Caster setting with 17's
10-03-2003, 09:35 PM
#1
Racer
Thread Starter
Caster setting with 17's
What's the proper caster setting when running 17" rims and tires?TIA
10-03-2003, 10:12 PM
#2
Caster should not change due to wheel size. You should try to maintain the same rolling diameter though.
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10-03-2003, 10:47 PM
#3
Race Director
If you maintain the same rolling-diameter with a 225/45-17 or 255/40-17 tire, it shouldn't make much of a difference. However, the extra width DOES increase the tendency to tramline on uneven surfaces and the car is more likely dart to one side under braking if you hit a bump with one tire only. To combat these behaviors, Porsche recommends increasing the caster setting:
------------------------------------------
ARTICLE BEGINNING
TECHNICAL SERVICE BULLETIN
17 INCH APPROVED WHEELS & TIRES
Model(s): 1987-On Porsche 944 (with M30 option)
1987-On Porsche 944S (with M30 option)
1987-On Porsche 944 T (with M30 option)
1988 Porsche 944 Turbo S
1989 Porsche 944 Turbo
1989-On Porsche 944 S2
Group: 4
Bulletin No.: 9303
Date: September 28, 1993
SERVICE INFORMATION
Concern
Installing 17" Porsche wheels on vehicles previously equipped with 16" wheels.
SERVICE PROCEDURE
Installation Information 1. Front and rear fender well lips must be reworked and/or checked for adequate tire clearance. See Fig. 1.
2. Suspension travel must also be checked. Parts such as brake lines, hoses and brackets must have adequate clearance.
3. New caster eccentrics, rear mounts and nuts must be installed in the front control arms. This change is necessary due to a change in caster specification on vehicles equipped with Porsche 17" wheels. The specification for vehicles equipped with 17" wheels is 3'-15'-45.
See Fig. 2.
4. Vehicles must have a rear stabilizer bar.
5. When adjusting vehicles to new caster specification, all alignment values should be checked at that time.
6. When summer tires are used on vehicles with 17" Porsche wheels, snow chains cannot be used. If winter tires are used, only snow chains with Porsche Part Number 911 361 924 00 may be used.
7. Tire pressures for front and rear 17" Porsche wheels is to be set at 2.5 bar (36 PSI) at approximately 20'C (68'F).
8. When using this rim and tire combination, a 17mm spacer plate must be installed on the rear wheel hub. The customer must be informed that if the emergency wheel is needed, the spacer must be removed.
9. Not for Cabriolet vehicles.
APPROVED WHEEL & TIRE TABLE
Tire size Rim size Offset Position Note
225/45 ZR 17 7,t Jxl7 AH 65mm Front
Summer tires 255/40 ZR 17 9 Jxl7 AH 55mm Rear
(See installation information A through G.)
225/45 ZR 17 8 Jxl7 AH 52mm Front
Summer tires 255/40 ZR 17 94.@ JX17 AH 68nm Rear
(See installation information A through I.)
205/50 R 17 7;-i Jxl7 AH 65mm Front
Winter tires 225/45 R 17 8 Jxl7 AH 52mm Rear
(See installation information A through G.)
NOTE: When using this rim and tire combination, a 17mm spacer plate must be installed on the rear wheel hub. The customer must be informed that if the emergency wheel is needed, the spacer must be removed.
PARTS INFORMATION TABLE
Description Part Number Quantity
Spacer Ring 951 331 611 02 2
Wheel Bolt 904 341 671 00 10
Wheel Nut 999 1 82 003 36 10
APPROVED WHEEL PART NUMBER TABLE
Size Offset Part Number
7;-i Jxl7 AH 65mm 96536212405
8 Jxl7 AH 52mm 96536212601
9 Jxl7 AH 55mm 96536212800
91.@ Jxl7 AH 68mm 96536212805
APPROVED TIRES AND SIZES (SUMMER VERSIONS) TABLE
Size Makes
225/45 ZR 17 Front Bridgestone Expedia S-01 Nl
255/40 ZR 17 Rear Continental Sport Contact CZ 91
NO Pirelli P700-Z
NO Yokohama A 008P
NO Michelin MXX 3
NO or MXX
NO Pilot SX
APPROVED TIRES AND SIZES (WINTER VERSIONS) TABLE
Size Makes
205/50 R 17 89 H M&S Front Bridgestone WT05
225/45 R 17 90 H M&S Rear Continental TS 750 Pirelli winter 210 Performance
SUSPENSION PART NUMBER TABLE
Suspension Parts
1. Rear Mount
Part Number Quantity Required 951 341 023 00 2 each
2. Eccentric 951 341 431 02 2 each 3. Nut (torque to 100 Nm) 900 910 115 02 4 each
END OF ARTICLE
------------------------------------------
ARTICLE BEGINNING
TECHNICAL SERVICE BULLETIN
17 INCH APPROVED WHEELS & TIRES
Model(s): 1987-On Porsche 944 (with M30 option)
1987-On Porsche 944S (with M30 option)
1987-On Porsche 944 T (with M30 option)
1988 Porsche 944 Turbo S
1989 Porsche 944 Turbo
1989-On Porsche 944 S2
Group: 4
Bulletin No.: 9303
Date: September 28, 1993
SERVICE INFORMATION
Concern
Installing 17" Porsche wheels on vehicles previously equipped with 16" wheels.
