997gt3north

mini update

The install was completed today on my new re-valved setup.

Front
- 600# Swift 7 inch linear springs on re-valved shocks

Rear
- 900# Swift 8 inch spring with 150# 6cm Swift Helper Spring on re-valved shocks
- the rear setup was done with the helper spring at the bottom and the main spring above - this was done to work with the dust boot on the OE shock
- The Tarrett Rear Upper Strut Monoball was used
- The new Tarrett (1st of its kind) rear spring hat was used
- we reused the OE washer from the factory setup that is located between the factory spring hat and the factory strut mount - my shop liked the way this mated the 2 Tarrett pieces together

The ride height / corner balance / alignment will all be finished up tomorrow - off to Mosport on Thursday to test it all out (hopefully).



more to come
pictures to follow


Paul

Mvez

Nice, look forward to the track update!

I should be installing the Tarrett rear spring hat soon as well, along with 672# or 728# rear spring, so as to not have to revalve. Nice tip about the orientation of the rear springs.

With the GMG bars, I also thought the 400/600# setup was great with the dampers set to "sport" mode on track. I wouldn't go above 400# front without a revalve though, just to be safe.

I think the 600/900 will be great for hoosiers, but for NT01/RA1 type grip, I think the 400/600-720 combo is just fine, especially with bigger bars.

Guys, this is a "no brainer" mod for anybody wanting to optimize the stock suspension for the track. A simple rear spring hat (which will be available soon from Tarrett) is all you need to convert the rear springs to any linear rate you want using 60mm ID springs. This is WAY cheaper than slapping on a set of Moton's for 6K....and the truth is most of us are still far from maximizing what the stock setup can do anyway.

997gt3north

Last mini update before Mosport tomorrow.

My use of a 620# front spring that is 7" in length would have been better if it was 8" - I knew it was going to be very close but when changing a tire the spring at full droop will not be under load - it will not unseat itself and it really isn't an issue just thought I would mention it. You could easily use a 5 or 6" with zero rate or other higher rate helper to give you some progressive spring feel, but the factory at the front uses no helper and just a linear spring so that is what I wanted to replicate. So, even at 620#s, you still want a 8" length - you likely have to be 750#s+ in the front before you go to the shorter 7" length.

It is starting to rain here - so it could be an action filled day tomorrow - I need some practice drifting so I hope it continues - at least in the morning.

NJ-GT

If you have read post#16, you would not have this problem, and you would be running less unsprung weight.

They key is to use a long helper with the lowest rate, I use a 25# helper, that's all is needed to keep the spring in place. You would need negative 6g force to unset the spring, at least on planet Earth and all its racetracks, this 6g negative force isn't happening.

997gt3north

Mosport Track update with revalved shocks

First I will start with the almost disaster.
- I got my 997gt3 in December of 2006 and almost immediately did the LWFW install
- way back then, no one knew about the difference between the crankshaft pulley being different between the RS and GT3 - I kept the GT3 part and never did the change
- well, at turn 8 coming into the brake zone at 240kph, my low battery light went off, then engine coolant temp went off the scale, and then I lost my power steering doing 150kph in the middle of the turn
- coasted in
- the bolt holding the crank shaft pulley had entirely backed out
- there is a race shop on site - 1 hour later I was back on track with everything fixed
- cleaned bolt, appropriate lock tight, 185#s of TQ to spec
- I have now ordered the RS pulley and corresponding bolt
- could have ended brutally - $100 and I was back in business

The setup - 620#f, 900#r
- punchline, I really, really liked it - it was very easy to drive very fast almost first lap out
- my sway bar setting is Rear GT2 bar on soft hole, stock front bar in middle
- I was very surprised that the car was perfectly neutral with the bars in the same position as I drove with the stock springs and valving
- I would describe the car as almost perfectly neutral - it was very easy to drive at 'my limit' almost from the first lap
- after my research on various spring rate approaches - big split, 100 pound split, reverse split, I went with my gut and input from others and went with 600/900 (620/900 to be exact)
- I will say that I absolutely love the rear 900# - it just feels like the car is being held up better - and this works for many reasons
- if the car was going to live at the track, I think you would want to go to 700#s in the front - as while 620# fixes so much of the front dive under braking and thus makes faster transitions possible - a little bit more would be even better
- I will say again, the rear of the car feels incredible (but the RSS upper and lower control arms clearly are also helping big time if the feel perspective).

