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General
There is little to discuss about the uses of early or late gearboxes
other than the use of caution due to drive shaft lengths and speedo drive issues, but they
are important points. Please read this section to avoid problems, and for more information
about driveshaft refer to the front suspension section.
For anyone contemplating using one of the later
engines with an earlier car, please note that the crank position sensor fitted to the 9
o’clock position of the rear crankcase cover will require that the appropriate
gearbox bellhousing flange has a suitable cut-out , as the later ‘boxes do.
The gear linkage from the new ‘box appeared sloppy, so the linkage rubber bush from
my old box was transferred to it - they appeared identical, even though the design of the
linkage mechanism is fundamentally different.
The gearbox is filled with Mobil fully synthetic gear
oil.
The decision was made to use the mechanical speedo
drive (see saga below), but the Nylon speedo output worm gear was found to be cracked. A
new Alfa replacement was sourced from Alfa II.
the complete speedo drive, dis-assembled
- the clip on the right locates and retains the shaft.
the new gear is in the middle, complete
with a new sealing 'o' ring, the cracked gear on the left
is clearly visible
Apart from this, the gearbox was left mechanically
untouched, with the casing cleaned to make it look tidier.
Gearbox speedo drive and driveshafts
Having determined that the later gearbox from the
donor car appeared to be in satisfactory condition, and appeared to have a considerably
longer 5th gear than that fitted to the old ‘box, I decided to fit it. Unfortunately,
the gearboxes fitted to 33’s are all electronic speedo drive. To convert the speedo
to electronic drive was unthinkable, so the only other option was to swap the drive gear
out of my old ‘box into the new.
Unfortunately (you will be seeing the word ‘unfortunately’ many many times in
this report….) you cannot just pull out the output drive assembly from one ‘box
and install it in the other as the lengths of the shafts are different to take account of
the lack of brake parts.
The speedo drive gear is fitted to the right hand gearbox output shaft, which is a part of
the output drive and housing assembly. It is a simple press fit on the shaft, but as the
housing completely surrounds the gear, you cannot get to it to remove it. It was arranged
that I would remove the output drive housings from the old and the new gearboxes and ship
them to Alfatune in Liverpool, where Gus Lambreu would get one of his guys to swap them
over for me. Take a look at the picture for the electronic speedo drive phonic wheel that
has to be removed.
Unfortunately, as I started to get the bolts out of the new ‘box, one of them seemed
suspiciously loose. When I checked, my worst fears were confirmed - a stripped thread.
Now, for anyone that didn’t know, Alfa have a predilection for using Metric Fine
threads, and these were 10mm x 1.0 threads, tapped straight into the gearbox casting. To
cut a long story short, I ended up using a 7/16th UNF tap, which allowed me to cut the
thread directly into the stripped existing thread, and a suitable bolt was installed.
Problem solved.
Then I turned to the other ‘box, to get the donor drive gear. One of the bolts was
stuck absolutely solid, and unfortunately these buggers were the old allen bolt head
"Unbrako" type, which require an 8mm allen key. I tried with an allen key with a
bit of pipe stuck on the end of it to get more leverage, all I did was twist off the end
of an expensive allen key. I used an allen bolt socket bit and a LARGE breaker bar, and
all that happened was I got arm strain. Luckily the bolt head, to its credit, did not
round off. Next was the impact driver - nothing. Eventually, I got a blowtorch and used a
heat / impact driver / big breaker bar / cool with WD40 cycle, and after about five cycles
it finally gave with a crack.
By this time the bloody thing had used up a day on it’s own, and the whole gearbox
saga had taken two and a half days! I had guesstimated a half day for the lot….
I finally got the car up and running, only to discover that
the gear rations were identical to the 'box I'd taken out.... You live and learn.
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