Project BRZ, Shifter Springs & Gearbox Fluid

The final lot of work in the week since I bought the car, was to sort out some shifting issues

Since I got the car, I had some drivability issues. I’ve previously mentioned the throttle and clutch response being an issue, but the gearbox also shifted pretty badly.

There is history of the gearbox having been rebuilt not long after the car was imported a few years ago, under warranty, due to a “whine in 3rd gear”. I confirmed with the workshop that did it that yes, it’s been rebuilt, but no they didn’t retain any info on exactly what was done.

It’s fine when driving, no whine now, but the shifting is pretty crap for a box that people rate quite highly. When cold it’s very hard to shift, and when warm pretty much every gear is notchy to shift into, and often crunches. There is also a fair bit of play in the shifter when in gear.

After extensive reading, I concluded that the gearbox fluid needed to be changed, and I wanted to try the uprated shifter springs to see if they made an improvement. Other than money, I had nothing to lose trying this.

I ordered some uprated shifter springs and three bottles of the recommended Motul Gear 300 75W90 gearbox oil

The car went up on the Quickjacks, for my first look under it. Over all, it’s very clean under there with minimal concerns. All the suspension bushes appear to be in serviceable condition.

I started with the shifter springs. To access the gearbox I removed the rear under tray (the black tray, not the silver one), which is secured with a whole lot of 10mm bolts

There are two springs, one either side of the gearbox

This one uses a 10mm hex. There is VERY little room to get this one out, so you will have to use a hex key, not a socket. I had to dig deep through my roll cab to find this as I normally use sockets or my big hex keys which had no chance of fitting.

The other is easier to access

Both were very tight. I guess when they were refitted after the rebuild, on the bench, they were done to FT (F’n Tight) instead of NM. They had also been refitted with good old grey RTV, which was a pain to clean off.

That second one uses a 27mm socket, and is a lot easier to access if you have a flex head ratchet. I had to use a cheater pipe to crack this one

Yay, sealant

Remove the springs (the one behind the 10mm plug may need a pick or magnet to slide it out) and replace them. Refit the plugs. There is a lot of talk online about cross threading the big one in the photo above, but just take your time to refit it by hand. Put some pressure on it, rotate it backwards a couple of times, and then it should wind right on in by hand with minimal effort.

I couldn’t get the torque wrench onto the 10mm one, so did that up gutentight by hand, and used the torque wrench on the 27mm one.

With the springs replaced, I located the drain and fill plugs on the side of the gearbox

Which are both 10mm hex. I cracked the upper one and then removed the lower drain plug to release a torrent of thick and quite dark fluid. The level was right, and no chunks came out, but the fluid wasn’t pretty. I cleaned the small amount of sludge off the drain plug magnet, replaced the crush washers on the plugs (18x24mm alu) and refit the drain plug.

I started to refill by using the nozzle on the bottle, but ended up sticking a pump in the bottle and pumping it in to the gearbox as it was quicker.

After about 2.2L went into the box, and it started to trickle out again, I refit the fill plug. A quick clean with brake clean, and we were done.

I refit the under tray, and lowered the car down.

Up top, I replaced the battery.

The sticker indicated that it had been replaced at 56,000km in 2017 (Heisei 29)

The cranking was quite slow, and I really didn’t want to get stuck somewhere.

I whipped the old one out

And stuck a nice new one in. Shame to lose the cool blue Subaru battery though

Cranking is much faster and more powerful now.

While under the bonnet, I also enlisted the help of my wife to bleed the clutch. It’s a weird system on this, where I couldn’t one-man bleed it. If you push the pedal down with the bleeder open, it didn’t push fluid out, you have to pump the pedal and hold it down with the bleeder closed and then open it to release the fluid. The pedal also gets stuck to the floor due to the helper spring. I definitely got some air through the hose, and the clutch does feel a bit less vague now.

So what’s the verdict? Well, It’s like a new, better, car. The throttle body clean I mentioned in my last post made a massive, completely unintentional, improvement. I can only presume the throttle plate was getting stuck closed and opened once a sufficient amount of angle/motor torque was dialled in by the pedal (usually around 15-20%), snapping it open. Now it opens straight off the pedal being pressed, and the response is significantly better. I no longer use the throttle controller to dull the pedal response, I may even start using sport mode.

Secondly, the gearbox fluid completely changed the feel of the box. No longer is it stiff and hard to get into gears, it’s a lot smoother, but all the notchy and crunchy shifts have completely gone. It went from a gearbox I legit thought was on its last legs, to one that’s pretty good to use. Not MX5 (or Alto) levels of accurate and smooth, but much better.

The shifter springs have also taken out a lot of the in-gear play in the shifter, which makes the selection of gears more accurate and it no longer sort of wobbles into gear, occasionally being blocked by the gate. There is still some play, but it’s no longer an issue.

The combination of these fixes means I no longer bunny hop and jerk away from a stop, and it’s made the whole driving experience much more enjoyable.

And finally, the last improvement until the next lot of parts arrive, new tires and an alignment.

I knew the rear tires were bad; the previous owner warned me one would need replacing for a WOF, and the other was new, but mismatched, from having a puncture. The fronts, appeared fine.

Knowing I was going to want to drive this car spiritedly, I ordered some Bridgestone RE003s, in the stock 215/45R17 size. I can now confirm you can fit a full set of four in the car.

Today, I dropped the car in for the tires to be swapped over and an alignment. I’ll tell you what, I’m glad I did. First, the front tires were also trashed. They’re cheap ditch finders, but it turns out the inside edge of both were chewed down to the secondary rubber, so they’re no good. One rear was also worn down on the inside edge.

One surprise to me with the old tires was how soft they are. After handling the RE003s which are quite a firm carcass, the cheapies have no structural integrity at all. The sidewalls squish under the weight of its own mass, and the belts in the tread just sink down if you apply any pressure.

The alignment explained it all though; the excessive wear, the weird tracking, and the shaking when driving. That’s a heck of a lot of front toe. The RH front was 4mm toe out, and the LH front was 2.2mm toe in, basically driving like this / / but with one side pointing right almost twice as much as the other.

I could do with some front camber though…

Driving down the road now, I could immediately feel the car was smoother. I didn’t realise it must have been shaking or something at lower speeds too, as it feels different even around 50kph. The steering is more responsive and no longer wanders down the road.

Of course, I had to break in the new tires, so a quick drive over a local hilly road was in order. Suddenly, after all this work, the car finally felt cohesive and like it was all working together, not trying to fight itself. It feels very good to drive now, and I’m finally bonding with it, instead of just liking it, seeing the potential in it, but being annoyed by how it feels.

I still need to clean it, but here are a couple of quick photos with the new rubber