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Shimano SG-8C20, Service Manual

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Shimano SG-8C20 Service Manual Download Page 4

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4

The new standard in internal geared hubs

The NEXUS 8-speed system delivers a new level of design, quality and function. Our designers have updat-
ed the conventional internal hub with a refreshing new design inspired by the concepts of beauty, innova-
tion and integrity. Many technical advances have been achieved, like incorporating Shimano’s unique gear
change support mechanism that makes a real low effort shifting.

BR-IM70-R

Roller Brake

SG-8R25

Premium version

SG-8R20

Roller Brake

SG-8C20

Coaster Brake

SG-8R25-VS
SG-8R20-VS

V-Brake

Small Parts Set

FC-NX60

33/38T

FC-NX80

HOLLOWTECH 

Crankset

BL-IM65

3-finger 

Brake lever

BL-IM60

4-finger 

Brake lever

ST-8S20

3-finger

Brake lever

SL-8S20

SB-8S20

4-finger

Brake lever

BB-UN25

SG-8C20

SG-8R25

SB-8S20

ST-8S20

BL-IM65

SL-8S20

BL-IM65

Lay_INTER-8_GB 05 23.12.qxd  23.12.2004  13:39 Uhr  Seite 4

Summary of Contents for SG-8C20

Page 1: ...S SG G 8 8C C2 20 0 vol 1 SERVICE MANUAL GB SHIMANO NEXUS INTER 8 COASTER HUB Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 39 Uhr Seite 1 ...

Page 2: ...Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 39 Uhr Seite 2 ...

Page 3: ...the internal unit 14 Disassembly of the internal unit 16 Assembly of the INTER 8 coaster hub 21 Cassette Joint Measurement tool 28 NEXUS non turn washers 30 Hub dimensions O L D and axle 31 Spare parts list SG 8C20 32 Spare parts list SL 8S20 33 Spare parts list CJ 8S40 34 Spare parts list BL IM65 35 Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 39 Uhr Seite 3 ...

Page 4: ...ncorporating Shimano s unique gear change support mechanism that makes a real low effort shifting BR IM70 R Roller Brake SG 8R25 Premium version SG 8R20 Roller Brake SG 8C20 Coaster Brake SG 8R25 VS SG 8R20 VS V Brake Small Parts Set FC NX60 33 38T FC NX80 HOLLOWTECH Crankset BL IM65 3 finger Brake lever BL IM60 4 finger Brake lever ST 8S20 3 finger Brake lever SL 8S20 SB 8S20 4 finger Brake lever...

Page 5: ...izes shockless smoother shifting for stressless comfortable gear change Smoother Rotation Shimano s precise manufacturing abilities construct an internal hub that rotates with significantly less drag than previous models Close Ratio Wider Range The INTER 8 hub has increased its gear ratio to 307 compared to 244 of the INTER 7 hub ST 8S20 Shifter with 3 finger Brake Lever BL IM65 3 finger Brake Lev...

Page 6: ...opes as this will cause the internal brake parts to become very hot and this may weaken braking performance It may also cause a reduction in the amount of brake grease inside the brake and this can lead to problems such as abnormally sudden braking Spin the wheel and confirm that the braking force of the coaster brake is correct If the brakes are used frequently the brake drum may become hot Do no...

Page 7: ...t parallel to the chainstay 4 Fix the brake arm securely to the chain stay with the brake arm clip 5 Before using the Coaster Brake check that the brake works properly and that the wheel turns smoothly Clip nut Brake arm Brake arm clip Clip screw Tightening torque 2 3 N m 17 26 in lbs Different types of left and right non turn washers are available for use with standard and reversed fork ends Use ...

Page 8: ...sette joint pulley and then turn the pulley to loosen the inner cable Then remove the inner cable fixing bolt unit from the pulley first and after this remove the outer casing from the outer casing holder Remove the inner cable fix ing bolt unit 2 1 3 Pulley hole 2 mm Allen key or 14 spoke Slit Bracket Outer casing holder 1 2 Pull out from outer casing holder Remove from the slit Use a shifting ca...