I haven't been to the track much this year so I'm a little rusty. Plus, this was the first real day I got to be on the PSS tires. I was just trying the figure out the car, check if my new reduced alignment specs were working, worrying about my re-TQ'd crank shaft pulley bolt - but, according to a spectator while giving a drive to another spectator (they were friends) - we were doing 1:36s on the PSS tires - this is much better than I would have thought possible - given my skills and the PSS tires (and with passenger). I would thus conclude, and I think this was stated by those that mono balled before me, that removing the rubber + stiffening up the springs (taken together) probably cut 2 seconds off my pace today. I have put down consistent 1:35s with Hoosiers in a DE in the past, so given I did 1:36s with PSSs today, I can only conclude the car is easier for me to drive faster.

I will try and post pictures in the next few days of the rear spring setup with Tarrett's new spring hat.

I'm more than happy with the outcome - especially with the car being so neutral right out of the box - and for the $100 fix to what could have been an expensive fix.


Paul

Greygt3

This is a great thread thanks for all the info.

Terry L

This is very satisfying (not the pulley part.) I am curious about the status of the 2 position shocks. Were you running on hard or soft? How does the other position feel? Would you say you have achieved a good street/track compromise, is is it more a smooth track/bumpy track solution?

997gt3north

Terry,

So much of the street / track compromise is a personal thing as you know. I really enjoy daily driving my Q7 - but when I'm in the gt3, I want the full gt3 experience. Daily driving also has a huge effect from the tires - this new PSS makes for a 100% better daily driver - they have a softer sidewall and are great in the wet. When I drove from my city house and city streets to the highways, some good, some with frost heave marks to country roads on the way to the track - the car's character is still GT3 like - it is just firmer. I will say, that to keep it on the streetier side, don't do the rear upper mono ***** as they carry more noise into the cabin.

In terms of soft or hard setting. Similar to the OE setup, what I noticed was when you go for the firm setting, I especially noticed the front dampening would reduce the front nose occilations by about 50%. I drove on the track with 3 red lights (no TC, sport on, firm on). Mosport is a fast and flowing track like Watkins - it isn't bumpy, the braking zones are reasonably smooth - there are cement patches around apexes to change friction levels, you don't hit the curbs (you can touch a few of them) - it is a track that rewards high speed stability and especially subtle weight transfer during high speed to mid speed braking - it is in this area specifically that the car is much better with almost 3x the front spring rate - combined with the fact that the firmer rear spring doesn't allow the car to 'sling shot' forward off the compressed rear springs as much - overall, the car's balance is just much better (in my opinion).

Would my mother like driving this car? No - but almost no one would buy a gt3 as their only car.

I would also like to comment on my driving experience with just the fronts re-valved with 450# springs and stock rear setup versus the 620/900 setup on the car now. What both my mechanic and I noticed was with the first setup, the car would 'unload' it's energy from the compressed 600# rear springs into the now firmer front and you really noticed this - it was a sorta astonishing feel of instant grip turn-in - my mechanic, ex racer, didn't like this as he felt it could unbalance the car at the limit. With the now firmer rear springs and valving, you don't get this unloading momentum feel, the car feels very balanced - just firmer and better (in my opinion).

If the roads you drive on are reasonably good - not perfect but just ok, then it is hard to believe but on the street the car won't feel much different - it does not feel like you tripled the front spring rate and increased the rear by 50% - it just feels more stable.

I will say, this car on Hoosiers is going to be amazing.

997gt3north

One last little update I forgot.

I also ran for the first time the cupcar front lip - cheaper, more flexible, slightly lower, slightly more protruding at the corners. Since I have the RS wing, which I keep at about 12degrees, I have known for a while that it doesn't quite work when track speeds go above around 125mph - ie I could feel the car sort of cavitating from too much rear aero not being balanced at the front - this would hit the car about 3/4qtrs of the way down Mosport's back straight. I'm happy to report that either alone or working in combination with the 900# rear spring resisting the downward rear aero push, the car remained stable - I was very happy with this. This front lip is also so easy to get on and off that anyone with an mk1 should consider this - it's cheaper and that is really all you need to know.

