915 trans HEAVY DUTY clutch supplier needed!

[911hillclimber]

My heavy duty Sach alum cover clutch kit for my 915 race box is falling apart I think.

I'm told by a very knowledgeable Porsche racer today there is a race version of this road going clutch.

Anyone know of a source please?

[jwhillracer]

Hi Graham, your best bet would be to replace it all with a Helix triple plate clutch or similar. You would have to replace the flywheel as well, but it’s a good fix, we have only reconditioned ours 3 times in 30 seasons competition (including the present rebuild) and spares and replacements are local and (reasonably!!) easily available.

JW

[Yellow491]

Hi Graham
How many bolt is your crank,i have a couple of brand new helix twin plates and flywheel,they are fairly bomb proof as JW says,& light.

[911hillclimber]

I'll know the bolt number soon when the box is off and I can look at the clutch. That should be end of thursday this week.
The engine is 1986, so is the crank.

I have looked on the net for a better clutch kit, but seems the choice stops at the sache HD unit, but that is the same as the one I have now.

This engine is 320 bhp at best, and about 243 lbft. The car is 560 Kg and of course the slicks, but that should all be ok i think with the HD cltch?

I'll wait please until the clutch is open, as I am only guessing the harsh vibration is the clutch.
At first i thought it was a broken engine mount, it is that bad.

Ran 3 x 33 secs in practice and timed runs were low 32 secs, so the engine i think is fine.
Gear change ok!

[911hillclimber]

Gear box off today.
The cover plate is eccentric, or rather the pressure plate of the cover is eccentric.

The Sashs clutch uses 3 sets of straps to centre the pressure plate to the alum housing that in turn bolts to the flywheel.

One of the straps has buckled due to one fastening riveted pin tilting and thus the alignment is lost and the plate has shifted across. The one side of the plate is touching the alum housing and diametrically opposite the plate is 3.47mm clearance. The clearance would normally be equal all round.
The support of the rivet in the alum housing is very weak, about 3mm when it could be 6mm, crap design!

So, the pressure plate is eccentric and no wonder the vibration was awful but the gears all worked.

The pressure plate is perfect, the thrust bearing perfect too, so I need another sachs heavy duty cover plate pronto and the car will be back in business.

Hope these pics interest:



The bad damaged strap:



And a good one:

[911hillclimber]

Had a good chat with Helix racing clutches this morning.
They make (literally in their factory(!) a racing cover plate which uses the Sachs driven plate and thrust bearing, albeit 2 x the price of the Sachs HD clutch.

They question if my dead cover plate is indeed heavy duty.
So, off to Banbury tomorrow to compare the 2 covers and if convinced, will hope the Helix is an upgrade to the Sachs.

It is a loss of £300 if you can't run at an event.
Got away with it this time, but next?....

[Nine One One]

You could always ask once there, if they could repair the one you have (if a heavy duty one) then at least you have a spare as well?

[911hillclimber]

Good idea as ever!

I think the hole for the distorted rivet of the bent strap is too distorted, but worth asking.

[911hillclimber]

Had a great trip to Helix Motorsport this morning close to Bicester.
Great place, people and stock! Hundreds of motor sport clutches and some real oddities too.
Real engineering.

Bought their uprated cover after a detailed chat about the application.

The cover plate is a direct replacement so I can use my organic sprung driven plate and release bearing.
The design detail is superb, bomb proof compared to the Sachs which was deems a road standard clutch, nothing heavy duty, so I was misled by the supplier...

Pictures below will be of interest to the techies here.

Will be going back into the car tomorrow and the engine run.
The cover can be refurbished when worn at less than new, made in England, fit for purpose (350 ftlb dynamic and high static torque rating) and £560.

Feeling very positive about this little adventure.

Helix on the left:



Helix on the right:

[Nine One One]

Claim against the original supplier of the so called Heavy Duty one you bought last year?

[911hillclimber]

Have sent them an email 2 days ago with pictures.
ZERO response.

In fairness they disclaim any warranty if used in track days or racing, but just 40 start line launches and less than 30 miles?
No response means they could not care less, got your money, off you go.

I won't return. Doubt they care less.
Might be surprised when i prompt/ remind them for a response.

[Nine One One]

Just mention Trading Standards, and they sold you a so called Heavy Duty item, which has been identified as a standard cover - irrespective of use, it was mis sold as something it clearly is not.

[911hillclimber]

I think they could not care less. Will not use them again!

The Helix clutch is back in the Lola and works a treat, super super smooth right through tick-over to red-line.
Pedal effort much the same as the old Sachs clutch yet has a torque rating of 360 ftlb.