G-Machine Steering

by Gary Fanning


If parallel parking is your passion and you’re not into cruising through the twisties, do not perform this modification. One-finger steering will be a thing of the past. But if you’d like your old A-body to respond to your command then the ’85-87 Monte Carlo SS Steering Gear installed into ’70 A-body will give you all that. This is a very nice addition, especially if you’ve upgraded your front suspension with Global West or Hotchkis tubular A-arms and a larger front swaybar, 17” wheels and speed rated rubber. The new gearbox provides 12.7:1 ratio/2.75 turns lock-lock. This gearbox gives a MUCH firmer feel to the steering wheel with improved feedback from the road and quicker (immediate) response to your input. Check any G-body car with the F-41 suspension (442, Monte Carlo SS, GN, [Grand Prix SCJ??]) for the correct gear. In my case, I replaced a ’70-81 Trans Am steering gear which is a faster ratio than the stock GS, but this box provides a very noticable improvement over the TA box and might be easier to find in the junkyard.

If you can not find one in a salvage yard: Dave McGuire states: A reman unit from Autozone for $168 including tax & shipping. Their part # 6561. If you just search their catalog it is almost impossible to find so use their part # to do your search. Nobody else even came close to this price. Once you get the parts to convert the fittings, everything else is drop in and bolt up. Before replacing, it was 4 full revolutions full left to right and after it was a little over 2 1/2. Even more important, the control that you gain is immeasurable. I only wish I had done it long ago.

Your stock A-body pump fittings will need to be adapted to fit the new metric steering gear.

Weatherhead Adapters required:

1  SAE/Metric Adapter M4115 7x6x18	JIC	                $12.42
2  3-piece nut, CS/ 3/8 FJIC		WWW C510 5x6	 .42 each = .84
2  3-piece sleeve, CS/  3/8 JIC WWW C516 5x6  .36 each = .72
1  HYD. JIC/JIC Swivel Adapter  GAT 6MJ6FJx90 2.96 each = 2.96

								                       TOTAL: $16.94
85 Chevy truck coupler/rag joint-used $5.00
The above parts are all the adapters required to complete the 
swap into my ’70 GS 455.  In addition, I had to find a power 
steering bracket that would fit my 455 and clear the top of the
new steering gear since the pump in my GS was from a big car 455 
which sat too low in the engine compartment.  It was obvious that
someone had altered(read: bent) the pump tubing to fit between the 
pump and the gear.  This would not work with the adapters installed
in the gear.  I ended up with a Buick 350 power steering pump-mounting 
bracket, which works fine on the BB GS cars as long as you’re using the 
short shaft water pump. I’ve been told that the V6 brackets work as well. 
A stock GS 455 pump will work, too.  Also, you can get by without 
the JIC Swivel Adapter.  I used that to position the line where I wanted
but will probably eliminate that by bending a 90* (with a tubing bender)
in the tube for a cleaner look.  Although one of the existing lines will
thread into the new box, if you look closely you’ll see that the new box 
has a slightly different flare end that includes a small o-ring.  The JIC
adapter will have the newer style o-ring fitting that improves sealing. 
I would not use the existing connector on the new box.

Tools Required

5/8” & 11/16” flare nut wrenches
5/8” socket
18mm flare nut wrench
1-5/16” 6-point socket
Impact gun
Breaker bar
12-point 3/8” or 7/16” socket for coupler.

Also required is a new or used steering coupler/rag joint from a mid-80’s Chevy truck.I paid $5 for one at a junkyard, then sandblasted, painted and installed it. The rag was in good condition (pliable) so worked fine.

Some say a 3/8” hole needs to be drilled in the steering coupler on the shaft but the one I got slid right in place and bolted up. One stud is larger diameter than the other so it only fits one way.

Rent a Pitman Arm puller from a local parts house. The one I used came from Checker and cost $115 that was refunded in total when I returned the tool a few days later.

1-5/16” is the size of the nut on the Pitman arm. The one that was on the car came off with an end wrench but the one from the SS required an impact gun. I bought a 1-5/16” 6-POINT socket in ¾” drive and a ¾” – 1/2” adapter to fit my impact gun. That little setup cost me $40.89 so shop/borrow around if you want to save some money here. It might be possible to find a 1-5/16” socket in ½” drive. The 6-point socket was a much better fit than any of the 12-point stuff I have and I didn’t want to risk rounding the nut so bought the 6-point.

Remove power steering hoses from the steering gearbox. Drain fluid into container. I used all new fluid so you can discard the old stuff.

It looks like the Pitman arm can be removed from the box while leaving the other end on the tie rod but I removed both ends with pullers. The original Pitman arm on the A-body must be used with the SS gearbox. It is considerably shorter than the one on the SS box. I had to buy a dust boot for the tie rod (Help section of a parts house) since I destroyed the original with the puller. The new boot had to be trimmed down to size with a razor. Remove the 3 bolts that mount the gear to the frame and pull the box out of the car. Don’t try removing the Pitman nut and arm in a vise; I think it would probably be difficult to get it stable enough to put the necessary torque on it (unless you use an impact). Just makes sense to do it while bolted in the car.

Install the adapters in the new gearbox and tape them up for installation into the car. The return line required the adapter (since the original line was not included in the gearbox I bought) but I left the original supply line intact and just cut the hose and spliced it into the original pump line. If the gearbox you get has the hoses intact you can simply cut and splice a piece of 3/8 or ½” tubing in line with hose clamps. Bolt the new gearbox in place (60-80lb/ft).

There are 4 alignment “flats” on the Pitman splines, one at 3, 6, and 9, and 12 o’clock, and coresponding flats on the Pitman arm splines. There is a nub on the arm indicating the correct alignment. I marked it again with a punch in a location that was easier for me to see while under the car. Just line it up correctly and it will start to slide on the splines. When you’re sure it’s correct, “nut” it on with your impact and torque it on with a breaker bar. Torque spec is 140ft/lbs. It might help to check the space between the gearbox and the Pitman arm before you remove it from the old box, then compare when installed on the new box. It does not fit flush against the box but leaves a gap of about ½” between the arm and the box.

Connect your lines (20-30lb/ft), fill the pump resevoir, run the engine (without turning the wheel) and top off the resevoir. When you’ve reached the Full mark gradually turn the steering wheel to exercise the gear and get fluid throughout. I got no squeals from my pump/gear with this procedure. Check all fittings and connections for leaks. Verify that all steering components are in place and secure and take it for a cruise.