Showing posts with label poly. Show all posts
Showing posts with label poly. Show all posts

Tuesday, June 29, 2021

Zed Body Progress

With the weather shifting warm to cold to warm again, Zed (the 1979 280ZX) work has been a little bit on-again / off-again. With the weather returning to hot for what looks like the Summer, I shifted efforts back to Zed from the other projects (you've seen the posts)... well, until this past weekend when everything came to a complete stop due to the record-setting high temps (over 45*C / 113*F). Today's post focuses on Zed's body work again, solving for the missing rear bumper and getting after some priming. Again.

Bumpity Bump
A lingering question for Zed was how to solve for the rear bumper. The original was a rusted out mess, and donorZed was about as bad. I was considering how to construct something one-off custom, but decided that an off-the-shelf fiberglass kit was a better looking, and fastest-to-implement approach. Rather than just do the rear, I got a full kit, so the front-to-back is consistent. Of course, this will delay the paint a little bit, as I have more body panels to solve for. Plus there is the added delay introduced by shipping. Ultimately, Zed will look better, so it's worth it. The kit I ordered looks like the one pictured on the side here, without the big wing on the back. That's not my style, but everyone gets an opinion. Later, I will add louvers to the rear window since that window lets in a ton of heat in the summertime if left uncovered.

In order for the rear fiberglass to mount, I needed the rear bumper bar that sits inside the big rubber ugly. I reconnected with the local Z parts-hoarding-guy to whom we sold donorZed and bought a rear bumper bar, and mounts... for about 1/2 what we sold the entire donorZed to him for. Funny how this all works. Perhaps, in retrospect, I might have saved the original rubber bumper support bar and mounts. Anyway, next was clearing the rust off the bumper mounts, and getting them ready for action. I used multiple passes with Naval Jelly followed by a coat of Eastwood Rust Encapsulator and then a coat of rattle can primer. I will shoot these with the hinges and other tiny bits that we want the color of the finished body.

Following that, I removed the front bumper support (4 16mm bolts each side) and the bumper from the supports (4 14mm nuts each side). Next, I wanted to remove the rubber ugly wrapped around the bar so we were ready for when the fiberglass kit arrives. The Phillips screws that hold the ugly cover on, however, were rust-locked in place. Multiple passes with the Kroil didn't allow them to budge. So, I had to grind them off. It is interesting how much rust was on the bumpers and how little the rest of the car had. Those front bumper mounts had virtually no surface rust on them while the bumper itself had been impacted. These mounts will also get the color spray with the other bits I mentioned above.

Prime Time
Last, I finished enough of the Bondo cycle to feel that I could lay another round of hi-build primer. The Bondo-cycle took an awfully long time, and I got far too into it. I imagine I still missed a bunch of things and it still will not look as good as a real pro paint job, but at some point you just have to stop dicking with it and go. Otherwise, you will never get to enjoy the fruit of your labor. It's just labor. I am enjoying the heck out of bodywork though, which I kind of surprising. My first round of high-build primer was both too light and mostly sanded off so if you are concerned that there will be this huge stack of paint layers, rest assured, that is not happening. I did have to wait for the weather to get warm and dry enough, though.

Once the weather turned warm again, I acted like the primer had not happened before: restoring the masking, vacuuming and blowing air, cleaning the snot out of it, etc. so it was ready to get primed. Then, I laid the body panels out under the car-port cover again and repeated the multi-passes of primer, just like I did last Fall (See Zed Prime), with a few differences. My set-up this time did not include the in-line line drier nor extra pressure regulator. I had not gotten another disposable line-drier, and without it, I could not attach the regulator. So, I set up my pressure with test fan blows on one of the fenders instead. Total Roadkill. I figured I could reduce the moisture if I kept the air compressor tank warm, so I moved it into the sun. Since the air around here is super-dry right now (humidity below 30%), there isn't much moisture in the air to get compressed into the air line anyway. This may sound sketch, but the primer landed fine.

