Clutch noise - release bearing issue?

I have a strange noise from the clutch when the engine runs, the clutch is untouched and the gearbox is in neutral (ie while waiting for a traffic light).

Now I have the engine out (see this still video clip how I did it) I was checking the clutch.

What I found was that the clutch release bearing needs some force to move in the fork (difficult to explain).

Anyone having experience with this, is this is normal, what I could have done installing it wrong? Are different forks/release bearings combinations out there? Please help me.

Regards,
Hedde

With the return spring taken off the clutch actuating lever on the bell housing, there should be no effort to wiggle the lever, (first back and forth) and then take up the free play so that the release bearing is touching the clutch diaphragm.
Can you explain what motion you are doing that require force? There may be (say) a 1/4 inch or so free motion of the release lever before it contacts the clutch diaphragm and thus will not move (as it takes a lot of force to disengage the clutch.

Maybe you could send us photos of what the problem is with pasted in arrows showing the points you want to make

Dennis 69 OTS

Hi Dennis,

Thanks for your reaction. The fork or lever is moving freely, without any force needed.

The clutch release bearing does not turn free in the fork/lever.


(thanks Chris for the picture)

I see the pivot shaft sliding out to the left.
Is that intentional?

The release bearing should not rotate in any way. It is graphite and pressed in

It has to rotate slightly in the fork cradle ends because it swings in an arc. Hard to imagine it binding up that badly though.

Are you sure this noise is from the clutch? Many of us (myself included) get a buzzy rattle from the reverse idler gear in the gearbox when idling at a traffic light with the clutch pedal not depressed. It goes away as you depress the clutch, and isn’t apparent when driving in gear. Could that be what you are hearing?

Erica,
Correct. I thought maybe the bearing will not turn until it is free but I don’t see any wear on one side.
Thanks,
Hedde

Hi David,
I am not sure it the clutch. Is it possible to determine if it is the reverse idler gear and is it repairable?
Regards
Hedde

The ends might require a small amount of grease, not sure. I was wondering the same thing as mine was being assembled last week.

Hello Hedde,
The noise that David is referring to is very distinctive and very recognizable by those that have heard it before. It sounds rather like and can be confused with, by the uninitiated, a bad ball bearing race. You can get a good idea if its the Reverse Idler Gear using a mechanic’s stethoscope to find if the noise is emanating from the Right Rear corner of the Gearbox.

The ultimate test is with the Gearbox stripped and with the Lay Shaft Cluster and First Motion Shaft reinstalled (the Reverse Idler Gear still in place). Drive the First Motion Shaft with a Hand Drill, taking care not to damage the First Motion Shaft journal that engages with the Flywheel Centre Bush; I use a short piece of hose clamped to the First Motion Shaft and drive it via a short piece of steel rod clamped in the other end of the hose.

Spinning the First Motion Shaft and therefore, driving the Lay Cluster simulates the clutch being engaged and with the Main Shaft removed, noise from the other gears in mesh with the Lay Cluster is eliminated. Because there is no Reverse Gear in the Gearbox at this point, the Reverse Idler Gear can be freely moved to the rear, where it would be when engaged with Reverse Gear, and to the front, where it resides when Neutral, or a Forward Gear is selected, whilst the Lay Cluster is spinning.

If the Reverse Idler Gear is the issue, you will hear a distinct change of sound when the Reverse Idler Gear is moved from the Front (Neutral - Forward Gear position) to the Rear where it is when engaged with Reverse Gear. If the problem is not with the Lay Gear Cluster, the noise will disappear when the Reverse Idler Gear is moved to the Reverse Gear position and reoccur when moved back to the Neutral/Forward Gear position.

Invariably, when the Reverse Gear is examined, you will have to look hard to see slight wear on the area of the Gear that would engage with the Reverse Gear. At first glance you would think that there is nothing wrong with the Gear. When the Revers Idler Gear is in the Neutral position, its the rear section of the Gear that engages with Reverse Gear that meshes with the Lay Cluster Gear.

The only practical way to rectify this fault is by replacing the Reverse Idler Gear. Practically every Gearbox I refurbish has noise being caused by the Reverse Idler Gear and as this Gear in new form has been rather hard to locate, I now manufacture my own.

Regards,

Bill

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Hi Bill,

Thanks for this perfect explaination.

I wished I have asked this question when the engine was still in the car. Testing is now impossible, disassembly of the gearbox is beyond my mechanical skills. Catch 22.

Is the reverse idler gear problem a problem or an inconvenience. (Does it do any harm in the near future.)

Regards,

Hedde

Hello Hedde,
You can test for this issue with the engine and gearbox out of the car. If the Gearbox is separated from the engine, put the Gearbox into Neutral and spin it up as described in my previous Post. If you can hear what sound like a bad bearing rumble, try and identify if its coming from the Lower, Rear, Right corner of the Gearbox. In the absence of a stethoscope, a screw driver with handle held to ear and blade end touching the area of interest may do. Don’t try and select Reverse (or any other Gear) with the First Motion Shaft being driven when the Gearbox is fully assembled.

With regards to further damage, in theory yes, as you have a slightly damaged Gear Form meshing with the gear on the Lay Cluster that also meshes with First Gear on the Main Shaft. In practice, it seems not, or it will take a long time for damage to these other gears to occur. For me, I can’t stand the sound and it is still there when the car is in motion in any Forward Gear; its just a little harder to hear over the road and other Gear noise. Accordingly, I would fix it.

Regards,

Bill

1 Like

Bill,
Thanks again. I separated the gearbox and engine yesterday evening. I will try this soon.
Regards,
Hedde

Here’s the set-up I used (TR box, not Jaguar). It’s a motor from a Maytag connected to the First Motion shaft with a hose as Bill described:

Maytag

Custom shifter too though, as noted, no shifting while running.

2 Likes

From afar in distance and time. I’ve not messed with a clutch for a very long time… well, yeah, my forties Hot Rod… The project that preceded the SIII.

With the engine running and the transmission in neutral, o you hear the noise from down under?

If so, just touch the clutch pedal lightly, just enough to take up the slack., Noise goes away?

If yes, it is a “bad” throw out bearing.

Caveat, I’ve never messed with the “odd to me” carbon variety. Only a more conventional bearing,

Carl

Bill,
I did the test yesterday with a electric screwdriver. I would say the sound comes from the left front side (the front for me is te side of the input shaft).
For sure the sound is from the gearbox, not the clutch I thought at first.
Regards,
Hedde

I cleaned everything up and now the bearing is moving smoother in the fork. I was afraid the inside of the bearing would touch the shaft but I think the movement of the fork once installed in the car is not that great that this will happen. (Out of the car is is happening.)

Unless the fork is bent in some way it shouldn’t collide in the normal range of operation. The arc it moves through is pretty subtle and so long as the bearing is held parallel to the clutch, the hole in the center is large enough to accommodate the shaft.