6.2 GT3 Suspension Questions

[Pork Chops]

Dampers are being refurbed currently, and a drive in TP993's similar GT3 yesterday tells me my current spring rates are much higher than his, and not necessarily for the better.

Springs are Eibach and the following part numbers were on them

• Rear - ERC or ERO 180.60.140.  6 full coils and 13.5mm thick spring
• Front - 0180.060.0100.  6 full coils and 12.0mm thick spring

Questions

1. What have I got?
2. What is standard in these cars?
3. What is ideal in these cars for mixed driving.  Some sprints, some SMTs, some road, and a Tassie trip 
4. What ride height is ideal?  TPs was pretty much 330mm from top of guard to wheel centre

Now is the ideal time to make any changes if needs be as it's all apart.

Thanks all.

 

[hugh]

You dealing with Cairns? Interested if they have an opinion on this. @spiller or @James P I'm sure would be able to give you some info. 

[Pork Chops]

 

You dealing with Cairns? Interested if they have an opinion on this. @spiller or @James P I'm sure would be able to give you some info. 

Was a very hurried conversation with Toby but I think the quick answer is he doesn't know.

[Ozvino]

Here is what's on my 04 996.2 GT3 - it's a 2 owner 20,000km car, these were fitted by the previous owner (I'm guessing H&R are note oem) - even has the part number visible for you :-)

%5BURL=http://s765.photobucket.com/user/ozvino/media/130C082A-89EC-4252-95D3-A7495F518F00.jpg.html]

 

 

 

[spiller]

I'll have my wheels off tomorrow doing some cleaning and will try and get some pics of what I have. They're a lot firmer than OEM but brilliant on the track. I can take some eyebrow height measurements too...mine is set up with a little bit of rake from memory.

@Ozvino are you sure they're not OEM? I have two spare sets of springs here and they are all red like that. I have wondered what colour the OEM springs are. Maybe I'll check the PET part number against what you have there. Are your front and rear springs both red?

[Pork Chops]

Seems these are the OEM part numbers (from Renntech.org).  Checking the PET it appears these are right but the PET is not specific about which model they are for (Mk1 or 2).  The OEM springs are depicted as a single long spring where as mine are shorter with keepers on them.

The only suss figure below is the rear spring rate for the Mk1 as it's hard to believe it's 30N/mm less than Mk2.  Perhaps it's true.

The Eibach site is rubbish, and I can't find those numbers in my first post anywhere so I'm giving up until I hear from Spiller!

FRONT:

996.1 GT3

PART NUMBER: 996 343 531 91

SPRING RATE: 35N/mm or 200lb/inch

996.2 GT3

PART NUMBER: 996 343 531 95

SPRING RATE: 40N/mm or 228lb/inch

996.2 GT3 RS

PART NUMBER: 996 343 531 97

SPRING RATE: 45N/mM or 257lb/inch

REAR:

996.1 GT3

PART NUMBER: 996 333 531 91

SPRING RATE: 65N/mm or 371lb/inch

996.2 GT3

PART NUMBER: 996 333 531 95

SPRING RATE: 95N/mm or 542lb/inch

996.2 GT3 RS

PART NUMBER: 996 333 531 95

SPRING RATE: 95N/mm or 542lb/inch

[Pork Chops]

 

Had an inkling I had a box of stuff that might be of use. Never properly opened the box until now and I got the car back in 2010...

Somewhat of a barn find!

[TP-993]

 

fantastic. Were they some of the parts you received when you bought the car? Too bad yours are being refurbished right now. 

[Pork Chops]

fantastic. Were they some of the parts you received when you bought the car? Too bad yours are being refurbished right now. 

Yes, yes and no . Happy the standard suspension is being done as it needs doing and I have a feeling the Cup stuff is not for the road. Will clearly check it all out.

[Ozvino]

 

@Ozvino are you sure they're not OEM? I have two spare sets of springs here and they are all red like that. I have wondered what colour the OEM springs are. Maybe I'll check the PET part number against what you have there. Are your front and rear springs both red?

They may well be stock, I just wasn't sure if H&R were oem. Porsche Melbourne did say my car was totally factory and somewhat of a time capsule so that makes sense. You can see from the pic the bolts still have the factory dye on them, so unlikely anything has been removed.

Inthink all 4 are red I'll check in the morning. 

[edgy]

I know H&R is definitely OEM on 997 GT3, I think they may have sourced differently for 996 though.

[spiller]

I begun pulling the wheels off to clean the arches out this morning until my wife put the foot down (I should have done that first before detailing the engine bay and wheels). Will attack them tomorrow morning and get some part numbers for you Nick. I know mine aren't standard, but as I said I also have a couple of spare sets in storage so would like to check those part numbers to see what I have. Thanks for digging up the factory part numbers!

[Pork Chops]

^^ time with our nearest and dearest (cars) is so precious....  Thanks for trying and see details below.  

