Converting NA Miata to manual steering. Gotchas?

Been told that I will need new tie rod ends if and when I install my recently acquired manual rack.  I am struggling to see how  and/or why the parts would be different between the manual and powered applications. Anyone shed any light on this?

Pete

I've always heard the r-package tie rods help alleviate bump steer, no idea if there's any truth to it. Honestly seems more like one of those "while you're in there" upgrades

Yeah, I think it's more one of those "while you're in there" things.   I did mine last year and replaced both the inner and outer tie rods.  The R package outers help with bump steer if your car is lowered a small amount, but if it's really lowered to race height it's a better solution to shim the steering rack (if permitted by race class).  At a minimum you'll need the little steel washers that connect the inner rods to the rack, those get destroyed when you take the old ones off.  IMO if you do it you should do it right- some people just loop the lines but it makes the steering heavy and clumsy.  The right way is to take the whole rack apart and cut out the seals.  It's also good to weld the pinion while you're in there, it improves the steering feel.  Lots of Youtube videos on the subject.  Overall it's a tedious job but not a very hard one.

EDIT- I just re-read the OP and saw that you found a manual rack already.  Disregard my comments about depowering the old one.

Don't ask me why, but the NA manual rack has different threads on the tie rods than the power rack.

(update with clarity: the threads on the ends of the rack where the inner tie rods attach are different)

In reply to Keith Tanner :

Are they like the RX7s of that era where the manual steering cars had different inner tie rods, tie rod boots, rack bushings and rack brackets? One of the reasons I went depowered on my RX7 is because the bushings and brackets are NLA for manual racks. Even the tie rods and boots are getting hard to find. I'm guessing Mazda made a lot more Miatas with manual steering than RX7s so maybe it isn't an issue.

I just looked up the parts fiche. The inner tie rods are different, but the outers have the same part number. Manual parts seem to have an NA01 prefix, power parts have NA02. Boots are different (smaller housing diameter), bushings are different (you can get replacements from SuperPro, guess where you can buy those!), inner tie rods are different, brackets are different and the manual ones are NLA.

Keith Tanner said:

Don't ask me why, but the NA manual rack has different threads on the tie rods than the power rack.

Hrmmm, that's good information. I have a set of r-package tie rods I've been meaning to install on my power steering '95...dunno if that's a viable plan

It's the inner thread. Outer tie rods are the same. Basically, match the inner tie rods to the rack and you're good to go.

Had I stopped to think about this for a moment, it would have been painfully obvious because we've been putting those R package outer tie rods on PS cars for years and years.

Argh...why cant anything be simple!

So, I could have used the same outer tie rod ends?

But the one torn boot can not be replaced with the  good ones from the current depowered rack? Better order one of those.

What "bracket" is NLA?

Thanks all for helping me with this stuff.

Pete

The "bracket" that holds the rack to the subframe on the passenger side. I'm pretty sure you have the capability to overcome this problem, and of course any Miata that can donate a manual rack has one of those brackets :)

In reply to Keith Tanner :

I am in luck then as it cam with both of the metal brackets on the rack. That was a close call! 

I hope this goes far enough in making  parking lot maneuvers easier.  If it does not, next stop is to find a power rack and do the Volvo electric power steering pump. 

My first Miata had the manual rack. It was good for driving around, tolerable in parking lots with stockish wheels/tires.  Wider/stickier tires made it a PITA.

In reply to NOHOME :

Is this for the Molvo? If so, what's in it now and why do you need to source another power rack? Doesn't it have a power rack currently?

In reply to DeadSkunk (Warren) :

It has a properly de-powered rack  and 200 tw tires that is a bit more than I want to deal with. Really cant toss the car around a corner unless you  are putting some effort into it.

The manual rack is a Hail Mary pass before I go all the way back to a power steering rack powered by a Volvo electric power steering pump.  I have validated the Volvo pump system with the F2 truck and it seems to work pretty good and it is easy to install compared to the electric assist that involve the steering column. The downside is that it  might be fine for the F2 but too much for the Molvo. 

Pete

In reply to NOHOME :

Are you talking about the pump unit used in some of the S40s?  That is the same unit, IIRC, that is used in the Mazda 3/Mazdaspeed3.  I haven't heard of the pump being insufficient for power assist on an overpowered, grippy-tired front driver, but I also haven't really been looking either.

I had a manual rack on the Exocet and it felt so, so slow. Much easier to turn than the depowered rack, but just terrible on track. I didn't realize how bad it was until I drove my full body miata on track with the exocet back-to-back and realized why the turn-in felt so slow.

Pete. (l33t FS) said:

In reply to NOHOME :

Are you talking about the pump unit used in some of the S40s?  That is the same unit, IIRC, that is used in the Mazda 3/Mazdaspeed3.  I haven't heard of the pump being insufficient for power assist on an overpowered, grippy-tired front driver, but I also haven't really been looking either.

They are very similar if not the same. The only thing is I have found no information on the wiring of the Mazda unit and have heard the Mazda pump might be CAN bus technology vs analog for the Volvo pump. The Volvo pump needs battery power and a 12 volt "key on" signal to fire up the pump. I have the 12 volt signal wired through a NC relay so that it will not turn on the pump while cranking the engine. 

If the Mazda part is a direct replacement it would be great.

Not worried about it being insuficient, more worried about it ending up with the steering feel of a 70s American barge. Seems to do the job in the Ford F2 with a Mustang rack. The truck is weird to drive because stock, it is a hand-over-hand thing to go around a street corner. This thing just go-karts around the turns. 

As to the manual rack being too slow, I have had comments of "It is a bit twitchy" the way it drives now.

If the Mazda pump requires a CAN signal, I may have some of the information we need to make that work. I certainly have the hardware. But more likely that's to adjust assist level, and without the CAN control it'll just run full throttle like the Volvo unit.

If the car is twitchy, I'd be looking at alignment first. Slowering the steering would be a fair way down the list. The NA manual rack is not the finest piece of engineering in the Miata, it was thrown together in six weeks to appease the "OMG YOU CAN'T HAVE PS IN A SPORTS CAR" weirdos.

In reply to NOHOME :

One of the major problems was trouble saving the car from spins, a lot more angle to get it out of trouble and way faster hands, but I only run the Exocet on road courses, not much autoX or anything.

Though you'll know if you like it or not since you ran back to back with a power rack. The manual rack is SO much easier to turn at low speeds - no difference in effort at speed for my use case.

In reply to NOHOME :

Steering feel is going to be due to the valving in the rack, not the pump.  The pump just sends fluid through the spool valve in the rack, steering loads send fluid to the ram lines, which is where the restriction will occur that causes pressure buildup.

People DO put pressure bypass valves in pumps to change feel, but that isn't really the right way to do it.  It's a lot easier than messing with the torsion bar in the spool valve.