Bad knocking under feet

[ratty dart 340]

Can you post a video with some GOOD audio?

Well.. Its been quite a few months. Much headway has been done to the car. We fixed the starting issue with a new ignition switch. Also fixed most of the wiring, and she idles flawlessly.
However, I think this dart has a curse(joking but not really). It seems once we fix am issue, another very complex issue pops up. I'm aware this is common with old cars, being that I had to replace everything on my engine in my 1970 toyota fj40.

The dart however, is something else. The bad knocking underneath my feet went away, didn't even change anything, but now the car doesn't stall when pressing the brake. All i did was unplug the main vacuum line to the brake booster, then plugged it back in. That fixed that problem somehow, but now another problem has emerged. The rear end has a clunk, and the rear wheels shudder upon takeoff.

From the car not starting when the door is closed, to seemingly magically "fixing issues", to creating another complex problem is very odd. This thing has taken me on a wild goose chase with goofy problems.

And that's where we sit currently.

 

[ratty dart 340]

Well.. Its been quite a few months. Much headway has been done to the car. We fixed the starting issue with a new ignition switch. Also fixed most of the wiring, and she idles flawlessly.
However, I think this dart has a curse(joking but not really). It seems once we fix am issue, another very complex issue pops up. I'm aware this is common with old cars, being that I had to replace everything on my engine in my 1970 toyota fj40.

The dart however, is something else. The bad knocking underneath my feet went away, didn't even change anything, but now the car doesn't stall when pressing the brake. All i did was unplug the main vacuum line to the brake booster, then plugged it back in. That fixed that problem somehow, but now another problem has emerged. The rear end has a clunk, and the rear wheels shudder upon takeoff.

From the car not starting when the door is closed, to seemingly magically "fixing issues", to creating another complex problem is very odd. This thing has taken me on a wild goose chase with goofy problems.

And that's where we sit currently

The clunk in the rear end could be u joints, driveshaft, axel bearings, but it seems pretty severe, so I think it’s something really bad in the pumpkin. This weekend I will be able to work on it so we will see what happens.

 

[Ironracer]

All BS aside, have Y'all Tried Praying over 'er? Prayer Works! Even if it don't fix the car, Maybe it'll show You things that you can use to make it work? Yes, I sound Crazy.......

 

[RedFish]

The clunk in the rear end could be u joints, driveshaft, axel bearings, but it seems pretty severe, so I think it’s something really bad in the pumpkin. This weekend I will be able to work on it so we will see what happens.

I'm going to place my bet on the U joint. Good luck with it

 

[Bad Sport]

so I think it’s something really bad in the pumpkin

Is it a 7 1/4? I have had many over the years that would clunk bad going from drive to reverse, if your idle is a little high it gets worse, lol, I only had one fall apart and required changing.

But do check u joints, especially a bad front joint, that can make life interesting if it lets go while moving, back trans mount too.

 

[Ottmundr]

Hey everyone, I recently bought a 1973 dodge dart sport h code car from a yunkyard for 3k. She had been sitting for more than 20 years after the previous owner drag raced it. She has a ford 9 inch rearend that he had swapped into it, and he also swapped in a first year 360 for the 340. The engine runs amazing for the situation and does "drive." However, when we start driving around the neigherhood, there is a really bad knocking under out feet. Its definetly not coming from the engine, but maybe the torque converter and or flex plate is the problem? Somehow the tranny fluid was still in good shape after sitting so long but maybe the tranny is screwed up too. Its a 727 btw.


Also, when we press the brakes, the car wants to die. This seems vacuum related but i dont know.

Thanks, Andrew
View attachment 1715866648

Did you take the vise-grips off the drive shaft?

 

[ratty dart 340]

Is it a 7 1/4? I have had many over the years that would clunk bad going from drive to reverse, if your idle is a little high it gets worse, lol, I only had one fall apart and required changing.

But do check u joints, especially a bad front joint, that can make life interesting if it lets go while moving, back trans mount too.

It has a ford 9 inch with 4.11 gears. Previous owner installed it. So it seems like he could have hacked the driveshaft and or other things.

 

[ratty dart 340]

Did you take the vise-grips off the drive shaft?

No of course not. Gives the car character!!

 

[Uncle Bob]

I bought a Duster with a Ford 9" in it. WTF are people thinking. Anyway ...

I had a bad noise in mine after I swapped it for an 8-3/4. The first time I took it out I brought it straight back barely moving because I was convinced it was going to puke the driveshaft out of it. It took a little while to figure it out, but eventually I noticed the witness mark from where the driveshaft was hitting the exhaust. The exhaust was built too close to the driveshaft, and the different offsets between Ford and Mopar rear ends caused the driveshaft to hit the exhaust after I switched to the 8-3/4. It could be something similar in the OP's car.

 

[Uncle Bob]

It has a ford 9 inch with 4.11 gears. Previous owner installed it. So it seems like he could have hacked the driveshaft and or other things.

The Duster I just mentioned ^^ had a Versailles rear end under it and the driveshaft used was the perfect length for the 8-3/4 swap. So there's no reason to hack the driveshaft, just use a Mopar part.

Coincidentally, the 9" in my car also had 4.11 gears in it.

 

[ratty dart 340]

I bought a Duster with a Ford 9" in it. WTF are people thinking. Anyway ...

I had a bad noise in mine after I swapped it for an 8-3/4. The first time I took it out I brought it straight back barely moving because I was convinced it was going to puke the driveshaft out of it. It took a little while to figure it out, but eventually I noticed the witness mark from where the driveshaft was hitting the exhaust. The exhaust was built too close to the driveshaft, and the different offsets between Ford and Mopar rear ends caused the driveshaft to hit the exhaust after I switched to the 8-3/4. It could be something similar in the OP's car.

Very interesting. Did yours have stock manifolds? Mine has completely stock exhaust, so what you said sure makes a lot of sense.

 

[Uncle Bob]

Very interesting. Did yours have stock manifolds? Mine has completely stock exhaust, so what you said sure makes a lot of sense.

Mine had long tube headers with the exhaust crowding around the drive shaft. Luckily I was able to loosen the reducer and the hanger then twist it out of the way to fix it.