Vintage vibrato units frequently made the guitar go out of tune when used. And that was even when they could only make the pitch go down. So, imagine the problems if one would be able to pull the arm down and up. There are 2 critical areas needing attention to make sure the guitar comes back to pitch: the nut and the vibrato unit itself. As far as the nut is concerned, some graphite in the string slots at the nut works great as a lubricant. Or one can go all out with a self-lubricating unit, e.g. the Graph-Tech Black Tusq XL nut impregnated with PTFE (also know as teflon) as found on my 3rd style SC-3, Legacy Special and GbL LE-2. Another option is to clamp the strings just behind the nut. Solving the second problem takes more ingenuity. Whereas vintage units just used a hinge or axle to pivot on, modern units use knife-edges or more elaborate engineering to reduce friction. Leo’s rather straightforward solution was to reduce the number of contact points for the bridge plate to pivot on to a mere 2. All this while still ensuring solid acoustic contact between vibrating strings and body. The first submission to the US Patent office for the Dual-Fulcrum Vibrato bridge (DFV) is US Pat. Des. 268,845, filed on July 1, 1980. It shows the complete assembly where the bridge plate has a straight front edge and a single socket for the vibrato arm. Two pivot bolts with a waist in the barrel are screwed into brass insert. These waists are the only parts making contact with the knife edge of the bridge plate hence allowing both decrease and increase of pitch. The whole assembly is shown in US Pat. 4,671,157, filed November 25, 1985, with special attention to the socket and set screw to tighten the arm. For a DFV or Leo Fender Vibrato on an ASAT Classic, the stamped-steel bridge plate was modified (see pictures below) to make room for the pivot bolts. The early pre-BBE vibrato block is made out of zinc, irrespective whether the bridge was chromed (see this F-100 Series II w/DFV) or gold plated (see my 1st X-body Interceptor II), with unfinished die-cast zinc alloy saddles. Starting in 2001, both block and saddles are made of chrome plated billet machined brass. However, introduced on the 30th Anniversary F-100, S-500, and Legacy in 2010, and for the next 6 years, G&L offered an upgrade over the DFV in the form of the DFS Vibrato System, with ‘S’ standing for Steel, using a 1018 cold-rolled steel block and stainless steel saddles both machined from billet material. The only instrument in my collection with such a configuration is the aforementioned GbL LE-2. As of early-2016, the DFS is no longer offered as a G&L Guitar Option.

The springs on the pre-BBE units are an interesting story in and by themselves. Until the end of 1980, only 2 (nickel- or chrome-plated) steel springs were used as seen on the 1980 F-100 Series II w/DFV featured below. These springs use .060” diameter wire and have 37 turns. This worked fine for the default set of 9-42 strings used by the factory but not so much for heavier gauges. So a third, identical spring was added in the center. Now complaints came from the field that the unit was too stiff. As a compromise, Leo used a spring with thinner steel wire, .053” diameter resulting in 43 turns over about the same length, and hence lower spring constant to allow for optimal stiffness over a range of string gauges. Initially, both types of springs looked the same which led to inconsistencies in the combination of springs used. It is hard to count turns on the fly! Hence the omission of additional plating to get the look of the copper-plated steel spring now so famous and responsible for the unique feel of a pre-BBE DFV unit. The current day DFV units use a triplet of standard Fender Stratocaster springs as illustrated below for the GbL LE-2.

An aftermarket DVF has been available since it appeared on the January 1, 1982 price list under part number BV 100 for the bridge and BV 160 for just the arm. These parts were no longer listed in the January 1, 1992 price list. Still available in the G&L Online Store, you can find the bridge (part#051070-100), saddles (part#080520-100), and both the ¼” diameter arm fitting the 1987-2005 DFV (even a gold one) as well as the narrower (.23”) modern arm. For the pre-1987 arm for a socket with ³⁄₁₆” bore, go to Electric String Instrument (ESI) to get an accurate replica.