Clutch slipping when cold

[A.Wang]

I was driving the S2 up to Birmingham (to see the boys at EMC) this morning, and within the first 20-odd miles the car suddenly felt like it got knocked into neutral without warning. I had my foot on the accelerator, so the first time it happened I rev'd to redline before I realised what happened. Dropping it down the gears had no effect - the clutch would bite for a split second and then immediately let go, with the rev counter shooting towards the red.

The odd thing was, once I pulled over to the hard shoulder and stopped the car, the clutch "came back" and it would behave perfectly for a while. This happened 3 times - all without warning - and then stopped for the remaining 100-odd miles of the journey. To say that I was very nervous was an understatement! I have used the car on my commute quite a few times before and that has never happened.

Has anyone experienced this before? It's all very weird - luckily the car's now with EMC, and we have a couple of theories - small oil leak onto the clutch plates is one possibility...another theory is that a previous owner had a 2.5L clutch fitted, which would've got chewed up by the S2 engine in no time.

 

[James_G]

It's a new one on me but I remember my dad suffering something similar and that was due to oil on the clutch plates. Having been up close and personal with a 944 S2 clutch this weekend it could be that you rear main seal is weeping oil slightly, which could easily contaminate the clutch.

Anyway, far more interesting is what mods you are having done at EMC? Full on track spec engine perhaps???[]

 

[A.Wang]

The "initial" stage of mods this time round includes a full welded-in roll cage with additional reinforcement on the transmission tunnel and slightly different door bars - it's a bit more horizontal at the A-pillar end (60 degrees rather than 90) compared to the ones they use in race cars, so I can get in and out without having to fold myself in half! I'm also getting some single adjustable Gaz shocks (EMC spec ones) for all corners and getting a brake upgrade (braided hoses, new discs and pads).

The interior is getting stripped out, to be replaced with a pair of Corbeau Sprint XLs, with suitable harnesses (I'll go with whatever EMC normally uses). The steering wheel has been replaced with an OMP Superquadro, although the boys will be fitting a better boss kit, possibly with spacers. The rear carpets are all going back in as this is going to be a road-legal track toy for now, and I intend to drive to and from track days in it (also, I don't have anything to tow it with).

I'm also getting a few annoying things checked out and fixed too - the excessive play in the gear lever, the randomly slipping clutch, the dirty ABS sensors and a horrible groaning noise when I steer the car at low (parking) speeds.

The engine is getting looked at, and the fuel-air mixture tuned on a rolling road at some point, but we won't be touching that as part of stage 1. Likewise the air filter and exhaust will both be left alone...for now. The boys threatened to turbo-charge it - that could be fun as a turbo 3-litre engine would be, erm, interesting (read: scary)!

 

[James_G]

Sounds fabulous. I look forward to seeing you at a track day soon as I have commited to days at Castle Coombe (May 8th) and Silverstone (June/July TBC) this year at the very least. I'll be interested to hear what you think of the EMC Gaz suspension options, as I believe it's less than fitting KW V3s, but more than Koni Sports.

 

[A.Wang]

The Gaz shocks are customised for EMC's race applications, specifically tailored for the 944 - they're not the same ones you'd buy off the shelf, so I am confident they'll be spot on! []

I'll let you know which track days I'll be doing this year - I plan to do the shake-down/set-up days at airfields by Motorsport Events, before taking the car on circuits. If you can find an open pitlane day at Silverstone I'll definitely be interested - I tend to avoid sessioned days.