The old Model T has been getting in quite a few drives in past weeks. The drives have been getting longer and the iPhone even gives me speed and distance. Two weeks ago the mostly 1923 Runabout did 60 miles, last Saturday another 50. The Orange County Model T Ford Club was having another of its meet & greet breakfasts, this time at Ruby's in Orange. I got there late and everyone had finished chow but had not yet left. Folks wanted to know how this project was coming along and I explained that I was concerned about a load thrumming noise that seemed to be coming from the back of the car.
It wasn't too long before the back of the car was jacked up and both rear wheels were found to be loose, one not even hand tight! Tools were produced and the nut tightened back down. 600w oil was added to the diff housing which was low if not completely dry.
I drove home and the thrumming noise was still there. It is had to say where, but somewhere under the car. It is most noticeable when being passed by another car. Sometimes it is there under load such as accelerating from a stop, other times decelerating or even in cruise. Other times it is quiet. Its hard to pin down.
The next day I got out a breaker bar and gave the rear axle another good tightening. The nuts needed it and I have them good & tight now, even standing on the bar to get the nut to the next position and run the new spilt pins. More oil was added until I could just touch it inside with the little finger.
Something new that cropped up Saturday was a hesitation on acceleration, mostly but not always from a low speed. It got worse as time went by and it felt as if the motor was running out of fuel from time to time. This did not seem reasonable as the tank, sediment bulb, fuel line & shut off valve were all new. The carb had been taken apart and everything replaced, new float valve, new jet and new needle. The carb body was carefully cleaned and the passages blown out with carb cleaner and compressed air. The motor had been running for many hours flawlessly but now something was ailing it.
After working on the car Sunday getting the list of chores accumulated on Saturday's drive remedied, it was time for another drive to see how the car was doing. The car was found to be locked in high gear, more on this in a separate thread. As it happened, I didn't get too far on the Sunday drive. The thrumming was there just as it had been before but the running out of gas feeling was worse. I began to worry the car would quit in the street so it was back to the barn.
Last night I drained the carb float bowl. It had a little sediment but not much. Next was the sediment bulb and then a look at the screen. Both had a bit of gorp, but not enough to have caused the problem. I'll try to drive the car again and if it still acts up I guess the carb will have to come out for a cleaning. Any better ideas?
My Problem Child at Ruby's after everyone else hit the road
IMHO The "thrumming" noise in concert with the comment about the rear end being "low if not completely dry" strongly suggests the noise is coming from the rear end.
If you can get it running check the brake drums for heat like they are dragging. I had the same symptoms, felt like lack of power or lack of fuel.
Did you get a chance to grease up the rear axle dope cups?
I remember you said at Ruby's that you hadn't filled them before.
Another thing--did you check the carb float level when you disassembled it?
Mike was one of the folks who was at the meet Saturday. He went over the need to use the dope cups to lube the hyatt bearings, something I had not yet done. Yes, I sure did lube them. I cleaned out the cups of the dry old grease and pushed two full cups full into the housing then filled them again to have something to turn down later.
Yes, I did check the float level. It was WAY low when I found it. I'm not sure how it ever ran before.
One of the checks run Saturday was to jack up one rear wheel and run the car in high gear. Several folks who seemed to know about such matters thought the axle was a bit loose inside but within limits. The Rockies are loose and need adjustment, one of the things I started on Sunday. I will check for heat once the car gets back on the road. I suppose the internal bands might be acting up. BTW, the parking brake is close to worthless. It will not hold the car on even a gentile slope.
I bought a large drum Ruckstell a couple of months ago. I intend to fit that this fall once the new wheels are built. If this old axle has real problems I'm not inclined to put a major investment into repairing it.
Would a U-joint cause a thrumming from time to time?
Reid Welch blamed it on unbalanced crankshaft in his '20. IIRC, he had Dunn counterweights installed, which just changed the speed at which the thrumming occurred.
