825 replies to this topic

[speedengineer]

So once you do this, you just put the piston back in without the other pieces, right?  Anything else?

 

Any trouble with the infamous C-clip?

 

There's a couple of ways that you could reinstall it.  The most important part to remember is that there is an o-ring on the 'threaded bolt' looking piece, so this has to be reinstalled as it is what keeps your brake fluid sealed!

 

You could leave the bolt piece intact and reinstall, and just remove the guts inside the piston.  Or you could cut the threaded section off of the bolt piece.  Or you could do both.

 

Good tip for how to remove the guts from the piston.  Alan Cross posted this up in a thread a couple years ago, quite a genius method:  Drop the pill down the threaded hole inside the assembly that's in the piston.  Then simply thread the bolt into the piston assembly.  This will push the assembly out from the inside.  So easy.  You can hold the piston in your hand, and just use a pliers on the bolt shaft, doesn't take much force.

 

C-clip is a non issue.  Just use a couple small precision screwdrivers (or other tool with a small tip) that fit inside the holes in the clip.  It comes out easy enough.  You can actually do it with just one screwdriver.

[speedengineer]

I would just order another set of rears and keep the fronts!  Its a 3/2 maybe even 2/1 front front wear vs rear. And the rear price they charged you for the front was likely less! 

 

What i found the first time I did a rear brake rebuild was the "cheap kits" do not include all the seals...of course after i took it all apart as you have. Mazda kits do have everything. 2nd time i did this i left the adjuster and e-brake parts alone and just removed the little hand grenade part in the piston. No ill affects and they have been fine for 3 years now. In fact, leaving the little allen bolt adjuster inside came in handy when a pit mate found one of his rear brake adjusters and bolt was missing during a pad change..."borrowed" mine to back out his piston.

 

I'm using cobalt pads.  Seems most SM cobalt users use xr3/xr5.  I'm trying xr2/xr3, but I don't want two sets of xr2 fronts until I decide that I like that aggressive of a pad compound.  If I decide I want to drop down in compound, then I have wasted money.

 

All of the seals and boots and brackets and pins were in excellent condition on my calipers.  But I don't like reusing important seals like the piston hydraulic seal, so I ordered replacements, which happened to also come with the dust boot.  I just reused all of the other seals and pad clips, etc.

 

I agree, removing just the hand grenade assembly from the piston would be the easiest way.  In fact, I don't think you would even have to remove parts from the caliper body.  Wouldn't even have to mess with the c-clip. 

[Ron Alan]

.

 

I agree, removing just the hand grenade assembly from the piston would be the easiest way.  In fact, I don't think you would even have to remove parts from the caliper body.  Wouldn't even have to mess with the c-clip. 

Yep...much easier the second time leaving everything alone except the hand grenade, piston seal, dust cover and slider rubbers. 

[speedengineer]

Domm,

 

Maybe this car will get done this spring, maybe not! 

 

Original plan was for it to be done by end of March, with a first race in April.  I am a couple weeks behind, but perhaps that timeline is still achievable??

 

Just spent some time looking a racing schedules.  It appears I have more time to finish the build than I thought.  I was mistaken in that there aren't any races (scca regional or majors, excluding blackhawk) prior to the middle of May.  So as long as I can get a test n tune weekend in to shake down the car in late April or early May, it looks like I have about 8 weeks to finish the build.  Should be doable. 

 

Here are all the events for the midwest area for 2016 that I can find info on.

 

Date             Organization       Track
March 19, 2016     NASA GL         NCM
April 9, 2016      NASA GL         Gateway
April 22, 2016     NASA GL         Mid-Ohio
April 30, 2016     SCCA Majors     Blackhawk
May 14, 2016       SCCA Majors     Pitt Race
May 21, 2016       SCCA Regional   Gingerman
May 21, 2016       NASA GL         Road America
June 3, 2016       SCCA Majors     Mid-Ohio
June 17, 2016      SCCA Majors     Road America
June 24, 2016      SCCA Majors     Watkins Glen
June 25, 2016      SCCA Regional   Grattan
June 25, 2016      NASA GL         Gingerman
July 9, 2016       SCCA Majors     Gingerman
July 9, 2016       NASA GL         Autobahn
July 15, 2016      SCCA Regional   Mid-Ohio
July 30, 2016      SCCA Majors     Road America
August 5, 2016     SCCA Regional   Mid-Ohio
August 6, 2016     NASA GL         Gingerman
August 13, 2016    SCCA Majors     Grattan
August 26, 2016    NASA GL         Mid-Ohio
September 19, 2016 SCCA Runoffs    Mid-Ohio
September 22, 2016 NASA East Champ Watkins Glen

