1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Steering gear box out of true.

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Old 06-17-07, 10:37 PM
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Steering gear box out of true.

Sorry long post. Need to tune my manual sterring box on an 83. Don't have the special Mazda tools. Just a back yard mech. Had it all apart ( stupid me). Last thing to tune then ready for road after 2 years. Any tips would help.
Old 06-18-07, 12:16 AM
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Steering Gear Restoration By Bobrx-7

Get Connected to the Ground Again

The following entry is in draft form. All of the procedures have been done at least twice and are believed to be correct. I will be verifying a couple of details in the next week or so (late March). Any changes will be noted in a revised version. Please feel free to e-mail me at; bobrx7@yahoo.com with questions, or to let me know your results.



One of the unfortunate truths about the 1st generation Rx-7 is, that the steering leaves something to be desired. While most import and many small domestic cars of the time were equipped with rack-and-pinion steering systems, Mazda's bean-counters insisted that as many parts from the corporate "parts bin" as possible, be used to get the new model out the door. The steering gear is essentially the same unit used in Mazda B-Series and Ford Courier pickup models of the time. The result, is steering that even when in top working order) is vague and VERY slow. With a ratio of 18.5 to 1 compared to a ratio of 15.8 to 1 for 84-85 power steering cars (compare that to about 15 to 1 for many R&P cars of the time) and the large 15 in. steering wheel used to accommodate small female drivers; "Can you say, "school bus??" A 13.5 inch steering wheel and adapter from Barry Grant (or MOMO if you're rich) will improve this somewhat. Summit Racing can hook you up with the Grant parts for about $60.

Like any mechanical device, the Rx-7 recirculating ball (RB) steering gear is subject to wear. As such, that vague sensation is amplified to a point that becomes downright numb. When I first purchased my `84 GS, I referred to the system as "wonder steering," as in, "I wonder where it's going next." Having had experience with RB units from Ford and GM cars and trucks, I made the usual adjustment to the sector shaft preload, to remove the excess play. This improved feeling lasted about 3 days and then right back to "wonder steering." The reason, as it turns out, is fairly simple. Unfortunately, not as simple to correct.

Tools Needed

To make the needed adjustments, you'll need the following tools. All are easy to come by.

40 mm or 1 9/16 in. socket (a six point socket works better). I bought one at Sears with a ¾ to ½ in. adapter for about $17. The open end of the socket MUST be ground down to completely remove the chamfer in the opening. I'll explain later. This takes about 5 minutes on a bench grinder.

14 mm socket and combination wrench, one or two long extensions and long-handled ratchet

A ½ in breaker bar, one or two long extensions and a length of pipe for a cheater bar.

A ½ in. wide cold chisel and ball peen hammer and a deep socket that fits snugly over the chisel shank will be needed with an extension.

A 0 - 1 inch dial indicator and stand. I bought an excellent dial indicator and magnetic base from J&L Tools for about $35 and it comes in handy for many other things as well.

How it works

There are three individual adjustments on all 81 ½ to 85 models with manual steering. 79-81 ½ models have only two adjustments. I'll cover what you need to know about each as we go. The order in which these adjustments are made is VITAL. Doing it wrong will result in no improvement at all and possibly irreparable damage on the later units. But first, some basics.

The steering wheel and shaft are connected to the worm gear. Think of this as a coarse threaded bolt, held in place by two tapered roller bearings. Mounted on this is the ball nut, which rides on a couple dozen small steel ***** that ride in the threads of the worm gear and ball nut. This is nothing more than a regular nut that has threads cut on both the inside and outside. As the wheel is turned, the ***** are rotated through the threads of the worm and nut and a small tube on the outside of the nut. Thus the term, "recirculating ball." As the worm is turned (no pun intended), the ball nut will move up or down on the worm gear.

The sector shaft is mounted vertically through the housing. The teeth on the sector shaft mesh with the threads on the outside of the ball nut. As the ball nut moves up and down the worm gear, the sector shaft will rotate accordingly. This motion is transferred to the pitman arm and then into the steering linkage. For the steering gear to work as intended, all of these parts must maintain some very precise clearances. When the clearances become excessive, the steering will become vague, with an excessive amount of freeplay in the wheel when centered, AKA "wonder steering".

The Fix(es)

I must stop and point out, that the balance of this article assumes that you have checked and verified that your ball joints, tie rods, idler arm, pitman arm and wheel bearings are all in good condition and properly adjusted. If not, you'll be wasting your time trying to adjust the play out of the steering. Once the items above are all verified, proceed. For those of you with power steering, or using a power gear with no pump, I'll provide a short entry later, since much of this will not apply to you.

Ideally, all of the adjustments that follow should be made with the steering box on the bench. However, being the lazy sort that I am, I found a way to do this in the car. Those of you with AC will thank me many times over, since pulling the steering gear is a pain in the butt on non-AC cars and downright unpleasant on AC cars.

1.

Make sure the steering gear is filled with 75W90 gear lube. With the front end lifted and on stands (please use stands), make sure the column lock is engaged to prevent the steering shaft from turning and disconnect the center link from the pitman arm. You need to do this to get accurate results.

2.

Mount a dial indicator and place the tip on the side of the pitman arm ball socket and set to zero. Gently move the pitman arm and read the indicator. If more than .001 in. play is present, you need to proceed. This is most of the free play you feel in the wheel. Note I said most.

3.

