Anti knock back springs

[M3 Number 86]

Most aftermarket bbk come with these installed and I thought the stoptech trophies did as well but I guess not.

Anyone have experience with purchasing these from somewhere. I've seen some at AP Racing for sale but which springs do you buy? 4/6/9/12 lbs? Just want the lowest spring rate needed to combat excessive piston retraction.

TIA

[roastbeef]

Is it something you can just add? I would think the pistons would have some kind of retainer for the spring...

[TZANIDO777]

https://www.zeckhausen.com/catalog/i...th=24_217_7351

You will need compressed air to push the pistons out so you do not risk scoring the pistons

I have not done this yet as I have not had an issue with pad knockback yet with my trophy kit

[M3 Number 86]

Originally Posted by TZANIDO777

https://www.zeckhausen.com/catalog/i...th=24_217_7351

You will need compressed air to push the pistons out so you do not risk scoring the pistons

I have not done this yet as I have not had an issue with pad knockback yet with my trophy kit

Hmm I wonder how many pounds I would need?

[roastbeef]

Selll that ish and step up.

[M3 Number 86]

Originally Posted by roastbeef

Selll that ish and step up.

All I need are the springs. Otherwise with the endless pads braking was excellent.

No fade, no drop in performance even as it was doing this lol

https://instagram.com/p/Bg9dIhVBizb/

[M3 Number 86]

According to Tito, ap Racing uses 4lb springs. I'll start there.

[TZANIDO777]

Originally Posted by M3 Number 86

Hmm I wonder how many pounds I would need?

Not too sure, your best bet is to call Zeckhausen and ask what they recommend. It could be setup dependent.

[roastbeef]

Originally Posted by M3 Number 86

All I need are the springs. Otherwise with the endless pads braking was excellent.

No fade, no drop in performance even as it was doing this lol

https://instagram.com/p/Bg9dIhVBizb/

holy smokes... drive a little bit my dude!

[dparm]

Originally Posted by M3 Number 86

All I need are the springs. Otherwise with the endless pads braking was excellent.

No fade, no drop in performance even as it was doing this lol

https://instagram.com/p/Bg9dIhVBizb/

Hah, that's happened to me before, too -- if your cooldown is too short, you can definitely pull in with smoking brakes!

[M3 Number 86]

Going with stoptech 4lbs Springs. Strange they sell their own. Just have them installed!!

Another option is the full floating hardware but there is so much chatter.

[RickyBobby]

I've installed knockback springs in all of my stoptech kits and haven't noticed any downsides.

Note, you can use competitors springs and save some money over the stoptechs. Shop around.

[roastbeef]

Originally Posted by dparm

Hah, that's happened to me before, too -- if your cooldown is too short, you can definitely pull in with smoking brakes!

i've also had a piece of rubber slag fall from the inside of the barrel onto/into the rotor/veins. lots of smoke!

[M3 Number 86]

Originally Posted by RickyBobby

I've installed knockback springs in all of my stoptech kits and haven't noticed any downsides.

Note, you can use competitors springs and save some money over the stoptechs. Shop around.

The stoptech springs are like a few bucks now. I saw some older forum threads where they were $27 per spring??

What rates did you go with? Did installing them alleviate knockback? Do I need to buy new seals when I install these?

[RickyBobby]

Originally Posted by M3 Number 86

The stoptech springs are like a few bucks now. I saw some older forum threads where they were $27 per spring??

What rates did you go with? Did installing them alleviate knockback? Do I need to buy new seals when I install these?

I think I have 6lb springs. They help a bit with knockback but don't completely eliminate it. When the pads are worn down I feel like it works less.

I'm actually rebuilding my brakes this weekend but unfortunately sidelined because stoptech sent me an incomplete seal kit

[roastbeef]

are those boots i see on the pad side of the pistons? how do the boots secure to the caliper? snap ring or something?

also, did your pistons come with that raised spring retention cutout in the center, or did you have to upgrade your pistons?

[RickyBobby]

Originally Posted by roastbeef

are those boots i see on the pad side of the pistons? how do the boots secure to the caliper? snap ring or something?

also, did your pistons come with that raised spring retention cutout in the center, or did you have to upgrade your pistons?

The pistons came with the impressions for the spring.
The dust boots have an internal metal ring that press fits into the caliper.

[M3 Number 86]

Originally Posted by RickyBobby

I think I have 6lb springs. They help a bit with knockback but don't completely eliminate it. When the pads are worn down I feel like it works less.

I'm actually rebuilding my brakes this weekend but unfortunately sidelined because stoptech sent me an incomplete seal kit

i got 4 pounders dammit. lol

We'll see how it goes. I'm going to install these today.

For the other improvements, I may purchase the full floating (rattling) rotor hardware. Supposedly those help even more.

I spoke to David from Zeckhausen and he's a pretty cool dude. Even called me when he saw my order because he thought I bought way too many parts for one car but I told him it was for two cars.

[RickyBobby]

Originally Posted by M3 Number 86

i got 4 pounders dammit. lol

We'll see how it goes. I'm going to install these today.

For the other improvements, I may purchase the full floating (rattling) rotor hardware. Supposedly those help even more.

I spoke to David from Zeckhausen and he's a pretty cool dude. Even called me when he saw my order because he thought I bought way too many parts for one car but I told him it was for two cars.

Don't do the floating rotor trick. I tried it and it did nothing for me and rattled so much it over stressed and cracked my mount points.

I left foot tap on the brakes before big corners now by nature and have no issues.

[roastbeef]

Originally Posted by M3 Number 86

For the other improvements, I may purchase the full floating (rattling) rotor hardware. Supposedly those help even more.

i'm running my rear brakes without pad retainers and the noise isn't much, and doesn't bother me. when it happens, i know exactly what it is. really not a big deal.

[jritt@essex]

Originally Posted by M3 Number 86

i got 4 pounders dammit. lol

We'll see how it goes. I'm going to install these today.

For the other improvements, I may purchase the full floating (rattling) rotor hardware. Supposedly those help even more.

I spoke to David from Zeckhausen and he's a pretty cool dude. Even called me when he saw my order because he thought I bought way too many parts for one car but I told him it was for two cars.

The springs are going to have a far greater impact on mitigating knockback than the hardware on the discs will. Four lb. springs are fine...don't worry. With the 18mm thick pads in your kit, they're a good choice. We run both 4 lb. and 7 lb. springs in our front calipers in our Essex/AP BBKs, depending on the caliper. If someone didn't tell you what their rate was, you probably wouldn't know the difference.

Dave Z is a good dude that I've known for about 15 years. He's honest as they come and won't lead you astray.

[Richbot]

You guys ever dynoed drag from springs vs no springs? Assume negligible but would be curious what's there/not there