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MG MGF Technical - Clutch malfunction, 1.8 VVC.
|I need to give a bit of history on this, so, are you sitting comfortably? Then I'll begin.|
'98 R 1.8 VVC 88,000 miles.
Recently sufered a clutch master cylinder failure and while my 'Ace Wrench' was checking and testing after replacing the component he wasn't happy with the mechanical side of the clutch. Turned out that one of the springs in the centre plate had fallen out in several pieces. He replaced the clutch plate, cover and release bearing and while he was at it I asked him to replace the master cylinder as well. I know, I know, a bit extravagant but wth.
Since the repair was carried out the bight point has been less than 2" (50mm) off the floor, far lower than the 3 1/2" (95mm) ish that we had enjoyed prior to the master cylinder failure. Bluddy uncomfortable and wifey says she needs a longer left leg.
With the pedal fully depressed and a gear engaged, continue to hold the pedal down, there is no movement in the hydraulics, that is, there appears to be no by-pass of fluid in either cylinder.
Pumping the pedal several times and then engaging gear makes no difference to the operation which suggests there is no air in the system.
We've done about 120 miles in town traffic and a further 120 cross country which we feel should be adequate should any 'bedding in' have been necessary but the problem has not altered at all.
So, can any of you Guys shed any light on the problem, pretty please?
I've looked on Dieter's fabulous site but couldn't find this specific fault mentioned.
Two further questions for you if you are still awake:
1. What is the purpose of the clutch damper and how does it achive it's purpose?
2. Will a 1.6 clutch assembly physically fit in a 1.8 VVC and if so, are the components different in a manner that could cause our problem?
Looking forward to some quality advice, thanks in anticipation.
|A H Price|
This really does sound like a pain in the proverbial. I've not personally come across this problem, but I wonder about the adjustment of the system if the bite point is only milimetres of movement. I have a suspicion that the clutch may have to come out again for investigation :o(
Regarding the rather easier questions:
>> 1. What is the purpose of the clutch damper and how does it achive it's purpose? <<
The damper is, as far as I can tell, pointless. It was later dropped by MGR themselves for later versions of the VVC, and the standard 1.8 and 1.6 didn't have it in the first place. I've removed the one found on Project Shed and replaced the master with a 1.8i item.
>> 2. Will a 1.6 clutch assembly physically fit in a 1.8 VVC and if so, are the components different in a manner that could cause our problem? <<
The clutch mechanism from a 1.6i will be a direct swap. The master cylinder (part number STC100083) is shared between 1.6 and 1.8 models, as you might expect. I can't foresee how a 1.6 master cylinder, which is the same as a 1.8 could possibly precipitate the problems you're having - unless there is a problem with the linkage, and this is unlikely as on recollection, the actuator arm acts directly from the pedal's lever arm...
I suspect a problem with the slave cylinder, and perhaps with the release bearing/linkage.
Please do let us know what the problem turns out to be :o)
|The clutch hydraulics are a sensitive affair on the MGF, caused me many a muttering diatribe. Don't rule out air in the system until it's been bled again, and possibly again, and possibly a third time for luck. Getting air out of the master cylinder (and damper) can take a lot of throughput, and doesn't necessarily give the pumping-up symptom.|
The clutch damper on the VVC was intended to make the engagement more progressive for people without a finely-tuned left foot. Why it was fitted is a bit of a mystery, and I believe the dealer network were advised to remove it if problems arose with the clutch during the warranty period.
Not familiar with the 1.6 clutch, the only difference I know of is the diameter - slightly smaller than the VVC version. It would certainly not be a problem to fit, and the release bearing is the same, and there's no difference AFAIK in the gearbox mechanism, so I'd expect any difference to reflect as a higher bite point not lower.
|Sorry to have left this for so long, Rob and Bandit, and thank you both for your input.|
We've both been pretty busy and she uses the car daily so things don't get done too quick around here.
The circuit has been bled again and she feels it's improved to an acceptable condition. It does feel marginally better to me so it's being used. However,
I intend removing the damper at some point and I'll let you know what happens.
|A H Price|
|Me too a few days ago - low bite point and crunching gears. I replaced the slave cylinder complete (£45) rather than fiddle with a repair kit (seals). Now I can change gear, even into reverse, without noise.|
Fitting is dead easy - less than 90 minutes:-
1) Lift the front bonnet and unscrew the clutch master cylinder reservoir filler cap. Put a piece of thin plastic sheet over the opening, large enough to go over the threads. Replace the filler cap. This helps prevent fluid loss when you come to disconnect the slave cylinder from the hydraulic line.
I used a piece of supermarket bag. Removing the large black plastic finishing panel/cover makes access very easy.
2) Unclip the soft top at the rear and draw it forwards over the head rests. Stop the top from dropping back with a hooked elastic strap - fit the other end to a wiper arm. Unscrew the engine cover plate and remove it to reveal the clutch slave cylinder mounted on the gearbox with two bolts. It's connected to the clutch arm with a clevis pin secured by a wire clip.
3) Use pliers to pull out the wire clip from the clevis pin - and remove the pin. Retain both for reuse. Disconnect the hydraulic line from the slave cylinder, catching any fluid on an absorbent rag. Unscrew the two slave cylinder bolts and the old cylinder can be removed from the gearbox.
4) Keep the fluid input shipping bung in place on your new slave cylinder. Don't mess with the actuating rod either! Offer the entire unit into place and reconnect it to the clutch arm using the old clevis pin and spring clip. Now remove the shipping bung and screw the fluid line into place half tight. Line up the cylinder mounting holes and refit the two mounting screws. Now tighten the fluid line. Check the bleed nipple is tight.
5) Prepare to bleed air and old fluid from the system. I use a one man bleed kit (from Guns*n) - it works for brakes too! Get your spare tyre out and drop it's pressure to 20psi. Fill the kit's pressure tank with Dot4 standard brake fluid.
6) Remove the plastic sheet from the master cylinder and connect the pressure tank's filling line to the master cylinder - it screws on where the cap should be - and connect the airline to the spare tyre. At the slave cylinder, connect the kit's drain pipe to the bleed nipple and hang the free end into a plastic cup or similar receptacle. Open the slave cylinder bleed nipple and watch the fluid/air/muck come through into your receptacle under pressure. Close the bleed nipple periodically to check there's still new fluid in the pressure vessel and empty the old fluid into a larger container. You may as well replace all the fluid - repeat the bleed process until clear (new) fluid is observed coming out of the drain pipe, without air bubbles.
7) Disconnect the air line and the bleed kit at the front. Replace the master cylinder cap, replace the large black plastic finishing panel. Put more air into the spare tyre and put it back.
8) At the rear, remove the bleed pipe and recheck it is tight. Make sure the two slave cylinder bolts are tight. Put some white grease over the clevis pin. Replace the engine cover and screw it down. Reclip the hood into place. Job done.
|Excellent instructions thanks! :o)|
This thread was discussed between 14/03/2010 and 22/07/2010
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