Discussion
How much ? Looking for set to get re-furbed, save having car sat on drive on blocks while being done then sell mine ?
Pitch circle diameter ( not radius ! )is distance, in milli-metres from centre of one stud to centre of diagonally opposite stud, easy enough to measure on four stud wheels, little more difficult on five studs.
Pitch circle diameter ( not radius ! )is distance, in milli-metres from centre of one stud to centre of diagonally opposite stud, easy enough to measure on four stud wheels, little more difficult on five studs.
Edited by phillpot on Thursday 4th June 20:31
phillpot said:
How much ? Looking for set to get re-furbed, save having car sat on drive on blocks while being done then sell mine ?
Pitch circle diameter ( not radius ! )is distance, in milli-metres from centre of one stud to centre of diagonally opposite stud, easy enough to measure on four stud wheels, little more difficult on five studs.
Yep I knew what I meant! Wrong words though!Pitch circle diameter ( not radius ! )is distance, in milli-metres from centre of one stud to centre of diagonally opposite stud, easy enough to measure on four stud wheels, little more difficult on five studs.
Nicked from Wikipedia
The bolt circle is the circle determined by the positions of the bolts; the center of every bolt lies on the circumference of the bolt circle.
The important measurement is the "pitch circle diameter" (PCD), usually expressed in millimeters, although inches are sometimes used. For a 4- or 6-bolt car, this measurement is merely the distance between the center of two diametrically opposite bolts. In the 4-bolt picture to the right, this would be the distance between holes #1 and #4. Some basic geometry is needed to find the center of a 5-bolt pattern: draw a line between any two neighboring bolts, and draw a line from the midpoint of this line to the opposite bolt. Repeat with a different set of three bolts, and the two long lines will cross in the center, thereby making the distance between this intersection and the center of a bolt the radius of the bolt circle.
The PCD can be calculated for any wheel from the number of bolts (n) and the measured center distance between two adjacent bolts (d) as; PCD = d / SIN(180/n).
A 1974 MG B is a 4/4.5" (4/114.3) car, meaning it is, again, a 4-bolt pattern with a 4.5" or 114.3 mm bolt circle.
The most common PCD values are 100 mm and 114.3 mm. This difference arises from the manufacturers' measurement convention - whether they are designing around metric values (100 mm) or imperial values (4.5 inches, i.e. 114.3 mm).
So there
The bolt circle is the circle determined by the positions of the bolts; the center of every bolt lies on the circumference of the bolt circle.
The important measurement is the "pitch circle diameter" (PCD), usually expressed in millimeters, although inches are sometimes used. For a 4- or 6-bolt car, this measurement is merely the distance between the center of two diametrically opposite bolts. In the 4-bolt picture to the right, this would be the distance between holes #1 and #4. Some basic geometry is needed to find the center of a 5-bolt pattern: draw a line between any two neighboring bolts, and draw a line from the midpoint of this line to the opposite bolt. Repeat with a different set of three bolts, and the two long lines will cross in the center, thereby making the distance between this intersection and the center of a bolt the radius of the bolt circle.
The PCD can be calculated for any wheel from the number of bolts (n) and the measured center distance between two adjacent bolts (d) as; PCD = d / SIN(180/n).
A 1974 MG B is a 4/4.5" (4/114.3) car, meaning it is, again, a 4-bolt pattern with a 4.5" or 114.3 mm bolt circle.
The most common PCD values are 100 mm and 114.3 mm. This difference arises from the manufacturers' measurement convention - whether they are designing around metric values (100 mm) or imperial values (4.5 inches, i.e. 114.3 mm).
So there
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