S4 / GT brake confusion - more pics.
#31
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Rennlist Member
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Possibly because piston shape was changed due to seal type change. Early style pistons have straight outside and dust seal is on caliper side while late style dust seal is partly on piston and partly on caliper. See 1989 S4 service info tech for diagram. Text in it is not absolutely clear but I would interpret it so that same silencers would work on both early and late version as long as pads are thinner asbestos free version.
#33
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The earlier question would have been easily resolved with a picture of the normally visible side of the caliper - raised "PORSCHE" letters means old seals, stuck/painted on "PORSCHE" letters means new style seals with what looks like smaller dia pistons, until you pop the seals off and measure the actual piston and not the sealing groove on the piston.
#34
Nordschleife Master
Each fixed caliper 2x30mm and 2x28mm
The earlier question would have been easily resolved with a picture of the normally visible side of the caliper - raised "PORSCHE" letters means old seals, stuck/painted on "PORSCHE" letters means new style seals with what looks like smaller dia pistons, until you pop the seals off and measure the actual piston and not the sealing groove on the piston.
The earlier question would have been easily resolved with a picture of the normally visible side of the caliper - raised "PORSCHE" letters means old seals, stuck/painted on "PORSCHE" letters means new style seals with what looks like smaller dia pistons, until you pop the seals off and measure the actual piston and not the sealing groove on the piston.
There's a Technical Service Bulletin from '89 that lists the inner and outer dimensions of the various pistons, and you can tell which you have by just taking out the pads and unbolting the brake caliper to get some vernier calipers in there.
I saw it the other day when hunting for similar info.. Bill Ball posted it in this thread here: https://rennlist.com/forums/showthre...+raised+brembo
edit: FYI my calipers have raised Porsche lettering, but are made after the changeover during '89 to the newer piston type. There's a note about the VIN cut-over during '89 in that same service bulletin.
#35
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You can determine the pistons you have by the size of the hollow middle section.
There's a Technical Service Bulletin from '89 that lists the inner and outer dimensions of the various pistons, and you can tell which you have by just taking out the pads and unbolting the brake caliper to get some vernier calipers in there.
I saw it the other day when hunting for similar info.. Bill Ball posted it in this thread here: https://rennlist.com/forums/showthre...+raised+brembo
edit: FYI my calipers have raised Porsche lettering, but are made after the changeover during '89 to the newer piston type. There's a note about the VIN cut-over during '89 in that same service bulletin.
There's a Technical Service Bulletin from '89 that lists the inner and outer dimensions of the various pistons, and you can tell which you have by just taking out the pads and unbolting the brake caliper to get some vernier calipers in there.
I saw it the other day when hunting for similar info.. Bill Ball posted it in this thread here: https://rennlist.com/forums/showthre...+raised+brembo
edit: FYI my calipers have raised Porsche lettering, but are made after the changeover during '89 to the newer piston type. There's a note about the VIN cut-over during '89 in that same service bulletin.
Do you have the front X member out yet ?