As to shooting, I did a light first coat to give subsequent coats something to adhere to, while also avoiding runs or sags. The sunlight was so bright, it was hard to really see the fan, since the color of the primer was the same as the target panel most of the time. Similar to the 1st shoot, I did not meaningfully stop between coats 1 and 2: fill the cup, shoot the cup, repeat. Why? Because, by the time I got all the way to the end of the light coat, the place where I had started had sat for longer than the minimal flash-dry period, and it was warm enough to dry fairly quickly. The surfaces were tacky when I went around for my heavy pass, which, I felt, was just right.

The 2mm tipped gun got clogged about halfway through my 2nd coat. As I attempted to unclog it, I lost about half of a shooting-cup (or about an actual imperial cup) of paint: it turned to Jello. I think I mis-measured the concentration of hardener. Could it have been from the lack of an air-drier? I dunno. Undaunted, I grabbed another gun which had not been drilled out to 2mm; it was a 1.8mm tip. I did not clean it first, I just blew a few seconds of primer through it and got back to the job. Yes, that was lazy and yes it could have allowed for some shipping oil/crud into the primer. I considered all this and used the first little bit of shooting to second-coat the nose section that will be mostly hidden from view (under fenders, radiator support, eg). More Roadkill; maybe that show is a bad influence on me. Anyway, I finished the pieces I had not gotten with a 2nd coat after I shot some hidden areas. I found that the 1.8 tip flowed better, gave a smoother finish and had a more predictable fan than the 2mm drilled tip. So, I take from that either (a) I drilled the tip wrong or (b) my 21gal compressor, pressure set up, gun and material were all better suited as a unit to the 1.8mm tip. I'm not sure how you drill wrong, so I think the difference is really tied to my compressor, and it's ability to keep up with the air-pressure demand of the 2mm tip. Regardless, I will be shooting this high-build with the 1.8 tip on a very warm / hot day from now on.

Reviewing the Prime
None of these changes, including the especially Roadkill-inspired ones, appear to have made much of a negative impact on the primed surface. Quite the contrary, actually. I started setting up the first gun at 10 and finished spraying by 2. I took an hour to clean up work area and the second gun (first gun went into the garbage) as I let the panels sit for the rest of the afternoon. Late the following afternoon, after the panels had sat in unseasonably warm temps (30*C+ or 85*F+) most of the day, I did some test sanding on the mostly-hidden areas with some 320 grit paper. The primer powdered smooth very quickly. If this is any indication, then this priming session was much better than the first. Perhaps this high-build poly-primer is more temperature sensitive than the Eastwood folks indicated on their site: warmer drier days are much better. The first time around (when it got into the lower 50's*F/11*C overnight after shooting), there was meaningful stippling on the surface. This time, when the overnight temps barely got below 70*F, the surface is much less dimpled. And, it sands smooth much more easily; like, a few passes with 320 and it's smooth. Last Fall, I tried pre-warming the panels inside my garage but that had no effect: the shell which sat outside the whole time had the same little dots peppering the surface. I think the real difference was the long warm days both the day of and after shooting.

Learnings
My big take-aways from the shooting the hi-build poly-primer from Eastwood: use a 1.8 tip and an in-line drier on a warm-to-hot day when the overnight temp will not fall below 18*C or 65*F for best results. Do a quick-coat first for the next heavier coat(s) to adhere to. Last, it is a good idea to have an extra gun as an emergency fall back in case you mess up the hardener concentration and jack up your gun in the middle of your spray-sesh.

Go Forward
Next, I will be sanding the rest of the body panels. Then, once it arrives, I will be handling the body kit. At some point, there will be paint, but I may shoot a urethane primer/sealer first (once Eastwood has it in stock and ships it to me). And, of course, the body kit will probably need some tweaks and then priming. I sincerely hope I can get it all done before the weather prevents it. While the Fall rainy season is a distance away, we cannot guess whether we will be revisited by toxic smoke again, scrapping late-Summer plans. For that matter, we are having triple-digit heat waves (40*C+) that are keeping me penned inside as effectively as the smoke did last summer. 

