Last weekend at Vir's south course, going into turn 1, the rear of the car felt kinda light & skippy. If not familiar with the course, this is a medium length straight hitting about 125mph with 2nd gear right hand turn just over a small hill crest so hard braking up the face of a small hill. Similar feeling, more subtle, going into Oak Tree (lower speed, down hill).

The car is a street legal track toy, partially stripped with rear cage and stock brakes. I'm trying to decide if the suspension could be adjusted a tab to keep the rear better planted (jrz rs) or if perhaps I'm using too aggressive compound in the rear. Is anyone else, with a heavy-ish car, using these hawk ht10s on all four corners or using a different compound for the rears (ht14 or hp+ perhaps)?

So you are currently using stock pads, and thinking of jumping to ht10s? That is a huge jump. Why not start out with some HP+ and work your way up. What tires are you running?

Sorry, currently using ht10s on all four corners. Tires are 235/40/17 Toyo RA1s.

I'm better that he's on HT10s already. I've never heard of someone using street pads and the JRZ track setup at the same time. :D

I've used HT10s all around on my car and haven't experienced what you're talking about, but lots of people have. HT14s front and HT10s rear is a pretty common "stagger" for Hawk pads.

I ran HT-10s at both ends. Don't remember any serious issues but I did like the HT-14/HT-10 (f/r) setup better. I'm now running Cobalt Friction XR2/XR3 and I like their performance even better. Got 'em thru Adrelaline Racing. Not sure about longevity or issues such as being caustic yet.

Jay

Getting a bit OT here....I ran HT14/HT10 combo and the HT14s take a bunch of heat to get them gripy. DOwn right scary for a few laps. Still running the 10s in back, but switched to PFC01s in front. I will switch to the PFC01s in the rear when they need replacing.

Commonly people run a more aggressive pad in the front, but some people run all 4 the same. Really comes down to personal preferences.

i did 4 days on south course this year with ht-10's and ra1's, and i never experienced what you are describing.

Worn RTAB's?

Also not sure how much experience the OP has, but I found that until I got up to around 10 days of DE that the rear end always felt a little "light" in very hard braking zones...

After having some great instructors and talking about what I was feeling I eventually realized that I did not have the best braking form. I found that I was making two mistakes, one I was coming into the pedal light , and increasing pressure as I got deeper into the braking zone. Two, I was not settling the car as much as I should have prior to braking. The second issue was very noticeable in Turn 14, just after bishop's bend, at Sebring.

I started working on proper threshold braking, hard into the pedal initially and letting out as you approach the turn in, and getting much faster at getting the car settled prior to getting on the brakes. In most cases now I know how good of a job I've done with my braking and car settling prior to braking by how the car feels when I'm 10/10 braking.

When I jumped up to true track pads, HT10's, with my UUC wilwood kit I had absolutely no problems modulating the better pads, or problems with the rear end feeling "light."

+1 for the HT14/HT10 combo.
Plus you might try a bit more rebound on the rear shocks as you suggested. It's easy to test and change.

My M3 is more or less stock (i.e. heavy and wallowy) and the bias is just the way I like it with HT10's front and rear and 235 RA1's.

Krista,

I think your issue is more related to suspension and/or driving style.

Brakes - driving the same car you have...and having to change pads at the track....my prescription:

HT10's on the Front
Advance Auto Parts Specials on the Back

Just got back from 300+ Hard/Fast(in my mind) miles at Road Atlanta.

I love this combo....is this the BEST brake pad set-up...HECK NO!!...but I only have to change out the front pads before driving home.

Knowing the car is new to you..I'd say drive the heck out of it..then drive some more....and don't change anything...until you are familiar with the car on the specific track.

This way you can narrow down/attribute a behavior of the car to the car, you, the track etc...

Good Luck!!!

From my experience I have found that using ht-10's on all four corners will cause the rear brakes to lock up before the front so try either putting blues on the rear or put ht14's on the front. The same goes with the new dtc pads. use dtc 70's on the front and dtc 60's on the rear.

Krista,

I think your issue is more related to suspension and/or driving style.

Brakes - driving the same car you have...and having to change pads at the track....my prescription:

HT10's on the Front
Advance Auto Parts Specials on the Back

Just got back from 300+ Hard/Fast(in my mind) miles at Road Atlanta.

I love this combo....is this the BEST brake pad set-up...HECK NO!!...but I only have to change out the front pads before driving home.

Knowing the car is new to you..I'd say drive the heck out of it..then drive some more....and don't change anything...until you are familiar with the car on the specific track.

This way you can narrow down/attribute a behavior of the car to the car, you, the track etc...

Good Luck!!!

Not the first person to say this :) I think I may try it. Or Go with HT10s up front and I have a set of HP+ and a set of EBC YellowStuff for the rears.

But people say HT10 up front and some sort of "OEM replacement" rears :) hehe

I have a stock-ish heavy E36 2-dr and I had HT10s F/R with ZERO issues.

