Shortening 3-on-the-tree steering column for power steering

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SMH1970
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Shortening 3-on-the-tree steering column for power steering

Post by SMH1970 »

Hi everyone,

Another question. I'm installing power steering (Saginaw box) in my 1970 F100 to replace the old manual steering box, and need to shorten the steering column to accommodate the larger steering box. My truck has the 3-on-the-tree manual shift column. I've seen the instructions as to how this could be done, but I have not found anyone else that has done it since then.

Has anyone shortened the 3-on-the-tree column, and if so, what issues did you come across? It seems pretty straightforward, except the part about bending the shift linkages to make sure it shifts smoothly. I've got the parts ordered for rebuilding the column, but wanted to check around before I start cutting things. Any tips or photos would be appreciated.
- Steve
1970 F100 Sport Custom, 360 with 3 on-the-tree, No PS, no PB, no AC. Boxwood green / Wimbledon white.
Plans: power steering, power front disc brakes, clean and freshen from ground up.
SMH1970
New Member
New Member
Posts: 39
Joined: Fri Nov 10, 2017 5:06 pm

Re: Shortening 3-on-the-tree steering column for power steering

Post by SMH1970 »

I decided to go for it, and see if I can figure this thing out. Following the instructions in the Technical Articles section, I've spent the last few hours trying out different configurations, and I think it will work. :thup:

When I put the column back into place, with no modifications other than having the Saginaw box installed - the loss of 2+ inches causes the shifter arm to hit solidly up against the firewall so I need to gain back the 2+ inches.
IMG_2493.jpg
However, when I removed the 'bushing retainer' from the bottom of the shaft (thus allowing the whole assembly to slide down towards the Saginaw box), I gained about 2 inches back. The retainer itself is about 1-1/8 inches long, and it was set about 3/4 inch from the end of the shaft. In this position, both shifter arms move smoothly, and don't bind on the firewall. You can see about 1/4 inch of daylight between the shifter arm and the firewall at it's closest point.
IMG_2496.jpg
This doesn't leave much room for error, and I think I will have to put some sort of retainer back on the bottom of the shaft to hold things together and allow for future adjustments, if necessary. A retainer will take up valuable space, but I think I can get a smaller bushing with a set screw that won't take up more than 1/2 inch or so.

I have a few ideas to try to 'regain' the distance I'll lose with a retainer:
- grind away a bit of the ledge/seam on the firewall, perhaps gaining another 1/4 to 1/2 inch of space (the shifter arm is really only close to the ledge/seam and not the firewall itself)
- the rag joint isn't tightened down in the second photo, and that should give me 1/8 to1/4 inch
- I'd like to get a U-joint to replace the rag joint, and this 'might' also give me a bit more space (I haven't got length dimensions for a U-joint, but the rag joint and clamps take up about 2.5 inches - a U-joint close to that length would work)
- if anyone has any other thoughts please let me know

I'm not sure that all of these ideas are possible/feasible, but I'm confident I can make it work. If so, then I'll just have to shorten the column and housing a bit inside the cab, so the steering wheel can stay in roughly the same place (and not be too close to the driver).
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- Steve
1970 F100 Sport Custom, 360 with 3 on-the-tree, No PS, no PB, no AC. Boxwood green / Wimbledon white.
Plans: power steering, power front disc brakes, clean and freshen from ground up.
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