1947 Farmall M Carb work - Throttle Shaft Bushing RR

Ken Christopherson

Well-known Member
Hello all,

First and foremost, I hope your Easter weekend is off to a great start. I've been plugging away just cleaning and scraping some of the small parts that I was able to bring home from the tractor. Today I made a go at rebuilding the carb - got 99% of it handled, but the only thing I haven't done is installed new throttle shaft bushings. I was looking for pointers on R&R of these. I thought I might be able to tap them, and thread a bolt into them with a base, and nut, to use as a puller. The setup would make more sense with photos, but I'd have to make it first. I'm also working on Episode 8 (which is just a carburetor rebuild episode), that even goes through my confusion as I reassemble (Shouldn't have waited a month to put it back together).

I'll include a link to the new episode once I get it edited. Until then, I'm still waiting for the machine shop to get the head and block done. Take care, and as always.. Thanks for any input.
 

99 times out of 100, a new throttle shaft will take care of the slop. I've had to replace only one throttle shaft bushing, and it was already worn egg shaped, paper thin at one side. Don't know how that happened, but it was easy enough to remove what was left.
 
Most of the slop (groove) was in the old shaft, and I was originally going to use the original bushings (I test fitted the new shaft into the old bushings). Didn't seem like there was much play, but after I finished complete assembly of the carburetor, there seemed to be a bit more play. Maybe I'm just being picky - there is plenty of bushing there.. I just figured since I've got new ones I might as well try to replace them.
 
Just be sure to get the throttle plate installed
correctly---so it closes off the bore when at an
idle. A veteran IH mechanic got our SMTA throttle
plate in backwards, & it wouldn't idle below
probably 900- 1000 RPM.

Same for the choke plate & shaft. The cub which I
just got had the choke shaft 180 degrees out of
register.
Jim
 
I think your idea is just fine. A 10-32 machine screw and nut with a thick washer pulling on a 1/4-20 nut with the threads drilled out might works as well and it would not "expand the bushing". Jim
 

Turn a 3/8-16 tap into the old bushing about 6 turns. Then you can remove the tap and turn in a 3/8-16 bolt finger tight. Using a 1/4" punch, tap the bolt with bushing out from the other side. Works for me. Bob
 
Your puller will work fine.

I haven't done one in over two years but it seems like on some there's slot or groove cut into the "drive" side bushing. Look at the one that comes out and see. The slot has to have a certain orientation. I could be wrong and thinking of some other carb.

Throttle shaft and bushing fit is a good place to be picky.
 
I didn't see a groove in mine, but I did see two holes in the bushing. I will definitely pay attention to the orientation of the openings in the bushing. Thanks for the heads up!
 
Very good tip, Brownie. I'll double check that to make sure it is closing off the throat completely. I believe it is, but it doesn't hurt to double check! Thanks!
 
Learned that from a good friend several years ago, who has since passed away. He worked on a lot of tractors,
mostly IHC and J.D.. Have things, every once in a while, that I'd like to ask his advice on.
 
(quoted from post at 18:36:45 03/28/16) Learned that from a good friend several years ago, who has since passed away. He worked on a lot of tractors,
mostly IHC and J.D.. Have things, every once in a while, that I'd like to ask his advice on.

Wishing I had a good friend like that near me when working on my tractor that I could call on. When I was a kid growing up I could have learned a lot from my families if I had taken the time to learn back then.
 

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