What does your car feel like braking hard from 100mph?

[echrisconnor]

I'm curious what people's braking experieces are when braking from speed.

Part of the reason I ask may be in diagnosing a problem in my car. The thing is I don't know if it's a problem, or just the way my car is.

When braking hard from 60 mph, I could take my hands off the wheel and stop in a straight line. From 100mph though, the car is very darty. It doesn't pull to one side, it just seems to need lots of correction in both directions. I don't feel as confident really laying on the binders from this speed. Maybe it is just a non-power steering car that I'm not used to.

The car has been corner balanced, front calipers rebuilt. All soft brake lines replaced with SS lines and properly bled. I had have it aligned to BA's recommended Street/track settings.

[Dantilla]

When I had a 944 turbo, braking from 100 would pop my eyeballs out, and bounce them off the windshield.

[ttweed]

I think what you're feeling is the effect of aero forces coming into play at 100 vs. 60 mph. The car is essentially "lighter" from the aerodynamic lift on the chassis, and under hard braking from 100, with the associated forward shift in forces on the suspension, the aero lift in the rear is leaving even less grip for the rear wheels, essentially increasing your rear brake bias, making the rears come closer to lockup and sketchy handling, perhaps?

Just my guess, as everything in your brake system seems to be in good order otherwise, although you haven't rebuilt the rears, according to your description. You definitely need to be smoother on the brakes at that speed. Any slight turning force is amplified with so little grip in the rear. Do you have a rear spoiler?

TT

[banjomike]

I have neither power steering nor power brakes, and from 100 it stops like the hand of God is at work.

[echrisconnor]

No rear spoiler, but I do have a front valence (which may compound the problem). Will a rear spoiler make that much of a difference in braking? I also notice the car feeling twitchy when braking in anything other than a straight line (which I know I shouldn't do - just an observation).

[Slider79SC]

You didn't mention anything about any other suspension mods. Do you have any? These can also come into play?

Does it stop feeling twitchy after you reach a certain braking speed. For example, braking from 100 does it stop twitching at 60, 50, 40?

[JeremyD]

Mine feels like someone threw an anchor out the window...

[masraum]

Front lip without the rear spoiler could be causing the problem. Adding a rear spoiler would help at that speed initially until you got slowed down. Your car would look good with either a Ducktail or an early Carrera/turbo tail.

[Jbabic]

I was at Mid Ohio a few weeks ago...at 120 down the back stretch to a 90 deg right turn....felt great....just had to keep on the gas into the turn. I have a 930 wide body...so the front and rear spoilers come into effect....no pulling just a tight arse every time.

[echrisconnor]

No other significant suspension mods. Just a buch of little things: The rear trailing arm bushings have been replaced (Neatrix), turbo tie rods, many new sway bar busings. It has been lowered slightly (not slammed), bump steer kit. Bilstein shocks of undetermined age but the car doesn't bounce at all.

In general, the car feels darty at speed. When braking, I think it feels like the back end pushing around. Not sure though. Nothing locks up, but just needing little corrections when going fast is a little un-nerving.

[masraum]

Another thought. If those Bilsteins are old that could be the problem. My car didn't bounce at all and had what felt like a very firm suspension, but I figured it was time to replace them anyway. The old shocks/struts were totally shot. The difference was alarming, and now my car feels much much more stable at speed than it did before.

[Slider79SC]

I noticed you are from CO. Who did your corner weight and alignment? Our car was feeling kind on darty and we had the alignment redone and now it is MUCH better.

Did you have your car lowered and if so did they take the big ol' washer off of the top of the strut? This can also cause handling problems if it is not removed when the car is lowered.

Also, what size tires are you running? I have noticed that ours seems more darty with our larger street wheels and tires on.

[Early_S_Man]

Dead straight, stable, and just like a battleship anchor got dropped off the tail ... even from 125 mph one night in 1978 with skinny OEM 185/70VR-15's ... when three deer were standing across a narrow two-lane TX route 71 with no shoulders and 150 -200 ft drop-offs on both sides! Got stopped with 15 ft to spare thanks to the early warning from my 100 Watt H1's ... smelled that toasted-phenolic aroma for the next two hours, though!!!

[ChrisBennet]

Mine stops straight now but years ago the back end used to dance around under heavy braking. I got so used to it that I didn't even realize I was correcting for it. I just figured that was part of the "track experience" until an instructor rode with me and told me "No Chris, they don't all do that." Once I got it aligned it was fine. (Rear toe out is evil.)
-Chris

[Rick Lee]

Never tried to stop at that speed. When I do 100mph, it's usually on the way to 120 or 140.

[BGCarrera32]

Its pretty wild in mine because my seat belts suck, and I have the back 2 screws on the drivers seat taken out at the moment. I imagine I'd develop an even closer relationship with my steering wheel if I stopped like that...

[APKhaos]

There is something causing your instability under braking.
I have an 85 with front lip spoiler and no tail. 100% threshold braking from 130+ is no problem, unless I overbrake into lockup. Having flatspotted a few tires, I try to avoid that these days.

Alignment would be my first guess. Have the front AND rear checked. Shockes are possible, but check alignment first.

Mine was completely stable. Then I had the brakes "rustproofed" with oil (idiot workshop) which was later cleaned off. Even if it's ok now it's still not as good as before the "rustproofing". Recently I braked pretty hard from about 125 mph. Braking power is strong enough, but unfortunately slightly out of balance. The car pulled to the left.

[rdane]

Hard braking from 100? Better make sure the passengers are prepared
930 brakes on an SC and it is impressive....I laugh with the hands removed and watch the little bit of shimmy in the steering wheel as I stand on them to zero in a straight line and in an amazing hurry.

[echrisconnor]

I don't see anything that should cause the unstability. Maybe it's my shocks. Maybe the alignment, although it was done recently. It's possible that my brake pads are contaminated with something after all the work has been done - but I don't know. Where would you start looking?

Can you have alignment re-checked? Or do you just have it done? I'd hate to shell out another $100 if I don't have to, but whatever the issue is I'd feel better having it sorted out.