GR Yaris JDM RZ High Performance

[sixtentouge]

Hello Zoo. American who grew up in Japan, I started in KP61 Starlets when I was 18. Have had more than I can remember, in all configurations. NA, turbo, engine swapped, you name it. All built for winding road, gymkhana, etc.

So after fifty-odd laps around the sun, all three kids done with uni, and wife comfortable in her Lexus, she says, "Why don't you buy a car for you?" LOL.

Thought long and hard about grabbing another KP and turning it into a touge monster. Maybe a 2GR swap. But I also thought long and hard about dealing with rust every couple of years, carrying a tool box with me wherever I go... And then there are all my long-time friends my age who have a project car that's in a perpetual state of upgrade/repair, being driven one day per year...and so on.

I decided I want a car to drive, and not a car that sits in the garage being worked on. GR Yaris, being the successor to the Starlet (Starlet>Vitz>Yaris), Toyota's smallest performance hatch looked to be the go. You can buy an RC and trick it out with everything to make a serious gymkhana car for around the same price as the RZ High Performance, but the RZHP looked to check all the boxes for I want to do, with all stock parts.

My oldest son is a master tech and inspector for a larger Toyota dealer chain here, so I was able to take their demo RZHP to wring it out a little bit, and I was sold (and given a substantial discount). A year and three months later (3/23) it arrived.

Other than some parts from the GR Parts catalog I ordered separate (cheaper that way), an idle-stop canceler, and MFF flaps, it's bog stock. Reading stuff on forums, I jumped the gun and ordered an oil cooler from HEL, but haven't installed it, as it doesn't get hot enough driving winding at six-tenths.

The car is excellent, and hits every mark. The only thing I want to improve is a little snap body roll on hard corner-to-corner transitions. Maybe Ohlins or KW is on the radar. We'll see. Doesn't need more power, nor more tire for what I do. JDM speed limiter is set to 190km/h. Easily defeatable, but again...don't get anywhere near that in the tight twisties, so I'll leave it alone.

I name special cars, and this one's "White Trash Beautiful"

A few pics of the car and last weekend's drive with a group of heavily modified Subies.

Cheers.

 

[sixtentouge]

Added a CANchecked MFD yesterday. Not that I have anything I think I really need to watch, and I prefer to log with my GScan3, but it's pretty cool for the price. Can't wait to get into it with the laptop and set up the pages how I want them

Also ordered all the stainless bits and a couple of bullet cans for the exhaust. Not real happy with what's available on the market here. They only sell legal here, and it just doesn't do what this car deserves. The high-end loud stuff out of Europe is over the "I'll just do it myself" price threshold. Leaving both cats in place. Two-bolt flange-back. Emissions in-tact, just looking for a little rumble.

 

[sixtentouge]

We'll see if there's a noticeable difference. Stock system is pretty solid, and they don't get hot enough on touge to really need replacing.

 

[sixtentouge]

Not much louder than stock, so my neighbors will be happy. I was on the fence between this and full WRC Noticeable power improvement above 5,500 rpm. Pulls all the way to 7,000 now. Will be interesting to log the boost and see what's happened. Might paint the tips matte-black.

 

[Sekred]

More boost or less?. Its a funny ECU.

 

[sixtentouge]

More boost or less?. Its a funny ECU.

Yea, the boost is closed-loop controlled with a target. Logging the target, the ECU pulls it back pretty hard past 5,500rpm. Doesn't make sense, as the engine is past peak cylinder pressure at that point, and it's safe. I've heard from a few of the people who tune ECUs for GRY rally and gymkhana cars that the HKS exhaust will have less boost fall off, regardless of the closed-loop target. This image shows a second or third gear pull, where you can see the ECM drops the target to as low as 201kPa at 7,000 rpm.

Whatever. It feels stronger in the top end, and that's a good thing. Not a waste of money for a little sound.

 

[Sekred]

The boost response is very similar to my Fiesta ST I use to own. The peak boost was around 1.4 bar at 5000 rpm and it would drop to around 1 bar at 6500 rpm which was the redline.
Two reasons I can think of why the ECU does this is to control engine torque and stop the turbo charger over speeding, meaning running out of efficiency.
I think the Ford EcoBoost engines were some of the first to use a Torque Based ECU.

 

[sixtentouge]

Japan RS*R Ti 2000 springs installed. F=4.08kg/mm R=4.29kg/mm. 2cm drop front and rear.

Stock had 1mm toe-in front and 3mm toe in rear. Drop didn't affect the rear, but the front moved to 3mm toe-out. Reset the bushings to neutral, and changed the front toe back to 1mm toe-in. Starting from where it was, and will add or take away toe from here. Camber started at 2° on all four corners stock, and has changed to 2.2°.

I really struggled with this decision. A custom-valved set of Ohlins DFVs was only going to cost US$3,100 through a friend, but really made no sense. The car will never see a track or competition. It's 100% winding road, where you never get close to the limit of the car. After a lot of handwringing,
a chat with a Toyota GR Garage that preps rally cars said to go with these springs on the stock RZHP dampers. The only goal here is to just have it "feel" better. A little less grip would be fantastic, actually.

Will report back after it stops raining

 

[sixtentouge]

Words cannot express how much I hate the "cams" Toyota uses for adjusting toe at the rear... After a drive, the toe had changed from 3mm in to 5mm in. After much struggle, the rear is now set at 0mm and the front at 2mm toe out.