Hey Ralph! My crank was balanced as was the flywheel & trans assembly, part of the work Larry Blair did early on in the project. This thrumming sounds like something is unhappy mechanically . . .
I had a u-joint with needle bearings go haybag once, and it vibrated, but no thrumming.
You could try sawdust in the diffy....
Yes, U-joints can cause that kind of noise. So can the drive-shaft bushing. Have they been greased-a-plenty yet?
Also, an out of balance or slightly bent drive shaft can do it. Either one can start to get worse fast as the bend begins to get slowly worse. Any sort of drive-shaft whip can also rob power. The drive-shaft may need to be spun-balanced to know for sure if that is the problem. It is one that can drive you nuts. Although it is unusual in model Ts.
Drive carefully, and enjoy, W2
I would not drive the car again until the rear end has been disassembled to fix the problem. I have yet not seen a Model T rear axle that belonged to me that did not need a lot of work to be safe. One that is howling like that is terminally ill.
No sense speculating on what is causing the noise in your axle, it will be obvious after you open it up.
That noise could be any of a number of things. It could be a worn bearing in the driveshaft or the axle. It could be the gears out of mesh. The latter can be caused by worn babbit washers. If they have not been replaced by bronze, they should. Only way you can tell if they are bronze would be to disassemble the rear axle. If you jack up both rear wheels and can pull out and in on the axle, your thrust washers are worn out.
Does the "Thrumming" happen at all speeds, or is there one particular speed it occurs? If it is speed sensitive, it could be a balance problem anywhere from the engine to transmission or driveshaft.
The feeling like running out of gas could be caused by dirt in the fuel line. Even with a new tank, sediment bulb, line, and clean carb, there could still be some dirt in it. Try draining the carburetor with the petcock under it and see if there is a steady flow. You can save the gas and strain it through a coffee filter and put it back in the tank. If it does not flow steadily, or stops after a minute or so, you have a clog. Another thing would be low gas in the tank. Did you check to see if it is full. Another thing which could cause that problem would be if you have an aftermarket filter in the fuel line. They are made to work with a fuel pump but give too much resistance with gravity flow system.
I have to agree with Royce on this one. I'd say that the next step is to tear down the differential. Keep in mind that it is not actually that big of a task. I've gotten to the point where I can have one out and apart by myself in about an hour.
It's amazing what kind of wear they can tolerate, but they still need to be serviced and rebuilt, just like any other part of the car. It seems that they are ignored all too often, and they are one of the most important components of any car.
Plus, there is a chance that the sound is just going to get worse, especially if it is coming from something that is seriously wrong.
The thrumming noise is not consistent. It is often but not always present during acceleration & deceleration. An easy cruise at 35 mph or so can also trigger the sound.
One of the problems living in a suburban going urban area is that I get very little time while driving to focus on noises. The demands of driving the to me unfamiliar Model T mean that I usually need to stay focused on task. A more experienced T driver not only would better know what the noises mean but would be spending less time trying to avoid screwing up.
When the motor went in this Spring, the U-joint was cleaned and well greased. The drive shaft bushing also got a shot or two of grease from the grease cup and both got more Sunday. If they were ever run dry it was before I was working on it.
This was a running & driving car before the head gasket issues started a train of events that lead to the discovery of extensive hidden corruption deep inside the motor. Now all is new/rebuilt under the hood and I expected the drivetrain to take up where we left off. Possibly there were problems lurking there too . . .
I do hope to be able to drive the car the rest of the summer while working on a set of new wheels and getting the Ruckstell ready to install. Should I need a new U-Joint, that will be the time to install it.
There is no filter in the fuel line outside of the one in the sediment bulb. I have so far drained the bulb & line, carb float bowl and cleaned the sediment bulb screen. I'll see if any of that helps Saturday.
Paul you should swing by the model T garage put on by the Long Beach club, let them have a listen/ look see what they think. Next one is on the 17th Sat.