37 replies to this topic

[Bench Racer]

Don't recall ever reading a thread/posts on brake pad kickback. With our Miatas we have all had brake pad kickback. At sometime pad kickback has eaten our lunch. I went back to the Roger Caddell AIM data online class video & watched the video to catch his comments on the normal brake pressure data & the not so normal brake pressure spikes from his Spec Miata. Per Roger this brake pressure data spike was not a brake pedal induced spike.

I have thoughts for kickback causes & am always interested in learning others thoughts for kickback causes. Ideally one could eliminate the root causes for pad kickback. < With this thought we must remember we have an OEM single side piston. I also have sketched a schematic with parts list to build a pad kickback dash warning light system.

[pat slattery]

PUMP THE BRAKES!

[Glenn]

PUMP THE BRAKES!

Watch ANY SM race and you will see all of the front runners reseating the brakes BEFORE the brake zone. Ask MEAT what happens when you forget cost him a top 10 at the runoffs

[Jim Drago]

If you do not have pad kick back, your calipers need to be gone through or replaced, regardless of whether you have the E brake adjusters removed or not. If your calipers are free, like they should be, you will need to set the brakes. I don't think a warning light is worth the time or effort. Repetition for a few sessions and muscle memory will take over. It is hard for most who are used to setting their brakes not to set them at this point. Ever drive behind the Pombos? It looks like Christmas lights going off before each corner.

[Caveman-kwebb99]

Pad Knock back is track specific IMO. I have never experienced this at Mid Ohio in a bazillion laps, but I have experienced it at Road Atlanta. And since I had never had it before I was not one to set the brakes. It almost cost me dearly in T1 at ATL, went to pass lapped traffic and whoooooh where is my brakes. luckily I was quick enough on pumping the pedal to get the car settled down for the turn in but I nearly gave myself a heart attack which for a guy in mid 40's is scarey enough.

[john mueller]

If you do not have pad kick back, your calipers need to be gone through or replaced, regardless of whether you have the E brake adjusters removed or not. If your calipers are free, like they should be, you will need to set the brakes. I don't think a warning light is worth the time or effort. Repetition for a few sessions and muscle memory will take over. It is hard for most who are used to setting their brakes not to set them at this point.

I never experienced being behind someone who set their brakes until the 2011 NASA Nationals, where strangely I found myself in the top half of the field (thanks rain)... The first time the guy ahead of me set-'em (going into China Beach) I jammed mine on thinking there it was the beginning of a wreck. After he did it for the next few laps I caught on but I did not have the need to do it.

Flash-fwd to three weeks ago I had my first experience of BP Kickback while testing at the Streets Of Willow. Only took a few laps to realize what was happening & why, a few quick taps of the BP with the left foot while still at WOT did the trick. So I agree with Jim about muscle memory... I'd never set the brakes before and in two laps it was automatic and I did 120 test laps that day.

[Speedycrw]

If your brake components are free as Jim describes, and you want to experience kicback, just run the line at Road America... you will soon be setting brakes like a pro, or running into the kitty litter!

[Bench Racer]

Watch ANY SM race and you will see all of the front runners reseating the brakes BEFORE the brake zone. Ask MEAT what happens when you forget cost him a top 10 at the runoffs

Point made, thank you.

I know a guy that lost the F production 2011 June Sprints on the last lap because in the heat of the race with SuperMan & Kevin he didn't re-set the brakes before T8 after taking the point at T5. He finished 3rd. He has pretty good muscel mass/memory.

We have other warning lights to cover brain fade when we don't peek at our gauges.

[jaje]

I've been reading up on this issue for the past week - so we need to pump the brakes lightly to set the pads before any hard braking corner (on the straight or before the normal brakezone? This is regardless if we have the e-brake adjuster removed? Kind of reminds me of when I would have to use a 20/80/20 braking trick to settle a car with bad brake dive (nose would dive if I would hit the brakes immediately causing very quick lockup - unless I settled the nose before braking hard).

Please note I've never had to do this with my 944 so this is new to me.

[Bench Racer]

Please note I've never had to do this with my 944 so this is new to me.

I don't know ZIP about a 944 Spec car. Did the 944 Spec calipers have pistons on both sides of a caliper or did the calipers have a piston on one side of a caliper like a Miata?

[jaje]

Fronts and rears were single piston calipers - rears were not vented rotors. Parking brake was an internal drum type and not a locking mechanism of the piston. Not sure if that helps. I'm now concerned as I learn to drive this car that I need to be different on the brakes and check them before each session on track.

[Bench Racer]

When driving you 944 Spec did you reguluarly run across the track corner apex rumble strips & then at the next corner when using the brakes have a long pedal (pedal went closer to the floor before the brakes started doing the job)?

[naparsei]

The problem with the long pedal for me was that it made H/T downshifting hard (read: nearly impossible). A quick (and gentle) LFB helps.

[Qik Nip]

Pad Knock back is track specific IMO. I have never experienced this at Mid Ohio in a bazillion laps, but I have experienced it at Road Atlanta. And since I had never had it before I was not one to set the brakes. It almost cost me dearly in T1 at ATL, went to pass lapped traffic and whoooooh where is my brakes. luckily I was quick enough on pumping the pedal to get the car settled down for the turn in but I nearly gave myself a heart attack which for a guy in mid 40's is scarey enough.

I agree with Kyle regarding Mid Ohio not having the knock back issue. The first time a non-local set his brakes (at the 400' foot marker at T7) in front of me I figured he was just clumbsly trying to brake check me. When he continued to do it at the next three turns, I finally figured it out.
Rick

[wheel]

Some of the kick back comes from the height of the rumble strips, as well as other factors. It has become a habit, no matter which car I am driving and no matter which track. At some time, just before the braking zone, I whack the brake pedal with the left foot. I don't even think about it, just do it automatically.
90+% of the time it is not needed. But when you need it, it saves your ass.
wheel

[davew]

Certain tracks seem to have a lot of problems in this area. Rd Atlanta has it some what, but Road America is the king.

My theroy is that it is all in the rumble strips. Not just crossing over them, but actually running on them for any length of time. If you run on the rumbles at Road America you will have a long pedal. Maybe no pedal. Canada corner seems to be the worst. We have had several wrecks due to people not resetting their brakes.

Dave

[jaje]

When driving you 944 Spec did you reguluarly run across the track corner apex rumble strips & then at the next corner when using the brakes have a long pedal (pedal went closer to the floor before the brakes started doing the job)?

We used all apex and trackout curbing we could to keep up momentum. The next corner brakes were perfectly fine and didn't require extra long travel.

[Brian Linn]

....Road America is the king.

My theroy is that it is all in the rumble strips. Not just crossing over them, but actually running on them for any length of time. If you run on the rumbles at Road America you will have a long pedal. Maybe no pedal. Canada corner seems to be the worst. We have had several wrecks due to people not resetting their brakes.

Dave

+1 - Road America is the only track where I've had the pad knock back on a regular basis. The first time it happened I didn't know what was wrong. Eventually you get in the habit of giving the pedal a pump after you feel the rough ride of the rumbles, as others have described.

I thought someone had explained that the cause was spindle flex as you go over the rumble strips, but my memory could be wrong.

[pat slattery]

Seems to me there should be some permanent fix to a definite safety issue. Either some form of a fix for the existing brake, or we should be allowed a retrofit the brake system.

Wouldn't it be better to fix a problem, rather than mandate items to protect the driver from injury if they wreck.

[Cy Peake]

The rumble strips coming out of West Bend and the Downhill at Lime Rock do it to my car(s) regularly. I had a "moment" my rookie season going into Big Bend and have been a left foot tapper ever since.