5-Speed for North America

[garyeanderson]

First off, no one has decided on any ratio yet, I was using the .80 overdrive ratio as an example. I just happened to come out to 3.12 (.80 x 3.9) which is the S2 standard diff ratio (worst case) times a common overdrive ratio. I don't think you could make a 3.12 with the number of teeth on a pinion. Common number of teeth for the pinion range from (I'm guessing here) 8 to as many as 13. Two of ratios in the elan have 9 teeth pinions (3.77 and 3.55) and ring gears of 34 and 32 teeth respectively, the 3.9 is probably 10 and 39, there is an error in the manual on this. Other ratios that I know exist from other makes are 3.08, 3.22, 3.25, 3.36, 3.44 and these are the ones that I would think would be in the range for selection. This is not a pick your ratio type of deal, we would all have to agree on one and have that built. I have a 3.55 in my Elan now, I also am running 20 inch tall tires so top speed is the same as a standard S2 with the 3.9 diff and the taller 155 tires. I am a little biased to the 3.22 or so.

Andy, I have the 1700cc engine and I feel I could pull any of the ratios listed. I had a ultra close gearbox in my Elan and swaped it for a semi close when I put the 3.55 in, I was worried about 1st gear being two tall. What I found was I don't think it mattered. Ford made a semi close for the Capri or Cortina that has a 3.65 first and second was 1.97 third was 1.39 so there is an option for someone that that has a heavier plus 2 or lives in an area where they have to stop and start on steep hills.
A 5 speed would be great but no one has a Lotus solution (Cheap or inexpensive) for that problem. I don't think this will be inexpensive either but if you can do it all your self and the numbers proposed by Rob come out on the low side (aka $800) then bearings and seal crush sleeve etc. will be another couple hundred, good time to install that quaife torsen limited slip... its going to add up and I don't want to leed any one on about it. What it will be, is a good ratio for the highway that is totally reversable and can be installed or removed in a day without making modifications to make it fit of leaving tell tails of it ever being there in the first place if its ever removed

Gary.

[mac5777]

Gary,
Thanks for the additional information, I understand the choices better now.
If you or Rob are looking for a vote for a "purchasing group", I would be OK with 3.22, 3.25 or a 3.36.
I will check with the local elan owners for their interest and get their votes.

Thanks again, Sarto

[DJThom]

I contacted the Isuzu transmission rebuilder at the link posted earlier in this thread. They were not able to tell me specifically what the gear ratios were in the MSG-5K, but did state that all of these boxes were identically geared whether in the Impulse, i-mark or pickup.

So I guess I need to see one at the wrecker and eyeball the ratios. That won't be for a few weeks...

[garyeanderson]

Hi Darren

I found this page on the Isuzu Impulse, it lists two sets of ratios.

http://www.isuzuperformance.com/isupage ... impjr.html

1983-87 Impulse Non-turbo
First
3.785
Second
2.165
Third
1.413
Fourth
1.000
Fifth
0.787

and
1985-89 Impulse Turbo, Including 1987 Impulse RS
and 1988-89 Impulse Non-turbo

First
3.431
Second
1.963
Third
1.364
Fourth
1.000
Fifth
0.775

The first set look like Pontiac T1000/Chevy Chevette specs
the second set looks more "sporting", similar to the T9 from the Murkur

Gary

[mac5777]

Hi, I just spoke with John Esposito at Quantum Mechanics 1-203-459-9612. He said he has done two elans so far with no problems. And will have 5 speeds available in about 2 weeks. Call him for the details, he seems to have the tech answers.
A few years back he supplied a 5 speed for my spitfire that worked fine, and now has them for our lotus Elans.
Waiting for his price list which I will post. It has to be cheaper with a North American supplier for warrantees Etc. than dealing with the exchange rate and shipping from the UK.
The ring/pinion still sounds like it may be less $$. It is nice to have all of the option available.

Sarto

[garyeanderson]

I might have to arrange a road trip down to Connecticut too. Any way you look at it, either gearbox or R & P swap will cost more than all the savings on fuel for your ownership of the of the Elan. I bought a 97 F250 diesel and before I bought it figured it would take 150000 miles for the $3k to wash, fuel prices went from below regular to above premium. I have 199,000 and I think I may be even now. Both options will be because you want to do it, not because it makes economic sense. You may save some on water pump and valve jobs but really, lets be serious. Yes it may be a little quieter but not big noticeable improvement.

Gary

[mac5777]

gary,
You have it right, it's not to save money, one would just want to do it, It is strange, with a lotus, how just one little improvement can be justified regardless of any cost benefit ratio.

For me touring at speed at a quieter rev. and keeping the sporty feel through the gears is worth it. Maybe it's pride of knowing that it is now set up the way you wanted it. All though I keep coming up with new things. It's all for the joy of it, if you can afford it.

I was told once by a very wise friend that you will never get out what you put into a lotus restoration so you better be having fun.

