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Virtually every car now has overdrive;it's called fifth(& sixth)gears.As for the Hobbs(there were others)hard to manufacture and not the most reliable,but that was the 50/60's.
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Over drive a totaly different concept to 5th & 6th gears you could engage O/D seamlessly in third or fouth gear whilst Accelerating giving you 6 ratio's on some cars it could be engaged on every gear
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Over drive a totaly different concept to 5th & 6th gears you could engage O/D seamlessly in third or fouth gear whilst Accelerating giving you 6 ratio's on some cars it could be engaged on every gear
Indeed Paddy Hopkirk had his adapted to work on all speeds,giving a dual ratio gearbox.
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>> Over drive a totaly different concept to 5th & 6th gears >> you could engage O/D seamlessly in third or fouth gear whilst >> Accelerating giving you 6 ratio's on some cars it could be >> engaged on every gear >> Indeed Paddy Hopkirk had his adapted to work on all speeds,giving a dual ratio gearbox.
My 1973 Triumph 2.5PI had OD that worked on second ,third and fourth gears.
It made motorway driving effortless.
(I had to replace the solenoid before it worked at all)
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Never heard of it what was it?
It was a gearbox in which each gear had it's own band-type clutch. As far as I remember it could be used in totally automatic mode or manually without having a clutch pedal to depress. David Hobbs, son of the company owner, successfully raced a Lotus Elite (number plate DAD 10) in saloon car races with this gearbox fitted in the 1960s. Some of the older Backroomers must surely remember it.
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L\'escargot.
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Whether the overdrive is automatically engaged or not,fifth and sixth gears serve the same purpose;to reduce the engine revs for a particular vehicle speed.In fact a lot of FWD four speeds have an overdrive top-usually about 0.8/1.Even the 2cv had an overdrive top.
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Ok find a well maintained Dolly sprint (Almost impossible i know) give it welly in third gear slip it into O/D at about 60 and tell me what's easier to use changing gear up to 4th then 5th ok so loads of cars have more gears but O/D was so satisfying to use
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I agree that o/d is a different concept to extra gear ratios, on the Sprint (I had one) o/d 3rd was nicely spaced between 3rd and 4th allowing swift progress on a fast A road by simply flicking o/d on and off with only the occasional use of the clutch to select 4th and/or o/d 4th.
Just think o/d on a 6 speed operating on 3rd, 4th, 5th and 6th would give 10 ratios.
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But "Laycock de Normanville" were definitely fragile;nice when the freewheel was working on them-clutchless gearchanges.
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To the person who said about it being able to engage on every gear that was usually only when the inhibitor was broken/out-of adjustment as the extra torque in 1 and 2 was usually too much for the epicyclic which had to use very small gearteeth to be able to fit in the unit.
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I think everyone's right in this debate unless we start drawing a clear distinction between
- an overdrive setting on the gearbox which will affect all gear
- overdrive gears such as 5th or 6th, whose term originates from 4th traditionally being 1:1 ratio (equidrive?) and 1-3 being underdrive gears
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Mike Farrow
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The fundamental difference is surely that an overdrive is operated simply by flicking a switch. Electrics and hydraulics do the rest.
5th and 6th gears require the use of the clutch, and then movement of the main gearlever across a now pretty crowded gate.
Models varied as to which gears it was permitted to engage overdrive on. In Volvos it is 4th only. On my Triumph 2000 it is 3rd or 4th. The TR range I think allowed OD on 2, 3 or 4.
The Laycock OD is actually very robust. Mine on the Volvo has done over 400,000 miles without any attention apart from oil changes and cleaning the filter once every 50,000 miles.
The Landrover OD was a totally different concept, and was built by Fairey, not Laycock. Although bolt-on, it worked on the ordinary gearbox principle, with gears and synchro cones. It was necessary to declutch to operate, but had the merit that it could work in any gear, high or low transfer, forward or reverse. That gave a theoretical 16 forward ratios and 4 reverse.
The Laycock OD cannot operate in reverse.
Incidentally there is no free-wheel, simply a clutchless change.
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The ones fitted to Consuls and Zephyr/Zodiacs definitely had a freewheel;there was a Swedish o/d unit fitted to 100E's-just like the Land Rover one-it was a second gearbox.
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Yes, I remember the Hobbs transmission and Ford dabbling with it, Escargot - it's that long memory again. I'm sure somewhere in the attic I have some old MotorSports with articles on it if you need a refresher.
I also remember Smith's 'iron filings' Easidrive, Manumatic and Roverdrive!
While on the subject, am I right in thinking that Honda automatics of today are different in concept from others because they are like manuals but with a clutch for each gear? Or is that just garbled misunderstanding by an ageing brain?
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When I was in the States 2 years ago for a wedding. the car hire place had unfortunately run out of big gas guzzlers, so I ended up with a Toyota Corolla saloon! :o(
It was front wheel drive and IIRC it was a 2 litre engine.
This was an automatic (4 speed I think) but it had an overdrive button on top of the gearstick!
