'47 Cub governor adjustment advice

[riverbend]

My new to me Cub never had much throttle response. It was dead for half of the operator throttle range. A notch more open and it would idle. Two more notches was all I ever got. It sounded like it was running at half throttle. There was an external spring pulling the carburetor plate shut. Removing the spring put idle at the very first notch. two clicks up and it will over speed.

It has a new carburetor. The linkage between the carb and the governor needs to be shorter to make the pin slide through the clevis and the arm on the governor but the treads on the linkage are right up against the governor arm.

I'm guessing that all the governor adjustments are off. Are there baseline settings to get it in the ballpark ?

This tractor has a magneto and it does not look like there is a place to hook up my tach. Any good ideas how to measure the rpm ?

 

[47fivewindow]

Place the carb throttle butterfly in the all the way open position. Push the governor to the all the way forward against the stop. Adjust the linkage to line up with the holes. Now when you open the accelerator notch thing all the way forward the carb should go all the way open. Now it is the gov. job to sling the weights out and pull it back to the hi unloaded position (slower) If this is not happening the governor is to blame and need to be taken off and inspected. Hope that helps.

 

[riverbend]

When I open the throttle the arm on the rockshaft moves back (towards the carb). The instructions say to move the rockshaft arm towards the carb and adjust the clevis to fit the pin. The clevis is so far up the throttle rod that the end of the rod hits the rockshaft arm when it all the way back.

Are there baseline settings for the speed adjusting screw and bumper spring ?

 

[47fivewindow]

Rockshaft all the way back. Butter fly all the way open, Are you sure the clamp on the carb throttle shaft is tight and not upside down? The speed adjustment is for max speed and should not affect cause over speed until the spring is streched all the way. The spring should be pulling the carb open and the gov should be pulling it closed I think mine are using all the rpms the spring will allow, but as I remember the stock setting is about a quarter inch from all the way.

 

[Jim Becker]

The rockshaft is keyed into the governor. Sometimes that connection gets worn, allowing the rockshaft to turn relative to the internals of the governor. Check that area for looseness. Any looseness can cause problems, including the one you are experiencing. Some people have reduced the looseness with one or more of: a new key, a shim, JB Weld.

 

[riverbend]

There is only about 3/16" of threads showing behind the clevis on the throttle rod.

The key and the slot in the end of the rockshaft extension are a reasonable fit. The piece that the extension shaft fits into has quite a bit of slop. Looks like the governor has to come off.

 

[riverbend]

I finally got time to pull the governor and found that some of the play in the rockshaft is due to somebody using a cotter pin rather than a roll pin to secure the cast spring bracket to the rockshaft.

It looks like the governor weights are rubbing on the housing.

Any ideas what to check ? The governor spring is pretty stiff but I can't find the spec for the spring rate anywhere.

 

[Jim Becker]

I can't tell for certain from the picture, but it appears to me that your governor tension fork may have one side broken off. (One side is normally longer than the other, but both should be long enough to engage the thrust bearing.) How does the thrust bearing look? It should have three pieces, two races and a carrier between them with a circle of ball bearings. If all those pieces are in order and the weights still rub on the housing, the weight pivot pins and related points are probably worn excessively. The fix for that is usually to find a complete governor shaft assembly with the weights etc. that is in better condition.

 

[riverbend]

It feels like most of the play is in the bearing at the base of the weights. It is hard to tell 0.003" by just wiggling the weights but they don't have a lot of play. The thrust bearing feels fine. Both legs are on the fork, the picture is at a bad angle to show them. I'll have to take it apartfarther to check for wear.

 

[riverbend]

Replacing the pins with 1/4" bolts removes most of the pay from between the weights and and the carrier. Now it looks like the slack is between the weight carrier and the shaft. How is it attached to the shaft ? The parts book does not show it disassembled but the service manual talks about using a 0.020" feeler gauge between the gear and the governor base when pressing them back together.

