Lotus Elan

6 speed gearbox for the Elan

PostPost by: pauljones » Wed Jul 01, 2009 6:45 pm

how about a lotus 2.2ltr twincam with its 5 speed (lotus type)
Kick the tyres and light them fires...!!!!!!!
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PostPost by: garyeanderson » Wed Jul 01, 2009 7:42 pm

paddy wrote:Was the leg cheaper if you bought it as a kit?

Paddy


$10k to $12k u.s.d. total 6 years ago and I paid $4K of that out of pocket, all custom coachwork no kit version.
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PostPost by: blackandgold » Fri Jul 03, 2009 11:28 am

not yuc, just easy...
Lighter too.

Gary[/quote]

Gary I am in the same situation having lost my lower left leg 33 year ago in a motorcycle accident

However I have always had manual cars and never had any problems with clutches even heavy duty ones

What componants are you using? I have a flex foot with silicon liner and prefer a foam cover rather than the
exposed look in your picture

As far as been lighter I am told they weigh the same as a normal leg
Mark

1973 +2 S130 with BDA
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PostPost by: garyeanderson » Fri Jul 03, 2009 12:10 pm

At the time of the attemped C4 swap, I had been using wool stump socks with a foam liner with a sach foot for 25 years. That was part of the reason for the c4 automatic substitution. Have moved on to gel liners and things are much better. I have put a few miles on manual boxes, probably more than half of the 700,000 miles have been with a 4 speed manual.

p.s. - the foam is extra weight, besides the looks from the kids when they see Beauregard and I walking down Main Street in Nantucket are priceless.
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part kit.jpg and
Parts kit, broken composite toe and wornout bushing. reminds me of some of the Elan I have worked on.
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PostPost by: john.p.clegg » Fri Jul 03, 2009 2:47 pm

I hope we're not going to get on that trunnion thing "do you use oil or grease"....

John :wink:
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PostPost by: garyeanderson » Fri Jul 03, 2009 3:11 pm

john.p.clegg wrote:I hope we're not going to get on that trunnion thing "do you use oil or grease"....

John :wink:

No Lube,
well, maybe a dip in salt water and a quick rinse in fresh...

Hey!

Was someone talking about a 6 speed box for the Elan? :)
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PostPost by: MintSprint » Fri Jul 03, 2009 4:37 pm

pauljones915 wrote:how about a lotus 2.2ltr twincam with its 5 speed (lotus type)


The 5 speed used with the 2.2 litre Lotus Twincam is essentially the same gearbox as was used with the 5-speed Elan +2; the good news therefore, is that there's a readily available conversion for anyone who wants it. The bad news is, it's rubbish. :wink:
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PostPost by: john.p.clegg » Fri Jul 03, 2009 9:14 pm

No,it's not rubbish..

and...

No it's not an easy conversion....I spent lots of time and a little money moving the gear lever,shortening to ford length and trying to fit the tail section into the chassis....it won't fit.


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PostPost by: msd1107 » Sun Jul 05, 2009 12:31 am

Well, there has been a lull in the amount of stultifying numerical detail in this 6-speed project. So I thought I would rev up everybody?s heartbeat with some more stimulating numerical nuggets.

A previous post gave a numerical analysis of five 6-speed transmission ratio sets uncovered by Gary, plus a hypothetical set proposed by Bill.

This post will include the corresponding data for the two standard 4-speed Lotus transmission sets, plus a verbal description as to how these different ratio sets might feel if someone were to drive each set back-to-back.

Lotus CR 2.51 1st, 4th direct,
Gb ratio % diff speed...diff....err..FoM=99.8
2.510....53.4...047.9..25.6..00.0...51.9 at 7,000
1.636....33.0...073.5..24.2..00.0
1.231....23.1...097.7..22.6..00.0
1.000............120.3

Lotus ?Mid-close? 2.97 1st, 4th direct,
Gb ratio % diff speed...diff....err..FoM=97.5
2.972....47.9...040.5..19.5..00.1
2.010....43.9...059.8..26.3..00.3
1.397....39.7...086.1..34.2..00.0
1.000............120.3

Now, let?s take a pretend drive in 8 cars with these 8 different gearboxes. Back-to-back drives allow for the evaluation of subtle differences between gearboxes that appear to be close together and that might not be so noticeable individually. But the wide range of gearboxes makes differences quite noticeable. I will proceed from the highest geared 1st speed to the lowest geared 1st speed.

Lotus CR.

On startup, the acceleration feels soft due to the high gearing (50+ if you go to 7000). 1st to 2nd feels medium close, basically because the gearing is high (in many cars, this is similar to 2nd). 2nd to 3rd feels a little closer, and 3rd to 4th feels closer still. Looking at the speed difference between gears shows why. The speed difference decreases for each gear, giving the impression of closer gearing. Notice the FoM of 99.8, as close to perfect as you are likely to see.

Bill?s hypothetical 2.65 1st, 4th direct, OD on 5th, 6th.

