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GT Car Alignment Specs - Share your set-up / knowledge
Thought I'd start this topic for those looking to understand / share their knowledge re: how to adjust the stock or modded suspensions to specific alignment specs. From what I understand, the max alignment spec of the GT4 without any mods (i.e. shims, toe links, etc.) is:
Front: -1.8 or -1.9 (set with 0 Toe)
Rear: -1.5 (set with .080 Toe)
It would be great if someone could post their alignment spec/ print out showing these max adjustments but also showing their caster + thrust angle etc. and what those should be.
In addition, any knowledge that can be shared of your ideal track vs. road & track set-ups would be great.
I'm 99.9% sure the settings of the 981 GT4 will translate to the 718 GT4......from my personal experience these cars need more camber and you will also need to adjust the toe, specially the rear so you don't get that instability feeling when braking at high-speed hard.
Also, a good alignment will help improve tire life at the track without affecting street ride.
My initial setup was -2.5 degrees front and -2.0 degrees rear. Zero toe front. My rear toe is different than most as I used the TPC toe links which diminish toe change with suspension movement (highly recommended).
Also added 7 mm RSS front spacers to gain back some track and help with understeer.
At this stage we used only shims to adjust the camber and on the front moved the OEM camber plate....once you cross -2.5 on front the caster gets way out of spec but at -2.5 you should be OK.
My second stage for alignment was -3.0 front and -2.5 rear with a little bit of toe out on the front for better turn in. this was the best alignment for track duty so far with stock tire/wheels....the previous one is a better compromise between track and street.
Now, I haven't received my 718 GT4 yet but on the 981 GT4 you had to deal with understeer and the best solution was to go with bigger tires up front. I know adjusting the sway bars is possible but that's a band aid for a problem like this.
So I ordered some Forgelines 19x9 and 19x11...front one is 0.5" wider just like on the GT3s....another way PAG handicaps the GT4. Tires I went all out with Pirelli DH slicks in 265 front but there are other tires that you can use and wider will fix most of the problem of understeer.
Now, to fit that front tire you will need camber plates so you can tuck that tire inside the fender. Don't try to run this combo only on shims, you can hit the front fender edge. You max out the camber plate inboard and use as little shims as possible to get to you front camber setting. Also the camber plates correct the caster and you use less shims on the LCA.
Tu sum it up.....you will need various shims in different sizes. RSS sells a kit that's very nice and have the most common sizes.
You will need rear toe links....these can be from Tarrett, RSS, BBi, TPC, etc.....but I highly recommend the TPC rear toe links due to the offset design to minimize toe change.
Since you have rear adjustable toe links taking out the OEM eccentric for rear toe adjustment and swapping a lock-out kit is optional.
Another optional mod is to add the DSC Sport controller....this will convert the GT4 suspension to fully active...also recommended.
Hope this info helps and on the 981 GT4 forum there's lot of info on this subject.
I'm 99.9% sure the settings of the 981 GT4 will translate to the 718 GT4......from my personal experience these cars need more camber and you will also need to adjust the toe, specially the rear so you don't get that instability feeling when braking at high-speed hard.
Also, a good alignment will help improve tire life at the track without affecting street ride.
My initial setup was -2.5 degrees front and -2.0 degrees rear. Zero toe front. My rear toe is different than most as I used the TPC toe links which diminish toe change with suspension movement (highly recommended).
Also added 7 mm RSS front spacers to gain back some track and help with understeer.
At this stage we used only shims to adjust the camber and on the front moved the OEM camber plate....once you cross -2.5 on front the caster gets way out of spec but at -2.5 you should be OK.
My second stage for alignment was -3.0 front and -2.5 rear with a little bit of toe out on the front for better turn in. this was the best alignment for track duty so far with stock tire/wheels....the previous one is a better compromise between track and street.
Now, I haven't received my 718 GT4 yet but on the 981 GT4 you had to deal with understeer and the best solution was to go with bigger tires up front. I know adjusting the sway bars is possible but that's a band aid for a problem like this.
So I ordered some Forgelines 19x9 and 19x11...front one is 0.5" wider just like on the GT3s....another way PAG handicaps the GT4. Tires I went all out with Pirelli DH slicks in 265 front but there are other tires that you can use and wider will fix most of the problem of understeer.
Now, to fit that front tire you will need camber plates so you can tuck that tire inside the fender. Don't try to run this combo only on shims, you can hit the front fender edge. You max out the camber plate inboard and use as little shims as possible to get to you front camber setting. Also the camber plates correct the caster and you use less shims on the LCA.
Tu sum it up.....you will need various shims in different sizes. RSS sells a kit that's very nice and have the most common sizes.
You will need rear toe links....these can be from Tarrett, RSS, BBi, TPC, etc.....but I highly recommend the TPC rear toe links due to the offset design to minimize toe change.
