The following write-up is a brief introduction to the Vanagon transaxles. It covers how they work (in layman's terms) and draws some comparisons between the 3-speed automatics and the 4- or 5-speed (yes 5!) manuals.
Vanagons have transaxles. A transaxle is a transmission and a final drive assembly (also referred to as a "differential," "ring and pinion," "rear end," or "third member") put together into one unit. The transmission section does the shifting part. The final drive section is a gear reduction device that also changes the direction of motion of the transmission shafts (in-line with the crankshaft, which is oriented length-wise in the vehicle) into the motion of the wheels (in-line with the drive axles and wheels, transverse-wise in the vehicle). For now, we will just refer to the whole thing as a transmission.
"Why do vehicles need a transmission? Why can't you just have one gear?" My daughter Clara asked me that one day when she was 8. Anyway, the reason is that the engine needs to run at a particular speed range to produce the needed power to propel the vehicle, irrespective of vehicle speed (what did he just say?). Vehicle speeds vary from zero to whatever maximum speed may be, in the case of a Vanagon let's use 100 mph (yea, sure, off a cliff maybe). Anyway, even though the vehicle is traveling from zero to 100, the engine speed never drops below idle (about 1000 RPM) or above "red line" (about 5500 RPM). Indeed, the usable engine speed is more like 2200-4800 RPM. In order for this to take place, a transmission is needed. Each speed of the transmission allows the vehicle to run at a particular speed range. First gear is good for speeds up to about 25, 2nd up to about 45, and so forth. Automatic transmissions and manual transmissions do the same thing. One requires manual shifting, and the other is automatic, but they both have gears or "speeds". In a perfect world, there would exist a transmission that would let the engine rev to its most efficient speed (about 3800 for a waterboxer), regardless of vehicle speed. Such a transmission would allow you to hit the gas at a stop sign, allow the engine to rev up to 3800 RPM and hold it there as the vehicle's speed increased. Modern electronically controlled 4 and 5 speed automatic transmissions (when they work) closely achieve this. It's almost eerie to drive one of these modern vehicles, and accelerate through the gears with engine RPM varying by only a few hundred units, while the vehicle accelerates from a standstill. However, this is not a perfect world (just ask anyone with a Eurovan who has had to replace their 4-speed electronically controlled transmission at, say, 40,000 miles!), so the VW Vanagon was offered in the USA in either a 4-speed manual or 3-speed automatic.
There are some performance differences between the 4-speed manual and the 3-speed AT. The advantage of the 4-speed is that, since it has four speeds instead of only three, there is more selection of engine speed for a particular vehicle speed. Vanagons with a manual trans have a top speed that is higher by about 10 mph (about 95 instead of about 85 for the AT). At 75 mph, for example, the 4-speed Vanagon will have an engine speed of about 4000 RPM, whereas a AT Vanagon will be closer to 4400 RPM. That is really the only down-side of the AT. Other than that, the AT offered in the Vanagon is wonderful. It is a very simple, robust design that VW/Audi has used practically unchanged for over 25 years, in a dozen or so different vehicle models. And, contrary to popular belief, the AT Vanagon will actually outperform a 4-speed Vanagon on highway grades, with the stock 80 hp 1.9 liter, or stock 90 hp 2.1 liter engine. This phenomenon is due to the fact the Automatic is geared lower overall, and has a torque converter instead of a clutch system. The torque converter allows some slippage between the engine and transmission, which allows the engine speed to raise somewhat at higher torque demand (what is referred to as torque converter "stall speed") without the vehicle speed going up. The manual trans has a clutch that allows no slipping at all. So, when you drive up to the same grade in a Vanagon with 4-speed and can't maintain speed in 4th, all you can do is down shift to 3rd. But once your speed drops to 45 mph, the engine speed drops below the engine's peak torque RPM, and now you have to drop down to 2nd, and a corresponding maximum speed of about 40 mph. With the AT it just turns out that when shifted manually into 2nd, you can drive at about 55 mph without over-revving the engine. So, when you get to a highway-speed hill and down shift to 2nd, you can wind the engine up to about 5000 RPM (closer to max HP for the waterboxer) and climb most grades at between 45-55 mph.
Now, when coupled to a higher HP engine, the hill climbing advantages of the AT disappears. If you have an engine that makes more torque at low RPM (like any of the GoWesty engine upgrades), you can climb that same hill with a 4-speed in 3rd or 4th (depending on which engine upgrade you choose). And, with the AT, there is no longer a need to drop down into 2nd. You can pull most hills in 3rd. With the higher HP engines, it makes it possible to drive much faster, yea, even 100 on flat ground without a tail wind! But even with the extra power, an AT will not go that fast because in doing so you would over-rev the engine. Make sense?
The Vanagon was offered in the USA in either a 4-speed manual or 3-speed automatic. Longevity is about the same for either the AT or manual (about 250k miles, except for pre 1990 manuals. Read our "Sudden Death Syndrome" article.
“But aren't automatic transmissions more costly to replace than manual transmissions?” Yes, the Vanagon AT costs more to overhaul than the Vanagon 4-speed manual (about $1800 instead of $1300), but since there are no clutches to replace in the interim, cost to own is about the same. The only other cost related issue with the AT is the oil cooler that sits on the front (water cooled models only), which should be replaced every 10 years or so just in case. When it fails it allows the ATF and coolant to mix, ruining both the transaxle and the cooling system at a cost of about $4000 (I am not making this up! We have seen some really, really long, long faces around here!). That makes replacing the cooler (at a cost of about $275 installed) a bargain indeed. If you have an AT Vanagon, and you don't have any records of the trans oil cooler having been replaced, call GoWesty TODAY and buy a new one. It can save you HUGE $$$$ All Vanagons sold by GoWesty that have automatic transmissions get NEW trans coolers installed. Period.
Now, what about the 5-speed transmission? You may have heard that some Vanagon Diesel-powered models, and all Syncros have 5-speeds. Well, kinda. In actuality, they just have a 4-speed with an extra, super low, low-gear. In the case of the Syncro it was intended for off-road use. In the case of the Diesel it was intended to get it out of its own way, albeit very, very slowly…
Stock 83-91 4-speed transaxle has:
3.78/2.06/1.26/.85 with a 4.86:1 or 4.83:1 final drive, which equates to overall ratios of (1st-4th respectively) 18.37/10.01/6.12/4.13
GoWesty 15" or 16" tire and wheel package will raise all gear ratios (and lower engine speed) by between 3% and 6% depending on what tire is being replaced. And contrary to popular belief, this change actually CORRECTS speedometer readings. The speedometer in Vanagons fitted with a correct size 14” tire and wheel actually reads to fast. Yes, you are actually going SLOWER, and getting LESS FUEL MILEAGE than your speedometer and odometer are indicating! Can you believe that!