Engine Freshen Up to this ........

[Rod]

Since my last response yesterday I have thought a little more about the clutch / gear issue. While I am going to go through everything systematically from the beginning again, I am leaning towards a bent clutch fork.

Prior to the sprucing up of the old girl, I had an ongoing issue with the clutch. I think I documented this previously but when I depressed the clutch, I would get a knock, and when I put the motor under load, I could also get the same knock. As it turned out, I had the clutch plate in back to front. I am suspecting this may have put excessive load on the clutch fork and bent it.

While I never had issues with the clutch and engaging gears previously, maybe with the new clutch and pressure plate, it has come back to haunt me. May be with the bent clutch fork, I have now got little adjustment of the slave cylinder pushrod.

Anyway, I will get there at some point. Hopefully it's not in a years' time.

Have a ripper.

Cheers Rod

[ardiesse]

Clutch in backwards.  Been there, done that.  Which machines arc-shaped grooves into the heads of the flywheel bolts, and as my grandfather (a fitter/machinist) was wont to say, "None genuine without this mark".

And now I remember.  The spigot bearing collapsed (early Humpy), and I had to take the clutch off to replace the bearing, and when I put the gearbox back, the clutch adjustment was way off, and I wondered why that was, as I hadn't replaced anything.  Started the car, went to reverse off the ramps, and it made an awful racket as I let the clutch out.  Said a few choice words to myself about paying attention, and then did an engine-out to fix my mistake.  It took less time than working under the car.

Sorry, but I have to ask: Is your clutch still in backwards?

If you confirm that your clutch fork's bent, I have a couple of the indestructible forged FX-FJ ones.

Rob

[Rod]

I am glad I am not the only one to have had a plate in back to front. Interestingly 30 odd years ago, I pulled the box off the motor, thinking it may have been loose flywheel bolts. You would have thought I should have been more observant at the time for the wear on the bolts. Nope, put back together and the knock continued. It wasn't until I pulled the motor for this current rebuild, that it was evident by the wear on the bolts that it was in back to front. How the clutch even worked was beyond me as the pressure plate had significant damage to the internals, not the facing. As for now, I surely hope it's not in back to front Rob. I was a like a carpenter, "measured twice, cut once". But who knows with me. Time will tell.

Last night I used your "wiggle" technique on the pedal pushrod. I am more than confident now that the end play is correct. All this means is I am one step closer to a bend clutch folk.

Thanks for you offer of clutch folks. I have a few but not sure of type and condition. I just need to find them.

Have a ripper.

Cheers Rod

[Rod]

Well, well.

I have taken the slave off the box and clutch fork covers off. It is definitely something inside as the first thing I noticed the the minimal gap between the back of the fork and the gear box house. I would say 4mm. This would not allow an inch travel when the cluch is depressed. I had a look inside to the best of my ability and I don't think the folk is bent when comparing it to another I have.

When I replaced the clutch I also replaced the throwout bearing. I have a hunch that this may be the problem as I have a feeling reading about differences in these. Anyway it is only conjecture as I will need to remove the engine to investigate anyway.




Have a ripper. Cheers Rod

[Rod]

Took motor an box out today to investigate the clutch issue.

1. Stuck Clutch - check. All clear.
2. Bent / cracked fork - check. All clear. Compared against another fork and the profile is exactly the same.
3. Clutch plate - check. Correct orientation. Checked anyway and it can't go the otherway round. The plate is a little different to the original ie: its much more 'beefier" on the side that needs to be opposite the flywheel.
4. Thrust bearing - While they look identical, the was replacement was 2mm short and also 2mm short from the mating serface of the fork and bearing to the face of the bearing. The old old is more thatn servicable, so I will just reuse this.
5. Spigot bearing - check. Mmm, might be the issue. I rememebr investigating another post where the spigot wasn't inserted far enough. I checked and I was able to drive it home another 3mm. I clearly remember doing this when I first installed it and I compared the distances against another crank. I was confident it was in the right spot but possibly not. I had it installed up to where the taper of the crank finished. Now it is in 3mm further than this spot. Gee I hope I haven't put it in to far.

I hope to reassmebly tomorrow I hope.

Cheers Rod

[Rod]

Well that was an eventful exercise.

Motor out and back in and the issue still persists. When I assembled the fork, it was closer to the front of the box when it engages with the pressure plate fingers than with the new throw out bearing. But when I reinstalled I just had a feeling it still wasn't far enough forward. Sure enough, when I put the slave cylinder on I practically ran out of adjustment at the point where I had spec'ed free travel. It just seems if the fork is bent but there was no sign of this and it compared exactly to a spare I had.

