AP Sprint kit durability in road salt/magnesium chloride
 

I'm considering purchasing the AP Sprint kit. My car is used on the track and I find myself having to rebuild calipers frequently. Dust boots crack and thinks just don't work smoothly.
I realize I am in a situation that requires compromise. I either:
1. Rebuild OEM calipers frequently and deal with overheating brakes
2. Buy some other BBK with dust seals and hope they don't need frequent rebuilding
3. Buy the AP Sprint kit and hope the mag chloride doesn't destroy them
I spoke with the engineer at AP yesterday and he said they don't have any long-term testing with the kit in salty environments. I live in CO and it's mostly dry here during the winter. But several times each winter we'll see enough snow that they spray mag chloride on the roads.
I'm not asking anyone here to theorize how they will hold up. I'm looking for people that have first-hand experience with this kit that has run it year-round in an area where roads get salted in the winter. Can anyone share their experiences with me? I generally keep my cars for a long time and want to ensure I'm not abusing parts.

Have you considered the Stoptech 328x28 BBK? It has dust boots that seem to hold up to track use. Would be my choice for a BBK that will be exposed to salt.

http://www.ft86club.com/forums/showt...52#post2721252

Thanks, DarkSunrise. I did see some of those posts, but not all of them. When I learned they use dust boots I just dismissed the StopTech kit. Hmm...maybe it's time to reconsider.
What are the chances the StopTech boots will last as long on track as the OEM caliper boots last on the street? I realise they look good after 17 track days, but that could be one season for me. It could be they start to crack after 20 track days, at which point I'm still rebuilding them nearly annually. I'd be really interested to see how the ST boots hold up over 50+ track days.
Again, thanks for the help, DS!

Hmm 50 track days is a lot. I don't think @Sleepless is there yet since he had 17 track days on his Stoptechs as of August this year. Seeing his dust boots holding up with JRSC and XP12's is encouraging though.

@AZP Installs uses the same Stoptech ST40 kits in their shop car and Spec86 car. Wonder if they're closing in on 50 track days with them and can report on the condition of the boots.

Thanks again, DS. Yes, knowing Sleepless has much more power than I do helps me feel better about it. Especially knowing I'm in Denver and make less power than stock up here. I appreciate you introducing those two guys into this thread. Hopefully they can give me some real world feedback.

No problem - hopefully didn't derail your thread by introducing discussion of the Stoptechs!

I just didn't think you'd find many people who had bought $2000 AP Sprints and ran them for extended periods through salt. I guess you never know though. :)

Closest I can help is noting they show minimal signs of issues from early spring ventures where the winter crap is still being washed away. There is surface buildup on some of the bolts and on aluminum parts of my coilovers, but when I pulled everything apart to inspect the guts seemed OK. I didn't disassemble the calipers, just pads out and inspected.

That said, I'd be wary. On the other hand, you're probably doing a full bleed in the spring if not flush... Why not just swap to OEM for winters? With that much track time it seems a small time investment to avoid the compromise entirely.

Also, word from someone that drove Stoptechs and a couple weeks later my Sprints... AP Sprint is better. :) not to mention lighter.

Thanks, cjd. I have considered running OEM in the winter and swapping to AP in the summer. At first blush it seems a little silly or overkill to me, but I suppose it's not all that crazy.
Also, thanks for the Stoptech/AP comparison. Do you know what they liked better about the APs? Light weight is certainly appealing to me.

I believe it was pedal feel and ease of getting just the right pressure... All the way to locking hem up. Pads may also be different, I have AX6. That could be a lot of the difference.

I agree on the OEM swap sounding a tad crazy but I may be doing it this year... my wife informed me she doesn't trust her car for the holiday trips. (10+ year old Prius... It should be fine but has had some starting issues I think were 12v battery related, as a tender seems to have fixed them...) It's just work though, and gives you an easy season to send the AP off for a refresh when it's time for that. Form the number of track days you do, it doesn't strike me as substantial extra work being what you might already be doing. The appeal of not bothering is also clear...

On that note, Pat why not just get a winter beater? The brakes won't be the only thing exposed to mag chloride, not to mention that driving in winter exposes your car to other drivers who might not be able to stop (I might be an AZ boy, but have visited ND several times mid-winter and seen some shit).

A winter beater as an alternative to a $15,000 car? Many would consider a $15,000 car the winter beater. Let's face it, we basically drive economy cars that handle really well and are a ton of fun. I'm not going to buy a second car so I don't have to expose a Subaru to winter conditions. it's not like it's a fancy car. Besides, although it is terrible in the snow, it sure makes for some fun times! :D

@dp1 lives in a winter type environment.

We also have a CSG-Spec Brembo GT kit that should be coming in soon. This uses the Brembo GT caliper and a 1-piece rotor (326x30). The Brembo GT kit is spec'd by CSG and built by Brembo for this specific platform. Brake bias is near stock, much more so than the Essex AP Sprint Kit, which happens to have the closest brake bias to stock compared to any other available kit on the market. Thanks!