Startup is easier, due to the lower 2.65 1st. 1st to 2nd and 2nd to 3rd feel quite similar, because the mph drops between gears are quite similar. 3rd to 4th feels a little wider, since the CR has a decreasing mph gap between gears and this gearbox has a constant gap. 4th to 5th feels the same, and a car with the proper differential ratio and engine tune should be able to pull max revs in 5th. 5th to 6th feels the same drop, and 6th is a true overdrive. Many of you are running around 4800 rpm at 80 mph. This setup shows just over 3000 rpm

Well, it is not too likely we will get a new gear set cut, and even less likely re-engineer the shift linkage for 4th direct. So I generated a new gearbox with the same overall ratio between 1st and 6th, but with 5th direct. This came out with 3.205, 2.042, 1.528, 1.208, 1.000, and 0.855 ratios and a FoM of 94.2. Using a pinion and ring gear of 11:33 produces speeds in gear very close to the previous gear set and a 9:32 3.55 differential. 10:32 would be equivalent to a 3.77, and 10:33 would be equivalent to 3.90.

Lotus ?Mid-close? ratio 2.97 1st, 4th direct.

The so-called ?mid-close? ratio is actually a sedan ratio set. Startup is much easier in 1st since the Elan is quite a bit lighter than the corresponding sedan. 1st to 2nd feels closer than the previous two gear sets. It is in an absolute sense (% drop of 47.9% vs 56.9% and 53.4%) but the speeds are lower, so the mph difference is less also (19.5 mph vs 25.8 and 25.6). 2nd to 3rd feels a little wider (26.3 mph difference vs 24.6 and 24.2). The 3rd to 4th shift feels quite wide, both percentage wise (39.7% vs 26.5% and 23.1%) and speed difference (34.2 mph vs 25.2 and 22.6). The FoM is an excellent 97.5.

TRD 33030-SE100 3.106 1st, 0.869 6th.

1st is lower than the ?mid-close? set. Running up and down through the gears you will get the feeling that 1st to 2nd and 5th to 6th are slightly closer than the other ratios and 3rd to 4th is slightly wider. See this in the speed difference column where 1st to 2nd and 5th to 6th are less than the other ratio differences and 3rd to 4th is greater. See this also in the err column, where the high error figure accurately predicts problem in the staging of that ratio pair. Also, the FoM of ?21.9 indicates problems in the staging of the ratios.

S15 3.626 1st, 0.767 6th.

The 3.626 1st gear is markedly lower than the previous gear sets and is hardly more than a startup gear, getting only to 33.2 mph. The 5th to 6th ratio gap is very wide for the top gear pair. This is responsible for the FoM of ?308.6. Considering only the first five ratios produces a FoM of 72.8 and feels pretty good. A 0.85 OD 6th gear would produce a FoM of 85.1

MX-5 3.76 1st, 0.843 6th

1st is even lower than the S15 gear set, getting only to 32.0 mph. Shifting up and down, the only thing noticed is that 5th to 6th seems slightly wider than the other gears. See this in the speed difference column, and also this shows in the FoM err column.

RX-8 3.76 1st, 0.843 6th

1st, 2nd, 3rd, 5th, and 6th are the same as the MX-5. 1st again is only a startup gear. Just changing 4th brings the FoM down from 68.5 to ?156.7, indicating some kind of problem in the staging of the ratios. See it in the speed difference column where 3rd to 4th is wide at 28.2 mph, and 4th to 5th is close at 18.9 mph. I wonder why they did this.

SXE-10 3.874 1st, 0.869 6th

Here 1st feels even lower and more useless, getting only to 31.0 mph. To compound the problem, the 1st to 2nd percentage drop of 78.1% is extremely wide. Shifting from 1st to 2nd bogs the engine unless you rev the h... out of the engine in 1st gear. In addition, the 3rd to 4th and 5th to 6th feel closer than the other shifts, which is reflected in the speed difference column and also the FoM errror column and also reflected in the FoM of ?51.6.

So there it is, guys. We use an off the shelf sedan gear set and we suffer the consequences. Bolt up an optimum set, the installation goes more smoothly since the shafts hook up to our existing clutch and driveshaft and the driving experience is more pleasurable. For those who are doubtful as to being able to detect these differences, you only need to do a back-to-back once to be convinced. But, hey, it is your car, and your money.

Well, the ribs have been on the barbecue for hours, and the guests are due. I better get the table set, the champagne out, the wine decanted, and do something useful today! Happy Fourth to everybody.

David
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PostPost by: GrUmPyBoDgEr » Sun Jul 05, 2009 9:07 am

Hi David,

that little lot was an interesting read.
Thanks very much.

