840.97

1 degree = 1840.97 / 360 = 5.113mm

0.25 degree = 1.27mm

So according to that I'm within tolerance! Provided I've worked it out correctly of course!

(the car isn't here, otherwise Id' just measure the diameter of the tyre!!)
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Re: Toe-out

Postby dapinky » Thu 28.07.2016, 22:49

Bern,

Just checking on my suspension setting sheet (copy attached for reference if you want/need it) - I have got 1/4 degree listed as 1.66mm, but I can't recall how or where I got that figure from (it was a while ago, and involved geometry - that much I remember). I know i took measurements for the 1.66mm from the centre line of the wheel (ie, the forward and rearward most points

suspension settings.pdf
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Re: Toe-out

Postby lotusflasherman » Thu 28.07.2016, 23:46

Bern wrote:Hi All,

If the toe-out is in mm, is this usually measured at the outer edge of the tyre? I can convert degrees to mm using pi (who knew that'd ever come in handy??).

Cheers,

Bern.


It's usually measured on the outermost rim of the wheel at axle height which is why they quote 0° to 0.25° toe out, rather than mm. Different diameter wheels would give different mm for the same angle and tyres can have embossed writing just where you don't need it so it's not a good idea to try to measure anything off a tyre.

I read Dave's sheet with interest... just wondering where he finds a 75kg (11 3/4 stone) driver .. :lol:
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Re: Toe-out

Postby lotusflasherman » Fri 29.07.2016, 00:14

dapinky wrote:Bern,

Just checking on my suspension setting sheet (copy attached for reference if you want/need it) - I have got 1/4 degree listed as 1.66mm, but I can't recall how or where I got that figure from (it was a while ago, and involved geometry - that much I remember). I know i took measurements for the 1.66mm from the centre line of the wheel (ie, the forward and rearward most points

suspension settings.pdf


Just been doing a bit of trigonmetry Dave. Tan of 0.25° is .00436 and 1.66/.00436 gives 380.73 mm as the distance between your points of measurement. Seems to agree nicely with Bern's calculation for wheel diameter of 381 mm
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Re: Toe-out

Postby lotusflasherman » Fri 29.07.2016, 01:04

Bern wrote:Hi All,

I'm just checking the wheel alignment sheet that I got from F1 autocentres when I had the geometry checked.

My car now has a toe value of -0.5 (which I assume is toe-out, and in mm rather than degrees) on both wheels, and a total Toe of -0.9!

I've found an Elan service sheet on the net which says that the toe-out should be 0 to 0.25 degrees. But of course I can't compare the mm I have to the degrees on the sheet.

Does this sound excessive? Before the adjustment it was on 0.6 and 0.7, so they've brought it in a bit, but it still doesn't feel right to me.

The caster and camber seem to be within the specified values, though maybe the rear camber isn't quite enough (I've got -0.15 and -0.1, the service sheet says -0.05 +- 0.25), but not sure if that'll make much of a difference.

If the toe-out is in mm, is this usually measured at the outer edge of the tyre? I can convert degrees to mm using pi (who knew that'd ever come in handy??).

Cheers,

Bern.


Bern,

see you say it still doesn't feel right - front should, to all intents and purposes, be parallel, i.e 0°, or just a little bit, 0.25°, of toe out if it can't set at exactly 0°. You don't mention what the rear set up is which is crucial.

The rears should TOE IN by 1. 5mm to 2.0 mm each side, which is at least 0.25° of Toe IN and this gives stability. Too much Toe In wears tyres but Toe Out on the rear will give you a 'wandering rear end' and a 'vague feel'. This is because as one rear wheel unweights, the loaded other rear wheel steers outwards turning the car slightly, and then when the first wheel is loaded again it pulls it back, or worse, when the other wheel unweights, it will steer it the other way. It's all very subtle but a Lotus should feel 'painted on the road' and not feel like it's skipping about like an MX5 ...
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Re: Toe-out

Postby Bern » Fri 29.07.2016, 08:41

Thanks chaps, much appreciated.

The toe-in on the rear is +1.8 and +1.9, so that appears to be correct :-)

The rear camber is -0°15' and -0°10'.

My spec sheet, and Dave's too, says -0.5° +/- 0.25° for the rear camber. I think I'm correct in saying that 0.25° = 15'.

So the rear camber should be between -0°15' and -0°45'. This means that one of mine is out, but not by much!

