MGB - master cylinders (Part 1)

Another post about the ongoing work on the MGB. Today's post covers the removal of the brake and clutch master cylinders. This got long, like so many of my posts these days, so I split it into two, with the follow-up post covering the re-assembly and re-install. It should be noted that sometimes I revert back to a sworn-at previous owner (SAPO) and start removing things without taking pictures. This is one of those times, so the pictures are from either the re-assembly or the internet. Sorry. Sometimes I suck too.

Why?
This is as logical a place to start as any. "After the list of other things that have been done why the (expletive) would you open up yet another system?" Yeah.. that's a really great question. It's not because I'm sadistic. You see, I started with the brakes. Long before I discovered the rust-thru on the floors, or learned about the front suspension having window insulation acting as bushings, I tried to fix the brakes. I completely redid them at the wheels. I even replaced the hoses with nice new ones, but I couldn't get the rear's to bleed. Turned out, the master cylinder wasn't pushing fluid to the rear, so it had to go. After some reading, I learned that for some weird flaw of nature the clutch master cylinder fails within 6 months of replacing the brake master cylinder if you don't replace them at the same time. Rather than tempt Murphy's Law, I figured I'd just get after it. Besides, winter was coming so the little car was going into the garage anyway.....

Remove the Brake Master Cylinder (MC)

my engine bay - before

After I tried all sorts of combinations of efforts to remove things, I figured out that it wasn't nearly as complicated as I (and the internets) was making it. First, remove the electrical bits: the pressure sensor and the brake-light switch. The first unplugs, the second unthreads. Then, remove the brake hard-lines from the master cylinder. There are three, two head to each of the front wheels and one heads for the rear. Put a small catch-pan under the master cylinder before you start opening these or you'll get brake fluid dripping all over the driver side of your engine bay. It is a really small space under there, so I used a washed out yogurt container as a catch-pan. I taped plastic on the brake line ends to keep some water out (and brake fluid in), but after the front end suspension work, the lines are completely clear. If you're just pulling one and slapping a new one in, It might be worth doing. I didn't see the downside except consuming 10 minutes of my time. Once the fluid lines are detached, remove the two nut/bolts which hold it to the brake booster. With a wiggle, it should come right out.

Remove Brake Booster?

not mine, but better angle

With the brake MC out of the way, the next in line is the brake booster. This unit takes vacuum from the engine and uses it to help you stop. Very clever. First thing to remove is the hose from the engine to the brake booster. If your rubber is as old as mine, make a note of replacing it. The booster is held onto what's called the pedal box from within the box, so before we can go any further, we need to pull the lid off the box. It is held on with a bunch of little fasteners. Depending on how much your car was messed with, these could be bolts or screws, Phillips head, slotted or hex. Or a combination. Mad love for prior owners. Someone will be cursing me this way one day. Anyway, remove the fasteners and the lid on top. Inside is the magic where the pedal action is translated into brake or clutch motion. In here, you can see how the brake pedal actuates a lever that runs forward into the brake booster and how the clutch pedal hinges on a pin connected to the clutch MC between the pedal box and the firewall. Whoa. So.. maybe this is why everyone says to replace the clutch MC at the same time as the brake. You have to get so deep anyway, you just might as well.

So, how do you get this thing out? You can try starting by removing the pin connecting the brake pedal to the lever. This is a royal PITA. You need inhuman fingers to do this. Same goes for the clutch pedal/MC and even getting the brake booster off. After the fact, I figured out that you don't need to separate the brake booster from the pedal box at this point. You can just remove the booster with box all at once. Whaaa???

