915 Issue, help requested
 

Hi,

915, 81 sc, usa.

Last fall started having trouble putting shift lever into 4th while driving cold.
New fluid, no help. Issue would come and go.
Did the bushings, coupler, adjustment.
Last week took it out and drove well enough.

Yesterday, reverse out of the garage onto street... can't go into any gear, of course I won't ram it in, but basically locked out of all gears except reverse with grind (but can't remember how long I had the clutch down for before trying reverse), the last gear I was in. Clutch in, clutch out, no difference, still can't get it in. Turn the car off, all gears are back. Take it for a drive, everything normal, but 1/2 hour later can't go into 3,4,5 coast a bit then 5th comes back and everything shifts normally again.

Today. checked 1.0mm unchanged from last adjustment. Removed cable at transmission and used bungee cord to hold up clutch pedal. Checked 1.2mm gap measure as expected. I hooked up the cable again roughly and proceeded to remove the bungee cord holding the clutch pedal up, the pedal sank well below the brake pedal. That's unusual. Asked my helper to push the clutch pedal down so I could remove the clutch adjustment lever bolt as it was rounded slightly. The clutch never came back. There is no 1.0mm or 1.2 mm gap to be had and there is no hope for 25mm travel.

What's going on?

(two years ago with engine out I lubed the fork, so it's not binding, most likely,)

Phil

Rubber hub clutch discs do that when a chunk gets stuck under the pressure plate diaphram. Might be a loose guide fork attached to the inside surface of that 4 nut plate on the trans center housing. Put it in neutral and remove the plate. Oil drain tub ready.

Thanks John,

Checked the guide fork at bottom of trans late last year. Fork was on good. Presently it goes in all gears nicely but still can't get clutch to come back out.
I'm pretty sure the clutch was replaced at some point, when I viewed it from the side two years ago it was the type with the slots in the friction material. Does this more modern type still use rubber?

How about the release fork? Could that be another reason 25mm travel would be impossible at this point?

Thanks,
Phil

John I edited some info that was misleading, 1/2 hour into the drive I lost not only 5th, but 3,4,5. Coasted then 5th went into gear and all gears shifted normally till arrival at home.

Phil, make sure the clutch cable casing isn't collapsing or getting pushed through the firewall, or something weird like that. Otherwise, get ready to drop the engine/trans. and split them to see what's going on.

Hi Pete,
With cable free of clutch release lever the 1.2mm gap between it and the positioning lever is non-existent with the adjustment bolt backed fully out. (the two levers contact each other with cable disconnected and adjustment bolt removed)

This morning tried to remove the two levers, having trouble pulling the clutch position lever out and am taking a minute to think about why, it is binding to the release lever, some tapping didn't change anything. I thought the clutch release lever (the one that hooks to the cable) had some vertical movement so not rusted to the cross shaft, maybe my imagination. Something doesn't make sense.

Phil

Phil,

How much travel (mm) does the clutch cable has now when you depressed the clutch pedal? How close are you from the 25-mm spec travel distance? Thanks.

Tony

Hi Tony,

No helpers to push the clutch in at the moment, but maybe half of the 25mm (.98 inch) would be a guess?... But why with cable disconnected is there no gap between the two levers? The 1.2mm (.047 inch) that's usually there is 0mm. One of the two levers (the one with the omega spring called the clutch release lever in Bentley) or the smaller splined lever attached to the cross shaft is out of position? But which one and why?


Thank you,
Phil

Clutch disc is the culprit

Ian

Thanks Ian,
Can any harm be done by removing the clutch lever at this point? Might as well try and finish that path off. But I have doubts it will be able to go back on, so it's a one way trip.. that's fine I presume?

Phil

you said it shifts fine with the engine off, and won't engine on .
That is the key . If you start the car in first gear can u drive in first ? if so then the clutch is bad .
Not a good idea to drive and have a chance for the clutch parts come apart in motion , damage will occur . Take apart what ever you want , I think the clutch needs replacement
Ian

Took some pictures using a crappy boroscope mostly though upper view hole in trans:

Pict1 Pressure plate.
Pict2 Looking through a pressure plate hole.
Pict3 Springs on clutch disk?
Pict4 Looking at release bearing meets pressure plate.
Pict5 Bottom of transmission looking up into a cut out. I thought in the past I could see friction material looking from this view, but the engine was out and can't be sure this was the right hole.

