View Poll Results: If you track your 928, choose differential used:
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POLL for 928 Track Cars: Limited Slip or Open Diff?
POLL for 928 Track Cars: Limited Slip or Open Diff?
11-29-2008, 11:46 AM
#2
Race Director
limited slip................its a must have really...... in general the tighter and slower the course the more you need LSD to power out of corners.....otherwise you'll be spinning 1 tire all day
11-29-2008, 11:48 AM
#3
Race Car
Thread Starter
I spin a tire, but the trick for me is to over rotate the car so I can get back onto full throttle sooner. I also try to be extremely light in reapplying throttle so as to avoid spinning the inside tire.
Tire spinning is TONS worse on track tires than on street tires. I find it easier to drive open diff on street tires than on track tires.
Tire spinning is TONS worse on track tires than on street tires. I find it easier to drive open diff on street tires than on track tires.
11-29-2008, 08:31 PM
#6
Nordschleife Master
My S4 with 10k track miles on it has an open diff. Did not hold me back much...but that is probably a factor of the auto trans... With a 5spd you are going to be WAY more likely to spin the tires up. Only on the slower corners of the big open fast track I normally drive do I ever have issues with spinning the tires on my S4.
The race car has a '90 LSD and it is locked down fully. But with 219HP and 12" slicks there is not much worry of spinning those tires unless they are cold, then they are pretty easy to spin!
The race car has a '90 LSD and it is locked down fully. But with 219HP and 12" slicks there is not much worry of spinning those tires unless they are cold, then they are pretty easy to spin!
11-29-2008, 09:26 PM
#7
Rennlist Member
I raced in my early races with an open diff. It only was a problem at turn 11 at laguna , sears and turn 2 at sears as well. the more hp you have the more this can be a problem if you dont have a limited slip diff. my 79 track car with 200rwhp (approx) had one race under its belt with an open diff. 2:10 at thunderhil and turn 5 and 10 were a little tough to get the power down. scot raced with one for a long time, and when he got the LSD the main thing he noticed was how easy the trail brake turns became with the use of engine braking
mk
mk
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11-30-2008, 03:33 AM
#9
Addict
Rennlist Member
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LSD on mine (w/ more than stock lock %)
When I first bought my track car, it didn't have one. Open diff + stiff suspension meant lots of one-wheel spin. One of the first mods I made was the addition of a LSD. I've driven open diff cars since then and it's noticeably slower. I'd recommend a LSD. You won't go back to an open diff.
When I first bought my track car, it didn't have one. Open diff + stiff suspension meant lots of one-wheel spin. One of the first mods I made was the addition of a LSD. I've driven open diff cars since then and it's noticeably slower. I'd recommend a LSD. You won't go back to an open diff.
11-30-2008, 07:30 AM
#10
Rennlist Member
On the subject of LSDs does anyone have experience of using a "Phantomgrip" LSD
in a 928 or in any other car for that matter. (www.phantomgrip.com)
They seem to be well regarded in motorsport circles and are not too expensive.
in a 928 or in any other car for that matter. (www.phantomgrip.com)
They seem to be well regarded in motorsport circles and are not too expensive.
12-01-2008, 04:36 PM
#11
LSD
The bigger and faster the track, the less you need a limited slip.
But if you are doing any slow tracks (corners) and especially autocross in the 5+ liter cars you need limited slip or you will spend a lot of time marking a line from corner to corner with your inside wheel.
Granted the greater the grip and the less horsepower/torque you have the less it is needed.
Not as much of an issue with the traction of mid and rear-engine cars, but even the factory uses it on their track cars.
Greg Phillips
86.5 928S 5-speed w/LSD
But if you are doing any slow tracks (corners) and especially autocross in the 5+ liter cars you need limited slip or you will spend a lot of time marking a line from corner to corner with your inside wheel.
Granted the greater the grip and the less horsepower/torque you have the less it is needed.
Not as much of an issue with the traction of mid and rear-engine cars, but even the factory uses it on their track cars.
Greg Phillips
86.5 928S 5-speed w/LSD
12-01-2008, 07:31 PM
#12
Drifting
James,
Same James I met at CMP with the black 86.5? This is Mark, the red-headed kid with the multi-colored 928. We have an open diff right now, but I can't wait until I can install a limited slip. My biggest gripe is trail braking with the open diff... unstable in fast corners, and the inside rear will lock up in slow corners (7 at road atlanta, and off-camber right hander at CMP after the horseshoe). Of course, my car probably only has mid-high 200's at the wheels.
Same James I met at CMP with the black 86.5? This is Mark, the red-headed kid with the multi-colored 928. We have an open diff right now, but I can't wait until I can install a limited slip. My biggest gripe is trail braking with the open diff... unstable in fast corners, and the inside rear will lock up in slow corners (7 at road atlanta, and off-camber right hander at CMP after the horseshoe). Of course, my car probably only has mid-high 200's at the wheels.
12-02-2008, 07:58 PM
#14
Race Car
Thread Starter
James,
Same James I met at CMP with the black 86.5? This is Mark, the red-headed kid with the multi-colored 928. We have an open diff right now, but I can't wait until I can install a limited slip. My biggest gripe is trail braking with the open diff... unstable in fast corners, and the inside rear will lock up in slow corners (7 at road atlanta, and off-camber right hander at CMP after the horseshoe). Of course, my car probably only has mid-high 200's at the wheels.
Same James I met at CMP with the black 86.5? This is Mark, the red-headed kid with the multi-colored 928. We have an open diff right now, but I can't wait until I can install a limited slip. My biggest gripe is trail braking with the open diff... unstable in fast corners, and the inside rear will lock up in slow corners (7 at road atlanta, and off-camber right hander at CMP after the horseshoe). Of course, my car probably only has mid-high 200's at the wheels.
Interesting point with the trail braking. When my ABS was disabled, I had single wheel lock ups on occasion. ABS requires less driving talent - glad I have it.
12-02-2008, 11:42 PM
#15
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I started my track experience with an open diff., and besides the issues already mentioned, I also noticed that coming over the top of the uphill at Lime Rock, the 928 would get light and spin one wheel for quite a bit. Tthat was with stock hp. The upgrade to the limited slip eliminated that problem (still with stock hp).
Last edited by Stan.Shaw@Excell.Net; 12-03-2008 at 08:43 AM.