Lotus Elan

Overdrive gearboxes

PostPost by: gordonlund » Mon Jun 11, 2007 8:31 pm

Posted: Mon Jun 11, 2007 9:27 pm Post subject:

-Overdrive Gearboxes-

A few people have looked into fitting a Laycock overdrive into an Elan. Ford fitted them to late export models of Mk2 Escorts I believe which would enable them to mate up to the Corsair 2000E box. Trouble is there is not enough room in the chassis of the Elan or +2 to take it without a lot of drastic butchering.

Has any one tried a Laycock? 8 forward and 2 reverse gears sound tempting. Apparently they could only be engaged on the top two gears in most applications.

Some gearbox specialist have in the past fitted an overdrive where the 3rd gear slot is. A bit of a compromise. Has anyone tried one of these?

I think though that for overall driveability, the 3.54 dif is by far the best and simplest option. Modern ford 5 speed box conversions may have other ideas!!

Regards

Gordon

PS I tried this thread in one of my other posts but no takers. Anyone got any views one way or the other???
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PostPost by: ianf » Mon Jun 11, 2007 9:40 pm

Gordon,

My Sprint came with a 3.55 dif' when new. The range of 3rd gear was great on A & B roads and cruising wasn't too bad. One of the dif' output shafts broke and the C&P was decreed knackered (it did hum a bit) but the re-builder fitted a 3.77! He claimed it was a 3.55 but the overall gearing is now far too low. It is surprising that 1mph/'000 can make so much difference. When I have the cash I will have a 3.4 watsit fitted. An overdrive would be great but space is obviously an issue and I can't be bothered with the re-engineering of the current 5 speed offerings which would appear to need ratio changes to match the standard box & 3.55 dif'. My annual maintenance is servicing + planned replacement of rubber bits so until I retire probably at 70 (21 years to go) the easy option will prevail.

Cheers,

Ian
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PostPost by: gordonlund » Tue Jun 12, 2007 5:40 pm

Ian,

3.54/3.55 are getting harder to find, the 3.55 was the old Ford type with a 9 tooth pinion. the 3.54 uses a 10 tooth pinion and is reputed to be stronger than the former. The 3.54 diff I aquired came out of an Escort Mexico. They range in price from ?70 to ?200 depending on who you get them off. Autojumbles are the best bet or if you know anyone who does 2 litre stock car racing they are always looking to swap a 3.77 for a 3.54. That's how I aquired mine. Stoneleigh Lotus Parts Fair in September is as good a place as ever but you have to know what you are looking for to get a good one. We got a 3.77 diff (we could not find a 3.54 unit) for ?70 from Stoneleigh last year for a friends Sprint who then took it to Stephenson Transmission Ltd in Preston Lancashire tel no 01772 723325 for a rebuild, new input seal and settup. Worth every penny, He did mine as well and no complaints. The 3.54 diff combined with the 4 speed box made my +2 a very comfortable and useable car this year touring France.

Gordon

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PostPost by: Elanintheforest » Tue Jun 12, 2007 6:35 pm

Gordon...I used to have an overdrive in my Sprint, but it was the Dolomite version :D

I never really saw the point in 3rd overdrive, although with the overdrive switch on the gear lever, you could go from 3rd O/D to 4th normal whilst pushing the switch back to non-O/D at the same time as pulling the gear lever back, if you see what I mean. It was a little slow and seemed to negate any gain from the 3rd O/D gearing, but that may just have been the Triumph box.

4th O/D was fine...as good as a 5 speed box!

My Healey had overdrive, but the switch was on the dash. So going from 3rd O/D to 4th non O/D was a deft piece of handwork...pull the gearlever back then reach for and flick the switch as you're letting the clutch out. Mind you, the acceleration on the Healey was such that it didn't make much difference whether you got 4th or 4th overdrive...it was slow, or very slightly slower.

The novelty of 3rd overdrive soon wore off on both cars, so only 4th O/D was employed for cruising. And the last point...they are blomin' heavy units. Think 5 speed box......
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PostPost by: msd1107 » Tue Jun 12, 2007 6:54 pm

Ian,

Interesting comment about being careful in the maintenance costs of your car. If you are careful, the Elan is an economical car to run. For 30 years, the overall costs on my Elan were less than the amortized costs for the sedans in the house. I even got an uprated engine, c/r gearbox, 3.55 r&p, wide wheels, etc by carefully acquiring them during maintenance periods of other components. It helps to have a skilled mechanic, who also maintained my Jaguar MK II sedan.

But the 3.55 still leaves the car under geared. For awhile I carpooled to work with a guy who had a Lamborghini. He remarked that the Elan had better acceleration than his car, but, then, I was perpetually in an under gear compared to him so when I hit the throttle at 4000 in top gear, I had better acceleration than he did in 5th.

A previous post
http://www.lotuselan.net/forums/viewtopic.php?t=13892
dealt with what r&p ratios might be needed for the Elan.

