BlackHole Posted August 1, 2007 Share Posted August 1, 2007 Was there a running change on the LGT MT rear caliper in '05 (my car mfg 10/04)? My rear caliper pistons measure just less than 32mm in diameter, contrary the 38mm I expected from reading the Archives and Big Brake bias post. Side note - n00b that I am thought I could just plug&play the WRX 17/16" master cylinder for the stock unit. Nope, doesn't work that way - the whole booster assembly has to be swapped over at a minimum since both the way the M/C mounts to the booster and the bolt spacing are different. Oh well, at least it was a cheap failure. Having fun with brake upgrades... Kyle "BlackHole" Link to comment Share on other sites More sharing options...
praedet Posted August 1, 2007 Share Posted August 1, 2007 Interesting... I have not ever seen anything on a running change, and I was going off the Subaru specs... Link to comment Share on other sites More sharing options...
BlackHole Posted August 1, 2007 Author Share Posted August 1, 2007 I wonder if there is a typo in the FSM and the rear piston diameter is actually 31.8mm instead of 38.1, although that would heavily front-bias the braking to the order of ~80%/20% F/R, which strikes me as a bit extreme even for an OEM. Then again, as far as I can tell these are the original calipers on the car and it doesn't look like they've ever been touched. Anybody have a set of rear OEM calipers they can measure? If you are changing rear brake pads or wheels, it'll take just a minute to swing the caliper back and check - the data would be helpful. Hmmm... guess I shouldn't have sold those Brembos after all. Kyle "BlackHole" Link to comment Share on other sites More sharing options...
BlackHole Posted August 6, 2007 Author Share Posted August 6, 2007 bump - somebody else had to have measured their stock LGT rear caliper pistons. Kyle "BlackHole" Link to comment Share on other sites More sharing options...
dasbigunit Posted August 6, 2007 Share Posted August 6, 2007 I have a pair of 05+ LGT Rear calipers i can measure, they are off the car so if you tell me specifically what you want, i can measure for you. coincidentially, I have these because I'm about to replace my tiny a$$ Outback rotors with the OEM LGT ones... Link to comment Share on other sites More sharing options...
BlackHole Posted August 6, 2007 Author Share Posted August 6, 2007 I have a pair of 05+ LGT Rear calipers i can measure, they are off the car so if you tell me specifically what you want, i can measure for you. Thanks - please measure piston diameter and post what you find. Kyle "BlackHole" Link to comment Share on other sites More sharing options...
dasbigunit Posted August 6, 2007 Share Posted August 6, 2007 32mm OD of the circular piston face that pushes on the brake pad. Link to comment Share on other sites More sharing options...
05TurboGT Posted August 6, 2007 Share Posted August 6, 2007 I am about to change the front rotors on my 05 LGT. I found a subaru website that says one rotor part number 26300AG001 fits the 05 LGT models made until 12/04. This rotor weighs 20 lbs. There is a part number, 26300AG02A that fits cars made from 10/04 and beyond???? These rotors weigh 25lbs. Maybe Subaru did have some brake changes during the 05 run. I am going with the heavier rotor since a car made in 11/04 could take either rotor. I should have just taken the money I got from the Subaru lemon law suit and bought a brake kit!! Link to comment Share on other sites More sharing options...
BlackHole Posted August 6, 2007 Author Share Posted August 6, 2007 32mm OD of the circular piston face that pushes on the brake pad. Thanks for checking / posting. Looks like there may be a typo in the FSM. I wonder if there are any direct swaps from other models with the larger 38mm piston. Kyle "BlackHole" Link to comment Share on other sites More sharing options...
strife1012 Posted August 7, 2007 Share Posted August 7, 2007 I think its time for a Proven Failure FAQ Link to comment Share on other sites More sharing options...
Osei Posted August 7, 2007 Share Posted August 7, 2007 question,i don't have a GT, but, why go to a heavier rotor and increase your unsprung weight by 10lbs? O. Link to comment Share on other sites More sharing options...
dasbigunit Posted August 7, 2007 Share Posted August 7, 2007 ^ to increase brake operating reliability, by increasing the size of the heat-sink (rotor), increasing cooling area (rotor), etc... thus reducing temperature during a long, hard, driving session. ie: hill runs, track, etc... i personally have an outback xt, why they put smaller brakes on a car that weighs more and has the same power as the LGT is a mystery. Link to comment Share on other sites More sharing options...
