Message text written by "Zahid Ahsanullah"
>My recent gearbox rebuild on the 1980 Spitfire is not looking good.
>The car is on jackstands and in neutral when I start the car the
driveshaft
>rotates. It stops when I press the clutch as it should and goes into all
>gears except 1st. In first gear the shifter feels that it is engaged but
it
>grinds like the gears are just touching. When I put it in it looked fine.
It is typical for the drive shaft to turn when no gear is selected if there
is no resistance from the rear axle. As long as the clutch is engaged the
the layshaft gears are turning the gears on the mainshaft and although the
dog clutches are not engaged the drag from the bronze bushings will turn
the main shaft. I don't know why 1st is not working right. The fact that
2nd works OK tells me the shift rod is not stuck or disengaged from the
shift hub but perhaps something is preventing it from moving far enough to
properly engage the gear. Does the shift lever move as far forward as it
does when selecting third? Does it move as far back when selecting 2nd as
it does when selecting 4th?
>I also never got any answer for why a previously good Borg and Beck clutch
>with 500 miles now slips terribly. With the clutch engaged and brakes
>pressed, the clutch should not slip before 130 lbft of torque on the front
>harmonic balancer bolt. It slips at 70 lbft. No spring are broken and
>nothing is warped, whats going on here? The engine had gone to the machine
>shop for a partial rebuild but I am assured that the flywheel was not
>resurfaced. The engine rebuild is perfect.
One possibility is the clutch disk is installed wrong way round. If you
look at the disk from the side you will see the friction surfaces are
offset from the center section. If the disck is installed backwards the
center section will contact the flywheel and you will not get the contact
between the flywheel surface and the friction surface reducing the torque
holding ability of the clutch.
Another possibility is a fault with the hydraulics not releasing the clutch
completely. Try opening the slave cylinder bleeder valve to see if there
is any residual pressure.
Good luck
Dave Massey
IEEE Member #6968069
Past chair, St. Louis Section
57 TR3
71 TR6
80 TR8
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