On all 81 ½ to 85 manual gears, there are two separate adjustments on the sector shaft. The large 40 mm nut and adjusting plug, sets the preload on the sector shaft bearing. The 14mm nut and adjusting screw is used to set the sector shaft and ball nut mesh clearance (This is the only sector adjustment on 79 - 81 ½ cars.). The 14 mm nut is covered by a metal cap from the factory. Pop the cap off with a pair of pliers and throw it in the neighbor's front yard. Loosen the 14 mm nut, then snug it in place for now. Loosen the 40 mm nut. This requires that you maintain a very straight alignment on the nut since it's very thin. If you round it off, you're screwed. Thus the need to grind the chamfer out of the socket opening. Remove the nut and turn it upside down. The bottom side has square corners and is easier to grip in the future. Turn the large adjusting plug counter clockwise ½ turn.

4.

Reconnect the center link to the pitman arm temporarily. With the front wheels on the ground, note the large amount of free play in the steering wheel. Note also that there is very little effort needed to turn the wheel, since the preload on the worm shaft bearings is gone from wear and there is some axial play (end play). This is where much of the vague feeling comes from and why simply adjusting the sector shaft doesn't work.

5.

Loosen the worm shaft adjusting plug lock nut (where the column tube meets the gear box), with the hammer and chisel, by tapping counter clockwise, as viewed from the driver seat. This is tough to do since space is limited. I found that inserting the chisel in a socket, taping it in place and using an old extension really helps.

6.

Using a 12 in. crescent wrench, turn the worm shaft adjuster plug clockwise (from driver seat) just a tiny bit and check the steering wheel. Keep going in tiny steps until you begin to feel a slight resistance to turning the wheel. You have now restored preload to the worm bearings, so the worm shaft does not have any axial play. Tighten the lock nut with the hammer and chisel.

7.

Put the front end back up on stands and disconnect the center link again. For 79 - 81 ½ cars, go to step 8. For 81 ½ - 85 cars, tighten the large adjusting plug on the sector shaft, just until it starts to feel snug. Check the turning effort of the wheel. When it starts to feel a little tighter than just after the worm bearing adjustment, stop. Lightly tighten the 40 mm nut for the time being. You have now set sector shaft preload.

8.

Lock the steering column so the steering shaft cannot move. Recheck the free play in the pitman arm with the dial indicator. Turn the small adjusting screw counter clockwise ¼ turn and check free play again. If the free play is less, keep going until there is zero play. If free play is more, turn the adjusting screw ½ turn clockwise and recheck. Keep going until you have zero play. Hold the adjusting screw with a screwdriver and tighten the 14 mm nut lightly with an open end wrench. Rotate the steering wheel 1 full turn each way, re-center the wheel and recheck the pitman arm play. If OK proceed. If not, repeat step 8.

9.

Reconnect the pitman arm and center link, install a new cotter pin and put the front end on the ground. Gently move the steering wheel left and right and watch the left front tire. If you did it as instructed, the tire will move with even the slightest movement of the steering wheel. If so, great, you're done. If not, go back and check your adjustments. I can assure you, if you followed this procedure exactly, you'll be right on the money.

10.

Tighten the 40 mm nut snugly. Don't over do it. Tighten the 14 mm nut to about 20 lb. ft. Test drive and be amazed at how much better your steering feels. You may need to tweak the fine adjusting screw slightly after a few miles and everything takes a set. This you can do by feel.

Power Steering

For those of you with power steering boxes, the sector shaft adjustment works like the 79 - 81 ½ cars. There is a worm shaft preload adjustment, but it requires that the gear be pulled from the car and partially disassembled. I have never done a Mazda power gear, but they work much like the Ford XR-70 unit. If you simply cannot get good steering feel with the sector shaft adjustment, take the gear to a pro and let him do it. I know when I'm over my head and it's worth the money to get it right the first time. A new power gear costs in excess of $1200. Certainly not in my budget.

Happy rotoring.

Bobrx7
Old 06-18-07, 12:23 AM
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By the way, that's the edited version. The original came from the Facts section on Mazspeed. It was very hard to understand because Bob used a messed up character set that didn't translate well from his keyboard to the internet. I went through it carefully and attempted to correct all the funky characters and replace them with correct ones (½, ¾ etc). I used the context of the sentences as a guide.

There are no guarantees that I got it right, so just keep that in mind and good luck fixing your steering!
Old 06-18-07, 11:23 AM
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Thats great. Thanks. Now maybe I can keep it in my lane when I get on the road.
Old 06-18-07, 12:17 PM
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Me too. Oh, one more thing. Bob recommends a 40mm socket. I test fitted one and it was too small. I tried a 1 9/16 and it was too small. Then I tried a 1 5/8 and it was too big. Haven't tried a 41mm yet since I don't have access to one.

Has anyone here every bothered with their steering boxes and the large nut specifically? What size is it really? My car is an '83 for reference.
Old 06-18-07, 04:43 PM
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I dunno what size it is either. It looks like someone used a hammer/chisel on one of boxes I have looked at.
I have an '83, and cannot for the life of me, find the 14mm nut/adjusting screw. I can plainly see the large one, and the fill plug, but the smaller one mentioned above (and many other places) continues to elude me.
Old 06-18-07, 04:49 PM
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In the very center is a metal cap cover. I gripped mine with a vice grip and pulled upward. It came off easily. Turns out I didn't need to expend all that much effort on it.

So look for the metal cover in the center of the big nut, extending upward like a half inch or so. Pull it off and the 14mm nut and adjusting screw will be there.
Old 06-18-07, 04:58 PM
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Are you saying it is inside the center of the adjuster that's inside the ~40mm nut?
I'da never thought to look there.......
Old 06-18-07, 05:08 PM
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Yeah. It's a smooth sheet metal cap. Pull it off and you'll see.
Old 06-18-07, 05:09 PM
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Thanks. Every artical I have read mentions this adjuster, but fails to mention the location......... Somewhat important info, one would think.


Sure as hell. I went out and popped off that cap, and there it is, just like Jeff said.

Last edited by Rogue_Wulff; 06-18-07 at 05:17 PM.
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