my driving and suspension tuning

[T77911S]

I tracked the 930 once last year, first time, and I tracked my BMW 330ci twice this year. both cars have stock suspensions.
the mistake I made in the 930 was I didn't try to run consistent laps. that is I short shifted at times, didn't floor it one the straights. part of this was due to brake fade. when I did drive fast my brakes were fading so I had to slow and I just worked in my line and learning the car.

with the 930 the back end would brake lose at turn in. so it was turn and right back on the gas to get weight on the rear. I never really had much under steer except maybe once or twice in the middle of turns due to too much gas. I did spend quite a bit of time sideways in the 930, mainly intentional so I could learn the limit of the car.

the BMW.
at first I had a lot of under steer. then started learning the car and my braking points and unlike the 930, I was more consistent at how I drove it. that is shifting at the same points, braking same points. (working up to my latest braking point).
I was able to get into a rhythm in the BMW
once I started getting the weight on the front the under steer went away then came the over steer at turn in.

second track with bmw
I got into a rhythm pretty quick. same thing. late hard braking with a lot of weight on the front, over steer at turn in.

so my question
am I driving the cars wrong. too much braking putting too much weight on the front
causing turn in over steer. did my driving compensate for the "factory" under steer

930 question
21/29 or 22/30 T bars have been suggested.
that ratio looks like it would "increase" my over steer.

I do want to track the 930 again now that my "initial shock" of my first track day is over so I can get a better feel for the stock handling before making changes


my brother did tell me that the people watching loved it when I came by. my tires were squealing under braking and going through the chicane.

[T77911S]

You can see i have a lot of weight on that right front

[Driven97]

The BMW is a traditional 50:50, front engine, rear drive experience. Car is inherently balanced, you tweak weight transfer timing to make little changes in said balance.

911s are just weird. The heavy part (engine) wants to be in the front, so it's inherently unstable. Lack of weight in front gives little authority to the front tires. So the rear stays planted and the cars push until the rears lose grip, then the car becomes like trying to balance a broomstick in your palm. Adding some throttle plants the rear and lifts the front, stabilizing the car, unless you add too much throttle to attain power oversteer and go back to the broomstick balancing again. The bandwith range between terminal understeer and difficult to manage oversteer is small. The super short wheelbase of air cooled cars makes things even more difficult.

On the other hand, the wacky weight balance allows for huge advantages in braking and corner exit traction that a front engine car could only dream of.

Mastering a 911 requires mastering timing of weight transfer, a deft feel for the limit, and a willingness to play at rear slip angles that are a bit puckering. This challenge is unique to the rear engine format and is an essential part of why the 911 is so loved.

I have a hard enough time keeping my NA 3.2 pointed straight. Add in boost lag and enough horsies to create power oversteer and I'd be in the weeds. Good luck and have fun, it's a very, very exclusive club to be one who can manage a 930 gracefully at the limit.

Corner entry oversteer is standard practice on a 911. Not impossible with the BMW. Most likely based on the timing of your braking and wheel input. Bombing into a corner hot and still on the brakes at turn in is called trail braking, and is a textbook understeer reduction technique. Keeps weight shifting forward, which puts grip on the front end and reduces grip on the rear end.

[911tracker85]

I do want to track the 930 again

cant wait until my 930 project is done, an SC/930 conversion. since not stock I am upgrading the suspension and brakes beyond what the build PO did.

I had an 85 911 I tracked for a few years, sold last year. slowly got used to and began to understand and 'master' its handling characteristics. of course with a LOT of help from DE instructors. now driving a modified 951. when I first built it, did the drive train but not suspension. on track immediately realized how much I needed a better suspension. under hard braking way too much load transfer to the front, would get real loose. did a full suspension upgrade and now the car feels planted.

what year is your 930? brake fade? what pads?

just got my modified rear 930 calipers done. having to grind off the little ears on the SC banana arms a bit to fit.

