Pelican Parts
Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   Pelican Parts Forums > Porsche Forums > 911 / 930 Turbo & Super Charging Forum


Reply
 
LinkBack Thread Tools Rate Thread
Author
Thread Post New Thread    Reply
Is very busy
 
TheRedSlantnose's Avatar
 
Join Date: Feb 2014
Location: Keller, TX
Posts: 485
Garage
Porsche Crest 930 stopping distance?

I often drive fast in my 930, and one of my constant concerns with doing so is having enough room in front of me to be able to brake efficiently. I know the 930 brakes were similar to the 917's, so I assume it has good stopping distance, but being "yesterday's technology", I have my doubts.

Does anyone know the 60-0 mph stopping distance of a 930? Extensive specs like this seem to be hard to find for 930's (I once tried searching for the drag coefficient of a 930 Slant, but found no info on it), so I don't really think it'd be easy to obtain that info here either.

__________________
Jason

1987 930 Slantnose Cabriolet, 545 hp, Guards Red- Weekend cruiser
1986 944 Turbo (951), 350+hp, Guards Red- Track car
2005 Toyota Tundra SR5 Double Cab 4x4, stock 282 hp, Silver- Daily driver
Old 10-21-2014, 05:54 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #1 (permalink)
Registered User
 
Ken911's Avatar
 
Join Date: May 2005
Location: Loxahatchee, florida
Posts: 2,745
Also anything published would probably be on stock tires. Newer larger tires like everyone is running would probably make the stopping distance much shorter than published.
__________________
88 turbo Guards red Targa slant nose, and yes I am a horsepower junkie, 3.4liter,7.5 to 1 JE pistons, Adjustable WUR, Imagine fuel head, 1 bar waste gate headers,allthe cis toys. Now apart to become the next EFI monster. fabbing my own intake, headers Individual throttle bodies, MS-3, pauter rods, Xtreme twin plugged heads, gt-2 evo cams cop's.
2019 Silverado 6.2L
Old 10-21-2014, 06:31 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #2 (permalink)
Registered User
 
dos531's Avatar
 
Join Date: Apr 2014
Location: Los Angeles
Posts: 758
Garage
Quote:
Originally Posted by TheRedSlantnose View Post
I often drive fast in my 930, and one of my constant concerns with doing so is having enough room in front of me to be able to brake efficiently. I know the 930 brakes were similar to the 917's, so I assume it has good stopping distance, but being "yesterday's technology", I have my doubts.

Does anyone know the 60-0 mph stopping distance of a 930? Extensive specs like this seem to be hard to find for 930's (I once tried searching for the drag coefficient of a 930 Slant, but found no info on it), so I don't really think it'd be easy to obtain that info here either.
The 930 can lock up the tires easily so there's no shortage of power. The lack of ABS is what is going to increase the stopping distances. Learning how to threshold brake is a must to drive these cars fast. With modern tires it will stop pretty damn quick.
__________________
'86 930 Guards Red - EFI MS3Pro, 80lb inj, 3.4, GT35R, Tial 46, Bosch 044, B&B Headers, 3.2 carrera manifold, Turbokraft Full bay IC
'12 Gallardo LP-570-4 Performante
'01 996tt
Ducati 748R
Old 10-21-2014, 06:48 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #3 (permalink)
Registered User
 
Oh Haha's Avatar
 
Join Date: Oct 2003
Location: Michigan
Posts: 14,095
Per Car and Driver review of a 1986 930> 60 to 0 = 173 ft
__________________
1981 911SC ROW SOLD - JULY 2015
Pacific Blue

Wayne
Old 10-21-2014, 07:01 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #4 (permalink)
Registered User
 
Join Date: Mar 2011
Posts: 865
wow 170+ feet is really bad- I would love to see a now days test. I was wondering this on my track prepped sc the other day... maybe ill do some tests/
Old 10-21-2014, 07:33 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #5 (permalink)
Registered User
 
clutch-monkey's Avatar
 
Join Date: Nov 2010
Location: Brisbane
Posts: 915
yeah i wonder how much of that is 1980's tyre.
Old 10-21-2014, 07:49 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #6 (permalink)
 
Registered User
 
dos531's Avatar
 
Join Date: Apr 2014
Location: Los Angeles
Posts: 758
Garage
Quote:
Originally Posted by clutch-monkey View Post
yeah i wonder how much of that is 1980's tyre.
I'd say probably most of it. The 930 has pretty great brakes even compared to some modern cars, and its lightweight. I'm sure with modern tires the stopping distance would be MUCH shorter.
__________________
'86 930 Guards Red - EFI MS3Pro, 80lb inj, 3.4, GT35R, Tial 46, Bosch 044, B&B Headers, 3.2 carrera manifold, Turbokraft Full bay IC
'12 Gallardo LP-570-4 Performante
'01 996tt
Ducati 748R
Old 10-21-2014, 10:51 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #7 (permalink)
Registered User
 
Join Date: Jun 2010
Location: beaux arts, wa
Posts: 485
Garage
Plusses:

- You probably have stickier tires tires than most cars and trucks on the road (and certainly compard to when your car was built)

- the 911 has excellent weight distribution for braking- engine weight in the rear gives rear tires additional traction compared to front engined cars that immediately overweight the front tires.

