Depowering a Miata Steering Rack

I'm getting ready to set up another 96 Miata for track duty. On my last car (now sold), I did it the quick and easy way by draining the fluid and looping the lines around. I was happy with the way it came out.

Now I see that there is a more complicated method that's supposed to decrease resistance on the FM website. Has anybody done it this way and can it be done with the rack in the car?

I've done it :) I don't think you'd save any effort by doing it with the rack in the car, as you have to pull the pinion. That means disconnecting the steering column - and at that point, you're only four bolts away from having the rack out.

Warning, I think the 1996 racks come apart differently than the earlier one I used to do that writeup. Check the FSM.

I depowered the steering rack in the former Challenge Miata (and the Tracer too) following the FM guidelines, it feels nearly the same as a stock manual rack, but with a shorter ratio and works quite well with stock steering wheel diameter.

Removing the steering rack from the car is a breeze and will make the depowering process much easier. Disconnect the steering column input from the pinion via a single bolt, disconnect the tie rods, and remove the 4 nuts securing the rack to the subframe. It'll slide out the side through the wheel well.

What do you really gain by doing this? As I mentioned, I didn't really think there was anything wrong with the last one I did the easy way.

Also, I've also remember hearing about swapping to R-model tie rod ends. Is that to help with bump steer?

Less internal friction, you're removing a seal that's no longer needed.

The idea behind the R-package tie rods is to cut down on bump steer if the car is lowered.

Keith wrote: Less internal friction, you're removing a seal that's no longer needed. The idea behind the R-package tie rods is to cut down on bump steer if the car is lowered.

How low do you need to go before you need them? Suppose for example, I were to use, oh I don't know, say, Flyin Miata springs?

There are thousands of happy Miata drivers running around on FM springs and stock tie rod ends :) In fact, most 1990-93 models are at that ride height right now on stock springs.

I've never actually measured bump steer on a Miata, so I can't quantify exactly when they become superior to the stock ones. The R package sat about 13" front and rear, which is where the FM springs will end up.

What is every body's thoughts on welding up the slop in the pinion shaft like described here: http://www.motoiq.com/magazine_articles/id/1709/project-miatabusa-part-5--de-powering-the-steering-rack.aspx

I would have to MIG mine (I don't know how to make purdy TIG welds like the guide ).

We're doing one right now. It's the first time we've tried it. The theory seems good.

believe i emailed you about this last week keith

Did it on my track Miata.........it's fantastic. Below 5mph with lots of caster it's a bit tough, but once moving, no big deal.

On track at speed, the feel is amazing. I've never felt so comfortable with a car getting so sideways and being able to easily/quickly catch it.

Keith wrote: There are thousands of happy Miata drivers running around on FM springs and stock tie rod ends :) In fact, most 1990-93 models are at that ride height right now on stock springs. I've never actually measured bump steer on a Miata, so I can't quantify exactly when they become superior to the stock ones. The R package sat about 13" front and rear, which is where the FM springs will end up.

I was about to ask you about this, then realized I'm running my car over 1" lower than that. I haven't noticed a big issue with bumpsteer even pounding curbs and such.

Are you going to MIG or TIG? How are you going to clean all of the power steering fluid out of all the nooks and crannies of the pinion? Thanks.

In reply to bgkast:

Brake Kleen is a no-no (at least the chlorinated kind). I soaked mine in gasoline, let it air dry a while, then burned out the rest with a propane torch. Didn't get hot enough to worry about the metal, just enough to get any excess oil and gas out. The welder TIGed it for me and it worked awesome.

In reply to bgkast:

I de-powered the rack on my former '89 RX7 with this same method but did not get the pinion welded up. Although I was very pleased with the de-powered rack, up to the day I sold the car I wished that I had done the weld-up. The steering feel was very good and the effort in the realm of tolerable, but I always felt that there was a little bit of "rebound-y" feeling on initial input from the pinion slop. A little bit in steady-state cornering as well if the surface was at all uneven. If I ever do it again I'll have the pinion welded.

I'm going to attempt to MIG mine up this weekend. I'll post some pictures if it turns out ok.

bringing this back up to ask a question. For those that have welded the pinion, did you remove that other bearing first?

the one still on the shaft up against the teeth in this photo:

also, that MotoIQ article specifies "Weld Mold 880" filler. anyone use this? any other appropriate alternatives?

this weekend I pulled apart one of my Impulse racks while I have the engine out, turns out it is a JKC unit and the pinion assembly is pretty much identical to the Miata parts pictured.

I can't get that other bearing off though, there is some rust/crud around the shaft. would it get damaged by the weld heat or should I spend the time to clean it up and press it off?

We used whatever wire was in the MIG when we welded my pinion. Just a couple of spot welds around the circumference.

I've heard that you can end up with tight and loose spots in the steering if you overheat the pinion and it bends. Having said that though and looking at the picture again, I don't know how that would happen.

I knocked off all the bearings before we welded mine. I had a stuck bearing and was starting to fret about how to get it off when my buddy walked over and simply tapped the damn thing on a hard surface a few times. (Hold the pinion vertically, smack the end on the anvil part of a vice, or what have you) The bearing literally just fell off. It was one of those times I was reminded how little I actually know about this hobby

bgkast wrote: What is every body's thoughts on welding up the slop in the pinion shaft like described here: http://www.motoiq.com/magazine_articles/id/1709/project-miatabusa-part-5--de-powering-the-steering-rack.aspx

The FC rack is just about the same as the Miata rack (possibly identical internally) save for the width.

I've been rallycrossing a Q&D depowered rack since 2010. (Run the fluid out, plug the ports, then cut the two ram lines and loop them together with a piece of fuel hose) If it has more friction than a de-pistoned rack then I can't tell, and there's no play in the quill.

http://www.rx7club.com/2nd-generation-specific-1986-1992-17/anyone-had-looped-ps-rack-break-quill-1015943/

I wish I knew about this when I was having PS issues on the 318ti

I got new bearings from McMaster-Carr when I did my Miata rack. The stock bearing was (I think) 7mm width, and the closest one McMaster-Carr had was 8mm. It worked fine. fairly cheap too. You may want to check them out.

bgkast wrote: I'm going to attempt to MIG mine up this weekend. I'll post some pictures if it turns out ok.

Whoops, looks like I forgot to take pictures before I put it back together. The MIG welding went Fine. I put the smallest of nicks on the rack when I cut the seal off, but I don't think it will matter. To plug the old hydraulic ports I cut the hoses short and used jb weld to plug the short hose bits, then reinstated them with the original nuts.

Just by a Miata with no power steering. That's what I did!

RossD wrote: Just by a Miata with no power steering. That's what I did!

Those have a slower ratio though, correct?