Evaluation of DR650SE Sprocket Hub Bearing Strategies

As is now fairly well known, DR650SE sprocket hubs have a tendency to wear out bearings and bearing bores. There are a number of strategies which can be used to address the issue, which all have advantages and disadvantages. Those unnecessarily complex or unsuitable for other reasons are not included here.

Evaluation criteria:

1. Sprocket side bearing load offset – how far the sprocket centerline is away from the bearing rolling element’s centerline. This is important because the more offset, the more moment load the bearing is subjected to.
2. Damper side bearing load offset – how far the damper centerline is away from the bearing rolling element’s centerline. Again, this is important because the more offset, the more moment load the bearing is subjected to.
3. Bearing location symmetry – how close to centered between the loads the bearings are. This is important because it determines how balanced the loads will be.
4. Hub bearing engagement surface area – how much engagement the outer races of the bearings have in the hub. This is important because the more engagement there is, the less likely the hub’s bearing bores are to wear out during use.
5. Distance between ball row centers – how far the rolling elements are located from each other. This is important because the further the rolling elements are from each other, the less moment load the bearings have to contend with.
6. Number of seals – the total number of bearing seals, including both those that are part of the bearing, and those that are separate ( i.e. installed in the bearing bore). This is important because it determines how well lubrication is kept in, while dirt & water are kept out.
7. Weight of assembly. This is important because it is best to keep the unsprung mass as low as possible.

DATA

OEM Hub

Narrow Double-Row Bearing Retrofit

Double-Row Bearing Retrofit

Aftermarket Stacked Bearing Hub

Inner Bearing Retrofit, OEM Hub

Inner Bearing Retrofit, Aftermarket Hub

Sprocket side bearing load offset in mm

10.16

4.16

2.21

6

10.16

10.16

Damper side bearing load offset in mm

32.04

29.04

29.69

36.2

14.94

14.94

Bearing location symmetry in percent

31.7

14.3

7.4

14.2

68

68

Hub bearing engagement surface area in sq cm

21.24

26.14

30.39

31.89

35.49

35.49

Distance between ball row centers in mm

0

9

10.3

12

17.1

17.1

Number of seals

2

3

2

4

6

6

Weight of assembly (with outer spacer) in grams

~1000.63

~1050.62

~1052.22

~1038.87

-1048.37

~1026.87

SCORING

OEM Hub

Narrow Double-Row Bearing Retrofit

Double-Row Bearing Retrofit

Aftermarket Stacked Bearing Hub

Inner Bearing Retrofit, OEM Hub

Inner Bearing Retrofit, Aftermarket Hub

Sprocket side bearing load offset

1

4

5

3.1

1

1

Damper side bearing load offset

1.8

2.3

2.2

1

5

5

Bearing location symmetry

2.5

1.4

1

1.4

5

5

Hub bearing engagement surface area

1

2.4

3.6

4

5

5

Distance between ball row centers

1

3.1

3.4

3.8

5

5

Number of seals

1

2

1

3

5

5

Weight of assembly (with outer spacer)

5

1.1

1

2.1

1.3

3

Overall score (i.e. average of individual scores)

1.9

2.3

2.5

2.6

3.9

4.1

Another factor is that the aftermarket stacked bearing hub comes with Chinese-made bearings, but it did not seem reaonable to include this in the data nor the scoring because they're not inherent to the design (i.e. they can easily be replaced with something else).

Stock Sprocket Hub Cross-Section

Cross-section of stock DR650SE sprocket hub.

Narrow Double-Row Bearing Sprocket Hub Cross-Section

Cross-section of stock DR650SE sprocket hub with narrow double-row bearing, narrower outer seal, and correspondingly modified outer spacer.

Double-Row Bearing Sprocket Hub Cross-Section

Cross-section of stock DR650SE sprocket hub with wide double-row bearing and correspondingly modified outer spacer.

 Stacked Bearing Sprocket Hub Cross-Section

Cross-section of aftermarket stacked bearing DR650SE sprocket hub.

Modified Stock Sprocket Hub Cross-Section

Cross-section of stock DR650SE sprocket hub with inner bearing retrofit.