Minuses

- No abs means you need to learn to keep all the wheels from locking - especially difficult in the rain or when also turning.

-old brake system may not modulate well

Forget the magazine reviews, they're old and invalid because the tires have changed hugely. Practice your emergency braking and you'll have a healthy respect for the distances that may be required. This is covered in driver skills classes.

917 based brakes resists brake fade for repeated stops so not really relevant to "best stopping distance". Every car can emergency brake once.
Old 10-22-2014, 05:49 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #8 (permalink)
Registered User
 
Join Date: Sep 2002
Location: Westchester County, NY
Posts: 1,976
Garage
Quote:
Originally Posted by zakthor View Post

917 based brakes resists brake fade for repeated stops so not really relevant to "best stopping distance". Every car can emergency brake once.
A point worth reiterating. Better brakes handle heat better for repeated stops. Better tires make for better stopping distances. Assuming very artful threshold braking, even 4 wheel manual drum brakes (as long as they can apply enough force to overcome the tires) will stop the car in the same distance as any other brake. Repeatedly is a different story. But these magazine 60MPH-0 tests are once. They are a function of the car's weight, it's weight transfer characteristics, and the tire choice.
__________________
Ken
1986 930, 1969 Mach1, 2003 540 Sport, 2016 R1200RS
Old 10-22-2014, 08:18 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #9 (permalink)
Registered User
 
mussberger's Avatar
 
Join Date: Apr 2003
Location: new jersey
Posts: 224
I had these brakes along with the corresponding master cylinder on my E class 911sc. Granted top track speed was never above 125 but every one that drove it including me were amazed at how much feel they gave you. I never had any problems with lock up. R comps.
__________________
1981 911SC Black metallic, no sunroof. Sold(damnit)2005 987Guards Red, Stuttgart build. Sold1978 911SC Bahama Blue, M491 look E class PCA race car.Sold with help from Pelican. Thanks! 2005 997 Black. Sold1988 930 Grand Prix White. Keeper. 2008 957 Basalt Black, Pneumatic suspension and PDCC.
Old 10-22-2014, 09:34 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #10 (permalink)
Registered User
 
Join Date: Jul 2003
Location: Back in B'ham, AL
Posts: 3,450
I'm not sure of the exact answer - but 170' appears to me totally outdated - but can tell you that if you learn to "modulate" the 930 brakes you don't have to even think/worry about braking distance. Lock ups, as always, is a reaction of overspeed to the conditions...

Last edited by Miguel Antonett; 10-23-2014 at 10:54 AM..
Old 10-23-2014, 10:00 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #11 (permalink)
Registered User
 
T77911S's Avatar
 
Join Date: Oct 2006
Location: MYR S.C.
Posts: 13,586
Quote:
Originally Posted by TheRedSlantnose View Post
, so I assume it has good stopping distance, but being "yesterday's technology", I have my doubts.

.
yesterdays technology has nothing to do with it. the 930 brakes are still great brakes.

here is waht makes the difference:
tires
brake pads
condition of the system
the foot applying the brakes

what scares me about mine is the PO put on cheap mentex pads. 3 or 4 stops from 100+ and they are gone. so if i hit the brakes once or twice i have to just slow down because i dont know if i will have brakes the next time.
they really feel like they glaze over.

my 77s stopped better than my 930. if i did not have my seat belt on i would slide forward out of the seat. they were also much quicker to grab. again, cheap pads on the 930.
__________________
86 930 42kmiles [__] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD
88 BMW 325is 200K+ SOLD
05 BMW 330CI 130K:: [__] RUNNING: [__] NOT RUNNING:
08 VOLVO V70 190K:: [__] RUNNING: [__] NOT RUNNING:
90 B2200[__] RUNNING:[] NOT RUNNING:__2000 MER E320 WAGON [] WRECKED:[]RUNNING:
Old 10-23-2014, 10:37 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #12 (permalink)
Registered User
 
Join Date: Jul 2003
Location: Back in B'ham, AL
Posts: 3,450
^^^ how about changing the pads?
Old 10-23-2014, 10:55 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #13 (permalink)
Registered User
 
Tug68's Avatar
 
Join Date: Sep 2008
Location: Rockland Co.New York
Posts: 801
+1👆
Old 10-23-2014, 11:10 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #14 (permalink)
Registered User
 
mussberger's Avatar
 
Join Date: Apr 2003
Location: new jersey
Posts: 224
Best pads in the world can be humped without proper bedding in.
__________________
1981 911SC Black metallic, no sunroof. Sold(damnit)2005 987Guards Red, Stuttgart build. Sold1978 911SC Bahama Blue, M491 look E class PCA race car.Sold with help from Pelican. Thanks! 2005 997 Black. Sold1988 930 Grand Prix White. Keeper. 2008 957 Basalt Black, Pneumatic suspension and PDCC.
Old 10-24-2014, 03:32 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #15 (permalink)
Crotchety Old Bastard
 
