63 replies to this topic

[Ben_Cunnington]

Hi all I’m hoping someone can help me here. So I’ve rebuilt my 1275 engine to a 1310 using MED components. The build has gone well so far, had it started up and running. The carb and timing is set up and running sweet. One final issue I have before I can give her a run out is the clutch. I can’t seem to get it to disengage to locate a gear. Whilst engine is not running I can select all gears. As soon as I start the engine the revs decrease by maybe 100rpm when I press the clutch in and I can’t select a gear apart from first and reverse but even then I get a slight crunch. I’m running a standard crank with an ultra light med flywheel and clutch on a blue top plate. I have a 0.005 gap between the primary gear and thrust washer. Any ideas would be gratefully appreciated. Many thanks in advance

[nicklouse]

how far is the arm moving you need at least 1/2" of travel and the stop gap needs to be about 15-20 thou"

[The Principal]

sounds like basic adjustment is needed,

 

'Cooperman' has excellent write ups here's one - 

 

When it is all re-assembled, undo the big nuts in the centre of the clutch cover. Back them well off.

Then with the return spring removed, move the arm as far as it will go away from the engine and set the gap between the little projection on the arm and the stop bolt head to 0.020". Lock the bolt at that setting.

Re-fit the arm return spring and pres the clutch pedal right down whilst measuring the lateral movement at the top of the arm. It must move a minimum of 0.50" and ideally more like 0.55" to 0.60". With that movement the clutch will operate correctly.

Then, once this has been set correctly, have someone push the clutch pedal down and hold it down. With the pedal held down, screw the inner of the two big centre nuts in by hand until it just touches the clutch cover. Release the pedal and screw it one further flat (that's one flat, not one complete turn). Use the other big nut to lock it in that position.

Your clutch is then correctly set including the overthrow nuts.

It will work (he said, hopefully    )

[Ben_Cunnington]

Thanks for the advice chaps but unfortunately no cigar. I followed the above instructions and got 0.60” clearance on the arm. I’ve also bled the fluid. Seems very strange to me as when I press the clutch it’s obviously creating tension on the lightened flywheel to slow the engine down but won’t disengage the clutch quite enough to select a gear? :/ any other ideas
Thanks again

[nicklouse]

Ok then has the back plate been machined to suit the machining of the flywheel and its spacers?

[imack]

You've got enough throw on the arm then. Have you got the arm adjusted correctly with 15-20 thou clearance and set the throw out stop nuts?
Idler gear shimmed correctly?
Flywheel going too far up crank taper and pinching the 'C' clip and closing up the primary gear clearance?

[Ben_Cunnington]

Yeah so the back plate was all fitted and balanced by MED all I had to do is slide it on and tighten the bolt. Just been up the road with it in 2nd. I was able to locate 2nd with the engine off applied the brake and switched engine on. As soon as I released the brake the car started to creep forward with the clutch fully pressed to the floor.

[Ben_Cunnington]

In reply to imack. I’ve set a 20 thou clearance and set the throw out stop nuts. MED engineering built the straight cut box with idler gear so I can only assume that has all been shimmed correctly. I’m not sure about the flywheel going to far up the crank and pinching the c clip. When installed the c clip I made sure I had between 3 and 6 thou clearance as initially I was getting around 10 thou clearance in an original shim so purchased a new one to close the gap.

[The Principal]

whats the ball on the clutch arm like is it still round in shape or worn? has someone bent the clutch arm?

[Ben_Cunnington]

The clutch arm is a brand new MED clutch arm
Thanks everyone for the replies :)

[imack]

You can check to see if the idler and primary gears are able to spin freely without any major dismantling.
Remove the starter motor and you should be able to see the clutch plate sandwiched between the flywheel and back plate. Witht the box in neutral get someone to press and hold the clutch pedal fully down, you should now be able to easily rotate the clutch plate via the stater hole with a screwdriver, this in turn is obviously rotating the primary and idler gears.

[johnv]

When I had this problem it was because the clutch plate wasn’t moving freely enough on the idler .. I took it apart (again .. don’t ask ..) and cleaned up the splines on the idler and used red rubber grease and all was well ..

[Ben_Cunnington]

Thanks guys. I will give that a go tomorrow and report back :) fingers crossed I can get to the bottom of this one. Can’t wait to hear what these straight gears sound like :)

[imack]

Thanks guys. I will give that a go tomorrow and report back :) fingers crossed I can get to the bottom of this one. Can’t wait to hear what these straight gears sound like :)

Pretty darn loud if you've got sc drops too! Music to my ears!

[Spider]

 As soon as I released the brake the car started to creep forward with the clutch fully pressed to the floor.

 

There's hardly any disengagement at all (which I know you already realise).

 

Pop the timing cover open, turn the engine over (perhaps by pushing the car in gear) until you get a bolt for the diaphragm to line up with the opening for the timing. Take a measurement here from the Bolt head to a reference point (I just use the clutch cover). Have someone depress the clutch and make the same measurement.

 

You need a minimum of 0.8 mm here and preferably 1.2 - 1.5 mm.

 

This will help guide you where you need to focus your attention.  If you are getting this, then the problem likely lay in the Primary Gear. If you are not, then there's an issue with the arm and / or plunger, possibly even a work clutch cover.