October 7, 2016    SCCA Regional   Mid-Ohio
October 22, 2016   NASA GL         NCM
 

[Jim Drago]

I'm using cobalt pads.  Seems most SM cobalt users use xr3/xr5.  I'm trying xr2/xr3, but I don't want two sets of xr2 fronts until I decide that I like that aggressive of a pad compound.  If I decide I want to drop down in compound, then I have wasted money.

 

All of the seals and boots and brackets and pins were in excellent condition on my calipers.  But I don't like reusing important seals like the piston hydraulic seal, so I ordered replacements, which happened to also come with the dust boot.  I just reused all of the other seals and pad clips, etc.

 

I agree, removing just the hand grenade assembly from the piston would be the easiest way.  In fact, I don't think you would even have to remove parts from the caliper body.  Wouldn't even have to mess with the c-clip. 

 

I never had any luck with the cobalts.. seemed like an on/off switch to me and easily locked the tires.  Then there would be 75% of the pad left and they heat cycled out. This was about 2008 when I tried them. Maybe different now

[davew]

You also have Waterford Hills club out of the Detroit area and midwestern Council (www.mcscc.org) based out of Blackhawk

[Bench Racer]

Bring it to BlackHawk to check out and see if the brakes are any good.

[speedengineer]

I never had any luck with the cobalts.. seemed like an on/off switch to me and easily locked the tires.  Then there would be 75% of the pad left and they heat cycled out. This was about 2008 when I tried them. Maybe different now

 

Thanks for the datapoint Jim.  From what I gather, compound choice is very much driver preference.  Regardless, here are my thoughts on pads that I've used.

 

Storytime:

Back when I had my S2k race car (2010-2012), I first used carbotechs, XP10/XP8 I think.  They wouldn't hold up when they got too hot.  They would fade, but never completely go away.  But when they got that hot, they left glazed deposits all over the rotors which caused rough pedal feel.  Easy on rotor wear...except for ruining the rotors when they glazed up.  The carbotechs didn't wear out too fast, but who cares when the performance sucked.  So then I switched to Hawk DTC-60.  Much better for this application, better feel, higher friction, more initial bite which I like.  Though sometimes the backing plates were too large and required filing to fit in the s2k caliper.  Nasty dust that liked to rust onto the wheels, at least back then.  Eventually I tried Cobalts on a friends advice, XR2/XR3.  Loved them, similar friction and bite to the hawks, but the pedal feel was smoother and more consistent.  The pads always fit in the caliper as the backing plate was the proper size.  Didn't seem to get pad taper wear as much, and the pads lasted 50% longer than the hawks. 

 

Then I built my PTE miata for 2013.  Tried carbotechs again, same compounds, same story.  Inconsistent performance, smeared rotors, yuck.  Switched to the hawk DTC-60 again.  Work great, low life though.  The Hawks could do 3 weekends at most tracks, but not worth the risk of running out so I usually swapped after two.  At least on the miata fitment, Hawk skimps on pad material.  I recently measured the compound material thickness of a new hawk to a new cobalt, and assuming you remove pads from the car when they get to 1/8" material left, then the Cobalts had 25% more usable pad material than the hawks. Anyway, I never tried the cobalts on the PTE miata, as Hawk introduced a killer contingency program with NASA, so I've had basically free hawk pads for the last couple of years. 

 

Which leads me to now, I plan to try Cobalts on the miata and see if I like them as much as I did in the S2k days.  I have also heard excellent things about the PFC pads, so I am hoping to try them out at some point this season also.  Perhaps the carbotechs have changed since 2013?  Seems a lot of people do like them too, so perhaps it's worth giving them a second chance.