I am trying to figure why this would be the case. The flywheel has been machined but surely this minimal amount would not effect it. The only other thing that comes to mind that I may have been sold the wrong kit ie: pressure plate is thinner than standard which would make the fingers closer to the flywhee. I am really only "clutching (like that one) at straws". The only way I will know is by pulling the box again, measure the pressure plate thickness and compare this to an original.

To recap, I can place into gear when the motor isn't running but can't when it is going. I can start it in gear but it wants to run. Interestingly I tried all four gears but can't get reverse when starting. I will adjust again tomorrow but I don't like my chances of getting to the bottom of this.

Have a ripper. Cheers Rod

[Errol62]

Very frustrating Rod. Sorry can’t offer much insight, as I replaced my crash box with an all synchromesh and concentric slave a while ago.


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[Rod]

Thanks Clay. It has me stumped. Looks like engine out again. At least I hadn't reinstalled grill, bonnet etc... Must have thought there was going to be an issue.

All I can gather it is the fork but there is no sign of damage (bent of broken), it s profile is exactly the same as a spare I have (unless its bent but cant see any sigh) and there was no problems when the gears box was previously in before rebuild.

I think I need to do some investigation with the pressure plate.

Here is a photo which shows I am out of adkustment. This is excessive compared to my ute.



As a bonus I adjusted the linkages and now can select reverse.

Have a ripper Rod.

[ardiesse]

Rod,

This is the stuff of nightmares . . .

I have a few original pressure plates, and I can measure their height from flywheel face to pressure plate fingers.  I can even drop the gearbox off "Found Object"s motor and measure dimensions if you want.

I think that with a new clutch plate, the pressure plate fingers should sit essentially flat.

One way you can cheat is to put washers under the clutch fork pivot ball, but you'd most likely run out of thread before the adjusting nuts get into the right position.  I think that measuring the height of the pressure plate fingers above the flywheel face seems like the best thing to do, but you have to go through all the hassle of another engine-out to do it.

A little Googling reveals that the Exedy GMK6021 clutch kit is the right one for grey-engined Holdens.  It has a 200 mm clutch plate, annoyingly 3 mm less in diameter than the original 8" plate, but close enough; and the pressure plate looks like an exact copy of the original Holden one.  If all else fails . . .

Best of luck,

Rob

[Rod]

Hi Rob,

Thanks for your reply and kind offer in doing some measuring for me. Please hold off at the moment. I don't want you to go to this length. Once I get the box and motor out (again) I will do some comparisons with some old kits / flywheels that I have.

Ive looked at a couple of Youtube videos where it said to be on the lookout for clutches that don't disengage which could be due to machining of the flywheel and diaghram finger height of new pressure plates. Mmm this is my current thinking. I have already found the tolerances in the throwout bearings is different. By going back to the original there was a slight improvement in the amount of adjustment that could be had.

Your suggestion of altering the pivot ball height sound a great idea. Please correct me if I am wrong but I seem to recall reading somewhere in all this research, that this adjustment should be considered in the earlier humpy boxes.

The option of a new kit is looking more likely. I just need to be sure the heights are correct before doing so. The one I put in was a Clutch Industries and I am sure it was the 200mm plate. I will see when I remove.

Thanks again. I will let you know how I get on after I wake up from the nightmare.

Cheers Rod

[Rod]

Well time to pull the motor again tomorrow

I have resolved myself to the fact that the pressure plate is the issue. When I read this thread over at the FB EK Forum, it makes mentions that the Clutch Industries (which mine is) is a low profile pressure plate which would explain the difficulties I am having in adjustment.

https://www.fbekholden.com/forum/viewtopic.php?t=22862

All going well I will have a a direction to move forward by tomorrow evening.

Cheers Rod

[Rod]

Well engine and box is out and to be honest I am none the wiser.

I measured the distance from the rear of the folk to the box housing at the point where all free play was taken up. I did this with an old clutch plate and pressure plate and compared it to the new one that I put in. The results are as follows.

Old Clutch - About 8mm to housing.



New Clutch - about 5 to 5.5 mm.


The pressure plate seems to be practically the same as an old one, particularly from the diaphram fingers to the facing of the pressure plate.

Old


New - Yes it is a 220mm plate.


Please note each clutch plate was of a similar thickness. The old one was possibly slightly less.