Page 9: ... 6 N m 40 60 kgf cm Flats part of inner cable fixing washer Gap in pulley 10 Secure the cable to the frame with the outer casing bands 8 Turn the cable 60º counterclockwise and attach it to the hook 9 Attach the inner cable to the pulley as shown in the illustration pass the inner cable through the slit in the cassette joint bracket and then insert the end of the outer casing securely into the out...

Page 10: ... the shifting lever to 1 Connect the shifting cable to the shifting lever 2 Set the shifting lever to 3 Install the rubber cover and rubber bellows to the outer casing holder 4 Wipe away any grease which may be on the inner cable and then pass the inner cable through the rubber bellows After this insert the outer casing into the rubber cover and set it into the outer casing holder 1 While holding ...

Page 11: ... Attach the inner cable to the pulley as shown in the illustration pass the part of the inner cable which has the rubber bellows attached through the slit in the cassette joint bracket and then insert the outer casing holder securely into the outer casing holder section Be careful not to damage the rubber bellows at this time 1 Set the shifting lever to Check to be sure that the yellow setting lin...

Page 12: ...unit and carrier unit Trouble condition Remedy 04 PE LD 1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 SHIMANO NEXUS INTER 8 Coaster Hub SG 8C20 Internal Assembly CJ 8S20 Internal Hub Grease For coaster brake also TL 8S30 TL 8S20 TL 8S11 Abnormal noise still occurs after adjusting cable Replace the hub axle unit and carrier un...

Page 13: ...ub doesn t work Replace the carrier unit and hub axle unit While not pedaling Gear Unsmooth Replace the hub axle unit and carrier unit Replace the carrier unit Replace the hub axle unit and carrier unit 4 8 Except 4 8 4 8 Except 4 8 Replace the right hand cone and driver Replace the brake shoe unit Driver unit axle unit Braking force is weak Replace the brake shoe unit Pedal turning angle for brak...

Page 14: ...ols Note For internal unit replacement only tools e and f are necessary a Hammer b TL 8S11 Right Hand Cone Removal Tool Part No Y 708 00600 a b c e f d 1 Hold the two bevelled surfaces of the hub axle on the brake arm side in a vice and remove the dust cap 2 Turn the hub upside down and hold the two bevelled surfaces of the hub axle on the sprocket side in a vice Note Do not damage the threads of ...

Page 15: ... ball retainer B from the hub axle 4 Remove the hub shell Hub shell Internal assembly Now it can be replaced with the new internal assembly Disassembly and assembly can be carried out quickly Part No 36P 98010 Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 39 Uhr Seite 15 ...

Page 16: ...emove the ring gear slide spring with a screwdriver 3 Remove carrier unit and ring gear by lifting straight up Do not rotate to disengage Screwdriver Stop ring Y 33Y 19000 Ring gear 1 Y 35P 11000 Ring gear slide spring Y 35P 12000 Carrier unit Y 35P 98040 Brake shoe unit 1 Remove the brake shoe unit Disassembly of the internal unit Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 39 Uhr Seite 16 ...

Page 17: ... locknut with a 17mm hub spanner 6 Reverse axle unit in vice to access the drive side cone assembly Stop washer Y 34R 09000 Right hand locknut Y 33Z 07020 8 Remove the stop washer Ball retainer O Y 34R 98030 Pawls B Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 39 Uhr Seite 17 ...

Page 18: ...o the groove such that the pawl A is contacting the notch in the tool see detail Strike the tool with the hammer until cone and axle unit are separated A A 9 Remove the lock washer 10 Remove the driver plate Lock washer Y 34R 98090 Driver plate Y 34R 12000 Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 39 Uhr Seite 18 ...

Page 19: ...4R 98080 Return spring A Y 34R 21000 13 Remove the ball retainer P 3 16 X13 12 Reverse the right hand cone 14 Remove the driver unit 15 Remove the return spring A Ball retainer P Y 34R 98070 Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 39 Uhr Seite 19 ...

