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MG MGA - Release bearing
|Well I've got 369 miles on my car since its completion. At about the 300 mile mark I started getting a squeal when I press in the clutch for first or reverse.|
Sounds like a release bearing to me.
The thing is, I don't hold the clutch in while stopped and this is a brand new part as is the clutch and pressure plate.
Any ideas what would be causing this to suddenly show up? The first 300 miles were noise free.
And, any ideas on a cure besides pulling the engine out?
|I would tend to guess at glazing. |
I'm not sure how to address that specifically. In the absence of any other suggestions you could get some clutch cleaner and put the red extension tube up the drain hole at the bottom of the tranny and spray some back in that direction. Have someone push the clutch pedal in an out whilst doing so.
What is "glazing". I'm not familiar with this term.
Glazing is when some contaminant (usually oil) gets on the surface and under heat and pressure it gets embedded in the surface. The surface then loses friction.
In some instances the glazing burns off with agressive shifting. The clutch cleaner will also break down the contaminant.
If it's truely a relase bearing noise it shouldn't matter what gear you select, or if you're in gear at all for that matter. Anytime you press the clutch down at all you're using the release bearing. Do you know what type of release bearing was installed? Normally they are just a carbon faced friction surface, but apparently there are ball bearing style units available. I've never known the carbon faced ones to make any noise at all. Usually with ball bearing release bearings you get a rumbling type sound when they go bad. If you can press the clutch down in neutral and not get a squeal, but get it in 1rst or reverse you might want to consider another problem.
|G T Foster|
|Engine thrust bearing?|
|Loud squeal sound is commonly accompanied by a vibration that can be felt (mildly) throughout the chassis of the car. This would be a rapid chattering of the clutch disc, usually caused by a combination of two or more items, loose spigot bushing, loose splines, contaminated friction disc. You can try cleaning it, but otherwise it is a pain to "fix", involving R&R of the engine for access. See here: http://mgaguru.com/mgtech/clutch/ct_107.htm|
You may also train your feet to avoid the conditions associated with the noise, thereby eliminating all or most of the issue at hand. When you're ready to start up from a dead stop, goose the throttle a little more and let the clutch up a little quicker, slightly in the direction of a jack rabbit start. This will greatly reduce the time the clutch spends in the transition zone where the clutch disc encounters friction slip while it still has space to wobble.
|Christopher, I've suffered the exact same fate as you. I was told it was either the throwout bearing, or the transmission input shaft bearing slipping in the transmission casting. Currently, I hear it when pulling away from a stop with the engine RPMs above ~600. Also when downshifting from third to second (that started about 2000 miles later). Frequently, when in the garage, if I push down on the clutch pedal, and try to put the car into first or reverse, the gears will grind a little and it will squeal like a harpooned penguin. Finally getting it into gear will nudge the car a little forwards or back depending on which gear. Sometimes pumping the clutch helps. Obviously, starting from a stop going uphill produces quite a cacophony. It's been getting progressively worse over the course of 6 years (when the car was completely restored). It happens more often, under a wider range of conditions. I guess I'm just waiting until something outright breaks and leaves me stranded so I know for sure what it is. In the meantime, I still get a lot of admiring looks from people, until I need to pull away from a stop...|
As a counterpoint to what Barney suggests, I've learned from experiance that if I let the RPMs drop, forcing the engine to lug a little when pulling away, it's less likely to make the noise, but I'll try his method tomorrow.
|It is almost certainly the flywheel spigot bearing. My daughter recently had the same problem with her MGC GT. I restored the car and was probably supplied with the wrong type of bush. Ordinary brass bushes grow with repeated use (ie getting hot, etc) and scream when there is a variation between speed of the flywheel and that of the first motion shaft.|
|I would think that the noise is from the spigot bush being a bit dry. Jim|
|So what's the solution to the spigot bushing problem? Just wait until the output shaft bearing starts to leak oil? :-)|
|The solution, unfortunately, is to remove either the engine or the gearbox (or both!), can't remember which is "easiest" in an MGA, and install the correct (well lubricated) bush. Otherwise the screaming will go on, if it is a brass bush it will continue to grow but I have not heard of them doing any real damage (owners generally can't stand the noise and rectify the problem!).|
This thread was discussed between 22/05/2009 and 25/05/2009
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