Cobra 427 Build

[KugaWestie]

1 minute ago, Captain Colonial said:

That sucks Gary, sorry to hear this.  I’m amazed the method both you and I have used to free the clutch hasn’t worked.  Is there an inspection plate on the bell housing you can remove to look in and see what’s happening?

 

No there is no inspection plate.

 

I could try winching it onto the trailer and taking it to a bit of private land to try freeing the clutch by excessive throttle use, but then there is this little niggle in my mind that there maybe something else causing the issue (no idea what though) so that is why I have resigned myself to taking it apart. Once the pressure plate is off then I will soon see if the clutch plate is stuck or not.

[Captain Colonial]

It’s the best thing to do, even if it’s the biggest pain in the  imaginable.  That V8 has enough torque to lay waste to the clutch.

[corsechris]

Things to check, in no particular order....ranging from common to clutch-that-straw.

 

Friction plate in backwards.

 

Plastic pivot block for release arm missing or broken.

 

Metal slipper blocks on release arm missing or broken.

 

Excessive machining of flywheel leaving insufficient clearance between flywheel bolt heads and friction plate hub.

 

Gearbox input shaft seized into spigot bearing.

 

 

i did a clutch on the Alfa 155 V6 I had some years back. Everything went back together as it should but when it came to it, it was dragging badly and making nasty noises. It being the end of a day spent putting engine and box back in, I decided to just give up for the day and was resolved to taking the engine back out. A big job on that car. Come the next morning, started it up to move it back into place for work to commence and didn’t actually realise it had miraculously fixed itself overnight until I’d finished shunting it and turned it off.....never did find out what had taken place but it worked perfectly from that point forward.

[Alan Cutler (Adge) - Dorset AO]

That's a blow Gary, feeling for you! Hope you find something obvious!

[KugaWestie]

Well I have decided to have one last attempt before taking it apart.

 

So the car is pointing towards the road, it Is on the ground and has 20psi in all the tyres. My next thing is to move the Cooper S and trailer out of the front garage and put them out of the way. That will give me approx 18m from where it stands to the edge of my drive. 

 

The plan is to stick it in gear and try and start it so it is rolling, Then dip the clutch and stamp the throttle to hopefully free it. If it doesn't free then I need to hit the brake pedal pretty damn quick!

 

If that does not work I am going to winch it onto the trailer, take it to a bit of private land and repeat the procedure but at higher revs/speed.

 

If that doesn't work, it will be dismantle time

 

[Kingster]

We need a video of this Gary 😁

[KugaWestie]

1 minute ago, Chris King - Webmaster and Joint North East AO said:

We need a video of this Gary 😁

 

Not the first effort on the drive we don't, I will have to be on my ackles to deal with it in 18m, never mind worrying about a camera.

 

If we get to phase two I might get something

[Kingster]

I was sort of kidding - but best of luck mate!

[KugaWestie]

2 minutes ago, Chris King - Webmaster and Joint North East AO said:

I was sort of kidding - but best of luck mate!

 

I think it might be my first brown trousers moment with this car 

[Captain Colonial]

One year I did have to resort to doing it in 4th on axle stands and get it up to 60 before stomping on the brakes several times.  Scared the living crap out of me, but it worked.

[KugaWestie]

3 minutes ago, Captain Colonial said:

One year I did have to resort to doing it in 4th on axle stands and get it up to 60 before stomping on the brakes several times.  Scared the living crap out of me, but it worked.

 

I could do with an extra foot really so I can have one on each pedal 

[KugaWestie]

Having thought about things again, I decided against trying to drive the car to free the clutch. I was struggling to believe that the clutch plate would be stuck onto the flywheel as I had checked it and made sure it wasn't only a few months earlier.

 

So over the last two evenings I have split the gearbox away from the engine whilst still in the car to see if there was anything obvious wrong. When I undone the pressure plate bolts and removed it the clutch dropped straight out!

 

But whilst disassembling things the clutch fork did fall off its pivot point. I know this was not loose before as before taking things apart I checked the push rod operation of the fork to make sure the release bearing was sliding on the shaft up to the pressure plate and then stopping due to the resistance of the plate. So anyway I refitted the fork and rechecked the operation.

 

Last night I put the clutch/plate/gearbox back on. Then fitted the slave cylinder. At this point I was able to check the clutch operation by simply putting the box in gear and turning the output shaft to see if there was resistance or not with the clutch down.

 

It was disappointing to discover that nothing has changed. Still a very light pedal and no clutch disengagement.

 

With the clutch plate eliminated my focus then turned to the master and slave cylinders. After some testing with eldest son working the pedal and me laid under the car, I have come to the conclusion that the master cylinder has to be undersized, and therefore not giving me enough piston movement to push the rod far enough to disengage the clutch.

 

To prove this my plan is to temporarily tape a nut onto the end of the push rod to make it approx 5/6mm longer, and then refit the clutch slave and retest. Hopefully this will work.

 

If it does, I then need to decide whether to change the master cylinder to a larger bore or permanently extend the push rod. A larger master cylinder will make the pedal heavier, so my first preferred option would be to try and extend the push rod, but I need to come up with a robust way of doing this.

 

[KugaWestie]

With a bit of fiddling around this evening I made some progress.

I taped an m6 nylock nut onto the end of the pushrod and then fitted the slave. Operating the pedal still did not disengage the clutch. Pedal was very light still.

So I doubled up the m6 nuts, which extended the push rod by 15mm. With a fully depressed clutch pedal and the gearbox in gear I could rotate the gearbox output shaft by hand and could feel the clutch plate rubbing on the flywheel so it had started to disengage. The pedal was still very light though.

But I am getting somewhere.

I think the main problem is the master cylinder is undersized at 0.7.

My plan now is to source a 0.75 master cylinder (hopefully at stoneleigh this weekend) fit it and then test again

[Stu Faulkner]

Any idea what size the original Rover slave cylinder was?

[KugaWestie]

8 minutes ago, Stu Faulkner said:

Any idea what size the original Rover slave cylinder was?

 

I am still using the RV8 slave cylinder, and it is 0.875" diameter