There are 10 images on this page.
The transmission on the
car will consist of the Fiat 5 speed gearbox ( because it fits the engine,
is strong and we have them in stock.), and a Ford Sierra 7" or 7 1/2"
differential unit. Sierra drive shafts will also be used. There are two sizes
of Ford differential and the sizes indicate the size of the crown wheel. My
first choice of diff. will be the 7" unit because it is lighter but it
it proves weak I can fit the 7 1/2" unit. The mounting points for each
housing vary slightly but I will make the chassis accept both sizes. The propshaft
will be a custom made item with lightened parts.
The steering will be rack and pinion using a rack built to my specification.
Column will be CDS rotating in needle roller bearings with a quick release
steering wheel. I will try to make the whole steering system as solid as possible
to give the greatest amount of feed back
As I intend to use the car for tarmac rallying the brakes will have to be
big to cope with the demands. At the front I will use the largest vented discs
I can fit with 4 pot alloy calipers. ( Alloy calipers to keep the unsprung
weight down.) The rear will have Ford discs and calipers as intended for the
upright. Master cylinder choice will be determined by considering the relative
sizes of the front and rear brakes, coefficient of friction of the tyres and
weight transfer when braking. A balance bar will fine tune the choice and
a proportioning valve will cover the varying tyre grip on different road surfaces.
( Wet and dry etc)
The gearbox was stripped
and rebuilt. The Price of components from Fiat was very high. It would cost
£750 to replace syncro`s , selectors and bearings. In this picture I
have lock wired the bolts which hold the selectors to the rods. This is for
peach of mind.
-----------------------------------------------------------
I had never rebuilt a
gearbox before but I took my time and drew diagrams as I dismantled it. The
task was quite easy. I actually built one good gearbox from 3 poor ones and
fortunately one of them had syncro rings that were in very good condition.
-----------------------------------------------------------
A hydraulic clutch release
was required for a few reasons. Hydraulic clutches are easier to route and
they give a smoother action. The Fiat normally uses a cable and rather than
fit a slave cylinder on the release arm I used a concentric combined slave
cylinder and release bearing. This fits into the back of the bellhousing.
------------------------------------------------------------
The actual unit used
is Saab. This required the bellhousing to be machined and an adapter plate
making. Many of the race clutch suppliers sell their own based on the Saab
system but they are more expensive. Another advantage of using this system
is the thrust bearing is the correct size for the Ford clutch plate, the Fiat
one is too small.
----------------------------------------------------------
The gearbox, propshaft
and the differential. The propshaft is steel but all the ends are lightened.
The length gives an indication as to the amount the engine is set back. The
propshaft was in balance to the repeatable accuracy of the propshaft balancing
machine. In other words the prop was showing a slight out of balance, but
if it was taken off the machine and attached again the out of balance would
be in a different position.
----------------------------------------------------------
The Fiat prop. normally
has a rubber guibo on the gearbox, this is unsuitable for my short single
piece shaft so I had to machine an adapter to convert the Fiat 3 bolt fitting
to the 4 bolt fitting on a standard 1300 series flange. There are also 2 kinds
of output on the Fiat gearbox, I used the one which would be lightest. This
is where the reverse sleeve yoke slides out of the gearbox.
-----------------------------------------------------------
The adapter is doweled
onto the 3 prong spider and dowels are provided for drive to the propshaft.
Concentricity of the register on the alloy adapter is important so the propshaft
runs true.
----------------------------------------------------------
When using racing discs
you have to design and make your own mounting bell. The advantage of this
is you can place the disc where ever you want. I machined the mounting bells
from 2014A in the T6 condition. They will also be hard anodised.
----------------------------------------------------------
When machining the mounting
bell it is important to have a large a radius as possible at each change in
section. The holes to bolt the disc to the bell were drilled and reamed with
the disc in position, using the disc as a drilling jig. The holes were then
peened.
-----------------------------------------------------------
The AP Racing 4 pot road
caliper. It has dirt seals around the pistons. The price of these calipers
is quite reasonable. The calipers are radial mount, this gives more freedom
in the mounting brackets.
-----------------------------------------------------------
