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MG MGA - Clutch sound
|I'm getting a kind of scraping sound when depressing the clutch while engine is running. |
As I start to push down on the clutch pedal and for most of it's travel towards the floor, the sound is not there; it's only during the last inch or so of clutch travel before the pedal is fully depressed that the sound is heard.
The clutch push-rod is adjusted correctly as per manual.
I don't keep a record on such things, but I doubt that the throw-out bearing has more than 2,000 miles on it.
Any thoughts on the cause?
|Well, there are really only three real choices....The throwout, the pilot bushing, or the pressure plate...|
Did you replace all the parts 2000 miles ago?
Has it just started doing this?
|Edward Wesson 52TD|
|What about the clutch disc...did you replace it at the same time?|
|Edward Wesson 52TD|
|Does it do it all the time?|
I get a similar experience but only when I am backing the car out of the garage after not driving it for a week or so, then it is fine. I replaced everything in the clutch 2 years ago but it did it before as well. I don't worry about it but I am curious. I have wondered it is slight rust on the pressure plate to graphite ring surface like you can get with brakes on first application.
|I have had a similar problem a few years ago, The symptom is a squeal just as you take up the drive when the engine is cold. It was particularly pronounced in the winter. It always goes away when warm. |
My problem turned out to be the spigot bush in the flywheel. it was worn about 0.040" oversize. A new bush has fully cured the problem.
|The pressure plate, disc, throw-out bearing, and pilot/spigot bushing are all under 2K miles.|
Too bad I can't send a sound file; scraping doesn't quite cut it; neither does grinding; a scraping squeal maybe? Temperature changes seem to affect the way it sounds, along with the volume of the sound. Higher temp = louder sound.
The sound is not evident for almost all of the pedal travel; and does not come into play until the clutch pedal is literally about an inch from full travel to the floor, and the sound remains as long as the pedal is held within that last inch of travel. Releasing back past that inch and the sound ceases throughout pedal travel to full release.
I remember hearing the sound a short while before shopping the car in the garage in order to go through the hydraulics. That was a year and a half ago. I fired it up a couple days ago and have driven it perhaps 3 or 4 miles since finishing that job.
|The clutch release arm rides on a pivot bolt with a bronze bushing. If that pivot joint is loose the release bearing can wander off center. At certain positions in the arm travel the release bearing may touch the gearbox input shaft where it can make noise while rubbing on the splines. That could make a scraping noise at full pedal travel.|
A loose spigot bushing in the crankshaft or worn splines in the clutch disc can allow the shaft and/or disc to orbit or wobble, which makes a rather loud and obnoxious screaming noise accompanied by notable vibration. This commonly happens as the pedal is being raised and the clutch is beginning to engage, although it can also happen with the pedal fully depressed.
|Could it be worn crank thrust bearings?|
|I had this problem when I first restored my car in 1989. We looked at evey possibility and all was correct externally. The car drove fine, just made a scraping / rattling noise for the last little bit of clutch travel. We tried shortening the pushrod at the slave which resulted in the slave piston popping out, we adjusted the rod at the MC, which led to crunching in all gears as the clutch had too little travel.|
When I finally removed the engine to look at the clutch, we found that the coil springs in the friction plate (which was correctly mounted) were rubbing on the levers of the pressure plate, and had worn a clearly visible groove in the levers. The clutch was a brand new Lockheed unit. Changing to a different brand solved the problem - and I think Moto-build even swapped it free of charge because they had never seen the problem before.
But apart from the scraping noise, the car drove jut fine and I lived with it for the first season after I finished the car.
|Love it... Thanks, all, for your input.|
Well, that nails it; out comes the engine.
Will let you know, hopefully before the next year or two, what the problem was..
|Dominic; in case the info could come in handy later on, do you remember the name of the clutch brand that solved your problem?|
|Sorry Rick, after 24 years that detail escapes me....|
|Are you still using the MGA clutch?|
|I switched to a B clutch and a Ford gearbox a few years ago.|
|Funny that was just going to search for this problem, have the exact sound, I have the five speed box fitted cant remember when it first started does not seem to get worse after just doing a 600ml trip.The only way I can describe it ,sounds like a spring scraping not a heavy metalic sound |
This thread was discussed between 20/07/2013 and 30/07/2013
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