C64 box killers - post in here

Topics relating to the Lotus Exige S2 (series 2)
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andybond
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I am trying to make up a little bit of a store of data for all of you who have sadly killed their c64 box

Could you be so kind as to detail

Year of car
Power of car
Original box?
Box fluid changed before failure ( time ? Day / week / month before ? )
LSD? Factory or aftermarket?
Speed when failed ( approx )

Thanks!
ade
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Being one of the earliest to kill the gearbox

Year of car 2006
Power of car 300hp 200lb/ft
Original box? Yes
Box fluid changed before failure ( time ? Day / week / month before ? ) Nope completely original
LSD? Factory or aftermarket? No
Speed when failed ( approx ) 6,000rpm ish in 3rd
Failed 2009

It is on youtube......



After that it got,
New gearbox (I drove it home from Spa 350 miles with no 3rd gear and the old box was completely destroyed inside)
Quaiffe LSD
Jubu semi helical 3rd and 4th
JDS laminova gearbox oil cooler
Redline MT90 oil
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andybond
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R1Brizz from Seloc

2008, Komotec 320S, factory fitted box, Redline Oil every 2 years, No LSD, entry to corner changing down into 3rd at around 40mph - instant grinding and box locked.
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andybond
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WillB from Seloc

2006 Exige S 220
Approx 58,000m, majority road use, no heavy track use.
Original box, failed at low road speed. No diff
Diff broke in the gearbox, so no drive at all.
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andybond
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535Dboy from Seloc

2008 S - tuned to 280Bhp
c30k miles
3rd gear went pop at slow speed. Managed to get it home as about 2 miles away !
Open diff

Heavy track use and had just come back from Spa having been driven hard by an ex F1 drivers son around there which was fast and I forgot to put the Go-pro on!
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evo_ufo
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What’s your goal here Andy.? We all know that there have been issues with the gearbox particularly on heavily tracked or modified cars. I find that these type of threads can be bad for the brand if it makes it seem like there is a bigger issue. You aren’t going to get people jumping on to balance the thread and explain how rare the issue is on stock cars.

Advice to anyone with a concern would be to upgrade 3rd 4th and final drive. Decision is just whether to do this proactively or whether to be optimistic and keep fingers crossed and then upgrade if and when it goes.
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andybond
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My goal is to understand what kills the box.

4 out of 4 so far had no diff. Is that a pattern?

It’s not track use that kills them exclusively , and it certainly doesn’t appear to be power related as 2 were standard cars.

I don’t think it’s bad for the brand if we understand it. There are pockets of information but no one appears to have taken the time to correlate results.

Just trying to understand patterns.
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evo_ufo
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Box was designed for 190 hp in Celica. Little wonder there are some (not many) failures when pushed beyond that in Lotus application. Led to believe that’s why the series production cars didn’t go above 260hp.

For the record I pulled 5 teeth out of std final drive on mine with Quaife LSD. That was with around 300hp and 220 lbft. Bad luck (Or served me right) as only 2nd track day after removing a straight cut final drive as it was too noisy. Now running semi-helical. And also now running gearbox oil cooler.

As far as I’m concerned it was torque and track use that killed it, hence the upgrades to cover as many bases as possible.
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andybond
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I understand where you are coming from. I am just trying to work out if there is a pattern, I wholeheartedly agree that a box that was designed for a whole 133ibft and then asked to do 32% increase is stretching it a bit!
ade
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I'm with Will here, the main issue is the design of the box was for a car with no torque, my first torque related failure came on the dyno as we hit 260hp and it literally spun out the clutch just on power as there wasn't enough clamping force.
The design of the box allows for slight de-meshing of 3rd and 4th at the box gets hot and is under load, also the gears are skinny for 3rd and 4th. Add it getting very hot on track extra torque and it will break! Add in shock loading on track over curbing and that just makes it more likely to break. Therefore;
put in stronger 3rd and 4th, consider the final drive as well
add in a cooler, using a laser temp gauge the casing was over the operating temp of the oil, that means the oil probably was as well, I'm not sure but I think running my cooler took out 30 or 40 degrees of temperature from the gearbox case
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