Mark, here is the post that gives the sector shaft sizes. I didn't know how to bring it forward other than to reply to it.

Mark

1956 Mercury M100
1955 Ford Fairlane Club Sedan
Delta, British Columbia

I didn't notice the step, since I didn't remove the sector shaft. It may be very close to the bearing. I measured 1.127 just above the spline. Sorry for the crappy original pix. I will look for the step when I get home tonight.





Interesting. Do they all fit the same splines on the 1 1/8" shaft? In other words, will my '55 Pittman arm fit my '57 box? If so, the logical question is... which one is longest, and will give the fastest ratio steering?



Thanks for the follow-up, guys! This forum is great!



Edit: The actual sector shaft size is 1.25" after all. The step down to 1.125 is under the lower bearing housing, so I didn't see it. It was kind of hard to measure, but I could just get the caliper tips in the gap between the shaft and the housing. Thanks again for the info.

Marv





Charlie:



I could not read the slide scale well enough from the picture. Thanks for the clarification.



If the reading is 1 1/8" there is something wrong. The only place I could get a 1 1/8" reading or more exact of 1.270" was on the spline area.



The 3 tooth has a raised step from 1 1/8" to 1 1/4" just above the spline. The 2 tooth sector shaft does not have this raised step to a larger shaft it is 1 1/8" straight through, both were machined to accept the same pitman arm. The 55/56 cars 2 tooth and 3 tooth with or without PS took the same pitman arm.



The birds according to my parts book have a different pitman arm each year and the 57 cars had a different pitman arm for PS or non PS.



Here is a pic of the spline and step on a 3 tooth. This sector shaft came out of a 57 bird also.







marv

Marv, The dial indicates the hundredths and thousandths. It is indicating about 1 1/8"


Lawrenceville, GA

I think you are mis-reading your vernier.



If I see correctly the dial is between the 20 and 30 and looks past what would be the 25...more close to 26 so would be the 1 inch on the slide scale plus the 0.26 on the dial so would be a total of 1.260 inches. This would be a 3 tooth shaft. Congrats on the bird part find.



Here is a pic of a 3 tooth I took this AM. The reading I got was 1.2495 which is 0.0005 under 1.25 or 1/2 thou less than 1 1/4 inches.



1.125 equals 1 1/8 inch

I just acquired a 3 tooth steering box from a 1957 t-bird with a 1.125" diameter sector shaft. Will post pics w/update.











Number on casting is AF-3550-A

There ia listing on Ebay for a completely reconditioned integral type power steering box modified to mount the same as the original 55-56 box.You have to shorten the existing upper shaft and use a coupler to join together like the later model Fords.Pricey though at $600.00 plus shipping.

  

I'm not sure about the steering ratio situation, but 55,56 - 2 tooth boxes had durability issues. They tended to develop flat spots. A friend had a 56 club sedan years ago that had a major flat spot in the box. However, the later boxes incuding the 57s weren't ammune to that problem either, I know from experience. 1958 & later boxes are a resirculating ball design. However,they don't just bolt into earlier models. One issue is the horn design which is totally different...

Paul

[quote]oldcarmark (4/25/2011)

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Is there a way to identify the better 3 tooth sector shaft box



Just curious, but is the faster steering ratio on '55 birds due to the # of teeth, or some other component change in later models? Was the 3 tooth upgrade for improved strength/durability at the cost of slower steering?

6 VOLTS/POS. GRD. NW INDIANA

Mark

If you measure the sector shaft it will tell you if 2 tooth or 3 tooth. The 3 tooth is 1/8" larger diameter than a 2 tooth. 3 tooth should be 1 1/4" diameter. I will check the numbers on my car tomorrow as it has the 3 tooth box.

marv