Osei Posted August 8, 2007 Share Posted August 8, 2007 i see says the blind man. O. Link to comment Share on other sites More sharing options...
dasbigunit Posted August 19, 2007 Share Posted August 19, 2007 Well, they bolted on fine, both dust shields are fine to retain, too. I now use: 05+ LGT Front and Rear Calipers, DBA 4000 Brake Rotors for 05+ LGT's Front and Rear (The rear is vented now.) EBC Yellow Stuff Pads for 05+ LGT's Front and Rear Stainless lines for 05+ LGT Front and Rear ATE Super Blue DOT4 Fluid. Piece of cake, just took a while.... These are the brakes that should have coem with the OBXT. Link to comment Share on other sites More sharing options...
sgt Posted August 19, 2007 Share Posted August 19, 2007 I would like to see how much the numbers in the bbk faq change with the correct rear piston size. Link to comment Share on other sites More sharing options...
praedet Posted August 19, 2007 Share Posted August 19, 2007 Well, I am hestitating on doing it because there are quite a few specs based on subaru's numbers. If this is wrong, than there could be a lot more. I need someone to disect their front and rear brakes and take quite a few measurements. Or, I will try e-mailing Subaru for their piston sizes and effective radii... Link to comment Share on other sites More sharing options...
sgt Posted August 20, 2007 Share Posted August 20, 2007 If I still had my stock brakes I would be happy to get you solid numbers. I actually just did a brake job on another legacy and could have gotten solid numbers had i known. Link to comment Share on other sites More sharing options...
BlackHole Posted August 20, 2007 Author Share Posted August 20, 2007 Well, I am hestitating on doing it because there are quite a few specs based on subaru's numbers. If this is wrong, than there could be a lot more. I need someone to disect their front and rear brakes and take quite a few measurements. Or, I will try e-mailing Subaru for their piston sizes and effective radii... What do info you need besides piston diameters? Pad dimensions? I have no reason to believe that the effective disc diameter info in the BBK FAQ is incorrect, the numbers seem within my measuring error. Kyle "BlackHole" Link to comment Share on other sites More sharing options...
praedet Posted August 20, 2007 Share Posted August 20, 2007 Yeah, I'd like to get the front piston diameter too. I don't have LGT brakes anymore... Link to comment Share on other sites More sharing options...
BlackHole Posted January 10, 2008 Author Share Posted January 10, 2008 Help - can someone please check to see if there is a part# change to the LGT rear calipers over the 05-07 timeframe? I'm planning brake upgrades for this year thus reviving this thread. I'd be really happy if I could find a rear replacement caliper w/ a 38mm piston, but there doesn't seem to be any other Suby to swap with that shares this caliper width and mounting pattern. FWIW, my fronts were 42.8mm as stated in the FSM. Kyle "BlackHole" Link to comment Share on other sites More sharing options...
fweasel Posted January 10, 2008 Share Posted January 10, 2008 The pistons in the rear calipers on both my 05 and 06 GT's are 32mm, FWIW. (did you guys get the headphones?) ignore him, he'll go away. Link to comment Share on other sites More sharing options...
BlackHole Posted January 11, 2008 Author Share Posted January 11, 2008 The pistons in the rear calipers on both my 05 and 06 GT's are 32mm, FWIW. (did you guys get the headphones?) Thanks for confirming the piston size. Hmmm, I wonder how I can get a 38mm back there... OT: yeah, we got them. We just didn't figure out what they were until last night. I'll PM you about cost... Kyle "BlackHole" Link to comment Share on other sites More sharing options...
fweasel Posted January 11, 2008 Share Posted January 11, 2008 Are you just looking to increase the rear bias a little? You can always go with the RB adapter kit ignore him, he'll go away. Link to comment Share on other sites More sharing options...
BlackHole Posted January 11, 2008 Author Share Posted January 11, 2008 Yup, a bit more rear bias would be nice. The RB is on my list, but if I can effectively do the same with a cheap OEM caliper swap on the stock rotor that'd leave me more $$$ in the mod budget. Kyle "BlackHole" Link to comment Share on other sites More sharing options...
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