Lotus Elan

Elan +2 Steering

PostPost by: Hamish Coutts » Mon Feb 21, 2005 9:34 pm

Hello all.

I've owned a +2 S130 for just over a year. (and enjoyed every minute of it)
I'm used to 'modern' cars with fairly strong centering on the steering (loosen your grip on the wheel and the steering will return to centre lock)
What I've noticed with the elan is that there is no centering effect. The steering is neutral. Should this be the case? I've also noticed that there is little or no 'feedback' through the steering wheel.
I've overhauled the trunions, which seem free enough and the top ball joints are OK. Track rod ends also seem fine. There are no clunks or rattles coming from the steering when going over bumps.
The car has a spyder chassis and spyder front suspension. There are no other modifications.

Does anybody have any comments? Should the steering be a bit more lively?

Regards,

Hamish.

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PostPost by: john.p.clegg » Mon Feb 21, 2005 10:35 pm

Would this "centering steering" be on a front wheel drive car perhaps?
John
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PostPost by: Hamish Coutts » Tue Feb 22, 2005 8:33 am

John,

Doh! Have to confess that I'd never thought of that. Yes most of my experience has been in front wheel drive cars from a Cooper S in the late 60 through to today's cars with the exception of a Mk1 Lotus Cortina in the 70s.

That said though, should the Elan steering be so aparently neutral, 'dead' even, or am I just getting my knickers in a twist about nothing?

Regards,

Hamish.

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PostPost by: steveww » Tue Feb 22, 2005 9:17 am

I would have the tracking checked. I think you will find that the car is running toe out at the moment.
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PostPost by: rgh0 » Tue Feb 22, 2005 12:15 pm

Hamish

The self centering characteristics of the Elan and plus 2 is certainly less than most modern cars. I also find my plus 2 to be less than my elan though I am not sure why the longer suspension arms and wider track appear to give this characteristic. I also find that modern low profile sticky tyres reduce the self centre as well (eg dunlop 185x60x13 formula R on the plus 2).

The high steering ratio of the cars also means that self centre is less critical as you steer and point where you want it to go more than in ost modern cars.

However having said all of the above, I beleive you still be able to take your hands of the wheel as you accelerate out of a corner and have the wheel straighten itself up on a smooth and level road. If its not doing this I would start with a full alignment check to see if something is amiss.

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PostPost by: Hamish Coutts » Tue Feb 22, 2005 12:58 pm

Thanks Guys.

A quick visual inspection from the front of the car does seem to look like it is a tad toe out, though, the tyres (165/80/13s) don't show any sign of this.

I'll get it checked at the weekend.

Hamish.

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PostPost by: type26owner » Tue Feb 22, 2005 2:44 pm

Hamish,
The steering 'feel' is extremely important to a racecar driver. It's by far the one tactile feedback sense would which allow a driver to corner at the limit even if they were suddenly blinded. Many factors of the suspension design combine to give that sensation. The later cars were changed to a smaller castor angle and I believe this decreased the force of the feedback. Bet they did this as a marketing ploy to lure the weaker sex behind the wheel. Not much you can do to change that unless you're willing to do major surgery on the suspension geometry.

However. a large contributor to this feel is due to the torsional stiffness of the tire when deformed into the 'slip angle'. The pneumatic trail is the moment about which it exerts a restoring centering force. The restoring force is increased as the level of grip goes up sometimes. Run a hard, low grip, torsionally weak, junk tire like the Touring category and you'll get the least amount of feedback. You might try the RE92 and see if that helps any. It's a better, stiffer tire allround.

Here's some reading material. The first one has a picture which shows pneumatic trail.
<a href='http://www-cdr.stanford.edu/dynamic/forcefeedback/IMECE2004.pdf' target='_blank'>http://www-cdr.stanford.edu/dynamic/forcef...k/IMECE2004.pdf</a>
<a href='http://www.ozebiz.com.au/racetech/theory/align.html' target='_blank'>http://www.ozebiz.com.au/racetech/theory/align.html</a>
<a href='http://www.answers.com/topic/caster-angle' target='_blank'>http://www.answers.com/topic/caster-angle</a>
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PostPost by: Hamish Coutts » Tue Feb 22, 2005 9:41 pm

Keith,

Thanks for the info - a mine of information as ever.

So, if I fit a harder tyre (165/80/13) and check for toe out/in, should that solve the problem?

Also, is there any point in checking the steering rack to see, say, if it is getting stiff? If so do you know any tests that I can perform. (I'm not a qualified engineer, just a very keen, self taught grey haired amateur with long experience)

I fully agree with your comment on steering feedback. The only other feedback I value is that coming through your backside via the seat! I do love a lively car.
:D

Forgive me but I'm not familiar with an RE92. What make is it?

Thanks,

Hamish.
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PostPost by: type26owner » Tue Feb 22, 2005 10:54 pm

So, if I fit a harder tyre (165/80/13) and check for toe out/in, should that solve the problem?

Nope but do set the toe correctly. Two thumbtacks and a measuring tape is all takes and you're done in under five minutes if the toe is correct.

Also, is there any point in checking the steering rack to see, say, if it is getting stiff? If so do you know any tests that I can perform. (I'm not a qualified engineer, just a very keen, self taught grey haired amateur with long experience)

Fix any alignment or mechanical irregularities. The steering rack suffers from one major flaw. The pinion gear assembly also serves as the structural bushing for the rack on that end. As such the loads on the single tooth engagement wearout the rack's tooth at the straight ahead position resulting in a spring-loaded detent motion or binding feel. This should be corrected first before doing anything else. I've posted the repair info stuff either here or on the Yahoo list quite awhile back.


Forgive me but I'm not familiar with an RE92. What make is it?

Bridgestone Potenza RE92 P165/65R13
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PostPost by: mikefromengland » Thu Feb 24, 2005 9:51 pm

hello.i fitted new track rod ends a while ago.until the tracking was done it was like driving on ice.i had the tracking done and it was fine.the stering does center slightly but not like a modern car .it also depends on the camber of the road.get the tracking done keep you hands on the wheel at all times and give it some beens thats what i would do regards mike
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PostPost by: type26owner » Thu Feb 24, 2005 10:41 pm

The RE92 does change one other parameter which might just help the lack of centering on the 3 degree castor suspension. It's about 1.5" smaller in diameter than the original tire so that will change the scrub radius by some small amount. Hopefully by making it a bit larger. With the enhanced grip of this tire combined with a larger scrub radius that will tend to amplify the force for the steering to return to center. Not sure what the steering axis inclination so I can't make any sure fire promises though. Maybe the manual shows that info and it can be predicted better. Whatever it does it won't be by very much I'm guessing, certainly would not double the force for instance.

Running the wrong camber setting will also decrease the centering potentially. By far the biggest determinant is the lack of enough mechanical trail and castor normally.

You can always install a suicide knob on your girlie car. :P Just joking!
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