I’ve been putting the miles on my car and have noticed the clutch engaging deeper and deeper into the pedal throw so I figure it’s time to adjust the slave. After removing the external spring (I have converted from the hydrostatic slave) I fully expected to find too much movement of the TO bearing arm (> 1/16") but actually found it to be pretty tight! What the heck? Obviously I don’t understand what’s going on here.
Isn’t it true that normal wear results in one having to adjust the excessive free play out of the TO bearing arm?
Also, may not matter but, the slave cylinder end seal was pushed off its seat. Is that pertinent or unusual?
No, as things wear, the free-play DECREASES. This is precisely why it is so critical to do the periodic adjustments. Once the free-play disappears, the throw-out bearing starts wearing VERY quickly, and the clutch can also start slipping.
Had to think about this one and have to agree with Ray.
When new the friction plate is nice and thick(ish) this causes the fingers of the clutch plate to be compresses moving them towards the engine. As the CP wears the fingers move away from the engine towards the throwout bearing, reducing the clearance.
Several J-L members coached me on this one when I had to extend the slave cylinder shaft after installing a new clutch and pressure plate. Got the concept but still wonder if there is a difference between the OEM pressure plates supplied back in the day and today’s. Something has to be different to require a longer shaft/bolt…
I think I am in the same boat but sitting behind Craig since my '68 slave cyl does not have external spring so I assume it is the hydrostatic type. I do not have any clutch problems yet but after reading some of the posts the last several months it sounds like something I need to get a better understanding about converting to and adjusting. Craig if you find something that explains things well can you pass the link about it on to me ? I will do the same but looks like you are already better informed than I am on the topic since you have already done the conversion.
I inserted my borescope to take a picture but ran out of time before I got the best angle. Will post a pic when I get a good one.
I was initially concerned that the “gap” between the TO bearing and the “release lever plate”(?) (is that the correct terminology?) was not symmetric. But, if I’m seeing George’s picture correctly, his isn’t either. That is a great relief to me.
I am beginning to suspect that the connecting rod is too short. After adjusting to spec (1/16"), I can no longer shift into gear without bad noises! May be that the piston in the slave isn’t retracted enough due to a short rod and this issue hasn’t presented itself until my first adjustment, maybe? Hopefully?
Anybody have a spec on the correct length for the connecting rod with the short slave cylinder?
It is very simple to fabricate a longer connecting rod out of a 5/16" bolt from any big box store, even if you have to cut the course threads off and cut new fine threads.
It may be unnecessary to do so if you simply pull the existing rod out and measure (thanks for the pic Benny) to determine whether you have the long rod or the short rod.
If you can’t move fluid through the system it’s highly likely that you have a bad clutch master cylinder.
and
During a total restoration and while building the hydraulic systems, be very wary of rebuild kits of unknown quality. You might get two years out of them, you might not.
Thanks all for your help.
Craig
p.s. Oh! and I think I’ve got it now about the wear and the free-play on the T.O. bearing.
Looks like you are trying to post videos to the forum. As far as I know, the only way to do this is to first upload the videos to a personal youtube account, and then include a link to the video in your post. When it comes to setting the free play, you need to push the pushrod and piston all the way into the cylinder first, and then measure how much play there is before the throw-out touches the pressure plate - see page E.7 of the Workshop Manual.
OK. Let’s try this again… I understand that as wear commences the freeplay will be reduced and you have to adjust for that to keep it at 1/16". This explains why you need a “longer” rod after you replace your clutch.
However, I don’t understand how the freeplay is to be measured. With the spring removed, I can compress the piston easily a good amount (even though I’ve bled my system thoroughly.) So, is the freeplay before or after the initial compression? Where is this “freeplay” supposed to occur? I photographed E.7 for reference.
The clutch feels OK when driving the car… other than the nearly 50% down-pedal travel before I feel much resistance. It seems to start biting just off the floor when letting off the pedal and engaging… not noticeably different that most any manual cars I’ve driven (new and old.)
If you get a second, please check out my videos. Please tell me what you think of my “freeplay” and how my “regular operation” looks.
Thanks for posting the videos which I can now see. You say that when connected, the spring will pull in the arm easily “that far”. Are you saying that it pulls the arm in as far as you can push the piston into the cyclinder? It is important that it does just that - the spring must pull the piston all the way back so that the release bearing is clear of the pressure plate to avoid premature wear. If the spring doesn’t pull it all the way back, you can tighten the spring by rotating the tab it attaches to at the front end to increase the preload.The free play that you show in the first video is, if anything, a bit more than 1/16". That isn’t a problem as long as you are still able to get the clutch to fully disengage when you press it - ie no gear grinding when changing into first or reverse. Just to confirm you have free play, try the following test: Put the spring back in place, and let it pull the piston/arm back. Operate the clutch a couple of times and release it so that it settles in it’s “normal” at rest position. Now, with the spring still in place, pull the push rod out of the cylinder until the release bearing hits the pressure plate. That is the “real” free play that you have. Was there any? Was it at least 1/16"? I hope this makes sense…
When I changed over my slave cylinder a few years ago I did not really measure anything. I just made sure the external spring would bottom out the rod into the cylinder and then set the free play to where my foot “liked it” and everything shifted normally. Then with the car not running I slid underneath with my phone camera and viewed that there was a visible gap between the carbon on the throw out bearing and plate on the clutch when looking through the inspection hole on the bottom of the bell housing. I check it occasionally to make sure the gap is still visible since my carbon layer is getting quite thin.
Andrew
Push the rod all the way into the cylinder with no spring attached.
Keep the rod fully pressed into the cyl.
Now adjust the rod so that you get 1/16 play.
Now re attach the spring.
However I do believe the master cyl is not letting all the fluid back, the pushrod in the master may need adjusting so that you get a small amount of play at the pedal.
Yes there are two amounts of free play, a small amount at the pedal, and a small amount at the slave.
Making a total of about 1 inch before the carbon starts pushing the diaphragm. pressure plate.
OK. I can try this, but here’s my problem. That spring is TIGHT. It’s all I can do to get that spring on the connecting bolt. I can do it with needlenosed pliers and a lot of patience, and then carefully pull out the pliers and the spring snaps into place, but it is TIGHT. I don’t think I can manually move the piston out of the cyllinder with the spring attached. Should it be that tight? I will also check the inspection hole this time.
Tight is good. It’s important that the spring pulls the mechanism all the way back into the cylinder. On my '63 I found that this was not the case - I suspect that a weaker/longer spring had been substituted, and as a result there was no free play, even though the push rod was properly adjusted. If you are sure that the spring is pulling it all the way back, and you have the free play in that position (as verified in your video with the spring removed), then you should be in good shape. The C5120 spring is the correct one.
The important thing…really the only thing…is to have a gap between the plate and release bearing when the clutch is disengaged. The sensible way to do this adjustment is to sight the gap through the inspection hole, and adjust accordingly. You can fine tune a bit if the pedal feel isn’t good. Freeplay isn’t as precise an adjustment as it’s made out to be: it’s a compromise between allowing enough of a gap for a season’s wear and clutch feel. Doing it by sight accounts for sixty years of wear and tear and an accumulation of questionable replacement parts.