[T77911S]

I was just in KY at NCM,
great track. lots of fun.
I cant wait to run the 930 there although I think the 930 will be a hand full on that track. will have to drive it much differently than the BMW. at least I had time to learn the track in the BMW and not have to deal with the 930 too.

funny about the brakes
I have had issues with the 930 brakes since I bought it.
I noticed if I did a few hi speed (100mph) hard stops the brakes faded.
so I rebuilt the entire system minus a new MC. put in motul 600.
originally it had those cheap mentex pads so I thought that may have been it.
so I had cool carbons on at the track.
the pedal was not quite what it was before. so I used a power bleeder when I got back and the pedal is better. don't know if that effected the brake fade.
now I PFC pads on there but have not tracked it.

a little unnerving entering turns and not sure if you will have the brakes.
I almost ran off the end of the straight when I pushed the braking point a little more. good thing the turn was very wide.

[911tracker85]

sounds like the pads....

I eventually found Pagid yellow worked very well for me, on track and the street. tried the pagid orange, but they have very little stopping power when cold and need to be in the right temp range work to work well on the track.

good luck sorting this out.

[racer]

930s are a handfull thats what makes them fun!

You need to find an instructor familiar with a 930 and have them help you. 911's in general are different. You have to learn to steer by throttle and remind yourself not to lift, especially once your friend "boost" arrives 911's do well with the "slow in - fast out" cornering approach. In addition, driving a car without ABS might also be a challenge for your. Could be that in the BMW you don't realize how much you trail brake. Trail braking a 911 w/o abs will feel very different. Also, consider your 930 suspension was designed in the 1970s.. the BMW is much newer (better) in this regard.

930 brake fade? hmm.. High temp fluid? track pads? after that, add "air" or remind yourself that "brakes just slow you down" and learn to brake less

[patkeefe]

A stock 930 should not have any brake fade. Fade is from lack of heat rejection at the rotors. You probably have big rotors on that 930 from the factory.

A BMW handles like a BMW, which is totally different from a 930.

I only have a 911 with a turbo, so it is likely a bit different than a 930. But, an older 911 or a 930 are both sort of unique and stone-age compared to the BMW. My feeling is a stock 930 will kick a stock 325i all over the track.

If you run them both at the track, you will naturally think the 930 handles badly, compared to the BMW. Stay out of the BMW for a season, and report back.

[RSTarga]

I've owned two turbos and never experienced brake fade. They definitely require a different driving style. Braking late and turning in will provoke understeer. As mentioned above, you want to brake a bit earlier and make sure you are getting boost as you approach the apex. Get used to how and when comes in, smoothness is paramount.
I second Pagid pads and be careful how you bed them in.

[Cajundaddy]

The first step is to make certain that you have good tires, good brakes, and fresh brake fluid. It's hard to learn anything if you don't trust the car. I would also get an alignment and corner balance done to eliminate any glaring issues. Now the car is ready.

Step 2 is to get an experienced instructor in the car to work on smooth corner entry, getting the car completely settled so you can go to the throttle early.

Good luck!

[jpnovak]

Lots of great information here.

The 930 brakes should not have any fade. Period. If you have fade then you have something wrong with your system or you are braking completely wrong. System issues could be pad compound, rotor glazing, poor quality fluid, air in the system, etc. It could also be old brake lines that prevent the pads from retracting on the rotors. Braking problems include too much braking for too long of a time.

As other's have said, The trick to the 911/930 is balance. You need to learn the following process so that it is seamless and quick. Use the car to your advantage. Think of your cornering process like this:

