BMW R32 vs. BMW R37: Any Special Update of BMW?

The world of classic motorcycles appeals to select individuals with a peculiar taste. For these people, the reason for going vintage differs. It could be the feel of the air rushing against their faces, the freedom that comes with riding on two wheels, ease of maintenance (no new or fancy electronics), manual controls, its massive size, and antique design, or the satisfying throttle sound. Whatever it may be, classic motorcycles have come a long way.

A common question most people ask is, when is a motorcycle considered “classic”? The answer to this question depends on who you ask. However, anything that’s at least 20 years old and above is well within the vintage group.

In this article, we will talk about two classic motorcycles, the BMW R32 and BMW R37. We will bring them toe-to-toe with each other, highlighting and comparing their key features. But, before we do that, here is what you have to know about the BMW R32 and BMW R37.

BMW R32

The BMW R32 is the first motorcycle developed by BMW in December 1922. The bike featured BMW’s infamous box engine. Its smooth design and solid framework were nothing like the motorcycles of its time. This was an impressive achievement from a company that was known mostly for its manufacturing of large engines. The design concept of the bike was perfectly matched with superior material quality and eye-catching aesthetics. The low engine provided more stability and instead of the popular belt or chain, it featured a Cardan-shaft drive with its gearbox connected directly to the engine. This gives it a smoother ride and a higher efficiency since less energy was lost in transmission. It was a resounding success and one that lunched BMW into the top position among motorcycle manufacturers. It also heralds the way for other classics like the BMW R37.

BMW R37

The BMW R37 is a racing model classic motorcycle. It was unveiled in 1925, few years after the R32 took the world by storm. The R37 was the first motorcycle from BMW to have the overhead-valve gear design. Its technology was similar to that used by the company in the design of its aircraft engines at the time. Developed strictly as a racing bike, the BMW R37 gave an impressive performance with an engine that delivered up to 20 HP on Tap. This is almost 5 times more than that of its predecessor, the BMW R32. With only about 150 of these ever built, the R37 is one of the rarest classic motorcycles.

Overview Specification Table

BMW R32BMW R37

Production Year

1923
1925
Manufacturer
BMW AG

BMW AG

Power

8.5 hp @ 3200 rpm

16 hp @ 4000 rpm

Max Speed

95 km/h (59 mph)

115 km/h (71.5 mph)

Transmission

3-speed manual

3-speed manual

Wheelbase

1,380 mm

1,380 mm

Rear Brake

Block
Block

Cooling System

Air-cooled

Air-cooled

Bore/Stroke

68 mm x 68 mm

68 mm x 68 mm

Front Tyre

26 x 3

26 x 3

Rear Tyre

26 x 3

26 x 3

Fuel Capacity

14 liters

14 liters

Design Comparison

In terms of design, the BMW R32 and BMW R37 shared certain similarities and also had key differences. For instance, the boxer engine configuration was maintained in both models. However, there are several key differences in the design of both classic motorcycles. With the BMW R37, the company was aiming for better speed. To achieve this, several nifty changes were made to the original M2B33 engine that was used in the BMW R32. A few changes were also made to the original chassis although some features like the wheel size, transmission type, and bore/stroke diameter remained the same in both models.  Although the R37 has a wet weight that is higher than its predecessor the R32, the engine is far superior. The 4-stroke twin-cylinder engine of the BMW R37 delivers twice as much horsepower and a higher RPM.

Main differences between the BMW R32 and the R37

Engine

The major difference between the R32 and R37 BMW classic motorcycles is the engine. The original engine of the R32 was replaced with an upgraded version on the R37. While the BMW R32 engine has a cast-iron cylinder and head unit, the R37 has a light aluminum alloy cylinder with fully enclosed valves. The R32 also has a side valve and the cylinder head projects outward on both sides for cooling. This design is prone to clogging by dust and water, and would often require manual lubrication. On the other hand, the BMW R37 has overhead valves that are fully enclosed. This eliminates the problem of clogging and makes it easier to maintain.

With a higher speed and fully enclosed design, the cooling system had to be devised for the R37. Although both models are air-cooled, enclosing the valves and cylinder meant that air had to be channeled to the cylinders to prevent over-heating. BMW patented a circumferential cooling fin that allows cooling tubes to be passed around the valves within the engine.  

The BMW R32 engine was capable of delivering a top speed of 95 km/h and 8.5 horsepower at 3200 rpm. These specs weren’t bad at the time. The R32 was still a major contender. Howbeit, it lacks the finesse of its faster sibling, the R37 which can run up to 115 km/h. The faster R37 engine delivers a power of 16 HP at 4000 rpm.

