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MG MGB Technical - Weird Clutch pedal shudder

Can anyone tell me what this might mean?

I just noticed today that my clutch pedal feels strange when I push it down. It functions perfectly, but there seemes to be a mild pulsing or shuddering that I can feel through my foot. It's very subtle, and seems to happen only when depressing rather than releasing the clutch, most noticable at about 1/2-2/3 down. So now I'm wondering, was this always there but I never noticed it, is this new or am I just imagining it?

Clutch system background:
1. 1974 Chrome bumper roadster.
2. Entire cluch system replaced/repaired by me about 2 years, less than 2k miles ago. Used top quality Borg & Beck kit from Brit-Tek.
3. Flywheel resurfaced.
4. All bolts torqued to spec and all stamped sheet-metal nut retainers replaced.
5. Clutch hydraulic cylinder rubber replaced, (Master and slave rebuilt). As I recall, the metal cylinders appeared to be in good condition.
6. New clutch hose.
7. Castrol LMA fluid is clean & clear and topped off.

Clutch has worked perfectly since rebuild. The subtle pulsing/shuddering feeling happens only when engine is running; perfectly smooth feel when engine is off.

The last observation leads me to believe that if anything, this may be a throwout bearing issue. Please tell me this isn't the throwout bearing starting to go!

Thanks very much for any advice.
Tony Grasso

Good Morning

I had a few moments free time this morning so did a quick search for 'clutch pedal pulsating' and came up with a couple of sites.
http://www.tpub.com/basae/93.htm
http://www.exedy.co.uk/bearings.asp

FWIW

Bruce
Bruce Mills

Is this as you push it down? Or when it is fully down? In the latter case mine did something similar, so I just didn't push it all the way down! Eventually the release bearing broke as the casting had been rubbing on the clutch cover plate and wore through.

In the former could just be stiffness in the mechanical linkages at either end. They usually get no lubrication, and the pedal, push-rods and clevis pins wear which can cause roughness. Wear at the top also causes a low biting point.
Paul Hunt 2

Got the same problem with my '79 BGT. Replaced the clutch (Borg & Beck) and had the flywheel resurfaced. The work was done 6 years (3.5k) ago and I noticed the pulsating as soon as I put the car back on the road. It's a fairly light pulsating and occurs when the pedal is about halfway down. I assumed it was either a poor resurfacing job (out of true) or some sort of misalignment of the clutch parts.
Brian Shaw

Tony,

first of all i would check the linkage and renew the clevis pins and the rods at the slave and master cylinder if wear is visuable.
Having replaced the cluch just 2 years ago, you might have choosen a ball bearing mechanism to replace the carbon bearing. If so, the pumpimg can be generated from a faulty ball bearing too.

If no mecanical faults in the mecanism of the linkages can be found, you should check out the fly, clutch and the bearing and its support again, altough this means to pull the engine again.
Safety Fast! ... think about it ... and keep us posted, please.

Ralph

Ralph

This thread was discussed between 19/05/2007 and 30/05/2007

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