Another final thought is the PSS tires. The first half day I used them, during the Mancation stop in Toronto at Mosport, I was constantly getting into ABS in corners 5a and 8 (the 2 fastest brake zones). I have ceramics and run the Green pads. I knew I had to give the tires a day to get scrubbed before I made a decision about this (was it a pad issue, tire issue, both). I'm happy to report, that for the most part, ABS was a non factor and thus scrubbing off the new tire release formula has made the tires work properly. The last time I really experienced this was a few years back with new 19" R888s - they felt like driving on ice until the release agent was scrubbed off.

For the casual trackday person, my -2.3f, -1.75r seems about perfect for these PSS tires to get abused at the track and yet give you as much rear tire life as possible - the tires were screaming in almost every turn and really held up well - after scrubbing, these tires get my major 2 thumbs up as a combo tire.

Terry L

Thanks for the very informative answer. I infer that you did not try running with the shocks in the soft position on track but used that option to and from the track. Right? It would be interesting to compare lap times in the two positions...maybe next time.

997gt3north

Finally,

Here is a picture as promised of the rear setup.
The key part of this picture is the new Tarett Engineering rear top spring mount.
This new spring mount allows you to change out the rear OE spring to a standard 60mm spring.
You also can see above the rear spring mount Tarett's upper monoball strut mount - this new spring hat will work with the OE strut mount as well as the Tarett monoball mount.

I did a post track day inspection of the PSS tires to see how they looked from a wear perspective with my alignment (-2.2f, -1.75r) - my conclusion is it was near perfect as a street / track setup. It probably could have used on the outer front tire another -.1 or so - but again it was a very good compromise.

I also decided to do a street shake down of the suspension in soft mode without all the track stuff in it - again, I think the 620/900 spring rates with PASM in soft mode when I tried to hit every bump possible was very good at absorbing what came at it.

All in all, I would highly recommend this setup to anyone - along with the RSS rear dogbones and lower control arm with monoball and caster pucks.


Paul

Mvez

Interesting about what you thought when using the stock rears, I noticed the car turns in extrordinarily well too, but I only ran in "hard" damper setting with GMG rear bar in the middle hole.

I'll post my thoughts once I get my Tarrett rear spring hat with 728# springs installed.

mdrums

997GT3north...thanks for the reports ont eh PSS tires. Have you run Sports Cups too? Have you run ToyoR888's? How do the PSS compare to those on the track?

Also I am finding it interesting about the different ideas of shock/spring set up's on these cars....seems like you are running stiff springs....and then a company like exe-tc uses stiff shocks and softer springs.

997gt3north

Yes I have run many sets of OE cups and 2 sets of R888s - this is my first set of PSS tires.

I'll start with the R888s - let's just say, put me in the camp of they are not my favorite tire. For others in different situations, I understand that they can serve as a very good drive to the track semi-slick and are a perfect choice. For me, the first day driving them was basically frightening as all the release agent came out and caused scary handling at certain points. The tread also isn't really going to work in the rain so while it is there, it really is a dry track tire - and as such, it isn't a Hoosier so? Again, I can see if you are in the correct climate and wanted a drive to the track tire that this might work for many people.

The OE cups vs the PSS are basically different points along the compromised dry/wet drive to the track tire spectrum. The OE cup is basically at the maximum point along this spectrum - ie when new, you can get to the track in a downpour if you don't exceed 55mph and the stiffer sidewall and small tread depth are better on dry tracks. The PSS, instead of being at position 10 of 10 on this curve is at position 8 of 10. You get a tire that you could drive when it is actually raining and not worry about hydroplaning off the highway or track (bigger and deeper rain groves). You also get a softer sidewall for daily driving - this actually surprised me how much of a difference in feel this makes inside the car. After a 1/2 day of scrubbing the PSS in, I think it makes a great DE tire (ie arrive, drive, drive home). The PSS is not a Hoosier or Ra1 - not even close. It is however, in my opinion, a far better choice than the OE cup as a combo tire - far better.

If you care about lap times and a legal road tire to arrive and drive on (excluding Hoosiers), the Trofeo is likely to set the lowest times - they don't last long but they will post some low times.

mdrums

Thanks 997gt3north.....so for a guy like me...setting decent lap times driving at 8-9 10ths, just having fun and I drive the car to and from the track.....do you prefer R888 or PSS on the track? From what you are saying it seems like the R888 is still a better track tire than PSS....correct?