-full throttle toward a corner.
-brake in a straight line before a corner.
-You should come off the brakes right at your turn-in point. Trail braking is difficult in a 911 but not impossible.
-The car will be front loaded when you come off the brakes and start turn-in. The front will have a lot of bite (traction). This is where maximum steering input has started.
-The next phase of the corner the car is turning. there are 2 weight transfers happening right now. 1) the car is coming off its Front weight bias and shifting to the rear. 2) the weight transfer is to the outside of the corner since you are now turning. If you are still braking the inside tire will try to lock-up as you unweight it.
-during the transition phase you will likely be off the throttle and the car will go through a F/R neutral stage while still having outside weight transfer. This is where things get tricky.
-At this point the weight will want to swing from the forward momentum to a side momentum so you need to maximize rear traction. How do you maximize rear traction in a 911? put your foot on the gas.
-Now you have applied throttle to balance your lateral weight transfer and turn some of this into forward momentum. The car at this point should "set" in a slightly oversteer position. This is good. This means you are going fast. You are now balancing the slide, push and traction with your right foot. Don't think you are going to hit your apex, "breathe off the throttle" and watch/feel the nose tuck in. Think you are sliding the rear too much, "breathe on the throttle" and feel the rear settle down and hookup more. You just have to be careful that with the turbo you are not going in/out of boost during these subtle transitions.
- once you pass the apex you are now unwinding the steering wheel (if you haven't already). The more you unwind, the more throttle you apply. Here is where the 911/930 really shine. They have amazing exit traction. Given enough power they have phenomenal exit speed. Basically you should be accelerating from before your apex.
- The rest is just hanging on and smiling getting ready for the next corner. which in a 930 should happen very quickly.


You need to have a good instructor that is familiar with a rear engine car help you out.
The entire process is basically one motion going through the corner. Smoothness is key in these cars. They are different than other well driving cars but quite rewarding when you get it right. and you will know when you get it right.

I recently sold my BMW e46 coupe. It was stupid easy to drive fast on the track. But I think my 911 is way more fun and will do things the BMW could never dream of. Yes, it trail brakes. You have figured this out by your picture. I can tell you are hard on the brakes turning left in that picture. I can also tell you that is not the fastest way to lap a BMW. try to brake earlier and let the car balance in a neutral position through the corner. It will be more stable and faster.

Additionally, The BMW never had the exit traction of the 911. Wheel spin post-apex and the car gets unsettled. But never felt unnerving.

Yes, I prefer the rear engine car.

[PeteKz]

I'll reemphasize what jpnovak wrote:
1. Get your braking done BEFORE turning in. Supposedly, you can carry a little trail braking into the turn, but I've timed myself and other people, and I can't tell that it helps lap times, whereas if you aren't real skilled at it, it will provoke a quick oversteer situation, which will scrub off speed (or worse!) and make you slower. So, focus on getting on your brakes hard and exactly at your brake marker, and be off them at the moment you turn in. Of course, if you are racing and in traffic, you will have to adjust for what other drivers are doing.
2. Set yourself up for the exit so you can get on the gas as early as possible. If that means going through the turn slower, make that tradeoff. If you come out of the turn faster, you will carry that additional speed down the next straight, which WILL reduce lap times.

[RSTarga]

Jamie's technique is well explained and spot on. I would only add that on the earlier Turbos throttle lag is substantial and if you lift you'll wallow around with no power. Try and learn how the boost comes in and work your way up to getting on the throttle progressively. It takes a lot of practice. Again smoothness is very important. I know everyone loves those videos of cars sliding on opposite lock, but this scrubs off speed and costs lap time.
Please do this on a track, on the road be way more conservative.

[T77911S]

Originally Posted by racer

930s are a handfull thats what makes them fun!

You need to find an instructor familiar with a 930 and have them help you. 911's in general are different. You have to learn to steer by throttle and remind yourself not to lift, especially once your friend "boost" arrives 911's do well with the "slow in - fast out" cornering approach. In addition, driving a car without ABS might also be a challenge for your. Could be that in the BMW you don't realize how much you trail brake. Trail braking a 911 w/o abs will feel very different. Also, consider your 930 suspension was designed in the 1970s.. the BMW is much newer (better) in this regard.

930 brake fade? hmm.. High temp fluid? track pads? after that, add "air" or remind yourself that "brakes just slow you down" and learn to brake less

oh I loved how I could steer with the throttle. lots of fun.
was trail braking the BMW. that's how I over came the under steer when I was going "slower" at first. later braking and harder braking with trail brake was making the back end brake loose on turn in.

