The 275GTB was the first of the Ferrari GTs with fully independent suspension and with a transaxle designed to better distribute the weight front to back, this model has sensational manners and feels very planted through corners.
This particular car came to us because the transaxle had seized and we were tasked with establishing why this had happened and to rectify. We were also asked to give the car a thorough ‘going over’.
This car is steel bodied and is fitted with a straight drive shaft from the back of the engine to the transaxle. This means that surfaces must be perpendicular and straight in order to ensure no twisting along the path of the drive shaft. Later models were fitted with a torque tube to add extra stiffness and guarantee a straight path for the drive shaft. The centre bearing is hard mounted, which transmits vibrations into the chassis and we like to rubber mount this.
In common with other carburettors, the 40 DCN3s in the 275 are manufactured in Mazak, which is a magnesium zinc aluminium alloy and results in very smooth castings, but this material is soft and easily distorts, particularly with the 40 DCN3s, which are small and thin walled in order to fit the small space available in the V12 configuration.
The carburettors were stripped and were found to have distorted with age, so they were machined so that the butterflies achieve an air tight seal. We also found that the butterfly axle was leaking air and this was modified with a chamfer. The butterfly retaining clip restricted airflow and its profile was reduced. The carburettor mating surface was warped, again causing air leaks and was machined flat. All this attention to detail resulted in precise and snappy throttle response and accurate control of mixture across the rev range.
The throttle connecting rod of the 275 has a tendency to twist and we usually modify these so that the carburettors all work precisely in unison delivering the same mixture to all cylinders giving balance to the engine. We also like to move the throttle cable so that it doesn’t have a kink in its route, helping to provide a snappy and precise feel to the throttle pedal.
The 250 and 275 Ferraris were known to have weak braking and we are able to significantly improve the stopping performance with an upgrade kit comprised of a larger servo with 30% more surface area that snuggly fits in the existing location to provide more assistance and more vacuum is provided with a storage tank installed out of sight in an empty void behind the front offside wheel arch. This results in a dramatic improvement in braking.
We replace the original graphite water pump seal with our upgraded lip seal product which has no visible change in appearance but becomes as reliable as any modern water pump.
We are able to install an electronic ignition upgrade if requested which means that once set, the timing doesn’t need adjusting as soon as with mechanical points.
If you have similar needs or problems, please contact us a call and we will gladly offer what help we can.