Lotus Elan

3.55 gears

PostPost by: gus » Thu Jul 28, 2016 10:51 am

The +2 weighs 400 pounds more than the Elan, and was never a thrilling performer from the get go, but it is supposed to be a performance vehicle. When you put in a final drive that can make it difficult to get under way on a hill, I think you have done a disservice to the car.

most of the time, on the highway it is hot as all get out and you have to have the windows open anyway, not very quiet

A simpler and cheaper solution is to buy a louder radio.
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PostPost by: Quart Meg Miles » Thu Jul 28, 2016 3:17 pm

I don't recall my S130/5 being slow to get going, but the clutch was incredibly heavy and should be considered as a factor if the 5-speed route is taken which, otherwise, is a pretty good compromise.

Ironically, the brakes were over-servoed, yet in another thread someone thinks they are too heavy (so he must have a 4-speed)!
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PostPost by: Orsom Weels » Thu Jul 28, 2016 4:58 pm

Some info you may find useful/interesting. I wanted to know what the actual rpm difference would be & if it would be worthwhile changing my 3.77:1 to a 3.54:1 diff on my +2. What made me wonder is that I don't notice much difference between my Elan with a 3.55 : 1 diff, fitted with std 155 x 13 tyres, & my +2 that has a 3.77 : 1 diff & 165 x 13 tyres. These were calculated using an average rolling radius of at least four different tyre manufacturers offerings & based on new tyres, ie full tread. As you will see in the table attached, there is only just over 100rpm difference at 60mph between my two cars & it would make less than 200rpm difference if I were to change to a 3.54 : 1 diff in the +2. For me, not worth the effort & expense.

Edit, I just thought I should mention this is all assuming a 1:1 4th gear
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PostPost by: Sea Ranch » Thu Jul 28, 2016 8:39 pm

Tires are definitely a simpler way to help out the over-all gearing. Pay close attention to the diameter & circumference specs before you buy. :mrgreen:

Unfortunately, the tallest tires are sometimes the most expensive (like the Vredestein Sprint Plus). :(

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PostPost by: stugilmour » Thu Jul 28, 2016 11:37 pm

My Plus 2 has a Ford MT75 five speed (0.82 overdrive) and a 3.55 diff. Also run stock size Vredestein tires (80 or 82 profile) from Coker Tire. Love the combination. About 3500 rpm at 80 mph on the Superslab. Fifth is strictly for cruising. Really like the tires way better than the commonly available lower profile rubber, and as mentioned you pick up a few hundred rpm at cruise. Highly recommended as a first step before the diff change.

I can't recall the MT75 first gear ratio off hand, but believe it is a bit lower than the Lotus four speed; if anything it could be a bit taller. When ever we have discussed the topic before the rather low first in the MT75 is often mentioned. The Spyder supplied MT75 clutch setup is very good, with an axial type slave cylinder and very light take up.

One thing I found makes a big difference for getting away in first is ditching the Rotoflex for CV's. Heck, you have the diff out anyway right? :D

The extra Plus 2 weight was really probably at the edge for the Rotoflex design.

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PostPost by: Lotus 50 » Fri Jul 29, 2016 12:58 am

A comparison

Plus 2 first = 2.97, diff = 3.77, tires = 185/70-13 (my car anyway)
My 1991 Miata first = 3.136, diff = 4.3, tires = 185/70-13

The Plus 2 is geared pretty tall in first gear, even with the 3.77 gears.
R&T's 1972 test shows 3200 rpm at 60 mph. My tach reads higher than that. Maybe I should get my tach calibrated. Of course if I drove faster it would be even louder.
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PostPost by: Harvey » Fri Jul 29, 2016 2:37 am

I have run the original four speed box with the 3.77 diff for 18 years and have put in 500-600 mile days on US interstates running at 75-80 mph and have never thought I wanted a more relaxed gear for this type of work. I love the responsiveness of the car with this setup. I am running 185/70x13 tires at the moment but, like Stu, I am going back to the original 165/80 series on my next tire change. I think this will add an even more delicate feel to the car.

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PostPost by: Sea Ranch » Fri Jul 29, 2016 4:02 am

So nice to hear this range of experiences. It really is somewhat subjective, and also a little bit of "what you're used to".
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PostPost by: david.g.chapman » Fri Jul 29, 2016 12:12 pm

Here are some pictures of my exhaust setup.

You should see two views of my extra box in front of the original rear box, and also a view of my tail pipe (with altered brightness), so you can see the closed end of my baffle tube. The closed end was just made by squeezing the tube in a vice.

There is plenty of clearance under the new middle box - in fact the lowest point of the exhaust is the y piece clamps near the front, where the clearance is 5 inches unladen.

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imag0287.jpg and
Looking into the tailpipe
imag0289.jpg and
middle box 1
imag0288.jpg and
middle box 2
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PostPost by: prezoom » Fri Jul 29, 2016 2:14 pm

Just received a catalog, along with a new oil pressure gauge for the Zetec, from Merlin Motorsport. On page 74, they list decibel inserts. Hard to tell how effective they are, but they may be the answer for reducing sound.
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