Suspension Settings

[BDA]

Nero, what alignment specs are you using? The S2 spec for rear toe is 3/16" in. to 0. The TC spec is 1/4" to 1/8" in. Using this site (https://robrobinette.com/ConvertToeInchesToDegrees.htm) and a tire diameter of 23.1" which should be close to the diameter of a 185/70-13 tire, I find that 3/16" toe in is equivalent to .466 degrees. Unless I made a mistake (or the calculations this website makes is seriously flawed), your .5 degrees toe in is actually a little more than specified. Maybe somebody can check me on this.

Do you have a fully adjustable front suspension (i.e. spherical rod ends on the inboard side), you would need to adjust them for more caster. Otherwise, JB is right. Something is bent. Since the stock front A-arm pieces are designed to bend and absorb energy in the even of an accident, finding one that is bent is not that unusual.

[RoddyMac]

Kevin W sent me this info a few years ago, taken from the Lotus 47 Spec and Maintenance notes: 

W base 91”
F track 53"
R track 48.5"
Height 40"
G clearance under front box 4.75"
Under rear hoop 5.25"

All with driver and ½ fuel load

F toe in 1/16"
Rear 1/8"
F Castor 3 deg

F camber 0
Rear ½ deg neg

Wheels 7.5F, and 10 rear

Anti rolls bars F5/8”
Rear 11/16”

Front springs 188lb
Rear 218 lbs

It may be of some help in setting up the replica 47 chassis.  Definitely take John C's advice and check the rear thrust.  Mine was out by quite a bit which caused some interesting handling. 

[Clifton]

It seems strange the caster is so low, on both sides. I was complaining about 2.5  degrees.

[jbcollier]

Ah, now I understand your readiness to adjust the castor.  It’s because it is adjustable on your set up.  47 suspension, especially at the rear, bears little resemblance to a stock Europa.

[EuropaTC]

Nero, what alignment specs are you using? The S2 spec for rear toe is 3/16" in. to 0. The TC spec is 1/4" to 1/8" in. Using this site (https://robrobinette.com/ConvertToeInchesToDegrees.htm) and a tire diameter of 23.1" which should be close to the diameter of a 185/70-13 tire, I find that 3/16" toe in is equivalent to .466 degrees. Unless I made a mistake (or the calculations this website makes is seriously flawed), your .5 degrees toe in is actually a little more than specified. Maybe somebody can check me on this.

I got something similar by a different reference - included as an attachment here. The chart is intended to convert mm to degrees but you can obviously get an idea working it backwards.  The rear doesn't look wildly out of range to me.

What did surprise me was the front toe at 1.3deg/wheel, 2.6 deg total. At first I thought I'd read mm and passed on, but after BDA's post I re-read it and using this chart on 2.6deg it comes out as approx 15mm. Huh ?  Am I reading this wrong or did you mean mm not degrees ?

Without checking my latest notes I can't be certain but I seem to think mine is set around 1/16", (approx 1.5mm) at the front. I have run the car parallel in the past without undue problems on our motorways but have settled back on the factor ranges for a while now.

Brian

[Nero]

We increased the toe just to see what difference it makes. As it did not had a big impact we will reduce the toe again.
We use S2 data for reference. I would consider a fault with the lower arms when one side would be off and the other is fine but both are equal. The front has standard bushings but we can move the arms, so caster is adjustable.

[Nero]

It looks like we found the reason for the none existing caster yesterday. The upper arms assembly on the front of an europa is asymmetrical by 7mm. It took me about 10 minutes to find the jig for the adjustable ones that are on the car. The jig has the same 7mm offset. After taking off a wheel we found the arms to be mounted upside down. So we will take the upper arms out in the weekend and that will hopefully solve the problem.

[EuropaTC]

It looks like we found the reason for the none existing caster yesterday. The upper arms assembly on the front of an europa is asymmetrical by 7mm. It took me about 10 minutes to find the jig for the adjustable ones that are on the car. The jig has the same 7mm offset. After taking off a wheel we found the arms to be mounted upside down. So we will take the upper arms out in the weekend and that will hopefully solve the problem.

   now that's a good answer to find, and in one way a confirmation of Chapman's original theme of not wanting adjustable suspension components on his road cars

Make the suspension adjustable and they will adjust it wrong -- look what they can do to a Weber carburetor in just a few moments of stupidity with a screwdriver.

I don't know if he actually said that, but it wouldn't surprise me. I've got adjustable lower links and know only too well how I can mess it up !

Good to know you've got a potential solution, let's know how it all works out now.

Brian

[Nero]

It´s been a while now but I was able to get the castor to 3 degrees with some adjustment. I knew that castor has a big impact on a car but the difference is actually huge. I also found a good shop for the alignment with a young guy that really knows his stuff. As for now the toe is 1/16“ toe in at the front and the rear(both wheels, not to each wheel). First I was not sure about the straight line stability with such low toe, but it’s actually very good. There will be some more testing with the toe but for now it’s going to stay like that.
Thank you for all you help I really appreciate it.

Denis

[EuropaTC]

Hi Denis,
Good to know you've made progress and are happy with the results.  It's always worth a final post to let everyone else know what you've learnt because it all adds to the general pool of knowledge.
Cheers
Brian

[BDA]

Nero, is your caster actually adjustable or did you adjust it with washers? I suspect that increasing front caster would compensate for minimal front toe in since it also enhances stability (though I think I've heard of others using 1/16" toe in so that doesn't surprise me that much). Your rear toe seems really little for good stability so that is interesting. What is your rear camber?

[Nero]

Nero, is your caster actually adjustable or did you adjust it with washers? I suspect that increasing front caster would compensate for minimal front toe in since it also enhances stability (though I think I've heard of others using 1/16" toe in so that doesn't surprise me that much). Your rear toe seems really little for good stability so that is interesting. What is your rear camber?

The adjustment is done with washers, but the chassis is made with that in mind and you need to put washers in with the assembly, it’s just a question if you shift the control arm towards the front or the back. The upper control arm is fixed(same as a 47) just with chamber adjustment. The camber in the rear is for now .75 degrees.

[Nero]

I have another question for you guys. Can somebody please measure how much droop the front wheel has from ride height? I measured mine and it’s just 3cm(1.2inches). On some occasions the feels like it’s just falling into holes or if you drive over a lower curb stone it just falls down. I have played with the dampers which had no change what so ever. The damper is an AVO unit and also lowered. I have attached a picture. The car goes lower about one cm as soon as you get in.

[BDA]

I'm not sure you can tell much from how much the front suspension droops when you jack it up. Usually, the front springs are preloaded so the rate of the springs and the amount of preload would greatly impact the amount of droop. The same goes for how much the car lowers when you get in. That ie more correlated to your spring rates and your weight. IIRC you have the stock front suspension except for adjustable (for camber) upper arms and using the stock rubber bushes. A reminder: using stock rubber bushes means you need to tighten the fulcrum nuts at ride height.

I've never measured the droop on my front suspension, but 1.2" does not seem out of line to me.

[jbcollier]

Sounds like you are running springs that are too stiff.  I have a lot more sag than that.