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07-03-2009, 11:51 PM
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Porsche Prophet
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Quaife LSD, GiroDisc brakes
Hey Folks
I have just installed GiroDisc rotors, and a Quaife LSD... looking forward to Homestead on July 18!
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LSD - Limited Slip Differential
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A limited slip differential (LSD) is a modified or derived type of differential gear arrangement that allows for some difference in rotational velocity of the output shafts, but does not allow the difference in speed to increase beyond a preset amount. In an automobile, such limited slip differentials are sometimes used in place of a standard differential, where they convey certain dynamic advantages, at the expense of greater complexity.
The main advantage of a limited slip differential is found by considering the case of a standard (or "open") differential where one wheel has no contact with the ground at all. In such a case, the contacting wheel will remain stationary, and the non-contacting wheel will rotate freely– the torque transmitted will be equal at both wheels, but will not exceed the threshold of torque needed to move the vehicle, thus the vehicle will remain stationary. In everyday use on typical roads, such a situation is very unlikely, and so a normal differential suffices. For more demanding use however, such as driving off-road, or for high performance vehicles, such a state of affairs is undesirable, and the LSD can be employed to deal with it. By limiting the velocity difference between a pair of driven wheels, useful torque can be transmitted as long as there is some friction available on at least one of the wheels.
To see the installation of a LSD style unit Click Here -> Article Forthcoming Stay Tuned |
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2006 Cayman S, Guards Red, Quaife LSD, GiroDisc brakes, GT3 brake ducts, APR UCU upgrade, APR exhaust
04 BMW 330i ZHP Performance package, Imola Red
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02-02-2010, 10:52 AM
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Re: Quaife LSD, GiroDisc brakes
Recalled your post: Reports on performance?
__________________
Craig
425-765-1090, www.Rennstore.com --assistance & discussion for your pad selection welcomed
PAGID brake pads - Daytona 24 hr winners in every podium position
 GiroDisc brake systems and pad spreaders NOW AVAILABLE!
E-mail for any questions: Rennstore@Comcast.net
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02-03-2010, 12:37 AM
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Porsche Prophet
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Re: Quaife LSD, GiroDisc brakes
Totally happy with both mods. I have done DE days at Homestead, Sebring (twice), Roebling (twice) and PBIR.
No issues with the brakes overheating or fading at all - great confidence booster
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2006 Cayman S, Guards Red, Quaife LSD, GiroDisc brakes, GT3 brake ducts, APR UCU upgrade, APR exhaust
04 BMW 330i ZHP Performance package, Imola Red
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02-03-2010, 06:45 AM
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Member of Northeast Group
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Re: Quaife LSD, GiroDisc brakes
I have the girodisks. Very nice improvement over stock. Now if I can just get the pedal firmed up I'll be very happy with the brakes
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Midnight Blue CS...A couple of little tweaks here and there
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02-03-2010, 09:22 AM
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Re: Quaife LSD, GiroDisc brakes
Strange - my brake pedal is as solid as a rock. Do you bleed the brakes after track days. I do, and that does firm the pedal up.
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2006 Cayman S, Guards Red, Quaife LSD, GiroDisc brakes, GT3 brake ducts, APR UCU upgrade, APR exhaust
04 BMW 330i ZHP Performance package, Imola Red
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02-03-2010, 03:11 PM
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Re: Quaife LSD, GiroDisc brakes
Yep I do. Even with a fresh fluid change I get excessive pedal travel. The car always stops but the pedal is so low I have trouble heel & toeing
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Midnight Blue CS...A couple of little tweaks here and there
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02-03-2010, 04:58 PM
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Re: Quaife LSD, GiroDisc brakes
Diverdog,
If you ever figure that out, please let me know. My pedal feels like my Jeep -- pure mush. It has a lot more braking power, but it's still not the way a Porsche pedal should feel.
The older Porsches used to have brakes that felt (and behaved) like real race cars. Very firm, no fade or pedals going soft.
