Beyond Unboxing: A Dive into the Gear Vendors Overdrive

We’re going to skip ahead a little from the Summer of Ven into more the “Autumn of Ven” because I get to ramble about a cool mechanical thing. As one of the categories on this site, I often take apart neat things and make snide comments about their construction or internal parts. This time, it will be the Gear Vendors overdrive unit that lives under Vantruck, which I got for it in 2018 in a already very well used state.

I didn’t know how many miles it had on it already, and kept up with the recommended maintenance interval for fluid changes. It was just fine from 2018 until this past summer when it began slipping under load, and even worse, would occasionally seize in the overdrive state, leaving me barely able to reverse (and you’ll see why soon). Hauling so many vans back home probably did the unit in, finally.

I tried a few hacks, like flushing the fluid with a lower viscosity oil for a little while and cleaning the high pressure filter, neither of which really resolved anything decisively. Well, that’s how things shake out I suppose, so I called Gear Vendors to send the unit in for rebuild. What they do is go ahead and send you the new one and refund a core charge once they get the used unit. The total cost afterwards is about $1200 for a rebuilt unit, $500 of which is the core charge.

I’ll get to the install itself – first is the interesting bit, which is taking the old unit apart!

Here it is on the surgery ward floor after dismounting from vantruck. Notice that the input shaft is pulled out? It’s not actually attached by anything, and all you need to do is ensure it mates with the internal spline on the right side. I’ve pulled some kind of inspection lid off already, as my MO with anything on Beyond Unboxing is to start popping bolts off.

Inside the lid is the tail end of the output shaft. There’s nothing much going on here to speak of. I think this port is to install retaining clips.

The real bolts are around the perimeter on M8 studs. They come off fairly easily.

On the front, you need to remove the four nuts that holds the shifter piston’s end effectors, little bracket things, to the internal shifter ring. They’re gently spring loaded in this position, so the studs will pop inwards as you take the M8 nuts out.

When the shifter solenoid valve is enabled, oil pressure fills the two shifter cylinders (the round things behind the brackets). These two brackets then pop outward and collide some parts together inside that they’re linked to. We know from cutaway diagrams that it’s cone-clutch based, so presumably it’s connected to the cones.

Where does that oil pressure come from? The shaft that fell out has an eccentric lobe on one end, which rides in the circular socket seen in the center. That’s connected to a simple rod pump. So when you move, there is oil pressure. When you don’t move, you pray the seals are still adequate (though it seems like one or two pumps of the rod is enough to fill up the shifter piston chambers. Typically, to prevent leak-down from causing inadequate pressure to operate the pistons, the automatic controller you can get (which I didn’t install, because fuck using phone jacks as connectors) has a speed-based lockout.

And with those bolts removed, the whole thing just kind of splits open. Well there’s my first sign of something being wrong, the clutch cone has no… clutch on it.

Here are all the fun bits laid out in order left to right: the casing with the fixed clutch ring, the cone clutch assembly, the gearset, and the output. So what in the epistemological hell is going on inside these things, anyway? They rely (as most good things do) on the magic of planetary gears and their ability to add, subtract, and multiply speeds.

So the big showrunner of this basket of skulduggery is the cone clutch assembly, pictured center left. It’s coated on the outside (usually……..) and inside with clutch lining, and is the object being rammed into everything else.

I pushed the shaft back in for the assembly photo, but notice that the shaft doesn’t engage with the cone clutch, but actually with a splined bore inside the planetary carrier (center-right). When you spin the input shaft of an assembled Gear Vendor overdrive that’s at rest, you are applying torque to this carrier.

The sun gear of the planetary gearset is attached to the big clutch cone. This means the clutch cone controls whether the sun gear is fixed (grounded) or free to spin with everyone else including the clutch cone itself. This is important, because on the very right is the output cup, which acts as the ring gear (asteroid belt?) of the planetary gearset. It, too, is a cone shape on the outside, fitting tightly into the interior of the cone clutch under rest conditions.

So you have two choices for the position of the clutch cone. Either it’s spring-loaded (with a big throwout bearing seen below) into the output cup, or it’s pushed against the fixed clutch ring on the casing by the shifter solenoids.

In the rest condition, the cone clutch is shoved against the output cup. They rotate as one. With the sun gear affixed to the cone clutch, it’s forcing the planetary gears to also not rotate. If you overtorque the system and overcome the cone clutch friction, there’s one more line of defense left: the planetary carrier on one side is a very large spline that fits into the corresponding spline in the output cup, around which is a one-way bearing.

