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Tramlining - caster question


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My '89 SE has always tramlined badly.  On uneven roads (loads here in NZ) the car gets pulled around something shocking.  Even on flat roads the car needs to be steered constantly.  A few weeks after I got the car (Jan '20) I had a wheel alignment done.  It didn't seem to make any difference to the tramlining.  Results of caster adjustment were (before correction, Min, Target, Max, after correction): Left  +00deg 23 min,  +01deg 0 min,  +01deg 15min, +01deg 30min,  +00deg 19min.   Right  +00deg 01min,  +01deg 00min,  +01deg 15min,  +01deg 30min,  -00deg 01min.  Hope this makes sense.  Essentially, the "after correction" caster values are still outside minima and maxima.  If anyone can interpret them and advise whether these values would be more likely to cause the tramlining, it would be appreciated.  I had decided to just live with it but after a long trip away last weekend, it bugged me too much.  Full report attached.

Esprit_Align.jpeg

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Someone more expert than me will probably be along soon to give a better opinion, but for what it's worth here is mine.

Caster is far less than optimum and that will make tramlining worse. The figures I have for the low wing SE are 1 deg caster, you have almost zero. In fact they have adjusted it -ve on the right wheel which is terrible.

Toe is way too much at 4mm, should be max 1.9mm overall.

But to me the most worrying is the +ve camber on the left wheel. That indicates damage, wear on bushes normally gives more -ve not less. I suspect a bent bottom arm.

Certainly the front needs a careful look at and realignment by someone that knows what they are doing, which does not appear to be the people you went to,

On the plus side the rear doesn't seem bad. 

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Irrespective of whether it will reduce tramlining or not, Lotus set the suspension up for maximum handling performance so what's the point of owning a performance car that can't perform because it's not set up correctly? 

Cheers,

John W

http://jonwatkins.co.uk

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Some of the 'specification' values in that print out are not correct (be aware there are two different values for the front geometry on the '88 - '92 vehicles). Before attempting to get it re-aligned I would check that the shims are correctly installed first, it is very common to find the number fitted or position is incorrect.

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Thanks for the input guys.

It's a bit of a mission finding competent specialists here in the backwoods of NZ.  It's almost good to know that you think that some of the alignment values are way out.  It gives me hope that the steering issues are fixable.  Mine is the only Esprit I've ever driven so I was unsure what they are supposed to feel like.  I'm confident the car has not had a shunt.  Bodywork is totally original.

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Even if it's not been in a shunt something very funny has happened to your left front.

Under most load conditions the top wishbone arms are in compression, so as bushes wear/deform, the top of the vertical link moves inwards. The bottom arms are in tension, so as bushes wear/deform, the bottom of the vertical link moves outwards. Either/both of these increase -ve camber.

To get positive camber either the top wishbone has got longer, which is very difficult to do with a fixed length wishbone! or the bottom arm has got shorter which is easily done if it is bent. It doesn't have to be impact damage, something as simple as jacking up the car on the link rather than using a jacking point can do it.

Half a deg -ve on one side and quarter deg +ve on the other will make any car handle strangely.

The above assumes the wheel isn't buckled, if it is then any suspension measurements are almost meaningless.

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  • 3 weeks later...

Terry,

You may try to call Possum Bourne Motorsports for advice and/or service.

Phone: 09 238 5732

They are very competent when it comes to Exotic/racing cars.

https://www.possumbournemotorsport.com/services/

Edited by MrDangerUS
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  • 3 weeks later...
On 26/03/2021 at 06:08, MrDangerUS said:

Terry,

You may try to call Possum Bourne Motorsports for advice and/or service.

Phone: 09 238 5732

They are very competent when it comes to Exotic/racing cars.

https://www.possumbournemotorsport.com/services/

Thanks John.

I hope to avoid having to taking the car to the big smoke (Auckland).  It's about 6 hours away but I'll definitely give these guys a call.

Cheers.

On 05/03/2021 at 09:56, TheKevlarKid said:

Tyres can cause bad tramlining. 

How old are they, what brand? Not Pirelli by any chance?

Dunlops, directional, about 80% tread and wearing evenly from what I can see.

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  • 2 weeks later...
On 04/03/2021 at 11:25, sailorbob said:

Some of the 'specification' values in that print out are not correct (be aware there are two different values for the front geometry on the '88 - '92 vehicles). Before attempting to get it re-aligned I would check that the shims are correctly installed first, it is very common to find the number fitted or position is incorrect.

I second that. Mine was incorrectly installed, and tramlined badly. After I took it all apart. All. I noticed that it was not correctly installed with shims etc. Then I installed as per procedure and I chose my own mix of SE, V8 and Sport300, because of wheels, tires etc, it steers very well, no problems.

So, start with fresh bushings and inspect the arms that some people sometimes think they can lift the car on... And they often misinterpretate the installation of shims, hence they sit incorrectly.

And btw. you can do a full geo yourself. Take your time, use a string and 4 stands, a ruler, a few thin plastic floor pieces to level the car with if need be, a pencil and a roll of painters tape, and angle measurement, or camber thingy, and a level floor. It takes some hours and a pot of tea, but then it's not that hard ;) And you'll thank yourself. I did it myself last year, and the car never drove so well, as after that work. Well worth your time and effort.

Have a set of shims for the front and rear ready beforehand. They come in stainless nowadays, if one so cares for.

Kind regards,

Jacques

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Nobody does it better - than Lotus ;)

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Note to self:

If you so it yourself, Lotus uprated Lotac bushing programme: the radius arm bushing went from 7/16" to 12mm diameter through stud, and therefore need the other stud, nuts etc. And then you need to drill the tube inside the radius arm up to spec.

Btw. the bracket that sit around the radius arm front mount shim-plates, also exists in stainless if one so cares.

It's a little bit tedious to change it all, but then it's fresh and you can actually depend on what you measure and adjust to, rather than old worn bushings. Some people seem to use new 12mm bushing with old thinner stud, and that would not be a good idea...

Kind regards,

Jacques

Nobody does it better - than Lotus ;)

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