The Glorious Renewal of Mikuvan and The Winter of Ven: Operation Give Me A Brake! Again

You might have seen Elf on a Shelf, but have you seen….

…dashboard master cylinder?!

I’m doing a lot of “van fill” here lately because… well, frankly, that’s what I’ve been up to for the most part, when I haven’t been working on Overhaul in the past few months. With these systemic repairs and some other work on the cooling system that also came along, Mikuvan is probably in the best mechanical condition it’ll be in for a long time. It’s great to be able to crank on things without being disturbed or getting rained/snowed on!

I’ve obviously been putting off figuring out how to structure now two entire build seasons of Overhaul progress. I can probably put together a legitimate e-book and sell it with how much there is to go through, with almost 700 build photos and over a hundred CAD screenshots. The problem in part is now I know what didn’t work, and so need to figure out if I should present the narrative as if I didn’t know yet, or cut to the chase and integrate it better.

This series of posts will be some more good ol’ Zen and the Art of Van Maintenance, covering brake system related things I had to do on Mikuvan from last fall into just a few months ago. It’s a time skip featuring work that was done in stages, but is better presented together as a narrative. So if you are into brake, axle, and master cylinder service on your 3rd-generation 1980s Delica, stick around!

The backstory to all this was explained in my post of everything. With as hard as I’ve been whomping on Mikuvan and driving it like a Miata, some of the systems are showing their age. The most pressing matter was a leaking brake master cylinder, which towards the end of summer began dribbling with every stop. As things got colder, it got worse, to the point where I should 1. uhh, probably stop driving it and 2. had to put shop rags around the steering column to catch the brake fluid.

So priority one was getting this thing replaced. I also replaced the front brake calipers and rotors again from their last round on this very site in 2013! But, that’s a more rote job so I’ll leave it for last. Details to come will also include diving into the slowly self-imploding power steering pump while it was apart and on jackstands with this master cylinder replacement.

Yeah, so about that master cylinder. I’m not sure when it began leaking, but it got pretty bad over the course of a few months. You can see how the brake fluid has eaten the paint off the booster cylinder on the upper left. While it never stopped stopping, I figured it was only a matter of time before it did!

Luckily, I ordered a new master all the way back in 2013 when I was scraping parts off Rock Auto for the first few times (is it still good, I wonder….), and it’s traveled with me to this day. Reading the shop book on how to replace it, though, was another “Damn, this thing is weird” moment.

Alright, the dashboard instrument panel area has to come off first. This is all fairly simple with unplugging cables and popping switches out of their housings. Hmm, the master cylinder is allegedly under here somewhere…

Ahh, there it is.

Connected to the reservoir (mounted remotely by the driver’s door) with some rubber caps, it sits with the brake booster facing you. The brake pedal linkage does a 180 degree turn and the pushrod pokes towards you!

I suppose that’s not TOO strange, as some earlier American full-size vans had a 90 degree linkage doing the same job.

Well, this thing’s lived in a plastic bag for 30 years probably. Let’s hope it’s still functional…

After moving the dashboard harness aside, I used the remote hose clip grabberator tool to move the brake hoses off the rubber caps. Before doing this, I used a leftover epoxy syringe to draw fluid out of the reservoir as much as I could, so it wouldn’t spill everywhere. Not that it didn’t do so anyway….

At this point I realized I didn’t actually own flare nut wrenches, so out comes the DIY flare nut wrench made from your least favorite 10mm box wrench. This is a counter-indicated activity, as flare nut wrenches are made to tighter fits and to grip more of the sides of the (usually soft metal like brass or plain steel) fitting. It worked out fine for me, however.

Also notice the little vacuum line caps I shoved over the fittings so I don’t spill out more of the fluid.

Once the wire harnesses and hoses are removed, the access itself isn’t bad. I used a 1/4″ drive ratchet with an unusually long handle for its size (for better leverage) and a small extension with a wobble drive end. The wobble is helpful due to the vacuum? line that runs across the assembly (it can be seen to the immediate right of the ratchet handle, in the center between the two master cylinder cap fittings), but I suppose you can also beast it.

Old master cylinder now removed. The area is pretty grungy, and there’s more eaten-away paint where it’s been leaking from the front seal. I cleaned up this area pretty thoroughly with teratogenic solvents and a small wire brush, wiping it all up with shop towels.

iNsTaLlAtIon Is ThE OpPoSiTe oF ReMOvaL – those dreadful words in every single shop manual. I mean, there’s not much trickery here, that’s really how it is. Before mounting the master cylinder, the fittings need to be oriented roughly how they’re shown here – front circuit pointed dead left, and rear circuit at the 45 degrees.