Therefore, in the rest condition with the vehicle powering forward, the torque is taken up by either the cone clutch friction or the one-way bearing forcing the carrier’s torque (which is your input, remember) straight to the output shaft.

In the overdrive condition, the cone clutch shifts forward a half inch or so and mates with the fixed clutch ring on the outer casing. The sun gear is stopped dead, and the planetary gears are forced to mate in orbit around it.

The good trick here is when you have a planetary gearset in that condition, the rotational speed of the planets adds to the rotational speed of the carrier. A gear that mates with the planets, like the output cup, will get flung faster than the rate at which you spin the carrier (/the input shaft). You might say it’s overdriven. In this situation, the one-way bearing capitulates and spins freely as the output cup is now moving positively (faster, in the same direction) relative to the carrier.

So there you go. That’s how the thing works in forward. Here’s a better view of the stackup from the end view, showing the big throwout bearing that controls the cone clutch and the also-conical shape of the output cup, and its one-way bearing inside.

When using a GV unit, you’re advised to not reverse while the unit is active (shifted in OD). The automatic controller (which I didn’t install, because fuck using phone jacks for anything) has a reversing switch lockout so it automatically disengages. Also, if a unit is severely worn, reverse is also generally difficult or impossible as it slips even in the rest state. The reason this happens is a unique property of the angle of cut of those planetary gears (they’re helical cut) and the liability of having a one-way clutch.

Cone clutches work on the principle that the two cones crammed together create an outward normal force many times the force pushing them together axially. The same principle governs tapered spindles in machinery. To work properly though, you generally have to keep holding them together. If a force exists that pulls the cones apart, they’ll decouple quickly.

The helix angle of the planetary gears creates an axial thrust load when the gears are transmitting torque. The direction of the helix is very important here. It turns out, by observation, that the helix is purposefully set to 1. Pull the clutch cone tighter in the OD and forward-torque condition, as well as 2. failsafe in the off (rest) position.

In the overdrive position, with the input shaft applying positive torque “Forward”, the helical thrust force pushes the sun gear into the clutch cone, which forces it more into the fixed clutch ring. That is, to the left in my explosion photo. It took me a while of staring to realize this is the case, and it makes the engagement more solid: As long as you’re applying drive torque, the system will tend to keep itself engaged.

Reversing in the overdrive position is a problem, because now the thrust force is pulling the clutch cone away from the fixed clutch ring (Towards the right, in my first exploded photo). At this point, you’re fighting the oil pressure in the shift pistons. At low-to-no speed, the oil pressure is not high, and likely leaking down slowly. The applied reverse torque at standstill wins, the cone clutch begins disengaging from the fixed clutch ring, and you don’t go anywhere fast while slowly grinding the clutch down. In real life, this is manifested as a really ugly squealing sound as you only maintain roughly idle speed in reverse, if at all.

Oh yeah, that one-way bearing isn’t helping you in this case either, because if you’re spinning the planetary carrier the wrong way, it doesn’t engage.

In the rest position, however, with the clutch cone now forced against the cone of the output cup, reversing torque now turns into thrust load which shoves those two cones together. The one-way bearing still doesn’t help, but at least your system is trying to be in a positive-feedback state. The reversing torque is still ultimately limited by a 3/4″ wide clutch band, and if this band becomes too worn or disappears, you could lose reversing power entirely. However, the general story seems to be it’ll try its darndest even severely neglected going metal on metal, because of the thrust of the planetary gears helping keep the cones together.

So there we go. Quite a clever mechanism with a few foolproof design choices to improve overall reliability. If the helical gears were cut with the spiral the other way, everything would have sucked more. That’s easily something I see myself doing, so good thing I didn’t design this thing, huh?

Alright, I’ve satisfied my curiosity and am now ready to put it back together so I can ship the unit back to Gear Vendors. I dunno what it is that I did, but I can’t quite get the thing to close again.

So I just left it halfway open, put the nuts and washers in a baggie, and left a note explaining myself.

That’s all for this episode of Beyond Unboxing! The installation of the unit itself will be covered separately as the Summer of Ven progresses.

The Summer of Ven: Spool Bus Rising

Picture this. You know how the story goes, you get a phone call weeks after an absolutely mind-blowing raging party where you retained zero knowledge of the priori and posteriori events and CONGRATULATIONS! She’s pregnant. Ah, fuck, commitment. How many decades (if not centuries?) of movies, books, records, TV shows, and other forms of male-catered media have intertexualized this classic trope?