Page 20: ...it by turning it counterclockwise and aligning the two teeth to the two grooves as shown This completes the disassembly of the INTER 8 coaster hub Clutch unit Y 35P 98060 Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 39 Uhr Seite 20 ...

Page 21: ...ith the largest coil downward The spring should sit in the groove on the clutch unit shown as a blue line in the picture Be careful not to install the return spring A upside down Set drive unit while turn it counterclock wise Clutch unit Y 34R 98050 Clutch unit Y 35P 98060 Return spring A Y 34R 21000 NOTE Assemble the driver unit while pushing pawls B as shown in the picture 1 With the hub axle un...

Page 22: ...tion as shown in the picture 5 When installing the right hand cone align the two serrations with the grooves in the axle as shown Set the cone instal lation tool TL 8S20 and strike it until it comes to a stop Driver plate Y 34R 12000 Ball retainer P Y 34R 98070 Y 041020800 Right hand cone Y 34R 98080 Tool TL 8S20 Y 708 00200 seal seal ok ok Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 40 Uhr Seite 22...

Page 23: ...he right hand locknut with a 17mm hub spanner 10 Reverse the axle unit in the vice to complete assembly 8 When installing the stop washer align the two teeth with the two grooves of the lock washer Right hand locknut Y 33Z 07020 Y 041020800 Lock washer Y 34R 98090 Stop washer Y 34R 09000 Tightening torque 25 30 N m 218 261 in lbs Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 40 Uhr Seite 23 ...

Page 24: ... three planetary gears and install the ring gear Ring gear 1 stop ring Y 34R 80000 Tool TL 8S30 Y 708 00300 Y 041 20800 Y 041 20800 Y 041 20800 Carrier unit Y 35P 98040 Ring gear 1 Y 35P 11000 Ball retainer O Y 34R 98030 Pawls B Without any tools Align the three marks which are on the planetary gears as shown in the picture 11 Install the ball retainer O 3 16 X 26 while pushing pawls B one by one ...

Page 25: ...and carrier unit with the groove in the hub axle unit Install ring gear and carrier unit slowly Important To set all four pawls in the correct position Use a flat blade screwdriver to depress pawls as shown during assembly Turn unit and check that all pawls are in the proper position Pawls Y 041 20600 A B A B Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 40 Uhr Seite 25 ...

Page 26: ... stop ring it is likely that the ring gear and carrier unit are not properly assembled return to assembly step 13 16 Install the hub shell unit while turning it counter clockwise 17 Place ball retainer B onto the hub shell Note Be careful of the setting direction Apply a liberal coating of internal hub grease Brake shoe unit Y 35P 98020 Y 041020800 Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 40 Uhr ...

Page 27: ...inside and out side of the brake shoe unit 20 Install the dust cap This completes the assembly of the INTER 8 coaster hub 19 Screw the stop nut to adjust so that the hub shell can be turned smoothly without any play After adjusting secure the stop nut with the locknut Brake arm unit Y 35P 98080 Brake shoe unit Y 35 98020 Serrations TL 7S20 Locknut 17mm Y 35P 28000 Stop nut 22mm Y 35P 22000 Back si...

Page 28: ...J 8S20 for 8 speed CJ 8S40 for 8 speed TL CJ10 for CJ 8S20 TL CJ40 for CJ 8S20 TL CJ40 for CJ 8S40 Cassette Joint Measurement Tool 127mm 101mm 101mm Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 41 Uhr Seite 28 ...

Page 29: ...nal spec BELT DRIVE Hub Shell Internal Unit Internal Unit SG 8R20 SG 8R45 SG 8R25 YES NO YES NO NO NO YES NO NO YES NO YES NO YES 1 Possible not recommended SG 8R20 standard Mass production replacement SG 8R45 for CYBER NEXUS SG 8R25 Premium Mass production 8R20 type Ring gear 2 Mass production Replacement 8R20 type Ring gear 2 CHAIN DRIVE Hub Shell Internal Unit Internal Unit SG 8C20 SG 8C45 YES ...

