New Member Needs Help

[emf]

Hello, I'm new to this forum, but I've been on the Ford Barn for a little over a year. I have an early 28 AA firetruck that has a bit of a problem. There is a rumble in the engine that seems to be there only when I'm in gear and under a load. I've had the lower half of the engine apart several times looking for bearing problems, especially the center main, but all looks good. In fact, the babbit looks new. This truck has a pump just after the first half of the drive shaft that is driven by the transmission final drive. I'm afraid that I may have to go inside to investigate. The rumble that I hear and feel is regular and seems to be in time with the drive shaft, but it's hard to tell. Would anyone have a pump diagram that could help in this situation? If I could remove the pump from the drive line, it would help, but I'm not sure that can be done...
Thanks in advance.

Frank

[Bob C]

Maybe a bad u-joint or transmission bearings.

Bob

[Stakebed]

Hmm does it vibrate at a certain speed? Typically u joints least in modern open shafts its speed and load related. Can you remove the floor boards and go for a drive with a buddy and a mechanics stethoscope, you drive get it vibrating and have your buddy probe around like trans case, pump case, u joint housings. Should be able to narrow it down.

[1crosscut]

Hello and welcome. Post your location and perhaps a fellow AAer may be close to you. Fire trucks are few and far between so finding someone that is familiar with the pump internal set up may be a challenge.
Good suggestion from Stakebed on having a buddy with a mechanics stethoscope ride along checking things. I know you said it makes the sound under load but have you tried jacking up the rear wheels and duplicating the sound? Even if the noise is not audible with the wheels off the ground maybe there is enough low level noise to pick up with the stethoscope while on jacks.
If you don't yet have one of the stethoscopes (Harbor Freight has them) use a looong screw driver to probe for the sound. Place the handle tight against your ear and the tip to the engine etc... often will work well for finding sounds.
Could it be in the transmission?? Does the truck have the dual high transmission too?
Pictures of the drive train from underneath might help visualize the set up for us.

[emf]

Thanks for the replies, I'm in Hudson, NY (south of Albany). I have jacked the rear wheels off the ground and the sound changed from a pounding noise to a dull rumble. At first I thought the sound was from the pump trying to engage while I was driving, but with the wheels off the ground, the sound is quite different. This truck has a regular 3 speed transmission with no dual drive set-up. I'll try to get a photo of the undercarriage, thanks. Trying to get to the u joint looks to be a challenge...

Frank

[emf]

OK, here is a shot of the undercarriage. The red case in front of the cross-member is the pump gear box. There is a lever on the driver’s side that engages the pump and puts the final drive in neutral. The transmission is placed in high gear while pumping. I’ve hesitated putting the pump in play, since I don’t know the condition of the pump. I would guess that there is a u-joint after the cross-member in front of the drive shaft, but is there also a u-joint just behind the transmission?

Frank

[1crosscut]

Yes there is a u-joint behind the transmission. Did you try using a long screw driver to listen and pin point the location of the sound? Try disconnecting the speedometer cable from the drive shaft to see if that helps.
Another thought, is it possible that you have flat spots on the underside of your rear axle housings that the roller bearings are bumping over causing the noise? By taking the weight off of the wheels the roller bearings will be riding on the top/smooth side of the axle housing races.
The truck looks to be fairly recently restored. Did you do this yourself or was it done by someone else. Just trying to get a feel for how deep you have been into the workings of your truck.

[emf]

I've only had the truck for 2 months or so. I have only cleaned it up and not much else. I have the history of the truck since new and I am the second owner after the original fire company. It was purchased from Howe Fire Apparatus in 1929 by South New Berlin Fire Co. South New Berlin, NY. It looks like a re-paint, but there is a small ding in one front fender (within the last 2 years), but there is no other paint under the surface that I can tell. I will be digging further this week-end. Any AA parts suppliers out there???

Frank

[1crosscut]

Nice that you have the entire history of the truck. I'm the third owner of my truck and also know it's complete history. Most all of the vendors have "some" parts for the AA's. The 28's and early 29's don't have quite as many parts available for them as the later trucks. Many parts can be found through this forum though. Some persistence and searching is necessary at times.
Vendors I like to use have been Bert's Model A in Denver Co. and Snyders Model A.
All the engine stuff is the same as the A's. From there it can be a whole different ball game.
Sending you a p.m.

[emf]

I know I said that I'll be checking the integrity of the u-joints on Saturday, but I'm just trying to do my homework ahead of time. Can anyone tell me if the u-joints for the 30-31 trucks will fit the 28?

[chief5215]

I also have a early 28 aa fire truck. What fire pump do you have. Mine is a hale. I have a parts breakdown of my pump. There is a coupler in between my pump and transmission on mine that has fine splines in it. I could see where it could make this noise. Let me know if I can help .

[emf]

Photos?? There is one part on my pump that says Hale. It's a large gate valve on the output port with a handle that opens and closes 90 degrees apart. It has a square 6 bolt flange. see the photo. If you look at the photo of my pump, maybe there are similarities. A diagram would help.

[emf]

Well, after a weekend of investigating the source of the noise, I've discovered that a new universal won't be necessary. The center main bearing in the engine is shot. When I dropped the main cap, babbit came off the shell in sheets. I guess now I'll pull the engine and check the top half of the bearing. Not sure what the plan of attack is to be, but it is what it is...

thanks to all for the help on this one...

Frank

[Stakebed]

Ouch, least youve discovered the source.

[1crosscut]

Dang Frank that is not news any of us like to hear. You can beat this.