 

[sixtentouge]

New skins. 235/40-18 CR-S V2. Just waiting for the wheels and pressure sensors. Should be here this week. Tried the stock wheels with 15mm Digicam spacers to see how the +30 offset felt. Was pretty happy with it, so went with 8.5J +35 Wedssport SA99R in PSB.

 

[sixtentouge]

Have the new wheels. Wedssport SA99R in PSB. 8.5j +35 and 60mm hub rings. SCM435 wheel nuts.

Unfortunately, the wait for pressure/temperature sensors continues... ETA 4 March.

Then... I find that with the aluminum-hat front rotors, you get about 6.5 turns of the wheel nut to hand tight... I posted about this in the "wheel and tire" forum, but ended up just doing the calculations myself... The tensile stress area calculation for the threads is a bit of a PITA, but With the stock Toyota 30MnB3 10.9 class, 12mmx1.5mm wheel studs, you end up needing just over 9mm of grip length for the tensile strength of the thread engagement area to equal that of the stud. The goal with fasteners is to always have the bolt or stud part before the threads strip. At 6.5 turns, we get 9.75mm of grip, but discount a little for the first half turn, or so, having less engagement.

That said... I don't like minimums, so have ordered 10mm longer studs, as well as four new axle nuts from Toyota.

And the wait continues.



I bought this car over building a KP61 Starlet (of which I've had many) because I wanted something I could just drive, and not have to work on. Many of my friends have "project cars that never leave the garage because they're always being fixed or fixed up... I said, "I'm not modifying this car...just going to drive it."

And here we are. Car torn apart...waiting

 

[sixtentouge]

10mm longer Kyo-Ei studs arrived this morning. I was going to change them the easy way, and popped the first one out with a pneumatic riveter. 10mm longer studs won't go in without bending the back plate, so.....I took it all apart and did it the right way. Have the right tools, so why not?

Popped the stock ones out with the 6X rivet gun, holding the hub flange in my hand, so as not to hammer the bearings. The bearing seal also contains the magnets for the wheel speed sensor, so better to be gentle. Hardly any spline to the factory studs, so they popped out really easy. Pressed the new ones in easy enough. Front hub bolts torque to about 175nm, and the caliper brackets to 107nm.

I see many people just drive a punch under locking dent in the axle nut before impacting it off. If you really want to make sure you don't screw up the axle threads when removing the nut, take a chisel and start to split it. Then run the sharp punch under it and it will peel the flange up and away, ensuring no contact with the threads. This means a new nut, but it's supposed to be one-time use only, anyway.

Waiting on sensors and new hub nuts. The rear has 8 turns, or 12mm of engagement (1x stud diameter), so I haven't convinced myself to change those yet...

 

[sixtentouge]

Finally!

Also, those hub bolts are supposed to be 130nm, not 175nm... But Toyota says 12mm 11T bolts are torqued to 175nm, and the hub bolts are 14, so no issues.

 

[sixtentouge]

Something we found with the stock-engine-class rally car is that it keeps pulling the inlet tube out of the airbox... The engine pitches way too much on hard transient back and forth between on and off throttle. So... Cusco Pitching Stopper. This is a motorsport part, not for use by people who don't like NVH

Feels pretty good over 2,000 rpm, but at idle, it can be pretty buzzy. Not scientific at all, but I compared both in the throttle-on direction. At exactly 1 ton of force, the Cusco mount moves 1mm. The stock mount got to 3mm, and was still at 700kg, which is where I stopped. Also, the stock mount's shape will allow much more movement in the engine-brake axis, where the Cusco is the same in both directions. Whatever...fun stuff.

This is my car, not the rally car, which belongs to Okinawa Toyota.

 

[sixtentouge]

I often refer to "the rally car," when talking about discovering this or that issue. The car belongs to Okinawa Toyota, and competes in the TGR Rally Series, an 11 stop series around Japan. Here are a few pics of it in my driveway.

 

[Michael Knight]

Very nice read, keep us posted!!

 

[sixtentouge]

Installing GR Garage Parts. Alcantara controls set tomorrow. Not a daily driver, and OEM quality parts, so might not need to be cleaned every week...

Steering wheel 45111-52010
Shift Knob 36303-52010-C0
Parking Brake 46201-52200

 

[sixtentouge]

I've probably removed airbags without disconnecting the battery a hundred times, but it still feels like disarming a Realistically, it's static electricity that will set it off, and I always touch the metal bits before unplugging
Anyway, Ultra Suede / Alcantara bits installed today. Interesting that the stock shift knob is weighted and pretty heavy, while the GRMN one is ultralight.

 

[Michael Knight]

I've probably removed airbags without disconnecting the battery a hundred times, but it still feels like disarming a Realistically, it's static electricity that will set it off, and I always touch the metal bits before unplugging
Anyway, Ultra Suede / Alcantara bits installed today. Interesting that the stock shift knob is weighted and pretty heavy, while the GRMN one is ultralight.

but weight in right places is not always a bad thing...

 

[Sekred]

I've probably removed airbags without disconnecting the battery a hundred times, but it still feels like disarming a Realistically, it's static electricity that will set it off, and I always touch the metal bits before unplugging
Anyway, Ultra Suede / Alcantara bits installed today. Interesting that the stock shift knob is weighted and pretty heavy, while the GRMN one is ultralight.

Do you think the shift is better with the GRMN knob?.