In the states we have people involved in vintage car and drag racing who could make up any r&p set we wanted, if there was sufficient interest. But any higher r&p would force the use of the wide ratio 2.97 1st, which is not too satisfactory.

People have been trying to put 5-speed transmissions in the Elan, practically from the beginning. Quite a few one-offs, but nothing commercially viable. The most recent interest seems to be centered on the T9. But the front bolt pattern is different, requiring a different bell housing. And 5th gear shift fork sits where the shift lever came down in the Lotus box, which is a bit of a problem.(!)

Alan Voight has a nice conversion with a new tail housing with good shift lever position and new bell housing. But he uses the sedan gear ratios. So you probably would go to BGH for one of their gear sets. If you can afford the cost, this would be the way to go. I have driven a T9 with modified shift lever and BGH gear set in a Lotus Elite and it is very nice.

A friend made an enquiry about the Caterham 6-speed. They are available for separate sale, but I know nothing about how they might fit into the car. And the quoted price was not too far from the combined Voight/BGH combo.

Those of you who have my gearbox spreadsheet can model the effects of all these questions. Recently, working with some other Elan owners, some questions have come up about r&p ratios and other things. So I have written a couple of simple spreadsheets, which are done but need user documentation. I will post them when that is done. Being only slightly sardonic, they continue along the path of answering questions that have not been asked and for which most people do not care about the answer. But, hey, they are fun, illuminate certain areas for me and maybe some of you.

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PostPost by: SADLOTUS » Tue Jun 12, 2007 8:49 pm

I had 3:77which broke and was temporarily followed by a 4:44 (I think) from an Anglia in the garden which while exciting from the lights was appalling over 60mph! Eventually went for an RS2000 3:54 (?) from Motoring News. Had it laced together locally and think this is a good option. (my 10cents) This is too high a ratio for rally cars so they often ditch them in favour of something lower......so... Rally mags and papers are a good place to look.
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PostPost by: tower of strength » Tue Jun 12, 2007 10:57 pm

if you google for overdrive conversions, there is an outfit who can supply a stand alone laycock overdrive, this would require a little chassis surgery to install (removeable access plate on the bottom perhaps?) and then two short prop shafts. It aint cheap though!

Off the shelf you have the Voight conversion as mentioned, or if you have a Lotus or 2nd generation (Zetec compatible) spyder chassis the MT75 can be made to fit. To do this, the chassis needs relieving either side of the gearbox near to where the gear stick sits. The MT is a bit on the tubby side at the top!!. The early spyder chassis is too tight at the start of the backbone/tunnel for this 'box. Spyder can however update your chassis.

There are a few other issues with the MT75, I'll post all of the info when I have driven my car.

The tall/short first gear ratio has been debated at great length in other threads, I believe the MT will have a 7 mph lower max speed in first over the standard 'box. I only really see this as an issue if you regularly drop into first whilst driving. Except on track days, in the dim n distant past, where first is needed for some really tight hairpins, I only use it for pulling away, there after second has always sufficed........ but that's me!!
I want fuel economy and to be able to hear my CD's when on long runs, this is my 5 speed motivation!

If you want further details of the MT75 fit, let me know.

regards

Mark
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PostPost by: garyeanderson » Wed Jun 13, 2007 12:29 am

Hi Mark

If you haven't driven an Elan with an Ultra close (2.51 1st) gearbox and a 3.55 or 3.9 for that matter, You don't know what your missing. I guess I view the Elan as a toy to play with and as such I want as much fun as I can get out of it as possible. Now if it had a .80 or .85 overdrive 5th then it would be nearly perfect. The Ultra close is out of my S2 for repairs and I have a Semi-close installed for the time being, it seems like a truck with the gear spacing in comparison. please do let us know how the mt75 works out.

Gary
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PostPost by: ncm » Wed Jun 13, 2007 3:38 pm

Hi Gordon, As you state the 3.55diff used a 9 tooth pinion but the 3.54 uses a 11 tooth pinion with a 39 tooth crown wheel. The 10 tooth pinion was used with the 39 tooth crown wheel to give the early Ford 3.90 ratio.As ever, the best way to check a ratio is to count the teeth on both the crown wheel and the pinion.
Cheers, Brian.
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PostPost by: gordonlund » Wed Jun 13, 2007 7:09 pm

Your so right Brian. I did count the teeth but have lost the bit of paper which I wrote on at the time!!!!

