17 March 2018

Weather cleared up so an 80-mile drive broke in the new gears/synchros/LSD. Observations:

The ratios are noticeable closer, which isn’t a surprise but I kept catching myself pausing between gears, waiting to match gear speeds, a habit learned with the straight-cut gears, but when I let the clutch out with the new gear set, it’s clear I’m waiting too long. That’ll solve itself with time.

During the drive, 80 mph (GPS) was 4000 rpm, so back-calculating, the rolling diameter of the tires at speed is 25.1 inches (they compress about 0.5″ due to running ~15psi). That rpm is a bit high for cruising and will ironically serve to keep me more in line, read: driving slower on the freeway. Another reason to slow a bit is because boost is right there and ready to go by 4000 rpm, so it’s like riding a thoroughbred racehorse at a trot but who is ready to go right now. A third reason is that when in boost, fuel mileage takes a nosedive. That said, though the rpm is where MAP can reach maximum, since the throttle’s mostly closed, it’s only about 60 KPa (40 KPa below ambient). I read somewhere that a turbocharged engine can actually improve gas mileage somewhat by overcoming the pumping inefficiencies inherent in gasoline engines due to the throttle plate obstruction. Obviously not a big goal.

(Because of the rolling diameter of the rear tires, if I absolutely must reach 60mph in first gear, I either have to increase the rev limit to 8150 or put enough air in the rear tires to increase the OD to 25.6″, hah.)

After the drive, the OEM transmission fluid used for break-in was drained and replaced by magic oil supplied by the gear manufacture in unmarked bottles. Went for a short drive for gas and it “seems” to shift a bit easier, though it could also be my imagination. I assume it’s going to take several hundred miles for the carbon synchros to wear-in. Speaking of oil, I had an issue with the old transmission where the gear manufacturer, PPG, recommended brand X, while WaveTrac specifically recommended not using brand X. With the new transmission it’s similar, with Gear-X recommending their stuff (of course) and Giken recommending their stuff (of course) which, of course, wasn’t the same. I ended up getting both of them to hash it out on a group email and Giken finally said that Gear-X’s mystery oil would be fine.

There hasn’t been a peep out of the limited slip, or maybe I can’t hear it. Some people complain that Gikens makes noise, though others say it’s silent. Doesn’t matter either way, just a note.

If there was any question before, the test drive confirmed for sure that the engine mount has to be redone – way too much vibration.


16 March 2018

I started typing up what’s “on the list” in the Midlana forum and it just kept growing, so I thought I’d post it here as well since it sees more visitors. In no particular order.

The transmission shop is repairing and inspecting the transmission in preparation for its sale – ad here http://www.midlana.com/forum/viewtopic.php?f=22&p=8941#p8941

During the test drive, logger data was used to recalibrate the ECU’s calculated “gear”. The transmission doesn’t produce gear position directly but the ECU has the variables to create one. It’s handy for various things, such as boost-by-gear. Speaking of that, boost in 5th and 6th was increased (back) to the maximum value – that’ll be fun. Assuming it’s clear this weekend I’ll do a longer drive to fully break in the gears, then change the transmission oil as requested by the gear manufacturer.

I reworked the rear engine mount (which resists torque) while the engine was out but don’t like the result, too much vibration. I have a plan to basically roll my own and I’ll post pictures. The sweet thing is that the new design will make it easy to change the stiffness on the fly.

There’s the wings to make, which is a significant project but since it’s fairly compartmentalized, the car can continue to be driven while that’s underway.

There’s the rear diffuser, and right after that, filling in the gap above it, created when the damaged panel was cut out after my off at Willow Springs. Will probably use screen mesh for that.

Engine cover: Been wanting to redo it for awhile because without it, the car looks unfinished. More concerning though is the small worry about an engine fire at-speed, there’s a strong likelihood that the flames will be swept forward by the swirling air. That would be bad.

Upgrading the alternator. If I’m driving at night in stop-and-go traffic, the lights, electric water pump, radiator fan, fuel pump, and of course the ECU are all on, which is around 80 amps. I’m considering adding a small oil pump and cooler to the transmission (already have both) which moves the total current closer to potentially 90 amps at idle. The OEM Chevy pickup alternator produces around 14V when I first start the car, which is fine, but as it warms up it drops off. On the freeway with just the essentials (water pump and fuel pump), battery voltage ends up around 13.5V, and around 13V at idle when fully warm, lower than I’d like. I’d like to be able to run everything instead of having to sometimes load-shed things as the battery voltage drops off.

There are a couple solutions, like feeding cooling air to the alternator and putting on a slightly smaller-diameter pulley, though it’s being spun about as fast as it should be (18,000 alternator rpm at 8000 engine rpm). I’m currently leaning instead toward a unit that can support everything even at idle, such as the PowerMaster 478618. Better yet, it has remote sense and adjustable  output voltage .

Long ago I bought LED signal flashers because the old-school mechanical ones don’t work with LEDs. Until recently, LED car lights weren’t a “thing”, so it’s random chance how the mechanical flasher sockets are wired (since polarity didn’t matter). Of course mine are backwards backwards (both the turn and emergency flasher) so  the new LED-compatible flashers don’t work. I’ll have to pull out the fuse block and swap the pins.

Other things on the back burner are adding a transparent bulkhead window behind the seat to see what that does for possibly reducing wind and noise. Then there’s door fabrication. Pretty sure how I want to do them; it just endless details like: material, frame substructure, hinge type, fabrication, and placement, weather stripping, and a latch.

Lastly, I finally had enough of the buggy GoPro and have ordered a Sony action cam.

11 Mar 2018

The pieces of debris are from a synchronizer hub, which is probably the best of all the things it could have been. “Best” meaning that they’re not bits off the expensive aftermarket gears and being an OEM part, it’ll be less expensive to replace. The transmission will be sent to the same place that built the new one, which works out well since they regularly build PPG gearboxes. When the unit is put up for sale, it’ll be advertised as having been verified as 100%-good.

The rain let up so the car was taken out for a short test drive. The new gear ratios are closer, with first gear being the most noticeable. Now, the car sounds much more like a road-racing car when leaving a stop; with the lower ratio, the ratio has to be slipped a bit more. Being new, the synchros are a little sticky but that’s to be expected. It’s true what Honda owners said about these gears (and the ratios) are terrible – for OEM-weight cars.

With everything that was removed and replaced, it was good to see that nothing leaked or fell off. The rebuilt rear engine mount though, is transferring too much vibration. I’ll probably have to redo it again and am considering something like having a block mounted off the engine that in cruise conditions, “hovers” between two rubber-lined stops in the engine mount. That way, vibrations will only be transferred when under hard acceleration. We’ll see.