Remove the Clutch Hydraulics and Pedal Box

thank you eBay for your blurry picture

Skipping over the brake booster, we move to the clutch master cylinder (MC). Disconnect the hydraulic line that runs along the firewall. Again, I wrapped it in plastic wrap and then taped it sealed. Now, the only thing that is holding the clutch master cylinder, the brake booster, and the pedals in the car are the little bolts which are holding the pedal box in. Many of them are addressed from the driver footwell. Only a couple (those on the engine-side of the box) are removed from above. They are different sizes, which is a little weird. Anyway, once the box is free, the entire unit can be coaxed out of the car.... but wait: the pedals are too wide to fit through the hole! Lift the box and pedals as a unit and once you have it up as high as it will go straight up, twist it counter-clockwise while you lift and you can get another inch or so. That little bit is enough for you to get access to the clutch pivot bolt. The bolthead is sticking out the left side of the box. 1/2" socket will remove it, and the pedal will be free enough for you to get the unit out. Seriously, it works. The pedal will dangle a little strangely, but the 2 pedals will fit out of the hole this way, even with brand new pads.

Separate
With the box on your bench, you can easily pull the various parts off. The brake booster is held on with 4 1/2" nuts, and the pin from the brake pedal is easier to get to when you're not leaning over a wing (fender). The clutch MC is held on with 2 1/2" bolts. One of them twists into a fixed nut, the other needs a wrench on the nut on the inside. Like the brake pin, the clutch pin is easier to get off at this point. I found needle-nose pliers to be up to the task.

Now, your pedal box, master cylinders, brake booster and pedals are all apart. In part 2, I'll cover cleaning, painting and re-assembly. Thanks, as always, for following along.

MGB - floor pans (Part 3)

Continuing the effort of replacing the floor pans. In Part 1, I talked through decisions about parts and methods. In Part 2, we removed the old pans. Today, we focus on prepping the new pans and getting them welded in.

Context

paint from below, p-side

Remember that the original pans were spot-welded to the rails. This was done at the factory where very long spot-welder arms are available and things like the doors, dashboard, etc aren't yet installed, so there are fewer obstacles. Even with some crazy-long spot welder extension arms, you will not be able to avoid another solution for some of the mounting locations. Your options: seam weld from below or plug weld from above. At least on the right side, the wires, tubes and cable make a seam-weld from below option very difficult. Most do-at-home folks go the plug-weld route. The folks at British Auto Works in North Plains run seam welds around the outer edge from above, but plug weld the inner frame rails. If you're going to do this, they recommend running beads that are about an inch long and space them every couple of inches to prevent warping. It will hold at least as well, if not better, than plug welding the whole thing.

Fitment

p-side pan prep

The passenger floor fit like it was supposed to fit. It literally dropped right into place. It wouldn't shift too much side to side or front to back, but my hammer/chisel work bent some of the edge along the transmission tunnel, so I had to work the metal back into shape. Once the floor was stable (no wobble or weird clunks from my stepping on it), it was ready to go. The driver (left) side, however, did not fit right. The front right corner on the pan assumed the floor had a squared-off point to it, but my floor had a rounded edge. I had to bend the corner of the pan to test fit and then cut it off with my grinder for welding it in. It would not naturally sit flat either, so I had to be extra careful as I did my first few welds to get the floor to hold flat. You may experience a similar situation, even with the OEM pans. We know the aftermarket ones don't fit without cutting, so be advised.

What's a "Plug Weld"?
A plug weld is performed by drilling a hole through one material, setting that on top of a second piece of material and welding the two pieces together through the hole. In our case, we are making 1/4" holes in the new flooring. The weld is formed by setting the MIG wire into the center of the plug hole, pulling the trigger to start forming a puddle and then extending the puddle into the floor after the puddle has started to grab into the frame rail. Before we can weld, we need to poke holes in the floor, but where? I tried 2 methods. I'll explain them next.

Option 1 - Paint and Measure
Once the frame rails are clean, you just can't help yourself. You just have to drop the new floor on there and admire how nice it looks. It looks so pretty. Looking at the passenger-side pan sitting there, I wanted an easy way to spot the holes. I fiddled with the pan to make sure it was exactly where I wanted it and then set some tool boxes on top so it held still and firm on the rails. Then, I grabbed a can of white spray paint, slid underneath and spray-painted the edges of the frame rails where they met the underside of the new pan. When I lifted the pan off the rails, there were clear white lines showing where the frame rails were. I ran blue tape along those edges and marked drill holes every inch or so with a sharpie. The p-side prep picture on the right shows what the prepared pan looked like.

