16 Sept 2019

This weekend is the Virginia City Hill Climb and me and my brother are about set. My brother’s car had a bit of a hiccup, with a new noise coming from the differential. Turned out that some of the ring gear teeth were cracked, and he was told that’s because this model diff is good to ~350hp, and he’s running 450whp through it. That’s a bit surprising given that the straight axle assembly weighs 150 lbs. Anyway, it’s fixed now, though he’s a bit concerned though about how long it’ll last. I urged him to take it easy, not stressing the gears, and to baby it up the hill, hah.

At the same time, he also had his old torque-sensing gear differential swapped back in, replacing the clutch type. I asked why, given that the general consensus is that clutch differentials consistently yield faster lap times. He said that at a track day event, he lifted a tire under braking—once—and smoked the differential clutches on that side and ruining it, so he’s done with that type.

Speaking of differentials, it reminds me of the many changes that have been made to Midlana since her last track outing: higher compression, better cam, larger turbo, overhead intercooler and ducting, retuned, different transmission gear ratios, different type differential, stickier tires, diffuser, different shock settings and spring rates! A good reason to do a lot of practice runs and take it easy learning what’s effectively a different car.

The weather this weekend looks promising, with temperatures expected to be in the low to mid-70s. Cool enough that we won’t overheat, and warm enough that the tires will probably get up to temperature.

The cars will be towed up Wednesday (a 9-hr tow, ugh), then driven up to Lake Tahoe on Thursday for some sightseeing and picture taking. Friday is more local sightseeing, which is a kind of a big deal around Virginia City, because this is where the Comstock Lode was discovered, the largest silver mining area in the world, at one time at least. Mark Twain ran a newspaper in Virginia City for a few years (with Wikipedia saying that he was challenged to no less than four duals during that time). Friday evening is tech inspection; Saturday is practice, and all of Sunday’s runs are times, with your best being “the one.”

I’m taking both the Sony and GoPro action cams and hope (with a glare toward the GoPro) to get some good video to work with. Editing it down will take a while, but I’ll be posting pictures as they’re taken through my Instagram feed (Midlana1). Don’t expect any updates here until next Monday or Tuesday night.

In other news, the wife said that there’s a big branch from one of our pine trees hanging over (and on) the neighbor’s fence, and she wanted to spend ~$1000 paying someone to trim it. Since she sleeps in, I went out early “unmolested” and cut up the offending branch (and yes, the voice in the head did point out that I may be getting too old to be climbing trees—I paid no attention). Granted, I didn’t trim the entire tree, but I choose to look at it as having just “paid” for a good portion of my upcoming trip. That’s my story and I’m sticking to it.

4 Sept 2019

Finishing up in the appearance department, the intercooler was painted and now the car looks a lot more finished. While still motivated, the right side panel was also opened up; it remains to be seen what its effect on cooling is.

In other news, the replacement cross feed screw for the lathe arrived. Disassembly of the existing cross slide screw showed the expected signs of a hard life; the middle portion is much more worn than the ends. The current thinking is to machine down the replacement screw and press/pin it to the front portion of the existing assembly. That seems easier than trying to machine the entire thing, though I might change my mind later. The bronze split nuts are also heavily worn and can be rocked back and forth on even the new shaft. I’ve never purchased bronze before and was surprised that a 1.5 x 1.5 x 6″ piece is $60 (from McMaster).

The good news is that I have a buddy who has this same model lathe will be making the same repairs. He already has the oddball 7/8-8 LH tap, necessary for making new nuts, and I can probably sell him half the section of bronze. Anyway, that, the electronic lead screw, and wooden gear clock will get more attention after the hillclimb.

2 September 2019

Actual Midlana content!

With the hillclimb coming up, there’s a few chores to take care of, with finally fabricating a replacement engine cover being the first. Longtime readers will recall that repositioning the intercooler to the top of the engine compartment meant that the previous nice clean engine cover no longer fit; believe me, I tried. The new cover is two-piece to surround the intercooler core, and to be removable. As mentioned before, the engine cover buys time by keeping flames out of the passenger compartment in the event of an engine bay fire.

I forgot that months (years?) ago, I’d starting taping paper templates to the back of the old engine cover to figure out sizing and where to separate the two, so starting with them saved some time. Anyway, it took me back me back in time to making the various aluminum panels on Midlana, which included relearning various fabrication tips, like “make sure to apply pressure to the riveter away from the panel so that when the rivet stem snaps, the tool doesn’t leave a scratch.” Oops. The pictures pretty much step through the details.

I again want to mention how great yellow iridite (also known as “Bonderite” or “Alodine”) is on aluminum, as it’s an excellent way to prep for paint. The two part solution degreases, etches, and protects the metal (with no treatment, aluminum feels oily). Paint sticks way better with it, and best of all, it’s all done at room temperature and applied via either dipping or brushing the parts, then rinsed off with ordinary water.

The riveted-on green vent panel was removed from the old engine cover and reused. There is some concern that engine compartment cooling may be limited by now having both upper and lower covers. Also unclear is whether the right-hand side vent should be opened up. The left side was always open, originally for the side-mounted intercooler. The right vent was to feed air to an oil cooler, but was never implemented (the engine uses an oil-to-coolant heat exchanger instead). Anyway, easy enough to try it.

I chose to go with ordinary flat black paint instead of the metallic green, mostly because I’m lazy, and also because the dark green is so close to black that the two colors won’t jump out as an obvious mismatch. Still on the to-do list is painting the intercooler end tanks and side plates.

The weather this year is been surprisingly mild; we’ve only run the A/C a few times, so with it being September, there was some talk that SoCal might avoid the usual heat. Hah. The wise old farmer’s advice about, “the first week of September is always the hottest” has proven astonishingly accurate again. Right to the day, hot humid weather moved in and chased me out of the garage a bit early. Sweating is okay up to a point, but when I keep drinking liquids with no need to run to the house, that’s enough for the day.

In other news, parts for the electronic lead screw are showing up, but nothing much to show until more parts are here. Oh, and in other news, 7/8-8 left-hand Acme thread (a very odd thread!) was ordered to replace the worn cross feed screw in the lathe. Though the old lead screw hasn’t be removed yet, it’s clear that it’s worn because when backlash is set to “reasonable” in the middle of its travel, it binds up towards both ends. Backlash is a very subjective thing; some people are fine with a fair bit, and some are not. I’m somewhere in the middle.