605 Power Steering conversion for the tri-five Chevy's
.This a picture walk through of the 605 power steering conversion for a 55-56-57 Chevy. First this is a comparision of the 605 to the original tri-five steering boxes.
Now dismantle the 605 box. If it has a pitman arm on it, remove it first. Next there is a snap ring in the top of the 605 that holds the round top cap on. Look around the top edge and you will find a small hole near the line fittings. Take a pin punch or an awl and push it into the little hole. This will push the snap ring in so that you can get a screw driver under the snap ring and gently pry it out. Also remove the lock nut from the adjusting screw/bolt. This is left handed threads so be sure to turn it clockwise to remove. Now screw the adjusting bolt down into the box untill the top comes off. NOTE: It is a good idea to soak the adjusting screw/bolt with WD40 (or the like) for a day or so before you start.
First, if there is a pitman arm on the tri-five box, remove it. Next remove the three bolts holding the top on the 55-56-57 steering box. Remove the adjusting screw/bolt lock nut(turn counter clockwise)and screw the adjusting screw/bolt down into the top. When the top is off, look and be sure the sector is in a position so as to allow it to come out from the top of the box. It may be off center and if so, the sector will catch on the inside lip of the box. This can be moved by rotating the worm shaft.
This is the difference in the two sector shafts. You have to cut the outside two teeth off the 55 sector shaft and remove 1/8" from the top of the 55 sector.
After the cut. Note the two teeth removed.
Look closely and you can see that 1/8" was removed from the top of the 55 sector(right end). This is so the 605 top cap clears the end of the sector.
After this is done, you need to remove the adjusting bolt from the 605 sector shaft. There is a inside spanner nut that screws down inside the top of the 605 sector. Remove this and the adjusting bolt. When the bolt comes out, there will be a very thin washer on the bolt. Discard the thin washer.The adjusting bolt is all you need from the 605 sector, so you can put it aside. Place the washer from the original 55 adjusting bolt on the 605 adjusting bolt and slide it in the slot on the modified 55 sector shaft (shown above). Then just reassemble the 605 using the 55 sector. Next you will need to cut 4 1/2" from the bottom of the 55 steering box. It is best to use a power hack saw, but it can be done with regular hack saw. You will use the 4 1/2" section as a pillar block on the frame. The next photo shows the 4 1/2" section after the cut. It hasn't been done yet, but you need to drill and then install a grease fitting in the center of the pillar block. Lex's box below has the fitting installed.
One additional thing needs to be done to the pillar block. Turn the upper portion of the tri-five steering box top side down on a flat surface and look in the hole where the sector shaft came through. You will see a bushing(bronze). Look through your socket set and fine a socket that fits snugly inside the old box section, but not through the bushing. Then you can tap the bushing out of the old tri-five box and then install it in the top of the pillar block.
This is what the conversion looks like at this point.
This is a completed 605 (courtsey of Lex L.) Note the brkt. welded to the top of the frame. This stabilizes the 605 on the frame.
This is the frame brkt from the outside view. (courtsey of Chuck A)
Now that the modification is complete, it's a good time to check the 605 hose connections. The 605's have two different types of line fittings, o-ring or flare fittings. The flare fitting has a "flared seat" for the hose while the o-ring is a bit deeper and a flat seat for the o- ring. Also there are a few 605's with a metric thread. The type of fittings you have is important since it will determine which pump you use, a pump with a flare fitting, or an o-ring fitting, Unless of course you have the lines custom made.
The column also needs to be modified. I will put together another page and address that soon. One tip, if you want a tilt column, start looking for a column from a 71 to 78 Chevy or GMC van. The best fit is from a 65 or 66 Impala or Caprice, but they are VERY hard to find. Also VERY costly if you do.
Thanks to Glenn L. for his help on this page.
Mike Milam aka Mikeky aka Belair55350