Super Seven S2 Clutch Issues

[TEM]

Now that this new to me car is finally running after decades of slumber, I'm faced with a clutch issue.  I have trouble getting the car into gear with the engine running.  I have rebuilt the slave cylinder and the master is a new 5/8" Girling.  The system has been bled and the clutch has been adjusted per the manual.  I just re-bled and re-adjusted the clutch with no improvement.  Maybe this is why the previous owner had swapped the brake and clutch master cylinders.  I'm looking for suggestions that don't involve pulling the engine.  I know this is a probability but would like to exhaust all other ideas first.

 

There is a red tube that connects the master to the slave.  Is this original?  My Esprit had a similar clutch hose and when the engine would get warm, the hose would expand and it would be difficult to get into gear and grind gears when moving.  The solution was to change this tubing with a SS hose.

[7Westfield]

those red lines have been around for years, generally fine, but nothing wrong with changing it

what diameter is the cylinder they swapped out?

[SENC]

I think you're OK with 5/8 master - lots of debate on whether 5/8 or 3/4 in various places.  Slave should be 3/4.

 

It may be worth checking the length of your slave cylinder rod.  These apparently came in different lengths.  I dont remember the correct length offhand, but lots of discussion on lotuselan.net about this topic.

[TEM]

I tried the 3/4" when I first rebuilt the masters, I don't recommend it.  All of my cars are standard transmission, this one with 3/4" clutch master was extremely heavy.  Slave is 3/4".  Rod length should not make a difference as long as you can screw the dome nut far enough to set the adjustment.  It can only push as far as the slave moves.  Mine is long enough that you can't remove it without first removing the slave cylinder.

 

I pulled the boot off the clutch release arm and was able to see inside to a limited degree.  The fork looks to be straight, the pivot is in good condition and the throwout bearing spins freely. Is it possible to put in a pressure plate that requires more throw than our slaves cylinders put out?

 

Tomorrow I'll make up a length of hard pipe to see if that improves the shifting.

[Dave W]

You might be able to get an inspection camera through the clutch release arm hole, but you will still be limited on what you can see. Look for pieces laying in the bell housing or scoring marks on the housing.

It sounds more like you have something bent or broken i.e. clutch plate or pressure plate.    

[TEM]

I definitely have room for the camera.  The issue with these cheap cameras is quality of picture.  I tried to us it to inspect my gas tank.  Utterly useless.  My first guess was either a damaged bearing or a weak release arm that may be bending when depressing the clutch - could still be.

[jbcollier]

Once the air is bled out, Girling masters are self adjusting.  Where you can run into problems is when there is wear in the pedal and linkage as this will reduce available travel.  So check you pedal and rod bushings and pins for wear.  I have often filled worn linkages by brass brazing and then redrilled to spec.

 

You do know that the pedal position is adjustable, right?  The clutch master should have an adjustable rod so you can easily add pedal travel as required.

[MV8]

The pedal pushrod should be adjusted to where the upper pedal arm is about 35 degrees clockwise from vertical, to help ensure the net pedal leverage ratio is maximized (mid-pedal travel is 90 degrees/arm vertical). An AN3 or 4 line should reduce the pressure loss though the pressure is just a fraction of what brake pressures are. I don't know if there is a ball stud length adjustment to make the most of the forks range of motion. Do you have a three finger or diaphragm pressure plate?

[TEM]

Even if there is play in the pedal to master rod linkage, once the slop is taken up, the master will still be pushed to it's max stroke unless the pedal bottoms out on the firewall.  I'm short so with the pedal adjusted for me there is no risk of bottoming out the pedal on the firewall.  I have very little slop by the way.

 

After careful measurements, I show the following:

Master cylinder rod travel = 1.04"

Slave rod travel = 0.715"

Theoretical volumetric math shows that a 5/8" master with 1.04" travel should yield 0.722" on a 3/4" slave cylinder.  0.715 is pretty darn close to 0.722 so I think I'm getting all the stroke I can.

[MV8]

The pedal has a ratio that rises and falls. It is not fixed throughout the pedal travel. I thought the issue was effort, not stroke.

Edited June 4 by MV8

[TEM]

Pedal orientation to vertical will be where ever my foot can reach it.