I expect that if I have to wait too long for the body kit, I will set up and shoot the parts that will not be impacted (like the underside of the hood, the hinges, the bumper mounts, etc) so I can make some headway and save myself some shooting time later while also getting a better feel for the equipment and material. Some of this stuff may not be terribly post-able, but I will try to at least put a little message here about the work.

Thanks, as always, for following along-

Tuesday, June 20, 2017

MGB - Front Suspension Refresh (Part 3)

I'm continuing the front end rebuild I started in Parts 1 (See MGB - Front Suspension Refresh Part 1) and 2 (See MGB - Front Suspension Refresh Part 2). At this point, the front beam is stripped and removed from the car. We've evaluated the parts, and made determinations about which to keep and which to replace. Today starts the work of putting it all back together again. WooHoo!

Pivot on the Swivels
There some things really are best left to a shop. I want to do as much as I possibly can myself, but it's not a religion. It's just a strong preference because I want to learn and because I find it fun. I read through the process for removing and replacing the king pins and bushings within the swivels (wheel assemblies). This requires a shop press, which I don't have nor do I have the space for, and a trained eye for determining the viability of the wheel assembly as a whole. So, I contracted the fine folks at British Auto Works to do it. Like so many things, I expanded the job from just swapping the king pins and bushings to also include replacing and grease-packing the wheel bearings. Doing the wheel bearings didn't really increase the cost, and it gave me the peace of mind that the entire front end had been updated. British Auto Works completely strips, and then chem-tanks all of the wheel assembly. after testing and measuring everything, they assemble the wheel and finishes the job with fresh paint. All told, it took them three days, and most of that was because they wanted extra time in the chem-tank. The finished product looks fantastic and delivered that piece-of-mind that they were properly done.

Paint
While the swivels were at British Auto Works, I started working on the beam. For being exposed to the elements, and road debris for almost 40 years, I would have expected more damage or rust. In truth, it was in pretty good shape. So, I cleaned it up, first with a power washer, then by hand with Simple Green. Once cleaned, I could see a few scratches, but it was in really fine shape. I threaded the rusty old bolts which held the front shocks back in. I did that so paint wouldn't gum up the threads. Then I sanded it, wiped it down with mineral spirits and shot it with high-gloss black paint. Since I had the time, I let the paint cure for a week, light sanded it, wiped it down and shot another coat. At this point, I removed the old shock bolts so the paint would cure without them. While I had the materials out, I cleaned up the spring pans and springs, sanded and painted them too. Truth be told, I had lots of other parts around that I intend to re-install, so I cleaned them up, sanded, wiped and shot them too. I'll share some of the tear-down and re-assembly of those things in other posts. Everything got high-gloss black except the springs. Those I shot burnt orange which from afar looks like the vermilion on the body, but its not an exact match. I decided it wasn't a deal-breaker so I also sanded, wiped and shot the underside of the frame where the front beam mounts to it. I figured I wouldn't have that exposed again any time soon so why not?

Beam Me Up
Once the paint has been shot and cured, I was able to start assembling things. First, was the re-install of the bare beam. Since I was working on this by myself, this was a great deal harder than the removal. Why? The beam is held on with 4 bolts. Each bolt has a nut on both ends, and it passes through 2 poly/graphite (or rubber of simply poly) bushings, one on either side of the beam. The drawing on the side, here, with parts labelled 1 through 7 show the front bolt. The rear is similar. Note the orientation of the bolt in the drawing: the lump is on the bottom. This is important since the thinner stretch of the bolt runs up into the frame. If you try to send the lump up, it will not make it through the frame. Yes, I did try it that way. If you're doing this on your own, I fumbled my way into a process that works:

Get the beam onto your jack, and roll it under your front bumper. Looking from above, roughly align the rear of the beam with the rear frame holes, but still a few inches below it.
Pick a side. It doesn't matter which. Take the shorter, rear bolt, and load the bolt, stacking from the bottom: nut, plate, bushing. twist the nut onto the bolt a few turns. Slide the bolt up through the rear hole from the bottom of the beam, placing the top bushing onto the bolt. I found that these bushings sort of held the bolt in place.

