How to improve an MR2 Turbo’s steering with an MR2 Spyder pinion | Project Toyota MR2 Turbo

J.G.
Update by J.G. Pasterjak to the Toyota MR2 Turbo project car
Jul 13, 2021

While we love our MR2 Turbo’s handling, especially now that it has a proper suspension in place, we can’t exactly say the same thing about the steering.

Even with the optional electro-hydraulic power steering system—which our 1991 Toyota MR2 Turbo has—the steering is painfully slow, requiring almost 1200 degrees of rotation (more than three full turns) to get from lock to lock.

This means arduous slaloms and transitions on the autocross course, along with needless hand repositioning on road courses in tighter corners. In our best late-night infomercial voice, we would look toward the heavens after each track session and scream, “There’s gotta be a better way!”


Thankfully, there is, and it’s as close as family. The Toyota MR2 family, as a matter of fact.

See, the steering pinion from the power steering rack of the more modern Toyota MR2 Spyder directly fits into the SW20’s rack. The gear pitch is identical, and the seals and fastening threads all line up. The only difference is that the Spyder pinion has seven teeth while the SW20 MR2 piece has six.

[MR2 Spyder buyer's guide]

So, right away, you see the advantage. That extra tooth means 15% more movement of the rack for a given movement of the pinion, which means less movement of your hands. Good news all around.

The question then becomes where to acquire one of these magical pinions, and the best route we’ve found is buying a complete rebuilt rack on eBay. Individual pinions also come up for sale on various MR2 boards and social media sites, but the prices tend to be about the same as a whole rack.

So if you’re not in a hurry and you want to support the MR2 community, hit up social media. If you need something right away, maybe go the rebuilt rack route.

But be careful: We actually received the wrong rack from one rebuilder and didn’t realize until it was too late. We ended up sourcing our pinion from another MR2 owner, and luckily the seller of the rack agreed to take back the incorrect part after we had disassembled it.

If you want a good look at an actual MR2 Spyder power rack, check out Mike Reed’s page on removing the pinion. The most consistent way to identify the MR2 Spyder rack seems to be those two hydraulic connections coming out of the same side of the rack. Many other Toyota racks clock those almost 180 degrees apart. So check with the seller of any rebuilt rack in advance to try to visually confirm you’re getting the right one.

Once you have the rack in hand, replacing the pinion is a fairly simple afternoon project. The most difficult parts are likely to stem from the age of the car and any corrosion present on key fasteners. Here’s a quick rundown of the play-by-play:

1. Disconnect your tie rod ends at the knuckles. You’ll want to mark them to make sure the length doesn’t change, but you’ll need a proper alignment after this is over anyway.

2. Remove the U-joint from the top of the pinion, located under a cover in the frunk. You’ll want to undo the bottom-most fastener in this photo and remove it, allowing the pinion to slide out of the U-joint.

3. Drain the rack by removing this hydraulic line, which is under the car at the back of the rack. By the way, during this process, power steering fluid will get everywhere. Coat every surface within a 100-yard radius with towels, and wear clothing you never need to wear again.

4. This slightly out-of-focus 19mm fastener retaining the banjo bolt will also have to be removed, though it looks harder to access than it really is. With the right combination of extensions, you'll have a fairly straight shot at it from the wheel well. Just make sure to retain any washers and be mindful of more spurting fluid during this phase.

5. With the hydraulics now disconnected, remove the rack from the car. Unbolt the two retaining clamps—we treated ours to a media blast and powder coat while they were out of the car—and the rack should wiggle free without much drama. You may need to coax the pinion out of the U-joint a bit up top.

6. Now that the rack is on the bench, you can remove the hydraulic lines from the retaining tower of the pinion. You 100% need to use flare nut wrenches here, as these fasteners are likely a dangerous combination of very tight, very soft and rusty. Rounding off one is absolutely on the menu if you don’t use proper tools.

7. The pinion is retained by the fasteners in two areas: the ones holding the pinion tower to the top of the rack, and the threaded one attached directly to the pinion at the bottom. Remove the cover for that fastener, then remove the nut on the bottom of the pinion, and it should slide right out with a little twist as you disengage the gears. This is also a great time to drain the remainder of the old fluid by working the rack back and forth and shooting power steering sauce all over your garage.

8. And here’s what you’re left with: The seven-tooth Spyder gear is on the left—the fella we bought it from had replaced the O-rings with fresh seals before we got it—and the original six-tooth SW20 pinion is on the right. Hooray for mechanical advantage.

Assembly is the reverse of removal, as they say in the shop manual world. The pinion will drop right into the rack with a slight twist—make sure the rack hasn’t rotated and the gear teeth are properly oriented. All of the mechanical and hydraulic connections are the same as your original rack, because this is your original rack.

Replacing the U-joint onto the pinion is easier with an assistant, but a few trial-and-error moves will work out, too, if you’re a lone-wolf renegade.

Once the rack is back in, you’ll need to bleed the air out of the hydraulic system. Fill the reservoir with a Toyota-compatible synthetic power steering fluid (we used Lubegard), and work the wheel from lock to lock a couple times.

Check the fluid level, top it off, then start the car and run the wheel from lock to lock again, pausing at each lock with a bit of pressure on the wheel for a few seconds. Repeat this for a couple minutes while frequently checking the reservoir and filling if necessary.

Finally, get a proper alignment—there’s a 100% chance your steering wheel is now off-center—and head to the track.

We spent the day after our first autocross with the new pinion cleaning cone marks off the front fenders. We were clobbering them with the inside of the car because our MR2 actually turned with some authority.

Remember, this mod only works on power steering-equipped SW20s, and only the power steering pinion from the Spyder will fit. Rebuilt Spyder racks go for $160 to $200 on eBay or from various rebuilders. If you find one in a junkyard, you’re luckier than most. If you do ever see a power steering-equipped Spyder at a pick-and-pull, grab the rack.

In the meantime, we’ll be enjoying a great-handling sports car that now has vastly improved steering as well.

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Comments
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Number1Gaza
Number1Gaza GRM+ Memberand Reader
7/12/21 7:42 p.m.

Given how squirrelly SW20's are from the factory, this would seem to be a nice way for a driver to be able to catch the back end faster.  Among other advantages.  

stylngle2003
stylngle2003 GRM+ Memberand Reader
7/13/21 12:16 p.m.

You can do this same swap with an Integra pinion into many civics.

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