When I look for a used governor the ads say 'removed from a non-running tractor, but all the parts move'. Seems a lot like a pig in a poke.

 

[riverbend]

I wound up getting a used governor from Burch Store down in North Carolina. I talked to them and they said 'Ya know, the newest one is 50 years old' and if there was something wrong with it they would make it right. I have not installed it yet. I got sidetracked by taking my old one apart.

I was a little surprised to see that there is no bearing in the housing between the drive gear and the weight carrier. It looks like a plain 5/8" X 3/4" bushing. Just measuring with a caliper, the ID was about +0.003. The shaft showed very little wear. The ID of the carrier was where there was the most play. The ID measured 0.634" so it was rocking on the shaft. The pivot pins were undersized, 0.246". Replacing them with 1/4" bolts removed a lot of the play between the weights and the carrier. The carrier looks like it had tabs that were brazed on.

 

[47fivewindow]

That looks like you're not the first one to try to fix this. Time to punt. Install the used one.

 

[riverbend]

If the hole in the carrier could be bushed back to 5/8", the rest of it is repairable. I'll add it to my pile of future projects.

How do you measure the rpm on a tractor with a magneto ? Is there a place to hook up an old style dwell-tach ? A new timing light to measure rpm seems like a tool I wouldn't use very much.

 

[used red MN]

I was a little surprised to see that there is no bearing in the housing between the drive gear and the weight carrier. It looks like a plain 5/8" X 3/4" bushing. Just measuring with a caliper, the ID was about +0.003. The shaft showed very little wear.

Why are you surprised at a bushing being there? What do you think rod and main bearings are? Essentially bushings but pressure lubed. Trying to re-bush it and bring the tolerance back to the gnats butt is probably a waste of time. The pressure from the governor spring and the centrifugal force of the weights are always trying to shove that shaft out of the front of the engine. The thrust bearing is what is most important.

 

[grandpa Love]

I have followed this post with great interest.......and I have to say out of nearly 100 cubs that have come through here I've never had this many issues with a governor . And they are all working correctly when they leave here. I guess my test is too simple, drive up hill, tractor revs up and maintains rpm ( or mow through tall grass and it revs up to keep a consistent rpm). Or drive down hill and the motor slows down, doesn't over rev. .

 

[used red MN]

How do you measure the rpm on a tractor with a magneto ? Is there a place to hook up an old style dwell-tach ? A new timing light to measure rpm seems like a tool I wouldn't use very much.

Search “laser tachometer” priced from $10 to $25 and up, one from Harbor Freight is $39. Or 3rd in a Cub is 7.3 mph wide open. Use your phone and get it to 8 mph and call it good.

 

[riverbend]

I have followed this post with great interest.......and I have to say out of nearly 100 cubs that have come through here I've never had this many issues with a governor . And they are all working correctly when they leave here. I guess my test is too simple, drive up hill, tractor revs up and maintains rpm ( or mow through tall grass and it revs up to keep a consistent rpm). Or drive down hill and the motor slows down, doesn't over rev. .

There is more... The alignment pin in the 'new' housing had been squashed by someone not getting the guts of the governor lined up right. The hole in the end of the rockshaft in the old housing is oversized, the roll pin drops right through. If I can't pull the squashed pin I'll swap the rockshafts.

 

[riverbend]

 

[riverbend]

Did the same guy who marked the Super C flywheels mark the idler gear on these engines ? It looks like barely a scratch on the front side of the gear.

 

[560Dennis]

Here is an example of governor inspection and repair to look over if you want.

Inspection & repair of a Governor

This post is to help with the disassembly, inspection, repair, and re-assembly of a Cub governor. In the parts book, group 12, page 18 is the diagram, part numbers, and description. I have tried to use the same verbage as the parts book, in order to avoid confusion. The numbers in ( ) are the...

farmallcub.com

I see that the intent was there to repair weight hud with braze , but also see that the bores and alignment is questionable and this cause the weights fly out and rub the housing.