Evora IPS/auto going clunk at low speed

[chylld]

My Evora 400 auto has developed a worrying "clunk" sound that is not only clearly audible, but can also be felt through the chassis. It happens when slowing the car down to a stop; it typically happens at around 5kph or so. The deceleration can be completely smooth but the clunk will happen regardless.

It also makes the same noise if you reverse a few metres, and then start driving forward - it'll go clunk almost straight away.

I had the dealer check the car out, they took all the wheels and brakes off and spent 3 hours checking every single bolt holding the engine and suspension together, and couldn't find the cause of the noise. They even had one guy jump into the boot to visually inspect the engine bay while the clunk sound happened, but nothing could be seen to move.

Factors we've been able to dismiss:

• Fuel - happens with full or near empty tank
• Harness bar - thought the SSC harness bar might have been torsioning the chassis in a bad way, but happens with/without it
• Seats - double-checked that all bolts are tight and there is no freeplay
• Nothing physically loose, e.g. battery
• All brake pads checked for play, fresh copper grease applied, still happens
• Brake discs dismounted, cleaned, remounted, no effect
• Not specific to a particular gear, it clunks whether I decelerate in 1st or 2nd

The only things left that I can think of are:

• Handbrake, I'll see if it happens with some light pressure on the handbrake
• Torque converter locking action, which correllates to the speed at which the clunk happens

The car has 7800km and 8 trackdays under its belt. If anyone has any ideas, they would be immensely appreciated.

[21gg]

The odd time I've had a clunk if my car was stone cold and I select d/r. However it's only done it a handful of times. Also as I normally let the car warm for a couple of minutes normally it's as smooth as anything. I've always presumed it's just cold fluid in the torque converter. So I would guess at the torque converter locking, so possibly an oil issue? Software issue or a physical fault?

Gav 

[chylld]

Today I checked if tension on the handbrake affected the noise at all; it didn't. So as you suggest, torque converter is looking even more likely to be the culprit. No warning lights so I think it's purely a physical fault. I get the noise regardless of engine/transmission temperature.

[21gg]

I wonder if it could be the software, its as if its doing a full on quick change, as if you were hammering on in sport mode, rather than just gently setting off?

 

Gav

[chylld]

Good thinking, however unlikely as the clunk still happens if I hold the car in 1st gear at 20-30kph and then slow down to 0 (so no gearchange).

[21gg]

Mmm maybe not then.

[Likuid]

Mine seems to be rough sometimes at low speed in 1st, but only if in Sport/Race. If its in normal its super smooth. Is it happening in all modes?

[chylld]

10 hours ago, Likuid said:

Mine seems to be rough sometimes at low speed in 1st, but only if in Sport/Race. If its in normal its super smooth. Is it happening in all modes?

Yes happening in all modes.

Some further research into the U660E auto box reveals that some Toyota owners have similar sounds in their cars. In their cases it's either the ABS doing a self-test (only once per engine start-up though) or an indication that the transmission oil needs to be changed.

Booking my car in for a gearbox oil change as the service notes suggest I do so about now anyway. Normally required every 58,000km / 4 years, unless the car is tracked "occasionally" in which case it needs to be changed every 7,500km / 6 months. (My car has done 8 trackdays and 7,800km)

[French Frie]

@chylld : I've read that a common fault on U660E is one or several faulty solenoids (they are 7 on it), but the most likely is wrong/used oil ... I changed mine for full synthetic Motul ATV VI, which is OEM WS oil compatible, but with higher specs. I can't say I noticed the difference, but gear change was fine before, and it is good for my peace of mind  ! almost no track use for me, but I wanted to anticipate the fluid renewal ... and there was a recall on oil cooler/thermostat/oil lines on my car anyway, so it was mandatory anyway !

hope you'll fix it easily ...

Edited October 19, 2017 by French Frie

[chylld]

Thanks so much for the info  Really hoping an oil change fixes it.

[French Frie]

you're welcome   ! here's the document I read about U660E solenoids issue  : http://www.gearsmagazine.com/resources/issues/6f8d1_2013-1_all nbg.pdf

[chylld]

My dealer called today to say they can't change the transmission oil until a month from now... too busy setting up race cars for a few events until then. Hoping the gearbox holds together, I have a trackday in 2 weeks and the clunk has developed into the occasional double-clunk

[21gg]

Surely once the underway is off anyone can change the gearbox oil. It us a Toyota box afterall!

