Frequently Asked Questions
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What is a Dune Buggy?
A. There are many styles of Dune Buggies. We classify dune buggies into two basic styles fiberglass "Tub Bugs" and steel framed "Rail Buggies". They can be set up for a variety of fun applications including sand dunes, trail riding and street cruising.
Does my Dune Buggy use a VW Beetle Chassis?
A. Typically fiberglass dune buggies are based on a vintage VW beetle floor pan that has been shortened. Likewise all the controls, such as the shifter rod and control cables are all shortened to accommodate the smaller pan.
Steel framed rail buggies typically are a custom designed chassis that incorporates elements of vintage VW beetles. Many rail buggies use air-cooled VW beetle or VW bus rear torsion housings and transmissions. They also often use VW front axle beam assemblies.
What's the difference between a VW IRS (Independent Rear Suspension) and VW Swing Axle Transmission?
A. VW Beetle swing axle transmissions were installed in bugs until 1968 in the USA. They feature solid axles that connect the wheels to the transmissions. The easiest way to identify a VW swing axle is by the large (2.5") tubes that cover the solid axles. These tubes have a boot at the transmission where they flex. At the wheel there is a solid connection that houses the wheel bearing and connects to the shock absorber.
VW Beetle independent rear suspension transmissions began being installed in bugs in 1969 and were installed up to 1979. These transmissions feature a modern CV joint on each side, which is the easiest way to identify them.
Do I have a VW Bus or VW Beetle Transmission in my Dune Buggy?
A. Dune Buggies are often made up of a variety of vintage VW parts. People use both VW beetle sedan transmissions and heavier duty VW bus transmissions in dune buggies. VW bus transmissions are generally stronger and better for off road applications or high horsepower street applications.
VW bus swing axle transmissions feature gear reduction boxes at each wheel rather than the standard bearing housings that are on VW beetle swing axle transmissions. These reduction boxes multiply the torque coming from the transmission to enable a small engine to move a heavy VW bus.
VW bus IRS transmissions are a very popular transmission for dune buggies and woods buggies. They are much larger than VW Type 1 sedan transmissions. The differential housing where the CV joints bolt on a bus transmission is more square than a beetle IRS transmission, which has a rounder case that dips between the bellhousing and nose cone.
One of the easiest ways to identify whether you have a beetle or bus IRS transmission is to look at the stiffening ribs on the transmission case. A VW bug sedan transmission has shallow widely spaced stiffening ribs. VW bus transmissions have tighter spaced ribs that are typically deeper.
What are the Different Types of IRS Bus Transmissions?
A. There are three styles of VW Bus IRS Transmissions. They came in all bay window buses from 1968 - 1979. Each of these transmissions are classified by the stiffening ribs on the transmission case above the CV joint flanges. There is a three rib, five rib and six rib bus IRS transmission.
The "002" three rib transmission came in VW buses from 1968 - 1973. Typically these transmissions have a 5.38 ring and pinion ratio. They are considered the weakest of the bus IRS transmissions, but still have plenty of strength to handle a mild performance engine in a dune buggy or woods buggy with some big tires.
The "002" five rib transmission came in 1974 and 1975 VW buses. It looks distinctly different than three ribs due to its angular ribs. Three ribs have rounder contours. Five ribs have a longer 4.86 ring and pinion ratio. That keeps RPMS lower for high way cruising at higher speeds. They also lend themselves well to larger engines that can more easily spin up the longer ring and pinion.
The "091" six rib transmission cam in all 1976 - 1979 VW busses. It is considered the strongest of the stock VW bus transmissions. It features a 4.56 ring and pinion ratio, which is even longer than the 5 rib. This transmission is ideal for large displacement engines in off road machines. Although it is the strongest available stock VW transmission, keep in mind that this was designed to handle around 80 -100 flywheel horsepower from the factory.
What is a Vanagon Side Shift Transmission?