Good to know, thank you. And thanks for bringing dp1 into this. Forgot about that guy. I'm looking forward to what he has to say.
I'm hesitant to go with a one-piece rotor, but won't outright say I will not use them. It seems silly to me to go with a BBK and not go for the lighter two-piece option. Maybe I'll give you guys a call this week to talk about it.

I used AP Sprint in salty North East winters and I saw some corrosion on pistons but did not affect performance during the winter or after the winter throughout the entire North East track season following the winter. Piston boots (don't exist on AP Sprint) will disintegrate under track conditions so why bother unless you change them before every winter (not trivial). I don't drive my car in salty winter conditions anymore (no longer a daily and garaged during the winter), but for a tracked daily I would still go for the Sprint kit to get the track performance and just rinse the calipers (or car wash) as often as you can during salty conditions. Even if you don't, it won't be too bad. Either way, rebuild once every 1-2 years to be safe, at around $250 or so with shipping. Others may know better, this is what I did and would do.

On rotors - one-piece, two-piece, who cares unless you're chasing rainbows ;)

ok i understand CO winters are a total different beast than winters in MA, but with winter tires this car is awesome in the snow. Unless we are talking rural roads where you might need more height. I've never seen anyone say these cars were bad in the winter with good winter tires.

Yes, in deep snow low ground clearance often makes it known especially due bulldoser shaped front bumper that seems made for digging in, instead on sliding above. But no traction or control issues with good winter tires, business as usual.

Yeah, 'terrible' is a bit harsh, although you do still have to keep in mind that it's a lightweight, rear wheel drive car with very little weight on the rear. The Torsen definitely helps though, and 4 snows are mandatory. That said, I go pretty much anywhere our Jeep goes, ground clearance not included.


I was considering upgrading to the Wilwood WRX kit (12", 4 piston) in the front, but the way salt is so aggressively used here in central New England, durability of the caliper and rotor hat is a concern. The caliper uses dust boots, but they pretty much pave the roads here with salt from December to April...




EDIT: I apologize for the partial derail...this doesn't have much to do with calipers without dust boots...still curious about durability of other anodized components though...

I don't have the Sprint kit but I've got the RR Racing Sport Performance kit which I'll be running this winter. It uses a single piece rotor so I don't expect issues there but the caliper is anodised and doesn't have dust boots so that is what I'm concerned about although it does use stainless steel pistons which should be better than nothing. Our roads are heavily salted and rust is a big problem here so it will be interesting. I'm doing my winter car prep this weekend and I'm planning to swap pads and do a final partial bleed as part of that process so I'll be taking lots of pictures and notes on the current state of all of the brake hardware and then I'll compare it again in the spring.

Problems with corrosion in salty environment usually are not that much affected what finish or what metal is used in brakes parts, rather that there are different metals placed next to each other. As in two piece disks, as in aluminium calipers (and yes, including stainless steel pistons). Throw in electrolyte, which is from salt+thawn snow/ice, and you get corrosion. Frequent washing may lessen it, but not prevent.

StopTech used to have a document on their website where they said this.

Why aren't these higher end caliper companies using ceramic pistons?
A Chrysler mini van comes with ceramic pistons...

Based on all the frozen ChryCo calipers I've replaced, I don't think ceramic pistons would help much...lol

I think they'd help a great deal with limiting heat transfer into the fluid.
I can assure you it's not the material causing them to freeze.

Pat, did you ever end up getting the sprint kit? And run them through the winter? How did they hold up? I'm in a similar situation

Your timing is good, thpark93. I have run the Sprint kit through two winters now, and plan to clean inspect the calipers sometime this week. At the end of the first winter I cleaned them with Flitz Metal Pre-Clean and a small brush. I'm told that is an excellent remover of mag-chloride. I'll post pictures in this thread when I clean and inspect them soon.

Thanks Pat!

Your posts have been very helpful lately!

Mark

Sent from my Pixel 2 XL using Tapatalk

I ran the RR Racing kit for 2 winters and it's still in good condition although they are filthy and the dirt is more difficult to clean off than I have time/patience for right now.

Due to this website not allowing large photos to be posted, and the benefit that high-resolution photos provide in this situation, I'm not going to add them to my album on this website. Instead, you can see the full-res photos here. Hope that helps.

Pat: i'd be more interested to see not cleanliness from outside .. but rather how insides of calipers/pistons look with pads removed after salty winters. Even if corrosion from outside occurs, it would be more of cosmetical issue. But if they start leaking or if pistons start sticking/dragging, that's what i'd be more wary off. Also may i ask to disassemble one rotor for better look, where iron & alu hub meats up?

@Pat imgur.com

The pistons got a little sticky after one year. I spoke with Essex about it and they said it was totally normal. I use a spreader to push the pistons back in and it works just fine. No leaking is apparent.
I replaced the rotor rings a few days ago. The aluminum/iron interface is perfect.