CP's Trackday 1.6 on TB's re-build

Yes I did think about a 1.8 small block bottom end but from what I gather its a lot of extra work and expense over the 1.6 conversion which is fairly well documented, straight forward and well tested.

Plus would of needed a custom throttle body inlet to suit the 1800 head etc etc.

I have started to look at my suspension/steering geometry with a view to get a suitable set-up once and for all sorted out.
I have trawled the net for info and came across this: ( its for model cars but the principles still apply)

http://www.rctek.com/handling/ackerm...principle.html

I decided to see what kind of ackerman angle has been incorporated into the standard nova reasoning that they naturally handled well so I fitted standard tca's, tiebars etc back onto my car and with the aid of some plumblines took some measurements.
Its difficult to be accurate but what I found was that the cross over point of the 2 lines through the centre of the bottom pivot point of the hub and the steering arm pivot point is well over 1 meter ahead of the rear axle (slightly over 1.3 m according to my rough measurements).

To put it into some kind of perspective that is about halfway between the front axle line and the rear which equals a LOAD of positive ackerman which in turn means that during sharp turns the inside wheel has a lot of toe out induced.

So what does this mean in normal track driving? Well I'm not too sure but I would guess that its effect is un-noticeable until you get to the slowest and sharpest bends and even then it is probably not a negative issue.

However I am going to take some steps to reduce the amount of positive ackerman because I have lowered the car inducing negative camber
which in turn pushes the steering arm pivot into the car away from the hub pivot. This substantially moves the cross where the 2 lines meet further forward which maybe too much. I'm intending to put a lot more negative camber onto the front wheels anyway compounding the effect.

Having had a bit of a think there are 2 ways to reduce having too much positive ackerman:
1. Increase positive caster
2. Move the steering arm pivot point nearer to the hub pivot point

My plan is to make up a totally new solid wishbone arrangement to replace the current tca and tie bar arrangement. This will allow me to induce a lot more positive caster. The other thing I'm going to do is alter the turret top so that I can get top of the spring and shocker about 25 - 30 mm further in and back towards the centre of the car.
I shall keep front wheel track at or very near standard.
I want to stop having the steering knuckle joint seated on the top of the hub steering arm so I'm considering making a totally different hole further towards the hub tapering up so the knuckle can go in from below. This will make the steering arms level & reduce the bumpsteer tendencies caused by steering arms being angled up when lowering the car.

Personally I wouldn't taper the new hole, instead keep it straight and use something similar to these studded rose joints:

http://i10.ebayimg.com/06/i/000/ab/09/b679_1.JPG

Or rose joints and bolts.

That way you can use washers to make fine adjustments. Might seem unecessary, but if you're going to the trouble of re-doing everything, then why not lol

Not a bad idea - cheers:)

Whilst the engine side is awaiting bits I decided to turn my attention to the suspension idea I've had with which I hope to be able to alter the caster.
First I got a standard Nova TCA and tie bar and spent some time measuring stuff up

I had thought that the pivot points lined up but this is not so
http://i205.photobucket.com/albums/b...ionpics003.jpg

So next I traced around the components to get some points of reference and then took some measurements off the car
http://i205.photobucket.com/albums/b...ionpics004.jpg

This gave me a template to refernce off of. Next I started to bend up some 40x40x3mm SHS box
http://i205.photobucket.com/albums/b...ionpics005.jpg

With this set-up I can lay out various shapes to work out whats what. I'm hoping to be able to move the whole wheel forward at least 25-30mm.
Tomorrow, I'm going to cut the various bits to length and tack weld them up

Farking hell Charles, talk about getting the bug back :) Very VERY good to see!! Watching this thread with renewed interest now!

oooo clever stuff

Todays work:
First took my current suspension apart and offered up the key bit to see how it looked
http://i205.photobucket.com/albums/b...ionpics006.jpg

I marked cut lines and cut out the existing rose joint threaded end plate


http://i205.photobucket.com/albums/b...npics013-1.jpg

Nice work.
Some very cool fabrication going on :)