AP Racing Catalogue Issue 4

42 visit www.apracing.com for installation drawings & up to date product range details BRAKE DISCS - Bolted & Float in the Bell Mounting DISC MOUNTING Most racing and many high performance road brake discs are designed to be mounted on to the hub or stub axle by means of a mounting bell. Mounting bells are usually made from high grade Aluminium alloy although other materials can be used. This arrangement is much lighter than a one piece disc and bell, but more importantly allows some compliance to reduce the risk of distortion due to heat expansion of the disc. This becomes more important the larger the disc and is considered essential above Ø330mm diameter. There are essentially two methods of attaching the disc to the bell, ‘Bolted’ and ‘Floating’. The method to be used will depend on the particular application. BOLTS AND BOLT KITS E8 - 6 Lobe, ¼” UNF Headed Bolt kits available for AP Racing discs are given in the table below. The 6 Lobe bolt offers the following advantages over a cap head: - More positive drive. - More consistent clamping loads. - Lighter. - Improved corrosion resistance - Less prone to damage. - Improved airflow. BOLT DIMENSIONS. ◘ AP Racing recommend a bolt / nut tightening torque for a disc and bell of 14Nm (10.5lb/ft). Individual ¼” Bolts, Nuts and Washer Components in boxes of 100 Component. E8 - 6-Lobe Head Type Part Nos. Alternative Cap Head Type Part Nos. .875” Long Bolt CP3845-100K100 CP2494-116K100 1.00” Long Bolt CP3845-101K100 CP2494-718K100 1.062” Long Bolt CP3845-102K100 CP2494-331K100 Nut CP2494-117K100 Washer CP2494-1305K100 N.B. BOLTS, NUTS AND WASHERS NOT SOLD INDIVIDUALLY E8, 6-LOBE HEAD BOLT KITS (All Bolts ¼” UNF) Kit Part No. No. of Bolts in kit. Bolt Part No. CP3845-100K08 8 CP3845-100 - .875” long. CP3845-102K10 10 CP3845-102 - 1.062” long. CP3845-100K12 12 CP3845-100 - .875” long. CP3845-101K12 12 CP3845-101 - 1.0” long. CP3845-102K12 12 CP3845-102 - 1.062” long. Each of the above kits contain the required number of CP2494-117 Nuts & CP2494-1305 washers. Note: 3/8” E8, 6-Lobe Socket - CP2494-153 is available IDENTIFICATION LETTER TO BE CLEARLY MARKED WHERE SHOWN AS LARGE AS POSSIBLE 1 HOLE 6.45 6.40 THRU Ø18.00 R0.10 MAX ALL ROUND 8.25 8.20 2.50 11.96 11.92 5.00 10.00 Ø BOLTED For lower duty applications and on smaller discs a bolted mounting is sometimes preferred for strength and simplicity especially for off-road application (e.g. Rallies) where debris may clog a floating mechanism leading to run-out and disc vibration. Stiff flat bells should be avoided with a bolted mounting. Standard AP Racing disc mounting hole size is 6.40 / 6.45mm diameter. AP Racing offer a range of bolts, nuts and washers to suit. These are also available in wheel set kits, see below for details. ◘ NOTE: Bolts, nuts and washers are not available separately, but can be purchased in boxes of 100. The Cap Head bolt will continue to be available as a loose part in kits of 100. ‘L1' ‘L2' ◘ Bobbin kit CP4015-101K12 CP4015-101MA bobbin can be bought separately or in a kit which contains the bobbins, bolts, nuts & washers. ◘ CP4015 Float in the bell Bobbins. The bobbin for use with ‘float in the bell’ mounting is CP4015-101MA ¼”UNF Bolt Dimensions and Part Numbers. (Dim’n in mm) Bolt Part No. Dim’n ‘L1’ Dim’n ‘L2’ CP3845-100 22.2 9.5 CP3845-101 25.4 12.7 CP3845-102 27.0 14.3 CP3845-107 30.2 17.5 Note: For the most up to date installation drawing and mounting bell dimension details visit - https://apracing.com/race-car/brake-discs/floating-disc-mounting- cp2494-cp4135-cp7016-cp4015-types FLOATING Discs for heavy duty applications, especially larger discs, should be mounted to allow some axial & radial float between disc & bell. This may be achieved by the following methods currently available from AP Racing:- - Float in the bell. - Float in the disc. - ‘I’ Drive. - Strap Drive. Radial float allows differential expansion of disc and bell thus reducing stresses in the disc and minimising disc cracking and distortion. The idea of axial float is to compensate for a certain amount of stub axle / upright flex by allowing the disc to take up its ideal position within the range of float thus avoiding ‘Knockback’ of the caliper pistons. However the float should not be excessive as disc gyroscopic loads can cause the same effect that the float is meant to alleviate. The amount of axial float will depend somewhat on the application. In a ‘perfect’ system with minimal disc movement relative to the Caliper the amount of float need only be around 0.15 - 0.25mm. FLOAT IN THE BELL The AP Racing ‘Float in the Bell’ system has the advantage of being used with standard bolted discs, float is controlled by bell thickness. During use some wear of the bell inevitably occurs which tends to increase float and requires more frequent Bell replacement than the Float in the Disc system. NOTE:- Recommended bell flange thickness for use with this bobbin is 8.00 / 8.05 to give 0.15 / 0.25mm float. CP2494-117 0.25" UNF NUT. CP2494-1305 WASHER CP3845-100 6 LOBE 0.25" UNF BOLT BRAKE DISC MOUNTING BELL 8.25 8.20 BOBBIN LENGTH EFFECTIVE RECOMMENDED FLOAT 0.25 0.15 CP2494-117 NUT TIGHTENING TORQUE -14Nm (10.5lb/ft) CP4015-101MA BOBBIN CP3845-102 BOLT CP2494-1305 WASHER BRAKE DISC MOUNTING BELL NOTE: THE CORRECT ORIENTATION OF BOBBINS