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Author Topic: Clutch Problems  (Read 2709 times)

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june2015

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Clutch Problems
« on: April 20, 2015, 11:58:24 AM »
Hi Art. You have helped me in the past and I am sure you can help me on this one.

I have been getting my 66 ĎBí ready to take down off the jacks and down on the road for the summer. Got behind the wheel and the clutch pedal was Ďveryí soft, no resistance to the floor, canít get it in gear and obviously I canít drive it.

Does my car need a new clutch or is it something else? If a new clutch is needed, is it a major production? I have never replaced a clutch, foreign or domestic, is it something a novice can do or should I seek professional help?

Any guidance you could give would be most appreciated. Thanks.

Jeff Sikora
Orland Hills, Illinois
« Last Edit: December 31, 1969, 07:00:00 PM by amgba »

Art

  • chfwrench
  • AMGBA Club Tech Staff
  • ****
  • Posts: 230
  • Memberhsip Number (if known):: 91-10014
  • MG information: '73 red B roadster
Re: Clutch Problems
« Reply #1 on: April 20, 2015, 11:59:29 AM »
Hi Jeff. This could be a frozen clutch disc to the flywheel. Youíd be amazed how little surface rust it takes for this to happen.

However, more likely it is a hydraulic failure. It is hard to tell from your description unless you check a few things first. This is how Iíd start:

- Open the reservoir of the clutch master cylinder and see if the level is down significantly. If it is, youíve likely found the reason the clutch is not engaging, but not necessarily the root cause of the issue. Even if the level is right, that would not be a clear indication the hydraulics are good.

- Check for oil leakage. While this may seem the simple, first step, as it is more obvious, these cars tend to leak fluids while standing, so after a winter in the same spot, some engine oil from the rear seal can easily be confused with hydraulic fluid from a connection, flexible line to the slave cylinder or the slave cylinder seals leaking. Check at both the master cylinder (which usually leaks down the pedal into the interior or down the front of the firewall) and at the slave cylinder (which would make the transmission bellhouse wet and puddle on the floor). Be sure to also check the flexible line to the slave cylinder. It tends to get forgotten over the years and deteriorates to the point that it either leaks or the rubber blocks things up internally (later for that).

- With the car on the ground, leveled oil in the reservoir, set the parking brake and block the tires, put the car in gear, step on the brakes and fully depress the clutch pedal. Then turn the ignition. If it remains locked, repeat with the car in reverse. Sometimes, if the disc is just slightly stuck to the flywheel, this can free it up, though seldom. If the disc is really rusted on or the hydraulics are bad, it will remain engaged and the engine will balk and not turn over. It would also do the same if there is air in the system (again, if the oil level was down significantly) or the cylinders are bypassing internally and the slave not actuating the clutch. Try bleeding the system and do this again before deciding on any action.

- Put the car back on stands high enough that you can get under to see the slave cylinder and itís operation clearly. Have someone sit in the car step on the clutch pedal. If the arm does not move or fails to engage fully, itís likely hydraulics. If it does move freely, fully and easily, then the disc may be stuck to the flywheel and thatís a much bigger job.

- Last and most telling thing to do is to manually move the clutch actuating arm. You may have to remove the slave cylinder to do this (Iíve done this with a cable come-along attached to the chassis/rear motor mount on one end and to the arm on the other), but if you pull the arm and the clutch releases such that you can put the trans in gear and turn the engine over without the car moving or the engine balking (flywheel stuck to the disc), you are pretty sure it is the hydraulics.

The hydraulic system is such that, if there is a blockage or the internal seals wear, the level can be good, but the cylinders will not work. Personally, unless youíve done this recently, Iíd advise you buy the whole kit, replace the cylinders and flexible line and see if that works before tackling a clutch. You would probably need them anyway, the job can be done by any DIY mechanic (though the bleeding can get frustrating if not done right) and the cost is reasonable - less than $100 in parts. Moss actually has a full kit (albeit with a non-OEM type master cylinder) for about $80 plus shipping.

Installation is straight forward, with just a couple of connections and bolts at each end to get the cylinders out and back and the line replaced. Be sure to check the clevis pins for wear and to flush the hard line with air to get any gunk or dirt out before hooking up the new units. Also, Iíd advise to use silicon oil in the system. It keeps the seals and flexible line from deteriorating for a longer time.