See, I have a very quick turnaround time for this feeling, because all I have to do is look out the window the next day and go Ah fuck, commitment. Time to get dressed and return the U-Haul trailer before you get charged for another day. And worst of all, it has to get off the street and who knows how feasible that even is. Wouldn’t it be nice if you thought about the consequences of your actions every once in a while?

Luckily, as the preamble tale would tell you, Spoolbus was purchased running and driving (albeit not stopping), so it was able to get into the yard all on its own and only barely not plowing down the row of hedges that are definitely not mine to run over.

Let’s be upfront about it: This thing is a PILE. In fact, the worst I’ve ever dealt with, and after scraping mold out of Sadvan (as well as the intervening half dozen or so extractions of future project piles for friends) I do believe I have seen some piles. Shown above is just the start of what I have to deal with, mostly miles and miles of redneck coathanger wiring and niche species of fuses bypassed with bullets.

Spoolbus also had an unusual amount of rust on it, in places I haven’t seen before on the Econoline. My reasoning is that because it spent most of its working life in and around the Charleston, SC seacoast area, it’s just as bad as being around winter road salt up north.

But the rust hits differently: as opposed to a northern vehicle which starts rotting out where salt water hits the body/frame and builds up, such as the fenders and wheel wells as well as lower body seams, being around the ocean just causes it everywhere.

The miasma of salt is constantly there, so the less galvanized/coated metals start letting go first. Vantruck exhibited this with the rain gutters being completely nuked and some other portions of the body sheet metal needing patching work, and from its history of hanging around the Pacific Northwest and California beaches, it makes quite a lot of sense. The frame is pristine, of course.

As is the frame and driveline parts of Spoolbus. Then I pull the carpet up and get this bullshit:

I learned early on that this is a favorite place for this generation Ford van to rust out, as water tends to pool here by the doghouse seam – there’s a raised lip for the doghouse to seal against, and any water has to evaporate away. Add in a leaking windshield, or the windshield frame itself having a hole rusted through, plus or minus some sloppy work boots, and this area will never dry. Murdervan also had a transparent floor.

Luckily there are plenty of fixes for this very common issue, and now having deconstructed more than one of these, I’m no longer dreading the future, just disappointed while raking the area with a shopvac to at least get the crumbs out of the carpet.

Back to the wiring, though. LOOK AT THIS BEAUTIFUL WIRING.

I swear this is every r/JustRolledIntoTheShop redneck wiring trope all in one vehicle. You have things stuffed into fuse blocks, fuses made of wrapped up aluminum foil or literal coathanger wire, wires just shoved into each other, wire nuts, vampire clips… this arrangement made Vantruck’s wiring cancer seem like a new-age counseling session.

Honestly, being presented with this was not shocking or rage-inducing in any way. Why? Because I already know I’m not fixing it, I’m replacing it. When it comes time, I’m only going after it with flush cutters and not looking back. That makes it easy to compartmentalize and set aside for later.

So why does this thing have so many random wires? It first and foremost has a lot of aftermarket instrumentation, which I’d like to bring back online more controllably one day. It has (had?!) readouts for exhaust gas temperature, oil and transmission temperature, a tachometer which these vans never came with, and a boost gauge.

As it was a hotshot/delivery vehicle, it makes sense to have these monitors present as the stock diesel E-350 of the era would have come with precisely none of those. I mean, not that any of the gauges were working…

It even continues under the hood, which is where Centurion put most of their aftermarket power feeders. The best part of it is that everything was dragged through holes drilled in the firewall with zero bushings, loom, tape wrap, or anything.

Just wires, poked through 1/4″ holes blasted in with a regular drill that was probably dull (because the metal is still all there, just rearranged on the other side where you don’t have to look at it).

The interior is completely and utterly stripped. I don’t know when this happened, but the seller (and its previous owner before that, whose name is on the title still!) said it was already gutted when they had possession. The few panels that remain seem to be ‘There was an attempt” jobs at retaining some semblance of civility.

This is, again, a mixed blessing. This gives me the most “creative” control for reinstalling an interior for sure. But I DON’T WANT THIS CREATIVE CONTROL. The only thing I can really plan on right now is it’ll get the same rear utility frame I whipped up for vantruck to remount the seat bed. I’d need to figure out a way to correctly trace patterns to construct any new interior panels. This is something that I definitely have not put any firm thought into, but luckily I’ve made enough friends in the automotive sphere that I can likely find an upholstery or interiors person to consult with. I might even start with gutting another trashy conversion van.

