997.1 GT3 - rear unsettled on heavy braking - Page 2 - Rennlist Discussion Forums



997.1 GT3 - rear unsettled on heavy braking

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Old 02-28-2017, 03:29 AM   #16
grrrmonster
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Make sure your shop installs those ramps correctly. Really easy to put them in backwards. As did the guy who put it in my car. Caused a failure. Then put entire Gard unit in. Make sure they speak with Gard about proper installation- just being experienced is no assurance it will be right
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Old 02-28-2017, 12:37 PM   #17
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Quote:
Originally Posted by 911rox View Post
Check the rear toe!...

Diff possibly but toe far more likely...
^ This. Some times an effective diff will mask the problem. But always good to have both items sorted.

Diff parts, go with Guard, effective, good accessibility. Or PMNA, less accessibility for most, cost higher.
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Old 03-06-2017, 10:37 PM   #18
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I'm waiting on the parts from Guard.. not sure if they will show up in time for install/racing.

I checked my alignment specs, running 3.0* toe in total at rear, how does this sound?
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Old 03-07-2017, 12:04 AM   #19
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Most guys seem to run 1.5-2 per side in the rear.
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Old 03-07-2017, 01:33 AM   #20
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Originally Posted by Spyerx View Post
Most guys seem to run 1.5-2 per side in the rear.

Cool! So I'll run with that for now, rather than change too much at once.

Also I just got my Guard LSD internals, what is the best setting?

50/80
40/60

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Old 03-07-2017, 01:54 AM   #21
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40/60 is most common for street cars
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Old 03-07-2017, 08:43 PM   #22
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Quote:
Originally Posted by Spyerx View Post
40/60 is most common for street cars
Many thanks for your input!
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Old 03-09-2017, 02:51 PM   #23
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Originally Posted by Spyerx View Post
No,it's an open diff thet just spins and doesn't allow rear to set.
Also make sure your rear toe is right and in spec and not changing.
As others have said, if you have an OE diff, it's probably toast.

I have a Guards diff in good condition and my back-end wiggles a little under braking from high speeds, I think it's just a 911 thing with the weight transfer honestly... I've spoken with a lot of others with 911s (including non GT) and they experience this too. The GT3 is my first 911 though, so no idea! I'm going to try adding more wing tho, right now mine's in the middle. gotta go full attack I guess

Also check the rear toe settings as was suggested. These tend to slip out of alignment after just a few days on track, especially if you're using R comps. I bought the locking toe plates from Tarett and now at least I know that's not a factor. It had popped out of alignment 2 or 3 times in the past for me - not super fun.
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Old 03-10-2017, 11:52 AM   #24
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On the locking plates... what's weird is I don't have them. Never have. And when I get a set down down the alignment/toe is completely in spec. Maybe my tech has popeye arms. lol. or i don't jump kerbs hard enough.

Sure, i get a little wiggle especially if the braking zone is kinda bumpy, but once I put the GT diff in it was literally night and day on braking AND acceleration. I had to get used to the exit traction I was ***** footing exit apex throttle and needed to drive the car harder to get it to rotate it had so much more traction.
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Old 03-12-2017, 11:15 PM   #25
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I did the Guard Transmission LSD internal upgrade last week, putting the car on the lift and grabbing one wheel, it was just open!

Here is how the install went.

Yup, metal!









You can see wear on the friction disc if look



Guard friction discs on top, OEM on bottom.





GT2 Ramps vs stock 997.1



All done




The install went smooth, and i opted for 40/60 as suggested here.

Aside from this fresh A050 Yokohama (soft compound) went on and I dialled more camber into the existing alignment, now running 3.5* all round.

I had the car out at Sydney Motorsport Park on Saturday for round one of our club super sprint, the car felt great, no wiggles and it was hooked up! Which gave moe confidence to push it, I bought my times down 6 seconds from last outing, frustratingly I did not quite break into the minute 40 zone, but managed a 1:50 lap time. A good time for this car would be about 1:45 at that track, so I am happy to closing in on that number, now I need a good seat, harness, roll bar and to just develop myself as a driver, with this car.








Cheers to all for the advice, very happy with this modification.
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Old 03-13-2017, 10:45 PM   #26
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Great!
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Old 03-14-2017, 12:15 PM   #27
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Nice! Guard diff is next on my list.
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Old 03-15-2017, 08:07 PM   #28
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I had the car at the local Porsche centre on Monday, I asked them to carry out a road worthy inspection (needed annually for our vehicle registration).

They found the RH track rod to have too much play in it, odd as I didn't feel this and it was at an alignment shop on the Friday prior.

So the question is, should I just replace with OEM or is this a great opportunity to upgrade?

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Old 03-15-2017, 08:14 PM   #29
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Which specific component is it? There are a lot of rods/links on these cars.

That's a slippery slope question. I had a PASM damper go bad on mine and left the shop with Ohlins dampers and full monoball suspension. :-)

So, for example, if its the compression link or one of the rear dog bones I'd probably just leave it stock unless you are trying to do some more aggressive alignment things like change the roll center in the rear of the car. If its the rear toe steer or the inner links on the lower control arm I'd monoball those. If the sway drop links, definitely get adjustable links so you can corner balance the car.

Kinda priority list:
rear toe links
sway drop links f/r
a-arm inner links f/r
compression links + a-arm pucks f/r
front steer tie rods w/ bump steer
rotate front shock top mounts
monoball rear shock mounts
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Old 03-15-2017, 10:13 PM   #30
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Quote:
Originally Posted by Spyerx View Post
Which specific component is it? There are a lot of rods/links on these cars.

That's a slippery slope question. I had a PASM damper go bad on mine and left the shop with Ohlins dampers and full monoball suspension. :-)

So, for example, if its the compression link or one of the rear dog bones I'd probably just leave it stock unless you are trying to do some more aggressive alignment things like change the roll center in the rear of the car. If its the rear toe steer or the inner links on the lower control arm I'd monoball those. If the sway drop links, definitely get adjustable links so you can corner balance the car.

Kinda priority list:
rear toe links
sway drop links f/r
a-arm inner links f/r
compression links + a-arm pucks f/r
front steer tie rods w/ bump steer
rotate front shock top mounts
monoball rear shock mounts
You know I think that is pretty good perspective right there ^^, I get caught up and carried away very easy, so I will just stick to the KISS principle and put another OEM unit back in for now.. I personally don't think I am driving at a level where I'd notice any 1% differences yet anyway.

Thanks again for your reply Spyerx
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