My Ongoing Clutch Problem

DennisR

DennisR

Senior Member
Originally I had a noise when I pressed the pedal. The general opinion was probably a knackered release bearing so I decided to replace the whole clutch. When I got the old one out there was no obvious reason for the noise that I could see, but I went ahead and changed the whole clutch anyway. All put back together and on testing I still have the noise. Took it apart again, checked everything, I could see what the problem is. I put it back together yet again and I have recorded a vid of the sound as best I could, the engine running I press the clutch gently using my hand until it contacts the forks and slowly increase the pressure, the sound starts off as a mild scraping sound and increases to a quite heavy scraping sound is the best way I can describe it.
https://youtu.be/ZapFe7OtZUo
 
At first I thought it was the throw out bearing installed backwards. After looking at Bratton's catalog, they say install with the widest part toward engine, as you have installed it. When you push the pedal the flywheel moves forward, could this movement be letting the flywheel hit a starter bolt thats to long? It has been found here before, I think its the bolt thats closest to the enging block. You could loosen it a few turns and test.
 
starter bolts too long? Crankshaft sliding forward and front pulley hitting something? Does it do it under a load when you drive? Is it better or worse under a load? Have you replaced any bearings in the transmission? My AA would make a clunking noise lightly in neutral but severely worse under a load. Ended up being a faulty trans bearing. Can you " feel" the noise in anything- side of trans, shifter, bell housing, flywheel housing, starter, oil pan, etc. Obviously dont be dumb and put your hand in the inspection hole with it running...
 
At the risk of sounding like a broken record on this issue, my standard first suspicion centers on the flywheel ring gear. This has been discussed many times in the past and more often than not, that's the cause. Remove the starter and ensure that the ring gear is seated firmly and evenly against the flywheel. It must not extend forward past the flywheel ledge. Check in several places throughout the flywheel's arc. There must be no gap between the ring gear and flywheel. If there is, tap the ring gear back into place. If it happens again, stake the ring gear against the flywheel via Allen set screws. I have seen this problem many times in the past few years because in the 1970's and 1980's, low buck vendors sold an off-shore ring gear that was slightly too big. It fit onto the flywheel with little effort, but eventually worked its way forward when the starter gear engaged it. Lots of the those ring gears are still around.
Another cause of such a noise I have encountered was using new flywheel-to-crankshaft flange bolts. The heads were too tall and the clutch disk hub scraped them when the pedal was depressed as the engine ran. This was probably caused by the face of the flywheel being resurfaced in the past more than once, which would move the clutch and disk closer to the bolt heads. I ground down the heads of the bolts and the scraping ceased.
These would be my two major suspects since you already eliminated the clutch itself as the source.
Marshall
 
Marshall has the answer. I had the same problem with a car that came from south america. The ring gear was walking forward in two places, from the impact of the starter striking it. I changed the flywheel and ring gear, and it has been fine since then.
 

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I`ve just removed the starter. The 3 bolts show no sign of contact with the flywheel. With reference to the ring gear I wasn`t able to take a pic but to me it looked ok. I`ve added a rough drawing of what I was able to see, I need to rotate it fully..........enough for one day..................
 

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If you can slide any size feeler gauge between the ring gear and the flywheel, the gear has moved. The ring gear doesn't need to tilt too far forward for it to strike one of the re-enforcing ribs on the flywheel housing. That's what's knocking if the gear has moved forward. It usually doesn't move evenly all at once; rather, one area will tip forward. Then another area and so on, usually one of two places where the starter gear engages the ring gear 80% of the time.
Yes, be sure to check at all 360 degrees of revolution. It only takes one place where the ring gear has moved forward to cause noise.
Marshall
 
I couldn't see a line where the ring gear meets the flywheel, prob will when I clean it off tomorrow.
 
Assuming it is the ring gear moved on the flywheel, here's the solution I have used successfully.
Take out the starter motor and tap the ring gear back toward the shoulder it should sit against. Work you way all the way round and if it moves, you will know by the sound. Continue doing this until you get the solid "home" sound all the way around. Some will have you drill and tap a hole half in the ring gear, half in the flywheel and put a screw in it in several locations around the circumference. I've found a few drops of loctite # 290 is enough. (this is the loctite intended for post assembly application - it wicks into a small gap). With this method, removal of the engine or gearbox is not required.
 
Glad to see you found the problem. Now to roll up your sleeves and create the work space to fix it. Good luck. When you're ready to install the new gear on the flywheel, make sure you have the bbq well heated to cook the new ring gear. Have fun. Jeff
 
Is that a crack, or is it the weld seam?

If it is a crack, it would be the first time I've ever heard of such a thing on any car.
 
John - it`s not as bad as it looks, just a bit shiny, the end of the starter making contact, it has a new type gear. Prob because the ring gear has moved forward.
Thanks Jeff, new ring gear on order, will take it to local engineering workshop for fitting.
Tom, pretty certain it`s cracked, was hoping to have the flywheel off today but the bolts are giving me a hard time, will get back to it tomorrow.
Looks like I didn`t need a new clutch !! or release bearing !! still at least I know I have a good clutch and thanks to tips on here I can do the whole job singlehanded.............................................
 
if its truley cracked it shouldnt take much to tap it off with a hammer and punch as it lost all its gripping power. Make sure the surface the new ring gear will sit on and "clamp" on is near surgically clean. Also make sure the new ring gear doesnt have any burrs or anything that could cause it to hang up upon dropping it red hot on.

Once the flywheel is off you should see evidence in the housing where it was hitting.
 
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