It's interesting that you mention the MX5, I had 2 of them. A mk2 which was actually quite nice, and a mk3 which was an awful car. Well, it wasn't an awful car really, but it wasn't a sports car. I was expecting the Elan to be better than both of them, and from a "character" point of view that's definitely true, but in terms of handling I felt safer in both MX5s. And the MG B. In fact even my van felt more predictable.

Or maybe it's just me! Could I get a volunteer to drive my car and see what they think? This is the only Elan I've ever driven and maybe there is nothing wrong with it.

Cheers,

Bern.

(Incidentally I'm less than 75kg, just ;-) )
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Re: Toe-out

Postby dapinky » Fri 29.07.2016, 09:38

lotusflasherman wrote:I read Dave's sheet with interest... just wondering where he finds a 75kg (11 3/4 stone) driver .. :lol:


I simply placed 3 x 25Kg bags of sand in the car - it was the only way i could replicate the numbers - - but then I thought about it and decided that there was little point in setting it up for a situation which wouldn't exist in practice, and checked the numbers with 110Kg in the car - apart from a slightly lower ride height (only 1.2mm) and a small change in castor (well within the printed limits), the rest remained unchanged.
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Re: Toe-out

Postby Artaban » Fri 29.07.2016, 10:35

Bern,
I'm down in Gillingham (about 25 miles away) so if you want to meet up and drive mine and I drive yours and then we can compare notes. I've had the advantage of a complete suspension rebuild last year with all new bushes, dampers and springs and SJ's have just set up the dampers. It still needs a few tweaks to the castor settings and that will be done when Ross at SJ's is back from hols. However once thats done it should be as it left the factory. Like you my car is the only M100 I've driven so I'd be interested to know how they differ. I will say though that when the car is right it feels really planted so if its makes you nervous then something must be out.
My car was also set up with 75kg of weights. I don't think I've been 75 kg since I was 14 but then my school was obsessed with rugby. I'm pleased to know that 110kg (my weight) is not an issue with ride height.
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Re: Toe-out

Postby Bern » Fri 29.07.2016, 10:57

I'd imagine that they didn't have any weight in my car when they took those settings, but you suggest that it wouldn't make much difference.

The value of -0.5 I have for the toe-out is less than Dave's 1.66 and my 1.27 so it ought to be good I guess :-(

I've had new tyres fitted, and probably been about 120 miles with them.

I had the tyres at 27 psi, and it didn't feel vague, but did feel a bit oversteery on corners, but not in a nice way!

I then put them down to 26 psi and then it did feel vague! I only drove it a short distance on 26 so can't comment on the oversteer, it was all in a 30 limit so didn't push it through the corners. Would 1 psi really make that difference?

The vagueness was there before the new tyres, so it was nice that it went away. Maybe it's the newness of the tyres that is giving me the oversteer, and maybe that will go away as they wear in!?

Or I'm wondering if maybe it's the brakes, they sometimes feel unbalanced, so I'm wondering if sometimes one sticks and pulls the car in that direction? The car had not been used very much prior to me getting it. I've cleaned the brakes, the pistons appear to move in and out ok, I was hoping that with use they'd get better. There does seem to be a bit of slack in the sliders on the calipers.
Last edited by Bern on Fri 29.07.2016, 11:41, edited 1 time in total.
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Re: Toe-out

Postby Bern » Fri 29.07.2016, 11:02

Hi Andy,

Thanks for the offer, that sounds like a great idea.

We could meet half way, perhaps Bruton or Castle Cary?

Cheers,

Bern.
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Re: Toe-out

Postby rip » Fri 29.07.2016, 11:25

lotusflasherman wrote:I read Dave's sheet with interest... just wondering where he finds a 75kg (11 3/4 stone) driver .. :lol:

My Elan has a 11 1/2 stone driver. :-D
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Re: Toe-out

Postby lotusflasherman » Fri 29.07.2016, 11:39

Bern wrote:Thanks chaps, much appreciated.

The toe-in on the rear is +1.8 and +1.9, so that appears to be correct :-)

The rear camber is -0°15' and -0°10'.

My spec sheet, and Dave's too, says -0.5° +/- 0.25° for the rear camber. I think I'm correct in saying that 0.25° = 15'.

So the rear camber should be between -0°15' and -0°45'. This means that one of mine is out, but not by much!

It's interesting that you mention the MX5, I had 2 of them. A mk2 which was actually quite nice, and a mk3 which was an awful car. Well, it wasn't an awful car really, but it wasn't a sports car. I was expecting the Elan to be better than both of them, and from a "character" point of view that's definitely true, but in terms of handling I felt safer in both MX5s. And the MG B. In fact even my van felt more predictable.

