Banging noise from under the car...

[VowellArt]

Banging is fairly true to what I'm hearing (seemingly from directly underneath the front floorboards), problem is I'm not sure where it is coming from (sound has a way of traveling under that car), other than I know it is under the car. I thought at first it was coming from the rear end, so I pop open the pumpkin and drain the differential oil to see if anything sparkly is floating in the juice or bits of something in the bottom of the case (used my inspection camera to look around inside), no sparkly floaty stuff and no bits of whatever in the bottom either. I re-juice the differential and moved on to looking inside the transmission...nothing looks amiss in there either (the drums and wood bands look fine) and the noise isn't coming from the engine either, because when idling she's as quiet and smooth as the day I put her back together.

Sooooo, now I'm turning my attention to the U-Joint....how do you test the U-Joint? Jack the rear up and run the car whilst listening for the noise? Can I do this without starting the car?

Anybody got any ideas as to what my noise might be and or how to test for it (it's a hell of a racket and I'm sure it's not something good, just hoping it is something simple)? Don't want to tear the drive train apart until I'm absolutely sure what or where it's coming from.

[Charlie B in N.J.]

Do this carefully: Have someone with you. Preferrably someone with a bit of car knowledge. Take the floor boards out drive it and listen. You just might nail it that way.

[John Warren]

Jacking up the car and running it is a great idea. Just be careful, block the car from rolling and stay clear of those rear wheels. You will probably find it. Good luck!

[Norman Kling]

Does it seem to be making that noise when running on a smooth level road, or uphill, or downhill or on a bumpy road? Pulling, or slowing down or running at a constant speed? Some noises are in the drive line either the engine, transmission, universal joint or rear axle. Others are caused by loose body or chassis parts rattling when you go over bumps.
Norm

[Erik Johnson]

The pinion gear skipping over the ring gear in the differential due to worn or disintegrated thrust bearings will cause a banging noise. The sound travels along the driveshaft so it can sound like the problem is occurring directly under the front floorboards even though it originates in the rear end.

[Jerry VanOoteghem]

Jack up the rear wheels. Go to the driver's side wheel and grab it at the 9 & 3 o'clock positions and push it in & out. Anything more than minimal end play suggests a missing thrust washer.

For the u-joint, you can remove the plug covering the u-joint pin access and also the large grease cup and the transmission cover. This gives you something of a window into the u-joint area. Then, with the stick forward, in high gear, (and with the engine off ), look into those holes. While you're looking, have someone rock the car back & forth. You're looking to see how much rotation you can see through the pin access hole relative to how much rotation you see within the transmission, (should be almost no rotation in the transmission unless your helper is a little too energetic). Ideally, you should see only the smallest relative motion, (i.e. play), between the two. Of course, also listen for noise, clunking, etc.

[modeltbarn]

A sound in the rear end sounds like it's from the U joint because the sound travels up the drive shaft tube. I'd suspect the rear end.

[perry kete]

Do you know where your cat is?

[Jerry VanOoteghem]

Do you know where your cat is?

Excellent thought!

[Scott_Conger]

Do you know where your cat is?

and, it would be the easiest and cheapest solution

[TRDxB2]

It would help to also include the frequency of the noise and if the sound increased with engine speed vs road speed.
From past discussions I would not expect a banging noise a few seconds apart to be u-joint, drive shaft or differential issue. Given a problem in a rotating u-joint & drive shaft I would expect that noise to be more like a jack hammer. Jacking up the car would help eliminate a bad spoke or bearing. Also one past discussion, on banging, pointed to a broken part from the Mag being trashed around in the transmission housing.
.

[TonyB]

If the problem was in the magneto it would be present when the vehicle is stationary.
If the thrust washers have failed there will be shiny bits in the rear axle oil.
I my experience a UJ failure is worse at low speed and lessens once up to a steady speed.
In any case if it’s a UJ or rear axle, the axle HAS to be removed

[TRDxB2]

If the problem was in the magneto it would be present when the vehicle is stationary.

It was never mentioned if the noise was present when the car was stationary or moving or both. Why offer a solution without sufficient facts

[Mark Gregush]

Check your parking brakes, maybe a spring came off. Is the u-joint pinned to driveshaft?

[Jerry VanOoteghem]

If the problem was in the magneto it would be present when the vehicle is stationary.

It was never mentioned if the noise was present when the car was stationary or moving or both. Why offer a solution without sufficient facts

I hardly think he'd be checking out the rear end or u-joint if the sound were present while the car was not moving. As to offering solutions without facts, well, that's what forums are all about...

