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I've noticed that when cornering and braking the *** end likes to get really light quick and it feels like it wants to step out. Anyone else experience this? It's pretty unnerving and I'm worried that I might loop it out one day.
I get that on uneven or bumpy pavement when cornering, don't let there be any lose dirt or gravel. Once it gets on even pavement. it stick like glue...
Yes, this will happen and has happened to me on track and on the street. The general rule here is when in doubt throttle out. off the brakes and on the gas. Weight should transfer to the back of the car and settle the rear end. Careful to put too much throttle or you will to go into understeer which is worse than overstreer; as you see the tree that kills you.
From: Portland, OR *currently in a temporary email address
Engineering types, please correct me on my terminology, but here's the oversimplified way that I picture it in my head:
Tires can only hold a certain amount of G's in any direction. Think of it like a "circle of grip". Maximum acceleration is achieved in a straight line, where the forces on the tires are parallel to the body of the car.
As soon as you add steering, you're adding a lateral force to the mix.
If you're going the same speed forward into the corner as you were in the straight, and you turn with the force shown above, your resultant force is like so:
...which is outside of the "circle of grip."
The key then, is to decelerate just enough before entering the corner for your tires to be able to hold the additional lateral force of the turn.
It's not a perfect formula, because it doesn't account for road surface, difference in tire pressure between your wheels, worn suspension parts, etc, but the idea is there--keep your fore/aft acceleration to a maximum in the straights, and decelerate before the turn to keep yourself within the happy circle shown below.
Rainy parking lots are your friend, so are soft dirt roads. Get practice intentionally losing traction as much as you can in a low-speed, safe environment, so that when you're hauling *** in the mountains, you're not giving yourself any close calls. Worst case, you a take a turn too slow, you can always turn a little more aggressively next time! Also, keep in mind that your front tires will grip more while turning on an incline, and less, when turning in downhill. This can make for some sketchy, or fun, situations, depending on your comfort level. Practice makes perfect, and when the risk is a beautiful MINI and potentially a beautiful life, it's always best to be conservative and slowly up the ante as you get more comfortable.
tldr; Try braking in the straight before the corner to an appropriate entry speed, and shift to light pressure on the accelerator just after you turn in. Find the balance of just enough throttle to keep the car out of understeer until you pass the sharpest point of the corner, then roll into throttle on exit! Happy motoring!!!!
Yep if you get good weight transfer the rear will get light. This is important in autocross & on the track when trail braking to get the rear end to rotate
if you have adjustable shocks you can increase front damping on compression, and you can increase rebound damping on the rear but it comes at a price it will probably reduce your corner speed on the track, where you want as much weight transfer as you can get so the front wheels grip
In this case (reducing oversteer), make the front tire pressure lower than the rears. Also, higher performance tires will give you better overall grip.
All basic driving instructors will tell you to get your braking done before cornering. It's one thing to do alittle trail-braking while cornering but you shouldn't be full one braking while turning the steering wheel.. and as someone mentioned above when in doubt gas it..
I've noticed that when cornering and braking the *** end likes to get really light quick and it feels like it wants to step out. Anyone else experience this? It's pretty unnerving and I'm worried that I might loop it out one day.
I fought this problem for quite a while (since the car was new), especially going into turn 1 at Watkins Glen, which is downhill and makes the back really light when I hit the brakes. It would also do it going into T1 at Lime Rock.
The solution was surprised and came from an E30 racer/instructor. He told me to put more braking in the rear. Yes, more in the rear. What I was told was that this will "help to hold the rear down". I have Wilwoods with the 11.75 in. rotors in front and stock S brakes in the rear. I am running Hawk DTC60 pads both front and rear, which is quite aggressive in the rear, but it works. What also helped me is 1 psi less pressure in the rear tires as compared to the front. With this setup that tail wiggle is gone. And I can trail brake a long ways into a corner if I need/want to.
What size rotors are you running with the Wilwoods?
I am not a fan of street/track pads for the track. The HP+ have a fairly low max temp rating. I ran the Hawk Blues, which have more grip and a high max temp, and ran out of range on them and still had the wiggle. I matched the blues with both the Wilwood Poly H and DTC-60s up front. Unfortunately, I expect you will have similar results with the HP+ as I did with the blues.
On another note, I just read the Wilwood notes about the BP40 pads. Those sound interesting, but I couldn't find any temp ratings on them.
I used hp+ in rear with dtc60 or gloc 12 up front all year, the hp+ is the highest torque pad I could find that does not have to be hot to work I can't get my rear brakes hot
I wish there was a way to adjust brake bias I'm having to do it with pad choice
I have the 11 something wilwoods, should stop the same as my jcw fronts did but with better cooling capacity. I hope I do not miss the simplicity of single piston calipers
sway bar makes no difference in the rear getting light when braking straight, only when cornering and then it's just transmitting torque across the rear
I've noticed that when cornering and braking the *** end likes to get really light quick and it feels like it wants to step out. Anyone else experience this? It's pretty unnerving and I'm worried that I might loop it out one day.
There are so many missing pieces of information:
do you have stock rear sway bar, if not what size, and what is the setting if adjustable
tire pressure front and back
is the corners in question smooth, bumpy, undulating?
is this dry or wet pavement?
driver preference and habbit
I remember you have stock springs and dampers. Most cars are set up to be heavily understeer-bias from the factory.