[speedengineer]

You also have Waterford Hills club out of the Detroit area and midwestern Council (www.mcscc.org) based out of Blackhawk

Yup!  I actually used to live barely over a mile from Waterford Hills.  I have no interest in racing at that track though.  Is MCSCC now doing exclusively Blackhawk events?  I thought they used to venture out to some other tracks?

 

Bring it to BlackHawk to check out and see if the brakes are any good.

Indeed.  I roasted a set of HP+ pads there one time.  Toughest track I know on brakes.  I know for sure the carbotechs won't work at Blackhawk.  At least not the standard compounds most SM drivers use. 

[Tom Hampton]

Hmm....I get better life than that out of my DT-60/30 combo on my NA6 (maybe the extra weight decreases the life on the NB).  More like 4-5 weekends (including a full 6 session test day for each weekend).  Also easy on rotors....about 2 pad sets per rotor pair (fronts).

I used the PFC97 pads until they were announced as discontinued. Without any on-track experience with the new PFC compound I elected to switched to DTC60/30, based on trusted feedback.  Very similar braking characteristics to the PFC97.

[speedengineer]

Hmm....I get better life than that out of my DT-60/30 combo on my NA6 (maybe the extra weight decreases the life on the NB).  More like 4-5 weekends (including a full 6 session test day for each weekend).  Also easy on rotors....about 2 pad sets per rotor pair (fronts).

I used the PFC97 pads until they were announced as discontinued. Without any on-track experience with the new PFC compound I elected to switched to DTC60/30, based on trusted feedback.  Very similar braking characteristics to the PFC97.

Interesting.  Certainly my PTE car had a lot more power than your 1.6, which is likely the difference.  High 130's to maybe 140hp this last season.  2400lbs.  I would also do a lot of events running two classes, so a bit of extra track time.

[davew]

Just as an FYI, the PFC 97 compounds are back. I have about 200 sets on the shelf in both 1.6 and 1.8 fronts and rears. I will be bringing plenty to NOLA in case anyone needs them

 

PFC has agreed to continue making them for me, just as a special order program. SO I have to buy big quantity to have them made.

[davew]

Pad life is very much track dependant. My home track of Blackhawk Farms is considered the hardest track in the country on brakes. 4 threshold stops from 100mph and one from 80mph every lap. We get about 2 hours on fronts. Yet with the same drivers at Sebring, we went 7 hours and still have enough left for a day at Blackhawk. Road America is also very hard on brakes due to the long straights. Lots of speed to scrub off, 120 to 50mph. then the long straights for everything to get ice cold. Thermal shocks everything.

 

What works at one track does not work at every track.

 

Dave

[DrDomm]

Yep...much easier the second time leaving everything alone except the hand grenade...

 

Yeah, seems silly to even mess with the other parts.

 

Just looking at it, I can't figure out if the parking brake would still work when you do this?  Will it?

[Ron Alan]

Nope...without the grenade the rod/bolt has nothing to push on.

[DrDomm]

Nope...without the grenade the rod/bolt has nothing to push on.

 

Ok, wasn't sure that's how it worked.  When I rotated the parking brake actuator, I didn't see the rod/bolt move.  I'll look more carefully today.

[JSmart]

I actually used to live barely over a mile from Waterford Hills.  I have no interest in racing at that track though.

 

Wuss.

[speedengineer]

Wuss.

Yup, pretty much.

[FTodaro]

Hmm....I get better life than that out of my DT-60/30 combo on my NA6 (maybe the extra weight decreases the life on the NB).  More like 4-5 weekends (including a full 6 session test day for each weekend).  Also easy on rotors....about 2 pad sets per rotor pair (fronts).

I used the PFC97 pads until they were announced as discontinued. Without any on-track experience with the new PFC compound I elected to switched to DTC60/30, based on trusted feedback.  Very similar braking characteristics to the PFC97.

I absolutely toasted a set of Hawk DT 60/30's at BlackHawk. The PFC97's are a much better pad there. I could not finish Saturdays race on the Hawks.

[speedengineer]

Restrictor plate arrived today!  Holy crap 38mm looks so small compared to the throttle body.  Only ~44% of the available flow area. 

 

I am happy to report that the diameter of the plate is as it is supposed to be - 0.010" under.  Maybe 0.011", but close enough.  I had been concerned after hearing a few people comment about receiving plates that were 0.020" under.