TRANSMISSION
 

GENERAL HYDRAULICS

    - If you increase the master cylinder bore this will push more fluid into the system for any given movement but will reduce the pressure - so the pedal pressure you have to apply is increased, but movement reduced.

    - if you reduce the master cylinder bore this will reduce the amount of fluid pushed into the system for any given movement but will increase the pressure, so the pedal pressure you have to apply is reduced, but movement increased.

    - if you reduce the size of the slave cylinder this will reduce the pressure and increase the movement. Thus less pedal movement but more pressure.

    - if you increase the size of the slave cylinder this will increase pressure and reduce the movement. Thus more pedal movement but less pressure.

    - remember if you get too much movement the inner ends of the diaphagm spring can foul the centre of the clutch plate.
 

CLUTCH RELEASE MECHANICS


When fitting modified or new clutch assemblies it is advisable to check the distance from the rear of the engine back plate to the face of the clutch release spring/fingers, then using this dimension set the release bearing the same dimension back from the front of the bellhousing. Now check.

1, is the bearing carrier running centrally about the drive shaft? If not does the pivot bolt need tightening/ does it have a nut on, often the ally thread is stripped in the casing. Maybe the fork needs bending up or down.

2, does the bearing need packing out, if the clutch arm swings too far forward it will run off center leading to premature wear on bearing and spring ends.

3, is the pushrod long enough to release the clutch? Is it too long? Often you will find the rod has already been modified by the previous owner, especially if it was fitted with a carbon bearing.

4, CHECK THE BUSH IN THE END OF THE CRANK, FOR WEAR OR EVEN IF IT STILL EXIST, IT'S EASY TO OVERLOOK BUT CAN END UP BEING COSTLY.
 

5 SPEED GEARBOXES

We all know about Ford and Toyota conversions where you cut the cross member. Well I guess you're never too old to learn something.  I've been messing with Sprites, Midget and A40's since the 70's and this week Laurent from France asked me a question about modifying a flywheel for his Datsun 5 speed box? I remember working on my Dad's Datsun Cherry and realising how similiar but better than the Mini's it was but didn't know they did an inline 5 speed also based on BL A-series.  It appears the rest of the world, where these were more popular knew this and came up with kits to fit the 5 speed without the need for cutting cross members or propshafts checkout rivergate5speed.com/ for more details.
 

 OMNI-AUTO'S SPRITE/MIDGET CLUTCH ROLLER BEARING MK I


First go to your local scrapyard and buy a MK II Cortina release bearing carrier.  Now find yourself either two pieces of 1/2" diameter bar x 26 mm long, or two old valve guides. I prefer the valve guide method as it doesn't rely soley on my welding for strength, although having said that the first one I made using bar is still running four years and three cars later. For bar assembly instuctions follow 1,2b,3,4,5 and for valve guide assembly follow 1,2a,3,4, and 5. (See diagram)

1) Grind the 2 rivet heads off and discard the back plate. Now remove the bearing (carefully if you intend using it again).

2a) Clamp an old valve guide in to the first scollop.  Drill through and repeat on the other side.  Tap one end of the valves and holes you have just drilled (5/16 unf).  Braze or loctite pieces of studing (or thread cut off the ends of some bolts) so it sticks out approximately 6mm.  If after fixing the stud sticks into the main orifice, file back to the carrier profile.  Screw on valve guides tightly and clamp down.

2b)  Clamp 1/2" mild steel bars to scollops in carrier.

3)   Mask the ends of the valve guide/bars with masking tape. Electric weld (arc or mig) all over between the valve guides/bars and carrier.

4)   Now using a piece of sheet steel or washer, cut up with a 1/4" radius in it as shown, place it on using the operating fork, not forgetting to allow for retaining clips, centralise the assembly and weld or blaze the pieces in position. Cut off excess valve guides/bars.

5)   Deburr, clean and paint the assembly, press on bearing, grease spigots lightly and fit to car in usual manner.
 


 

 OMNI-AUTO'S SPRITE/MIDGET CLUTCH ROLLER BEARING MK II

Using a standard Carbon Bearing Carrier, smash out the carbon (this is usually easier than you'll expect) Make an alloy Joint piece with stepped outside Dia's, one to be a push fit in the Carrier and one a push fit in the Bearing. The hole in the centre need to give you plenty of clearance on the drive spline. Check the distance you need to stick out as this will very (see notes on centering bearing above).


 

WHEN USING ANY ROLLER CLUTCH RELEASE BEARING ALWAYS REMOVE THE CAST CENTER FROM THE CLUTCH COVER AND ADD A SPRING TO PULL THE BEARING AGAINST THE CLUTCH COVER.

OMNI-AUTO`S MK I ROLLER CLUTCH RELEASE BEARING  - RA_RHD3259  Q_CCT79  A_HD3259
 


NATIONAL AUTO PARTS DO CLUTCH KITS WITH A ROLLER BEARING - NHD0117  AND THERE IS ALSO A COMPLETE KIT - NHK420 BUT ROLLER BEARING MUST BE STATED OR CARBON MAY BE SUPPLIED.
 


 REMOTE CLUTCH BLEED

This can be made using 1 piece of brake pipe with 2 male ends and 1 double female nut. Fit 1 male end into the bleed valve hole fit double female nut to the other end, and attach to eng/gearbox fit original bleed valve into the other end of double female bleed system. Remember to secure the pipe and bleed valve end to stop it whipping about. We braze a piece of steel, in the centre of the double female nut, with a slot cut in it to locate it behind an eng/gearbox bolt.



MODIFICATIONS FOR FITTING 1275 CLUTCH
ASSEMBLY TO 950cc FLYWHEEL


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