Jim Clarks over/under drive

[h20hamelan]

yes and no
yes I would like it to work as Dave makes it sound easy
no, i have too many kids, family, house, business etc

I accept Your previous looking and thinking, obviously You have put considerable time and energy into it. So thanks. I am not sure if David has specific examples, contacts , photos, etc, or anything other than his word this has been done.

Long and short.
ied prefer the original box, and I really like hitting a button to add more grip when maybe things are about to go bad quick. And as we know, not depressing the clutch to shift a gear keeps the present grip.

Maybe there is hope with Mark Kinman and the UK government. Anyone think we could plead our case to the Courts? We are I am sure, all well aware of Restorative Justice and the benefits to society over incarceration.

[h20hamelan]

Dave can not recall who or when. just that it fits.

"we have had people mount them solidly to the diff flange to flange and bracketed back so that everything moves together"

[Davidb]

"Dave" may be thinking of this:
http://www.wobmf.co.uk/derby-driveline-choices-0

Scroll down to Option 3 and you can see a Laycock J type overdrive attached to the nose of the diff. Now imagine what this does for unsprung weight!
Ps. I own a 1935 Derby Bentley and that is why I have a Laycock overdrive sitting on the shelf waiting for me to fit it...

h20hamelan: you seem to be totally ignoring the fact that the Laycock overdrive is wider than the Elan chassis-by quite a bit-look at my photo again.

The Ford Type 9 gearbox is probably the best answer.

[h20hamelan]

Yes Davidb. Your photo clearly shows no room.
I suspect if the adaptor or connection was where OverDrive Dave speaks. It would be close to fitting.

It would take someone with a frame and a overdrive unit to be more exact, unless You Davidb have overhead photos, and with the OD snug to nose. What was your plan. To run an intermediate shaft. Or direct connect?
I am not calling you or Uk OverDrive Dave dishonest.
Simply, it seems there is no confirmation either way.

I hope to keep pestering Dave for knowledge.
The Gear Vendor Units are about the same size. So i dont think thats much better. Then again...I would still prefer the proper 4 speed, with an overdrive.
It will be many years most likely for me to play with a 5 speed transmission swap. Where as I have more interest in overdrive.

[Davidb]

"Yes Davidb. Your photo clearly shows no room." Hold that thought!

This is my last comment-Like others on the forum I only have so much time to waste.

The Laycock J type overdrive is wider than the Elan chassis. If you somehow managed to install it-by widening the chassis at that point and with the body removed from the chassis, you would not then be able to refit the body without modifying the body (substantially). Having done this, either by using a connector shaft from the gearbox to the o/d and from the o/d to the diff, or by bolting it to the nose of the diff (which would require major chassis modifications) you would then not be able to service/repair the unit without removing the body of the vehicle-the oil needs changing every 10,000 miles-how are you going to do that?

The Laycock overdrive was designed preWW2 as a means of adding a cruising gear to existing gearboxes. The vehicles using it had separate chassis that allowed room for such a unit. The advent of five speed gearboxes in the fifties and sixties made it redundant for all but a manufacturer such as Volvo who did not have the means to develop a five speed box of their own.

Over and out.

[rcfurse]

I understand that the gearvendors unit is capable of handling considerably more torque than anything a TwinCam is going to throw at it. Should we talk to GearVendors about making a unit that is (say) 1/2 or 3/4 size? It would then fit into the chassis with a two piece propshaft.
Given the number of people on the forum that want a cruising option for the freeway/motorway it would appear that it might be a viable proposition.

[prezoom]

Anyone looked at the "D" sized overdrive as used on the MGB's with the three main engine and non-synchro 1st gear? From pictures I have seen, it appears to be smaller, but has the solenoid external and looks to be close to the Elan transmission mount. This was the pre "J" unit.

[h20hamelan]

it seems to me, finding a shop that will mate the two units to be the best option
most likely cutting the matting ends, with correct joining of Overdrive output, and Differential input.

OverDrive Dave did not specify which unit was fit

[kwhittle]

In period Hewland made a 5 speed version of the Ford 105E gearbox. To suit L7, Anglias etc
It was successful but FIA had a problem with it
Kevin

[alanr]

I sort of get the impression that we are all looking for a relatively cheap solution and whichever way, either T9, T75 gearbox, Isuzu or other 5speed gearbox or Overdrive, one thing is for sure any conversion is not going to be cheap or straightforward!
Personally I would love an Overdrive having been used to one in the past in other cars and would put my hand up for one in an instant if it could be done at sensible money.
Realistically though I think possibly the T9 conversion sounds the way to go.
The shortage of supply of alternative gearboxes, this side of the pond seems to make using othe boxes a bit too difficult. Unless of course our friends in 'The colonies' sees a business opprtunity here to supply us in the UK with a supply of suitable 5speed boxes?

Alan

[Davidb]

In period Hewland made a 5 speed version of the Ford 105E gearbox. To suit L7, Anglias etc
It was successful but FIA had a problem with it
Kevin

I had one-fifth gear was 1:1

[bigvalvehead]

The T5 gearbox has numerous ratios with o/d 5th from .8 to .63
It will fit and a bell housing is available from RWD Motorsport.

Link to ratios here
http://www.britishv8.org/articles/borg- ... d-tags.htm

Gearstick is in correct place if you use a S10 rear housing.
Not much difference in weight as T5 is alloy cased.

Speedo can easily be sorted by using a GPS drive to original speedo.

Also concentric clutch kits available from Burtons

Cheers
Dave Hughes