I wouldn't want to be doing a track day while you've got issues with it.

Gav 

[French Frie]

U660E has a specific procedure to change the oil ... you have to fill it  and top it up at a precise temperature, otherwise there would be too much or not enough oil in it ! there is a kind of tube attached to the oil bolt, and oil has to be level to the top of this tube when this temp is reached... So oil temp has to be monitored by Toyota (or lotus) diagnostic tool. few tutorials on Youtube, but not specifically for Lotus ...

But indeed, a well informed dealer can do it !

[chylld]

Cancelled my trackday. Driving home from work I tried to upshift during a long sweeping corner at moderate Gs... box couldn't find the next gear until after the corner. Previously that had only happened occasionally on track. (upshifted well before redline, so not a rev limiter issue)

Also just heard from another friend with an auto Evora 400 - he has the same clunk now too.

[21gg]

That sounds similar to a trans oil change on a boxster that I watched on wheeler dealers ?! Why they make things so complicated.

Strange that this is surfacing with the 400,  not heard any reports with the S1......famous last words!

Hope it's something simple to sort, a pain about the dealer though.

Gav 

[French Frie]

Jonathan, I hope it will be sorted by an oil change, but it would be interesting to have a full report from the Lotus tool, as it would tell you how far the gearbox temp has gone...

[mcx]

Sorry to hear your transmission woes... my manual Evora 400 developed a very similar noise... it reminded me of my ‘60s midget that had worn splines on its hubs.. sometimes on accelerating and also on decelerating when the speed had dropped right down. It was a while back and I px’d the car for the exige so never got to the bottom of the issue. Very odd that manual and autos have a similar clunk, maybe coincidental. I checked all the wheel bolts/ hubs etc and found nothing. Hope you get it sorted out

[chylld]

Thanks guys, look forward to getting it sorted out. Very strange to hear that the manual is also prone to such a noise as all my symptoms point to the auto box. This morning driving to work it even hesitated on upshifts in a straight line  or perhaps I'm paying more attention to these little hiccups than I normally would.

Have another big rattle coming from the back of the car somewhere on bumpy roads. Sounds kinda similar but is just a sound, as opposed to the main clunk which can also be felt through the seats.

[French Frie]

any update, @chylld ?

 

[geartox]

On 26/10/2017 at 08:01, French Frie said:

But indeed, a well informed dealer can do it !

which dealer for your car ?

[chylld]

6 hours ago, French Frie said:

any update, @chylld ?

 

Car is booked in for service next Wednesday. Downside of the dealer being a race team is that they have to prioritise those preparing for competition first. A flurry of events this month meant that I had to be pushed back several weeks. (Missing one of my own trackdays in the process but it wasn't a competition event anyway)

Also kinda hoping that fresh transmission oil helps with my fuel consumption... the car is only getting about 150 miles before the fuel light comes on. (Driven on the street very sedately)

[chylld]

Just dropped my car off for service. Not without drama though; on the way there, in a congested tunnel, the car stalled. (It's an automatic.)

Have been noticing a few coughs/splutters every now and then (regardless of engine temperature or fuel level) but this is the first time it's totally stalled. I was decelerating in D(rive) at about 20mph/30kph when the engine cut out. Engine light, battery light and oil light came on, and the gearbox went into N by itself. Was able to restart the engine with the starter button while rolling. Dealer ran diagnostics asap, but nothing came up.

The last week or so the car has really been struggling to start... it barely ticks over and then runs really lumpy for about 10 seconds at 500rpm before smoothing out. I've had this before with a bad battery, but I'm currently on a relatively new one. Dealer is going to check the spark plugs, but I suspect it's a fuelling issue.

Fingers crossed the car is all well and better when I pick it up this afternoon....

Edited November 21, 2017 by chylld

[Bibs]

How old is your battery? 

[chylld]

12 minutes ago, Bibs said:

How old is your battery? 

1 year 2 months, Supercharge Gold MF66. Was put in 6 weeks after I took delivery of the car (factory Varta already started having issues.)