Mine cost a couple of hundred quid using a S/H O/D unit and breakers yard props.
I used it to pull a flat bed goose neck with a 6000lb antique JD pulling tractor and never had any trouble splitting the lower gears. If the O/D won't engage you can continue driving as normal, if it won't disengage reverse will wreck it. I have had a Laycock J type mid mount OD in my 1976 Ford F250 with a 5.9 Cummins diesel,BW T19 trans and 3:73 rear since the early 90’s. My 'design' can be swapped back to standard in an hour. The switch should be attached to the gear lever to remind you to drop the O/D first.
The O/D should be used SOLELY as a 6th gear for cruising, it's pretty sturdy but I won't advise slit gear changes or continued thrashing at max torque. Remember the O/D will increase the speed of the rear prop by about 20% if you go for a top speed as opposed to fuel economy. The props should be modded and balanced professionally. A steady bracket is needed for the rear end of the unit.įacilities to machine/fabricate 2 modified propshafts to connect the MT 75 to the O/D and the O/D to the back axle. The front ally plate was mounted on the rubbers. I used engine mountings for mine attached to a 2" x 2" angle bolted to the van floor. The G/box output shaft is shortened and the prop flange welded on.įacilities to machine/fabricate a support bracket able to stand the torque transmitted from the O/D casing. A second plate in front retains the bearing and holds an oil seal to retain the EP 80 in the O/D.įacilities to machine/fabricate the G/Box output shaft to accept a propshaft flange. This holds the O/D front bearing in place and becomes the front mounting of the now standalone O/D unit. The ally sheet is to fabricate a copy of the gearbox casing face to which the O/D extension attaches. You need the gearbox output shaft modified to accept a prop flange.Ī sheet of 1/2" thick ally. I don't have pics, I can sketch the details from memory.īriefly, to use a Laycock O/D unit as a 6th gear you need:Ī good working (transit size) Laycock O/D, either flange or sliding joint output AND the gearbox it came with. How robust is it? Does it eventually eat itself? How much work is involved? Could it be done for significantly less than £800?Īlso interested in general info on the Laycock o/d unit. I would be very interested to learn more about the possibility of converting a Transit Laycock o/d unit into stand-alone. The problem is, these units are around £800 it would bring the revs down to 2,402rpm at 60mph (I'm currently pulling 3,333rpm at 60mph). With this unit from Overdrive Spares I would get a 22.2% (0.788) reduction, which would be slightly better than a change from 5.83 to 4.63, i.e. I had planned to change my 5.83 rear axle to 4.63 (which would give me 2,421rpm at 60mph), but with the 4x4 I have to be able to match the front and rear axle ratio, and this is proving almost impossible. (There is no room between the gearbox and transfer box). With a County, I need a stand-alone unit which would go immediately behind the transfer box. Have been looking for a stand alone o/d unit myself.