Anyone recall the issues with APR-Tuned (aka 1st Generation Stoptech ST-40) Calipers ?
06-11-2005, 04:42 AM
#12
AudiWorld Expert
The 1st Gen StopTech's had smaller pistons, NOT the 1st Gen APR brakes...
I'm almost positive that the APR brakes (made by StopTech to APR's specs) always had the same piston sizes. StopTech's branded brakes, however, had at least two different versions that had different sizes. StopTech ended up moving to the same size that APR had specified.
So while the 1st Gen StopTech brakes may have had smaller piston sizes, those are not in either generation of APR brakes.
ST Gen 1 != APR Gen 1
So while the 1st Gen StopTech brakes may have had smaller piston sizes, those are not in either generation of APR brakes.
ST Gen 1 != APR Gen 1
06-11-2005, 09:26 AM
#14
AudiWorld Super User
StopTech did have 2 different piston sizes, but their Gen 2 vs. Gen1 is a different thing
entirely, which i think is confusing people. see the link below. their "Gen 2" happened in late 2003 and refers to a new manufacturing process. you can identify Gen 2 calipers by how the bridge bolts attach. Gen 1 bridge bolts were accessed from the inboard, while Gen 2 bridge bolts are accessed from the outboard side. apparently there's a little more clearance with the Gen 2 calipers too.
they changed piston sizes while still using their "Gen 1" caliper. either caliper can use a variety of piston sizes. when i got my StopTechs in 2002, they had already switched to the different piston sizes . . . at least that's what they told me when i asked them.
so it seems there are 3 "versions" of the ST-40 released for the S4:
- piston size 1 w/ Gen 1 caliper
- piston size 2 w/ Gen 1 caliper
- piston size 2 w/ Gen 2 caliper<ul><li><a href="http://www.stoptech.com/press_releases/stoptech_st-40_gen2.htm">Gen 2 press release</a></li></ul>
they changed piston sizes while still using their "Gen 1" caliper. either caliper can use a variety of piston sizes. when i got my StopTechs in 2002, they had already switched to the different piston sizes . . . at least that's what they told me when i asked them.
so it seems there are 3 "versions" of the ST-40 released for the S4:
- piston size 1 w/ Gen 1 caliper
- piston size 2 w/ Gen 1 caliper
- piston size 2 w/ Gen 2 caliper<ul><li><a href="http://www.stoptech.com/press_releases/stoptech_st-40_gen2.htm">Gen 2 press release</a></li></ul>
06-11-2005, 12:10 PM
#17
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FWIW, I gave a set of those away...
...and the recipient made use of the caliper brackets and a few other parts, with some 355s he obtained, but he has several bits remaining. Let me know if you need spares.
06-11-2005, 12:25 PM
#18
AudiWorld Super User
Gen 1 calipers. Piston size . . . don't know, but there was no issue w/ APR's piston sizing.
06-11-2005, 04:07 PM
#19
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Stoptech will give you credit if you wanted to trade to a new freshly painted caliper.
though, i recomend that your mask the inside of the caliper and have it refinished. with either powdercoat or a two part epoxy.
check the powder coat finsish on these HP-2s i rebuilt.
<img src="http://pictureposter.audiworld.com/5084/img_3269.jpg">
I completly diassembled the caliper to rebuild and dust them.
the APR Stg 3 Calipers are excellent, the anodizing just didnt live up.
check the powder coat finsish on these HP-2s i rebuilt.
<img src="http://pictureposter.audiworld.com/5084/img_3269.jpg">
I completly diassembled the caliper to rebuild and dust them.
the APR Stg 3 Calipers are excellent, the anodizing just didnt live up.
06-11-2005, 04:16 PM
#20
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As far as I know, there was only one "generation" of APR StopTechs...
APR had the piston size "right" from the get go. StopTech later changed their own piston size to match what APR had spec'd for the brakes they were selling. APR quit selling StopTechs before the ST40 was revised in terms of the bridge bolts.
APR StopTechs = "old" bolt design and APR piston sizing
Gen 1 Stoptechs = "old" bolt design and "old" piston sizing
Gen 2 StopTechs = "old" bolt design and "APR" piston sizing
Gen 3 StopTechs = "new" bolt design and "APR" piston sizing
It's really not all the complicated, though you can call the Gen 2 calipers Gen 1+ and the Gen 3 calipers Gen 2, if it makes you feel warm and fuzzy.
APR StopTechs = "old" bolt design and APR piston sizing
Gen 1 Stoptechs = "old" bolt design and "old" piston sizing
Gen 2 StopTechs = "old" bolt design and "APR" piston sizing
Gen 3 StopTechs = "new" bolt design and "APR" piston sizing
It's really not all the complicated, though you can call the Gen 2 calipers Gen 1+ and the Gen 3 calipers Gen 2, if it makes you feel warm and fuzzy.