Sarto

[264889socal]

I was faced with a choice of having new ring and pinions made for my Datsun race car. My supply of lower ratios had finally expired. After searching for a reasonable cost to replicate the three different ratios I used, I found one offs were extremely expensive. As an alternative, I chose to buy an Elite straight cut, dog ring transmission. It uses Hewland or equivelent Webster MK9 gears and drop gears for changing the overall drive ratio without buying large number of gear sets. For a street transmission, this is not a good choice.

As I mentioned while having a new input shaft machined, I was talking with the owner, he questioned why I didn't just have new ring and pinions made. I responded, I didn't believe I could resell that number of gear sets, as there is limited demand for this differential. Plus I would need to do this three times. It was his idea that we could have made ratios in batches of 10 and get the price in the range previously mentioned.

Now we were talking ring and pinions for racing purposes. Different heat treatment is required for street use. Long term use is not necessary for a race car and a stronger gear set can be obtained with a slightly softer treatment. Not many 100k mile race cars.

When I saw this thread, when I got home, I thought there might be an actual need for alternate ratios for the Elan. As I am just getting my car on the road, and last friday was the first day I was able to actually get the car out and do some driving. It was then I noticed the rpn/mph numbers. Higher than I would like for extended periods of time. To be honest, I couldn't remember the numbers on my original S7, equipped with close ration trans with a 3.9 and 5.20-13's as delivered, but they must have been similar.

While I live in a less populated area, and have acess to lots of great sports car roads, to take advantage of even better roads requires freeway travel upwards of 120 miles. And when traffic permits, freway traffic travels at 85+ in my neck of the woods. Not a happy combination.

It sounds like there is a need for alternate ratios. The numbers Wayne quoted me were for lots of 10. He was quite sure the upper number was attainable and possibly could gravitate towards the lower. Judging from these posts, it would seem a lot of 15 or more might be possible. The higher the number the lower the price. I trust his judgement in these matters as he has been in the business for over 40 years. Currently he does custom machining for just about any vintage street or race cars and was currently machining a batch of dog rings for Ferrari transmissions.

I will be picking up the input shaft in the next couple of days, as it went to heat treating today. I will ask him just what is needed to start the process and try to get a firm quote for actual costs. Will post the good or bad news when I get it.

Rob

[garyeanderson]

There is a informative spread sheet on the Westfield-world.com

http://westfield-world.com/gearboxshifts.html

put in tire size, diff ratio of your choice, Gear ratios
and it will give speeds in gears starting at 1000rpm and incrementing by 1000 to 8000rpm.

Put in your favorite 5 speed ratios and compare with the proposed 3.22 rear axle ratio or whatever ratio you think would work for your Elan. The intreresting numbers are first gear at 1000rpm, highway speed that you want to travel at, and top speed at your red line.

stock 4 speed gear ratios are
Ulta Close 2.51 1.64 1.23 1
Close ----- 2.97 2.01 1.40 1

Stock rear axle ratios
3.9
3.77
3.55
other available Ford and aftermarket ratios
4.11
4.44
4.7
5.1
Gary

[scott]

My elan has a 5 speed installed by Vegantune in the late 70's. Its a ZF box that was installed in early Escort Rally cars as well as a number of other vehicles. Works great in a hot elan but parts are a little hard to find. Military surplus in Austria is a possibility for parts, however. Just bought a spare from a Maserati Biturbo for less than $200. Designation is ZF s5 18/3. Scott

[msd1107]

The question was posed as to what differential ratio could be used to lower the cruising revs.

A previous post (http://www.lotuselan.net/forums/viewtopic.php?t=13892) approached the question from a slightly different aspect but the results can be used here.

Summarizing, depending on horse power, max revs, and tire size, the needed differential ratio varied from 2.89 to 3.37. Depending on your car, you may want something different.

The differentials have had pinion gears with 7, 9, 10, and 11 teeth and ring gears with 31, 32, 34, 37, 39, 41, and 43 teeth.

So you can get 2.82, 2.91, 3.09, 3.10, 3.20, 3.36 3.40, 3.44 out of these combination, although it is not cartain that all combinations can work. And you have the problem of acquiring each part individually and mating them. So it is probably better to go with a vendor who will make the set for you.

The other aspect of these high rear end ratios is what it does to the speeds in 1st gear. In broad brush terms, they are probably higher than what the average person would like.

An interesting question is, if there is a source who will make custom differential ratios, can they make custom ratios to fit in a T9 box? That would be the way to go for us US types.

David
1968 36/7988

[msd1107]

Darren,

Some additional possibilities for 5-speed conversions are:

Quaife USA has a T9 with a semi-helical synchromesh. The good point is that it is a bolt on proposition, coming with a TC compatible input shaft. The bad point is that it has the remote rear mount gear change.

This is manufactured by SP Components in the UK. I couldn't get a positive response from them about getting a proper gear change.

BGH Geartech has a variety of gear sets available for the T9, a couple quite suitable for the Elan. But they use the Sierra spline and the remote gear change. They claim you can use a Sierra clutch and it will bolt to the TC. They also claim to somehow solve the gear shift problem, but were not forth coming as to how.

