Lotus Elan

5 Speed Box or 3:55 diff

PostPost by: mark030358 » Sat May 02, 2020 5:20 pm

So I'm considering a Swiss Alps tour,( well a bit more than that) circa 3500 miles in my Elan in the next year or so, virus notwithstanding. I have done two tours in my Exige which have been fantastic, so now is the Elan's turn.

The problem is a four speed box I think will just be too painful with the standard diff, so I'm considering buying and fitting a Lotus 5 speed box. However a friend of mine suggested to just change the diff, something which I hadn't considered.

For sure getting a diff and fitting it will be far easier and cheaper than a Lotus 5 speed box. So I was wondering if anyone can shed any light on what its like to drive with an Elan 3:55 diff.

For instance...
i) Does the car pull OK, or won't it pull the skin off a rice pudding.
ii)RPM's and cruising speeds. Has anyone any figures of speed/rpm for the box vs Diff?
iii) How will the car cope with long and in some cases sustained mountain pass climbs, i.e. will it be low gear all the way?

All opinions welcome.

cheers
mark

ps if anyone has a diff for sale PM me please.
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PostPost by: elansprint71 » Sat May 02, 2020 5:31 pm

I've got a 3.54 diff in my Sprint, which has about the standard power output, it also has Mick Miller Drive-shafts; you do have to slip the clutch just a bit more than with the previous 3.77 diff but, other than that it's fine.

I've only driven cars with the Maxi gearbox a couple of times and have to say it wasn't anywhere as "sweet" as the Corsair 2000E box we know and love. :)
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PostPost by: Mazzini » Sat May 02, 2020 6:10 pm

I have a S2 that was fitted with a Voigt 5 speed box and a 3.7 diff, Nick Stagg did the head (Q420 cams), it also had a few TTR go faster bits. It would easily cruise at 80/90mph in fifth, but there was still enough umph to pass traffic without changing down. I felt the car was too much like a modern car and I've converted it back to 1965 spec. I think it could have run a 3.5 without issue, but then the S2 is a lot lighter than later cars. I must be the only person to go from CV joints to Rotoflex couplings and from a 3.7 back to a 3.9.

I also have an S3 S/E with a close ratio box, 3.5 diff and a Nick Stagg head (Q420 cams). The off the line grunt is lost, but the motor doesn't have any issues with the high first gear. If you read period road tests of the Elans the journalists reckon that this was the best set up, but they wanted a 5 speed box. It's a lot of fun.

My Sprint currently has a 3.5 diff and the 2000E box, I'm going to fit a Lotus 5 speed box shortly. I reckon the reason Lotus fitted the 3.7 to the +2S 130/5 was because of the cars weight, a 3.5 should be fine in an Elan.

I have a lot of respect for people that can do long distances in a drop top, I feel the need for air conditioning in high summer...Europe can get up to 40C and above on a regular basis. I now understand why Jaguar fitted A/C to convertible E-types.
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PostPost by: 69S4 » Sat May 02, 2020 6:40 pm

When I took my fhc down to the Alps a couple of years back it was in the low 40’sC inside on the way down - and that with the windows open. Air con would have been very welcome.
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PostPost by: quaybook » Sat May 02, 2020 8:25 pm

Hi
My S2 has a Sprint spec engine, 4 speed box and a 3.55 diff. I don't find the diff too tall, about 3500 rpm at 70 mph which is busy but, in my view, just about ok for cruising. Sure, the 3.55 diff blunts the car's speed off the line, but it is still very sprightly for a 1966 car. I have CV joint driveshafts, but if you still have Rotaflex joints a heavy foot off the line is ill advised anyway I think!
I reckon it will be easier to find a Ford 3.54 diff than the Lotus 3.55, and the Ford is stronger and an identical fit.
I'd like a 5 speed box for modern road conditions, but I understand the Lotus 5 speed is not a good change and can be troublesome. The Voigt box sounds good, but requires chassis alterations I believe and I'm not too keen on that idea. I think Kelvedon are planning a 5 speed box, which may well be the best bet if and when available.

Good luck with the long trip. I love driving my Elan and have taken it to central France and Spa in Belgium, but long runs on modern main roads are just not what the car is made for, so the long ones for me have to be taken in short bites, using the French 'D' roads or equivalent.

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PostPost by: john.p.clegg » Sat May 02, 2020 8:35 pm

The Lotus Elan is a 60's sports car , I went down to Sicily with a friend for a three week road trip and with the 5 speed maxi box,it was a breeze , retaining the nice Elan first four cogs and a fifth for motorway cruising...wouldn't even of considered it in a four speeder..

The maxi derived 5 speed box is not snickety-snick like a ford, but the other options??

John ;-)
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PostPost by: greg40green » Sat May 02, 2020 8:39 pm

I have run 3.7's and 3.5 diff's with my standard tuned Lotus TC's in the Elan's and no you don't have to start slipping the clutch with a 3.5 to pull away for everyday road use, this is a myth .
The 3.5 diff is not a problem and is a better option than a 3.7 for motor way driving .
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PostPost by: mbell » Sat May 02, 2020 9:15 pm

john.p.clegg wrote:The maxi derived 5 speed box is not snickety-snick like a ford, but the other options??


Personally I would definitely describe my lotus 5 speed as a snickety-snick box. But I believe it got a recent rebuild and is very much on the better end of gear change feel for the 5 speed.