SERVICE PROCEDURE
Installation Information 1. Front and rear fender well lips must be reworked and/or checked for adequate tire clearance. See Fig. 1.
2. Suspension travel must also be checked. Parts such as brake lines, hoses and brackets must have adequate clearance.
3. New caster eccentrics, rear mounts and nuts must be installed in the front control arms. This change is necessary due to a change in caster specification on vehicles equipped with Porsche 17" wheels. The specification for vehicles equipped with 17" wheels is 3'-15'-45.
See Fig. 2.
4. Vehicles must have a rear stabilizer bar.
5. When adjusting vehicles to new caster specification, all alignment values should be checked at that time.
6. When summer tires are used on vehicles with 17" Porsche wheels, snow chains cannot be used. If winter tires are used, only snow chains with Porsche Part Number 911 361 924 00 may be used.
7. Tire pressures for front and rear 17" Porsche wheels is to be set at 2.5 bar (36 PSI) at approximately 20'C (68'F).
8. When using this rim and tire combination, a 17mm spacer plate must be installed on the rear wheel hub. The customer must be informed that if the emergency wheel is needed, the spacer must be removed.
9. Not for Cabriolet vehicles.
APPROVED WHEEL & TIRE TABLE
Tire size Rim size Offset Position Note
225/45 ZR 17 7,t Jxl7 AH 65mm Front
Summer tires 255/40 ZR 17 9 Jxl7 AH 55mm Rear
(See installation information A through G.)
225/45 ZR 17 8 Jxl7 AH 52mm Front
Summer tires 255/40 ZR 17 94.@ JX17 AH 68nm Rear
(See installation information A through I.)
205/50 R 17 7;-i Jxl7 AH 65mm Front
Winter tires 225/45 R 17 8 Jxl7 AH 52mm Rear
(See installation information A through G.)
NOTE: When using this rim and tire combination, a 17mm spacer plate must be installed on the rear wheel hub. The customer must be informed that if the emergency wheel is needed, the spacer must be removed.
PARTS INFORMATION TABLE
Description Part Number Quantity
Spacer Ring 951 331 611 02 2
Wheel Bolt 904 341 671 00 10
Wheel Nut 999 1 82 003 36 10
APPROVED WHEEL PART NUMBER TABLE
Size Offset Part Number
7;-i Jxl7 AH 65mm 96536212405
8 Jxl7 AH 52mm 96536212601
9 Jxl7 AH 55mm 96536212800
91.@ Jxl7 AH 68mm 96536212805
APPROVED TIRES AND SIZES (SUMMER VERSIONS) TABLE
Size Makes
225/45 ZR 17 Front Bridgestone Expedia S-01 Nl
255/40 ZR 17 Rear Continental Sport Contact CZ 91
NO Pirelli P700-Z
NO Yokohama A 008P
NO Michelin MXX 3
NO or MXX
NO Pilot SX
APPROVED TIRES AND SIZES (WINTER VERSIONS) TABLE
Size Makes
205/50 R 17 89 H M&S Front Bridgestone WT05
225/45 R 17 90 H M&S Rear Continental TS 750 Pirelli winter 210 Performance
SUSPENSION PART NUMBER TABLE
Suspension Parts
1. Rear Mount
Part Number Quantity Required 951 341 023 00 2 each
2. Eccentric 951 341 431 02 2 each 3. Nut (torque to 100 Nm) 900 910 115 02 4 each
END OF ARTICLE
10-03-2003, 11:39 PM
#4
Danno is correct, but most people do not run the updated P/Ns for the caster blocks...matter of fact I think I only know of 3 on the entire board.
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10-04-2003, 07:01 PM
#6
Racer
Thread Starter
The part i don't understand is this:
The specification for vehicles equipped with 17" wheels is 3'-15'-45.
taken from that article posted by Danno. Regarding the parts I already have them and am in the process of installing them
The specification for vehicles equipped with 17" wheels is 3'-15'-45.
taken from that article posted by Danno. Regarding the parts I already have them and am in the process of installing them