I’ve hooked the hoses and clips back up now and recovered all the dashboard wiring, previously shoved sideways. I took this opportunity while I was staring the speedometer cable in the eyes to force-feed it a bunch of 3-in-1 oil. This runs downwards and all the way to the transmission, and I figure any lubrication it had is long dry.

(Followup note: The cable is now so well lubed it has no damping left, and the speedometer needle has what I call “AC RMS” noise, furiously wiggling even at highway speeds around the actual average speed!)

In all, it either wasn’t as bad as the shop book made it out to be, or I’m jaded and consider this relatively simple van maintenance. The rest of this story is now about a brake job:

The draggy brake caliper on the front right got drastically worse after a weekend mountain run, and was bad enough that I was smelling brake pad (and took a noticeable mileage hit). So, Mikuvan got to sit on the bench for a few weeks before I got to the caliper replacement and the master cylinder work shortly thereafter.

I decided to just order more new (well, remanufactured) calipers instead of rebuild kits for the existing ones. With something as uncommon as the USDM Mitsubishi Delica, I’d rather have more parts than not enough. I ordered the rebuild kits anyway, but will be hiding them with the old calipers in case I or someone else needs them some day. And this is how it begins – the seed of my “Warehouse of assorted car parts someone will neeed” that my estate will surely one day have to auction off.

One quirk of “obsolete van” service? The parts you get for the left and right hand sides are probably not going to be the same. At all. These two brake calipers nominally had the same part number and were both branded the same rebuilds, but they are definitely different from each other. One had an original Mitsubishi star on it, the other was…. something else.

These brake rotors, too. Maybe the same thickness, OD/ID, and bolt pattern is all that matters, but it’s just funny to have one that has twice the number of cooling vanes as the other.

Disengaging these old truck brakes is very simple. No special tools needed save for a simple C clamp!

This took…. a lot of effort. Why?

Looks like the culprit is this torn rubber shield for the brake cylinder. This would allow weather in, and probably caused this piston to seize in the bore once corrosion started ruining fits and finishes.

Check out the well-cooked patch of brake pad that’s been burnt onto the rotor, as well as the heat-crazing that’s starting to form on the surface.

A lot of effort was needed to break the nut and bolt apart. They’ve had over six years of Natural Loctite buildup from Boston winters, after all. I didn’t consider the hardware useable at all after busting them apart, and so I ordered new JIS-standard hex cap screws and nuts.

Why specifically JIS? Well, JIS fasteners have smaller head and drive sizes than the more typical “metric” found in the US which is more likely to be DIN or ISO. The head of the screw had to fit fully inside the counterbores on the wheel hubs, and the nuts had to not interfere with the hub as well.

While I was waiting for the SPECIAL BOLTS OVERNIGHTED FROM JAPAN!!! (McMaster) to show up, I did…. what everyone expected me to do.

Consider it an act of rust prevention, or vanity. No, it’s not high temperature paint. No, I don’t care all that much, why?

The next day, JIS bolts! Besides having different drive sizes for hex and sockets, JIS also has a different fine and coarse thread definition. In M10, the typical pitch for coarse thread is 1.5mm and the fine thread is 1.25mm. Recall my adventure with repairing the exhaust manifold where I found out someone babooned a 1.25mm nut onto a JIS 1.0mm fine threaded stud.

See what I mean about those counterbores the heads had to fit into? Strictly speaking, a regular ol’ 17mm head would have fit here, but…. there would be no way to put a socket on it to install!

I discovered a folly immediately after test fitting the new bolt arrangement. I got screws which were the nearest 10mm to avoid having to get special automotive screw lengths. Well, they stick out just a little too far compared to the previous screws….

And that meant the ends of the screws hit this irritating high spot in the brake caliper castings.

I had to demolish my brand new Miku Magenta painted calipers with a grinding wheel to free up this fit!

So there we have it. Hot pink calipers installed on both sides.

The calipers did come with the slide pins greased, but I didn’t know how long they’ve been sitting in a box – the grease felt pretty dried out. I therefore unscrewed the slide pins and refreshed the grease with some copper filled grease.

After the master cylinder install, I took the opportunity to fully flush the brake lines, something I only did before in 2013 when I first went through the brake system. Plenty of “Brakerade” was generated once more. Delicious, delicious skin cancer.

Finally, while the dashboard was taken apart, I refreshed all the slowly dying Inexpensive Chinese Van Lights.

And we’re back together. At this point some time in January, stopping was fine, but turning was questionable. The power steering pump is next!