Success in adjusting the manual steering box on an 84 Rx7 GSL
 

I had +1.5” of free-play on the steering wheel. Not really safe to drive at higher speeds. I was considering replacing the box & shaft but decided to try and adjust the original one first.

Special thanks to members here and to Bobrx-7 for posting on Mazspeed.com a procedure for adjusting the steering gear box with the box still in the car.

http://www.mazspeed.com/steeringgear.htm

I copied his post into Word, printed it, and then made notes to take to the garage.
I also printed pages 8-10 of the 85RX7(10A)manual_steering.pdf for the specs and diagrams.
The Haynes book was of not much use, but combining Bobrx-7’s text and the FSM I was able to understand what was what and the sequence of adjustments and by how much.

1. Tools
A. Some pounding of a punch and chisel is necessary. I went with 1/2” deep impact sockets and drive extensions, rather than the 3/8” drive sockets and extensions.
B. I decided to go with the FSM specs to set the worm shaft and sector shaft preloads. Using a fish scale has been mentioned on this forum. I tried a cheap spring scale of 0-50 lb, weighed a 4 lb bag of sugar and it read 2.4 lbs. At Dick’s Sporting Goods I found a 25lb digital scale ($20). For whatever reason I have a 500g weight from a beam scale and weighed it on the on the Rapala digital scale. It read 0.50kg. Close enough.
C. Bobrx-7 suggests using a 12” Crescent wrench to turn the worm shaft adjusting plug. The plug measured 1.81” and the largest gap crescent type wrench I could locate that had chance of fitting into the space available was 1.6”. I was able to adjust the plug with my old Vice Grips opened really wide.
D. As Bobrx-7 states you need a 40mm socket. I bought mine online for $23 from Sears (outrageous shipping charges however IMO). Prior to grinding down the open end to remove the chamfer, I tilted a flat file at about 45 degrees and spun the socket against the corner edge of the file to score a line parallel to the opening. I used this line as a guide during grinding. However the 40mm socket did not fit on the 40mm sector shaft locknut. The locknut measured 40.79mm and the socket opening was 40.59mm. Additional grinding with a small drum was necessary on all 6 sides to get the opening to 40.81mm.
E. All the other tools pictured I had on hand from prior projects.

Procedure – additional comments to the directions posted by Bobrx-7 (step numbers below correspond to Bobrx-7’s numbered steps). Follow his complete steps.

I had previously redone the front suspension: tie rods, ball joints, idler arm, wheel bearings adjusted, so I skipped the first check of the pitman arm free-play as I needed to get rid of the steering wheel free-play. To see what was what on the gear box, I cleaned off the 33+ years of gunk, with Gunk.

3a. Removed 14mm nut and lock washer from the sector shaft. Turned the sector shaft adjusting screw 1/2 turn clockwise.
3b. Removed the 40mm sector shaft locknut. Torque wrench was necessary & it popped loud.
3c. Marked one of the holes on the sector shaft adjusting plug and a corresponding “start mark” on the steering box. Used the center punch, socket+extensions, & hammer to rotate the plug counter-clockwise. I went over 270 degrees and it stopped so I turned it clockwise a bit. Steering wheel free-play was now over 4”.
5. Loosened the worm shaft adjusting plug lock nut with the chisel, deep socket+extensioins and hammer. There really is not much room with the break lines, oil cooler and assorted wires.
6. Using the Vice Grips I nudged the worm shaft adjusting plug clockwise and kept checking the preload at the steering wheel. Not having the “special tool” indicated in the FSM, I guessed the perpendicular arm of the tool at about 7-8” and used the fish scale to pull light and steady on the outside of one of the steering wheel spokes, while watching the readout. The FSM spec is 0.2 to 0.5 kg. My beginning preload was 0.02 kg. Image #6 shows how little I turned the plug to get the preload to 0.40 – 0.45 kg. I tried for the center value of the range to compensate for not having the special too and the box was still in the car. (The final preload check with the box in the car is only .02 to .05 lb above the preload with the box out of the car.) Tightened the locknut with the hammer+chisel combination.
7. Raised the car and disconnected the center link from the pitman arm. Tightened the sector shaft adjusting plug first back to the start mark and then more, about 45 degrees at a time and kept checking the preload at the steering wheel. I went a full 360 degrees clockwise from the start mark to achieve a 0.90 – 1.00 kg preload. The FSM spec is 0.6 – 1.2 kg. Installed and lightly tightened the 40mm locknut.
8. Locked the steering column. I could visibly see free play in the pitman arm. I kept turning the sector shaft adjusting screw counter-clockwise in small increments and checking the free-play on the dial indicator. Each space on my dial indicator is .001”. When I got the free-play to less than .0005” I stopped for now. Tighten the 14mm nut as instructed.
9. Reconnected the center link, tightened the 40mm locknut.

