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TR4/4A TR4A Transmission noise mystery

  • Thread starter Deleted member 12470
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Deleted member 12470

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Hi BCFers --

I am new to the forum and would appreciate some help.

While rounding a corner fairly aggressively last week, I heard a distinct "thunk" from under the car. I immediately slowed and pulled over but when I disengaged the clutch to stop, there was more clunking, this time in a regular rhythm.

I carefully shifted into 1st and released the clutch and everything seemed okay; but when I operated the clutch to shift the clunking started again. It stopped while going through neutral but again clunked briefly before I released the clutch pedal again in 2nd. Same thing into 3rd and 4th, although the clunking sped up as the gearing increased. The car otherwise drives normally.

The noise does not occur when in neutral or when the clutch is engaged. Engaging the overdrive makes no difference. There is nothing visually wrong under the car. The driveshaft U-joints look and feel tight; the transmission oil level is good and the clutch is adjusted properly. I have a recording of the noise, which I could not figure out how to attach to this post but would be happy to email. I would be grateful for any suggestions.

Dave Twyver
TR4_EH
 
sounds like its time to drop the transmission and check the clutch. if its a IRS could be the rear diff mounts. Internal transmission problems?

Hondo
 
A couple of thoughts,
The last time I had a similar clunk noise occurred when accelerating from stop..never while running or while I shifted and accelerated slow. The problem was the right rear IRS u joint, not really visible with the bootie on. Another hint to my problem was a mechanical noise/metal rubbing when I push hard down on the rear fender.
And my last transmission noise, and the second in many years was bad bearings on the transmission countershat and gear, items 54 and 56 in the Moss catalog. I replaced them with the new three bearing uprated design. Not cheap.
Just some thoughts. Robert
 
Broken rear transmission mount or engine mounts may be allowing the U-Joint to rub against the tunnel causing the clunking sound.
 
Thanks guys --

I did discover a bad u-joint on the RR axle but that is a different problem. All engine and transmission mounts are okay. I removed the carpets and tunnel cover and the clunking is definitely coming from the transmission. I can now hear it also in neutral with the clutch engaged, albeit not as loud.

It doesn't sound BAD but certainly not good. As Hondo suggested it is probably time to pull the transmission and look at internals...
 
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