Front suspension dilemma.

[Expat]

I have been the proud owner of a 2012 Superlight R300 for about six months.

 

The front suspension is, of course, wide track. However I have just noticed that the lower LH wishbone is mounted (probably the original got bent) like a narrow track one. i.e. the washers are positioned as shown on page 65; fig 32 of the current (versiion 02/2015) assembly guide. Thje bolts holding the wishbone on look new too.

 

My dilemma is should I:

 

a) Leave well alone and do nothing ?

 

b) Try to put the washers where CC say they should go and re-do the tracking etc.?

 

The uprights seem to have been put together correctly although it's difficult to be sure until I can get underneath it.

 

Very grateful for any advice.

 

[Jonathan Kay]

Can you add a photo? And please can someone add one for an orthodox wide track set-up.

Jonathan

PS: Now you've noticed it the answer's probably going to be to normalise it and take the opportunity to get it aligned: (b).

PPS: I'd also think about talking to the vendor when I'd decided what to do.

[CharlesElliott]

If the only difference is the washers, then it is the castor that is affected.

If you change the washers (and therefore castor), you would really need to re-check both the camber and the toe.

[John Vine]

You say the LH wishbone is set 2-2-2 at the moment.  What is the RH setting?  Whatever you end up with, both sides should normally be the same.

The various washer combinations allow the castor to be adjusted to suit individual preference.  Castor increases with the number of washers between the front mount and the chassis.  So, 0-4-0 is lowest and 4-0-4 the highest.  The more castor you have, the more the steering will self-centre but the heavier it will feel.  It's all pretty subjective, I think.  Racers tend to go for the most castor possible (4-0-4) whereas for road use 2-2-2 is probably the most you'll need.  There are several threads on this.  Try a search on "castor AND washers".

The various versions of the AG give the following:

1. The undated hardcopy version I used on my R400D in 2008: 0-4-0 for wide-track and 2-2-2 (by implication) for narrow-track
2. July 2010: as #1
3. May 2012:  2-2-2 for all cars, making no reference to wide-track
4. August 2014: as #1
5. Feb 2015 (latest?): as #1

 So, I would start with 0-4-0 both sides.  If you feel you'd like a bit more self-centring (and stability), try 2-2-2.  If that's too much, try 1-3-1.  I started with 0-4-0 and ended up with 2-2-2, which I find a pretty good compromise.

JV

[mic]

I would get the geometry checked before changing anything. If the car has been damaged it may have been put back together like that to even the castor up with the other side. 

[CharlesElliott]

Yes, like my car was!

[Expat]

Wow! I'm overwelmed by the quality and quantity of the response and the first thing I'll do tomorrow is call the vendor (Caterham Competition France). Second thing will be to get the geometry checked.

One small point (probably caused by my stupidity), the Caterham drawing as shown below gives the setup for standard, narrow, track. This I have on the Left Hand side and would call 2-2-2

On the Right I have (reading number of washers Left to Right) 0-4-0 Is this correct? or have I totally misunderstood?

[CharlesElliott]

Yes, the picture is 2-2-2.

0-4-0 pushes the lower wishbone forwards. On your picture, 0 washers on the far right (next to nut 7), 4 washers next to rear chassis mount (item 6), 0 washers next to mount 4, and then some additional washers on the very front under the spring washer to make it fit.

If you do 0-4-0, you really want a 1/2" x 2 3/4" bolt (rather than 2 1/2" as standard) on the front mount to ensure enough threads in the boss are engaged.

[John Vine]

0-4-0 pushes the lower wishbone forwards

Shouldn't that read backwards? 

In other words, 0-4-0 gives the least castor, and you would consider using the longer front bolt for 4-0-4. (max castor).

JV

[CharlesElliott]

Sorry, John, you are right. More castor gives increased camber when turning the wheels.

[Expat]

Slowly beginning to understand castor and camber. Hopefully have found a garage to measure the existing setup and will take it from there depending on the results. Measurement of the chassis shows no evident twist or other deformation so the LH side maybe just habit on the part of whoever put it together.

Did a search on "castor AND washers" and am now slightly less confused. One post suggested that a million different answers would be given to a request for the best possible setup , so I wont ask.

However, another did say that different washer positions left and right could be found to make up for tolerances in the chassis build. We shall see.
 

[CharlesElliott]

Can't really go wrong with 2-2-2.