clutch woes

[Limey]

Hi all,
I've been searching the SAOCA forums all day for a definitive answer but no luck.
I've just installed a complete clutch system but gears will not engage with the engine running, just grinding from the cogs if I try

Specs:-
NOS Coil spring clutch diaphragm
NOS Big bearing and arm
Short pedestal
5/8 clutch master cylinder NOS Lockheed rebuilt
1'' slave cylinder NOS Lockheed rebuilt
4.5'' slave rod non adjustable
EDIT - The master rod is through the 2nd hole on the pedal ( the one nearest the firewall

Basically the clutch doesn't quite disengage although there is some action right at the end of pedal travel
The clutch plate is not stuck - tested by starting the car in gear on axle stands clutch pedal fully down - the wheels start turning as soon as the pedal lifts a fraction proving that the pressure plate is no longer fully compressed by the diaphragm.

Engine revs drop slightly when pedal is depressed as expected but no untoward noises

I suspect that there is enough drag still happening to keep the gearbox 'live' hence the grinding and failed gear selection. Is this description/assumption correct?

System was bleed to death using a pressurized system (Easibleed) 2 liters bled through
I clamped the slave piston with a 'G' clamp and pedal pressure is rock solid so no air in the system
Observed:-
Travel at the end of the arm was only 1/4''
Slave piston has not reached maximum travel in the bore, it still has 1/4'' before it leveled with the lip

Question - are the bores installed correct? All searches indicate a 5/8 clutch master is correct and that a 1'' slave is typical as is the 4.5'' slave rod for an SII

It looks to me that I need a little more more travel from the slave piston. Mathematically a smaller slave bore will give me that travel but before I go there I need to know what am I not seeing here??

Anyone been here before? All help greatly appreciated!

EDIT - I ought to add that although the pedal was rock hard there was no resistance for the first half of the pedal travel but it went solid at the half way point of travel. This suggests that the issue is at the master cylinder in that not enough piston travel is occurring - Any thoughts?

Oliver

 

[Tom H]

What side of the bellhousing did you mount the slave to? It should be bolted to the back side. What Series Alpine is this?

 

[Limey]

Hi Tom,

Series II ( I should have said) It's on the transmission side. The issue is not that the slave piston gets to full travel, it just doesn't travel far enough along the bore

Oliver

 

[DanR]

Oliver, Things like that will wear you completely out! Sit back a bit and relax.

I am trying to think thru what you have POSTed. At the moment I have no answer, will think...?

Maybe we /you can get someone to see this POSt that may have had similar problems,

DO you have a spacer between the Cylinder and the firewall? Sounds as if you need to cut down on travel...?

 

[jfcroni]

Good call on the firewall spacer behind the MC... do check that. Nice call on the slave cylinder mounting too... It does look like it should go on the front side of the bell housing... but it goes to the rear of it. What was the original problem or reason you did the work? Did you have any issues with the pilot bearing? If the pilot bearing is tight, it will keep the pilot shaft turning when it should not... like when depressing the clutch. Do you have a hard hydraulic line from MC to SS?

 

[bernd_st]

Hi Oliver,

the clutch master/slave dimensions sound OK from memory. Even though the slave should be a 1inch GIRLING and not LOCKHEED, but would assume this being a typo. Actually S2 used the long body type same as later series rather than the short body type on Series1. So hope you have the correct one.
Just checked the WSM and it states a longer clutch master fork used from S2. With the latter one the pin sits approx. 1/4" closer to the pedal. You may check whether your Master is using the correct one...

 

[Limey]

Thanks all,

Its a full restoration. Long body slave (Lockheed slave at the moment but Girling spec noted although I thought I read somewhere that brakes were Girling but clutch was all Lockheed?). NOS/new everything including 3/16 hard pipe.

MC rod gets full travel at the moment so a spacer not needed?

everythinhg indicates that I just need 1/4'' more slave piston travel

I can get a 7/8 slave which will be an improvement ( I don't have the maths to calc how match improvement though but an easy test.

However, being stubborn I'd prefer to know what the issue is

Oliver

 

[bernd_st]

Ok noted. Think no spacer under the clutch MC. Here is a picture of an all original S2 clutch MC for your reference:



Converting to a 7/8" is possible but not a real option since it will also increase the pedal force. I'm suspecting the slave rod, but don't have a proper reference on hand currently.
Appearantly it was an issue on S2 since on my car where the pictured MC came off somebody also created a "homemade" solution. Actually there was a rod extension featuring a hollow tube with one end closed to increase the rod length. Remember that I've also seen adjustable rods. How about simply increasing the rod length a bit ?

 

[Bill Blue]

How much pedal travel before the slave starts to move? I would not go to a 7/8" master, but certainly would try 3/4"

 

[mikephillips]

Here is another possibility. The early clutch used a taller pressure plate assembly resulting in a shorter pedestal for the clutch release bearing arm. What I've seem supplied is the slightly shorter pressure plate used in the later cars for all series, which requires a taller pedestal to move the arm slightly towards the engine. If you had the early clutch to start and replaced it with a later version, then the release bearing can't move far enough forward before hitting the limit to fully release the pressure plate. CAn't see what you had before from here, but something to check as well.

 

[George Coleman]

Have you checked the possibility of engine thrust bearings

 

[Limey]

Thanks for all the advice and pics. looks like a MC rod length of 90/100mm. I'll check mine tonight. I'll also see if I can see the height of the clutch diaphragm. I am using the short pedestal for coil spring clutches and understand that the tall pedestals where for finger clutches only?

Importantly the lever end is only moving 1/4'' instead of 1/2'' and therein lies the issue
Knowns
Correct Coil spring clutch diaphragm not finger clutch
Correct Big bearing
Correct Short pedestal
Correct 5/8 clutch master cylinder
Correct bore 1'' slave cylinder
Correct 4.5'' slave rod non adjustable
No air in the system

Incorrect
Arm end travel of only 1/4''

Unknowns at the moment
Actuating arm length I know the Svs had a smaller bearing but did the arm length change over the series
Diaphragm depth
MC rod length
Is the release bearing travel being stopped at 1/4'' or can it travel further? I have a plan to test this tonight

If any one can help me with the first 3 unknowns that would be great!

Cheers

Oliver

 

[Limey]

Have you checked the possibility of engine thrust bearings

It's a professionally built engine by a marque specialist but no I haven't although I did see it mentioned during my searches. Perhaps I should just to eliminate the possibility

Oliver

 

[George Coleman]

Is the clutch pressure plate old or is it a newer unit , I say this as I had a early PP go weak on the springs. I went to a MGB pressure plate and the problem went away.

 

[Limey]

Its a New unit from a long standing Alpine supplier

 

[sunalp]

Oliver,
When working on this S2 currently, the clutch arm was bent. It wasn't readily identifiable, but when I had someone
push the clutch pedal and I was able to watch the movement of the arm, it was hitting the bell housing
and popping the slave cylinder piston, too much travel. Perhaps yours is bent in the opposite direction not
allowing the arm the appropriate travel?

Just food for thought.

Cheers!
Steve

 

[Limey]

Good point but how does an arm like that get bent. Must have taken some force...

 

[jfcroni]

Did you replace the old type MC (with canister) with a newer type?

 

[Limey]

Did you replace the old type MC (with canister) with a newer type?

I'm RHD so it is a one piece unit as Bernd_St's picture

 

[bernd_st]

Let me try to answer 2 out of your 3 unknowns:

1) Actuating arm:

Pls. see the picture underneath
Overall it measures 230mm

3) MC rod length: 85mm ( mushroom back side to fork end)