Laycock overdrive

[j6393]

I have a 1967 cab chassis with V4 engine and 4 speed gearbox and have been offered a model J Laycock overdrive.
I know it makes a lot of sense to fit an overdrive rather than change the diff ratio by say 25% and I would value the comments from anyone who has already done it.
Standard gearing is pretty close to ideal for local work but is a bit slow for out of town.

[madmark]

hi ,i run a v4 with overdrive ,it works fine out of town well worth the efort in fitting it!

[Soren]

Hi, I drive a V4 Essex with a 4 speed box but i will like to have OD
What does i need for doing OD ?
Can i youse my own 4 speed box or?
Soren

[richiemcs]

Hello, I think I may be able to shed some light on this subject.
I once owned a transit fitted with a J type laycock overdrive and if my memory serves me correctly, the output shaft is different on the overdrive gearbox.
I seem to remember that the overdrive box had a cam which ran the pump supplying oil pressure to the two pistons that operate the cone clutch.
There are also a couple of switches which stops overdrive from being engaged when in reverse.
Hope this helps......Rich.

[madmark]

guys to do this conversion ,you will need a overdrive gearbox ,crossmember that holds up the gearbox and also propshaft mods or propshaft and centre bearing !
the overdrive gearbox from a v6 transit will fit ,but you canot fit the v4 bellhouseing to a overdrive gearbox as this will put the mainshaft to long! so it must use a v6 transit bellhoseing!

also plese note if you have a 1.7 german v4 none of this will fit ,this is only for the essex v4 engine

[Soren]

Thanks, mine is for Essex
Can you tell me how "new" these OD boxes are?
What models Transit shall i look for?
Soren

[madmark]

yes the overdrive was fitted in the mk2 ,and the start of the mk3 transit diesel,for you getting the essex v6 bellhouseing is the problem ,the gearboxes are all the same !
when you find a gearbox you will have to modify the gearbox hold undernieth your van as you will probly have the big bolt that holds your orginal gearbox up! the overdrive uses the crossmember to hold the gearbox ,oh and the front exhaust pipes will need to be modified

[redeemer]

What about a picture or something?

So what does this do exactly, is it like when you have a truck with the High and Low gears, which of them are selected by air pressure or electricaly?
Or you would have a lower ratio gearing , which is like the 5th?

Excuse me of the questions, but here I have only seen standard boxes with the preky 4108 and york in mk1, and late mt75 in mk1/2's with di's.
petrols are rare here.

[madmark]

the overdrive is a unit on the end of the gearbox ,symilar to a auto box ,it runs in the same gear oil as the gearbox , and basicaly when a switch is employed it has a solinoid that makes the unit go bellow the one to one top gear on the 4 speed box! but it will also work in 3rd gear here is a photo of the gearbox in the mk1! you can see in the photo the difrent crossmember and prop and overdrive unti!

[redeemer]

Thanks for the info mate.
Now im clear about what is the overdrive

And , you have a very clean chasis there

[madmark]

mate the chassis will outlast me i think!........its mint!

[manandvan]

re the input shaft:: v6, pinto, and all diesels have the longer one and all the v4,s have the shorter one, i have changed them over but there are numerous teeth counts and diameters over the years, also i have changed the mainshafts for the overdrive one in the past, you could put your own v4 box gearset onto the overdrive mainshaft if you wanted, probably the best option if you accquire a diesel box.

[manandvan]

also re the inhibitor switches: i use a switching relay off the reverse lights to divert the power away from the overdrive when in reverse. the usual inhibitor switches are crap for bad contacts and thats if you can still get them, also use a relay for the switch on top of the stick to save burning it out with the current draw required by the overdrive.

[jpv]

So,

It's easier to find a OD box with the long input shaft or the short one?

Is the bellhousing bolt pattern the same for all Essex and York and di engines? what about input shaft lengths?

It is always necessary to change the gearbox support and shorten the prop shaft.

Is this right?

Does the OD gearbox support member bolts line up with the Transit ones?

Best regards
João Vale

[madmark]

the overdrive type box are all the same the bellhouseing bolt patern are all the same! so if you hve a v4 you need to use the v6 bellhouseing or v4 bellhouseing with a addaptor made to make the mainshaft in the correct place!
otherwise the shaft will be about a 1" to long into the crankshaft!
hope this helps