Option 2 - Use Old Flooring

using old floor, d-side

When I removed the driver (left) side floor pan edges, I didn't crumple them up as I went. Instead, I would separate a section and then cut it free with tin-snips when the trim started getting in the way. Once all of them were free, I arranged them on the ground with the larger sections I had cut out earlier. With the puzzle so completed, I could see where the old spot welds were. So, I arranged the puzzle onto the bottom of the new pan, and shot spray-paint through the taped-on floor-pan edges. When I removed the old edges, I had dots showing me where to drill the plug-weld holes.

Drill Baby Drill
Regardless of which method you choose, drilling the plug holes is a two-step process. First you drill a pilot hole and then you drill out to 1/4". I suppose a step-bit would work so that would be only one drill effort. Similar to cutting out the spot welds, this is time consuming. I understand why British Auto Works (and probably most other shops) reduce costs by seam welding the outer edges. For that reason, I drilled plug welds into the floor to correspond to the inner frame rails, and only a few around the outer edge of the p-side pan. My paint-from-below method worked pretty well, though my alignment slipped a little bit and I had a few holes that didn't align with the rail.

On the driver (left) side, I chose to plug weld the whole thing, so that meant more drilling on that pan. The holes I produced with Option 2 were an exact match. They aligned on the rails perfectly. Unfortunately, the holes that cut all the way through the frame rail were now completely exposed as well. The drilling out of a single pan took me 2-3 hours and overall there really wasn't that much of a difference in time between the two sides, even though there were far fewer holes on the p-side. That doesn't math-out logically, but that's what happened. The all-in time at this point is over 14 hours and no pans are welded in yet.

Plug Welding

If the grinding was the best part of Part 2, then the welding was the best part of Part 3. I borrowed a 110V Lincoln MIG welder from my wife's sister's boyfriend, and bought a small 20# tank of "steel mix" gas for the project (cost me $100 for the tank plus gas-fill on craigslist). I've heard these small tanks have 6-8 hours of gas in them, so that should be enough for multiple pan replacement projects. Once I had the passenger side ready to weld, I hosted my wife's sister and her boyfriend for a welding party. The plan was simple: he shows us how to weld, and I keep a fresh beer in his hand. It worked out well for everyone. While he got the welder set up, he taught us with welding scraps from the old torn-out floor. This gave us opportunity to work on pieces that didn't matter, but were the right thickness and material. We ran the temp / voltage as high as it would go (D) and the feed set pretty fast too (just below 9). Because if the thickness of the rails, the high-voltage setting makes sense. For other work, like repairing the rear bulkhead the previous owner cut a big hole in, I'll need to bring the temp way down. Before we were done for the evening, the passenger pan was in, and 3 of us learned how to MIG weld, including my wife's sister. Very fun.

During the actual weld-in, we had setbacks, of course, like some burn-through of the pan when we novices tried to run a bead, or small fires from grease or paint catching fire from the welding. Not to worry, though, they were small enough to blow out. Still, the decision to weld on the driveway rather than the standard low-ceiling garage turned out to be a good idea. We tested a few of the welds just for curiosity sake by banging on them with a hammer and trying to separate the panel with pressure from below. No dice.

I've gone back and forth about grinding down the plug-weld humps. I know the floor is going to be covered with sound reducer, a carpet pad and then carpeting, so no one would ever really see them. At this point, though, I'm trying to get the car on the road before the weather turns, so maybe I'll grind the humps down under a canopy once the weather changes this fall. Or I may just leave them alone, and focus energy on value-adding efforts, which grinding down weld-humps in an area no one will ever see... frankly isn't.

