12 replies to this topic

[GreenMini17]

Ive been having trouble with my 1293 turbo engine. I'm using a grey-diaphragm, pre verto clutch assembly. 

 

 

Firstly, with the engine in the car but not running, with my foot on the clutch I cannot spin the engine over on the starter motor. Secondly, with the engine ticking over at about 1,000 rpm, if I were to put my foot on the clutch, it stalls/stops the engine running.

 

I now have the engine out of the car and with the gearbox and clutch off I have measured the end-float of the crank. Putting a feeler gauge between the centre main crank web and the thrust I am getting 0.1mm (I think this is 4 thou in old money?) Haynes manual recommends between 0.05mm and 0.076mm, so do I have too much and could this be the cause of my earlier explained issues? The thrusts look to have been installed in the correct way around.

 

I am a little confused as to what is too much, some people are saying more than 3 thou is bad, some are saying anything under 10 thou is fine?

 

The engine will be pretty high power but its not going to be doing more than 1,000 miles a year.

 

If this is fine, what else could be the cause to my issue as stated above? The clutch assembly looks like it was put together correctly, transfer gears and main gear set looks good too.

 

Help!! Thanks!

[ACDodd]

Have you read my article in this months miniworld? Correct setting of the clutch will sort this issue. 4 to 5 thou is good for revved motors.


Ac

Edited by ACDodd, 14 April 2014 - 04:40 PM.

[The Principal]

too much throw on the clutch arm, go back to the basics with the clutch adjustment as your forcing the crank hard against the thrust washers, also avoid starting the car with it in gear for the same reasons it prematurely wears the thrust washers.

[GreenMini17]

Thanks guys! I thought i had set the clutch up properly, maybe not. Lets hope that resolves it. I shall be buying the latest issue of miniworld then!

[ACDodd]

If it's too much throw the problem will happen at the lower pedal point. If it's a diaphragm issue it will happen towards to top of the pedal travel.

Ac

[Cooperman]

As a note on this, I once built a 970 engine and just could not get the clutch to set up properly.

In the end, after stripping it all down again, I discovered that the special non-OE clutch competition diaphragm was 'bent' by a few thou, thus preventing accurate setting.

If you can't get it right, and maybe as a precaution, you might put a DTI on the diaphragm and slowly turn the engine over.

In this case, however, it does sound like it is a settings issue.

Undo the overthrow nut and the associated lock nut by a few full turns. Set the stop bolt to a gap of 0.020". Try starting it like this before re-setting the overthrow nuts. The biting point of the clutch should be the mid-third of the overall clutch pedal travel.

Once that is OK, re-set the overthrow nut and lock it in the correct position.

[GreenMini17]

If it's too much throw the problem will happen at the lower pedal point. If it's a diaphragm issue it will happen towards to top of the pedal travel.

Ac

From memory, the engine stalled once my foot was almost on the floor, it didnt stall immediately as I depressed the pedal. I set the clutch to the haynes manual specs but i guess it differs with what set ups you have? Does anyone have a clear and concise way to set it correctly?

[ACDodd]

Has the clutch fully disengaged Before the engine stalls?

Ac

[Cooperman]

Clutch Setting sequence, pre-Verto:

 

First of all slacken off the overthrow nut and its adjacent locknut but several full turns.

Now check that when the clutch arm is pressed fully down the linear movement at the top of the clutch arm is between 0.50" and 0.60". (if not further investigation is needed into the hydraulics).

Disconnect toe clutch return spring which goes from the arm to the end of the slave cylinder.

Pull the arm as far as it will go towards the R.H. (i.e. driver's side n a RHD car) inner wing and set the gap between the arm and the small stop bolt to 0.020" and lock it at that.

Press the clutch down to check operation. Start the engine and check that the pedal 'bite section' is in the middle third of its travel. If you want the bite point slightly higher or lower, this is the time to make minor adjustments. 

Assuming all the above is OK, get an assistant to push the pedal fully down. With the pedal down, screw the overthrow nut in until it just touches the clutch cover.

Release the pedal and screw the overthrow nut in a further 1/2 a flat (that's 1/2 a flat, not 1/2 a turn!).

Use the overthrow lock nut to hold it in that position.

 

Your clutch is then correctly set. I hope this is helpful.

 

By the way, you should never start a Mini with the clutch pushed down, especially with a comp. clutch, as that shags out the thrust bearings. Also, never sit with the engine running and the clutch down for more than a few seconds. At the start of a rally test I press the clutch down and engage 1st gear at the count of '5 seconds', then push the revs up to c.5000 and at 3-2-1-GO I drop the clutch in whilst flooring the throttle. That way I minimise thrust bearing wear. On the road I change up & down without using the clutch to reduce thrust bearing wear (call me paranoid!).

[ACDodd]

If you set the diaphragm spring as per article, you thrust bearing life will be greatly extended,

Ac

[GreenMini17]

Clutch Setting sequence, pre-Verto:
 
First of all slacken off the overthrow nut and its adjacent locknut but several full turns.
Now check that when the clutch arm is pressed fully down the linear movement at the top of the clutch arm is between 0.50" and 0.60". (if not further investigation is needed into the hydraulics).
Disconnect toe clutch return spring which goes from the arm to the end of the slave cylinder.
Pull the arm as far as it will go towards the R.H. (i.e. driver's side n a RHD car) inner wing and set the gap between the arm and the small stop bolt to 0.020" and lock it at that.
Press the clutch down to check operation. Start the engine and check that the pedal 'bite section' is in the middle third of its travel. If you want the bite point slightly higher or lower, this is the time to make minor adjustments. 
Assuming all the above is OK, get an assistant to push the pedal fully down. With the pedal down, screw the overthrow nut in until it just touches the clutch cover.
Release the pedal and screw the overthrow nut in a further 1/2 a flat (that's 1/2 a flat, not 1/2 a turn!).
Use the overthrow lock nut to hold it in that position.
 
Your clutch is then correctly set. I hope this is helpful.
 
By the way, you should never start a Mini with the clutch pushed down, especially with a comp. clutch, as that shags out the thrust bearings. Also, never sit with the engine running and the clutch down for more than a few seconds. At the start of a rally test I press the clutch down and engage 1st gear at the count of '5 seconds', then push the revs up to c.5000 and at 3-2-1-GO I drop the clutch in whilst flooring the throttle. That way I minimise thrust bearing wear. On the road I change up & down without using the clutch to reduce thrust bearing wear (call me paranoid!).

Thanks so much for this. Very detailed and very clear! I appreciate your help on this. Once the engine is back in i will follow this set up religiously! One question though: where am i measuring the linear movement at the top of the clutch arm from and to? 1/2" from where to where? Thank you again!

[Cooperman]

The 0.5" movement is the distance the very top of the clutch arm moves from its engaged position to pedal fully down. I just use a 6" steel rule to measure it and I get someone to press the pedal down whilst I hold the ruler. When you get to do it, it is very straightforward.

[GreenMini17]

The 0.5" movement is the distance the very top of the clutch arm moves from its engaged position to pedal fully down. I just use a 6" steel rule to measure it and I get someone to press the pedal down whilst I hold the ruler. When you get to do it, it is very straightforward.

Thank you, that makes perfect sense now :)