Cheers
John
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Editor: On Sunday morning, February 8th 2015, Derek "John" Pelly AKA GrumpyBodger passed away genuinely peacefully at Weston Hospicecare, Weston Super Mare. He will be missed.
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PostPost by: Verve » Sun Jul 05, 2009 10:05 am

I Think David Deserves an Award ; ) !
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PostPost by: msd1107 » Sun Jul 05, 2009 5:21 pm

Verve,

Thank you. For my award I'll take a 6-speed set like Bill proposed as modified for direct 5th and a 11:33 r&p. I'll pay just so we have one customer.

John,

Thanks for the comments. As soon as the first post came, I called Vincent. No response. I sent him an extensive email, volunteering software and any other assistance. No response.

I guess they are busy spannering away to get a lash-up finished. Reading the posts, this is already a 2 year old project that is not finished. The Elan conversion is more difficult than their original conversion project.

One thing to consider is that our Elans are 40 years old, and we have to consider the maintenance aspects of the conversion over the next generation. A conversion with a lot of non-standard pieces does not make me feel comfortable. A direct bolt in (plug-n-play) would make me feel a lot better.

I don't think Gary, myself, or many others would trade our 2.51 CR transmission for the current project.

Let's hope for the best.

David
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PostPost by: GrUmPyBoDgEr » Sun Jul 05, 2009 6:21 pm

msd1107 wrote:Verve,

Thank you. For my award I'll take a 6-speed set like Bill proposed as modified for direct 5th and a 11:33 r&p. I'll pay just so we have one customer.

John,

Thanks for the comments. As soon as the first post came, I called Vincent. No response. I sent him an extensive email, volunteering software and any other assistance. No response.

I guess they are busy spannering away to get a lash-up finished. Reading the posts, this is already a 2 year old project that is not finished. The Elan conversion is more difficult than their original conversion project.

One thing to consider is that our Elans are 40 years old, and we have to consider the maintenance aspects of the conversion over the next generation. A conversion with a lot of non-standard pieces does not make me feel comfortable. A direct bolt in (plug-n-play) would make me feel a lot better.

I don't think Gary, myself, or many others would trade our 2.51 CR transmission for the current project.

Let's hope for the best.

David
1968 36/7988


Hi David,

You may recall that I've put a load of "non-standard parts" into/onto my S4.
I didn't give any of them a second thought because all of the changes are reversible.
If that 6 speeder has correct output splines, the gear lever is in the right place & maybe a mechanical speedo drive it'll be on my wish list.
That's not to say that I would be able to afford one; rather like the Ferarri F40 that I lust after :roll:

Cheers
John
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Editor: On Sunday morning, February 8th 2015, Derek "John" Pelly AKA GrumpyBodger passed away genuinely peacefully at Weston Hospicecare, Weston Super Mare. He will be missed.
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PostPost by: msd1107 » Sun Jul 05, 2009 8:35 pm

David wrote
For my award I'll take a 6-speed set like Bill proposed as modified for direct 5th and a 11:33 r&p. I'll pay just so we have one customer.


John wrote
If that 6 speeder has correct output splines, the gear lever is in the right place & maybe a mechanical speedo drive it'll be on my wish list.


Some things that add to or complicate any conversion effort.

If the standard output shaft is used, a new yoke and probably drive shaft is required. To use the standard Lotus components, a new ouput shaft is needed. The cost of a new output shaft probably exceeds that of a new yoke and drive shaft as well as requiring disassembly/reassembly of the gearbox.

If the standard input shaft is retained, it probably needs machining to proper length and it needs a new clutch at best. If a new input shaft is used, whatever clutch and flywheel the owner has can be retained. The cost of a new input shaft probably exceeds that of machining the existing shaft to length and a new clutch.

The gearbox needs to have the mounting bolt pattern converted to the Cortina bolt pattern. This may require welding and drilling. Otherwise, the conversion needs a bell housing that bolts to the gearbox on one end and to the Ford block on the other. Lotus owners may have the standard iron bell, or the optional aluminum or magnesium bell. The welding and drilling cost is probably less than a new bell housing, as well as allowing the owner to retain their existing components.

A new gearbox to frame mmounting bracket is needed. No difference between approaches.

The gearbox needs a right angle drive for the speedometer cable. In addition, appropriate speedometer drive gears need to be sourced. Otherwise, the owner needs to send their speedometer into a rebuild service to get new speedometer gears installed. The cost of a speedometer rebuild far exceeds that of new speedometer drive gears, and that cost is born by the owner in addition to the cost of the gearbox.

The shift lever needs to come up in roughly the standard location. Otherwise, the owner is faced with hacking up their frame, as was described in the referenced post.

Wiring to hook up to the reverse light switch.

If new input and output shafts are done, it provides the incentive to get a proper set of ratios done at the same time. This is a major cost penalty, but, as mentioned, a good percentage of our members probably will pass on this conversion given a standard sedan based ratio set.

We can pontificate as much as we want. Until Vincent comes up with a product all this is useless.

David
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PostPost by: garyeanderson » Sat Aug 01, 2009 11:12 pm

August started today, anyone had an update from Vincent?

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