• Peter S30
    16 July 2012 at 14:33 #49430

    The revs with the DB 3ltr Lagonda on motorways are uncomfortable. Who has experience with overdrives especially on this car? Four Ashes are offering one “this mounts in place of the extension housing on the front of the diff unit” I have not asked for the price yet. Who knows alternatives (other than avoiding the motorways..)

    ken douch
    16 July 2012 at 17:28 #49434

    Hi Peter
    As the diff extension provides one of the mounts for the final drive it would seem that interposing an overdrive unit requires some significant chassis mods.
    Why not fit a Tremac T5 gearbox with a 0.8 fith gear.It has been done and requires only a modified rear mount and some trim work.

    16 July 2012 at 18:13 #49435

    Peter ,

    I have heard from several people how good the over-drive option is from Four Oaks, and also comparatively low cost, full details are given here:

    “Overdrive Conversion – Lagonda 2.6 & 3ltr

    An overdrive conversion for the Lagonda 2.6ltr & 3ltrs, this mounts in place of the extension housing on the front of the diff unit.

    The extension is removed & a frame is fitted with the lightweight overdrive mounted to the frame, the floor pan under the rear seat needs modification to allow enough space for the nose of the overdrive unit.

    This kit has been thoroughly tested in several cars, we have fitted 2 of these in our workshop.

    Kit consists of all parts required to fit the conversion inc overdrive & frame, propshaft, speedo cable, inhibit switches & flick switch which is easily fitted in place of the oil level push button (on the ignition switch pad), the overdrive can easily be made to work on 3rd & 4th gears.

    Makes Lagonda’s easier & more pleasant to drive, with the gearing somewhere around 24mph per 1000 rpm if using the STD ratio of 4.1:1 in your diff & crossply tyres, slightly less with radial tyres, the overdrive can be engaged at about 50 mph or above.

    The overdrive unit is based upon a type which was available in 1960s, this is a little smaller than the A type fitted to the DB MkIII, DB4 & early DB5.

    Can be fitted in our workshop or sent out as a kit with full instructions. “

    There is a massive cost difference between this and a Tremec (ca. 10k plus shipping), and this way the originality of the car is not compromised. No trim or visible modifications to the car either.

    I noted the 3.0 litre saloon which had a Tremec box, required a lot more work. For those interested, take a look at this link with the excellent work of Robin Allum:


    Robin never really experienced his DB gear box or its potential, since his engine developed severe problems after only a few runs. He dropped in a Ford V6 and 5-speed box as a temporary solution.

    His DB 3.0 litre engine is now rebuilt and equipped with a Tremec T5, an engine adaptor plate, a hydraulic slave unit that fits on the nose of the gearbox and a special clutch plate to suit. He also fitted a hydraulic master cylinder in place of the mechanical mechanism.

    He received a retirement lump-sum, which he used to good effect. This is very expensive option for a 3.0 litre Lagonda saloon, it costs as much as a good car costs to buy. For a 3.0 litre dhc it would be a different situation of course.

    Personally, I will explore the overdrive option for my 3.0 litre dhc when the time comes.

    17 July 2012 at 17:44 #49442

    I have to agree with Simon. I will be following his lead soon.

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