Farmall Cub

The right brake didn't work on RJ, my second cub from the "crooks at auction" auction fame. (John can insert the link to that thread, I've never tried to figure out how to do that). Anyway I figured out the brake didn't work trying to load RJ on the trailer. Killed it half way up, put the clutch down and right brake on (not locked together) and went for a freewheel back down the ramps. I was distracted by the slow cold wet sensation I was getting in the seat of my pants from the dry looking cushion after I sat on it. Turns out that cushion holds a lot of water. I know there's some safety lessons here about checking the brakes on the tractor before trying to drive it twenty feet straight ahead onto a trailer.

My first investigation was to jack up the right wheel and spin the tire. Looking through the slot on the final I could see the band stopping the drum but the wheel kept turning. There was also a grinding sound. So a final drive removal was next. This is what I found.


Notice the wallered out hole. I know this will need replaced.


The woodruff key is cocked with one end flush and the other way up. I don't think the drum was in the correct spot. I think the "pivot pit" was turned the wrong way causing the drum to be offset. When I put it back together I turned the pin to the other side and the drum lined up with the woodruff key.


This is the drum back on the shaft and the lockbolt tightened. Notice the gap between the drum and shaft. The brake works now but with a light foot the pedal will pulse up and down. With a heavy foot the wheel locks up.

I know I need a new drum. What's the opinion on the Shaft?

Without seeing a good (non worn) brake drum on the shaft it is hard to tell how much wear the shaft has. I think it would be wise to replace the shaft as well. After all, You are in the land of JP Tractor Salvage.

You need to try another drum to verify the shaft. If it is a good fit and not loose at the end you are ok, but if it is loose, it will have the same problem again with time. A good idea is to run a tap through the set screw hole on the replacement drum. I have found them with the threads damaged at the end preventing the screw form locking down all the way on the key.

I think it is a safe bet to say you will need an axle.
Boss

Looks to be spun pretty bad like all have said. When you have it locked down with the set bolt it's making it out of round when you apply the brakes as you said...

If one had the correct dimensions of the shaft diameter and the drum bore, it would be easy to use dial calipers to determine if one, or both, is worn. I do not have such dimensions nor any way to get them now. It would be great to have such posted for retrieval as needed.

Guys:

Different but related question. If drum is worn is it possible to turn it down like one would do for brake drums on a car?

Kajun

kajun wrote:If drum is worn is it possible to turn it down like one would do for brake drums on a car?

Short answer, yes, if not grooved to badly. On the other hand a minor groove will not greatly effect the Cub's breaking.

Eugene:

I suspected as much. Thing operates at such slow speeds and units are all mechanical so grooving should be not much of an issue.

My right brake on LoBoy gave way about 10 days ago. No time to pull .

Obliged

Bus Driver;
Very good point and I will definitely check that when I get back in to fix it and post if no one else has measured it by then.

kajun;
I know the loboy is a little tougher to look into but you might be able to figure out what's going on like I did. Block the left wheel good, jack up the right wheel and put the transmission in neutral. Shine a flashlight into the slot where the brake rod from the pedal goes into. With your other hand spin the wheel, and with your third hand apply the brake pedal. You should be able to see whats not working. In my case the brake band stopped the drum but the drum spun on the shaft.

This particular problem is as new to me as it is to you. The photo suggests that the bore of the drum is worn. Except for boring it larger and using a bushing, I know of no way to salvage it. And those selling parted Cubs probably have plenty of usable drums ready to ship. is there a section of the axle of the same diameter than could be compared by measuring to gauge axle wear, if any?

Bus Driver wrote:This particular problem is as new to me as it is to you. The photo suggests that the bore of the drum is worn. Except for boring it larger and using a bushing, I know of no way to salvage it. And those selling parted Cubs probably have plenty of usable drums ready to ship. is there a section of the axle of the same diameter than could be compared by measuring to gauge axle wear, if any?

That is a very common problem on cubs , I have seen many of them work loose and spin on the shaft. 9 times out of 10 if the drum is no good the axle will be bad too.

This circumstance suggests the PO let the brake problem run a long time after he sheered the key, probably through rough or abrupt use of the brake. In any event, that shaft would have to have been turning in the drum hub for some time. This is where a stitch in time will save nine and a good enough reason for anyone with a non-working brake(s) to tend to the problem promptly, not only to save repair costs but for safety's sake.

I am wondering if the shaft may be ok, the wear on the shaft appears to be outside where the drum normally fits.

The drum didn't seem to be in the correct spot which is I think what caused the problem. I said earlier pivot pit (meant pin) but neither one is correct. The pin is the one that holds the end of the brake shoe. It has a shoulder on one end. This shoulder was on the wrong side of the brake band which when the drum was aligned with it would slide the drum down the shaft (away from the final drive) where the lock bolt pushed down one end of the woodruff key and let the drum spin. Mr Woodruff makes a nice grinder! Don't remember which way the pin was or is now. I think I have the shoulder away from the final. I am hoping just a drum to fix it.