Lotus Elan

Close ratio Bullet gearbox in a +2

PostPost by: garyeanderson » Mon Feb 27, 2012 10:25 am

vernon.taylor wrote:Salut

Saw mention of a 3.44 in an authorative book - anyone used it or heard of one?

@+

Vernon


mis print or bul!

3.9 - 39/10
3.77 - 34/9
3.55 stock - 32/9

3.54 from the 2.0 Escort 39/11

4.11 - 37/9
4.44 - 40/9 and maybe 31/7 (two different ones I believe)

and a couple others that are numerically higher

I think I am the only one that proposed having some custom sets cut in the range of 3.1, 3.22, 3.25 range and no one wanted to try them. seems they went with the 5 speeds for a lot more money. There are quite a few folks now that have 1700 engines and these just cry out for a tall rear axle ratio (in my opinion).

Capri's (German one) had 3.09, 3.22, and 3.44 but these were not the "English" axle.
More teeth are quieter and less teeth are stronger (I think).

Gary
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PostPost by: msd1107 » Mon Feb 27, 2012 4:17 pm

I vaguely remember that ratio being homologated, but have never heard of it being seen in real life. It could be 9/31 although 11/38 from the later differentials would provide the same ratio.

Does anybody remember a sedan with a 3.44 ratio? The ring gear (ring and pinion) probably could be swapped into our differential housing.

David
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PostPost by: Elan45 » Wed Feb 29, 2012 2:29 pm

When I rebuilt my S3-SS in 1985, I installed the CR (2,5:1 1st) from my early FHC and its original 3.77. I had in the car in Pittsburgh' setting of hills a few years ago and getting off line in the traffic after the Pittsburgh vintage GP was a pain. I have now obtained a 3.54 diff ratio that I plan to go into the car, so I have returned the spec to the car's original semi-close ratio box (2.9:1 1st).

BTW, I had a chance to buy an actual Bullet box about 10 years ago and it was not the same as the normal 2.5:1 Elan box. I definitely remember the syncro assemblies were quite different. I didn't get it 'cause I had to think about spending the money in tight times and two nights later, it had sold to someone else.

Roger
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'67 Elan FHC pre-airflow
'67 Elan S3 SE upgrade to 26R by Original owner
'58 Eleven S2 (ex-works)
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PostPost by: jono » Fri May 11, 2018 10:02 am

Well I have finally installed a close ratio box, very skillfully assembled by Mr Duff of this parish :D , using one of the new MFK gearsets.

I swapped back to a 3.77 diff as I was concerned about a 3.54 being too much in a the heavier +2. Initial impressions:

The tall (2.5) first is no problem at all - in fact it doesn't feel much different to the semi close with the 3.77 diff and gets off the line without undue effort. It will pull 40mph at 5,000 rpm. Letting it spin up in 1st gets you straight into the closer 2nd and 3rd gears, which is very nice

The ratios are great - they really bring the car to life. The box is more noisy that the semi close but not annoyingly so (the gears are helical but classed as 'semi-helical) - it's a Lotus after all so I don't mind!

It feels like a great upgrade, just need to do the FI now!
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PostPost by: vstibbard » Fri May 11, 2018 1:17 pm

I've owned two Elan's with the 2.5 close ratio box and 3.55 diff, a S4 SE DHC (MYJ740J Yellow with tow bar! when purchased in UK, any one know it?) and a S3SE (UK rego I'll find), both cars had no issues pulling away, were very quick and amazing to drive on a winding road. The S4SE is now in Victoria, Australia. I rebuilt the car, engine during full restoration, the big valve head "H" stamped was done by Ed Winter, did a lovely job, I've not heard any one mention him on the forum, Ken Snailham at QED did the boring and bottom end balancing and supplied all parts, I assembled it with no changes to the cams which were sprint cams and new valves and 10.3:1 comp with Strombergs, with some tuning of needles on dyno at QED after running in, it made ~127bhp with amazing economy, without the weber sound!

The S3SE coupe was modified in period had cams with similar timing to sprint but increased lift, a really nice porting job similar camp at 10.5:1, when I rebuilt it here in Australia, again it and 3.55 installed, it was very quick. This is a car I regret selling, and missed buying it again a few years ago. It now resides in Tasmania, Australia. I've the UK rego number at the shed, I'll find it a spot a picture.