I am "this" close to getting Girodiscs from Craig at Rennstore, Ti shims and TBD (lots of choices with iron rotors!) pads to stop mine from overheating (Yes, PCCBs (at least mine) do that) and the pedal going to the floor.
Our theory is that the iron rotors will be a better heat sink than the ceramics and the Ti shims should keep the heat off the calipers so maybe the pads will not crack and the fluid will not boil. (And this is with SRF!)
I don't see how that will affect the pedal feel at normal temperatures, however. I drove a GT3 briefly and its pedal feel like it should. Now, granted, this was at street speeds, but still it was a LOT more firm than mine.
So if you figure that out, please let me (and others!) know.
Thanks!
Best,
- Mark
__________________
Rare Cayman Cabriolet S in Meteor Gray,
Cocoa top, Cocoa full leather interior, Sport
seats and steering wheel, PCCBs, PSE,
real Cayman 18 inch wheels and a delightful
3.4L engine with a new set of lifters which
seems to have solved the ticking noise.
Last edited by MarkinHouston; 02-03-2010 at 05:00 PM.
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02-03-2010, 05:07 PM
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Re: Quaife LSD, GiroDisc brakes
Originally Posted by MarkinHouston
Diverdog,
If you ever figure that out, please let me know. My pedal feels like my Jeep -- pure mush. It has a lot more braking power, but it's still not the way a Porsche pedal should feel.
The older Porsches used to have brakes that felt (and behaved) like real race cars. Very firm, no fade or pedals going soft.
I am "this" close to getting Girodiscs from Craig at Rennstore, Ti shims and TBD (lots of choices with iron rotors!) pads to stop mine from overheating (Yes, PCCBs (at least mine) do that) and the pedal going to the floor.
Our theory is that the iron rotors will be a better heat sink than the ceramics and the Ti shims should keep the heat off the calipers so maybe the pads will not crack and the fluid will not boil. (And this is with SRF!)
I don't see how that will affect the pedal feel at normal temperatures, however. I drove a GT3 briefly and its pedal feel like it should. Now, granted, this was at street speeds, but still it was a LOT more firm than mine.
So if you figure that out, please let me (and others!) know.
Thanks!
Best,
- Mark
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OK guys, first thing to help brake pedal firmness is mesh/teflon brake lines. They don't expand like the rubber ones and give a firmer pedal. Second is to get all the air out of your brake system. This may take a few cans of fluid and a vacuum bleeder. There isn't much else to do except put some Pagid Yellows on...they're real firm.
I think the mushy feel is air that hasn't got out of the system. Could be in the ABS. If you can't get it, time for the dealer to work on it.
Or a worn master cylinder might be the cause.
Good luck.
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-Sixisenuff
'06 CS;Arctic Slvr/BlkStndLea;Htd Sts;PCM 2.1Nav;PASM;TPMS;SC+;Bose/stuffedsub;CDC4 6CD Chnger;19"CarreraSw/Nitto NT555 F235/40-R275/40;UDPulley;ClutchDelayFix;GT3FrtLCAs;Plenum/4.1Flash;MotorsportVOS;SumpExt;MDSR&LGrills;RndChr mTip;18"BoxsterSRims;/245/40 & 275/40 NT-01 track or Pirelli 240 Winters. Pending:PSCooler;TechartTUVCatback;Heigo Roll Bar
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02-03-2010, 05:25 PM
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Member of Northeast Group
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Re: Quaife LSD, GiroDisc brakes
It is a common problem often discussed here. I had a bad ABS controller, dealer replaced & blead did not fix the mushy pedal. I'm going to look into the hoses. Any recomendations?
I'm using Pagid Yellow on the fronts & black on the rear.The car stops really well, nice initial bite & no fade just mush!
I'm going to have TPC look at it when they do my shocks. They have replaced others master cylenders with a 996 or 997 part.