Essentially what I have in my car is a lot heavier than standard, but half that of the Cup suspension which is triple the stock spring rate so not suitable for anything but track use.  Of all the other left overs I can only consider 2 options for the front which are close to stock / RS rates.  I drove TP-993's car on Weds this week and it felt more compliant than mine, but in a revelation of facts I just got his spring data and it's a little stiffer in the rear, but much stiffer in the front.  I do note (now I have that data) that my car bobs around (like 911s do) at the front so perhaps and upgraded front spring stops that.  But is that better?  The question is what spring set up is ideal going forward, and therefore what valving do I get done on the dampers.  Could the difference in perceived compliance be placebo or perhaps that my dampers are clearly past their best or even incorrectly valved for the springs?

On the dampers, they're going to dyno them before pulling them apart to see how they're currently set up.

Geeky table below (above?).  I physically measured all the stuff I've got.

 

[Pork Chops]

So, here is another table that considers all the spring rates recommended from various forum threads for a 996.2 GT3 taking into account mixed use of fast road and track (yes I've been taking advice from the internet).  Also is my current set up and TP-993's.  Seems that in almost all cases the front spring rate is made to be much closer to the rear compared to the standard set up.  Rear rates went from 700 - 1000lbs so given mine are at 800 that seems OK to me.  Given my fronts are already 571lbs, 600 won't make much difference so 700 would be logical if I'm going to make a change.  You might argue if I'm leaving the rears as is, the fronts are close enough as they are too.  And once again it might be the dampers that will make the difference.

So I think my choices are stay with current, or upgrade the front from 571lb to 700lb.  And in both cases make sure the dampers are valved correctly.

FYI a single Eibach spring 170-60-120 is $125.80 + GST.  That's 170mm long, 60mm ID, and 120N/mm spring rate.  That will be used with my current Tender (not Keeper as I was correct by John at Eibach).  The 170 series have replaced the 180 which is no longer in production, but will fit my car.

Be great to get some feedback from those in the know who've done this before.

[smit2100]

Here is what's on my 04 996.2 GT3 - it's a 2 owner 20,000km car, these were fitted by the previous owner (I'm guessing H&R are note oem) - even has the part number visible for you :-)

%5BURL=http://s765.photobucket.com/user/ozvino/media/130C082A-89EC-4252-95D3-A7495F518F00.jpg.html]

 

 

 

I came across this add, that stamping in the pic looks like its missing a few digits eg 504 at the end.  Do they not stamp the last three digits on the stock springs

I came across this add below.  Looks a pretty good deal, eg cheapest I could find for one new spring was about circa 300.

http://rennlist.com/forums/parts-marketplace/959516-fs-porsche-oem-springs-set-of-4-996-2-gt3-new.html

[Pork Chops]

See the pic of my HR springs. Same part number  but doesn't have F/H. For the sake of Ozvino.

Lets try and keep the thread on track. I'm after 'proven to work' through first hand experience front and rear springs rates to match factory (re-valved) dampers. Also after an ideal ride height.

Cheers.

 

[spiller]

You may also want to to look at some better tow adjustment in the rear if you are still OEM in that dept. The OEM arm is only adjustable via the bolt on the inboard end of the arm which is not ideal because 1) the amount of adjustment is limited and 2) the bloody thing is impossible to lock into place meaning your rear tow can change at anytime (which is damn well dangerous if you take your car on the track - ask me how I know). This could account for some of the instability that you're feeling in your set up (i.e. bump steer)? Anyhow, motorsport toe links and locking plates will take care of that, or many of the aftermarket variants available ex US. 

Pics tomorrow. 

[Pork Chops]

You may also want to to look at some better tow adjustment in the rear if you are still OEM in that dept. The OEM arm is only adjustable via the bolt on the inboard end of the arm which is not ideal because 1) the amount of adjustment is limited and 2) the bloody thing is impossible to lock into place meaning your rear tow can change at anytime (which is damn well dangerous if you take your car on the track - ask me how I know). This could account for some of the instability that you're feeling in your set up (i.e. bump steer)? Anyhow, motorsport toe links and locking plates will take care of that, or many of the aftermarket variants available ex US. 

Pics tomorrow. 

How do you know it's dangerous?  Is the answer in your name, Spiller? 

Anything I do has to be ASAP as I've got a rack day end Nov and the car is apart now!  Any bits you want to sell me?

[spiller]

How do you know it's dangerous?  Is the answer in your name, Spiller? 

Anything I do has to be ASAP as I've got a rack day end Nov and the car is apart now!  Any bits you want to sell me?

When I got the car, it did not have locking plates on the rear toe links, one spin at the track led to the left rear eccentric bolt moving, causing the wheel to toe out. Shortly after this, the inside of the left rear tyre scalloped causing the tyre to fail on a corner at 190 km/h with a 720 and backwards into the infield. Not fun! Locking plates fitted and it hasn't happened since. 