That's it for today. My final steps are seam-sealing the floor edges, and getting some paint or undercoating on the steel pans. That work may not be interesting enough to warrant a post. After that's done, I am going to focus on getting the fuel system and master cylinders re-installed. Expect posts on those efforts soon. As always, thanks for following along.

MGB - floor pans (Part 2)

Today we continue the saga of replacing the floor pans in the MGB. In Part 1 (See MGB - floor pans Part 1), we identified the issue, and made decisions on parts and a method. Today, we get into removing the old pans.

Get Safe

$15 at Harbor Freight

This could be a euphemism for something else, but in this case, it is exactly what it says: safety first. You are going to be cutting and then welding steel. This throws lots of sparks. Your car runs on gasoline which is designed to explode when a vapor meets a spark. When you put these together, my best advice is to remove the fuel system entirely and then wait a couple of days to let the fumes leave the remaining lines. That's what I did, and I'll post on that later. Consider too, that the cutoff wheel throws dirt and dust everywhere so wear eye protection at least. I use a face shield, long sleeves, and denim pants to protest myself. And yes that gets hot in the summer when you're working in the sun on your driveway.

Clear Your Paths
Under the right (passenger in the US) side floor, there are small pipes and cables that you don't want to set your cutoff wheel into. These pipes and cables are held to the floor underside with nuts and brackets, and further held into place with some rubber bits. Remove the nuts and the brackets and pull the rubber bits out. Toss all of it into a ziplock and mark it as part of the right floor. You'll want them later. Let the cables and pipes hang as far out of the way as possible. Among these is the fuel feed line, the vapor line and the main power supply from the battery. All super important.

blue tape the cut lines

I had the brake and clutch pedals already removed from my efforts on the master cylinders (post on that coming). I chose to remove the accelerator pedal as well to improve my access. Since it is held on with a bolt and the cable is held on with a pin, this removal is very easy. Now that my floor has been removed, I couldn't imagine how much harder this would have been with them still in place. Mental picture: you're lying down on the door frame, hips-to-feet sprawled out through the driver-door, with your arms extended into the foot-well with a grinder spinning a cut-off wheel at 11,000 RPM. Getting the cuts right without accidentally catching the underside of the brake pedal sounds virtually impossible. I highly recommend removing the pedals, if you can.

Mark the Spot
Before you grab your grinder, you need to find the frame sections underneath. On the right (passenger) side, I followed instructions I found online, where I drilled holes at the corners of various support structures. I then connected those dots with blue painters tape and then drew on those lines with a sharpie so I had clear lines to follow. This did work, but for the left (driver in the US) side, I thought I could do it with fewer steps. The first step is the same: with one had under the car and the other resting on the top of the floor, tap with your bottom hand at the corners of the beams. Feel for the tapping with your top hand, and keep circling in on the spot by tapping until you know exactly where the spot is. Mark it with a sharpie. On the right side, I drilled a hole. On the left, I just marked it and moved on. I ultimately found that the drilling was unnecessary. There are 2 main under-floor rails, one runs from the transmission hump to the edge under the front seat mounts. The other runs from that cross rail between the legs to the front. In the US model, imagine a rail running straight at the brake pedal. These rails are about 2 inches wide, but there is only about 1/2" lip that it spot-welded to.

not-so-fun part

Measure Twice, Cut Once
This phrase has been made famous by arm-chair trades-persons dating back to the stone cutters in Egypt. Still, its a good practice. Double check your marked lines to make sure that you didn't draw a line through a section of frame. Also consider if your cut-path will send you through any of the cables or pipes you moved aside earlier. Cutting through a fuel line, even if it's empty, really sucks. Yes, I did and I'll explain how I fixed it later. Along the rear edge, there are two heavier sections in the corners that are not to be cut out. They create structural stability and should only be removed it they are not doing that job. My bar had a pretty rusty floor, but those sections were fine. Make sure your cut lines take these sections into account.