I measured the machined flywheel with an old one and it is about 0.5 mm thinner.

I think the measurements are marginal at best and I can't see how these minimal measurements would have an impact. One thing that I did notice was that when torquing up the new clutch it took much more effort to torque the pressure plate flat to the flywheel than the old one. I put this down to the internals being more "chunky" than the old one and the old one is used and the tolerances have increased.

I think this is going to be my plan in moving forward.
1. Complete the same measurements again but this time using the other clutch folk I have just to be sure that the current fork isn't bent (I am fairly confident that it isn't though)
2. Order the Exedy Clutch Kit as you suggested Rob, install and complete fork measurements again.
3. Put a washer under the fork ball - thanks Rob
4. Consider die grinding part of the box housing to allow more travel
5. Consider placing two washers (one for each bolt) under the slave cylinder mounting points to allow more adjustment of the adjusting rod. If so point 4 would need to occur I think.

PS: Can anyone tell me how far the spigot bush should go in the end of the crank? Initally I had it where the taper going into the crank concluded but when I last had the motor out I was able to install it further 3mm until the bush bottomed out. I just hope I haven't put it in too far.


This won't beat me.

Cheers Rod

[DougT]

Hi Rob, have you checked the finger height with the clutch installed, maybe the pivot position is incorrect allowing the fingers to sit to low, just a thought.

Doug

[ardiesse]

Rod,

The 2.5 mm difference in clearance from clutch fork to bellhousing translates to a lot more at the slave cylinder pushrod, maybe double or triple.  So you have, in fact, identified the problem: the "low-profile" pressure plate.  Don't put washers under the head of the pivot ball - that suggestion was not meant to be taken seriously.

Your "old" components look to be in quite good condition.  If the linings have plenty of wear left, the driven plate hub is not loose, and the pressure plate face has neither scores nor hot spots, then I'd be inclined to re-use them.

And if the spigot bush is pressed in too far, it's not going to cause trouble.

Rob

[Errol62]

I wonder if you could get the next size longer thrust bearing……


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[Rod]

Hi Fella's, thanks for your responses.

The horse may have bolted as today I ordered the Exedy Kit. I did wonder if a 'longer' throughout bearing was available Clay. Rob, this morning (after I ordered the kit), I came across a number of other pressure and clutch plates which I think would be servicable in addition to the one in the pictures. Now for the embarassing moment.

I have mentioned about minor differences but I supposed they all add up in the end. In my plan, beginning at point 1, I decided to revisit the fork. I found another as well. In comparing the three, the profiles looked exactly the same. There is no visable crack or bend in the current fork. I thought I should try some measurements. What I did was layed the clutch fork on "its back" on a flat surface and in this case it was on a flywheel. I then measured the height of the end of the fork and the also point where the rod goes into the fork. Embarrassingly, I think I have found the problem - a bent fork. There is 5 to 6mm difference between the current fork and the two spares I measured against. My thinking was the same as yours Rob, that this will then equate to more movement than the measured amount. I will assemble using the "new" fork and complete the same measurements as yesterday.

I thought more about this as I had it in my mind that the fork should be right as it was ok when I was last using this box. But on further discussion with myself, the logic tells me that there was every possibility that it was bent because of the "hard clutch" I previously had as the clutch plate was on back to front. The hard clutch to disengage the clutch possibly could have led to the bent fork.

Here is a left of field thought. The two fingers on all of the forks have a groove in them, which could be up to a mm in depth, where they make contact with the throughout bearing. Would it be over thinking it by welding up these grooves and then grind to a flat surface OR are these grooves there from new and are required.

I am feeling a little more confident in moving forward in finding a solution.

I sincerely that you for all of your help. It is much appreciated. I hope the next time I report I have taken the old girl for a run.

Cheers Rod

[ardiesse]

Rod,

If you end up not using the Exedy clutch kit, I'll buy it from you.  I still haven't replaced the slipping clutch in my grey FC.

The wear marks on the clutch fork fingers are just that.  Excessive wear leads to free movement of the fork in the throwout bearing groove, with the risk that the bearing will tend to "ride" the pressure plate fingers.  Increasing the clutch fork free travel from 2 mm to 3 mm will compensate.  But try to use the least-worn clutch fork.  You could weld it up and grind back to the original profile (father did that in his HR actually).  Offer of a forged FX/FJ clutch fork still stands . . .

Oh, and - does your bent clutch fork have marks on the rear edges showing that it has come into contact with the rear side of the hole in the bellhousing?

Rob