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The gearbox - what breaks? - Engine & Ancilliaries/Gearbox - The Lotus Forums Jump to content
JayEmm

The gearbox - what breaks?

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Okay, I'm curious. I keep seeing people talking about upgraded Evoras/Exiges etc....

It appears to be a well known fact that the engine is extremely reliable and durable (to a point), but the weak point for anyone upgrading their car is the gearbox. JMG said so in an interview he did talking about the 430.

I am curious, what is it in the gearbox that is going to break? I believe a few years ago a company upgraded Esprit gearboxes to take the V8's power better, not sure they are still around though. Is something similar possible with an Evora?

I know the 400 has a meatier clutch than the S (as does the Exige 430), so that's one point of failure - but what inside the box breaks? I know Lotus replace gears 3-6 with their own, is it the gears themselves that break or something else? I'm not an expert in these matters I am just very curious. I suspect there are plenty of these boxes at breakers yards from the Toyotas they were originally used in.

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You'll be surprised how expensive gearboxes are from breakers.

As many on here know, my GTE gearbox exploded after only a couple of thousand miles of relatively gentle use. Following replacement, I don't know if Lotus ever collected it from Silverstone for analysis, but my guess is that Lotus re-assembled it incorrectly after they installed their ratios and that eventually something worked loose and was shot through the casing under load.

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Search is your friend. ;)

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Those articles I have read previously but neither seemed to provide definitive answers.

I have personally always felt like the 400 is torque limited in 1st and 2nd. Perhaps it is just the car's natural grip but it does NOT feel as rabid as I think it should. They pull harder in 3rd than 2nd I think. But maybe it's a placebo effect of some sort.

I know those are the two gears Lotus leave alone. Re-reading those threads it is implied Lotus updated/improved the gears they use at some point.... but clearly they don't have masses of faith in it themselves or am I reasonably sure we'd be seeing lots more than the power numbers we do out of the 430?

Yes I appreciate Lotus have emissions and warranty concerns to think of, which will always hamper an OEM vs a tuner, but it does seem odd especially when they're happy to give the auto box a little more torque than the manual (and I always though the auto was supposed to be the weaker of the two)

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The 4th-5th gear issue seems to be limited to the earlier Sport ratio boxes, and looks like it was fixed with a part spec change around the time the short ratio was made standard... IIRC?

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I think the power output is limited by the engine internals as well, particularly con rods.

 

 

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Having a hard time understanding the power output complaints.......seems pretty fast to me.  

400 / 410 BHP is pretty damn good and really all you need on public roads.....anymore and your going to have to be careful with your license.

Watch at 3.20 on he takes it up the rev range in 4th and says it's fast! This guy has driven a lot of faster cars.

 

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Human condition to always want more.  Previous to my 400 I had a GT-R that I had uprated to 600bhp with immense torque.  Still wanted more!

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It's not so much that I want more, but I was always confused how my Evora 400 *felt* less rapid in 1st and 2nd than my E46 M3, which had a good chunk less power, torque and more weight.

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I know of at least 2 „killed“ gearboxes in EX460 cars ... typical issue is thar you wont be able to engage certain geaers anymore  ... in the case I know I think it was 3rd gear... 

no clue what has broken inside the gb ....

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How much is a new gear box anyone know? (Fitted)

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I'd be interested to know more about the 6 speed manual gear box that Lotus use on the V6 cars (Aisin BG6) . When they fail, whats the common cause & are there known 'fixes' ?

According to Aisin's web site, its rated to 400 NM, which Lotus have exceeded (by 10%) in the latest V6 iterations.

With Lotus Cars re-building the 'box in the UK (closer ratios / LSD / adding an oil cooler), I would have thought its doubtful they still get it covered by the Japanese OE supplier warranty. 

410 - 440 NM seems low for a modern 3.5 litre V6, with a charge cooled TVS SC, suggesting Lotus hold the potential back. It's only a touch more than the original Evora S achieved, with a smaller, non CC SC  8 years ago.   The track only version of the 3-Eleven had a higher torque peak, but didn't use the BG6.  

The BG6 is classed as Aisin's 'High Torque' 6 speed transverse transmission but is intended for FWD use. Not many FWD cars exceed 400 NM, so thats fair. Does a added traction of mid engined location shorten the gearboxes life ? Certainly I know of a few failed BG6's that were fitted to stock Lotus Evora / Exiges. 

 

Edited by Cain-it

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