Please forgive however convoluted this may seem: I have a 1964 Plymouth Belvedere with '3-on-the-tree' transmission. A little over a month ago I noticed a knocking sound whenever I depressed the clutch while I was in 1st gear. If I am coasting in 1st gear it knocks just a little bit. The knocking is related to something turning because it is a turning knock, if you know what I mean. I took my car to a local mechanic who told me that I needed a new transmission so I found an old used one that fit my specs: slant 6 .225 with 3 on the tree, in a junk yard. The junk yard owner noticed that my old transmission still had a sealed lid on it--which he thought was weird that the mechanic told me it was a transmission problem without even opening the transmission to inspect it. Anyway, he opened the one I bought to make sure there was no obvious problems and noticed that there was a broken tooth on on one of the gears--so he swaped out the broken part with a good part from mine and said well at least when you put this back on you will know whether or not it's your transmission or not. he also offered me a money back garantee no question. well, i took the new-used transmission back to my mechanic, he put it on, called me and told me that the throw out bearing was bad on my clutch and the whole clutch needed to be replaced. i went by to inspect the old throw out bearin and it looked shot so i gave them the go ahead. when they finally told me the car was done, they said there was still a knocking but that she was running fine. Sure enought there was a knocking, the same one that was there when i went in the first time!!!! and they are acting like it's fixed. needless to say i'm flustered. i waited for a month to get my car back, charged up the ass for a new transmission which i'm not sure i even needed to replace, and i'm out of cash and at the end of my rope. they are telling me i need a good used transmission if i really want the knocking top go away. does anybody have any idea what my problem could be???

Is your shift linkage adjusted so that the gears in first/reverse just start to engage even in neutral?

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Yeah....Im the one who destroyed this rare, vintage automobile.....

i'm not sure how to check. never ever had a problem like this before. do you recommend i take it back and ask them to check?

"does anybody have any idea what my problem could be???"

Just a guess, but I'd say your main problem is in your choice of mechanics.

Beyond that, it sounds like classic symptoms of a bad u-joint, probably the front. They cost $10 to $25, but total cost depends on which mechanic you choose. Lots cheaper if you do it yourself.

I agree! Jimmy T, you almost certainly did not need a new transmission. You may well have needed a new clutch and clutch-release ("throw-out") bearing. This is the danger in saying "OK, do it, here's my credit card" to a mechanic who is not both honest and specifically familiar with old cars in general and old Mopars in particular. The service industry today is set up to handle your '98 Toyota Camry or your '01 VW Golf or your '95 Buick Regal...not your '64 Plymouth.
I'm not quite clear on whether the knocking noise is related to the engine speed or the car speed. If it's related to the car speed, then I agree, both U-joints would be a prime candidate for close inspection.
Oops, no, not on a '64, which has the ball-and-trunnion type front U-joint. Rebuild kits are available for these, but their purchase and installation costs more than $10 to $25. If the front U-joint is badly enough worn to require rebuilding, then conversion to the cross-and-roller type front joint becomes worth looking at from an economic standpoint.

Another symptom of a bad front ball-and-trunnion front U-joint is whole-car shuddering on acceleration.

"Knocking when depressing the clutch in 1st gear" is an interestingly specific symptom. What if you shift to 2nd and depress the clutch? What if you shift to 3rd? To Reverse?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Are we talking about depressing the clutch while moving or sitting still? If sitting still, and the noise occurs, when depressing the clutch, that eliminates the trans and anything behind it. When the clutch is depressed, while sitting still, in gear, nothing in the trans is moving. Normally I would go with a bad Clutch pressure plate, or TO bearing, but these have already been replaced. Crankshaft end play can also cause a knocking sound, but that is usually worse with the clutch released. When the clutch is depressed, the spring pressure pushes the crank forward, and eliminates the knocking sound, of the crank moving back and forth.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

Well...maybe! Remember, we're dealing with a dishonest, ignorant and incompetent "mechanic" here, so who knows *what* has actually been done, and what's just been charged for.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks for the correction on the ball and trunion, and that may be a further indication of the actual problem! I've been a Mopar freak for MANY years, but I completely missed the B&T joint as a possible problem. That's because I've never worked on one and can't remember a Mopar I owned that had one. So what part of this car is the most likely for the questionable 'mechanic' to not understand? The Ball & Trunion joint! Makes more sense to me as the possible culprit now....

JimmieDart

The B&T joint is easy to check, get under there and look for a torn grease boot, a "dry" joint and wigggle the front of the drive shaft. Any side to side movement out of the B&T is a problem.
DD