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Old 06-26-2009, 10:05 AM   #1
brandonl
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Default Pad knockback solved!

Im sure many of us have felt knockback before and have decided to just deal with it. Well I was tired of dealing with it, and doing wheel to wheel racing and having to brake hard from high speeds needing to trim 75-100mph with a car inches off both bumpers and having the pedal travel 3/4 to the floor is less than confidence inspring. Since AP, Alcon and other racing caliper companies use antiknock back springs from the factory in their calipers, I figured it was worth a shot. I found sets of 4 springs for 36.5mm+ pistons on HRP's site and they are only $6.90 per set. Calipers off and open, springs in and knockback is gone 100%. I ran my car on NJMP's lightning circuit yesterday and I didnt get even a hint of knockback once, when I typically felt it twice per lap. Go get em guys, thank me later

http://www.hrpworld.com/index.cfm?fo...action=product

Brandon
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Old 06-26-2009, 03:23 PM   #2
Fred
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I thought about getting a set of those for my STi when I had it. Ended up selling it first. How do they install? Does it cause the brakes to drag a little? If not, how does this work?

Good to hear from someone like you that they actually work.

Thanks.
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Old 06-26-2009, 03:26 PM   #3
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yes, they do cause brakes to drag...it gave the spring rate in the link. 6 lbs IIRC.
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Old 06-26-2009, 04:11 PM   #4
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Or you can left foot, tap, tap before you enter your braking zone. I just got used to it and I still have to tap with my 08 WRX. I sure don't miss having to do that on my 06 STi though
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Old 06-26-2009, 04:13 PM   #5
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Quote:
Originally Posted by Homemade WRX View Post
yes, they do cause brakes to drag...it gave the spring rate in the link. 6 lbs IIRC.
6lbs is a drop in the bucket compared to what's exerted under even light braking, though, isn't it?

-Mike
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Old 06-26-2009, 04:24 PM   #6
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I do not feel a brake drag at all. A 6lb spring is so light it is hard to really explain without having felt one yourself. The force is not enough to really apply the brakes just enough to "reset" the pads into position should they shift away from the rotor surface. I can not say for a fact that they do not drag at all, I did not take any steps to measure the drag, but it honestly can not be felt at all. The car rolls across the floor just as it did before, there is no different feeling of resistance when you turn the rotors by hand either.

The left foot tap does work for sure, but I do not like to have to phantom brake check the guys behind me at speed. You are right Phil, NOT having to do it sure feels good.
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Old 06-26-2009, 04:36 PM   #7
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If they're dragging the only thing it'll really influence is the brake wear and it'll be minimal at that. If this is a track only set up brake wear won't really matter as you're changing them out often.
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Old 06-26-2009, 04:48 PM   #8
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Dragging makes it sound worse than it is, whatever amount of drag there may be is nothing you will feel, and on a track car you will never see the difference in the pads service life. 6lbs of force at the pad is equal to an eye lash falling on the brake pedal... not literally, but its as minimal as minimal gets in comparison the force exerted when you actually apply the brakes.
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Old 06-26-2009, 05:08 PM   #9
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Quote:
Originally Posted by grippgoat View Post
6lbs is a drop in the bucket compared to what's exerted under even light braking, though, isn't it?

-Mike
yes, the pressure isn't much but my concern would be more of wear and heat. Though I'm sure those would probably be minimal when you look at the grand scheme things...still makes for a higher pad, rotor and caliper operating temp.

Quote:
Originally Posted by Darks View Post
If they're dragging the only thing it'll really influence is the brake wear and it'll be minimal at that. If this is a track only set up brake wear won't really matter as you're changing them out often.
true but wear items do add up...

We used springs in the formula car one year for the front and noticed some decent heat increase and pad wear.
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Old 06-26-2009, 09:01 PM   #10
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For those who've actually experienced constant pad knock back weekend after weekend - it is a PITA and the tiny increase in pad wear/heat will be worth it.

-Paddy
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Old 06-26-2009, 09:56 PM   #11
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My temporary solution with my 04 STi was to adjust the brake pedal underneath the dash so that there was just a little bit of pressure/ dragging. Worked for all but the hardest cornering side to side at autoxes.
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Old 06-26-2009, 10:01 PM   #12
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I get consistent pad knockback at the auto-x & its driving me crazy. However, I was at NJMP Lightning this past Sunday & I didnt get any knockback. Lightning is a very smooth rhythm based course. So I wonder if the knockback is gone because the course you tested them on doesnt produce much knockback? But I'll give these a try, for sure. Thanks!
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Old 06-26-2009, 10:15 PM   #13
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Also, how are these installed?
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Old 06-27-2009, 05:59 PM   #14
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I agree it is very much rythm based, but I know through turns 3, 4, 5 I generate enough cornering force to feel knockback at the brake zone for the left hander under the bridge. They are installed directly behind/under the piston in the caliper.
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Old 06-27-2009, 06:18 PM   #15
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I solved my pad knockback by installing '05+ parts on my '04. I almost sold my car over it.
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Old 06-28-2009, 11:22 AM   #16
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In hindsight I would have done the same but I already have too much invested in suspension, brakes, and wheels to change the bolt pattern now.
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Old 06-28-2009, 12:14 PM   #17
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We have used them before and always had good results.

For those asking, you have to remove the pistons from the calipers and install the springs behind them.

Tony
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Old 06-28-2009, 12:41 PM   #18
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Quote:
Originally Posted by Element Tuning View Post
Or you can left foot, tap, tap before you enter your braking zone.
Which is a damn good idea to do anyway.
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Old 06-28-2009, 03:30 PM   #19
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Quote:
Originally Posted by brandonl View Post
In hindsight I would have done the same but I already have too much invested in suspension, brakes, and wheels to change the bolt pattern now.
Yeah, that's why I did it before I purchased anything. My '04 spec bearings were starting to feel dead after four hours of track time. I knew that I didn't want to have to go in and change them that frequently, so I just bit the bullet and went through with it.
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Old 06-28-2009, 10:53 PM   #20
iLuveKetchup
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Quote:
Originally Posted by brandonl View Post
In hindsight I would have done the same but I already have too much invested in suspension, brakes, and wheels to change the bolt pattern now.
I agree. Or if I would have researched more & found about the knockback, I would have just bought an 05.
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Old 06-29-2009, 12:53 AM   #21
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Quote:
Originally Posted by brandonl View Post
In hindsight I would have done the same but I already have too much invested in suspension, brakes, and wheels to change the bolt pattern now.
http://www.6gunracing.com/products.asp

2nd one down?

-Mike
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Old 06-29-2009, 09:07 AM   #22
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I tried to go that direction Mike, I dont know whats up with 6gun... I tried calling, emailing and going through a distributor (TIC) with no luck. No returned calls or emails, and TIC said they didnt have any in stock and hadnt had luck getting any kits or a lead time on them.
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Old 06-29-2009, 04:04 PM   #23
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Quote:
Originally Posted by brandonl View Post
I tried to go that direction Mike, I dont know whats up with 6gun... I tried calling, emailing and going through a distributor (TIC) with no luck. No returned calls or emails, and TIC said they didnt have any in stock and hadnt had luck getting any kits or a lead time on them.
Oh well.

-Mike
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Old 10-06-2012, 12:41 PM   #24
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Quote:
Originally Posted by iLuveKetchup View Post
I agree. Or if I would have researched more & found about the knockback, I would have just bought an 05.
I have an 05 I track. What makes the 05 better regarding Knock back?
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Old 10-06-2012, 01:54 PM   #25
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Bigger better hubs.
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