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One of my tasks to complete on the 1931 Series 43 before the engine returns from the shop, is to rehabilitate the flex joint where the front end of the torque arm attaches to the cross member of the frame. The joint seems to be made of 2 plys of fabric which are (at least: were at one time…) coated with rubber; very similar to the construction of cross-ply tires. It is quite rotten although intact.
Although this seems pretty straightforward, one thing of interest: I placed a jack underneath the arm when removing the bolts, as it had some downforce on the forward end, which the joint was supporting. I have no idea that this is anything but normal, and the only possible adjustment I see would be to loosen the u-bolts holding the rear axle housing to the springs and rotating the axle. I see no need to disturb this as I can easily reassemble this as-is. It does occur to me that someone has already repaired one of these and so may offer advice on the material to use and how it might be best accomplished, so I hereby solicit same.
Photo:
another
Hi Randy. The material is rubberized belting. Like the drive belts used with old tractors, steam engines, conveyor belts etc.
If you cannot find any locally, measure your old material. I have a roll of 8″ wide belting, It is a bit thinner than the original, so i use three layers. It usually is either 3″ wide or 3.5″ wide.. I can cut you whatever you need. Drilling it is easy,
The preload on the torque arm is something that used to be taken care of. The Series 80 rear axles had a sleeve/bearing on the rear axle housing that the leaf springs were clamped to. the sleeve allowed the axle housing to stay in the location that the torque arm was holding it.
On the later axle housings this sleeve was eliminated, and the curve of the leaf springs exerts a lot of pressure on the torque arm and the soft-joint of the belting.
To make installation of the new belting material a little bit easier, leave the rear axle on the floor and only lift the from top your car, the compressed rear springs will exert much less pressure not he front of the torque arm.
Let me know if you need some of the belting. I can mail it, or bring it to Branson if you are coming.
Greg Long
Would mud flap material work this?
I’ve used cloth reinforced rubber mud flap material as cushion material when mounting radiators and it may work in this instance as well.
The material must be strong in tension. You can see the stretched section in the photo Randy posted. The stretched section shows the broken cords and compressed opposite side of the torque arm.
This is why drive-belting is used, it is designed to be strong in tension as it transfers power from one wheel to another.
If a mud flap has multiple layers of fabric, then it might work ok. But the mud flaps I’ve worked with only had one layer of cloth inside. They do make wonderful vibration isolator pads. The single layer of cloth keeping he rubber intact and not splitting and being pushed out from under the heavy machinery.
Old bias-ply 4-ply tire sidewalls would work. But radial tires often only have one or two layers of cord in their sidewalls. I was surprised to learn that Semi-Truck tires have only one layer in their sidewalls. but it is a woven steel cord. Semi truck tires run at 100-120psi, and are rated for 6000# loads.
Greg Long
Randy: I do have some ‘extra’ .
Do you want me to bring some to Branson? Are you going to attend the winter board meeting?
Greg Long
I replaced this mointing with a (scrap) piece of belting that I gdot from a local ruck repair shop. Greg is right that it needs to be strong . I used a piece which was about 1/4″ or 5/16″” in thickness. This was on my 1929 Pierce and it works fine. Be sure to use the reinforcing washers from the original.”
Hi, Greg, I have some of the same material; thanks for the offer, though, you are always ready and willing to help and that is an enormous addition to the joys of the Pierce-Arrow Society!
Alas! I cannot make it to Branson because of another commitment that weekend; however I was at Jim Cox’s shop last week to pick up my ’31 transmission and he has some real beauties to show you all. You will have a great time I am sure!
Greg, one more question: do you know about where the center holes for the torque arm should be, vertically? I am trying to flatten my old flex mount out to get a measurement and the holes are definitely not centered between the mount holes on the top and bottom end. I think just getting them about right will be close enough.
Centered between top and bottom holes. If you look at the top and bottom brackets on the frame crossmember, and then look at the gap between them, there is not a lot of room once the end of the torque arm is in the gap.
The torque arm is pushed up by the ‘reaction’ forces on the rear axle as it drives the car, and the torque arm is forced down by hard braking action on the rear brakes. Which way was your arm pushing/forcing the distortion in that flex joint? I’m guessing down.. the odds are 50/50. LOL
I’d set it up so that the torque arm is centered in the gap between the brackets on the frame crossmember.
Greg Long
Mine was pushing down some; I put a jack under the arm as I removed the bolts, just in case, but it was not a lot of force. The flex was distorted downward, though. The Car was sitting on the wheels but with no engine and trans aboard.
In cleaning some of the parts of the torque arm mount I found stamped on one of the washers the name “Spicerâ€, the patent number 1580747, and the date April 1937.
When I looked it up the patent was for a type of flex joint which used fabric reinforced rubber discs. The washer fits between the layers and has a round lip on the outer edge to grip the flexible members.