Setting up the suspension geometry - Midlands

[gturner008]

I guess my car has not had the suspension adjusted for some considerable time (I guess at least 10 years). Despite low miles travelled in last 30 years (5k miles!), I would like to give the suspension a good check and re-set geometry.

My question is - should I do this? Does anyone recommend somewhere in the Midlands to do this?

Also - I noticed the steering wheel does not 'centre' when driving along and turn the wheel. I have to manually bring the wheel back to centre. I don't think this is correct. I would expect the wheel to centre on its own. Hopefully this is something that can be adjusted (camber, castor, toe in etc). I'd like to do all the adjustments in one go. Any advice?

[jbcollier]

Any good alignment shop can do the work.  Only toe is adjustable front and rear.  You can get adjustable lower arms for the rear so you can also adjust the camber (good idea).  Banks and the other usual suspects sell them.

The steering is usually not self-centering on a Europa.  I believe very careful work on the steering column and rack can help somewhat (internal stiction).

[EuropaTC]

Hi Gary,

Unless your car has some fancy upper wishbones, the only geometry adjustments at the front will be toe-in, and that's basic stuff on the track rod ends. Nothing complex, any garage should be fine with that.

The rear is more complex. Again, unless you have the adjustable lower links on the car you are restricted to toe-in adjustments at the rear wheels, but this is much more of a hassle. Adjustment is by shims between the chassis and the radius arm, and that doesn't come under the remit of your average Kwik-Fit fitter, so be prepared for puzzled looks ! 

Having recently gone through this I would recommend either you do it yourself or a specialist who is prepared to take time over the job, and preferably one who deals in classic Lotus.  There are probably many in your area, the nearest "famous" one that comes to mind is Paul Matty's although that's a drive away ?

It's not a technically hard task, just time consuming for DIY, although I sort of like these challenges even if I struggle at times.  Here's the thread from when I did mine and got confused/puzzled with my readings....  http://www.lotuseuropa.org/LotusForum/index.php?topic=850.0

Brian

[ron parola]

Also be aware the steering rack does have a mechanical dampener built in. It is designed to dampen road shocks through the steering wheel, they are adjustable via either nut adjustment or shims, I don't recall which. And the racks do need to be lubed on occasion also, my car does have some self centering but it's not great. The cars have almost no caster and it's not really adjustable but if the rear of the car is too high remember that will lessen the caster angle. ronp

[BDA]

Hi Ron,

I'm not aware of any mechanical dampeners in the steering rack. I took mine apart a long time ago and as I remember, it wasn't much more than a rack and pinion. The pinion to rack lash was adjusted with shims. Could that be what you're thinking about? The tie rod attachment to the rack is adjusted with shims also but my understanding is that neither of these performs any damping function. It's a Spitfire rack that is adapted for the Europa.

There could be some sort of damping mechanism that I didn't recognize when I took it apart or that I forgot about. Maybe you can find some information about it.

In either case, I don't think a damper would affect how you set the toe.

In case anybody is interested, I looked up the castor on the TC is 2^o 30' +30'. As Brian and JB mentioned it is not adjustable unless you have the fancy A-arms. I don't know if 2^o is significant. I agree with Ron that some cars have more self centering but I don't think I ever gave it a thought till he mentioned it!  I have a camber gauge so I could measure the caster but since I can't change it I've never bothered.

[ron parola]

Well, if it has a stock rack there is indeed a dampener; look on the drivers side of the rack there is a big nut with a small nut on top of that, the small nut can be removed and a grease fitting installed but the large nut is where the spring loaded "pinion pressure pad" is located. The tension of the spring inside is set by shims ( I went and looked on mine)underneath the head of the large nut; tension should be 2lb (.9kg) load with a lever arm of 8in (23.3cm) on the pinion  or just a bit of spring pressure. Also these are odd little cars; with skinny tyres caster doesn't help a whole lot, wider the better. With a very light frt end you can have a LOT of caster (Fiat 850 sport spider 9 degrees!) because it doesn't make the car hard to steer when stopped. With wide tyres and a lot of caster you notice the car is lifted and the tyre leans outward ( look at german cars) the weight of the car is trying to push the tyres straight. Also these things don't have any Ackermann, infact they have a LOT of antiackermann, this is great for loading the outside frt tyre around corners on a race course but not so good on the street, they are twitchy at speed. Hard to deal with that since this are frt steer cars (rack in frt of suspension. I've machined my steering arms to move them closer to the disc but that is just less antiackermann. Does this help AT ALL? cheers rp

[BDA]

Thanks! I knew about the shim setting but figured that just adjusted the pressure of the rack against the pinion. I didn't realize that it had any dampening function.

I guess 3^o of caster isn't much when compared to 9^o! That certainly adds some context!

[jbcollier]

"Anti-ackerman" is there to increase high stability in corners.  It's a good thing.

[BDA]

Many years ago (mid '70s) I thought I had read that ackerman wasn't worth the effort (I believe because the tire slip angles would take care of it) even though it made sense at the time to have the inner wheel turn at a sharper angle (I don't recall ever hearing about anti ackerman. I notice that F1 cars do have (anti) ackerman so I guess for them, at least, it does make a difference.

How does a simple rack and pinion implement any kind of ackerman since when you turn the wheel, the rack rotates both steering arms through the same arc - or am I missing something?

[ron parola]

It isn't the type of steering box but the angle of the steering arms at the wheel spindles. In theory you want the steering arms connected at the vertical axis the wheel spins around ie, ball joints and in this case trunnions. The arm then comes back (rear mounted box) towards the tie rods but at an angle pointed to the rear centre of the diff, or centre of the car centred on the rear axles. The angles involved cause the inner wheel to turn sharper, that accounts for the difference of the width of the car from wheel to wheel around a certain radius of corner. If you think about it no or anti ackermann then, around a corner, in effect you get toe out. Good for cornering, heats the outer frt tyre and as the inner one is less loaded causes the outer one to grip better. Ackermann makes no difference in a straight line; there are  no angles involved, look towards toe and caster for that also bump steer on these guys. That said it does come into effect in the real world of rough roads and turning. cheers rp

[ron parola]

oops, sorry should have said with anti Ackermann you would have toe IN in a corner rather than out, I really gotta learn to pay more attention rp

[BDA]

Thanks for the explanation, Ron! That helps a lot!