Is there anything to see here? I could get a better picture of the little access view hole on the bottom of the trans upwards. (repeat pict 5).

Phil



http://forums.pelicanparts.com/uploa...1679532966.JPG
http://forums.pelicanparts.com/uploa...1679532966.JPG
http://forums.pelicanparts.com/uploa...1679532966.JPG
http://forums.pelicanparts.com/uploa...1679532966.JPG
http://forums.pelicanparts.com/uploa...1679532966.JPG

Here are some pics of the area, note the clutch cable is disconnected, there should be 1.2mm (.047 inch) gap.

When I first went underneath the expected gap was there and it was correct with and without the cable attached. Then the clutch was pushed in and the gap is gone and won't come back.

Please have a look at the pictures below, is the omega spring okay? Anything seem out of place?

How does a worn clutch cause this? and why did the gap change during the examination?

Before I empty out my brand new 110$ of new oil and new trans fluid and do all this work... I'd like to know how this can happen..

Phil

http://forums.pelicanparts.com/uploa...1679537057.JPG
http://forums.pelicanparts.com/uploa...1679537057.JPG

I agree with clutch disc as the likely culprit. You might need to pull the clutch cover off as it's likely stuck between the big belleville spring and the clutch disc.

You can save the oil by cleaning out your drain pan really well, then draining, then tranfilling into a suitable container (old washer fluid jug or coolant jug). You don't need to waste the new fluid.

When you run out of gap, the disc is toast. Generally. Is the top of the pivot pin on the long arm for the omega spring being stopped by the L shaped metal tab on the aluminum bracket on the side cover? If not, that could explain the no gap issue.

Thanks guys.

John, here is a picture of the L shaped metal tab you are referring to, correct?
Is it in the right position? It's not touching any part of the tab, but, nor is it near the stop. Should A be closer to B with clutch cable not connected?

Please see picture:
Phil


http://forums.pelicanparts.com/uploa...1679585846.JPG

Should be right up against it with the long arm popped back. Take the short arm off, allow the long arm to rest at the stop, them put the short arm on, and adjust your clearance. The long arm needs to move freely on the shaft, not rusted in place.

Removed the levers. Zero rust, the top arm just swooshed out onto the floor.
Did nothing than clean omega.
Re-installed with omega locked at tab of L arm.
Little arm remained at original index (marked relationship to splined shaft).
Adjustment screw is almost fully protruding (screwed in nearly all the way), that's different, last time in was on the short side protruding...
1.2mm, 1mm, 25mm all achieved. Clutch goes in out nice.
Can't drive, wet with salt out.

What happened? Is my friction material nearing the end and didn't trip over the omega spring?
Secondly, before this event, I'd lubed up the creaking spring in the pedal cluster?

I should have tripped over the omega spring before removal, lucky to have not damaged anything on removal.


Thanks for helping me gain a little understanding of this system... Hopefully not just briefly delaying the eventual. I'd not experienced any clutch slip prior.
Phil

This was your problem.......
 

Phil,

You simply forgot to pre-load the Omega helper spring by pulling it rearward. The two (2) levers where out of positions when you made the 1-mm gap for the adjuster bolt.

Tony

Tony,

I don't know why I like this old car so much, it's like a good old fashion piece of chewing gum, just squishes right.

I still find it hard to believe that I didn't set up the lever arm correctly 20k miles ago, I've adjusted the gap several times since, it's never really changed. But it seems the most likely explanation? Don't know. Hopefully it works okay, it's ready to go for a drive.

Thank you all.

Phil


Edit:
I remember how this came about, It's what was inherited from the previous owner's garage. After changing headstuds I returned the clutch setup as found without much thinking, it was working well and I didn't change the clutch.

Seems to drive okay.

Now where is the cyl 6 oil leak coming from... Rocker bore leak check, valve adjust while there again..