Consider This Your Warning Before Buying a Clark Cortez Motorhome!

Some people commonly fall in love with the Clark Cortez due to its retro charm; others are interested because they had fond family memories of one growing up. Regardless of why people—maybe even you—want to buy one, there is an overriding question that needs to be asked and immediately answered: Should you buy one?

We are writing a post called Is the Cortez RV Right for You? Here’s How to Find Out!, which breaks apart this question in the hopes of helping you determine your answer. However, in the quest for this answer, there is one key part that deserves the most serious discussion—so much so that the information has been awarded a post all its own. And that’s this post because this information spotlights a very large elephant in the room—or, uh, on the internet, in this case.

And as with all elephants in rooms (physically or virtually), this conversation may make you feel uncomfortable.

Because at the end of the day, no—Wanting a Volkswagen-esque vehicle for its vintage vibes or to continue heartfelt family memories is not enough of a reason to buy this antique RV.

So consider this post your warning!

You are about to take a deep dive into the heart of the matter because we are going to discuss the motorhome’s Number One major problem—and this problem is so severe it may mean you should not buy this RV …

With that said, you are ready to jump in …

---

A BIT OF BACKGROUND

Our biggest worry with our 1965 Clark Cortez motorhome is the transmission, which we often discuss because we have a constant fear of it breaking. And we aren’t the only ones with this concern. Anyone who has a Clark Cortez motorhome within the years 1963 to 1968 should have this fear—In truth, it would be foolish not to.

However, why do we describe the transmission as fragile? Here is that answer in detail …

For starters, Clark is a forklift company who briefly stepped into the RV business—and we’ve written about this historical venture in A Short History on the Clark Cortez Motorhome, but here’s a quick recap …

When Clark set about designing the Cortez, it had a clear goal in mind: to be the first purpose-built front-wheel-drive RV on the market.

At the time, nearly all RVs in America were front engined and rear wheel drive so this new design would offer several advantages over the competition. The first advantage was the Cortez did not need additional components, such as the prop shaft, rear diff, and axles. The second was the Cortez could have a lower floor. The last and third advantage was a front-wheel-drive layout weighed less, giving the Cortez better gas mileage, which in turn made it more efficient.

While all sound great, there was a major issue—At the time there was no suitable front wheel-drive transmissions that would work in the Cortez due to the available space, vehicle weight, heavy-duty capability, and engine compatibility. To overcome this, Clark set pencil to paper and designed their own four-speed manual transmission. 

“Wonderful!” I hear you say. We even thought so at first too. Since then, we’ve since become wiser …

Turns out, this unique transmission has a reputation for breaking so much so that — over 50 years later — it is the Achilles heel of the Clark Cortez.

---

FOUR DELICATE TRANSMISSION PARTS

Looking specifically at what breaks, there are four transmission parts that would be crippling to the Cortez if they fail. To make sure you understand the gravity of this situation, let us repeat this: We are not talking about one transmission part that can fail but four that are known to fail. Here’s more …

The first part to cause problems is the clutch release bearing (also known as the throw-out bearing). This bearing is part of the clutch system, and it disengages drive from the engine to the transmission when the clutch pedal is pressed.

If this fails, the bearing stops spinning and gets extremely hot, which damages the clutch. However, even if the clutch is repaired, the worse news is it is nearly impossible to find another clutch release bearing today. (And if you were graced by gods, as we were, and found one—expect to pay an extortionate price to get it. For instance, instead of an average of $30—70 for this spinning metal ring, we paid $140, which is shocking for what the part is.)

The second problem involves the transmission casing. The transmission casing encloses (or houses) the transmission so it contains the transmission’s gears and oil. There are several cases of the casing cracking while driving. Depending on the location of the casing crack, transmission oil can leak out. From here, one of two situations can occur …

Situation One: The leak is not noticed and corrected quickly, so oil drains out. When this happens, the transmission will run dry and overheat. Without lubrication, the gears will seize, and the transmission is destroyed.

Situation Two: The leak is noticed, but fixing the issue is tricky and laborious. To do this, the cradle has to be pulled from the RV, the transmission removed and pulled apart, and the casing cleaned and welded. Providing nothing else is damaged, the transmission then has to be reassembled, reinstalled to the cradle, and refilled with transmission oil before the cradle is reinstalled back under the RV. Looking at the first step alone (pulling the cradle from the RV), we speak from experience (multiple times) when we say this job alone is one we would both rather avoid at all costs.

Moving on, the third and fourth transmission parts that can fail are the known main weak spots. They are the pinion gear and ring gear, and they work together to assist in reducing speed and amplifying torque or changing direction of motion.

The pinion gear has a seven-toothed shaft, which means the shaft has to turn five times to fully rotate the ring gear once. This ratio leads to more stress on the pinion gear. Over time, if the driver is heavy on the clutch or throttle, the shaft can break. It is also nearly impossible to find another pinion gear today.

