Knock when clutch pedal depressed.

[modelAtony]

I'm going to say your ring gear has gotten cocked and is hitting and grinding on a spot in the bell housing. This will start to show up as a little knock and get worse. that's my story and i'm sticking to it. have fun modelAtony Lafayette, LA

[Randall]

I'm with George,bet the starter ring is moving,mine does this about one time a year, I pull the starter and take a hammer and punch and drive it back ,it only has to move a little to start hitting!

[ian Simpson]

Originally Posted by George Miller

There is one more possibility. The flywheel ring gear might be moving towards the back of the engine. If the ring gear has been changed, as with a lot of reproduction parts they did not get it right. The ones that I have used have to big of a ID. This will make a noise when you push in the clutch if it is moving.

Today I was able to get back at the knock problem and found the following:

The crankshaft does move when the clutch pedal is depressed.

The starter bolts were of three differing lengths, one of which rubs on the ring gear when the clutch pedal is depressed.

The ring gear can move on the flywheel.

From this I surmise that:

The first occurrence of the knock (two years ago) was caused by the worn thrust bearing allowing the flywheel to contact an oversize starter bolt.

Changing the starter resulted in the bolts being moved to different positions and a shorter one replacing that which was striking the flywheel thus stopping the noise.

The bendix on the new and stronger starter hammered on the back of the ring gear until it was striking the starter bolt boss inside the flywheel housing restarting the noise.

Solutions:

Short term - a big hammer knocked ring gear back into correct position, all starter bolts replaced with ones of correct length.

Medium term - replace ring gear (and flywheel if necessary)

Long term - rebuild motor with crankshaft endplay corrected.


Thank you for all your help.

PS. Tbirdtbird - what the heck is a derf meter?

[Tom Wesenberg]

If you remove the flywheel and pressure plate be sure to mark them so they can be replaced in the same location relative to the crankshaft.

[George Miller]

You might want to pin the the ring gear to the flywheel. The new starter Bendix will do it to a new ring gear again. The ring gears that I have installed are to big for the flywheel.

[ian Simpson]

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Will do Tom, thanks for the reminder.

George thanks for the suggestion about pinning. I was feeling really lazy and considering pinning by accessing through the starter hole, but sanity has prevailed and I will do it properly.

[29er]

Originally Posted by George Miller

You might want to pin the the ring gear to the flywheel. The new starter Bendix will do it to a new ring gear again. The ring gears that I have installed are to big for the flywheel.

Exactly how is this done (pinning the ring gear to the flywheel)?? And, can it be accomplished thru the starter hole without removing the flywheel?

Thanks

[George Miller]

Originally Posted by 29er

Exactly how is this done (pinning the ring gear to the flywheel)?? And, can it be accomplished thru the starter hole without removing the flywheel?

Thanks

I did mine through the starter hole. I used 1/8 dia. roll pins. Drilled on a angle at the edge of the ring gear into the flywheel. Made sure I went the same depth on each hole and spaced them even around the ring gear. So it would stay in balance.

It would be best to do it with the engine out. But if you are real handy with a drill it can be done through the starter hole.

Since then I use set screws on the ring gear when I install a new ring gear.

[29er]

Thanks George! It sounds like it may be best to do this before balancing the flywheel. To pin it after it's been balanced and still in the car may upset the balance and lead to other ills. Sounds like the best method would be to remove the flywheel, pin the ring gear to it, rebalance everything and replace it in the car.... a bigger but better job.

Mike

[George Miller]

I agree best to get it rebalanced.