Gearbox - a problem we haven't seen before

[TBD 781]

I've always had the fear of a potential gearbox or clutch failure at the back of my mind, which is why, for example I've never used the launch control or done hard starts. And, in fact, I've never had any actual gearbox issues with the car, it's always been near perfect.

Nonetheless, after a long drive beginning of August I woke to see a puddle of gearbox oil under the car - gearbox oil. Went off to my local garage where we opened the undertray to find this. Obviously the case has cracked and is leaking gearbox oil. Strange thing is, the case seems to have fatigued in an area without mechanical stress, the fins showing nothing, but the surfaces showing multiple fatigue cracks.

We concluded (together with Komotec) that the car was not fit to drive, so it has taken a bit to organize transport. The car finally got to Komotec yesterday and the issue is obviously a guarantee case, but it looks like EX460 be off the (french) roads a bit longer.

 

S

[C8RKH 6,436]

Ouch!

[chumaxa 97]

How can you actualy crack the gearbox like this ? Sorry for you.

Edited August 29, 2019 by chumaxa

[ramjet 1,090]

Interesting that all three cracks seem to line up in a sort of semicircle on the box itself.

I have never seen anything like that before.

I'd be going with a casting fault.

It would be interesting to find out whether the cracks coincide with a machining line or something like that on the inside.

[TBD 781]

10 hours ago, ramjet said:

Interesting that all three cracks seem to line up in a sort of semicircle on the box itself.

I have never seen anything like that before.

I'd be going with a casting fault.

It would be interesting to find out whether the cracks coincide with a machining line or something like that on the inside.

This is exactly what I'm thinking.

 

[ramjet 1,090]

Is that on the gearbox input shaft casting?

[TBD 781]

I finally picked up the car after 4(!) months, three of them waiting for Lotus to deliver the replacement bell housing.

Turned out the real culprit was a disintigrating differential, where the axle hat pulled. It was then probably the unballance that caused the housing to fail. Komotec spent a few hours cleaning the geabox from metal bits and pieces. It was such a rare fault that Lotus specifically asked that Komotec return the broken differential for analysis.

On the upside, I did get the Quaffe installed instead of the stock diff - heavily subsidised by Lotus.

 

[trcm 125]

Intriguing failure mode, glad you caught it before it did any more damage, even if it did take four months!