I'm not familiar with the TI shims. Sounds like a good idea if they are a thermal barrier.
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Midnight Blue CS...A couple of little tweaks here and there
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02-03-2010, 06:27 PM
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Re: Quaife LSD, GiroDisc brakes
Ti= titanium, very clever. I never thought about Ti having a low thermal conductivity. Looks like a great way to keep heat out of the calipers. Great to learn new things on this site!
I want to be sure my brakes are in very good order before I add more HP
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Midnight Blue CS...A couple of little tweaks here and there
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02-03-2010, 06:33 PM
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Re: Quaife LSD, GiroDisc brakes
And dittos on the GT3 pedal feel. I drove a friends 2010 GT3 and it was night & day
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Midnight Blue CS...A couple of little tweaks here and there
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02-04-2010, 08:25 AM
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Re: Quaife LSD, GiroDisc brakes
Asked another way, if you WANTED to design a braking system with a mushy pedal (like many domestic cars, like my Suburban and Jeep) how would you do it?
I am guessing it's a marketing thing -- that some whiz kid marketing MBA right out of school did a survey and found that people (he sure didn't ask me!) prefer a soft pedal. Let's just say that's so, then how did the engineers do it?
Liquids, like brake fluid for example, are not compressible, the master cylinder, unless defective, just pushes the fluid out and into the lines, thence into and through the ABS and more lines and eventually the pistons in the calipers move to squeeze the pads to the rotors. So where is the squish?
Rubber lines that are old and defective could do it, new ones should not. (Do I recall correctly that the Cup car run rubber lines???)
Food for thought...
- Mark
PS: In the search on my car, the master cylinder has been replaced. The ABS unit has not and Porsche doesn't want to throw any more money at it without knowing what it is. And since it won't overheat except on a track and they don't want to hear about that, it remains a mystery. And they claim the mushy pedal is normal for 987/997, not on the GT3/2, though.
__________________
Rare Cayman Cabriolet S in Meteor Gray,
Cocoa top, Cocoa full leather interior, Sport
seats and steering wheel, PCCBs, PSE,
real Cayman 18 inch wheels and a delightful
3.4L engine with a new set of lifters which
seems to have solved the ticking noise.
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02-04-2010, 09:44 AM
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Bronze Sponsor
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Re: Quaife LSD, GiroDisc brakes
MOTIV pressure bleeder - Mark how do you bleed your brakes?
__________________
Craig
425-765-1090, www.Rennstore.com --assistance & discussion for your pad selection welcomed
PAGID brake pads - Daytona 24 hr winners in every podium position
 GiroDisc brake systems and pad spreaders NOW AVAILABLE!
E-mail for any questions: Rennstore@Comcast.net
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02-04-2010, 10:15 AM
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Re: Quaife LSD, GiroDisc brakes
Craig,
I bleed them the old fashioned way.
"Pump 'em up!"
"Okay."
Helper opens bleed valve. Closes it.
"Pump 'em up!"
Etc.
I get no different results from when the dealer does it. And when I say a mushy pedal, I don't mean that it pumps back up. It's just soft. Air (or vapor if it overheats) will let the pedal come back up after a soft initial push. Mine doesn't do that at normal temperatures, so I don't believe I have any air in the system.
When the pedal goes really soft on the track, it comes back after a pump or two on the pedal, so that's vapor. At the calipers, I presume, since that's the source of the heat.
I am thinking the ceramic rotors don't absorb the heat like iron ones and may therefore be transferring more to the pads and then into the calipers. So by using iron as a better heat sink and the Ti shields, maybe we can keep the heat out of the calipers and end the overheating nonsense that shouldn't happen.
- Mark
__________________
Rare Cayman Cabriolet S in Meteor Gray,
Cocoa top, Cocoa full leather interior, Sport
seats and steering wheel, PCCBs, PSE,
real Cayman 18 inch wheels and a delightful
3.4L engine with a new set of lifters which
seems to have solved the ticking noise.