I guess my real question was am I making up for handling problems with my driving or was I making it handle poorly with my driving. mainly, was I still too much on the brakes at turn in. I wouldn't want to make suspension changes to the 930, that is add more under steer, if I was driving it wrong.

[T77911S]

Originally Posted by jpnovak

Lots of great information here.

The 930 brakes should not have any fade. Period. If you have fade then you have something wrong with your system or you are braking completely wrong. System issues could be pad compound, rotor glazing, poor quality fluid, air in the system, etc. It could also be old brake lines that prevent the pads from retracting on the rotors. Braking problems include too much braking for too long of a time.

As other's have said, The trick to the 911/930 is balance. You need to learn the following process so that it is seamless and quick. Use the car to your advantage. Think of your cornering process like this:

-full throttle toward a corner.
-brake in a straight line before a corner.
-You should come off the brakes right at your turn-in point. Trail braking is difficult in a 911 but not impossible.
-The car will be front loaded when you come off the brakes and start turn-in. The front will have a lot of bite (traction). This is where maximum steering input has started.
-The next phase of the corner the car is turning. there are 2 weight transfers happening right now. 1) the car is coming off its Front weight bias and shifting to the rear. 2) the weight transfer is to the outside of the corner since you are now turning. If you are still braking the inside tire will try to lock-up as you unweight it.
-during the transition phase you will likely be off the throttle and the car will go through a F/R neutral stage while still having outside weight transfer. This is where things get tricky.
-At this point the weight will want to swing from the forward momentum to a side momentum so you need to maximize rear traction. How do you maximize rear traction in a 911? put your foot on the gas.
-Now you have applied throttle to balance your lateral weight transfer and turn some of this into forward momentum. The car at this point should "set" in a slightly oversteer position. This is good. This means you are going fast. You are now balancing the slide, push and traction with your right foot. Don't think you are going to hit your apex, "breathe off the throttle" and watch/feel the nose tuck in. Think you are sliding the rear too much, "breathe on the throttle" and feel the rear settle down and hookup more. You just have to be careful that with the turbo you are not going in/out of boost during these subtle transitions.
- once you pass the apex you are now unwinding the steering wheel (if you haven't already). The more you unwind, the more throttle you apply. Here is where the 911/930 really shine. They have amazing exit traction. Given enough power they have phenomenal exit speed. Basically you should be accelerating from before your apex.
- The rest is just hanging on and smiling getting ready for the next corner. which in a 930 should happen very quickly.


You need to have a good instructor that is familiar with a rear engine car help you out.
The entire process is basically one motion going through the corner. Smoothness is key in these cars. They are different than other well driving cars but quite rewarding when you get it right. and you will know when you get it right.

I recently sold my BMW e46 coupe. It was stupid easy to drive fast on the track. But I think my 911 is way more fun and will do things the BMW could never dream of. Yes, it trail brakes. You have figured this out by your picture. I can tell you are hard on the brakes turning left in that picture. I can also tell you that is not the fastest way to lap a BMW. try to brake earlier and let the car balance in a neutral position through the corner. It will be more stable and faster.

Additionally, The BMW never had the exit traction of the 911. Wheel spin post-apex and the car gets unsettled. But never felt unnerving.

Yes, I prefer the rear engine car.

that's exactly how I was driving, or at least trying. consistency was not there. (my fault). very quick back on the gas after turn in to control the rear.
I did "over dirve" it one session. wanted to learn the limit of the car....and me. there were a few times it was sideways so far I was resolved to "its going around this time". after that session the back end was still hanging out not as far.
most of the turns I was way off boost due to the 930 gearing.
so it was floor around the apex then roll off the gas as boost came in.
I have a 7006 turbo, boost is very late but hard.

my instructor did tell me he was very scared about getting in the car the first time because of its reputation. then he said I do know how to handle the car

yes, the BMW was much easier to drive. turn in response was much quicker than the 930.


