Gear grinding... 69 SII FHC

I’ve owned my car for close to a year. I’ve had several parts replaced as the car had been sitting (the usual suspects - radiator, cooling fans, starter, fuel pump, tach, slave cylinder, convert to electronic ignition, etc). Body, suspension and interior in great shape.

Now that you know a brief history of my car, my issue is with the gear grinding. Unfortunately I have no history on any engine or transmission work performed. : / It could be my imagination, but there is no grinding if I am deliberate with gear shifts UNTIL I’ve driven say 40 miles or so, then it acts up. Did so today, I was afraid I wasn’t going to get home. Was sticking trying to get into 1st gear badly. Once in first, the rest of the shifts were ok with the exception of reverse. That too was a bear, I could’ve ground a quarter pounder… I read the thread on gear shift issues and the shortened shaft issue (no jokes here), throw out bearing, synchros, etc. and just got confused (and scared)… Any recommendations?

If it wont go into reverse, the most likely issue is inside the bel housing…, ensure full throw of the throwout fork.

If that’s correct… the next step is not pretty.

Ok pretend I’m a mechanical moron (which is true). If you have medical questions, I can help…what is a “full throw of the throwout fork” The next step is a full rebuild I am guessing? What does that exactly mean? (use small words…). What am I looking at price wise dare I ask?

This is asking you to check if the arm that disappears into the bell housing is getting full travel and dis-engaging the clutch pressure plate.
If it is moving as far as it can and you are still experiencing the grinding then it means you are likely to be removing the engine and gearbox for a full strip down and recon. Price will vary with where you are living.

Feel lucky?

The first thing I would do is a good bleed of the clutch hydraulics.

Maybe no help but you don’t have anything to lose by trying.

Ah! Got it. Thank you!

Yes, figured that would be the first thing to try. Thank you.

You say the slave cylinder has been replaced. If it was the clutch slave then your problem is most likely either the thing needs to be bled, as already mentioned, and or the actuating rod needs checking/adjusting. Both are easy to do but the car needs to be clear of the ground high enough for you to get under it. Check the manual for the correct adjustment and procedure for your car.

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Today I checked with my Jaguar repair guys who did all the work on my car when I acquired it. I brought up the fact that the car is reasonably ok deliberate shifting UNTIL I get to about 40+ total miles during an outing. It’s at that point that the shifting becomes increasingly difficult. Their opinion is that due to the likely worn clutch, synchros, etc. as the car warms up and trans fluid thins out, smooth shifting becomes increasingly difficult. I may consider an overhaul of the transmission since I don’t know the history. I expect I’d be looking at $4K.

You could try some 140 weight gear oil. It takes a little less than 2 quarts. This assumes you’ll never drive it in cold weather. If it’s still unacceptable you could always rebuild it.

How many recorded miles on the car ?

Heck, I only drive in cool & cold weather (35-65), warmer than that and the cabin is too hot for my liking. Summer temps here of 85-90+ are way too hot for me. I don’t even put the top down on my little Figaro when it’s goes above 80!

It had 100K when I purchased it. I rolled it over.

That makes no sense to me. In the original post you reported that once you got going the shifts were fine and that the problem was shifting into first or reverse. That does not indicate worn synchros to me, in particular the part about thin oil as it warms causing it. As others have stated you should confirm that the clutch system is set up and working correctly before you consider a multi thousand dollar transmission removal, rebuild and install.

Salvi, sorry to hear about your problem. The temperature issue makes what should be straight forward confusing, IMO. I am not of the belief your problem is inside the transmission. Reverse has no syncro, and it grinds very hard going in to reverse. You did not say, but maybe you can check- after the problem starts, if you go into reverse (which will stop the gears) go back to neutral, and then try reverse again, keeping the clutch pedal down, does it grind again? I believe it will. If so, this clearly tells me the clutch is dragging. Which is what most here are saying, so some of what I will say is repeating others. Why dragging only when hot? Some thoughts:

  1. To agree with others, clutch hydraulics. As it warms up and is used, the clutch master cylinder seals leak and you do not get full stroke. Usually the system seals better when hot, but not always. I would think if this were the problem, you would feel it in the pedal. But it sure beats pulling the transmission. Of course, be sure it is adjusted properly.
  2. Pressure plate is falling apart. Broken springs, etc. moving around in there jamming the clutch disk. apparently can get worse with heat as the clutch disk gets hot and expands.
  3. Oil on the clutch disk. I understand sometimes as the oil gets hot, it will tend to make the disk stick to one the flywheel or pressure plate, something about the spinning sucking it tight???
  4. The clutch disk is sticking to the splined shaft. Car not used a lot. Splines rust and get dirty. One would think it would loosen up as it is used, but has heat expands the shaft possibly faster than the disk hub, it sticks more. Actually- this is my guess to your problem. If you have a really lucky day, and you have the rear bell housing inspection hole, maybe you could spray some penetrating oil and lube on the disk hub and spline.
  5. Broken/flexing throw out bearing mechanism.
    I will be interested to learn what you find. I am certainly just guessing. Good luck.
    Tom

Sorry if there was confusion. The gears are fine in the beginning of drives, bad by the end if I’ve been out for 40-50 miles.

Tom, thank you so much for the detailed input. I have another Jag specialist I have used, he no longer pulls engines but maybe he can review your input with me and give me a better understanding. I will also run your input across my primary Jag mechanic. I will try the reverse / neutral maneuver though it may be pointless as the problem has to this point only occurred with extended driving, of which I have no plans to undertake, as it’s scary as heck when you can’t move the stick in any direction…

Ok. This was the section from your first post that made me believe that your shifting on the go was normal.

Everything I’m hearing could be attributed to air in the hydraulics or a failing seal (e.g. the clutch slave) – two of the easiest things to check and fix.

One way to possibly rule them in or out is: when the problem occurs try rapidly pumping the clutch pedal and see if the gears can then be engaged.

Air will compress and rapid pumping may briefly restore better clutch action. Pumping may also overcome a weak seal in the slave.

When this happens you could pull over and stop, turn off the engine and place the car in neutral. Rock the car back and forth a few inches 'till you’ll find a spot where you can shift into all gears without using the clutch. If you can it’s probably not the gearbox …

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