A. The 094 water cooled VW Vanagon Transmission is gaining popularity among off road dune buggy enthusiasts due to its durability and strength. This transmissions was found in 1984 and later transmissions. These transmissions have many of the same features as 091 six rib transmissions with the added bonus of a full sized reverse gear. This means they will take more abuse in reverse, when digging out of a hole or backing out of a tight spot compared to any other bus transmission. Special side shift adapter assemblies are now available from Weddle Industries and Jamar Performance to adapt standard dune buggy shifter linkage to the Vanagon side shift linkage.
Why is reverse gear prone to failure in off road dune buggy and woods buggy applications?
A. In all air-cooled VW beetle and VW bus transmissions reverse is the smallest gear in the transmission, with a diameter of around two inches. Often when people get stuck in the woods or sand when off roading they try to dig their way back out. If the wheels are spinning freely and then catch under high engine load they can break reverse gear fairly easily. Heavy duty options are available, but the best insurance is management of your right foot when in a tough spot. There's no shame in getting pulled out if it saves you a transmission rebuild bill!
Reverse gears are specific to each transmission model. Make sure you know what you need prior to ordering one.
What Type of VW Front End Do I Have?
A. VW beetles have a very nice modular front axle assembly that make them a great choice for dune buggy front ends.
The two most common dune buggy front ends come from Standard VW Beetles, rather than Super Beetles.
Early style VW bug front axles feature a king and link pin design. They were installed in VW beetles up to 1965. These front ends are preferred by many off roaders due their strength. The solid steel pivot connections are much more difficult to sheer when hitting obstacles or climbing hills. Heavy duty aftermarket spindles are also available for link pin front ends, where they are not available for later model front ends.
Late style VW bug ball joint front axles were installed in VW beetles starting in 1966. These front axles feature an upper and lower ball joint on each spindle. Ball joint front ends offer easier articulation and a smoother ride. They are ideal for street oriented dune buggies, but are often used in off road applications as well. Heavy duty off road aftermarket spindles are not available for ball joint front ends.
Are there any tricks for lowering or raising my VW beetle or dune buggy?
A. For street applications lowering spindles are available from a variety of manufacturers in both ball joint and link pin front ends. Typically dropped spindles lower the vehicle about 2.5 inches. The nice thing about dropped spindles is that they maintain your factory suspension geometry and just move the wheel's location on the spindle for a lower stance with a factory ride.
Front axle adjusters are also available for link pin and ball joint front axles. These adjusters must be welded into the front axle. Once installed they allow you to pivot your torsion bars up or down to raise or lower the vehicle.
Why do People Narrow or Widen Their VW Front Axles?
A. Often times axle beams are narrowed in lowered dune buggies and VW beetles to give more tire clearance at a lower ride height. Determining whether or not this is necessary depends on how low you want to go and your wheel and tire combination.
When front axle is narrow the torsion springs must be cut or replaced with shorter springs. Narrowing your stock torsion springs will stiffen them, as it shortens the distance of the material that twists to provide spring tension in your front end. Many narrowed beams are installed without shock towers due to this extra stiffness and a lack of room in the wheel well for shocks. We recommend keeping front shocks if possible to dampen front end oscillations, but it all depends from application to application.
In off road applications people like to widen their front beams for more stability. A wider front beam also helps gain more steering angle with larger wheels and tires. A wider stance can also be achieved with wider front trailing arms.
Since torsion springs cannot be lengthened a pair of smaller spring packs are typically installed in each side. Six inch wider torsion leave kits are available in the aftermarket. Some people also use two sets of stock torsion leaves in the beam.
Typically when a front axle is widened custom sized shock towers are installed. This gives users the ability to choose a shock more suited to the wheel travel they would like to have on their dune buggy front axle.
What is the Difference Between a Dual Port and Single Port VW Type 1 Engine?
A. VW Type 1 engines were made in two basic configurations through their lifespan. The early style of engine was called a single port and featured a single intake port on each cylinder head. The engines were produced in a variety of sizes and were installed in VW beetles until 1970.
