Vintage Car Thread - Discussion and Parts Requests

[jamespowers]

You have to use a make/model lol



Very helpful info! I just had an issue with vapor lock in the Dart the other day.

The station wagons. The Dart doesn't have vapor lock. It is just a Dart.

 

[AtomicEraTom]

I had a green one, and a blue one, still have a brown one.

The station wagons. The Dart doesn't have vapor lock. It is just a Dart.

It runs good, except when it's hot it gives a little trouble starting on occasion. Only when it's really hot, though.

 

[LizzieMaine]

Some guy who saw my car parked outside the theatre last night told me to try the Clothespin Trick for vapor lock -- just clip a few clothespins on the fuel line ahead of the carbeurator, so they'd work as heat sinks and keep the gas from boiling. So I've been driving around with clothespins in place, and it actually seems to work. It makes no sense at all -- the laws of physics tell us that wood is a poor conductor of heat and is therefore a lousy choice for a heat sink -- but I don't care if it's voodoo if it actually works. Amazing.

 

[Stanley Doble]

I have heard of that before and I can't explain it either. Just like I can't explain why a battery left on a cement floor will go dead. Lots of people have told me this is nonsense, I say leave a good battery on a cement floor for 3 weeks and see what happens.

 

[DeeDub]

It makes no sense at all -- the laws of physics tell us that wood is a poor conductor of heat and is therefore a lousy choice for a heat sink -- but I don't care if it's voodoo if it actually works. Amazing.

Could it be just the opposite? Wood is a good insulator, so perhaps it's keeping heat outside the lines from vaporizing the fuel.

 

[rjb1]

Wood isn't the best heat sink or conductor of heat, but it's not zero in that regard. And beyond being an inert heat sink, the "fins" composed of the two legs of the clothespin are good in getting rid of heat. (Consider the internal fins on the car's radiator or the fins on the heat sink inside your computer.)
An "upgraded" clothespin trick needed here in the South where it's hotter is to cut some small strips of aluminum foil about 1 x 2 inches and use the clothespins to attach those strips to the fuel line.
You get good thermal conductivity from the aluminum plus a good fin effect due to forced convection from the air moving around the engine.

 

[LizzieMaine]

If It Ain't One Thing...

If it ain't one thing it's another. Driving the Plodge home from work tonight I'm starting up after stopping at a stop sign and hear a loud CLUNK from somewhere behind me, and the car is immobilized right in the middle of the intersection. A couple of bystanders helped me push it to the side of the road, and I was close enough to home that a tow wasn't a big deal. But what happened?

My first thought was that a U-joint had failed -- this happened to me years ago in my grandmother's old Ford, and the sound and results were exactly the same. But when the guy was hoisting the car up onto the trailer I could see underneath that the driveshaft seemed to be turning. So what else? Something in the differential? But if that was the case wouldn't the driveshaft not be moving?

 

[HudsonHawk]

I once snapped the drive shaft in my old International. Exactly the same thing you describe...taking off from a light and CLUNK...engine running, wheels not turning. Took me a month to find a new drive shaft. Was your driveshaft still connected at both ends as it turned?

 

[AtomicEraTom]

Any car guy worth a darn will tell you the same thing you said. Don't store a battery directly on concrete. I've had it happen with brand new batteries.

I have heard of that before and I can't explain it either. Just like I can't explain why a battery left on a cement floor will go dead. Lots of people have told me this is nonsense, I say leave a good battery on a cement floor for 3 weeks and see what happens.

 

[LizzieMaine]

I once snapped the drive shaft in my old International. Exactly the same thing you describe...taking off from a light and CLUNK...engine running, wheels not turning. Took me a month to find a new drive shaft. Was your driveshaft still connected at both ends as it turned?

It appears to be. The frame of the car is constructed such that the shaft wouldn't necessarily fall to the ground if either end let loose (unlike that stinking Ford) but it doesn't seem to be sagging or drooping unnaturally. When I put it in gear I can see the shaft move a very slight bit, like a spline on the forward end has let loose and is grabbing just slightly, but the grinding noise i hear seems to be coming from further to the rear of the car.

I talked to my mechanic this morning and he thinks it's possible something let loose inside the transmission. The clutch has just been replaced, and I don't feel any grinding thru my foot when I use the pedal, so I don't think it could be that. I didn't feel any resistance or hear any grinding when pushing the car last night -- other than the resistance of trying to roll two tons of steel uphill -- so that would seem to rule out anything directly to do with the axle.