I'm rebuilding a car at moment, which will have 1760 TC and planning on fitting Lotus 5 speed with 3.55, but have another 2.5 close ratio rebuilt sitting on the side just in case, as Iv'e never used the Lotus 5 speed!

I've just fitted a 2.5 close ratio into my 62 Super Seven with original Standard ten diff fitted with 4.55, and asides of the low ratio, its made a huge difference to the way the car drive, I'm now looking for a spitfire diff to replace the 4.55 with something closer to 3.9 or 3.77, and custom axles.... where does it end!

I'm a 2.5 fan in an Elan!

Cheers

V
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PostPost by: prezoom » Fri May 11, 2018 3:51 pm

i recently installed a 2.5, coupled with a 3.54 in my Zetec Plus2. Love it, though it does have a bit less acceleration than it did with the 3.77. The longer first gear more suits the car. My 64 S7 had a 2.5 with a 3.9 when I ordered it. Changed to a 4.1 for auto crossing and racing.
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PostPost by: vstibbard » Sat May 12, 2018 7:49 am

Hi Rob, would you recommend a 3.9 in the Seven for general road use and occasional track day?

V
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PostPost by: nmauduit » Sat May 12, 2018 8:21 am

vstibbard wrote:I'm rebuilding a car at moment, which will have 1760 TC and planning on fitting Lotus 5 speed with 3.55, but have another 2.5 close ratio rebuilt sitting on the side just in case, as Iv'e never used the Lotus 5 speed!


Hello Vince,

I have not used it that much yet, but my street S4se is fitted with a Lotus 5 speed and a 3.77 diff : as the 1st is even shorter than on a semi close (3.2 vs 2.97), the combined ratio would end up pretty similar. I use the fifth only on highway, and it's quite pleasurable not to have to cruise around 5000 rpm (local speed limit is 3600 rpm in 5th)... For track days, I use only 2 3 4, and it goes plenty fast enough for me (over 190km/h at 6500 rpm, and I've only taken it to windy tracks so far), so with a 3.54 you would not be speed limited in 4th in most cases and keep the 5th as an overdrive.
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PostPost by: prezoom » Sat May 12, 2018 2:58 pm

V, For road use, the revs will be the same as an original S1/S2 and the two 2 cars both used the same tire size. If I still had the seven, and it was primarily use for road use, I think I might consider a 3.54. Conditions may vary, but here in Southern California, you have to use a freeway to get anywhere, and today's traffic moves at 75mph and higher.
Rob Walker
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1964 Sabra GT
1964 Elva Mk4T Coupe (awaiting restoration)
1965 Ford Falcon Ranchero, 302,AOD,9",rack and pinion,disc,etc,etc,etc
1954 Nash Healey LeMans Coupe

Owning a Lotus will get you off the couch
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PostPost by: Mazzini » Fri May 18, 2018 6:18 pm

prezoom wrote:i recently installed a 2.5, coupled with a 3.54 in my Zetec Plus2. Love it, though it does have a bit less acceleration than it did with the 3.77. The longer first gear more suits the car. My 64 S7 had a 2.5 with a 3.9 when I ordered it. Changed to a 4.1 for auto crossing and racing.


Rob, I have a 4.11 in a S2 7, it has the original Standard axle, do you know where I could get a 3.9 or 3.7? Do Spitfire CW&P's fit?
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PostPost by: prezoom » Fri May 18, 2018 6:56 pm

The Spitfire center section will fit if you have the Triumph TR10 rear axle. The GT6 center section is the same size, but the output splines are larger, and if you have the TR10, you would have to have new axles made. I believe cars made after mine may have used an Anglia or Cortina rear axle, which would fit nicely with our Lotus stuff.
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1964 Sabra GT
1964 Elva Mk4T Coupe (awaiting restoration)
1965 Ford Falcon Ranchero, 302,AOD,9",rack and pinion,disc,etc,etc,etc
1954 Nash Healey LeMans Coupe

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PostPost by: Mazzini » Sat May 19, 2018 5:41 am

Thanks :D
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