Borrani: more than 85 years of history and success
On April 22, 1922 the Italian company “Rudge Whitworth Milano” (in Italian; Società Italiana Ruote Smontabili Rudge Whitworth) was established in Milan, with a share capital of one million and 200 thousand lira. The owner was Carlo Borrani.
The Company was located at Via Ugo Bassi 9, and its activity was the production and commercialization of “wheels for cars, motorbikes, cycles and equivalent” as per notary act at the Chamber of Commerce.
This was the official beginning of the remarkable Borrani wire wheels story. Production started with a license of Rudge Whitworth from Coventry, Great Britain, which had registered a patent for mounting a wheel on a hub by a unique splined drum, fixed by one central lock nut.
This enabled an easier and faster mounting and dismounting of the wheel. This also aroused the interest from the most important racing cars constructors. After just 12 months from establishment, Alfa Romeo, Auto Union, Bianchi and Lancia started to equip their racing and deluxe cars with Borrani wheels.
Later in the early 30’s Borrani started to experiment with light, rigid aluminum rims (cerchi DD) to replace the usual steel wheels with impressive results in the field of competition. This was the beginning of a “new way” that still today, makes the Borrani wheels unique and recognizable in the world. At the beginning of 1939, forced by the new Italian laws the company modified its name into Carlo Borrani S.A.
Times of growth
In 1955 the premises in Via Bassi became inadequate for the rising monthly production volumes, that increased from 1.000 to 1.200 and then 1.500 wheels per month in the 6 years thereafter.
The company again changed name and merged into “CMR –Costruzioni Meccaniche Rho S.p.A.”, and moved to Baranzate on North-Est edge of Milan.
The production of wheels went on linked to the Ruote Borrani Milano trademark. Ten percent was devoted to racing cars. Ferrari was the best customer of Borrani at that time. This alliance was not accidental, as in 1924 the young Enzo Ferrari ran and won the Acerbo Cup in Pescara with a car equipped with Rudge Whitworth Milano wire wheels.
The collaboration between Ferrari and Borrani also experienced some disagreements as in 1952 when Ascari had to give up the 500 Miles in Indianapolis because the hub of his Ferrari broke.
“Drake” pounced into Cesare Borrani’s office, Carlo’s son, for a long, hard and sparkling discussion coming to the conclusion of manufacturing special molded hubs.
Borrani also became famous in the motorcycle world as supplier of renowned manufacturers as Benelli, Gilera, Guzzi and MV Agusta. While among car makers even Ford purchased the rims for the first version of its mythic GT40 from Borrani and used them on their Le Mans race cars.
Borrani wheels were standard equipment for Alfa Romeo, Ferrari, and Maserati racers winning 8 F1 Driver World Championships and 2 F1 Manufacturer World Championship (Vanwall and Ferrari) between 1950 and 1961. Borrani wheels contributed also to countless Ferrari and Maserati victories in Sport and Prototype races, from Le Mans to Nürburgring, from Sebring to Monza.
Thousands of national and international victories were achieved on Borrani wire wheels during this period which is why we still use the phrase; Borrani. Wheels of Glory!
The Bimetal era
After a successful period for wire wheels, the cast-aluminum wheel gradually took over the market as first equipment. Looking for new ways, Borrani started to mount a pressed steel wheel disc in their existing aluminum rims. These ‘Bimetal’ wheels, which were produced already in 1950 as CABO wheels, had their fair share of success and were mounted on famous brands as Alfa Romeo, ASA, Abarth, Fiat, Lancia, Maserati and others. In the early 60’s, Borrani wire wheels became an exclusive accessory on new cars but in the end-sixties, cast light-alloy wheels became regular equipment on racing cars, alongside the increase of performances and dimensions of tires. Change in trend and design put wire wheels aside from mass produced cars and Borrani’s volumes went down in the 70’s and 80’s. Only a few years ago, the annual volume was less that 300 classical wheels per year.
Since February 2004, Ruote Milano holds the license for the manufacturing of Borrani wire wheels. It is located in Rozzano, in the southern area of Milan. The new premises have been adapted for future growth and facilitates a production for the classical wheels by highly skilled workers, who guarantee quality and compliance with originality and tradition. They make use of the extensive archive which contains more than 5.000 original drawings. Over the last years, the availability has been improved to more than 500 references and production is making over 1.500 classical wheels.