It struck me as weird on a modern car, especially on an auto. I thought the reason was perhaps it was cheaper and less bulky to fit a 4 speed auto plus OD, rather than a 5 speed auto box. But why couldnt they get the overdrive to operate automatically?
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This was an automatic (4 speed I think) but it had an overdrive button on top of the gearstick!
>>
Many auto Toyotas and my 98 Mondeo has this as standard.
In normal driving it is hidden.
On mine it is labelled O/D and when selected it lights up O/D on the dash.
All it does is to DE-select top gear. If you are in top then you you drop down a gear. If you are in lower gears then you do not get up to top.
Most useful when rolling along in top and you want to instantly and smoothly drop to the next gear down for a bit of extra push without using the selector or stamping on the gas.
Then just touch the O/D button and the full auto box is again in play.
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My Scenic auto and now my Vitara TD Auto have the overdrive button. All it means is normal motoring is done in overdrive (4th Gear) and the button switches it into 3rd, and prevents it selecting top until you press it again. Very usefule for towing when you don't want it changing up all the time.
Ted
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I had a Volvo 244 GLT from about 1982 and I'm sure that overdrive worked on 3rd and top 4th)
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I had a Volvo 244 GLT from about 1982 and I'm sure that overdrive worked on 3rd and top 4th)
I haven't heard of that - any Volvo boxes I have seen have been top only. I'd like to have that option - may be someone added an extra inhibitor switch to make that possible.
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I had a Volvo 244 GLT from about 1982 and I'm sure that overdrive worked on 3rd and top 4th)
I know it's a very old post but they did,or at least the one I have in my garage for tidying up does.
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David Hobbs' Lotus Elite with the Mechamatic gearbox was registered 5649 UE. The Elite registered DAD 10 was a different car raced by Les Leston, and I think it had a ZF gearbox.
There were two other Elites with Mechamatic boxes, one owned by Jim Clark and the other by Stirling Moss, but these were road cars and were not raced.
My memory of the gearbox was that it had disc clutches rather than the band-type which L'escargot mentions. I think the main advantage of this transmission was the lack of the churning losses associated with conventional automatic boxes.
Incidentally David Hobbs also raced a Morris Oxford (!) and an XK140 Jag, both with Mechamatic boxes. But with these he did not have the success he achieved with the Elite - 15 wins out of 18 starts.
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LotusMike,
Thanks for setting the record straight. Obviously my memory failed me on several points. But now you've mentioned it I can remember the name Les Leston. The Hobbs gearbox first came to my notice when a friend had one fitted into his brand new 1964(?) Cortina GT. He sold the original Cortina gearbox to the Earl of Denbigh who intended it to go into a car for his son to race. (I hope I've got that last bit right!)
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L\'escargot.
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The Cortina gearbox-Four speeds-all synchro-was not as tough a box as the Anglia-Four speed-but only synchro on 2,3 & 4.They narrowed down the gears to fit the extra synchro cones.
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Standrives,manumatics and all the rest(all makes offered them for a short period) were manual g/boxes with the clutch operated by manifold vacuum.The vacuum was turned on/off by a microswitch usually on the gearknob.A restictor slowed up the engagement of the clutch but it was still a bit hit or miss.
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L'escargot,
We still haven't answered your original question, whatever happened to the Mechamatic gearbox? All I know is that it was expensive to produce, and not terribly reliable. But it was a great concept.
Did you ever drive the Cortina with the Hobbs box? If so, was it any good?
Mike
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Can't be sure, it was over 20 years ago!!
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20 yrs.??? Actually early 60's.
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LotusMike is broadly correct, I was a near neighbour of david Hobbs in Leamington Spa and both of us were in the Coventry motor inustry. He started racing his mother's Morris Oxford but got more success with a Jaguar XK140, but once the Elite arrived with the mechamatic box it was a rare event if he was beaten. The crowning glory being at the Nurburgring 1000kms where the German organisers said the car was none standard and pushed it up a class so that it had to compete with Porsches. David stuffed them anyway!!!
As I recall the gearbox was very difficult to set up on a mass production basis which was why it never got the widespread use it deserved.
Superantonio
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Known to many as the Hobbs 'Jerkamatic' gearbox
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not terribly unlike the Ro80 then...that has a microswitch in the gearlever which declutches but has a torque converter like a conventional auto
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Known to many as the Hobbs 'Jerkamatic' gearbox
In the 1960s I drove a Cortina GT which had one fitted and it was OK.
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My dad had a Wolseley 6/110 which I'm sure had an overdrive operated by a kind of pull toggle arrangement on or under the dash? Quite a jerky thing as I recall but could be smoothed out by dipping the clutch I think. Not sure, I was very young.
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Sounds like a "Laycock de Normanville".
Edited by jc2 on 31/12/2008 at 10:04
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Cat Stevens sang that didn't he?
;-)
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I had the good fortune to know John Hobbs - elder brother of David - and his father Howard Hobbs .
Howard Hobbs was a genius who designed his first gearbox at the age of eleven and his first aeroplane at the age of fourteen . Then his first automatic gearbox at a time - the late 1930's - when the British car industry had hardly become used to synchromesh .
