Lou wrote,
>Here is a question for people who race cars.
>
>I had intended on using the early style flywheel (an original stage II
>Sunbeam part) and the 9 spring clutch because they have the widest grip 8
>1/2" and tightest grip of the Sunbeam products. I then held a 9 spring
>clutch in one hand, and the Series 5 clutch (7 1/2") in the other and there
>has got to be 5 pounds difference, at least! I can see why many racers are
>using the series 5 style clutch now, but is the trade off in slip better
>than the trade off in acceleration? Has anyone sat down and figured out
>which clutch/flywheel system is better? I do know the Holbay guys marketed
>the early style clutch/ flywheel system. Someone there thought it was a
good
>idea. Any thoughts? Lou
I have run both the early and late clutch in my car.
The early clutch was great, no slippage whatsoever.
When I put in the 1725 (to replace the 1592) I bought a new 7 1/2"
cover and disc.
The stock engine didnt seem to overpower the clutch, but after adding
fuel injection, and later side draft mikunis, the clutch couldnt cope.
Adding a hotter cam to the equation made the clutch slip at wide open
throttle at any RPM above 3000.
The engine now makes probably 15 or 20 lb ft of additional torque, but
the clutch doesnt seem to have the clamping power.
Some people have done things like putting two diaphragms on the later
clutch, which doubles its load (also doubles pedal pressure).
I had a racing clutch built up by Kennedy Racing Clutches.
They took off the shelf goodies together, and made up a 7 inch clutch,
that is quite a bit smaller and lighter than a stock 7.5 inch unit.
The cover even has a thrust plate on it so that the stock TO bearing
can be used.
The clutch is like a tilton multi-disc setup, but with only one disc.
This clutch also features repaceable tension shims, and a sintred iron
friction disc.
They also modified an early flywheel, and lightened it down to what could
be done. The area where they left the flywheel mass was such that the
mass was minimised on the outside, which reduces the moment of intertia.
I think it came out that clutch and flywheel ran at 19 lbs total.
Its not in the car yet, but should easily cope with the amount of torque
that the engine will make.
Jarrid Gross
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