I fought this problem for quite a while (since the car was new), especially going into turn 1 at Watkins Glen, which is downhill and makes the back really light when I hit the brakes. It would also do it going into T1 at Lime Rock.
The solution was surprised and came from an E30 racer/instructor. He told me to put more braking in the rear. Yes, more in the rear. What I was told was that this will "help to hold the rear down". I have Wilwoods with the 11.75 in. rotors in front and stock S brakes in the rear. I am running Hawk DTC60 pads both front and rear, which is quite aggressive in the rear, but it works. What also helped me is 1 psi less pressure in the rear tires as compared to the front. With this setup that tail wiggle is gone. And I can trail brake a long ways into a corner if I need/want to.
I think this is the closest match to my issue - it really started after I redid the front brakes with PowerStop rotors, SS lines, and Street Performance Pads. Everything in the rear is stock and the suspension is completely stock otherwise. This also includes (for now) the worn control arm bushings and god knows what else is worn out. I just got the car - it has 67k miles. I do have the Sport Plus suspension though. I'm running 30 PSI in the crappy Fuzion tires the car came with.
...there's a lot of stuff going on there that could be a contributing factor.
Thinking physics wise, and knowing that Nascar has rear brake controls, more braking force in the rear would compensate for the front end diving down during hard braking.
The simplest and cheapest fix is to get all your braking done in a straight line - before the turn. No trail braking which it sounds like what you are doing. No Lift off overstreer either - though overstreer is better as you don't see the tree that kills you. Add power, at an even pace, at or just before the apex to power out of the turn - this will transfer weight to the rear wheels - giving them more grip and settling the rear of the car. Our Gen1 cars have the EBD - electronic brake distribution - so it should be able - to some very minor degree (if any) - bias front/rear as needed even in a turn. If you have the DSC, this could possibly "amplify" the EBD's ability a little bit. Physics is your best friend and biggest enemy when in a corner.
Thinking physics wise, and knowing that Nascar has rear brake controls, more braking force in the rear would compensate for the front end diving down during hard braking.
The ABS module would have to modified, correct?
Originally Posted by mega72
Yeah with coding, there is a race version but it's rare and afaik only setup for bmw & porsche
A simple bias valve would be nice but these new abs systems don't work like that all we can do is play with pad choice
The r56 has a jcw code change, not sure what it does
I have that JCW coding. It is for the installation of the Brembo style JCW brakes and matching those to the ABS unit. This mostly helps with the eLSD.
Way too complicated to put in biasing units on a stock street car.
Originally Posted by RedAggie03
I think this is the closest match to my issue - it really started after I redid the front brakes with PowerStop rotors, SS lines, and Street Performance Pads. Everything in the rear is stock and the suspension is completely stock otherwise. This also includes (for now) the worn control arm bushings and god knows what else is worn out. I just got the car - it has 67k miles. I do have the Sport Plus suspension though. I'm running 30 PSI in the crappy Fuzion tires the car came with.
...there's a lot of stuff going on there that could be a contributing factor.
RedAggie03 - you made one change (redid the front brakes) and the problem started. Those other things were not changed, so whatever they were doing before they are still doing now and may have nothing to do with your problem. Start with the one change that you made. What you did is upgrade the fronts without upgrading the rear brake to match the front. The car probably had pretty well match brakes front and rear before you upgraded the fronts. So now, upgrade the rears to once again match the fronts. Make one change at a time and see how it affects things.
Originally Posted by Thought of a good one
The simplest and cheapest fix is to get all your braking done in a straight line - before the turn. No trail braking which it sounds like what you are doing. No Lift off overstreer either - though overstreer is better as you don't see the tree that kills you. Add power, at an even pace, at or just before the apex to power out of the turn - this will transfer weight to the rear wheels - giving them more grip and settling the rear of the car. Our Gen1 cars have the EBD - electronic brake distribution - so it should be able - to some very minor degree (if any) - bias front/rear as needed even in a turn. If you have the DSC, this could possibly "amplify" the EBD's ability a little bit. Physics is your best friend and biggest enemy when in a corner.
Only doing only straight line braking may help with that problem and surely is cheap, but it didn't help for me. With straight line braking my car would twitch from side to side if I was hard on the brakes. If I was early and lighter with braking I wouldn't have the problem but I would be getting off the gas early to do that and loosing time. Straight line braking also means that you are either coasting or, worse yet, on the gas on your way to the apex. If you are on the gas, the front is going to be light, you are going to loose camber and the car is going to push like crazy. Trail braking is a good thing to learn for a MINI as it allows you to carry more speed into a corner.
Back to what I said before, easiest fix is more aggressive pads in the back that better match the front. I heard what mega72 said about not getting enough heat into the pads (sorry I forgot that from before). I have had no problem getting heat into the rears (I have burned the paint of my DTC 60s). Not sure what is different as we have basically the same rear brakes. At this point, trying a more aggressive pad in the pad won't hurt and if works, it is a moderately cheap, easy fix.
The other option is to put in the R56 JCW rear brakes which have a larger rotor than stock. The larger rotor adds mass and increases torque which will effectively be the same as a more aggressive pad, but without heat issues. But this is expensive and may be too much brake in the back as it is supposed to be matched to the JCW Brembo style brakes with the 12.2" rotor.
10-18-2017 | 08:16 AM