In the near future, Borrani will use it’s very strong image and association with famous car-makers like Ferrari & Maserati to launch exiting new lines of classical and technologically advanced wheels for modern sports-cars.
MATERIALS & TECHNICAL DETAILS
It is extremely important to highlight the difference between motorcycle and car wire wheels. Building materials are very different. For cars, the use of stainless steel spokes is not advisable at all because the side (lateral) forces applied during steering and braking which could cause the loosening or braking of the outer-laced spokes.
The spokes are manufactured with bona fide steel 39NCD/4 80-90 Kg/mm2, this will result in higher strength and flexibility and will make the spokes able to resist to the side forces without reaching the breaking point.
Our special alloy 6082 used for manufacturing the rims have been developed & perfected over decades to allow the maximum resistance and the minimum weight, the HB hardness level is a very important aspect. The proper alloy will make the cold dimpling possible, but will keep the rim strong enough to be repaired in case of small cracks. It also enables for perfect roundness with a very small tolerance. Hot dimpling can cause heavy deformation of the rim during the cooling process, this is another reason why today we manufacture rim-thru spinning without welding, which used to be the weak spot in the past. Some wheels were manufactured with a heavy-duty rim and without dimples, some of those are still available, even if tests showed no improvement and it only added more weight. For this reason this was abandoned.
As far as the centre-pieces are concerned, we have 2 products, the standard one for regular street use and the one with competition specs made in C/45 steel from a solid hub. The unique material combination between hub, centre-piece, spokes and rim results in the Borrani wheel-quality. The use of other materials (specifications) will compromise the safety of our products. Therefore it is strongly advised to have your Borrani wheels serviced/restored only at the Borrani factory.
Others claiming they can do Borrani restorations are not official and do not use the proper materials & techniques.
Our complete Borrani archives include all the original projects and drawings for standard cars, and for special cars equipped with Borrani wire wheels. This forms a crucial support to answer the wide range of requests from customers all over the world.
All Borrani wheels were developed in close collaboration with the related car makers as a complicated and sophisticated technical product. Borrani wheels in most cases formed an integral part of the car’s homologation and were also extensively tested as such. Borrani wheels are unique products for the following reasons:
- the materials used for hubs, rims, spokes and nipples
- dimensions and tolerances for hubs, rims, spokes and nipples
- technical specifications such as hub threads and rim shapes
All Borrani rims are identified by a stamped RW-code of four or five figures, the unique Ruote Borrani Milano stamping (there are several variations), and a stamped internal production number. The codification also applies to the hubs. All numeric codes correspond with our technical-and production documentation.
Over the past 85 years we designed close to 5000 different wheels. Each wheel is unique because of it’s own mounting pattern, the number of spokes, dimpling or drilling, centre or outer laced, number of rows, off-set and special centre-pieces.
The RW (Rudge-Whitworth) is a progressive number that individuates the original design of each wheel, most of the time realized in collaboration with the car maker according to vehicle weight, use and specifications.
Each Borrani wire wheel has a single application because it’s made specifically for a single type of car. It is not advisable or safe to mount them on another car, not suitable for this reference.
Each product is identified by a marking on the side of the outer edge of the rim, it will show the RW number, size and type of rim (record stands for light-alloy). At the back of the wheel you will find the production date and serial number used for the factory records. In 85 years, the markings and positions have been changed.
But you can still request vintage printing for concourse purposes (on the outside only), but actual production date will apply.
The basic aesthetical finishing are: either grey painted wheels which are specially advised for race-use since the spoke chroming will brittle the material. Second and mostly used/chosen is hi-polished rim with chromed spokes and centre-piece. These are the original finishing's for Borrani wheels, any other superficial treatment will be considered a “special order” and not original.
To balance tires on bolt-on wire-wheels (tipo S), the standard process like cast or steel wheels should be applied.
To be able to balance the wheels with centre-lock system correctly, one must use the correct cones. A 60° cone at the bottom flange and 20° cone at the ring of the centre-piece, the balancing shaft doesn’t need to be splined.
The most popular typologies are 32-42-52-62-90 with the proper cone diameters. Some later models such as RW 4039 have bottom cones of 50°.
Please refer back to the database at the factory. Absolutely do not use standard 45° cones which are mostly used on regular balancing machines especially pay attention to not use the back of the centre-piece flange as a mounting surface, it will result in false reading. Balancing should always be performed by professionals with experience in centre-lock systems.