Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Plus 8 Clutch

I think mine might be failing, it is sometimes hard to get into gear, particularly when hot. When I stopped at lights I tried to change down to second and it would not shift out of gear bu th engine stayed running, no burning smell from the clutch but had to stop the engine in order to move the lever.

On arrival at home checked the reservoir and it seems full.

Any ideas?

Read this

What year Plus 8 do you have?

When did you last flush and change the clutch fluid? What type of fluid are you using?

As well, try this out for us. Put your car on the level and engage the handbrake (if it is not working well, place the car with its front wheels against the sidewalk). Put your car in first and slowly release the clutch. Note for us when or how much pedal movement is necessary for the rpms to start to drop.

Lorne

Sorry for delay.

Plus 8 is 1992 with 3.9 l engine.

With car on level surface and in gear with handbrake on, lifting clutch pedal brings rev drop after about 2.5cms (1 inch) travel.

What does this mean?

Assuming your clutch pedal was to the floor, that is not good. It means your clutch system is not full engaging for some reason. Those reasons in order of likelihood (and hope) are;

1. The system is badly need of bleeding. (10 minute fix & no cost)

2. The system is very badly in need of new clutch fluid and flushing and bleeding. (30 minutes & 2 bottles of DOT 3 or 4 brake fluid)

3. The slave cylinder is going (very common with pre-1995s) (20-60 minutes depending on the access hassles, minor risks, new slave cylinder for 15 GBP and one bottle of brake fluid).

4. The master cylinder is going, (60-90 minutes, new master cylinder for 60 GBP and one bottle of brake fluid)

5. Your clutch itself is going, (12 hours, engine out job, new clutch for 200 GBP)

I am partial to numbers 1 & 2 & 3.

For 1 & 2 I am guessing the system has not been flushed or bled for a long time. (should be done every 2 years regardless of mileage)

N.B. If DOT 5 was mistakenly used at one point, that could destroy the all the clutch hydraulic seals depending on the circumstances.

For number 3, this is the curse of the Plus 8s from 1976 to 1994)

Maurice Owen had trouble fitting the clutch and Sd1 bellhousing into the Plus 8 bulkhead and adjacent crossmember. So to do so, he cut off the offending bellhousing section that held the standard SD1 clutch slave, welded the resultant hole closed and opened up the top of the bellhousing and fit a totally different clutch slave. He also had to create a box at the top of the gearbox cover as the slave arm moves back into the passenger compartment.

This resulted in a number of problems.

a. The clutch slave is above the master cylinder, making it difficult to bleed and easy to develop bubbles.

b. The clutch slave and its bleeding nipple became a pig to access with the array of EFI gear.

c. The slave's arm enters the slave at a non0ideal angle, making quick wear a certainty. I have never seen one last beyond 20,000 miles and most much less. (The solution is to sleeve your slave in stainless.)

All in all it is a very poor design.

[BTW, The later fix was to change the crossmember to a half-moon shape to accommodate the bellhousing and simply slice off the bellhousing section that covers and closes off the housing at the bottom clutch slave. So later +8 clutch slaves don't fail and are easy to replace, but the bottom of the bellhousing is open to road debris.]

Examine your clutch slave cylinder carefully for any sign of leakage. Then flush and bleed your system and try the clutch again.

Lorne

What a marvellous help, many thanks I will investigate further.

One further question however - how do I flush the system?

Hi,

Forgive me for possible overkill..but I have found it always best to give a complete explanation than a short and sweet one.

Automobile hydraulics (clutch and brake) use special fluids. The different types are designated as DOT 3, DOT 4, DOT 5 and DOT 5.1. DOT 5 is silicone based and the rest are borate ester based. (The higher the number the higher the boiling point.) DOT 5 is NOT compatible with the others and switching to and from DOT 5 can cause grave problems. Avoid DOT 5 like the plague. However, once used, you must continue to do so. You cannot safely switch back without changing every bit of rubber in the system.

All brake fluids are designed to resist the absorption of water. That ability fades over time. Brake fluids (in clutch or brakes)should be changed once every 2-3 years depending on how damp your climate is.

Flushing a hydraulic system is simply a term for recylcing out all the old fluid and putting in new. For the clutch, it is done by opening up the system at the clutch slave bleeding nipple and pumping the pedal until the fluid runs a very light amber.

I do mine by emptying the clutch reservoir with a large mechanic's syringe, I then refill the reservoir with fresh brake fluid. I then place a 7/16 spanner over the clutch slave nipple and loosen it a bit until I can open and close it with very little movement.

I then attach a flexible clear tube over the nipple and place the other end in a clear bottle (big jam jar will do) that is filled enough with brake fluid to submerge the end of the tube.

I then open the nipple so the fluid can flow and someone slowly pump the clutch pedal while making SURE the reservoir remains full by topping it up. (If you don't keep the end of the tube submerged OR the reservoir full you will be pumping air into the system.)

You will see the dirty fluid come out and (if your system had air) bubbles in the bottle. When the fluid runs clear and the bubble stop, tighten the nipple enough to close the system, remove the tube and tighten the nipple snuggly.

WATCHPOINT Though innocuous looking, hydraulic brake fluid of any type is the most dangerous fluid for health in the car. If some drops on the car paint, clean it off immediately..it strips paint with great glee. If some of it falls on you or your clothes, clean it off, it strips skin with equal glee.

Lorne

Lorne,

Thank you very much for your excellent help. Delighted with the 'overkill', not overkill in my case.

I will investigate this coming week-end. I have sourced DOT4 fluid from our local motor DIY shop.

Ian
(ponapay)

Better to be safe than sorry.

If you have more questions or need a photo or two..simply shout. It may be delayed a bit as we are traveling in the UK at the moment.

Lorne (likely heading south unless the rain stops)

Lorne,
Emerald Isle is lovely and sunny to-day and forecast to stay this way until next Tuesday at least!!!

Robbie