However, the tall diff (3.55) was offered as an optional extra on the S3 Elan SE and later on the S4 and was regarded by many as a worthwhile option. The lighter weight of the two seater Elan made the taller gearing affects virtually negligable for most people. A friend of mine had an S3 SE so equiped and he loved it. The +2 with it's extra poundage suffers a bit on Santa Pod starts but when on the move you hardly notice the differance. In fact I found it better for long distance cruising as you would expect but the intermediate gears are more uaeful for long overtaking manoeuvours, especially third gear. The original Ford Corsair 2000E 3 rail gearbox takes some beating with it's smooth switch like change (like slicing through butter)

The box in my +2 has never been stripped while in my possession and has repaid well for regular oil changes. OK you can break them if you abuse them, trying to beat the syncs, lack of maintenance and attemping to put massive amounts of tuned up (pressurised induction) power through them. I'll strip mine one day in not the too far distant future and see what wear characteristics it exhibits.

My old Cortina Mk 1 days (when they were newish) encountered stories of worn syncs causing cars to jump out of gear under hard acceleration. My experience is contrary to that which probably explains the theory of naive abuse, I'll break it, I'll mend it brigade, but is usually the next unfortunate owner of the vehicle who has to do the mending!!

A Lotus is meant to be driven smoothly and fast.

Best Regards

Gordon
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PostPost by: tower of strength » Wed Jun 13, 2007 8:09 pm

garyeanderson wrote:Hi Mark

If you haven't driven an Elan with an Ultra close (2.51 1st) gearbox and a 3.55 or 3.9 for that matter, You don't know what your missing. I guess I view the Elan as a toy to play with and as such I want as much fun as I can get out of it as possible. Now if it had a .80 or .85 overdrive 5th then it would be nearly perfect. The Ultra close is out of my S2 for repairs and I have a Semi-close installed for the time being, it seems like a truck with the gear spacing in comparison. please do let us know how the mt75 works out.

Gary


Hi Gary, I haven't as far as I'm aware experienced that combination, my mum ran a '67 plus 2 in the early 80's, followed by an S3 S/E, not sure what they had fitted, I had an S130/5 which to me seemed fine, aside from the porridge stirrer apology for a gear stick!! 5th was a godsend on the regular motorway trips I do to Preston (aprox 200mls) where the car was a lovely relaxed cruiser. Back road antics were hampered by the abysmal gear shift but 2nd and 3rd gear ratios seemed fine on the move.
The MT has similar ratios to the Lotus 5 speed but a very positive switch like gear shift.
I'll let you know how it works out!!

Regards

Mark
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PostPost by: ianf » Wed Jun 13, 2007 8:37 pm

I would be happy with a slightly higer ratio in the Elan than the old 3.55. I found first gear fine even on nasty hills and I don't think a bit higher one would be a problem. A nice round 20mph/'000 sounds about right.

Ian
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PostPost by: zeteclotus » Thu Jun 14, 2007 7:57 am

The Lotus/Maxi 5 speed only feels like a porridge stirrer if you have the early type indent springs and the rubber joint in the lever.

I fitting a MT75 in to a early spyder chassis once needed to change the chassis diagnols for flat plates notch the rear chassis by the diff to allow for a custom longer bigger diameter prop and customise the gearbox mount, modify the gear change lever, and modifi the clutch, It worked very well.
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PostPost by: worzel » Thu Jun 14, 2007 8:55 am

Hi All

Can only speak from personal experience.

About 20 odd years ago the 3.7 diff on my sprint started leaking so I thought "up the gearing and replace with a 3.54 unit". Can't say I noticed any difference I'm afraid. Still as buzzy on a motorway as ever.

So about eight years ago I switched to a Type 9 (with the lever in the right place). No comparison in terms of usability- although even 22.7 in 5th doesn't make the elan "relaxed" in any way. I use a box from a 2.8i capri so 1st in mine is 3.35 rather than the 3.65 from 1.6/2.0 engined fords.

I don't really notice the difference on take off (the 4 speed I had did have a 2.97 1st). Would most owners find this a handicap- sorry but I think this is a lot of hot air. Do owners really, as a habit, drag start every time from rest. Probably not. The tone of complaints about gearing over the years would suggest that the biggest gripe is a too low top and owners are looking for easier cruising. Correct me on this point but didn't the 5 speed plus 2 models have a 3.30 1st. I don't seem to recall testers complaining about the gearing back then. In fact what is "lost" on 1st is gained on 2/3- mine runs to 65 or so in 2nd and 95+ in 3rd.

Would I ever go back to the original box?. Sorry if I upset anybody but there is no comparison between a std elan and one with this mod done correctly. If you use the car as a weekend occasional toy then fine but I still like to cover the miles and better gearing is a must for me. This is the biggest improvement I've ever done on this car (and I've done a few over the 29 years I've had it).

Regards

John
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PostPost by: iain.hamlton » Thu Jun 14, 2007 10:00 am

I met a chap with a stand at the Beaulieu Autojumble event the year before last. He had developed a remote housing for overdrives. I have looked but i cannot find his conatct details.

Anyway, our idea was to place the overdrive at the back, directly fitted to the diff pinion flange. I measured it up and think there is enough room. The overdrive man was happy to make the special housing, but I am afraid I could not justify the trouble of getting the propshaft shortened etc. and the cost.

best regards, iain
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