Eligibility: Potted history of calipers

It has been questioned whether ‘four-pot’ calipers were in existance prior to 1981. With the valuable assistance of Steve Carthy Motorcycles, several professional elite riders of the day and period manufacturers we have managed to gather the information outlined below. Their responses demonstrate a corresponding pattern and it seems that anything more than twin-piston calipers were not seen prior to 1982/83 at the earliest.

Terminology

The word ‘Pot’ describes how many hydraulically actuated pistons there are, this can often be misunderstood due to the external appearance of the caliper. For example, the Yamaha caliper shown in the eligible photographs below is a ‘twin-pot’ or ‘two-pot’, however this is what Jon Ekerold refers to as a ‘one pot’ in his message below. The AP Racing drawing depicts their later ‘four-pot’ caliper which has a pair of pistons in each side (1983).

AP Racing CP3086, their first ‘four-pot’ caliper design drawing

Gathered information: Jon Tait, 920 Engineering (formerly known as AP Lockheed):
AP Lockheed did not ever produce a production 4-piston motorbike caliper for race or road, so all available evidence suggests that AP Racing’s 1983 design is the first of its kind. Richard Bass designed the first 4-pot bike calipers for AP Racing, commencing in November 1983.
AP Racing & AP Lockheed were part of the Automotive Products Group in the 1980s with AP Lockheed being the road brakes division and AP Racing the competition department, additionally taking over the development of motorbike brakes.
AP Racing moved to Coventry in the early 1990s, and was bought by Brembo S.p.A in 2000.
AP Lockheed was subsequently purchased by Caparo, before being acquired by the Liberty House Group and rebranded 920E in 2015.”

AP Racing Coventry:
“The CP3086 were produced from November 1983” First issue drawing supplied, dated 1983.

Brembo’s P4/32 was released for customer purchase in 1983

Ian Edwards, Mode Performance:
“I can confirm that the P4/32 (20.4425.03-04) caliper, as shown in the picture, has been confirmed by Brembo that it was first designed on 15th July 1982”. This information has been clarified by designer Eugenio Gandolfi formerly of Brembo S.p.A. and passed through Ian Edwards at Mode Performance – the UK Importer for Brembo Racing.

Jon Ekerold:
“I used Brembo calipers on my Bimota, and Lockheed brakes on the TZ’s, but I suspect they were one pot calipers. The lump of iron which passed for brakes on the standard TZ’s were definitely one pot calipers. I think my 500 Cagiva was equipped with the first twin pot brakes I ever used, which i recall were Brembos”.
Page 128 in Jon’s book shows his first outing on the Cagiva in 1982 with a four-pot Brembo in the photo. Page 125 shows the World Championship winning machine with a simple twin piston caliper.

Klaas Tjassens, artist and author of The Flying Finn:
“No, I cannot remember having seen any TZ350 with single disc and 4 pot caliper”… “Ferry Brouwer answered my mail with: Yamaha never had a TZ350 with a 4 pot caliper”.

Eligible 350cc front brake caliper examples

The requirement is to be ‘of the period’ – this means the configuration, design and visual appearance. We do not produce an exhaustible list of manufacturers; riders will need to do their own research and enquire with any unusual requests. The example calipers shown below are readily available and widely used to good effect by the fastest riders in post classic Championships. Twin or single discs may be used.