The Fun Part
The floor is cut out in 3 or 4 sections, separated by the frame rails. Cut the rear out first. The rear section comes out as one large, nearly square piece, and the steel cuts pretty quickly once you get started. With the rear cut and pulled out of the way, you can see the cable, etc on the right side. Next, I cut the outer of the two forward sections. Again, this allowed me to avoid the cables, etc on the right (passenger) side. Last, I cut the inner section, and it was all pretty clean except I nicked the fuel line for about an inch, leaving a nice gash in the metal fuel line. At this point, I was glad I'd pulled the fuel tank, and let the system sit for a week or so.

The Bit

spot weld cutter

With the main sections of the floor out of the way, it feels like you're really on your way. That's until you start to understand what comes next. The floor was attached to the rails at the factory with a big spot-welder, placing a weld every inch or so along both rails and around the outer edge. Those spot welds are what is holding that last inch of steel to the car. I have read where some folks (who are far more skilled with a grinder than I) were able to cut these sections off without any other tool. High praise to them. I am no way skilled enough for that, so I went the more labor-intensive route.

Hit Harbor Freight and buy at least 2 spot-weld cutting bits. They are small, fit in your drill, like a regular drill bit, but they are designed to cut spot welds. The shiny, silver point in the center of the bit is set into the center of the weld, and then you run the drill at a slow speed to cut the sheet metal around the weld. This allows the rest of the sheet metal to rise from the rail. Each bit is reverse-able, so as you burn out the teeth, you can pop it into a vice, loosen it with a 1/4" spanner, flip the bit and tighten. One bit lasts twice as long... which still isn't that long if you run your drill too fast.

So, now that you understand the weld-cutter, slap a grinding wheel or wire wheel onto your grinder and grind on the remaining bits of floor so you can find the spot welds. Between rust, paint and black-tar seam-sealer, you may have to grind a bit to find the spot welds. If you can't find them all or you don't want to grind to find them, there is an alternative; you just need to be willing to use a framing hammer and chisel.

The Not-So-Fun Part

cleaned up

With your spot weld cutter in your drill, and a framing hammer / chisel nearby, pick a spot to start. I went with the easiest to get to: the rear section. The spot welds are easier to find back here too. Pick a spot weld, cut it out (slowly on the drill!). If the metal didn't make a "ting" noise while cutting, it may not be completely free. Given time you'll get the hang of it where you're not cutting too deep (through the frame) nor too shallow (and leaving the metal well attached). If the metal didn't separate, get under the metal edge with your chisel and give it a couple of smacks with the hammer. Eventually, the floor and rail will separate. Now do that about 120 times. Per side. I spent about 4 hours per side doing this, so be prepared. Now, I do things slower than lots of people, so maybe you'll be a lot faster.

As you remove flooring, the remnant will start to flop around. On my first (right/passenger) side, I just crumpled the metal out of my way. While this worked, I found that by cutting strips in straight sections (using tin snips) was more effective. And, ff you set them aside with the larger sections of floor you cut out, you can re-create the shape of the floor later.

Clean It Up

temporary protective paint

Once all of the spot-welded in bits of floor have been removed from the rails, you're ready to clean up. First, look at what you've done. There is a pile of twisted sheet metal lying on the ground next to your car. The rails have some holes drilled through (I know mine sure did). The rails have like 100 little circles of flooring still attached, there's some rusty spots, some paint, and probably some seam sealer. All of that needs to be taken down to bare metal for welding. Grab your grinder, put in a good grinding wheel and get after it. To me, this was the most satisfying part of the process to this point: Simply grinding away the ugly and leaving a nice clean shiny rail. Once the weld points are nice and clean, I switched over to a wire wheel and removed all of the surface rust I could find in the foot well, along the transmission tunnel and the rear, effectively grinding away all of the rust in the seating tub.

Since I was not going to be working on the project for a while, I shot the cleaned up space (including the rails) with primer and some orange Rustoleum so I wouldn't have new rust appear while I was away. This meant I got to grind that paint off later, but if you're not going to jump right into welding, I'd encourage you to consider the same.

That's it for today. More next time. Thanks, as always, for following along-