 

I'm at the max length of adjustability on my rod which gives me about 25deg from vertical based on iphone precision.  You would have to have really short legs to have 35deg from vertical.  Unless your pedal shape if different from mine.

 

Not sure on the the pressure plate type yet.  I'll break out the borescope and see if I can discern.

[TEM]

The issue I am trying to solve is that I have difficulty getting into any gear with the engine running.

 

The car originally came with the clutch and brake MC swapped where the 3/4" master was on the clutch.  After rebuilding the masters, I tried the 3/4" on the clutch but it required herculean effort to depress the pedal.  I swapped the master to original configuration with the 5/8" master on the clutch pedal.  I have no issue with pedal pressure now that I'm using the 5/8" master.  I'm now thinking that the previous owner had similar issues so he used the 3/4" master on the clutch to give more throw.  His left leg must have been twice the size of his right.

[SENC]

Confirmed my brake master is 5/8 and clutch master is 3/4, for what that is worth.  I have no reason to believe that is not the original orientation, but who knows for sure what a PO has done.  I've found Lotus literature that says the clutch should be 3/4, but have also seen contradictory evidence.  Regardless, I dont thing either size would contribute to your problem.  It is definitely a "strong" clutch pedal with a 3/4 master.

 

I tried to look back on some old threads and notes, and it looks like the incorrect push rod length may have been a master cylinder rod length issue rather than  a slave cylinder rod length issue.  You mentioned a new clutch master, so it may be worth checking it's rod length and comparing that to the old one.

 

Non clutch related, you might check your gearstick turret.  If that turret had unwound itself at all, it may not be putting the lever in exactly the right places.  I had this issue after my rebuild - I'd neglected to add a little threadlock after adjusting gasket thickness to get it situated correctly and engine vibrations had unwound it just enough to keep me from selecting gears.

 

 

[jbcollier]

Shove a pillow behind your back, or shimmy ahead in the seat.  Now push the pedal all the way to the firewall.  Clutch still dragging?

[MV8]

You could have a pedal made to fit you where the master end is a half inch further away from the pedal pivot and offset to make the most of the ratio, as well as longer on the lower end to accomodate a shorter length foot (ball of foot closer to the floor) for more leverage to make a larger bore master acceptable. Could also just fit a 0.700" bore master.

[TEM]

Camera is garbage.  Can't see anything, light source is not strong enough.

 

I'll take a look at the turret.  I hadn't thought of that as a possible shifting issue.

 

With the current pedal setup, I have no problem pushing the pedal all the way in.  It does not hit the fire wall, but it does bottom out the MC.

 

I use the old/original pushrod on the new MC.

 

I could make a new pedal but am I just masking the problem?  The manual calls out 3/4" master for the brakes but there is no mention of size for the clutch.

[jbcollier]

If you can bottom out the master, then that's all she wrote.  There's no need to investigate the linkage or pedal any further.

 

Assuming the slave is ok, then you are looking at the clutch.

[TEM]

The manual under the 100E description says that the clutch slave pushrod moves 2.54mm which is 0.1"  Assuming the throw is the same on the 100E and 109E transmissions,  my 0.715" throw is not enough.  More volumetric math shows that a 0.7" MC will give 0.91" of slave throw and a 3/4" MC will give 1.04" of throw.  This gives some credence to the 3/4" MC on the clutch theory.  However, this assumes the throws are the same.  Given that the transmissions are different it's hard to say the throw is the same.

 

I' going to try pre-loading the clutch by 0.2" just to see if a 0.7" MC will do the trick.

[TEM]

Ignore my previous post.  The 100E and 109E throws are completely different!  0.1" does not equal 1.04"

 

According to the 5/8" Girling MC info I found on line, the stroke should be 1.375".  A big difference from my 1.04".  Substituting this new stroke at the MC would give me 0.96" of stroke at the slave VS 0.715".

 

If my test drive confirms the 0.2" preload solves the problem, I will pull the master and see why I'm not getting the documented stroke length.

[TEM]

Test drive did confirm that 0.2 more inches of throw will allow full disengagement of the clutch. But, the 0.2" of preload also caused the clutch to slip so I will need the full 1.375" of travel from the MC.  Time to remove and disassemble.