Or maybe it's just me! Could I get a volunteer to drive my car and see what they think? This is the only Elan I've ever driven and maybe there is nothing wrong with it.

Cheers,

Bern.

(Incidentally I'm less than 75kg, just ;-) )


I'm slightly the wrong side of 12 stone so I've just found a good reason to loose that 1/2 stone, or more, that I don't need ... :D

Sounds like the geometry is about right. What tyre pressures are you using? Should be 26 / 27 psi or thereabouts. I'm sure Dave would give you his expert opinion as he's not too far away, perhaps at the next 'get together'. .. :poke:

If the tyres are at the right pressure and moving at the right angles the only thing left is dampers - no sign of any oil leaks are there?

I worked on a long term contract near Horncastle with a guy who had an early 1.8 MX5 with 5 speed box (whatever model that was). We had to work August Bank Holiday Monday but had completed before lunchtime so Site Manager said 'bugger off'... I didn't want to go back to hotel so said I was going to watch Superbikes at nearby Cadwell Park and set off in M100 with MX5 guy following across the Lincolnshire Wolds. He reckoned I'd been cruising through the bumpy corners (correct) while he'd felt 'on the ragged edge'. On return journey I followed him and thought nearside rear wheel looked 'a bit lively' and he found that damper wasn't doing much so bought a new pair for the rear. He said it was much better but when I drove it I wasn't very impressed. Thought it wasn't going to be like a 'baby Elan' but more like a Frogeye Sprite I bought for my girlfriend in the '70's - fun but still a bit vague about where it's going on bumpy and undulating roads. Never felt stuck to the road like an Elan.

Update ... got phone call when typing the above and see you've now answered some of that. Tyre pressures are not that crucial that 1 psi would change how it feels. Pressures alter when tyres warm up and when atmospheric pressure changes.
Last edited by lotusflasherman on Fri 29.07.2016, 11:47, edited 1 time in total.
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Re: Toe-out

Postby Artaban » Fri 29.07.2016, 11:40

Bern,
We could meet at The Natterjack Inn, Evercreech on the A371 and then drive the 6 miles into Bruton and compare notes. My car won't have been tweaked until the middle/end of August and the only time I have before I go on holiday is this weekend or next Tuesday. I'm happy to meet up before SJ's tweak mine if you want an opinion on your car (you can still drive mine) or wait until later in August. I'll leave it up to you.
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Re: Toe-out

Postby Bern » Fri 29.07.2016, 12:08

Phil - the dampers I think are ok, I've certainly no issues with the ride quality at all, very impressed actually. And yes, I've tried 26 and 27 psi on the tyres.

And it sounds like I'm right in expecting it to be much better than an MX5!

Andy - I know the Natterjack, though I've never been in it!

I'm supposed to be doing some building work this weekend, but it'd be good to have an excuse to get away from it for a bit :-)

Or I can do Tuesday evening, but not the day.

So whenever is best for you really (though Saturday is probably a better day then Sunday for me)!!!

Cheers,

Bern.
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Re: Toe-out

Postby Artaban » Fri 29.07.2016, 13:23

Bern,
Lets see how the weather goes. Its not that I'm precious about the car but I can't put the top up until after Monday as I've had the rear deck re-sprayed and on Monday its having a clear 3m film wrap on it so that the rear hood seal doesn't pull the paint off. Tuesday evening may be better and probably a bit quieter on the roads than the weekend. I'll PM my contact details. Enjoy the building work.
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Re: Toe-out

Postby Bern » Fri 29.07.2016, 14:00

Hi Andy,

That's all fine with me.

I'll take the Elan up to the office again on Monday (a 100 mile round trip) and see if that helps the tyres bed in.

Hopefully it will be a better car for Tuesday!

I've just been looking at SJ Sportscar's website, and they have worked on it before (I have the receipts), maybe I should get them to take a look at the bushes, dampers and springs.

Cheers,

Bern.
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Re: Toe-out

Postby Bern » Sat 06.08.2016, 12:03

An update!

I've just checked the bushes for wear/play, as best I can, and it looks like the top front wishbone bushes are a bit soft, especially on the drivers side.

Also the top ball joint looks to be at an odd angle, I'll try and get a photo of that!

I guess that as long as the nuts undo this isn't too difficult a job, though it looks like it might be better to use a press on the bushes rather than my usual socket and lump hammer method!

Cheers,

Bern.
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