RarlyL8's Avatar
 
Join Date: Jan 2000
Location: Huntsville, AL
Posts: 14,123
Garage
One thing to consider with the slant is the section width limitations for the front tires. My frog eyed fender Red Rocket ran 255 or 265 mm tires on front that would throw you through the windshield before locking up. The slant has 245mm and I notice a difference. I started out with 225mm which I considered dangerous and immediately removed.
__________________
RarlyL8 Motorsports / M&K Exhaust - 911/930 Exhaust Systems, Turbos, TiAL, CIS Mods/Rebuilds
'78 911SC Widebody, 930 engine, 915 Tranny, K27, SC Cams, RL8 Headers & GT3 Muffler. 350whp @ 0.75bar
Brian B. (256)536-9977 Service@MKExhaust Brian@RarlyL8
Old 10-24-2014, 03:46 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #16 (permalink)
Registered User
 
IMR-Merlin's Avatar
 
Join Date: Oct 2010
Location: Southern NH
Posts: 3,687
Another thing to consider is alignment. Whats best for cornering is not always best for braking. I suggest as others have in this thread to practice some threshold braking to get a feel for your car. Learn to modulate the pedal to avoid lock up. Even with the new cars, some good drivers can get better 100-0 distances with the ABS turned off vs mashing the pedal to the floor with ABS. The harder you push the pedal in a panic situation with ABS, the longer it takes to "reset". Now with the faster processing speeds, it's much better, but the early ABS cars weren't great for track cars.
Old 10-24-2014, 04:14 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #17 (permalink)
Registered User
 
gumba's Avatar
 
Join Date: Dec 2001
Posts: 4,166
On our race car I found the fronts to lock up due to the tire size difference, Hoosier r6 255 fronts & 315 rears. One compensation you can make is to use a more aggressive rear pad vs the front. Or, and more costly is to add a dual m/c setup.
My first suggestion would be to go do at least a couple of PCA D.E.s so you get a feel of how the car handles under braking at high speeds.
Or, find a long straight 4 lane road with little traffic and try some high speed panic stops to see if & what locks up, does it track straight etc.
In a panic stop most folks don't have the presence of mind to modulate the braking based on what the car is doing.
__________________
Harold
'79 930/DP935
'68 VW 3.3 Turbo Crewcab
Old 10-24-2014, 07:35 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #18 (permalink)
 
Registered User
 
Join Date: Jun 2010
Location: beaux arts, wa
Posts: 485
Garage
Some other effects that were more significant than I expected:

- I can't just slam on the brakes, important to apply the pressure gradually (reach full pressure over 1/4-1/2 second). If I apply pressure too quickly I'll shock the front suspension and tires and the front wheels will lock. If locked fronts you need to back way off to regain traction. This has to do with weight transfer to the front wheels.

- Turning has a big effect on braking: if you're near the limit and turn the inside front wheel will lock. If you're braking and need to turn (like - to avoid something) you need to back off the brake in order to maintain traction. I found this pretty difficult in the dry where braking works so well, the sign for me was that steering didn't work so well with a wheel locked. In the rain and wet I found it easier since the difference in traction between rolling and skidding tire is so much more obvious. I found peak traction was surprisingly difficult to maintain.

- I was able to lock all 4 tires individually, based on varying weight transfer. Was much more difficult to detect when rear tires were locking. This matters: the wheels need to be rolling to achieve max traction.

Spending time to practice and explore threshold braking and maneuvering has made me a much more conservative driver and I've much more respect for modern cars with abs. Would be really embarrassing to plow into the rear end of a camry because you were out-braked.
Old 10-24-2014, 08:28 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #19 (permalink)
Chain fence eating turbo
 
Join Date: Dec 2008
Location: Austin, TX
Posts: 8,844
All these theories with no numbers. I know how to get there too as 911's don't like stomping the brakes until weight has transferred to the front.

Anyone with hard numbers?

__________________
Cory - turbo'd '87 C3.2 Guards/Blk, 3.4, 7.5:1 CR P & C's, soon to be 993SS cams and GSXR 750 ITB's fed by 964 intake, Borg-Warner S366 turbo @ 1.4 bar, Treadstone full bay IC, TiAL F46 WG, HKS 1 1/2" BOV, twin 044 pumps, MegaSquirt 2 (v3.57 board) w/EDIS, Tramont wheels (285's rr, 225's frt), Big Reds frt, 993 rr., tower brace, MOMO wheel
Old 10-24-2014, 11:25 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #20 (permalink)
Reply

Thread Tools
Rate This Thread
Rate This Thread:

 


All times are GMT -8. The time now is 04:59 AM.


 
Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2020 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page
 

DTO Garage Plus vBulletin Plugins by Drive Thru Online, Inc.