The dual port engine was introduced in beetles for the 1971 model year. It featured twin intake ports on the cylinder head. This engine was produced in a few variations through the rest of the air-cooled VW beetle's lifespan.
A quick way to identify which engine you have is to follow the intake manifold from the carburetor to the cylinder head. If there is one tube connecting the intake to the cylinder head it is a single port engine. If the end casting on the cylinder head has a pair of humps that connect to the intake it is a dual port engine.
What is the difference between VW Type 1, Type 3 and Type 4 Engines?
A. The VW Type 1 engine is the most common air-cooled VW engine. It features an upright fan shroud and was found in all VW Type 1 beetles.
The Type 3 engine is a variant on the Type 1 that has rear mounted fan shroud giving it a "pancake" look. These engines had much in common with the Type 1, but all the engine tins are unique to the Type 3. Type 3 engines come stock in VW Fast Backs, Square Backs and Notch Backs.
VW Type 4 engines were found in late VW Buses, Porsche 914s and VW 411s. The Type 4 is a completely different engine platform than the type 1. It shares many of the same characteristics of the Type 1, but all the main components are unique to the Type 4. Like the Type 3, it features a rear mounted fan shroud with a pancake design.
Many small hardware components are shared between all three engines. Be sure to specify your application when searching for parts just in case you run into something specific to your variant of air-cooled VW engine.
What Type of Solex Style Carburetor Do I Need for My VW Bug or Dune Buggy?
A. There are different styles of stock carburetors out there. New stock replacement Solex style carburetors are designed to fit either single port engines or dual port engines.
The 30 Pict and 30/31 Pict carburetors are designed for single port engines.
The 30/31 Pict can also be used with dual port engines, as they are typically sold with an adapter that allows them to fit on a dual port manifold.
The 34 Pict carburetor is designed for VW dual port engines.
What Other Types of Carburetors are Available in the Aftermarket for the VW Type 1 Engine?
A. There are several common aftermarket performance carburetor options available.
VW Performance Single Carburetors
The first common upgrade is a Weber Progressive style carburetor. This is a two barrel carburetor that runs on one barrel when cruising and kicks in its secondary barrel at full throttle for a more powerful acceleration.
The next common carburetor is a single IDF Style carburetor that is center mounted on the engine. These are typically the same IDF style carburetors used in dual carburetor applications with different jetting and parts installed to run the entire engine. They can be had in 40 and 44 sizes. A dual carburetor set up as a single carburetor will require extensive changes to work properly as a single carburetor.
A newer single carburetor that is now available is the 38 E-Gas from EMPI. This is a two barrel carburetor similar to a progressive style carb. The difference is that this carbs barrels open together for a smoother acceleration with less hesitation.
VW Performance Dual Carburetors
The most economical dual carburetor setup available are dual ICT carburetors from EMPI or Weber. These are a pair of single barrel carburetors. They offer mild performance gains for small to medium sized engines.
The next option would be a set of Porsche Style Kadron dual carburetors. These are also a pair of dual single barrel carburetors. They tend to be a more expensive option compared to other carburetors, but have a replaceable throttle body at the base. They also offer nice performance gains and are very tunable.
IDF style carburetors are an extremely popular choice among VW engine builders. This carburetors feature individual barrels for each cylinder. They come in both 40 and 44 mm sizes from EMPI and Weber. These are the performance choice for many off road, street performance and racing enthusiasts. Parts are plentiful and the carburetors are very tunable.
Dellorto DRLA carburetors are very similar to IDF carburetors. They are offered in a wider variety of sizes than IDFs. Parts are a little more difficult to find for Dellortos.
IDA style carburetors are often the racer's choice. These carburetors are offered in larger sizes for big displacement engines. They are often used when maximum airflow is desired for your engine in race conditions.
Weber DCNFs are another option for dual individual barrel carburetors. These were apparently the carburetor of choice for VW Guru Gene Berg. These carburetors are popular with some road racing enthusiasts as they were initially designed for corner carving race cars.