[TRDxB2]

Moving forward or reverse. If forward, low speed or high

[keen25]

This is really an off the wall thought but if an electric motor was attached in place of the crank, remove the plugs, jack the car up on blocks could a drivetrain be easier to diagnose? I know way out there. sorry.

[VowellArt]

Ok, my car doesn't make the banging sound when stationary, and also doesn't make the sound when in low either, but as soon as you go to direct drive (hi), the banging starts, as you reach cruising speed it goes away, until you decelerate, then it starts up again. It only makes this sound moving forward, not in reverse. Also the engine itself seems fine, I've removed the transmission inspection cover and nothing in there looks amiss, used my inspection camera to look all round the flywheel and the magnets as the engine is turned over by the crank. Since the magneto works, I'm pretty sure that the coil ring is in tact as are all the magnets. I had that problem before, where 2 plates came off the magnets (one plate put a sizeable dent in my pan's inspection cover, right about where the 2nd dip is) and the magneto didn't work, but the sound made then was in the engine, and didn't come from under the car, like this sound does.

I've thought about the thrust washers and the pinion gear also, one of the first things I did when I jacked up the rear end was to pull on the wheels to see if I had any wobble or slop...nothing moved, so I then twisted the wheels a bit to see if there was any undue slop between the pinion and the ring gear, didn't detect anything there either, that's when I moved to the transmission and looked it over.

I think I'm going to try that suggestion of looking through the UJ pin hole and note the rotation...I'm pretty sure it is the bloody UJ, it's just that I want to make absolutely sure, because if it isn't and I've replaced it and put all back together only to have the same noise again, that pretty much clinches it there...it would be something in the rear end, even though I saw nothing in the oil or at the bottom of the pumpkin with the inspection camera.

When the noise first occurred we were using the T for about a week for our main car (because the Saturn was in need of some repair) to fetch parts and to do a bit of shopping at the grocery store. It was about the 4th day when the noise started, it was noticeable, but not loud and from there it got progressively worse and by day 5 it was scary sounding by the time I got home with the final parts to fix the Saturn. If it was the pinion it wouldn't of been a gradual build up like this, it would've been an all at once I would think, but if it was something like the UJ going out, then it would take a bit of time to fail entirely (which it hasn't as of yet either, because the car still moves).

Thanks for all the suggestions, at least I've got some idea and if it does prove out to the bloody driveshaft...well I've been meaning to draw that thing anyway, probably would be a good time to do it too.

[ABoer]

Martynn ;
I am nearly sure that your problem is NOT in the transmission and drive shaft , but in the pumpkin.
I think your babbit rings are gone .
I had that problem perhaps ten or more times of other people's cars .

When did you rebuild your rear axle ???
Our advice here is Always : when you buy a Model T the first thing is OPEN the pumpkin .
That cost some money , but it saves more .

Toon

[VowellArt]

The guy I got the rear axle from told me that it was rebuilt...I never believe that and besides the only real way to make sure things are as they should be is to go through it myself. As it turned out it may have been rebuilt at some point, but it certainly wasn't in 1978 when I got it...it had babbit thrust washers. So, I put in the bronze thrust washers and changed out the bearings with NOS Hyatt bearings. I initially used the old style of inner seal, but have since replaced them with the newer versions. I'm pretty sure that the rear isn't the problem, but then things do deteriorate over time and this car had been sitting for nearly 20 years in a storage facility and later in my garage gathering dust after I got it running. Since my "retirement" I've completed the car and it has run great (with the exception of those two magnet plates).

The UJ is original to the car, so I'm thinking that it may just have finally worn out...maybe.

[John.Zibell]

Not sure this test works on a T, but on modern cars to test a u-joint lock the parking brake and going from forward to reverse. So engage the parking brake then lightly press low pedal , then reverse. If it is the u-joint you would hear a clunk as the slack is taken up in the joint.

[HPetrino]

In this case you'd need someone to drive while you troubleshoot - When I'm trying to find an elusive noise I use a length of vacuum cleaner hose like a stethoscope to find it. I've had astonishing success with this simple trick.

Good luck!!