In '56 I drove a Conquest Century fitted with a Hobbs gearbox and it was a revelation . The only way one knew it was changing gear was to see the rev counter move - absolute smoothness . This was at a time when the only auto box available was a Borg Warner which was a far more complex design and nothing like as good .
Whilst the factory could do small production runs eg for Midland Red buses and cigarette making machines - needed absolutely smooth gear changes - quantity production was another matter . This and perhaps a reluctance on the part of some car manufacturers to use a UK designed gearbox .
Whilst the BSA Group and then Westinghouse took an interest they had troubles of their own so were unable to quantity produce the gearbox for UK car firms .
I also drove a Sunbeam Rapier with a hobbs gearbox and it was just as good .
This was as good example as one could get of a first rate idea which lacked a big company to take the idea on and bring it into production .
Yours
Roger N
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I was lucky enough to buy the Jim Clark's Mechamatic Elite from Lotus. Yes, it could be jerky if not used properly but you could stick the lever in any gear and it would hold it until the Climax engine exploded (somewhere over 8,000 rpm!!!). I remember a drive to the Costa Brave along the cliffs of the coastal road. Not being used to an auto box, I started using my right foot for braking - it was a magical drive!!! I have some scanned documentation on David Hobbs' racing Elite. At the start, he would would be on the start line with the car in N and holding 5,000 rpm. As the flag dropped, he would snick it into 1st and after a moment's hesitation, the car would take off like a scalded cat with no wheel spin.
I used Silver Cities Airways as a channel ferry. They used 'over centre' straps to tie down the wheels during the trip but on the Elite, the rear half shaft was only secured with a circlip into the rear axle and a triangulated location arm. The pull snapped the circlip and 500 kms later, I heard the rear inboard disk rubbing its way through the caliper!!! A garage in France determined that my caliper wasn't standard Elite so could only removed the rear brakes for the trip back. When home, it was determined that the rear brakes where from a F.J. car - Lotus mechanics probably fitted anything they could lay their hands on when building it!!!
The car, which I sold it in 1964, was completely burned out some years later by a British serviceman in Germany after he had replace the Mechamatic with an MG g/box. However, someone recently resurrected HSH200 with a new body and a Mechamatic box ... hardly the original car.
Wasn't the Mechamatic sold to Westinghouse/A.P. and used as the automatic box for the Mini due to its low power losses?
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Wasn't the Mechamatic sold to Westinghouse/A.P. and used as the automatic box for the Mini due to its low power losses?
The Mini had a conventional torque converter auto box as did all the BMC Issigonis pattern box-in-the-sump cars. The usual planetary gea***ts, only each cluster was like a diff set with bevel gears rather than the more conventional barrel arrangement. The reason was that the thing was also shoehorned into the sump and the drive train ran around in there like a snake instead of being a conventional straight-through drive like most auto boxes. A torque converter replaced the clutch assembly and the idler gears remained. The whole arrangement ran in the engine oil as the manuals did. Unusually for automatics of the period it was a four-speed unit.
Running an automatic transmission in the sump oil meant 3000 mile oil changes and a massive oil filter, as the torque converter made short work of the long-chain molecules in the mineral oil. The sump's oil capacity was astonishing (even by BMC standards) due to the additional requirements of the torque converter heaped on top of those of the engine and box. Famous for chewing the 3rd gear band and slipping on 3rd upchanges forever after.
I ran an 1100 auto with the same arrangement for a while as a lad. It slipped on 3rd....
I agree with what's been said about overdrive units. I ran an MGB roadster for some years and that 3rd / 3rd OD pairing was gangbusters around town.
One chap I knew ran an MGB V8. He took the box and OD into one of the usual suspects for reconditioning. The whole lot was disassembled and rebuilt then, on reassembly, the two components would not mate. The torque of the V8 had deformed the casing of the OD unit and when unbolted from the box, it had "relaxed" into a new shape. He got to sit in the workshop while the transmission specialist read the riot act at him.....
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Laycocks went bust 20 years ago. I did my apprenticeship there 30 years ago
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I know this is an old post but just curious if you still have any Laycock information, especially in respect to the VLC tooling required ?
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My dad had a Wolseley 6/110 which I'm sure had an overdrive operated by a kind of pull toggle arrangement on or under the dash? Quite a jerky thing as I recall but could be smoothed out by dipping the clutch I think. Not sure, I was very young.
So did my Dad and I drove it for many years. You are correct about the toggle - a small white handle near the gear stick and under the dash. When engaged the overdrive was available on the top 2 of the 3 gears giving a "5 speed box" well ahead of its time. The five ratios were quite well spaced and the party trick was the kick down switch. By rapidly flooring (kicking) the accelerator pedal you engaged overdrive second or top - no clutch required, fast change and effectively a semi-automatic box. If in overdrive second you could then do a manual change into ordinary top and use kick down again for "fifth". In my youth I mastered the sequence as a way of achieving rapid get aways which usually surprised the opposition. Quite impressive then with what was by today's standards a low geared, underpowered brick.
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