Weight

Another difference between the BMW R32 and R37 is the weight. The R32 has a wet weight of 122 kg (269 lbs.) while the R37 weighs 134 kg (295.4 lbs.) (wet). This is the overall weight of the bike inclusive of the weight of fuel, engine oil, coolant and brake fluid, etc

Braking System

Both the R32 and R37 have the drum (in front) and block (at the rear) braking system. But, earlier models of the R32 did not have a front braking system. Instead, braking was done using a set of two padded brake shoes attached to the brake drum on the rear wheel. These two brake pads were operated by two levers both on the right side of the motorcycle. One of the brake pads was operated with a hand lever and the second was operated with a lever positioned near the heel. This design was changed with later iterations of the R32 models. The right-hand lever and brake were moved to the front wheel.

Fuel Capacity and Consumption

Both R32 and R37 BMW classic motorcycle models come with a 14 liters (3.70 gallons) fuel capacity. However, the consumption rate differs with each model. The BMW R32 has a fuel consumption rate of 3 liters per 100 kilometers, while the R37 model has a consumption rate of 4 liters for the same distance.

Compression ratio

The engine compression ratio of the BMW R32 differs from that of the BMW R37. The R37 has a higher compression ratio of 6.5:1 while the R32 engine has a compression ratio of 5:1. The higher compression ratio of the R37 means it is capable of producing more power compared to the R32. It also means the BMW R37 will run on gasoline that has a higher octane rating. These changes were made to the original engine to increase the performance and speed of the BMW R37.

Similarities between the BMW R32 and BMW R37 models

These two classic motorcycles are similar in many ways. With just over a year between them, the company maintained several design features. Some of these include;

Chassis

The BMW R32 and R37 both have a similar external design. Each has a tubular steel frame with a 14-liter tank. The front and rear tires on both motorcycles are of sizes 26” x 3” for both. The front wheel of both motorcycles uses a twin cantilever spring suspension type, while the back wheel is rigid. The braking system consists of a drum brake for the front wheel and a block brake for the back wheel. The drum brake has a diameter of 150 mm on both motorcycles.

Drive

Both the R32 and R37 have a 3-speed manual transmission with a shaft drive (Cardan) transmission type. They also use a dry-cable single plate clutch system.

Bore and stroke

Another similarity is the size of the bore and stroke. The original dimension of 68mm x 68mm is used in both the R32 and R37 classics.

Lubrication Type

Both the BMW R32 and R37 use a circulating wet sump oiling system. The BMW R32 is the first motorcycle to use this lubrication system as of when it was manufactured. Prior to that, most other engines were using the total-loss oiling system. The wet sump system allowed the motorcycle to conserve oil by recirculating it within the engine. It also allows the engine to have a more compact design since it doesn’t require an external oil canister. This design was also used in the BMW 37.

Ignition System

The Bosch magneto ignition system is used in both the BMW R32 and BMW R37. 

Engine Size

Despite having glaring differences in speed and performance, both the R32 and R37 use similar engine blocks. This is the 494 cc four-stroke engine with two cylinders. It also uses the “boxer configuration”.

Price

The auction price of any of these classics is likely going to be much higher than when it was first released. But before talking about that, here’s how much these classics cost in their days. According to the BMW Group website, the BMW R32 retailed for 2,200 marks. This will worth $1,300 today. As of then, this was very expensive and a daring move by BMW, considering it was new to the game. However, the R32’s design with “latest specs” made it worthwhile. The BMW R37, an upgrade from the R32 was sold for 2900 marks which are about $1700 today.

Being classic motorcycles, they are no longer sold based on their original prices. Now, BMW R37 is estimated to cost between $150,000 – $175,000. For the BMW R32, the latest known auction price in 2019 is $220,000.

Conclusion

Conclusion

The BMW R32 is a legacy motorcycle that was launched with many new features, most of which were not available at the time. It was also officially the first motorcycle to be tagged a “BMW”. This came after several failed attempts by the company. The Flink and Helios, both of which preceded the BMW R32 were a complete disaster. BMW’s incredible designer director Max Friz who was instrumental in the design of the R32 chose a completely different design language.

The result was the BMW R32. Its exemplary design concept was audacious and challenged the “status quo” of the time. This forced many manufacturers to return to the design table and come up with new concepts. The Boxer engine used in the R32 is still in use today and it’s one of the things that the BMW motorcycles are well-known for. 

The BMW R37 carried on the legacy of the R32 model. Nicknamed “Supermodel”, this motorcycle was one of the fastest in its time and the fastest motorcycle that the company had produced. The R37 was in no way inferior to its sibling the BMW R32. It featured top-notch specs and an improved engine design.

The R37 was extremely successful and won several competitions. The first victory was in 1924 when Franz Bieber won the Eiffel Bergrennen race riding on the R37. This was just the beginning of several victories to come. In the same year, 3 riders won in 3 different categories in a hill-climbing challenge. Rudi Reich who was one of the riders using the latest BMW R37 held the record for the fastest time for the day, beating several other riders. 

With so much legacy and history, it comes as no surprise that the BMW R32 and R37 are among the rarest and most sort after classic motorcycles. 

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