I have had an issue with the 930 since the day I bought it.
I have different pads now, and the system is bled better so I hope its resolved.

starting engine rebuild soon

[racer]

What is your current suspension - ie, 35 year old rubber bushings? tie rods? shocks?.

even stock, a 930 will seem relatively soft by modern car standards. Also, by 1986, the lawyers at Porsche realized they needed to dial more understeer into the car, in an attempt to handle the snap throttle oversteer and kep their buyers alive .

Stiffening torsion bars will help limit body roll. They can also reduce the amount of understeer which I don't think is a bad thing. The more responsive, the less time wasted trying to understand whats going on as the vehicle transfers weight all over the place.

That said, I would learn to drive your "ill" handling car so that you can come to a decision on what you want to change. When I bought my SC in 2000, it had about 15 year old suspension on it. I spent a year learning how to be a yaw manager, non ABS manager, weight transfer manager etc. Eventually I got quite good at managing all that and then realized how much I was overdriving. That I needed to button the car down with some improvements. I would suggest the same to you.

And the summary to drive is:

Brake in a straight line.
Off brakes /Turn in
Aim for apex
Feed in throttle.
(learn to time boost arriving at Apex or slight later as you straighten the wheel)
Leave pesky Miata behind till the next corner

[RSTarga]

I always ran a tad of toe out at the front to reduce understeer.

[T77911S]

relatively low miles 930. got it with 40k now 70k.
suspension and bushing still pretty tight.
so if mid corner and exit are ok then just deal with the turn In the way I have been.

just making sure my driving wasn't promoting ill handling of the 930.
I assume the way I was driving the BMW was overcoming its short comings of under steer

not going to do anything to the 930 until I do get more track time.


Miata! that's funny. he was eating my lunch in the BMW, but he also had racing slicks on it.

[911tracker85]

lots of great explanations.

I second Pagid pads and be careful how you bed them in.

yep, but if you do they work great. depending on your braking technique you may experience some brake shake if the bedding starts to get 'smeared'. will feel like warped rotors. if so will have to sand/clean the rotors smooth again, then rebed the pagid pads. in my case I had an older set of metallic pads I would throw in and drive for a couple days to clean the rotors.

remind yourself that "brakes just slow you down" and learn to brake less

there is a braking technique used on the track that you DO NOT want to do on the street. as you approach the braking zone, go hard on the brakes as quickly and smoothly as you can and take it up to threshold. again ... smoothly ... dont stomp the brakes.

the idea is you get the most braking done when the brakes are at there 'coolest'. then as you approach the turn-in point 'breathe' off the brakes rather than a fast release. if you breathe off the brakes you let the weight transfer off the front to be smooth and not cause the front suspension to pop up and unsettle the car. and when doing this and getting comfortable with it and your car, it lets you brake later.

do you find yourself braking, then letting off and 'coasting' a little bit before turn-in? after years of DE it is still a bit of a challenge to fully exploit this. but then DE is not racing and no $$ involved, other than what it costs to fix the car after you stuff it into a wall.....

The rest is just hanging on and smiling getting ready for the next corner.

I recall reading an article about 911s before I got mine 30 yrs ago. dont recall the driver's name, but he was commenting he did not like to drive in the IROC when they used 911s. "if you go into a corner too fast you do not have the option of letting off the gas. just floor it and steer like a mad man..."

I would only add that on the earlier Turbos throttle lag is substantial and if you lift you'll wallow around with no power.

I have been dealing with Steve Weiner at Rennsport Systems for years. when I got my 930 project and we were discussing build ideas, he told me about when he had raced 935s. said you have to left foot brake a lot so you can keep on the gas and the turbos spooled up. and how the 935 fights you in the corners.

I always ran a tad of toe out at the front to reduce understeer.

yep, makes for fast turn-in but tends to make the car a bit twitchy. a little toe in on the rear. and the more neg camber will cause the car to want to wander back and forth on crowned pavement. kept expecting to be pulled over for drunk driving....