With the bolt held in with friction, get more precise with your alignment, but just worry about that one hole and bolt. Raise the jack and re-check. Repeat until you have the bolt and hole lined up. Then, while holding the bolt to the beam, raise the jack, pressing the bolt into the frame. Once the bolt peers through the top of the frame, put the top nut on. Again, thread the nut on just a few turns so the bolt can hold the beam, but there is still a couple of inches between the top of the beam and the bottom of the frame.
The one bolt creates a pivot point so you can align another hole. I did the other rear bolt, following the same routine. With the rear bolts loosely in, the fronts are much easier. Stack the front bolts again from the bottom: nut, plate and bushing. Set the upper bushing, and set the bolt through the frame hole. Thread on the top bolt.
Now you can start tightening the nuts. On all 8 nuts you want some threads to peek out from the nut. If you don't see threads, you may not have enough bite on the nut to withstand the pressures during intense driving. Then, torque to spec (54 to 56 ft/lbs).

Shock Me
Once I had the beam in, I shifted to installing the front shocks. If you remember, the removal was only difficult for the rear bolts because of how close they are to the wheel well. The install is also challenged by this. If you painted your beam, did you paint with the bolts out? I accidentally left one out: the one I took to the hardware store. That bolt hole was a real pain to get a bolt into at this stage. The others just took a little windex on the bolt, and it threaded right in. Once finger tight, it doesn't take much to torque it down... except getting a torque wrench in there is impossible. You'll need to feel it, as you're aiming for 43 to 45 ft/lbs. I actually came back and torqued after I did the lower control arms because the torque settings are so close, I got a good feel for what 45ft/lbs is supposed to feel like.

Lower Control Arm
Now for the fun part. Whether you bought new arms or cleaned up your originals, there are two different arm shapes: one for the rear and one for the front. The "front" has a hole specifically for the sway bar that's reinforced. Pick a side. Grab a spring pan, three sets of spring pan fasteners (1/2" nut-washer-bolt combinations) and your lower control arm bushings. If you got the fender washers like I did, grab them too. You don't need the lower trunnion kit nor the spring yet. On each arm, press in the bushing. If you got the poly bushings, this may require a press. The rubber and poly/graphite fit in without much difficulty.

Slide a fender washer onto each front-back side of the pivot (the thing on the beam that the lower arms attach to). Then fit the rear and front arms on that same side, making sure to have them pointing towards each other and making sure you're using a front and a rear arm in the right spots (rear on rear, front on front). Yeah, that sounds obvious and all, but once you get on the ground all those arms start to look the same. Consider that the flat side on the arm faces the pan (see the picture).

Let the arms hang down and grab the spring pan and one set of fasteners. Holding the pan with the dish facing towards you, lightly thread the bolt through from the outside of the arm through to the pan. Set a washer on the bolt and then finger a nut onto the bolt. Do not tighten yet. Do the other 2 fastener set the same way: 2 on the rear, one on the front. With the spring pan loosely held to the arms, slide the other fender washers on and follow with the castle nuts. Once everything is on, but loose, start tightening things, moving from castle nuts to spring pan fasteners so no bolt gets hung up because it has been left untouched for too long. When everything is snug, torque to spec: 22 ft/lbs for the spring pan fasteners and 45 ft/lbs for the castle nuts.

For the castle nuts, align the castle with the cotter-pin hole and put in the cotter pin (or bailing wire, if you're like me). Better to torque a little too much than not enough, IMHO, but you shouldn't need to go higher than 50 ft/lbs. If you do, re-check your work. Maybe something is hanging up.

That's it for this time. I should be able to finish this up in just one more post. I'll get the swivels and springs on, and then the major efforts are completed. Thanks for following along. This has been an incredibly rewarding effort.

