Lotus Elan

3.55 gears

PostPost by: Lotus 50 » Wed Jul 27, 2016 12:39 am

Has anyone put 3.55 gears in a Plus 2 for more relaxed highway use?
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PostPost by: john.p.clegg » Wed Jul 27, 2016 5:18 am

I take it you mean in the diff...thought about it , but doesn't help in slow moving traffic, ( we are in the 21st Century here in the U.K. ) but fitting a five speed box helps in both directions ( lower first,higher fifth..)

Gear-change may not be as good , will knock milliseconds off your lap times , that is if you go racing...


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PostPost by: Sea Ranch » Wed Jul 27, 2016 5:46 am

Lots of discussion & threads devoted to this topic. Most seem to think it's desirable these days. However, I would echo John's concern about the resulting taller low gear making it more difficult to keep the clutch out when creeping along in traffic.

Having said that, I have not read one poster who regrets going to the lower (3.55 or 3.51) diff ratio.

YMMV

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PostPost by: JJDraper » Wed Jul 27, 2016 9:01 am

I have tried a 3.55 unit with my 4 speed+2 and the results were as expected. More relaxed cruising and it made the long motorway trips easier. The flip side is that day to day use was harder; slightly trickier getaway at the lights/T junctions and a tendency to go faster than perhaps you should on motorways. On balance the cons were at slow speed and maneuvering and it just seemed to blunt the perkiness of the car. The pros were more relaxed cruising. The worst episode was on holiday in Italy, where the poor +2 with the 3.55 diff had real difficulty getting up some of the tight, twisty mountain passes in rural areas and I had to take a second run-up to get up some hairpin bends. Main roads were fine. When a bend is really tight, you had to slow down and it had real difficulty getting going again on the steep slopes. Currently running a 3.77, with the 3.55 on the shelf in case I change my mind.

Perhaps that 6 speed conversion would be a better compromise....

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PostPost by: Elanintheforest » Wed Jul 27, 2016 9:24 am

My BDA Plus 2 has a 3.55 fitted, and does bog a little when starting off, but once on the move it's fine. If I keep the car I will put a 3.9 diff in and a 5 speed box to improve the getting-going acceleration and cruising comfort, although it is pretty noisy in the car at anything over 3000 rpm!
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PostPost by: rgh0 » Wed Jul 27, 2016 10:29 am

The 3.55 diff with the Lotus 5 speed gear box with its higher numerical first gear ratio is ideal as the 5th with a 0.8 overdrive ratio and the 3.55 diff is great for highway cruising and the lower first gear great for steep hills and starting when heavily loaded.

With a 4 speed standard semi close ratio box I would probably use a 3.77 diff in a plus 2 unless I mainly used it for high speed cruising in which case I would go for the 3.55

cheers
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PostPost by: Briggs1 » Wed Jul 27, 2016 5:24 pm

I have the 3.55 in my Plus 2, exactly for the "plus" reasons mentioned.

Getting off start around town takes some throttle blip to get moving. I have gotten used to it but would prefer to not have to deal with it

60 mph is at about 3500 rpm from memory - quiet it is not. Not sure how negative the trade off is to go to a more "around town" ratio.

a five speed trans - now that would be the solution......
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PostPost by: mbell » Wed Jul 27, 2016 5:52 pm

rgh0 wrote:The 3.55 diff with the Lotus 5 speed gear box with its higher numerical first gear ratio is ideal as the 5th with a 0.8 overdrive ratio and the 3.55 diff is great for highway cruising and the lower first gear great for steep hills and starting when heavily loaded.


I have this setup and agree it seem a good balanced setup.
'73 +2 130/5 RHD, now on the road and very slowly rolling though a "restoration"
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PostPost by: david.g.chapman » Wed Jul 27, 2016 6:25 pm

I have kept my 4 speed box and 3.77 diff in my +2, but have modified the exhaust by adding a straight through box in before the back box. I have also added a baffle in the outlet pipe- just a closed section of smaller diameter pipe with holes drilled in it. The closed end faces the rear end of the exhaust.

I do not detect any loss of power and the car is quieter at 4000 rpm in 4th - certainly not wearing IMHO. This might be another way forward to consider.....

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PostPost by: Sea Ranch » Wed Jul 27, 2016 10:06 pm

Indeed, Dave. And I, for one, would like to see any pix, diagrams, webpages, etc. with your baffling/exhaust tips. Or any other tips on making the exhaust note quieter. :mrgreen:

Thanks,

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PostPost by: Lotus 50 » Thu Jul 28, 2016 1:14 am

Thanks. I got clear direction from the above. No change in gears for me.

More detail? I live in Windsor ON, near Detroit and we have a summer house 500 km (300 miles) away, north of Toronto. I keep the car in Windsor in the winter. The car is up north from late May to September. I do the highway drive to the summer place each spring and then back in the fall and it is frankly no fun.Also driving to LOGs is not pleasant either. I seldom go to LOGs, but maybe I'd go to more if the drive was nicer.

Yesterday, I was buying a part from RD Enterprises and I saw 3.55 gears advertised on their website. Hmm...

My Plus 2 is a delight at the summer place. Secondary roads, hills, not much traffic. I think I'd enjoy it a lot less with 3.55 gears for most of my use. 5 years until I retire and move there, so 10 or 11 more of the long drives.
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PostPost by: Sea Ranch » Thu Jul 28, 2016 4:01 am

Dear Mr. Chapman,

Some 50 years on now, and honestly the only thing missing from your marvelous Plus 2 is an extra gear. Otherwise, perfect.

Best regards,

Type 50 fans.

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PostPost by: john.p.clegg » Thu Jul 28, 2016 5:19 am

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PostPost by: AdrianSi » Thu Jul 28, 2016 6:31 am

With regards to the responses above, what diameter/profile tyres are people running?

Mine has 165/70/13's (which I like the look of), so I'm noticing cruising speeds being even higher. I would imagine that it wouldn't do much more than 100mph flat out. So I have been considering the down gearing of the diff.
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PostPost by: jimj » Thu Jul 28, 2016 8:33 am

As you may know; I have a Voight 5 speed with 3.55 diff. in the S3 Elan so motorway driving is much more relaxed. If anything first gear is a bit low. I have an original spec. Sprint too with the 4 speed and 3.77 diff. Were I not determined to keep everything ex-factory (even including rotoflexes), I`d definitely fit a 3.55 diff. I know the +2 is a little heavier but I wouldn`t think first gear would be too high.
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