I'm in the process of installing an early Saginaw 525 steering box in my '40 coupe. This manual box is six turns+, lock to lock...kind of slow. The pitman arm that came with the box is rather short, the two holes being roughly 5", center to center, AND the tapered drag link hole is tiny compared to the one needed for the stock Ford rod end I'm using. Interestingly, a stock '40 Ford pitman arm has the same spline count and spacing, plus its two holes are closer to 6" on center which would EFFECTIVELY speed-up the overall ratio AND allow a tighter turning radius. The splined boss on the '40 arm measures .901" thick whereas the "525" pitman arm splined boss measures .775" thick. This will necessitate milling the BOTTOM side of the '40 splined boss to the .775" thickness as without this mod, the nut and lock washer don't have enough room to fully thread onto the sector. NOW...MY QUESTION: Even though the '40 pitman arm "seems" to fit perfectly on the Saginaw box, does anyone know DEFINITIVELY whether or not the two splined TAPERS are of the same degree? I have no accurate way to measure the tapers of the two splines? I really have no interest in a made-up, aftermarket pitman arm. Thank you to anyone with accurate info. DD
I know I'm late to this thread,,but I have swapped older Ford pitman arm with 60's-70's GM arms and the fit was perfect. Although,I think sometimes I had to take a tri-file and cut another spline in the arm where it had a factory flat that made it fit the GM box in one position. I'm sure you've already got it figured out,though.
Wow, it's been SIXTEEN months since I asked this. Appreciate the reply! I know the splines are the same. Still don't know if the DEGREE of the TAPER is the same, nor am I equipped to measure the degrees. Thanks again, though! DD
I put a 49-51 pitman arm on my Saginaw box and it's been working for 30 years. Very nice fit, no slop at all. One of the mags years ago talked about this.
I did the same install on a 40 tudor back in 1980, it's still running in the Memphis area last I heard. The fit is perfect, I got the idea from an Rod & Custom annaul edition.
Pretty simple to tell if the spline angle is the same, if it is the arm will slide on solidly with no rocking movement. Wrong taper angle the arm will rock back and forth.
It's the same taper, I have installed several of these with no problems at all. No milling of the arm is needed if you use a slightly thinner lock washer and torque the nut properly you will get full thread thru the nut.
If it has a taper and seems to fit that's good enough in my book, i just hand filed the splines on a 40 arm so it would press on the opposite direction, it's not like i was too woried about the taper being 100% corect
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