Tuesday, June 13, 2017

MGB - Front Suspension Refresh (Part 2)

Continuing from my last post, I'm focusing this group of posts on the rebuild of the MGB front end. Today, we get down to the beam, and get it removed from the car. I'll evaluate parts, and talk about replacement bushing options. Part I can be found here.

Shocking
While the beam is in, and you have access to your front shocks is the best time to evaluate them. On the right side, the shock responded relatively well to my efforts to move the arm up and down. It resisted in both directions, but not as much as I would have liked. Still, I probably could have left it alone. The shock on the left (driver) side, however, offered virtually no resistance to my attempts to move it. In fact, I could push it to the top of it's motion and it would slowly drop down. That shock is shot. Suspension shops usually recommend replacing both fronts and/or both rears at the same time. For a front-end like this one, where the shock absorber is also playing the part of the upper control arm, it is all the more important. These are held in place by 4 bolts. The two against the inner wheel well can be difficult to get to, but you can address them with the most basic spanners and ratchet/sockets. Similar to the engine mount replacement (see MGB - engine mounts), a good supply patience is welcomed here.

Set the shocks aside with the lower arms and pans. To protect the threaded holes, finger the old bolts back into the holes. I took one with me to Orchards and found replacement grade 8 stainless steel ones for the reassembly. I strongly recommend replacing fasteners with stainless steel or zinc coated to reduce the rusted-on effect.

Beam Down
image swiped from 'net,
but that's a stock beam
Now, the front beam should only be connected to the car by 4 bolts. Nothing else should be tying them together. No brake lines, steering bits, etc. but it never hurts to stupid-check (so-called for those moments when you don't check, something bad happens and call yourself stupid for not checking).

I used an ATV / transmission jack, but a more standard wheeled floor jack should work; it will just take more patience with balance. The ATV / transmission jack is nice in that it has two long arms to spread the weight, and improve the balance. Still, with the front end way in the air, and the rear on the ground, the bottom of the beam is not parallel to the floor. So, I slid a 2x4 under the front of the beam when the ATV / transmission jack reached the underside of the beam to make uniform contact. Raise the jack until it is holding some weight, but not much. You want the car stable on it's jack stands.

Relieve the torque on the 4 bolts by cracking the 4 bolts on top. you shouldn't need to hold the bottom nuts at all for this. I used the breaker bar with an assortment of extensions. Once cracked, do the same on the bottom nuts, just so they are not rusted in place. Whether you remove the nuts on top or the bottom or a mixture doesn't really matter. In the end, all 4 bolts need to be un-nutted on both ends. You would think that once the nuts have been removed from the bolts, they would just fall out. Fat chance. How about lowering the jack a little bit? Nope. To free the bolts, the top nut needs to be removed. Then, using a socket extension so you can address the bolt, rap the bolt from above with a rubber mallet. When this doesn't work, use a framing hammer, but be very careful with those bolts. They are not normal and if the threads are damaged, you'll need to order new ones.

Once the bolts fall out, either through banging or playing with your jack or maybe you got lucky and they just fell out... you'll see that these bolts are 2 different lengths and that the longer bolts (that fell out of the front) have a lump in the middle like a poorly rolled spliff. I retained all of this hardware, choosing to not try to find replacements, though I thought about it. Simply lower the jack, and the beam will lower with it. Pull out the front under the radiator and bumper.

Parts and More Parts
At this point, I was pretty spent. From the start of the prior posting to the beam on the ground was at least 2 days. Now that I've done it once, though, I could do it again in 1/3 of the time or faster. As I set with a beer, I looked at the pile of parts and the zip-lock baggies of fasteners. The fasteners were all bare steel, and they had plenty of rust on them. I chose to replace all of them except the beam-to-frame nuts and bolts. I added 4 fender washers to fit between the beam and the lower control arms. I felt this would help the bushings last longer. The fasteners probably put me back $50. Then, I turned to the pile of parts:

front shock absorber /
upper control arm
Front Shock Absorbers (2) New, these are crazy expensive. Moss has them for over $330 each. Instead, I found World Wide Auto Parts in Madison, WI who rebuilds originals. After some research I bought a pair from them at $99 each plus core which was returned when I sent my old ones back to them. They really look great, and if they work as well as they look, I just may go back for replacements of the rears instead of doing the swap-out for non-MGB rear shocks that so many folks do. The paint chips off without much effort, so if you're going for a show-car experience, I'd recommend repainting them.

