Great day
Wondering if anyone has some info, regarding Mr Jim Clarks over/under drive unit in his elan
Said to cruise at 80
pm me if you have a few for sale, even one please
Can you clarify what it is you are looking for - is it an overdrive 'box, a 5/6 speed or…just what???
For what it is worth I regularly cruised at 80 mph in my various Elans.
I am looking for any information on over drive units.
its said Jim had one. I also would like at least one.
With a 3.54:1 diff I can cruise at 80mph in my Elan - if I wish.
There is no overdrive available that will fit an Elan so far as I know and I tried a Laycock unit as fitted to most British sports cars of the time:
I am in the market for a similar solution but the constraints of the Elan chassis means that fitting an Overdrive is likely v difficult if not impossible. There are a number of threads here about 5 or 6 speed boxes.
I know that someone has fitted a 6 speed Mazda Miata/MX5 unit to a Sprint. I have seen it but I don’t know how it drives or how it is fitted. I intend to find out because it is clear that there is considerable demand for a higher gear ratio solution. I do have 5.54 and 3.55 diffs fitted to two of my cars and these do allow motorway cruising but a set of Bose noise cnacelling headphones are recommended.
Too right. My iPhone noise meter was peaking at 92dB inside my Elan at 40mph on a local road recently. On a long trip we’ve taken to wearing earplugs.
it has been said by a number of manufacturers that given the number (about 100) would need to be produced to make it viable.
yes, it can be fit to a nose cone.
the typical style today is to be hung off the rear of a box
so we would also need to make provisions for supporting off the chassis to allow the extra weight on the nose of the diff
quafie (no affiliation) included, said it is possible! but they aint gonna do the r-n-d
I am sure we would need to rally support in all communities to make 100 units, even if we could get 60-70 people interested pronto
If it was possible to make an overdrive that fitted inside the chassis between the gearbox and diff it could be fixed there and two shafts would be required. I will investigate. I feel sure that we could get 100 buyers at a sensible price.
Thanks, and Davidb. Do you recall which unit number is on that over/under unit. As there are three sized Laycocks available.
It is much larger looking than my Volvo one which is about 6 inch diameter and 12 inch length. Still most likely not able to fit without a new differential nose.
The smallest Gear Vender would be adequate. Quafie production would be nice.
Would need to look at fitting it in there too. Though on an angle, then sliding back into place should be doable.
That was a Laycock ‘J’ Type. Standard size.
h20hamelan: This unit came from a Volvo-I used to be a service manager for Volvo-this is how big/small they are! I am not aware of a smaller Laycock unit.
Would it not be ‘better’ to find a 5/6 speed 'box you could fit in that small space?
I can’t see any machine shop etc being able to fabricate what you would like in enough quantity to make business sense.
Or am I missing something here (I had no idea that Jim Clark had an overdrive unit in his car).
Does anyone know if there is a difference in size between the OD’s used on the MGB early non-synchro and full synchro gear boxes?
Got to say, the thought of a Laycock overdrive unit on an Elan is pretty awesome. I had a 1500 Spitfire with overdrive and it was brilliant fun. Such a shame it cannot fit the Lotus chassis.
I happily register an interested in an overdrive, were it to be developed to fit an Elan.
On an associated matter, three or four years ago MKF Engineering in East Sussex were reported in the motoring press to be developing a 5 speed cluster to fit within the Ford 2000e gearbox casting.
It may be that this was not a viable option, as The Daily Telegraph reported in August 2018 an illegal gun factory had been found on the MKF premises!
Should it be assumed that all Elan gearbox development work has stopped at MKF?
Does anyone have an information on other locations of the development of a 5 speed Ford 2000e gearbox?
It was a 5-speed gearbox with 5th gear as 1:1 so it wasn’t an overdrive gearbox - just a close ratio box for low torque engines. Pretty much a step backwards in an Elan!
It depends on whether you’re looking for the next gear or a new set of ratios. I had two Mk III Spitfires with Laycock de Normanville overdrives and in my ignorant youth found them quirky. They did deliver over 40 mpg, though.
The available fives are not known for having great ratios. Overdrive, surely as used by Jim Clark, allows an ideal close-ratio set for maximum acceleration on the track and in the twisties (spacing between gears to match the torque curve) that is augmented by dropping the overall drive ratio to cruise quietly while still offering a downshift to third for passing. Provided that you don’t need all of the ratios in play all of the time (and it’s hard to think of a scenario where you would), it’s a very nice combination that gets you (almost) a six-speed box.
Getting into overdrive is a button press and a thunk.
Lotus typically selected overall drive ratios to allow the redline in top, making for a whiney ride on interstates (particularly in Europas where those Webers are right behind your ears!) Overdrive is a wonderful solution to this problem. Even harder to fit to a transaxle though. 
I keep wandering around industrial supply sites looking for something like “2 speed planetary gearbox”. It appears that such things are commonly used in CNC tools to transition from rough to finish rotation speeds. The ratio change there is big. But these boxes are available in lots of sizes and specifications.
I am however surfing above my pay grade on this…
John
I will second the idea that finding a good five speed gearbox is the way to go!
Fitting a Laycock overdrive to an Elan could only be done with the body off the chassis. Fitting one to the back of the gearbox would entail a new mainshaft and rear housing. Fitting to the nose of the differential might be preferable. But this simply ignores the size issue!
Laycock overdrives are very reliable-I worked through the eighties in the busiest Volvo dealership in N.America and I don’t recall one internal failure of an overdrive-but solenoids did occasionally fail. One thing a Laycock overdrive Will Not tolerate is operating in reverse-so a reverse switch is an absolute requirement.
A good five speed is the ZF S5 18/3 as fitted to many cars of the early seventies and should have been in the Elan Plus 2 I think. This box can be found in the Sunbeam Lotus, Maserati Twin Turbo, some Fiats and the Alfa Montreal plus others. Importantly, it was fitted to works Escorts for rallying so bellhousings are available.
There is small industry out there making close ratio, expensive gear sets for them but they are not required for road use. The version used in the Maserati is probably the most available since the Maseratis rusted away, however, that box has the worst ratios. The gears are pressed onto the laygear assembly and can be changed however. I acquired a box from an Alfa Montreal, quite cheaply. This has a 2.95:1 first gear but fifth is 0.87:1 which is not great as an overdrive (Montreal owners complain about fifth gear). I acquired the two gears used for the 0.80:1 fifth in a Lotus Sunbeam and fitted those during a major overhaul and the box was superb! Specialists who rebuild these boxes for racing throw away the 0.80:1 gears and I was given a set! Various gear shift locations are available. (I did not fit this in a Lotus)
I am pretty sure that Jim Clark’s “overdrive” was a 3.55:1 diff ratio!!
Just picked up on that Fiat point DavidB.
My Cortina, before I monstered it, came into my hands with a 1.8l Fiat Twin Cam and a 5 speed which,if memory serves felt like an overdrive when plopped into 5th gear.
Given the Cortina weighed a bit more than the Elan - though only marginally more than the Plus 2 - and had similar power, wheel size etc, this, the Fiat could be one way to go. Going from memory, the Fiat 'box was small and “looked” like it could fit into an Elan Chassis with minimal mods.
But that is going from memory so…
And I dunno if an overdrive unit really suits the character of the Elan…
Must buy me another Plus 2 so I can play with the number of gears I can stuff in there. 