Source for throttle shaft bushing

[J1]

Why are bushings so hard to find? Seems there are some being sold on eBay though at a high price and/or not exact fit thus requiring drilling the carb.

After surfing online I somehow ended up at www.carburetor-parts.com so I'd like to ask you experts if this particular bushing might be a good option for my 34-3... http://www.carburetor-parts.com/Brass-Throttle-Bushing_p_447.html

I've been told (though not confirmed by me) the bushing should have inner diameter of 8mm (0.315") and outer diameter of a little less than 10mm (0.394"). The above item is 0.312" and 0.386" so that seems pretty darn close. Yes?
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you can cut a valve guide to do this.......
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[Vanapplebomb]

Go to your local industrial supply (eg, granger, applied technologies, etc...) and order 5/16 id x 3/8 od x 1/2 inch long igus iglide T500 bearings. Chuck up the throttle shaft (originally 8mm) in a drill press or lath and lightly sand down the surface of the shaft to smooth it out.

5/16" is slightly smaller than 8mm, so it is a better fit on the old worn shaft, especially after sanding a few thou off the diameter. I found an 8mm id is too large most times on old Solex shafts. If need be you can always open up a 5/16" bearing to fit very nice. You can use a standard drill bit to drill the bore out for the new bearings. Just don't go too deep or you will have junk throttle bodies. Get the holes misaligned too much and the shaft will bind. It isn't too hard. I have done it on a few carbs. These are very good bearings. The cost a couple bucks a pop when you buy them individually, but they are better than bronze bushings.
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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[raygreenwood]

[J1]

[rugblaster]

I have some bushings.....I wasn't aware you could do the operation without machining the carb body. How do you do that?
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[Vanapplebomb]

For using anything other than the stock size bushings, you need to drill out the throttle body for new bearings.

Ray, igus makes some really good dry run engineered polymer bearings. We are starting to use more and more of them in machine design work. Bearings like these iglide T500 bearings appear to work better than traditional oil impregnated sintered bronze bushings. Th bronze bushings suffer from lack of lubrication at low speeds, particularly in ocelating/pivoting motion. It just isn't enough to get the oil out of the pores. The igus poly bearings with solid lubricants impregnated in them work very well for such aplications. The fiber reinforcement makes them super tough and hold their shape as well.
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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[raygreenwood]

[66brm]

Ray, suitable for lifter bushing a T1 case?
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[Vanapplebomb]

No point in spending the extra cash on dry run bearings when you have a pressurized lubrication supply...just my opinion.


Back to carb bushings. These are the one I have used. Between their dry run lubrication properties, PV rating, and much larger surface area, they will last a very long time.

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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[raygreenwood]

[AlteWagen]

Great info here!

Van, what bit size are you using to drill out the TB? After the press fit do these bearings allow for fluted reamer to match TS size?

I have a stack of PICT 28s and 30s as well as a few sets of Kadron TBs that could use the treatment.

Thanks!
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[modok]

A large % of the kingpin bushings on big trucks are plastic.
Actually, steel shell with a thin layer of bearing material attached somehow.
The head mechanic at local UPS tells me they last 2/3 as long as the bronze ones we replace them with. (which is surprising, honestly I thought they'd last longer)
The polymer material is attached strongly to the steel shell.
I have smashed a few flat and using them as soft jaws for the vice and the plastic does not fall off.
I expect these kingpin bushings are similar to how you would make polymer lifter bushings.

Poly bushigns seem like a fine idea, but..... if a guy already has the tools to work metal, then of course use metal. Which will hold up better? who knows. They will both work great if done right.

I'd not use a drill. If you DO use a drill, make it a self centering drill like a uni-bit, or single flute. A general purpose "drill bit" is for making a hole, not enlarging one. Finish size with a reamer. Of a bushing is supposed to fit a certain size hole then make a certain size hole! or make a hole and measure it and make a bushing to fit. All of the tools for valve guides can be used here, or, you can make your own method, but one thing that will not change any time soon is the drill bit

Alternative sharpening techniques can be used to make a drill bit MORe like a reamer but I will not be discussing this. I have said too much already

[Vanapplebomb]

About the size of the hole; igus has specs for press fit, etc. but for this, a 3/8 hole works well. The bearings are slightly oversized on the od for a nice press fit. Just be careful not to deform the soft aluminum throttle bore when installing them. Yes, they can be opened up once installed for a good fit. This is why I recomend 5/16in id bearings rather than 8mm. 5/16in is slightly smaller than 8mm, which gives you wiggle room to open stuff up if needed. Besides, i guaranty that those 8mm throttle shafts are not actually a full 8mm. 5/16in has been a very good fit in my experience with only one needing to be opened up slightly.
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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[raygreenwood]

[modok]

Well, I didn't think it was the same, but, it is an example of a steel shell poly bearing.

These kingpin bushings can't be THAT bad Ray, they are OE equipment on the majority of trucks on the road.
They are not "easy to replace", and the king pin seldom survives.

I think they were used because they probably were cheaper to produce.
Sad, but that's probably the only reason.

[raygreenwood]

[Vanapplebomb]

I have seen those kind of metal backed poly bushings. Yes, the poly lining is totally different than these bearings. That poly material is soft and deforms easily, which is why they use a thin layer on a metal backing. The ones I have seen are just a few thou thick, just enough to provide a slick surface but not enough to be able to significantly deform. A solid bushing of that softer poly lining in a kingpin bushing application would not hold its shape for long at all.
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1800 Type 4 Berrien 295

http://www.thesamba.com/vw/forum/viewtopic.php?t=487021

[henry roberts]

thread resurrection.

i am going to give this a go but it is all totally new to me so i have some dumb questions.

1. do these need to be installed blind or can i just open the throttle shaft hole straight through and trim the ends?

2. if blind, is there any way it can be done by hand? from what i have read, hand reamers have a tapered lead in. (and i don't have access to machine tools)

3. is a straight flute reamer or a twisted flute reamer better for the soft alloy of carbs?

4. would the bushes hold in place better if they were pressed in to holes reamed to 9.5mm as opposed to a 3/8". .374" vs .375"

thanks.

edit:

5. can i get away with reaming from a 9mm hole or do i need to get a 9.2 or 9.3mm drill?

[Machecoul]