Lower Control Arms (4) These looked okay, but without tight tolerance measuring tools, I couldn't tell if any of the important holes on the ends were out of round. Replacements for all 4 was $70 with OEM British steel, and the originals could have been worn from the bad seals, so I coughed up the $70.

lower control arms
Spring Pans (2) Like the arms, I couldn't tell for sure if the mounting holes were out of round, but on very close examination none of the holes looked oval. Since no pivoting happens with these pan holes, even a little out of round probably wouldn't matter so I chose to keep the spring pans, and just clean them up instead. New-steel replacements are $32 each at Moss, so they're a little steep cost-wise compared to some of the other bits. Still, if the spring pan won't firmly attach to the arms, your suspension won't be safe, so spend the $64. In the end, there was 0 play after everything was put back together, so my assessment was correct.

Front End Rebuild Kit (1) This was the whole point of this work. I found a few different suppliers for this kit, and resolved to buy from British Parts Northwest for $120. While their return policy is crap, their price is $35 less than Moss. These kits include:
- king-pin set and bushings. These run vertically between the arms and through your swivels
- upper control arm nut/bolts. They call them "fulcrum pin and hardware" and they attach the top of the swivel to the control arm / front shock absorber.
- upper control arm bushings (rubber or all-poly). These pair with the upper control arm nut/bolts to complete the set. I ended up swapping out the kit-supplied ones with some Poly/Graphite bushings I got from a new friend, Basil, in California ($6)

- lower control arm to swivel bolt/nut and bushings. They call these "Lower Trunnion Kits".
- lower control arm to beam ("A-Arm") bushings and bolts (rubber or all-poly). Again, I went with Poly/Graphite ($20) from Basil instead of the kit-supplied ones.

To do the front end rebuild, that's really all you need. I decided, though, that as long as its open, replace the beam-to-frame bushings.... and the sway bar bushings. Again, I sourced these from my friend in California. frame bushings ran $23 and the sway bar bushes were $10. When I consider there was no extra labor for the beam bushings, and very little on the sway bars, this was a very low cost to get the front end as rock-solid stable as possible.

Rubber, Poly and Poly/Graphite
Just for an aside, I wanted to touch on the differences between these three types of bushing. As a general rule, it's best that you pick one and stick with it through the front end. Since they behave a little differently from each other, the front end could be less predictable if your lowers and uppers are not the same material and respond to stresses differently.

Rubber - this is what you had originally. When squeezed between two pieces of steel which want to twist, the rubber twists with it. This smooths out the twisting motion, giving an easy, forgiving ride. For a cruiser, this is great material.


beam to frame bushings
Poly - this is the more common "upgraded" bushing. Unlike the rubber, the poly does not twist with the steel; it resists the twisting motion. This resistance reduces the degree of the twist, allowing more of the force through to the ride. This is a much less forgiving ride, but gives you a much stronger "sense of the road". Installing these bushings can be very difficult, requiring water-based lube or other tricks, maybe the use of a shop press. Once installed, most owners report loving them.

Poly/Graphite - this is in-between the Poly and Rubber in terms of road feel and difficulty of install. Basil described this far better than I could, so I will quote: They look like black plastic that has some give to them. You can put one between your thumb and forefinger and feel it give a little. The polyurethane matrix has a slippery substance called "graphite" (a crystalline form of carbon) in the polymer matrix so a slippery bit is always exposed and thus self-lubricating the bushing. No special install efforts needed.

This post got long again, so I'll continue in another post. At this point, we have the front beam completely torn down, our parts are ordered, and fasteners sourced at the local hardware store. We'll start next time with some painting and then assembly. Thanks, as always, for following along...