Help with 1970 OTS Transmission PLUGS?

LIfted the car today and noticed that two openings and it looks like I can see the flywheel on the forward one and some other gears in the other. Attached is a picture. I would assume a plug goes in both. Are these holes open or do they have a plug?

My '68 has a cover plate on the forward inspection hole that pivots side to side. Looks like I can see the remains of the attachment/pivot point in your photo. On mine the rear hole to view the clutch throw out bearing has no cover.

David
68 E-type FHC

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I see what you are talking about. I’m looking at the manual on page e.6 and it looks like you can see the flywheel also?

Yes I can see the flywheel teeth through my forward hole and the rear hole is where to check for some gap between the throwout bearing and pressure plate. Here is what my forward cover plate looks like and probably an example of why it is there.

David
68 E-type FHC

Yes, and if you get the flywheel in the right spot you can also see the engine number stamped on the edge:

The rearward opening is useful for examining the thickness of the TOB:

I use a dab of paint on it and take a photo every 5000 miles or so to track consumption.

The rotating cover is readily available from the usuals. The rearward opening was open but I use a length of Gorilla Tape over it just because you never know what might happen.

Alittle off topic but I’m under car to adjust clutch. Do I need to disconnect the knuckle joint to turn the operating rod into the knuckle. I loosened the locknut, but I can’t see how to screw the rod into the knuckle joint. What I’m I missing?

There are supposed to be two small flats on the rod that you can put a wrench on. Or turn it with a pair of pliers. If it doesn’t turn, pull the pin and remove the rod and free up the threads. Might require a tap down the female and a die over the male threads.

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And just in case you don’t know – there is nothing holding the rod in the slave. Once you undo the end with the pin and eye you can withdraw the rod - just don’t press the clutch pedal while everything is apart.

I’ve taken a light and shined in the rear hole and can’t see anything like this picture? I’m going back out to see if I’m just not seeing the right thing.

oh man - it’s way up there and I finally got it. The gap in mine might be alittle bigger than the gap in the picture you show. Is that OK?

Slightly bigger gap is fine if the clutch works well.

No gap is not good.

There is hardly any free play in the clutch pedal - is that because of the bigger gap? That is my goal - to get more free play in the clutch pedal.

Are you defining free play as the easy movement before the pedal really moves the pushrod… or the distance the pedal & pushrod move before the clutch disengages?

Something doesn’t sound quite right here, so I’m wondering if you have interpreted Geo’s photo correctly. Here is is with some additions:

The red line is the bearing surface of the pressure plate. The yellow line is the carbon ring of the Throwout Bearing (TOB). The Green Line is the cast iron body of the TOB that the carbon ring is mounted in, and the Blue Line is the clutch fork that pushes the TOB towards the pressure plate. The “gap” we are talking about is the thin black vertical line between the ends of the Red (Pressure Plate) and the Yellow (Carbon ring of the TOB).

The wider that gap is the more the TOB has to move before it meets the resistance of the pressure plate. This translates into a correspondingly larger free play in the clutch pedal before you start to feel resistance that indicates that you are operating the clutch. The movement of the clutch pedal, and the slave pushrod for that matter, can be thought of as having three phases:

  1. Free play - this is the initial amount you have to move the pedal or pushrod before the carbon TOB touches the surface of the pressure plate. During this phase the pedal offers little resistance as the only resistance comes from the pedal return spring, the master cylinder return spring, and the clutch slave return spring, all of which are pretty weak.

  2. Applying the clutch - during this phase pushing the pedal causes the push rod to push the fork to push the TOB against the pressure plate. The springs in the pressure plate are strong, so the resistance to movement is high. During this movement the pressure plate starts to unclamp the clutch driven plate.

  3. Clutch fully applied - the further you push the pedal, the more the pressure plate releases the clamping pressure on the driven plate. Eventually, the driven plate is free to move independently of the pressure plate and the clutch is fully released. If you have a diaphragm clutch, the geometry of the pressure plate may actually require less foot pressure to be required during the final stages of applying the clutch. Once the clutch is fully released, and additional pedal movement will make no difference, and at some point (before the pedal hits the bulkhead) the stops in the pressure plate will prevent any further movement.

A properly set up clutch will have a small amount of free play - enough to ensure the TOB is just clear of the pressure plate. If you have too much free play, the pedal will need to be pushed further before you start to apply any load to the pressure plate, and you run the risk of running out of pedal movement (ie the pedal hits the bulkhead) before you have fully applied the clutch. If that case it will not be possible to change gears cleanly, or even at all.

A quick note about “pedal free play”. The Service Manuals always talk about free play as measured at the slave cylinder pushrod, not at the pedal. There is a good reason for this. If there is any slop in the linkage from the pedal pad to the master cylinder pushrod, that “free play” does nothing to advance the slave cylinder. It is quite common for there to be up to 1" of pedal free play due to the wallowing out of the hole in the master cylinder pushrod fork by the clevis pin. This free play may deceive you into thinking you have free play at the clutch slave, and therefore at the TOB, when you have none. Sorry for the long-winded explanation…

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Steven,
The part number for that missing cover is C11910 per my copy of the Jaguar Series II E-Type Parts Catalogue. Most of the usual sources in the USA (Moss, SNG Barratt, Welsh Enterprises) carry it since it was used on a bunch of different model Jaguars.

Paul

Let me make sure my understanding of pedal free play. My clutch engages when the pedal is almost all the way away from the floor. So what I am saying is I have to let the clutch pedal almost all the way from the floor to engage. I thought free play was when the first push on the clutch pedal - free play is how far you need to push the pedal to disengage the clutch. Do I have this backward?

Paul,
I just ordered parts from Moss and I ordered the cover. Thanks

David,
After reading your post (carefully) I believe I was mistaken and I have to much free play. Let’s say I have my foot pressing the clutch pedal all the way to the floor. I would think the clutch should engage about half way. Mine engages almost all the way up.

That is incorrect. You are wrong on two counts. First of all, for the reason I stated at the end of my post, we don’t talk about pedal free play - it is a pretty meaningless concept in this context. We are talking about free play at the end of the slave cylinder push rod. Secondly, the free play at the slave cylinder pushrod is how far you have to push it to for the TOB to first touch the pressure plate, at which point you start to feel the spring resistance of the pressure plate. The clutch will take a significant amount of movement beyond this point before the pressure plate releases its grip on the driven plate and allows smooth gear changes.

Here’s an example to better understand what you are experiencing

Let’s start when you are stationary with your pedal pushed all the way to the floor and you have a gear selected (ie not in neutral). As you slowly lift your foot off the pedal at what point does the car start to move? I think you are saying that you have to lift your foot nearly all the way before the car starts to move. If this is the case, you probably have no free play at all. Even with the pedal fully released the TOB will be bearing on the pressure plate and causing excess wear.

Now look at it in the other direction. Start with the pedal fully released. When you put your foot on the pedal you should be able to push it some distance before you feel any significant resistance at all. During that light resistance phase you are just taking up the free play to get the TOB to touch the pressure plate. Then as you push further there should be a point at which the resistance instantly becomes much greater. Now you are pushing against the stiff resistance of the pressure plates springs. If there is no such point where the resistance changes dramatically, then you don’t have any free play.

If you have no free play, which from your description I believe to be the case, there is NO gap between the TOB and the pressure plate when the pedal is released. Take another look at the marked up photo I posted, and compare it with what you see. Ideally, take a photo of your own own and post it here and we should be able to nail this down.

You do have an external spring on the slave cylinder, don’t you?

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Green: Free Play

Yellow: Clutch Pressure Plate Operation

Red: Fully released

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