When it comes to rotors, racers are constantly searching for the ultimate balance between the lowest weight and the ability to effectively manage heat. Decreased rotating weight in the drive line provides quicker deceleration under braking and quicker acceleration out of the corners. Lower weight also benefits handling with improved spring and shock control over the unsprung suspension mass. Wilwood's
ULD - 32 drilled and ULS - 32 scalloped iron rotors provide two highly effective lightweight options for sprints, late models, modifieds, and other competition applications that race in low to medium temperature ranges.

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ULD - 32 Series Drilled Straight Vane Vented Rotors feature a two row, 64 hole pattern that alternates between and directly over each vane. Each hole is deeply chamfered to eliminate any stress points that could result in premature cracking at the drill holes. The drilling process removes an average of one pound from each rotor. Rotating and unsprung rotor mass is reduced by as much as 12%.

Caution on drilled rotors: There is a common mis-perception that rotors are drilled to improve cooling. The reduced mass of a drilled rotor will dissipate its retained heat quicker, but it also builds up heat at a much faster rate. The decision to use drilled rotors should be solely based on the merits of the lower rotating and unsprung weight, and not for improved cooling. It is not wise to use drilled rotors in sustained high heat on hard braking tracks unless the team budget affords a high frequency of rotor and brake pad replacement.

Diameter

Width

Bolt Circle

Hole Type

Far Side I.D.

Lug I.D.

Weight LBS

Rotor
Type

Part
Number

12.19" (309,6)

.81" (20,6)

8 x 7.00" (177,8)

.325"

8.50" (215,9)

6.38" (162,0)

8.0

ULD- 32

160-5865

11.75" (298,5)

1.25" (31,8)

8 x 7.00" (177,8)

.325"

8.34" (211,8)

6.38" (162,0)

7.7

ULD- 32

160-5864

11.75" (298,5)

.81" (20,6)

8 x 7.00" (177,8)

.325"

8.34" (211,8)

6.38" (162,0)

7.2

ULD- 32

160-5863