[modeltspaz]

Martynn,
Several years ago, I developed a "Banging noise" coming from under my '26 Touring. Actually it was more of a clanging noise. Like banging on a pipe with a wrench.
The noise would emanate from under the car when I would drive the car and would round corners, go over dips, etc. It would even occur when I would bounce up and down sitting in the driver's seat. If you've met me in person (which I know you have Martynn) you know that with my girth, I can produce a pretty good bounce.
I went so far as to have a friend look and listen under the car when I bounced on the seat to generate the noise. Still, we could find the general area of the source of the noise, but couldn't pinpoint the source.
I had purchased an original Ruckstell kit from a friend of a friend about ten years prior and figured, what the heck, time to put it in. So, with the help of a very knowledgeable friend from the Orange County Model T Club, who has much experience with building and installing Ruckstell axles, we jacked the car up and removed the original stock rear end and prepared to install the newly rebuilt Ruckstell.
That's when we finally found the source of the clanging noise that was coming from under the car. We found that the torque tube had cracked just forward of the weld at the spool mounting flange and the torque tube was totally detached from the spool flange. There was no lubricant leak whatsoever, and the "Clanging noise" was the sound of the torque tube banging on the drive shaft.
New Ruckstell, no more noise. From what I've been told, this phenomenon is not common, but not unheard of.
It's worth a look anyway.
Good luck.

[Piewagon]

OK I am going to enter MY wild guess. I am basing my guess upon the time it took for this problem to show up from the time the rear end was installed as being REBUILT. The time frame of the rear end rebuild makes me think the rebuild took place BEFORE the now common CORRECTLY MADE and CORRECTLY HARDENED rear axle bearing sleeves came on the market. The previously offerred NEW SLEEVES were really bad and the bearings being replaced would not have extended their life. You said you had NOS Hyatt bearings installed but where those by any chance the SOLID ROLLER type hyatt replacement bearings? The symptoms the rear end had that I am talking about was ZERO END PLAY and good thrust washers based upon pull/push of wheels in and out. The inner roller bearings were totally worn out and were in fact cutting off the axles at the differential junction which is where the inner most end of the roller bearing was riding directly on the axle and cutting a groove in it. These roller bearings were so loose that they allowed the rear end assembly to move forward usually as the whole car came to a final stop and this would make a pretty loud clank eventually but started as just a "funny noise". It would not repeat again until the car was again pulled up to normal speed and then slowed down to a near stop - BUT - it was getting louder and louder so I parked the car for the summer. I have those axles and "bearings" (I don't think they are really bearings at all). These were on the inner ends of the axles and the outer ends were OK when I disassembled the rear end but the axles were now questionable due to the deep groove on the inner end of the axle. This deep groove was about 2 inches away from the USUAL groove that holds the axle snap ring that keeps the gear on the axle. Replacement of the inner and outer bearing of my "rebuilt rear end", along with installing 4 new inner sleeves (HARDENED) fixed everything.

I offer this only as something that might be happening if you have the parts in your rear end that I had which were available about the time frame you mentioned.

[OilyBill]

This is really an off the wall thought but if an electric motor was attached in place of the crank, remove the plugs, jack the car up on blocks could a drivetrain be easier to diagnose? I know way out there. sorry.

That ISN'T that off the wall. My suggestion if they just can't isolate it any other way, is to disconnect the U-joint and turn the drive shaft and axle over by hand. I know that on my car, it is smooth as silk, so If I found I had roughness (Even if I couldn't get a big noise out of it, because I'm just rotating it slowly, and not able to actually load it) or felt an odd throb, I would know immediately that there was something wrong with the drive shaft/rear axle. If the problem is there, it doesn't matter, because you will have to pull it out and tear it down and find out what's going wrong. And if you don't find anything there, then it's provably a transmission problem, and they ought to at least pull the pedals and cover off and see if they can determine what's going on there.
They might also try a mechanics stethescope. They are VERY handy, and they really work.

[TRDxB2]

Sound travels - another discussion about banging noise turned out to a loose pin in the crankshaft pulley.

[principal6553]

My banging noise ended up being the hand crank flopping around due to the spring detaching. The noise sounded like it was under the floorboards. Luckily a forum friend suggested that I check that.

[Mark Nunn]

Ok, my car doesn't make the banging sound when stationary, and also doesn't make the sound when in low either, but as soon as you go to direct drive (hi), the banging starts, as you reach cruising speed it goes away, until you decelerate, then it starts up again.

My car had the exact symptoms as described above. It was a worn front driveshaft bushing. I removed the plug for U-joint pin access and was able to move the driveshaft up and down with a screwdriver. I expected to see a severely worn U-joint too but it really wasn't that bad.

[Fordwright]

Sounds like a loose connection in the drivetrain. Mild acceleration keeps things tight, but when you back off the power, things start vibrating.

[VowellArt]

Looks like I'm rolling the rear axle out anyway, I'll check everything mentioned here including that bushing you mentioned Mark, thanks!

It's like I always say...fun just never quits!