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02-04-2010, 10:31 AM
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Member of Northeast Group
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Join Date: Mar 2008
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Re: Quaife LSD, GiroDisc brakes
I use the pressure bleeder, have had the dealer bleed them to after the ABS unit was replaced (it was defective causing many error codes & no ABS) I'm going to try the heat shields as the problem does get worse with the brakes hot. The pedal never really feels right with cold brakes either.
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Midnight Blue CS...A couple of little tweaks here and there
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02-04-2010, 03:58 PM
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Re: Quaife LSD, GiroDisc brakes
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Now if I can just get the pedal firmed up I'll be very happy with the brakes
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Good luck.
I have had the brakes bled at least 5 times. The master cylinder has been replaced as has the accumulator. I won't know if the last go round fixed it until April when I go to Mid-Ohio with OVR. My fingers are crossed.
For those that have not had this problem be thankful. I was able to put my foot on the floor, no room to slide my left toes under the brake pedal.
I think Porsche may have just over boosted the vacuum assist.
The master cylinder alluded to above is the one used in the 997S or Cayman S with the ceramic brakes. Another member did the switch and had good results.
The thing that amazes me is that the new Cayman S cars that are running in the HSR series have had no reported issues.
The Ti shims will help with heat soak into the brake pistons. However, if were me I'd invest that money in the GiroDisc set. You're going to need pads at some point along with rotors. Sometimes the cheapest upgrades are the ones that cost the most the first time.
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Alan C.
09 CS/PDK/PASM/Sport Chrono/Forgeline 19" ZX3P/FVD Cat Back
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02-09-2010, 10:44 AM
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Re: Quaife LSD, GiroDisc brakes
A general bit of advice:
ALWAYS use at LEAST Motul RBF600 - NOT ATE Blue/Gold for track use.
*These cars boil brake fluid!*
__________________
Craig
425-765-1090, www.Rennstore.com --assistance & discussion for your pad selection welcomed
PAGID brake pads - Daytona 24 hr winners in every podium position
 GiroDisc brake systems and pad spreaders NOW AVAILABLE!
E-mail for any questions: Rennstore@Comcast.net
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03-02-2010, 12:48 PM
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Porsche Prophet
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Re: Quaife LSD, GiroDisc brakes
Does anyone know who sells the titanium plates and how much they are?
Hoping they will help my problem as well.
Edit: just found them here and ordered http://tispeed.com/
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09 CS, PDK
07 Radical SR3
07 Exige
Last edited by RQ_GT3; 03-02-2010 at 12:59 PM.
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03-02-2010, 05:52 PM
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Re: Quaife LSD, GiroDisc brakes
Diverdog, I'm about to install four Stainless wrapped, Teflon Goodridge G-stop flexible brake lines. I thought my brakes were a bit mushy also as compared to my BMW 2004 Z4. A defective master cylinder will slowly leak which causes the pedal to slowly go to the floor but wouldn't feel mushy. I'm betting a combination of residual air and the soft brake lines are your problem.
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Gary
2009 2.9L Guards Red Cayman PDK: Fabspeed mufflers,
Evoms V-Flow filter with partial desnork, 18" Cayman S
wheels, Goodridge G-stop brake lines, Sprint Booster, and
50% tint. Traded in a 2004 BMW 3.0L Z4. Wifey wants a 356!
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03-02-2010, 06:02 PM
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Porsche Purist
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Re: Quaife LSD, GiroDisc brakes
Please let us know if the SS lines help at all.
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Tomasz
Apologies for spelling mistakes, most of them are keyboarding errors. To enjoy this forum I run out of time to proof read.
My garage: 2000 Audi S4 (not stock) | 2007 Porsche Cayman S (FabSpeed Headers, RS60 Tips, SRP 4.1, ATB, GT3 Ducts, GT3 RS Steering & Shifter, Custom Aluminum Look, ZR4)
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