Greetings Everyone, I had about 1000 miles on a rebuilt engine and transmission in my 26 Roadster when I suddenly lost reverse. It just wasn't there one day. Upon further inspection I realized that all 8 of the rivets holding the drum to the gear had been sheared off, allowing the drum to spin freely. The guy that rebuilt the transmission visually inspected all of the parts prior to assembly and found no problems. Does anybody have any idea what could have caused the failure?
Have you been using the reverse pedal for a brake? This puts a tremendous strain on the reverse drum.
thanks for the suggestion Bob. I haven't used it as a brake, I have RM's so have the brake band set very loose.
Sounds to me like the rivets were already loose when the tranny was put together. This isn't always obvious when doing a visual check unless you have a way to get a firm grip on the drum or gear and can give it the assembly some twisting motion. Typically, if you have some penetrant or solvent present on a clean part you'll see the liquid squeeze out from under the rivet heads indicating that they are loose. Sometimes they are loose enough that you can feel the slop between the drum and the gear when twisting them with your hands. This is a very common problem that is often overlooked.
It's not enough to just reseat these rivets. They need to be replaced. Sometimes one must tear apart 2 or 3 transmissions just to get tight drums for a rebuild. Lots of guys in the past used to just toss the old loose drums in the scrap heap but I suspect that if the drum is salvageable this is becoming less of a practice at least in some areas of the country.
David, this is not related to your question but to your having your transmission bands loose, thighten them up so they will work, i to have RM brakes and had to stop on a very steep hill with a stop sign at the top and a car coming, the RM brakes wouldn't hold and the parking brake wouldn't hold and there was a car behind me, i almost rolled it down a 100 ft embankment but the front wheels hit the drop off and turned the car sideways in the road.The pucker factor was 100%, i realize there are not many hills like this in Florida but don't count on RM brakes for anything except forward.