A trick I learned with bleeding the clutch system is to use pressure and feed the oil from the slave cylinder up. A Mighty Vac used in reverse (pushing the oil out of the reservoir) or just using a reservoir with compressed air to push the oil in works very easily and usually does it the first time, though you have to watch both ends to not overfill the master cylinder or drive air in from the bottom by running out of oil there. Iíll send you a photo of the rig I made to use with a compressor.

By far it is cheaper and easier to do the hydraulics than a clutch, which requires removal of the engine. And, if you are not already equipped, that is best left to a shop. Just the cost of the lift, etc. could exceed the labor for a qualified mechanic versus doing it yourself. If there is no mechanic around or you are equipped and have done this before, Iíve got it down that

I can have the driveline out, the clutch changed and all reinstalled in about 8 hours of work, or over a weekend, taking a break.

Check out the hydraulics and letís see what you find so we can take it from there.

Safety Fast!
Art Isaacs
Art Isaacs
AMGBA Tech Staff
chfwrench@aol.com

june2015

  • Message Board Member not current AMGBA Club Member
  • **
  • Posts: 4
Re: Clutch Problems
« Reply #2 on: April 27, 2015, 12:42:45 PM »
Thank you for the information on my clutch problem.  To explain the problem, clutch pedal feels very Ďsoftí hardly any resistance to push it. Trying to put car in reverse, I can feel the flywheel moving but wonít stop to let me place it in gear, same with other gears.

As you stated I first checked the fluid level and it was down but not significantly, so I topped it off. Noticed a stain on the driver side floor and assume itís the Master Cylinder as my problem. Before I buy the Clutch Hydraulic Kit can a novice mechanic, like myself, perform this operation ? ( DIY mechanic ???) If not then I will have to seek a mechanic that knows what he is doing. I would rather fork out the cash to get it fixed professionally than attempt it myself and not do it correctly and still have to get someone to fix it.  

Thanks.

Jeff Sikora. Orland Hills, Illinois
« Last Edit: December 31, 1969, 07:00:00 PM by amgba »

Art

  • chfwrench
  • AMGBA Club Tech Staff
  • ****
  • Posts: 230
  • Memberhsip Number (if known):: 91-10014
  • MG information: '73 red B roadster
Re: Clutch Problems
« Reply #3 on: April 27, 2015, 12:43:52 PM »
Hi Jeff. The hydraulic system is very basic. A single line from the master cylinder (next to the brake master) to a slave cylinder on the transmission. Youíll have to be realistic about assessing your own ability, but Iíd venture to say that most shade-tree mechanics can handle it.

The photo is off the Moss Motors site of their replacement kit. Itís called their Clutch Hydraulic Kit Part no. 180-718, about $80 plus shipping, and while not an OEM style master cylinder, this is the best solution.

As you can see, thereís nothing daunting about it. 2 bolts each on the master and slave cylinders, 2 clevis pins (not included) a each end to secure the pedal to the master and the push rod (at bottom) from the slave to the arm (part no. 325-150, $1.25 each) and, of course, the flexible line.
The hardest connection to deal with might be the one from the hard line to the front of the master cylinder, as that faces the firewall from inside the pedal box. Can be a bit tight to maneuver and might be frozen to the old cylinder. There should be a banjo connector on the front of the master that would be easier to remove, but I seem to remember some clearance issues getting it out.

On the flexible line, I address that by cutting the old one in half, leaving one connection on the old slave cylinder and then removing the other half from the hard pipe with the slave out of the way. The hard line is also available (part no. 181-210, about $34 from Moss). I am using the Moss catalog numbers, but all these parts can come from any one of various sources. Moss or Victoria British are just the most complete and available conveniently on-line (respectively, www.mossmotors.com or www.victoriabritish.com).
The real problem everyone has with these is bleeding them. Like I said, the trick I learned is to do it from the bottom up. There are a few twists in the hard line that can trap air trying to bleed it from the bottom by pumping the pedal. Pushing oil up with mild pressure does this the best and even adapting a hand-held pump oil can with a hose to the bleed screw on the slave cylinder can work.

Save what you can for the mechanic. Do the clutch if it comes to that, but what you say now, it sounds more like the hydraulics.

Stay in touch.
Art Isaacs
Art Isaacs
AMGBA Tech Staff
chfwrench@aol.com


 

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