There are many opinions and facets to carburetor choices. Our recommendation is to determine how you would like your vehicle to perform with considerations to your budget. Then look at how others have achieved this to determine what the best choice is for you.
We aren't married to any carburetor in particular, but we have always had good luck with IDF style carburetors. That is not to say that an engine can't be properly tuned with any of the other options. Some are more difficult to tune than others.
What Fuel Pressure Should I Run with My Engine?
A. For carbureted VWs fuel pressure should be between 1 PSI and 4 PSI. Typically stock engines need no more than 2 PSI of fuel pressure.
What are the Different Types of VW Beetle Mechanical Fuel Pumps?
A. VThere are two basic styles of mechanical fuel pumps. There is an early generator style fuel pump and a late style alternator pump.
The key thing to remember is that you must match the fuel pump pushrod to the fuel pump. Early style generator fuel pumps use a 108 mm Fuel Pump Pushrod. Late style alternator fuel pumps use a 100 mm fuel pump pushrod.
A quick way to determine what pump you have when inspecting a unit on your car is to look at the lever arm in the base of the fuel pump. You will have to remove the fuel pump from the engine to do this.
If the lever arm on your fuel pump sits below the flange on the pump it is a generator pump. If the lever arm sits just proud of the base of the pump you have an alternator pump.
What are the Different Styles of VW Spark Plugs?
A. There are three common styles of spark plugs used in air-cooled VW engines. The most common is the #7902 W8AC 14MM 1/2" reach spark plug found in many VW Type 1 engines. Performance VW Type 1 cylinder heads often use #7700 12MM 3/4" reach spark plugs. Many VW Type 4 engines use #7904 14MM 3/4" reach spark plugs.
What is the Standard Spark Plug Gap for Air-Cooled VWs?
A. Standard spark plug gap for a VW Type 1 engine with points is .024". This can vary slightly depending on ignition systems. Typically we recommend opening your gap with standard electronic ignition systems to about .030". Performance applications can vary on this depending on application.
What is the Difference Between a 009 Style Distributor and a Vacuum Advance Distributor?
A. There are several distributor options available for air-cooled VWs. Many VWs came from the factory with vacuum advance distributors that advance the timing as vacuum increases with engine revolution. Some factory VW distributors will both advance and retard timing with vacuum signals.
Vacuum advance offers smooth acceleration. It is ideal for factory style and mild performance engines.
Engines with larger camshafts can cause a decrease in vacuum signal that can cause issues with vacuum advance distributors.
VW 009 distributors mechanically advance timing with engine RPM. They use internal weights and centripetal force to advance timing. These are common with dual carburetor setups. They also can be used in stock applications.
Opinions vary on 009 distributors. They are extremely popular with many performance enthusiasts. Stock VW people seem to have mixed opinions. We recommend researching your application to determine what distributor is best for you.
What Things Should I Consider When Changing My VW Bug from Points to Electric Ignition?
There are several quick checks we recommend before installing an electronic ignition in your VW bug, bus or dune buggy.
The first thing you need to consider is which distributor you have. Electronic ignitions are made for both vacuum advance distributors and 009 style mechanical advance distributors. Make sure you choose the unit that fits your application.
Next determine which coil you have. Electronic ignition units typically require at least 3.0 Ohms of primary resistance to work. If you have less resistance in your coil it will fry the electronic ignition. Common compatible coils are Bosch Blue Coils, Beru Blue Coils and Pertronix 3.0 Ohm coils. Common coils that can cause issues are Accel 1.5 Ohm coils and MSD Blaster 1.5 Ohm coils.
Another thing to examine in your application is if you have good connections and no shorts at your coil. If the coil terminals are grounding to the body of the coil it can cause electronic ignitions not to fire properly. It may not burn the ignition up, but rather just cause a weak spark. If you have had issues with a few units take a good look at your connections.
Make sure the only wires on the negative side of your coil are a tachometer signal and the electronic ignition's negative lead. The positive lead on the ignition system goes to the positive side of the coil.