Something is loose in my steering shaft. But what?
 

Hi,

When I turn the steering wheel slightly on each side, there's a pretty big dead zone (more than it should be). It looks like the pin is too small or something. Can you guys tell me what's the problem there?

The pin looks OK, almost looks like the hole the pin is in is hogged out.

May have to find another steering column. Not sure if they are RHD/LHD specific. It's really not too bad to pull the column all things considered.

Dale

It's been discussed on here previously.

Steering shaft is hollow, the pin where it goes through the universal joint ovalises it over time. Probably very common on these cars, of the several second-hand steering shafts I had, majority of them had wear to a greater or lesser degree. There's not just a dead zone in the straight ahead either, roads with a crown can make for excitement at speed!

No need to remove the steering column either, just two bolts to remove...and one to loosen - all in the engine bay, looks like you need a bit of heat shielding though.

Engine is out at the moment so that's why there is not shielding! I wonder if it is available at the dealership?

Just going to the condition of the boot, top one usually doesn't deteriorate like that unless exposed to heat.

People have bought them here recently after burning up the lower uni boot with single turbo conversions so I'd expect yes, they are available readily.

Assuming that's an early 90s import, you should be able to check rhd v lhd #s easy enough

https://mazda.epcdata.ru/rx-7/

Sorry for very late response - been busy working on a ship since 2 years. I wonder if I could send the column to a machine shop and maybe they could drill the hole bigger, and build a pin for it. My car is RHD so it could be a very interesting solution.

That would be a good idea. Or you can punch the pin out and replace it with a nut and bolt

I think Carroll Smith used to describe a nut and bolt used in this application, as a crime against nature, but I've seen recent Mygale F4s done that way! His recommendation was one of these -https://www.aircraftspruce.com/catal...86taperpin.php with the hole reamed to size.

New replacement cost, at least in this neck of the woods, certainly makes you want to seek an alternative, ha.

Well I've been thinking about it instead of sleeping last night: why I could not simply weld the whole hole together, to make one solid piece? I think it would be a permament and reliable fix, what did I forget?

Damn, if that's the case then don't make it rigid. The odds of that scenario happening are extremely slim but if you were to get in a crash then don't let this be the one thing that takes you out

Yeah, not so sure on that. Mazda lists the column itself as collapsing in the parts catalog and manual. IMO it would have been very poor engineering practice to place a shear pin in an application where A) it is absolutely necessary to maintain control of the vehicle and B) where it is subjected to shear force on a regular basis

A better and more reliable solution is a collapsible shaft, which I believe they probably used.

I would go with the Carrol Smith solution as it seems to be a great option if a bit involved (decent machine shop shouldn't have a problem doing this). I believe the use of a regular nut and bolt would be frowned upon because the fit between the pin and parts should be interference to eliminate any slop and subsequent wear. A regular nut & bolt is usually deployed with a clearance fit. The F4 cars may use a shoulder bolt with a tight fit.

Okay it's a safety feature, it makes sense!

And how am I supposed to choose between all the pins proposed on the website... I hate choices!

I would just track down a good used part. This isn't a common problem and I think you should be able to find a good used one cheaply.

This is definitely something you don't want to experiment with. Steering failure is no joke.

Dale

You'd have to drill out the pin, measure the diameters of the holes, then go nearest size in the pin (oversize!). Looking at the aircraft spruce site, the dimension table appears incomplete too.

Secondhand might be the easiest as Dale mentioned, if you don't have reamers or a machinist with appropriate ones to hand. As said previously, most of the ones I have are worn.....although none as bad as that. Lots of people get used to worn-out parts too if it happens over an extended period of time, so good chance what they think is a good part is, or heading towards, being a POS......of course if Mazda just used a solid shaft in the first place rather than try to shave a few grammes we wouldn't be having this discussion at all!!

Engineers always over-complicate things lol

Good point. My car has 155k on the chassis and no play whatsoever on completely stock steering rack, u-joints and bushings. The only problem I've ever had was a little play in the inner tie rod ends.

I already searched for it, without success. I don't think it's gonna be that easy to find that part, my car is a RHD... LHD probably won't fit.

What about this one? It's even in BC (geography is hard for US residents so I don't know how close that actually is to you).

Cheapest new F100-32-090A before freight/tax whatever, appears to be around @$270 CAD. Over here, I'd be inclined to try for a S8 shaft, for mileage purposes.
https://cimg5.ibsrv.net/gimg/www.rx7...cda8c3ea33.jpg
https://cimg5.ibsrv.net/gimg/www.rx7...36e59e0622.jpg
pin
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Looking at one yesterday, pin appears to be around 8mm diameter. I'd guess sleeving both the shaft and the pin bore might be another way....a bit tricky to hold something like this to machine!

I've got no clue how you found that. I just searched on ebay.com and ebay.ca "rx-7 1993 steering shaft" and "fd3s steering shaft", without success. It seems to be pretty worn though. Could be worth a try, I'll PM the seller. Thanks!

Like DaleClark said, I don't want to experiment things with the steering shaft. I already had a steering shaft failure on a Buick LeSabre 1994 and it really scared me.

270$ CAD, you mean on RHDJapan? That's the only place I can find the part... LHD won't fit?

I also found that on eBay, a FC3S coupler. It really seemed like it is the same part... https://www.ebay.com/itm/1989-1991-M...r/192704470425

Dunno about LH, must have a different part number, as there's no strikes of the usual US vendors using that one - suspect the length might be marginally longer RH?

One I saw was on amazon jp.

I'd probably look on yahoo if no late stuff around locally, "only" 18 years old max if going for this century production. :) Wouldn't be surprised the unis would be pretty similar between FC and FD, that looks like the one at the pinion end rather than the intermediate. The problem starts in the inner shaft though....which will still be flogged out, even if you could source an appropriate joint/pin

Thanks a lot for all the help you provided. I will probably buy the used shaft that alexdimen pointed out, it will be easier that way.

:scratch: sometimes google is better at searching ebay than ebay?