 

[HudsonHawk]

It appears to be. The frame of the car is constructed such that the shaft wouldn't necessarily fall to the ground if either end let loose (unlike that stinking Ford) but it doesn't seem to be sagging or drooping unnaturally. When I put it in gear I can see the shaft move a very slight bit, like a spline on the forward end has let loose and is grabbing just slightly, but the grinding noise i hear seems to be coming from further to the rear of the car.

I talked to my mechanic this morning and he thinks it's possible something let loose inside the transmission. The clutch has just been replaced, and I don't feel any grinding thru my foot when I use the pedal, so I don't think it could be that. I didn't feel any resistance or hear any grinding when pushing the car last night -- other than the resistance of trying to roll two tons of steel uphill -- so that would seem to rule out anything directly to do with the axle.

Hmmm...agreed if the rear axle turns, and the shaft turns, except when in gear, it's something in the transmission. The location of the noise is just deceptive.

 

[rjb1]

As an old-time hot-rodder/drag-racer I have broken almost everything in the drive train that can be broken, and sometimes it's hard to diagnose what happened.
Starting at the back, it is possible, but not likely, to break an axle shaft. A drag-racing-style start will do that, but I doubt if you take off that way. Since the axle housing supports the vehicle, and the internal axle shafts transmit the power, you can break an axle and not see any external sign of it.
Next, inside the differential housing, the internal gears (four) and the differential cross pin can break, but are also not as likely to do so. (see "drag racing starts", above). Even less likely to break are the ring and pinion gears themselves.
As you and HudsonHawk mention, universal joints are the typical weak link. We've all broken those. (In my case, I was speed-shifting a Corvette - heard "KAPOW!" - looked in the rear view mirror - saw the driveshaft cartwheeling down the road behind me.)
I'm more familiar with GM products, so I'll ask this about your Plodge: Does it have a conventional driveshaft? Early Chevy's have a torque-tube driveshaft arrangement using only one universal joint. It could fail and the driveshaft still would move if you towed or pushed the vehicle (power coming in from the rear).
Now we are at the transmission. Your mechanic may already be checking this, but you can isolate some internal problems by external means, just to be aware of what has happened. (You have to take it apart to fix it, so sooner or later you'll see what the problem is, but I like to know what is going on before going in.)
If the countershaft input gear is broken, it would do exactly what yours did. (Again, yours is old enough that it would also have a slider gear that connects the main drive shaft in the transmission with the countershaft. That also could break and cause the same thing since they are in mesh when in low (first) gear. (Modern transmissions don't have that sliding gear, which is why more-modern transmissions can be put in low without "grinding" the gears.) This one also happened to me and even though I was only backing up slowly, it sounded like a loud BANG!
A way to check things would be to put it in low gear, let out the clutch, and it should act just like it did before: NO GO Then put the transmission in high, and slowly/carefully let out the clutch. It probably won't go anywhere (which is why you don't start in high), but if it tries to go at all, and even stalls the engine, you would know that power was being transmitted directly into the transmission main shaft, bypassing the countershaft and sliding gear, and then into the output shaft. (Then to driveshaft, differential, and axles) In this way, you have at least tentatively isolated where the problem is.
If that test doesn't tell you anything, then there are other diagnostic techniques for the driveshaft, differential, and axles, but those have to be done with the vehicle jacked up, and with one person in the driver's seat and one person underneath.
I'd like to be there to assist in doing the fault diagnosis. It would bring back a part of "the good old days".
Be sure to let us know what it turns out to be.

 

[John in Covina]

U-Joints have 2 functions transmitting the spin to power the drive wheels, but they are also considered to be like a fuse in the electrical system. In certain circumstances they should break to keep the shock from damaging other drive train components. One place where this happens is if you get tire spin on a dirt surface and then the tires catch on the asphalt or cement road surface. 4WD with excessive lift often strain the u-joints and there is a wear pattern that is used to ID that. Also sometimes going thru a lot of water puddles, lakes, streams, add in mud mud can flush out the grease and introduce sift as a wear agent.

 

[noonblueapples]

This sound a lot like a broken axle.

 

[LizzieMaine]

The tow truck didn't get here today, so I took some time during my supper break to fool around with the patient a bit. I chocked the wheels, started the engine, put it in first, let off the parking brake, and eased up on the clutch. There was a low grinding noise, and I didn't go anywhere. Tried shifting into second, and then third, same results. (The Plodge has no trouble starting in third gear, but I'm not that mean.)

