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TR4/4A Mysterious TR4A tranny noise [that vanished] -help

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Adrio

Jedi Knight
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I have a mystery with the transmission on my TR4A. I have just finished a complete frame off restoration on the car and have driven it about 700 miles since then. Today my wife and I were touring with it and after downshifting and turning a corner (not a hard down shift), the tranny started to make a terrible noise. I stopped the car and the noise continued but was definetly tied to engine RPM. This noise stayed even wen in neutral. While driving the noise was heard in all four gears. If I stopped the noise would continue with the clutch in or out. BUT if, while stopped I put the car into gear (with the clutch in of course) the noise would stop.

For what it sounded like. Hard to describe with workds but I will try. It was a clicking type sound. Maybe a better way to describe it is a metalic version of the old playing card held on to your bike fork with a clothes pin and rubbing against the spokes from when we were kids. But again like that but as if all the parts were metal and more subtantial in mass.

The mystery is that as I tried top figure it out. I was drving slow and listening for changes in sound and such depending on gear and speed and such, the sound stopped. I drove home about 10 miles and nothing came back (I know it was a bit dumb to drive it home). Looking under the car there is no sign of anything loose. The car seems to be driving fine now.

Does anyone have an idea what this is. I am worried I will have to tear down a lot of car and maybe not be able to find what it was.

Thanks in advance.
 
Hi Adrio,

You might drain the gearbox and look for any metal particles in the oil (I hope you don't find any).

Also remove the bellhousing/clutch shield from the bottom and look around in there with a flashlight and small mirror, for anything broken or out of place, anything lying in the bottom of the bellhousing.

Based on your description, the suspects are driven parts that are in motion all the time, whether in gear or not, whether the car is moving or not. It's also rpm related.

That narrows it down a lot and rules out the starter, the drive shaft, speedo cable & connections, differetial, axles, etc., and all but the input side of the gearbbox.

You said a recent restoration, but can you elaborate what was done in and around the gearbox?

I agree it might be a bad throwout bearing.

Inside the gearbox, some layshaft are known to be a problem, insufficiently hardened. Also it might be part of a synchro mechanism. However, a single gear tooth, or any other gearbox part, or even something inadvertently left inside during a rebuild, that finds it's way into the wrong place in a gearbox might cause the noises you describe. Eventually it finds it moves and the noise stops.

Hope it's just a minor problem.

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L
 
Re: Mysterious TR4A tranny noise [that vanished] -

Thanks for the tip, Peter and Alan. In answer to your question about what was rebuilt (you can look at my website for more details and pictures), the tranny was not touched inside and as far as I could tell it had not been opened by the previous owner, but I replaced the throwout bearing with a new one, I also replaced the clutch with a new one (both the clutch and pressure plate, as a kit). On the engine side it has all new bearings and rings, cylinders were honed, head was machined and hardened valve guides installed. On the drive line, all new U-joints and bearings.

I will take a peek in the bell housing as you suggest. In the mean time keep the ideas coming, as this one has me stummped.
 
UPDATE Mysterious TR4A tranny noise

Well folks, I bit the bullet and drained and removed the tranny from the TR4. The oil told a big tale. First it was SILVER in colour not gold or black. The sad part was the silver was from distroyed needle bearings. In the oil I also found about a dozen or more pieces of neelde bearings (about 1/16" in diameter). So the tranny will have to be taken down and fixed.

I may see about just installing my spare gear box though as one option. Or as a second option, if these needle bearings are from the output side of the gear box (any one have any ideas where they live in the box please let me know). I may try and merge this box with the TR3 overdrive box I have to give me an O/D TR4 box.

I will keep you informed. I may post some pictures of what I found on my web site this weekend.
 
Re: UPDATE Mysterious TR4A tranny noise

Hi Adrio,

[ QUOTE ]
The (gearbox) oil told a big tale. First it was SILVER in colour not gold or black. The sad part was the silver was from distroyed needle bearings. In the oil I also found about a dozen or more pieces of neelde bearings

[/ QUOTE ]

Ouch! I'm really sorry to hear that.

I think it's a pretty sure sign that the layshaft is bad. The needle bearings run on it, fitted inside the laygear. There have been some low quality layshafts sold in recent years, with insufficient surface hardening. The rollers running on these shafts rather quickly break through the surface, then disintegrate into large and small particles you are finding.

The fine silvery stuff in the oil is likely the surface of the shaft itself. All those particles can damage or heavily wear other areas within the gearbox, too. If an OD had been attached to the box, it would almost certainly need a complete rebuild now, too.

You might check with Quantum Mechanics about a rebuild. TRF's rebuilt boxes seem pretty good, too, but only to stock configuration. QM offers some opportunities to upgrade in several places for a stronger g'box, overall (i.e., additional roller bearings on the layshaft, roller-type thrust bearings ala Stag g'box, and a few other strengthening improvements).

[ QUOTE ]
I may try and merge this box with the TR3 overdrive box I have to give me an O/D TR4 box.

[/ QUOTE ]

There are enough differences between the TR3 gearbox, the early TR4 4-synchro box and your TR4A 4-synchro g'box that I think you'd just be inviting *lots* of problems trying to fit parts from one into the other. Problems = dollars.

Some of the issues you'll find are: subtly different gearsets used throughout the development of the TR models, longer and shorter input shafts, different clutch splines, a steady series of improved internal & external components over the years, 1st gear synchro and more. Parts from a 3-synchro box are almost certain to be incompatible with parts from a 4-syncrho box.

I'd strongly recommend instead either rebuilding/converting the TR4A box you've got or picking up another TR4A through TR6 gearbox, even if it needs a rebuild and conversion to overdrive. A Stag or 2000 box is a possibility, too, and might already come with some of the upgrades mentioned above. Later TR6/Stag/2000 boxes, if OD compatible already, would be set up for J-type OD. Some folks prefer the J-type over the A-type, which was used in a couple different versions on TR2 through early TR6.

John Esposito at Quantum Mechanics can retro-fit most TR gearboxes to OD specification.

As a general rule, the later the gearbox and OD, the easier and less expensive it will be to repair or modify. This is because parts are more widely available for the later configurations. Some parts for the earlier g'boxes and ODs are next to impossible to find.

[ QUOTE ]
I will keep you informed.

[/ QUOTE ]

Please do!

Again, sorry to hear it wasn't a simple thing like a clutch fork pin!

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L
 
UPDATE No. 2 Mysterious TR4A tranny noise

I ended up removing the bad tranny and installing my spare TR4 tranny in the car. It turns out the tranny that died was from a TR6 and not a TR4. I noticed some slight differences when I had the two side by side and did a bit of investigating.

The job was a bit more work then I thought only because of a few "issues" Like the clutch fork was missing on the replacement tranny so I had to swap that out. The TR4 tranny is a bit shorter (1/2") and so I had to move the rear mount, which meant I had to remove the exhaust to get to a nut. The shift lever was rusty so I had to try and swap that but could not get it out due to other rust. And there weere no people on the street to help me put it back in, so I had to wait for a helper.

I am going to start an other thread on this "new" tranny since it has raised a question in my mind so please go look for it as it is a perplexing one (for me at least)
 
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