As others have said, check/increase rebound a touch in the rear and check for worn/sloppy rear suspension parts, esp RTABs, that make the rear squidgy under heavy braking.
From my experience I have found that using ht-10's on all four corners will cause the rear brakes to lock up before the front so try either putting blues on the rear or put ht14's on the front.
I never had that problem, but my car has full interior and amenities with close to 50/50 weight distribution. But you could easily have problems once you strip it.
The same goes with the new dtc pads. use dtc 70's on the front and dtc 60's on the rear.
That's the combo I have now and LOVE them. Braking consistently is very easy since pedal force is just right - not light, not heavy, and initial bite is crisp and firm with nice, easy release characteristics.

I have found that having a slightly less aggressive rear pad helps when running the stock brake setup. So either going to the HT14's in the front or moving to the blues in the back may help. Its really driver preference though and it depends on how you are using your brakes. If you like to trail brake deep into the corner having the less aggressive pad in the rear usually makes this easier.

A slightly less aggressive rear pad makes the car more stable not faster or better. HT-10 all around will be fine on a car that has a front biased stock setup. The ABS will be kicking in before the car gets really unstable anyway. My car is horrible with more pad on the front than the rear, but it doesn't affect the overall stopping distance that greatly, maybe 15-20 yards at the most.

Side note: my braking is unnerving to many people that ride along but normal to Seth Thomas.

Worn RTAB's?
Funny you mention those, just had them replaced before this event so am thinking that's not the cause. If so, really need to have a chat with my shop.


Krista,

I think your issue is more related to suspension and/or driving style.

Brakes - driving the same car you have...and having to change pads at the track....my prescription:

HT10's on the Front
Advance Auto Parts Specials on the Back

Just got back from 300+ Hard/Fast(in my mind) miles at Road Atlanta.

I love this combo....is this the BEST brake pad set-up...HECK NO!!...but I only have to change out the front pads before driving home.

Knowing the car is new to you..I'd say drive the heck out of it..then drive some more....and don't change anything...until you are familiar with the car on the specific track.

This way you can narrow down/attribute a behavior of the car to the car, you, the track etc...

Good Luck!!!
Airdoc, this is kinda what I was wondering about ... maybe a less aggressive pad in the rear and was kinda looking for an informal poll of responses as to the number of mixed ht10 v. ht10 all around for judgment. I'm less eager looking to suspension setup changes if am making 'fundamental' equipment choices that might exacerbate problems.

The suspension setup seemed perfect for CMP but VIR's south course introduced a little more intense braking zones, imho. For CMP, all was perfect (loved it), and I'm really looking for minimizing the number of variables between tracks at this point in my suspension education. With VIR South being the first new track, post suspension setup, I wondered if maybe I should re-examine my brake pad choice in light of others' experiences.

As for braking technique, I think that my pedal method is 'short, to the point, and with emphasis on stopping'. 'Reach for the radiator' is sorta my motto - not to say that there isn't room for improvement.

I've received quite a few pms & noticed a trend in here concerning pfc pads and am more than willing to give them a try. (after these hawks have served their full time) I hope that I didn't over-exaggerate with the instability comment - the car was stable and perhaps I seemed to exaggerate with the skippy description. The car was controllable at all times and I'm really looking for solutions to increase the stability at the edge. Thank you all for your comments & thoughts.

Funny you mention those, just had them replaced before this event so am thinking that's not the cause. If so, really need to have a chat with my shop.
Did they do an alignment on the car afterwards? If they did what were the rear toe specs?

Did they do an alignment on the car afterwards? If they did what were the rear toe specs?
That's what I was going to ask, too...

If the car feels darty you may just be a click away on the shocks if the mechanical side of the alignment is proper. The adjustment there can help you control how the car feels when you go from acceleration to full deceleration and also how the car reacts to the bumps in the pavement as the speed comes down. You may want to adjust the toe settings from the baseline if you can't get the car back in line with the shocks. Seems like you are pretty close and it won't take that much to get it back.

I doubt the HT-10 is the issue, they are pretty user friendly. CMP is also alot slower and smoother overall that VIR I think.

Rear toe is -1/16.
and while on alignment settings, here are the other settings... the rest...
Frnt Camber= -2.4
Rear Camber=-2.4
Frnt Cast=7
Frnt Toe=-1/16
Rear Toe=-1/16

Thank you guys. I really appreciate your insights and responses. I'm trying learn as much as I can about what the car is doing, why it's doing that, and how I can adjust car & driver to make us faster (and safer).

Got a bit too much rear camber, I'd say. That can cause you to lose a bit of contact patch, esp under hard braking where the rear suspension actually picks UP from the brake torque.

So for most cars the static weight distribution is not 50/50, it's front heavy. Under heavy braking even 50/50 cars are not 50/50. Unless you have adjustable brake bias your front pads are doing more work and likely run hotter. So where's the logic using the same pad front and rear? Simply due to rotor and pad size? Has anyone done temp measurements (more than once, multiple pad types, etc) to show that the rear brakes attain the same temps, or ranges even, as fronts? Without any of that info I never understand why one would adjust the suspension settings to stablize the car when simply switching pad compounds is the more logical solution.

I'd been using HT10's on my JS M3 for awhile before they became publicly popular many years ago and I tried using them on all 4 corners initially. It friggin' sucked bad. Way to grabby in the rear (try high speed trail braking or worse, a quick tap/transition corner), wear more, and it was unbelieveable how much of a push it created in any corner that was flat or even slightly off camber.

