I am doing a power steering gearbox swap on a '68 El Camino using a box from a '73 Z28. Unfortunately I earned myself a guided tour of recirculating balls by over-extending the rack while swapping end covers.

I have found Jim Shea's very helpful pages on Saginaw rebuild processes. They make a reference to black balls and big/small balls? But so far as I have been able to measure with a digital caliper all these balls are the same size. Was this something that got changed from big/small over to same size?

I had it all together before finding out about the different ball sizes and it worked fairly well... except for the pop while going right at the last 1/4 turn of travel. Ideas on causes and solutions to one-way pops?

Thanks,
Steve

Your problem; and the description of the problem is very challenging.

1). The travel of a steering gear (like the Z28 gear that you are using) is restricted in both directions. (The aluminum end plug when turning right; snap rings that are located deep inside the gear housing when turning left.)

If you only swap the end plug, you will have full travel in right turn but you still will have the restricters inside the gear for a left turn.

This condition will cause the following:
The rack and pitman shaft gears have a high spot on center. Now if you recenter your gear for travel (just compensating for the end plug change)it will not be on the high spot center for the rack and pitman shaft. You need to remove the snap rings inside the housing as well as replacing the end plug to get full travel and have the gear set on center.

2). The difference between black balls and the chrome balls should be on the order of 0.002 inch. You should be able to measure this difference with your dial indicator. I don't know why you don't seem to have different size balls.

3). Which brings us to the "popping" sound. I assume that you never had the same sound with your old gear. So the problem is most likely in the new gear and not somewhere else in your vehicle suspension, steering system, etc.

My information would indicate that if you don't alternate black balls and chrome balls you could get a hang-up as the balls are being scooped up by the ball return guide. This could be the "popping" sound and it is NOT good.

You want to get to the root cause of the "popping" noise.

Even though there are flex coupling and hose port issues with the more modern gears, I would recommend using the 1988-1996 Caprice fast ratio gears or the 1992 1/2-1998 Jeep Grand Cherokee gears since they already have full travel.

First thanks for the quick reply Jim.

You know what the fastest path to knowledge is? Buy the wrong part and/or assemble something wrong! I discovered your compilation of information after I had picked up the Z28 box off of Ebay based on other earlier information I had. I also discovered the different ball size issue after reassembling the box and thought it might explain my pop.

So taking it from the top:

1. Since I had the engine out I have tried a bit of mix and match. The Z28 box stock had very obvious uneven travel left/right in the El Camino. Swapping the end cap seems to provide full travel to both directions. When I checked I was able to turn the wheels all the way to the spindle/LCA stops. I have not made any offsetting adjustments and everything centers up as expected (steering wheel straight up for straight wheels, indexed steering shaft matches up, etc). This is contrary to documented expectations and I have no good explanation why, but I don't seem to need any snap ring changes as far as I can tell.

2. This one bothers me. I tried to measure more than once and I am feeling the same tightness on all balls going through the caliper. I would expect to detect 0.002 by feel if not indicated measurement. I wonder if this box has been rebuilt previously? Possibly improperly? One never knows with "classic" car parts smile.gif

3. I pondered if the pop correlated with the A-body travel extension. If the box has a worn set point that is now being exceeded. But my assembly would make that match to left turns not right. In my first ball installation I had some roughness. I tried again with fewer balls in the rack and more in the channel and that seemed to go away. I do tend to suspect a ball hang-up is causing the pop.

I agree I need to figure this out. I received an important lesson about the critical nature of steering and suspension as a teenager when I wadded up a TR3 because I left out a cotter key.

I have considered starting over with the box out of the Jeep. It looks like a *very* good match to ratio, rod size, and turn angles. It also seems to be a standard rather than an option on some and not others (less chance of getting "just another box"). Your information makes me start to wonder if I should go the Jeep route in spite of already having the Z28 box.

Well to close the loop here so to speak...

I measured the balls again (a bit earlier in the evening this time) and noted that some popped through the caliper while others slid right through. So I sorted those that slid into one pile and the poppers into another pile. When I was done, low and behold, I had 12 in each pile. These were on the order of 0.001 different and just on the edge of the measurement capability of my digital caliper.

I spent some extra time while I had the steering box opened up again and pulled out the steering limit ring from the inside. So I now should have a full A-body spec steering gearbox from a travel perspective.

I put the balls back in alternating bigger, smaller... and the pop has gone away. So I think I am good to go.

At 3 turns lock to lock, this is not the fastest box. And it still feels a bit overboosted. But I think I will live with it as is.

Thanks for the help and inspiration to reconsider and actually pull out the travel limiter snap ring.

Steve

Since you now have full travel and only 3 turns lock to lock ---- You do have a 12.7:1 fast ratio steering gear!!!

Pitman shaft travel (in degrees); divided by 360 degrees in a circle; times the gear ratio will equal number of steering wheel turns lock to lock.

89 degrees / 360 degrees X 12.7 = 3.14 turns lock to lock.

If you had a 14:1 gear: 89/360x14 = 3.5 turns lock to lock

I am sure glad you were able to separate the two different size balls and the problem is fixed!!!

Yeah those balls were more than a bit sneaky.

That I have the 12.7 ratio is good news. Just because it came from a Z28 does not mean it has not been changed sometime in the past. If the ratio does not match I wonder if the internal rod is different as well. That could explain the over-powered feel it has. I don't think I will take that end apart to find out though.

I presume there was an ID number for each of the parts within the Saginaw boxes to tell what they were? These must have been documented at one time... have they ever been "published"?

For example my worm had either F1, P1, or R1 stamped into the end and the rack had A4A.

I presume that among the multitude of other numbers on this thing are part numbers and date codes too. Unfortunately any painted ID codes on the end cap are long since painted over or otherwise obliterated.

All of the Z28 12.7:1 fast ratio gears had valve efforts of at least 24 to 30 inch-lbs. That should provide at least moderate steering effort.

There were some Camaro gears with heavier efforts (28 to 34 inch-lbs):
1985 Level IV Suspension Alpha Code XH
1986-93 FE2 Suspension Alpha Code XH

I wouldn't even think about tearing the valve apart in order to try and change the T-bar. The manufacturing sequence was as follows: The valve was roughly put together. It was then placed in a machine that flowed oil through the valve. It was hydraulicaly balanced and then the valve body and T-bar were drilled and pinned in-place while they were hydraulically neutral.

The entire valve assembly could be swapped from gear to gear but not the components.

Some of the stamped identification marks on the rack, worm, etc were generated by the manufacturing plant and never showed up on the engineering drawings. I can't help you at all with respect to what they identify.

Jim