Looking at the ring gear itself, it is held in place with twelve mild steel rivets so, again, by heavy clutch or throttle use, these rivets can shear. If this happens, they then bounce around inside the transmission until they get caught in other gear teeth.

To end, all of this can cause serious damage inside the transmission. Being ‘lucky’ in an unlucky situation means the rivets sheared when setting off so the speed is slow, the problem is noticed immediately, and the engine can be quickly turned off. Still, the cradle will have to be pulled from the RV, the transmission removed, the gear ring taken out, and all of the broken rivet bits found. High-quality nuts and bolts will have to be purchased (Others have used Grade Eight zinc-coated or titanium) followed by the ring gear reassembled and reinstalled before the cradle is reinstalled to the body. Keep in mind this is the ‘best case’ scenario too. What is more likely to happen is the rivets will shear while driving, and chaos will ensue inside the transmission.

Overall, these delicate parts come together to create risky problems. Here’s the main catch though: We aren’t even finished because this equates to the biggest news yet …

---

TRANSMISSION AS A WHOLE

Along with no alternative transmission parts, there are also no alternative transmissions for replacement.

This means even if you gave up finding individual transmission parts, you cannot simply Google “Clark Cortez transmission for sale” with expectations of ever finding a complete transmission. Remember, the last time Clark manufactured a Cortez transmission was in 1968 … and the forklift company has no information on the Cortez motorhome today. (Believe us—Calls have been made several times).

Therefore, what does this mean for you if you have bypassed our warning and are still steadfast in owning this rare vehicle? We won’t be the bearers of all bad news. There are a few options …

---

CORTEZ OWNERSHIP OPTIONS

The transmission worries we point out affect Clark Cortezes made in the years 1963 to 1968. In 1969, Clark made a smart move to vastly improve its four-speed transmission design, eliminating nearly all of the concerns mentioned above. (As a side note, Clark also got rid of the three-point-seven liter Chrysler 225 inline-six engine and replaced it with a five-liter Ford 302 V8, which is more powerful so better suited with the new transmission.)

Therefore, if there is a Clark Cortez to buy, aim for the one in 1969.

Another option is to purchase the Clark Cortez’s brother, the Kent Cortez. In 1970, new manufacturer Kent took over the Cortez business and changed the transmission to a commonly available Turbo Hydramatic three-speed automatic found in an Oldsmobile Tornado. (Side note again: Kent updated the Cortez in two ways. One way was they used the Tornado’s engine, which was a seven-liter 425 V8. The other was they adapted constant velocity joints (or CV joints), which allow for suspension movement, on the drive shafts; this decision eliminated the universal joints so CV joints are far more robust.)

All of this means—even better than purchasing the 1969 Clark Cortez—the best option is to buy a Kent Cortez instead.

Still, the Kent Cortez does look different from the Clark so if you cannot part ways with the original, our last option is to retro-fit a Kent cradle, engine, and transmission to a Clark. This offers the best of both worlds—a cute Cortez exterior with a reliable transmission, larger engine, and CV joints. Unfortunately though, this is not a simple swap so be aware a Kent cradle in a Clark Cortez involves changing other components (such as the drive shafts), along with serious cutting and fabrication.

---

STAYING STUBBORN FOR THE CORTEZ

All in all, Clark Cortezes do still roam the roads so if you dismiss our counsel, theoretically if you look after the motorhome’s transmission your vehicle could continue to travel for years to come.

One main way to protect the transmission is to put aside the desire to install a more beefy engine.

Ask yourself—and be truthful—is a beast-of-an-engine more for you or your Cortez? The answer is the beefy engine is not needed …

True, some have had success with different engines over the years, but others also have not. By not installing a higher torque engine, the chance of the engine harming the transmission is decreased. One issue that is often brought up when the topic of engine swaps is mentioned by owners (or potential owners) is the increase in torque. As the original transmission was designed to work with the torque output from the 225 inline-six, any engine swap increases the load on the transmission. Driven sensibly though, often there are no issues, but the increased torque can cause havoc with the gear ring and pinion gear if the owner is heavy on the throttle.

Another way to protect the transmission is to decide not to tow. From other vehicles, boats, jet skis, and more, the extra weight puts additional load on the engine and the transmission. Again, ask yourself are you towing for the benefit of maintaining an antique RV or are you towing for your own pleasure? We can assure you the Cortez does not care if you want to enjoy water sports or drive off in a more sensible vehicle … and it will make you pay for this decision later.

---

The sad reality is Clark Cortezes will continue to disappear over time, and this is why we want to write this post.

However, with the right owners, knowledge, and time, a decision that could potentially cost the vehicle can instead spare it.