So, with the car running and in first gear, i carefully got out and peeked underneath -- and saw the driveshaft turning merrily. Nothing else happening. There didn't seem to be anything loose or out of place or oozing gear oil at the point where the driveshaft connects to the pumpkin, but clearly something has become disconnected.

What puzzles me is that the driveshaft was clearly and obviously moving when we rolled onto the truck last night. I'm looking at the service manual diagram right now and I don't understand how the gears can move without moving the car, unless it is, in fact, a broken axle. If that was it there wouldn't be enough power to move the car forward, but rolling the car could cause the unbroken axle to turn the driveshaft.

The noise when I came to a stop was loud, like a backfire, and shook the whole car, so whatever it was happened with considerable force. The random guys who helped me were alerted to the situation by the sound of the breakdown rather than the sight of it, so it wasn't just loud to me.

The tow truck will be here tomorrow morning, so one way or another we'll get to the bottom of this, and the bottom of my bank account, soon.

(Come to think of it, I went over a rough patch of construction along US 1 yesterday afternoon not long before the breakdown occured. It didn't feel that bumpy to me, but perhaps the axle felt differently. Maybe the DOT should be liable for the damage.)

 

[Stanley Doble]

Lizzie it sounds like a broken axle or differential. There is one other possibility. Have you had any brake work done? The rear hubs on your car are removable, they must be pulled to remove the brake drums. It is necessary to tighten the hub nut VERY tight when installing them, 225 ft lbs if memory serves. They go on a taper and depend on a wedge action to lock the hub and axle shaft together. There is a steel key but it will not hold by itself.

The key can shear off if the hub is loose. The reason I ask about the brake work is, the hub and axle shaft grow together over the years and stay tight. Unless the hub was removed recently and not tightened enough it is very unlikely the hub is loose. But it is something to check.

 

[LizzieMaine]

Ahh -- I did have both rear brake cylinders replaced last winter, and I had the shoes adjusted just last week.

So if the axle breaks at the key, it turns but the wheel doesn't. If I pop off the hubcaps tomorrow, will I see incriminating evidence?

 

[rjb1]

This whole mystery is sufficiently fascinating that I made a special trip down to our undergrad engineering lab where we have two automotive differentials, one assembled and one disassembled. It's part of a lab in which the first year ME's have to figure out how a differential works and do some analysis of one.
I wanted to make sure that I actually tried a few things and so didn't have to trust my memory on how those things work.

I think we all agree that a broken axle will let the driveshaft turn freely and not drive the car. The ring and pinion gears can turn and the differential gears, also. The axle stub will spin freely inside the housing and the other axle will sit still. So far, so good.. However, I could *not* make the system turn the driveshaft by turning an axle - equivalent to the car being pushed or loaded on the truck with a broken axle. As Lizzie said, "What puzzles me is that the driveshaft was clearly and obviously moving when we rolled onto the truck last night."
That is perplexing. If I removed one axle - equivalent to an axle breakage - and turned the other side axle, the only action was to spin the differential gears such that the axle gear on the other side spun in the opposite direction. What little bit of torque that is directed to the ring and pinion due to internal friction was so small that I could hold the input flange of the differential pumpkin still with my little finger.
However, it may be that the Plodge has enough internal friction so that the driveshaft *did* turn when pushed. Only a test would prove or disprove that possibility.

This is another thing to think about:
"The noise when I came to a stop was loud, like a backfire, and shook the whole car, so whatever it was happened with considerable force. The random guys who helped me were alerted to the situation by the sound of the breakdown rather than the sight of it, so it wasn't just loud to me."
Amen to the "considerable force" comment. It takes a lot of energy to make that much noise and cause that much displacement. The fact that there are no apparent pieces outside due to breakage/explosion means that whatever made all that noise made it from *inside* the steel/cast iron enclosure of the axle housing. Very impressive... (The only time I can remember a malfunction of that acoustical amplitude in our racing days was when we literally broke the differential pumpkin right in two. We're not at that point here, but are in the ballpark.)

If you want to charge for the answer once you get it, I'll pay a fair amount. This is the most interesting automotive mystery-malfunction I have heard in a long time.

 

[jamespowers]

If you want to charge for the answer once you get it, I'll pay a fair amount. This is the most interesting automotive mystery-malfunction I have heard in a long time.

I think we found a way to get that repair paid for.

 

[Gregg Axley]

Yes, but where is rjb1 going to get THAT much bacon on such short notice?