Quick Question about flywheels/backplates.

[mr dann]

Got myself a nice alloy flywheel and ALLOY backplate, snag is the backplate has been helicoiled, which I don't trust, rather than run the risk of having the backplate unship itself with fun consequences, I was wondering about bolting it from the back. ie:- having the heads of the bolts towards the engine and the nuts at the diaphragm end. This would be a lot more safe, since I am using a double grey diaphragm as well. I just can't remember what the clearance is with the clutch fully depressed. I need about 5mm I reckon. Might have to risk the helicoils or get the casing machined, any ideas?

[guru_1071]

the bolts will hit the bolts holding the endcase to the block/box.

id trust the helicoils, with a smidge of locktight

after all, how would you get a spanner on to assemble/disassemble the clutch assembly, it would be very awkward trying to do it through the starter hole.........

[love machine]

Ok, will do.

Stu

[cone]

id have thought the heli-coil would be stronger than the original alloy nowt to worry about IMHO.

[cooperman]

On aircraft engines you helicoils are mandatory as ordinary threads are considered too weak and laible to fatigue - especially in light alloy components.

[danwebster]

What motor are you running to need a double grey? Just out of interest?

[mr dann]

The 1380 which is about to have its pump put back on. 270 cam and geared to maximum 12 PSI residual, with intercooler. From a similar spec, they were looking at 165lb/ft which is more than enough. Superchargers put a lot of torque through at low revs. New drop gears in the post!

I do like the idea of a N/A race engine but they are too expensive to get a reliable one. Blowing is cheating but it's very effective. I'm going to sadly be pushed into the 2L class if I choose to compete in it.....

The brief being that I wanted it to accellerate like a hillclimb car and have a top speed of over 70! Hence high gearing and LOTS of welly, again, due to this the engine sees a very big resistance and needs the munter of all clutches to keep the plate from slipping!

It's going to be a nightmare in traffic!

[selbymsport]

cooperman said:

On aircraft engines you helicoils are mandatory as ordinary threads are considered too weak and laible to fatigue - especially in light alloy components.

Cooperman is on the mark, helicoil inserts in aluminium alloys preferred to direct contact we fit helicoils as standard practice in aluminium casings not as a repair but to prevent thread damage due to constant removal/assembly of casings on race engines

[danwebster]

Sounds great