Moving around to the back, the step-n-tow bumper was haphazardly welded to the frame and rear cross member through a network of C-channels and L-angle irons. One of those welds was broken, resulting in Ass Sag Syndrome seen above.

Luckily, the trailer hitch below it is a solid (….but still welded) piece. What I’m trying to say is, the entirety of the back of Spoolbus is a single weldment and technically impossible to repair or replace without cutting all of it off.

It’s in good enough shape overall, though, that I think I can just repair the broken weld, therefore relevelling the butt.

You can’t really see the scratches left over in the nameplate, but it says February 1st, 1984. The serial number though is indecypherable with conventional oblique-lighting and contrast adjustment approaches. There might be a better way to pull that put later, but I was more focused on….

“It should need a brake line”

Remember, all van ads are lies. If it says it has a little rust, expect the floor to be missing and bottom panels flapping in the wind. If it says it just needs a fuel pump, replace the tank, pump, lines, filters, and unicorn farter carburetor before trying to start it.

If it says anything about the brakes being bad, prepare for a COMPLETE SHITSHOW when you dive under. Remember, this was sold to me as “It should just need that front brake line redone” well guess what, the front brake lines were fine.

The caliper and pads though? Yikes. I’m starting to picture what happened now. Spoolbus likely went through a last Traumatic Braking Event before the owner/operator(s) decided it was too spent and beat up to repair. Then it was sold locally to the previous 2 owners as a project, whereupon nobody had the time (or lack of humility) like me to actually go through 30 years of fleet wear and tear to work on it.

There’s a possibly the left caliper was seized or sticky anyway, as the right side was ONLY metal on metal. You know, at least still looking like it didn’t reach the sintering temperature of the iron.

The left rotor itself was also cracked on one face, luckily not all the way through. These are rotors that weigh something like 25 pounds each. It definitely tried to stop something very large, for an extended period of time, then sat still at the bottom of the hill. That’s the only way I can see rotors of this magnitude cracking.

Anyways, as I mentioned in van posts past, my requirement is 1. Run good, then 2. Feel good, and only then 3. Look good. Therefore, I barely care if it can go, but I need it to stop. My first challenge was to rebuild the braking system, possibly up to and including the hubs and bearings also. Might as well inspect all of the suspension parts while I’m at it.

Getting a better look now in the daylight once the weekend rolled around. These calipers are strange – they’re from before a generation break in 1985 in which Ford switched to a different mounting system. They’re captured in these somewhat-precision ground right-angle dovetails on each end and kept in place by a key pin. It almost reminded me of a motorcycle or go-kart disc brake caliper.

Check out the little “landing pads” I made for jackstands out of spare workbench OSB – because Spoolbus has to live outside in the grass/dirt area next to the garage, there’s no good way to lift it up without something to distribute the ground pressure. At first I used some spare aluminum bars on hand, but after they bent and I realized I no longer had useful aluminum bars as a result, I decided to resort to Nature’s Carbon Fiber en masse.

The little key thing on the bottom (of each side) slides (hammers, chisels) out towards you. This took a lot of effort to release, so I expect that this caliper was well seized long before the Traumatic Braking Event anyhow.

Yeah, that’s not gonna a simple thing to just rebuild. I found you can get rebuild kits for these calipers that have new pistons and seals, but why?

My conundrum was therefore the following: Just get replacements of the pre-1985 calipers and rotors which seemed to be both equally more pricy, or consider swapping the front suspension out to something more modern. The “Twin I Beam” crossed dinosaur arm suspension was used without much changes all the way up to, uhh, today. Even something post-1985 would at least let me share parts with Vantruck, which was the ideal case.

So before I ordered parts, I decided to take a run down to the local you-yoink-it yards to inspect the underside of post-1992 E350 vans. I found that there was a compatibility break in 2008 with the Super Duty style refresh when the radius bushings changed from longitudinal pointing to more conventional looking swingarm links. Other than that, the fitment differences appeared to largely be hardware size.

It felt awfully plausible to just front suspension swap, so I decided to try taking said front suspension apart. After all, I’d want to learn how to do this anyhow. That’s the upside of having multiples of the same vehicle, you feel less bad turning one into a heap (that you can hopefully put back together…) in the interest of working on them all.

And so I began taking the thing apart. Next post will cover how this went and the final decision about the front brakes!