The sound comes from the transmission only under 2 circumstances...
1. If the brake lever is pulled all the way back.
2. If the car is stopped on a slight incline such that the weight of the car slides back as the foot break is held.
Not a knocking but a whirring, groaning sound, especially at low RPM.
What is it?
If it's the noise I'm thinking off, pretty much every T transmission makes that noise, especially if your transmission is a little tired. That's just the sound of the straight-cut triple gears. Even the best rebuilt transmission will still have some of that whirring sound.
Now if it's extremely loud, then you may have a problem. Also check for bands that have been adjusted too tight. They can make the transmission noisier if they are dragging.
This trans is tired, I am just trying to understand why it makes this sound under these specific circumstances. Is there a clearance problem somewhere?
Just think about your old car as an old (+90 years)lady. As you will making the lady work she will be whirring and groaning, she even can die and you will need to have and treat her with respect for her age.
With your car it is just the same, treat it with respect and there will be less noise.
Keep in mind. There was and will be always noise coming out the transmission for the reasons Cameron explained.
Have a fine day
My wife's makes a noise when you are sitting still with the brake applied, but not when sitting still and the brake not applied. My TT used to do that with the old engine and tranny. That is weird because at rest, the brake drum is not turning, so why does tightening a band up around a stationary drum make a noise? I think it is the brake band pulling the drum into a slightly different position than it normally rides in, resulting in either the gears running in a slightly different place or just a little load on the bushing that it doesn't see without the band tight. I'm not going to worry about it.
When the brake lever is pulled all the way back none of the bands are engaged. The brake drum is stationary but has no band tightened around it.
This is probably not your problem but just in case here goes. When installing the driven gear on the brake drum shaft, the book calls for 6 thou clearance. If you get it too close, you can get an intermittent grinding sound when the engine is warmed up. Its due to the rear surface of the driven gear touching the end of the low speed gear shaft as things expand. Easy enough remedy, increase the clearance.
Why, when talking about noise in a transmission no ever mention the flange on the triple gear bushing? In forty years of working on transmissions I have yet to find a transmission triple gear that didn't have the bushing flange completely gone. This allows the triple gear to RUB DIRECTILY ON THE FLY WHEEL. The next time you take a transmission apart take a straight edge and place in across the flange end of the gear. You will soon see the the flange is worn. Take a look at your fly wheel and you will see a shiny worn spot the size of your triple gears. Can yu imagine how much power you are loosing in Low and reverse.
I was referring to the foot brake in the case of my TT and wife's Touring.
Dave, that may be what is making the sound I am talking about. Most likely theory I've heard yet.
I thought that Hal was telling us that his wife made a noise when he was sitting still - on the couch instead of mowing the lawn.
I am happy that got straightened out
Well.......she does make noise when the lawn needs mowing.....and when the driveway needs grading.......and