Front Suspension Geometry

With the rear geometry finished, I started to the front.

I opted for the adjustable front wishbones which are connected to the chassis with front and rear rod ends.

I used a length of wood (planed straight) and two plumb bobs to project some lines down to the floor.  I drew a parallel line to the centre line so that I could ensure that the hubs were pointing directly ahead.  I then drew on two lines 20 degrees from the centre point to setup the caster.

I straightened the hubs and then measured the camber.  I made sure both rod ends were screwed out the same distance before starting.  I then screwed them in / out to suit.  I found out the following:

1 turn of the rod end alters the camber by 0.3 degrees.

I then used the following method to measure the caster using my digital camber gauge.

On the left hand side:

Rotate the hub to the left by 20 degrees using marks on the floor and the plumb bob.  Rotate the digital gauge to vertical.  The camber angle measurement is then noted (eg. +1.1)

Rotate the hub to the right by 20 degrees using marks on the floor.  Rotate the digital gauge to vertical and take the camber reading (eg. -1.86)

Since one of the readings is negative camber, and the other is positive then these numbers should be added together (ignoring the + & - signs - eg. 2.96

Since I used 20 degrees as the angle of rotation, this number needs to be multiplied by 1.5 to give the caster angle. (eg. 4.44)

Repeat the above for the right hand side.

I did have an instruction manual describing this in detail - I will attach it when I can find it again!

To adjust the caster, depending on which way it had to go, each rod end has to be screwed opposite to one another to maintain the camber angle.

This was a little more trial and error and I didn't seem to have an exact figure for 1 turn of movement.  Although roughly it seemed to be 1/2 turn on the rod end altered the caster by 0.3 degrees.

Once I connect up the steering arms then I can set the front toe.

The settings I aimed for at the front are:

Front toe: 5min toe in to 5 toe out to suit conditions and driving style.
Front camber: 0.75 to 1.5deg to suit track – check for even tyre temp.
Front caster: 4 to 4.5 deg neg to suit driver.

I need to think about how to set the bump steer.......

Rear Suspension Geometry

Apologies for not updating the blog as I go.  I have been steadily working away.

I was trying to get the geometry setup for the suspension as close to what it should be.  Once the car is on it's wheels and bedded in, I will take it to a garage and put in on laser alignment system.  I put in place some steel bars to simulate mid travel of the suspension.

I started off using my brother in-law's Bosch GLL-280 laser level.  I marked centre lines on the chassis, and drew a line on the floor using the laser as a guide.  I then drew two more lines perpendicular (front & rear) exactly 4m apart.  This would then allow me to use trigonometry to calculate the toe angle.  I then strapped the level onto the rear hub which I believed would be the best option to show the toe and camber.

After playing around a bit with moving the rose joints in and out, and the turnbuckle, I have worked out the following:

1 turn of the Upper Rod End (Rose Joint) alters the camber by 0.25 degrees.  It has no effect on the toe.

1 turn of the Lower Rod End alters the camber by 0.16 degrees.  Note: The turnbuckle needs to be rotated by 1/2 turn to maintain the toe angle.

I used the following specification for the rear setup:

Rear toe: 10min

Rear camber: 0.5 to 1.0 deg (to suit track)

I screwed the upper rod end fully in, and then out 2 complete turns which will allow for an alteration of 1 degree without having to alter the toe angle.  To alter the lower joint, the shock absorber has to be unbolted and is a little fiddly with washers etc.  I have seen a GD rear wishbone that had a separate shock mount, so I could maybe upgrade in the future if I regulary track the car and require frequent adjustment.  

I altered the lower rod end and turnbuckle to suit the specifications.  I used a digital camber gauge to measure the camber.  I also checked using the laser and trigonometry.

Once I was happy and within a nearness, I moved all the equipment to the other side.

I then transferred some of the measurements of wishbone length and turnbuckle length to mirror the setup.  When I switched on the laser I discovered that the setup was miles off!  I couldn't understand it.  I double checked measurements and almost came to the conclusion that the chassis was wrong.

I then carefully looked at the laser level.  Although the side is nice and flat and appears to be parallel to the laser, it is not.  The laser sits at a slight angle and over a 4 metre length was off quite a bit!  Also, the laser had to be mounted the opposite way around on the other side, so it was even further off.

Back to the drawing board.  I then used some string and a spirit level and re-adjusted the setup.  This took a bit of time since I had to do the adjustment, then plumb the level against the string at the rear of the car and measure from the centre line.  I then had to move to the front of the car to do the same.  I input the figures into an excel spreadsheet which automatically did the trigonometry calculation for me.

I finished both sides and then moved to the front.......

Handbrake

I have been doing a few jobs lately, with quite a lot of thinking regarding fuel pipe runs and what fuel supply system I am going to use.

I thought that I would get a few things done while I am trying to decide.

I have drilled a few holes for mounting the stainless p clips and have tapped a M5 thread for the bolt.

I will post up some photos when I am assembling the p clips since showing a hole isn't too telling!

I have been trying to work out how the handbrake mechanism is designed to function, and I have decided to modify the lever that was provided with the kit so that it fits above the chassis mount.  Dale's car has the lever above the mount, but the one supplied with my kit couldn't fit.  I have since ground the lever down to fit on the existing mount to match what I think is correct.

Engine / gearbox is in!

For trying to decide how my fuel pipes would run, I thought it would be a good idea to fit the engine and gearbox to see what space there is for the pipes.

My initial idea is that I would put the assembly in and then mark up where I need to drill for the mounts, then take the assembly out again.

My dad came over for a visit and he helped me get the engine assembly in.  Not too much work using the engine crane.

Once the assembly was in, it looked like I could access the mounting holes without much problem, so I think I will leave the engine in!

The only draw back was that because I thought I was going to remove the assembly again, I didn't put in the propshaft.  This cannot go in if the diff and engine/gearbox are in!  I then thought it was much easier to lower the diff, install the propshaft, and raise the diff again.  That is what I did.

I need to finally bolt up the engine mounts, propshaft and diff.