Conversion Components (http://www.conversioncomp.co.nz/) has a web page with a conversion for the Elan. Colin Dray recommends instead the T50 transmission, a much lighter unit (27kg). He claims to be able to source better ratio sets, but I need to follow up with him. According to the web site, the gear lever is 390 mm from the front of the transmission.

Hope this helps

David
1968 36/7988

[worzel]

Hi All

Having just trawled thru the myriad comments on this subject I thought I'd add my own based on my own experiences of the Type 9.

In no order-

Complexity- depends what you mean. One comment I noted referred to the difficulties of this conversion. I can only speak personally but I converted mine (sprint) 8 years ago. Starting on Saturday with engine/box removal of the 4 speed unit, by Monday evening the engine and type 9 were installed. No real problems- it's a straightforward swapover. The only "oddities" (if that's the word) are the need to have a new gearbox support bracket made AFTER everything else is re-fitted. I didn't do this which meant the exhaust centre pipe had to come off again.

Cost- again depends. The box in my car was modified by the individual who first designed this conversion some 20 plus years ago (I keep repeating this point about how old this conversion is but there are still some disbelievers). The lever in mine is exactly where the 4 speed is and my conversion actually uses the simplest approach- but- it might not suit everybody.

Here's why- firstly the conversion on mine removes the reversing light switch mechanism (although it can be easily retained if so desired). Secondly- my gearbox does not have any spring loading against 5th. This is not a big problem- it doesn't affect the change quality in any way and in any case it's quite easy to fit a spring loading system as a retro fit WITHOUT having to dismantle the entire box by modifying the original Ford mechanism.

TWO other types of conversion can be done (this guy has done all of them)- but each gets more complex and involves more precision machining. None is superior to the other in terms of gear change quality/reliability so it's a case of diminishing returns kicking in.

Gearing- my box is from a 2.8 Capri so the intermediates are higher than those boxes from 1.6/2.0 litre cars. 1st is higher too (3.36) as opposed to 3.65 for the smaller engined sourced boxes. You could always uprate either box to 2.97 1st if you wanted.

2.8 boxes can be modified in other ways too- 5th as std is 0.825 as opposed to 0.82 on "smaller" boxes. It's possible on the "larger" boxes to uprate 5th to give 0.75 in top. Some figures- my car uses 80 profile 155/13 tyres with a 3.5 diff. This gives me 22.7 mph/1000 revs. The modified 5th would give me 24.9 mph/1000 revs. Would it pull this ratio?- all I'll say is that occasionally I'm looking for 6th!

There appears to be a lot of mythology about these conversions- at the risk of repeating myself- the AV conversion is by all accounts a good one- but I'm afraid this guy beat them by about 20 years! You could reasonably ask if his idea is so good why aren't more cars fitted with it.

Fair enough- basically because he's never bothered spreading the word- I only found out about him by pure chance and his argument for not getting involved in marketing the conversion is based on his own personal experiences, namely- many people like the idea but confine this interest to the level of "dreaming" (his words not mine). I can understand this since I've spoken to many would-be "converters" whose level of interest has nosedived once I pointed out that work and dirt are involved!

Cost- if you are reasonably competent mechanically (many elan owners are I know) you could do it yourself. The simplest conversion as per my car's cost me roughly ?400 8/9 years ago plus a clutch disc (?68), prop (?110), gearbox bracket (?15), speedo cable (hybridised from a sierra and elan item (about ?5) plus other odd small bits (about ?30). The whole lot came to about ?650 or so.

If you really want to go overboard and do the more complex version the cost for the actual gearbox machining etc might rise by about ?100-150 BUT the work is more involved.

Type 9 offers some advantages- you don't need a sandwich plate, the starter remains where it is as does the clutch slave cylinder and from underneath the conversion looks original (apart from the bellhousing being grey if you use the alloy one).

Hope you find my comments interesting.

John

[scott]

How do these ratios sound 3.42/1.94/1.39/1.0/.87 ....3.67(r). Scott

[msd1107]

Scott,

Here is what the GearList spreadsheet has to say. This assumes 155/80-13 tires, 7000 rpm, and 3.77 diff.

Ratio..%diff....Speed...Diff
3.42.................035.7
.........76.3%...............27.2
1.94.................063.0
.........39.6%...............24.9
1.39.................087.9
.........39.0%...............34.3
1.00.................122.2
.........14.9%...............18.3
0.87..................140.4
Figure of Merit -681.5 (max of 100)

The 1st to 2nd drop is 76.3%, much greater than desirable (which in the extreme should be less than 60% and hopefully closer to 50%). The 4th to 5th drop is 14.9%, probably too narrow. The speed differences between gears of 27.2, 24.9, 34.3, and 18.3 vary all over the place. They should be relatively the same or gently increasing or decreasing.

As a point of reference, both of the usual Lotus 4-speeds (the 2.51 close ratio and 2.97 wide ratio) have 1st to 2nd drops of close to 50%. And they both have Figures of Merit in the 90s. (The Figure of Merit is a mathematical measure of how well staged the gearbox ratios are)

I would be pleased to send you a copy of the spreadsheet so you can do more evaluation.

Hope this helps.

David
1968 36/7988