I now have less than 1/2” free-play as measured on the outside of the steering wheel. That, numb, vague feeling is gone. When I hit a bump with one wheel, the car no longer wants to self-steer.

It’s fun to drive again!!

Really, if I can do this, it can’t be that hard.

Nice write up. I can see the 1st 2 pics but the rest result in image could not be loaded. Seems like an
error on the website cause I don't see a big difference in the pics or their names.

Works here but I think the error is due to I made an edit in the image attachments.

Repost of ref. images.

Thanks for posting. Subbed for future reference.

Great write-up. I can see the all the pics no issues.

great write up.

so looks like the socket should have been 41mm.

Is there any way to adjust a power steering box?

This great. I wish the forum had +1 or upvote button.

When looking at the locknut flat hex-sides I noticed they were rough all the way around the middle but smoother toward the top & bottom. I have no idea how these were manufactured but measuring the nut prior to buying the socket may be prudent.

From Bobrx-7's post:

Power Steering
For those of you with power steering boxes, the sector shaft adjustment works like the 79 81 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.


I personally have no idea.

Got a video of the freeplay/driving at all? Sounds interesting

Sorry, don't have a GoPro & my DSLR does not have image stabilization.

After driving this week and things have settled a bit, I have about 5/8 - 3/4" free-play. I still have some adjustment left on the sector shaft adjusting screw. Robrx-& said this might happen.

That's a great writeup! I've read those references a bunch lately.

At the risk of hijacking Tim's thread, does anyone know the part numbers for the seals inside the steering gearbox? Mine is leaking badly, and I have not had any luck finding an aftermarket seal kit except for one which is "universal", or rebuild kits, or part numbers to take to a dealer...

https://cimg6.ibsrv.net/gimg/www.rx7...1724fc00ed.jpg

Can anyone identify and tell me how many points of adjustment I have on this steering box? I believe it is a series 2 box retrofitted to my s3 (Aus spec) for the higher speed (less turns)
As far as i can tell it only has one adjustment - the top screw.
Been playing around with it just now - with the front jacked up just enough to take some weight off the tires but still provide some resistance - screwing it in definitely tightens up the slop. Screwing it all the way in makes the steering wheel heavier to turn.
I'm thinking to adjust it all the way in, and then back it out until the wheel becomes "light" again.
Can someone please correct me before i fuck this up lol.

Anyway that worked. Went for a drive... bloody marvellous. The simple things in life, eh? Like, not having to saw the wheel to go straight lol.
BTW that chewed out sector shaft screw is not the result of some kind of ham-fistery involving hammers or violence - it was touching the turbine housing on dicky engine mounts in a previous incarnation (not my doing) and got tapped flat on one corner.

https://free-info-pages.com/rx7-steering-box-adjustment.htm
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The above link shows a picture of the 3 adjustment points for later boxes. Your box only has #1 and #3. You will want to adjust both to ensure you don't wear your box out prematurely.

Steering Gear Restoration - Mazspeed
You will want to go to this page and follow their instruction as best you can, make sure you also check your tie rods and idler arm for being loose, and check your alignment. Too much toe in can feel like a really sloppy steering box.

Edit: Never mind, then. Looking closely at your picture, it is missing the adjustment nut for #3. I would still suggest checking your alignment.

Thanks Joe. Great link. It does appear i have only the one adjustment then!?
Alignment and the rest of the steering system are pretty good. Simply adjusting the one adjustment available on mine made an enormous improvement, but a bit worried it could be harmful to the longevity of the box. I will do some more reading when I get a chance.

Hey I know this thread has been dead for a minute but I was wondering if they were talking a about having 1/2” play in the steering shaft or the steering wheel I’m assuming steering shaft but if they are talking about the wheel then I need to get on that

+1.

It's 1/2 inch play in the wheel.

1+ on this thread.

Thanks Tim.

YW.
Yes I had 1 1/2" free play on the steering wheel. Its still about 1/2" inch after the adjustments. Lots more fun to drive.

Overadjusted?
 

I followed your instructions as close as I could and now have almost zero play. I do have some return on the steering but feel it's just a bit too tight. Easiest way to back a little off or do I need to go through the whole preload process again? Thanks

It has been some time since I did this. Yes, mine does not return as easily as I would like. If seemed better before new crappy tires on the front.
I'm suspecting the preload is too high, but I don't know for sure.

One thing I think I remember was you do need some free play so you don't prematurely wear out the box. I hope someone with more knowledge will jump in and correct me.