Check your rear toe links...if they are a solid cast arm then they're OEM. If they're threaded on one end then they're adjustable which is what you want. You also want locking plates which replace the adjustable eccentric bolt with a solid bolt that "locks". Then all of the adjustment is done via the threaded portion of the rod.

http://rss.rpmware.com/rss/rss-adjustable-rear-toe-steer-kit/g-62404.aspx

^^^ these guys are good and their shipping is fast. I recently received their engine mounts...3 days to arrive.

BTW: It turns out my suspension is exactly the same setup as yours! I assume this is the early cup car stuff (non adjustable dampers)? Unfortunately I couldn't get a part number for the front springs but the rears are 170-60-0190. I assume this means they're 190 N/mm? The helper spring is 50 N/mm so not sure if this is added to the rate of the main spring when considering overall rates?

[Pork Chops]

When I got the car, it did not have locking plates on the rear toe links, one spin at the track led to the left rear eccentric bolt moving, causing the wheel to toe out. Shortly after this, the inside of the left rear tyre scalloped causing the tyre to fail on a corner at 190 km/h with a 720 and backwards into the infield. Not fun! Locking plates fitted and it hasn't happened since. 

Check your rear toe links...if they are a solid cast arm then they're OEM. If they're threaded on one end then they're adjustable which is what you want. You also want locking plates which replace the adjustable eccentric bolt with a solid bolt that "locks". Then all of the adjustment is done via the threaded portion of the rod.

http://rss.rpmware.com/rss/rss-adjustable-rear-toe-steer-kit/g-62404.aspx

^^^ these guys are good and their shipping is fast. I recently received their engine mounts...3 days to arrive.

BTW: It turns out my suspension is exactly the same setup as yours! I assume this is the early cup car stuff (non adjustable dampers)? Unfortunately I couldn't get a part number for the front springs but the rears are 170-60-0190. I assume this means they're 190 N/mm? The helper spring is 50 N/mm so not sure if this is added to the rate of the main spring when considering overall rates?

Thanks for that info.  Yes, 190N/mm which is 1085lb/inch, which is up the heavier end of the scale for a road / track car.  Certainly heavier than my 800 rears.  Are you saying your is the same as my Cup stuff?

Keepers you can squish in your hand, and Tenders have a proper spring rate so suspect yours are Tender springs.  Apparently they work best when they have about 10-15mm of travel left in them when the car is stationary.  This handles the small compressions, and apparently allows the damper in rebound to respond better.  I'd doubt they add to the overall spring rate as once compressed solid, it's all about the main spring.  So the Tender is all about transitions but once a side or corner is loaded the main spring does all the work.  

Caveat.  I'm self learning by reading the internet and using common sense.  While I think I've got this right, there are certainly wiser owls around to provide advice and indeed correct me if I'm off path a little.

[Pork Chops]

This look exciting...EDIT and expensive!

http://rss.rpmware.com/rss/rss-tarmac-series-supsension-kits/g-76869.aspx

Spiller, what would you pick out of this kit to represent best bang for buck.  Rear toe steer kits and 1 other.  To keep the budget half reasonable.

[spiller]

Thanks for the info re: the tenders, that makes perfect sense. It appears that my stuff is exactly the same as your cup stuff, same shock body, colour, shape etc. The only difference is my collars are a different colour. I am not sure if mine have been revalved to suit my particular spring rates or not. I can say they're great on track but you probably wouldn't enjoy them on the street, they're too stiff for bumpy back roads.

I thought you'd go looking through the RSS catalogue :p. All of that stuff is worthwhile but if picking two I would say the toe steer kit and the rear LCA's (because GT3 already has adjustable front LCA from factory from memory but not rear). That should allow you to get the rear set up perfectly for whatever ride height you set. Just my opinion, it can't hurt to speak to one of the local race shops who have experience setting up GT3s (there would be many in Melb I assume)!

I will measure my ride heights for you to give you an idea.

 

 

 

 

 

 

[Pork Chops]

This website is interesting as Tarret sells packages that move from basic and cheap to extensive and expensive. The nice thing is as you go through increasing the options, you see what parts gets added and therefore some idea of the order of importance and bang for buck. 

http://www.tarett.com/items/un-assigned/996GT3-SuspensionPackage-996GT3-detail.htm?Count_Class_2_7092630=10251075&Count_Class_5_7092630=10251051&Count_Class_6_7092630=10251083&Count_Class_8_7092630=10251085&Count_Class_9_7092630=10251057&package=Club-Sport A&repost=1&start=0#ITEM_7045879

My budget goes to Club Sport A.

[Pork Chops]

You might find this thread interesting if you're looking for the same answers I am.

http://rennlist.com/forums/996-gt2-gt3-forum/933115-996-gt3-alignment-setup-thread.html

 

[spiller]

Going to go with Kussmaul settings? Seems like the perfect "fast road/odd track day" set up.