TR2/3/3A What is the best way to remove and replace carb shaft bushings.

[John_Progess]

What is the best way to remove the throttle rod brass bushings in the carb body and so I can replace them with the ones in the repair kit. Thanks and have a good day!

John

 

[TomMull]

Problem is not with removing and replacing but with reaming the new ones. The proper reamer is very expensive. There used to be a couple of web pages showing how to do it with a standard reamer but I haven't looked lately. Some of the SU experts will do the bushings if you send them the bodies. I don't know how that cost compares with the reamer.
I also had to cut and drill the new throttle shafts. Not too hard to do but makes the project fairly complicated.
Tom

 

[titanic]

The cast in bushings are not replaceable, except by reaming. Some people use a 3/8" reamer with a 5/16" shank. The reamer is pulled through carb and the shank acts as a pilot. Make sure not to ream all the way into the throat, but leave about a 1/16" shoulder to act as a stop for the new bushing. I prefer to use a piloted counterbore in the headstock of a lathe and use the center in the tailstock for alignment and to push the carb into the cutter.
Plan B involves purchasing an oversize piloted reamer from Moss (or other sources for $235) which reams the existing bushings for a .010" oversize throttle shaft. Not really a practical alternative for 1 set of carbs. It would be cheaper to send the carbs to Joe Curto or one of the other rebuilders.
Berry

 

[TR3driver]

I've tried it two different ways now; I think I like this method better:
https://home.comcast.net/~rhodes/Tech_Carb_Bushing_Reaming.pdf
Except turning the reamer by hand was such slow going that I chucked it up in the drill press (already installed through the carb body) and let the press turn the reamer. It also took me a couple of tries to get the right angle on the back edge of the reamer teeth, so they would cut and not just slide around.

(Obviously I used two hands for the actual sharpening, but had to use one to hold the camera for the photo.)

Here's a similar approach https://www.chicagolandmgclub.com/driveline00/1001/jasw.html
And another good write-up https://65brick.blogspot.com/2009/04/carbs-part-ii.html

The previous time, I used a method somewhat similar to the one outlined by Moss https://www.mossmotoring.com/rebushing-su-carburetor-bodies/ except since I didn't have a lathe at that time, I set up a center under the drill press and used it like a (vertical) lathe. Kind of tricky holding the carb body perfectly lined up (even with help from the center) while at the same time operating the quill (which would be the tail stock with a real lathe). The first hole wound up significantly less than perfect, but still usable with some Loctite and reaming afterwards. The others were OK.

The finish reamer I use is not made for this purpose, but I believe is an old valve stem reamer. I've forgotten whether I got it at the local "Aero surplus" store, or found it at an estate sale. The shank is very slightly smaller than 5/16" (about .308") so I use that as a pilot through one bushing to ream the other bushing. Next time (if there is a next time), I may try buying some drill rod (or HSS stock) and making my own. That should be an entertaining disaster

Drilling the new shafts in just the right spot and at the right angle was the hard part, for me. Still haven't gotten that one quite right! It appears to be important to locate the pin such that the throttle plate can be centered with the lever firmly against the side of the body. I managed to leave a gap there the first time, and over time the throttle plate wore a notch into the bore deep enough to cause it to hang up on the notch. And if you get the angle wrong, you either cannot set the idle down (the lever hits on the stop), or cannot open the throttle all the way (the fast idle screw head hits on the carb body flange).

Oh, FWIW, I'm experimenting this time with bushings from MMC that are graphite impregnated instead of oil. Maybe they will last longer, maybe not.
https://www.mcmaster.com/?m=true#catalog/121/1163/=xke8h0

 

[doc50]

This will seem to be the 'houniak method' (....it is), and I've had very good results using it.
I just open out the hole with a drill bit to a depth that will accommodate two O-rings and reassemble with a little grease. Nothing else needed, go driving.
Be judicious and make the 'surgery' a several step process until you find the right size bit.

Thom
1959 TR3
#TS34909L(O)