Page 30: ...ood Reversed fork end For right hand side For left hand side Standard fork end 5R L 7R L 6R L NEXUS non turn washer application chart NEXUS non turn washers 5R Yellow 6R Silver 5L Brown 6L White 5R L 7R L 6R L 7R 7L 7R 7R 5R 5R 6R 5R 7R 6R 6 R 7R Black 7L Gray 3 8 º 2 0 º 9 9 º 1 1 0 º 2 6 1 º 2 5 0 º 7 7 º 2 8 3 º Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 41 Uhr Seite 30 ...

Page 31: ...3 1 2 X1 8 or 1 2 X3 32 CN NX10 42 85 47 85 2 55 SB 8S20 ST 8S20 SL 8S20 CJ 8S20 CJ 8S40 31 Hub dimensions Over Locknut Dimension and Axle Gear Ratio Function Name INTER 8 coaster SPEC FOR REVERSED FORK END AND FULL CHAIN CASE FOR REVERSED FORK END FOR STANDARD FORK END MARKING 5L 6L 7L COLOR BROWN WHITE GRAY SPEC FOR REVERSED FORK END AND FULL CHAIN CASE FOR REVERSED FORK END FOR STANDARD FORK EN...

Page 32: ...r P 3 16 x 13 Right Hand Cone w Seal Driver Plate Lock Washer Stop Washer Right Hand Lock Nut 3 4 mm Cap Nut 3 8 Non turn Washer 5L Brown Non turn Washer 6L White Non turn Washer 7L Gray Left Hand Lock Nut 3 mm Stop Nut Brake Arm Unit Ball Retainer B 3 16 x 16 Hub Shell Slide Spring Right Hand Dust Cap A w Seal Sprocket Wheel 16T Silver Sprocket Wheel 18T Silver Sprocket Wheel 19T Silver Sprocket ...

Page 33: ... SL 8S20 1 2 3 4 1 2 3 4 DESCRIPTION ITEM NO SHIMANO CODE NO Y 6FD Y 6F0 Y 61W Y 6F4 98010 04000 98030 09000 Bracket Cover Fixing Screw Cover Fixing Screw Cable Adjusting Bolt Unit Clamp Screw M4 x 23 5 Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 41 Uhr Seite 33 ...

Page 34: ...E NO Y 74Y Y 74Y Y 74Y Y 74Y Y 74Y Y 33Z Y 74Y Y 74Y Y 74Y 98160 27000 28000 30200 98140 98020 98150 18000 98030 Outer Casing Holder Unit Rubber Cover Outer Casing Holder Rubber Bellows Cassette Joint Unit Cassette Joint Fixing Ring Cassette Joint Driver Cap Inner Cable Fixing Bolt Unit Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 41 Uhr Seite 34 ...

Page 35: ...M NO SHIMANO CODE NO Y 8TS Y 6JB Y 89E Y 8SB Y 89M 98020 98040 05010 10000 08010 L H Adjustment Block Screw Cable Adjusting Bolt M10 x 19 Nut Reach Adjusting Screw M4 x 10 8 Clamp Bolt M6 x 14 8 Grip ø22 2 mm Black For Left Hand 3 Finger Lay_INTER 8_GB 05 23 12 qxd 23 12 2004 13 41 Uhr Seite 35 ...

Page 36: ...10 Fax 47 66778011 HALLMAN SPORTS OY Finland Phone 358 20 1550 800 Fax 358 20 1550 801 MACARIO LLORENTE S A Spain Phone 34 91 329 5070 Fax 34 91 329 2594 91 329 2039 MADISON CYCLES PLC UK and Ireland Phone 44 208 385 3385 Fax 44 208 385 3443 M I C MILAN INTERNATIONAL COMMERCE SpA Italy Malta and Tunesia Phone 39 331 467 311 Fax 39 331 464 790 NIKOS MANIATOPOULOS S A Greece and Cyprus Phone 30 2610...

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