Okay I'm back.

I apologize for the delay and thank you for your patience sir. Here are the specs you seek.
Any chance I get to watch the very excellent intro movie to GT1 is one I'll take, so I'm always glad to pop this disc in. And man..I love how fast the menus load...not like GT4! Install a part, and it takes micro-seconds, instead of the 5 to 6 seconds needed in GT4. If you need to go race,
boom the entire menu system is designed so that no matter where you are, you have access to the main menu, race menu, garage, and load/save menu. GT4 sucks in this regard, as it can take a minute or 2 just to locate the area you want.
Anyways, I'm rambling. Here you go. I looked at a couple passenger sports cars (a JZA70-era Supra and a Viper). I also hopped into a full-blown race car, the
Springs: like I said, they vary from car to car in GT1 (and
only GT1).
1. In the Supra, we have
11.6-Front and 5.9-Rear kg/mm for default springs.
2. In the Viper, we have
5.4-front and 4.8 kg/mm rear
Ride Height: These also vary
1. The Supra it's 118 mm
2. The Viper it's 105 mm
From here on down, things become more standardized in both cars.
Dampers: 4/4
Camber: 2.0 [front] and 1.0 [rear]
Stabilizers: 1/1 (soft) 2/2 (med) 3/3 (hard)
Brakes: 7/7
Downforce also varies, apparently. But unfortunately, I couldn't get the specs to "default" in the Viper, since it already had a race-kit installed. But they vary like I said. I didn't have enough money or time to get the Supra modded up. but you get the picture.
For the full-blown race car, I got into a Mitsubishi FTO LM. Unfortunately, it already has a race kit, custom suspension & brakes already installed. And since I played with it in the past, all the settings were not default. I couldn't figure out a way to make them default (tried pushing all the buttons, lol).
Anyways, hope this helps...I need to get to bed, if nobody has posted GT3 default specs, I'll do them tomorrow.