I did back to back tests of HT10's in the rear vs Blues and R4's (no, I did not collect temp data, I simply switched pads because this happened during a weekend). The HT10's in the rear were the only pads which caused any of the above conditions. This was discussed way back then too and it was also suggested to adjust the suspension to help compensate for it. Since the JS car did not have that I couldn't do it anyway but I still don't understand the logic of adjusting the suspension to adjust for a brake pad issue. If there is plenty of evidence that it's more than just brake pad, fine, go for it. But adjusting the suspension and saying "there, it's fixed" without any other testing or evidence seems pretty silly to me.

Makes good sense Jack. Plus you could save money on less expensive rear pads. I may have to do some experimenting. Nothing scientific, just butt dyno stuff.

Jay

Makes good sense Jack. Plus you could save money on less expensive rear pads. I may have to do some experimenting. Nothing scientific, just butt dyno stuff.

Jay

Are you saying the butt dyno is not scientific?

Are you saying the butt dyno is not scientific?

For people who know their cars very well or have gotten pretty skilled at noticing the differences when they make changes to their car (I'm not talking about 1 click on a 15 position damper) the butt dyno is certainly a lot more scientific than no testing.

Being a test engineer with a dozen years of automotive testing (including subjective measurements) there are people who are naturally talented at this type of testing, those who can learn it, and those who never will no matter what. I guess the effectiveness of the butt dyno relies at least partly on this. ; )

So for most cars the static weight distribution is not 50/50, it's front heavy. Under heavy braking even 50/50 cars are not 50/50. Unless you have adjustable brake bias your front pads are doing more work and likely run hotter. So where's the logic using the same pad front and rear? Simply due to rotor and pad size?
Having the same pad at all 4 corners works in some cars and doesn't work for others. On top of that, it works for some drivers and not for others. It really just depends...

For people who know their cars very well or have gotten pretty skilled at noticing the differences when they make changes to their car (I'm not talking about 1 click on a 15 position damper) the butt dyno is certainly a lot more scientific than no testing.

Being a test engineer with a dozen years of automotive testing (including subjective measurements) there are people who are naturally talented at this type of testing, those who can learn it, and those who never will no matter what. I guess the effectiveness of the butt dyno relies at least partly on this. ; )

I see what you are saying but I was just making a joke :)

I can certainly say I have changed some items that my butt said made a difference ;)

Having the same pad at all 4 corners works in some cars and doesn't work for others. On top of that, it works for some drivers and not for others. It really just depends...

Unlike low percentage suspension changes, weight distribution changes, etc I think this is only really true if the driver has tested mutiple combinations in multiple situations to understand the differences. There are many people over the years that have said "it works for me" until they finally try something else and find out what they had was fine but not good or great. I'd call this a plateau effect.

I would agree that it is likely not as bad in some cars vs others, weight distribution (dynamic), suspension geometry, brake bias (even stock), etc will all affect this. Point is still that without any testing this is not much more than throwing darts at a board.

Certainly there is driving style differences that will influence it. For example, if I never trail braked I might not have felt the HT10's on the JS car were too bad. If my car weighed 1000lbs more it might not matter as much either. I'd just rather do at least a little experimenting to learn a bit more.

So for most cars the static weight distribution is not 50/50, it's front heavy. Under heavy braking even 50/50 cars are not 50/50. Unless you have adjustable brake bias your front pads are doing more work and likely run hotter. So where's the logic using the same pad front and rear? Simply due to rotor and pad size? Has anyone done temp measurements (more than once, multiple pad types, etc) to show that the rear brakes attain the same temps, or ranges even, as fronts? Without any of that info I never understand why one would adjust the suspension settings to stablize the car when simply switching pad compounds is the more logical solution.

I'd been using HT10's on my JS M3 for awhile before they became publicly popular many years ago and I tried using them on all 4 corners initially. It friggin' sucked bad. Way to grabby in the rear (try high speed trail braking or worse, a quick tap/transition corner), wear more, and it was unbelieveable how much of a push it created in any corner that was flat or even slightly off camber.

I did back to back tests of HT10's in the rear vs Blues and R4's (no, I did not collect temp data, I simply switched pads because this happened during a weekend). The HT10's in the rear were the only pads which caused any of the above conditions. This was discussed way back then too and it was also suggested to adjust the suspension to help compensate for it. Since the JS car did not have that I couldn't do it anyway but I still don't understand the logic of adjusting the suspension to adjust for a brake pad issue. If there is plenty of evidence that it's more than just brake pad, fine, go for it. But adjusting the suspension and saying "there, it's fixed" without any other testing or evidence seems pretty silly to me.


Jack, we have found basically the same thing you are saying in E36's also. Adjusting the suspension can help this situation but its not always a viable solution as some people are not running an adjustable setup. Also we found that most people like the extra stability added with the more aggressive pad in the front. It all comes with to driving style and driver comfort level / experience. I am not saying one way is faster than the other either, it will take some testing / tuning to see what works best for your overall setup.