I've only done a couple of laps of small car park in a 4 speed, 1st/2nd changes. I was expecting it to be noticably better than mine but I didn't find it so, my lasting impression was it had a much longer throw.

I believe my car (+2S130/5) has a 3.55 diff in it and have no problems getting it off the line, wouldn't describe it as a rocket of the line, but it's fine.

I wouldn't describe the 5 speed box as robust but given the likely usage of the cars these days I think it's fine if you get one in good nick. Most of the niggles can be fixed with the box, major issues seem to be weak input bearings that can be up rated and weak synchro's. If you get one you'll want to go through it carefully before fitting to the car.
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PostPost by: Foxie » Sat May 02, 2020 9:48 pm

mark030358 wrote:So I'm considering a Swiss Alps tour,( well a bit more than that) circa 3500 miles in my Elan in the next year or so, virus notwithstanding. I have done two tours in my Exige which have been fantastic, so now is the Elan's turn.

The problem is a four speed box I think will just be too painful with the standard diff, so I'm considering buying and fitting a Lotus 5 speed box. However a friend of mine suggested to just change the diff, something which I hadn't considered.

For sure getting a diff and fitting it will be far easier and cheaper than a Lotus 5 speed box. So I was wondering if anyone can shed any light on what its like to drive with an Elan 3:55 diff.

cheers
mark


I've done nearly all of the high Alpine passes over the past 20 years, some of them several times, in my Plus 2, with 3.77 and 3.9 diffs. I wouldn't recommend doing them with a 3.55.

Also, make sure you have a good modern fan, with manual override. A lot of the climbs will be at slower speeds and full throttle. The first time I went over the St Gotthard I had to stop for 20 minutes every 20 minutes to allow the engine to cool off. I fitted 2 x 10" fans after that.

I have an original Lotus 5 speed gearbox, unused since it was rebuilt by my good friend Alan Voigts, which I hope to put on eBay soon. I'll post here when I do.

:)
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PostPost by: vstibbard » Sat May 02, 2020 10:54 pm

My S3 SE Elan had a close ratio (2.5:1 first) gearset and 3.55 and was a a pleasure to drive, it had wide radiator and no overheating issues here in Australia, it was lovely to cruise and with close ratio gears sensational in the twisty stuff.

the Elan is significantly lighter than a +2 so keep in mind when considering advice.

Highly recommend it as a set up for cruise and fun.

Vaughan
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PostPost by: Davidb » Sun May 03, 2020 12:36 am

Absolutely agree with all the foregoing - I have a close ratio box and the 3.54 (from Burtons)-I cannot imagine going on a long road trip with a lower final drive ratio. Make sure you have a full size radiator-not the small S4 one though.

Ps There is a LOT of discussion on this on the forum
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PostPost by: Foxie » Sun May 03, 2020 1:37 am

Foxie wrote:
I've done nearly all of the high Alpine passes over the past 20 years, some of them several times, in my Plus 2, with 3.77 and 3.9 diffs. I wouldn't recommend doing them with a 3.55.


I forgot to say I was running those diffs with a Lotus 5-speed and later with a Voigts T9 5 speed gearbox. :oops:
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PostPost by: vstibbard » Sun May 03, 2020 1:48 am

Unless you want to run autoroutes and motorways, the 3.55 will be perfect.

As a younger man.... 35 years ago, I used to regularly make the trip from Camberwell in SE London to Moissac about 70km north of Toulouse, we would leave on 2am cross channel ferry to Calais and be in Moissac for 6-7pm with only a brief stop for breakfast and lunch enroute, with two drivers, top down and a route perfected over years by my friends parents who owned the house in Moissac and we stayed on back roads that by passed bigger towns and occasionally Napoleons tree lined routes... At the time I owned my first Elan, an S4 SE with semi close and 3.55, we would cruise at 60-75mph, pass anything we caught quickly and averaged in mid 30's mpg, always FUN drive.

It's all about averages, we could do the same trip in MkII Spitfire 1300 with OD and it took apex and longer by comparison, the over taking was a little more desperate though!!!

We also did the annual LeMans trip for the 24 hour in convoy with soej quick cars and never felt undergunned on the same types of roads.

Cheers

V
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PostPost by: geni » Sun May 03, 2020 7:56 am

If a specialist could tell us the method to recognize the existing assembly! on the car, detailing the subject.
Often we ignore the one in place!
I'm sure it will make want to check existing installation.
Thank you to those who are looking for the sharing effort.
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PostPost by: nmauduit » Sun May 03, 2020 10:00 am

geni wrote:If a specialist could tell us the method to recognize the existing assembly! on the car, detailing the subject.
Often we ignore the one in place!
I'm sure it will make want to check existing installation.
Thank you to those who are looking for the sharing effort.


What assembly are you talking about (I suppose you are considering the case of purchasing a car of unknown characteristics)? the 4 speed gearbox has a cast iron roundish case, very distinctive from the boxy alloy one of the Lotus 5 speed gearbox (there are tons of photos on the forum), a glimpse under the car is enough to find out. As for the diff ratio, to measure what is actually on a car one just needs to roll it a few meters in 4th gear (after taking the plugs off for easier pushing) with a piece of tape on the propshaft and on a rear wheel, then counting the number of turns (e.g. 3.55 propshafts turns for one wheel complete rotation, or say 7 for 2 etc).
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