Since you have rear adjustable toe links taking out the OEM eccentric for rear toe adjustment and swapping a lock-out kit is optional.
Another optional mod is to add the DSC Sport controller....this will convert the GT4 suspension to fully active...also recommended.
Hope this info helps and on the 981 GT4 forum there's lot of info on this subject.
I'm 99.9% sure the settings of the 981 GT4 will translate to the 718 GT4......from my personal experience these cars need more camber and you will also need to adjust the toe, specially the rear so you don't get that instability feeling when braking at high-speed hard.
Also, a good alignment will help improve tire life at the track without affecting street ride.
My initial setup was -2.5 degrees front and -2.0 degrees rear. Zero toe front. My rear toe is different than most as I used the TPC toe links which diminish toe change with suspension movement (highly recommended).
Also added 7 mm RSS front spacers to gain back some track and help with understeer.
At this stage we used only shims to adjust the camber and on the front moved the OEM camber plate....once you cross -2.5 on front the caster gets way out of spec but at -2.5 you should be OK.
My second stage for alignment was -3.0 front and -2.5 rear with a little bit of toe out on the front for better turn in. this was the best alignment for track duty so far with stock tire/wheels....the previous one is a better compromise between track and street.
Now, I haven't received my 718 GT4 yet but on the 981 GT4 you had to deal with understeer and the best solution was to go with bigger tires up front. I know adjusting the sway bars is possible but that's a band aid for a problem like this.
So I ordered some Forgelines 19x9 and 19x11...front one is 0.5" wider just like on the GT3s....another way PAG handicaps the GT4. Tires I went all out with Pirelli DH slicks in 265 front but there are other tires that you can use and wider will fix most of the problem of understeer.
Now, to fit that front tire you will need camber plates so you can tuck that tire inside the fender. Don't try to run this combo only on shims, you can hit the front fender edge. You max out the camber plate inboard and use as little shims as possible to get to you front camber setting. Also the camber plates correct the caster and you use less shims on the LCA.
Tu sum it up.....you will need various shims in different sizes. RSS sells a kit that's very nice and have the most common sizes.
You will need rear toe links....these can be from Tarrett, RSS, BBi, TPC, etc.....but I highly recommend the TPC rear toe links due to the offset design to minimize toe change.
Since you have rear adjustable toe links taking out the OEM eccentric for rear toe adjustment and swapping a lock-out kit is optional.
Another optional mod is to add the DSC Sport controller....this will convert the GT4 suspension to fully active...also recommended.
Hope this info helps and on the 981 GT4 forum there's lot of info on this subject.
thats one of main reasons the forum worth to read is people like you jmartpr you cut to the chase and made summery of perfect answer, thanks!
thats one of main reasons the forum worth to read is people like you jmartpr you cut to the chase and made summery of perfect answer, thanks!
You are welcome....the good thing is that all these settings have been tested for several years on the 981 GT4, so there's a good consensus on what works and what doesn't.
Finally I did wheel alignment at a race shop... stock was:
- Front Camber: -1°30' - Front Caster: +9°30' - Front Toe: +1mm total - Rear Camber: -1°30' left, -1° right - Rear Toe: +2.5mm total
We added 7mm shims on front LCAs (now there is a total of 16mm shims each side), here you are the results: - Front Camber: -2°00' - Front Caster: +10°10' - Front Toe: 0mm - Rear Camber: -1°30' left, -1°20' right - Rear Toe: +3.5mm total
Yeah that's me and my car. I had this experience with my 718 Spyder. Still there is some understeer, maybe +10° caster is too much and one should reduce it to +9°30' while keeping camber -2°. Or to play with sway bars... mine are still middle/middle.
My mechanic just did my 718 GT4 and was able to get -2.2 camber front with shims but couldn't get the rear past -1.3 without a rear toe link kit, he had to install and modify custom parts they use on cup cars to get to -1.8.
What about lowering as well? I understand that the suspension has coil-overs and we can adjust the ride height.
I'll let you know how it goes. Mine is being lowered 10mm as we speak after i read 4midable thread. I was going to have the dealer do it, but It was going on an enclosed truck and didn't want a potential problem getting it on a truck ramp. I'm having a race shop do it. Seems to add a bit more aggressiveness
I'll let you know how it goes. Mine is being lowered 10mm as we speak after i read 4midable thread. I was going to have the dealer do it, but It was going on an enclosed truck and didn't want a potential problem getting it on a truck ramp. I'm having a race shop do it. Seems to add a bit more aggressiveness
nice, and let us know as well how it is on dip / driveways / other inclines (like getting into a gas station).
Of course when you lower the car, you will get more negative camber as well.
Jmartpr, what offset are you running on your wheels? I want to be able to put 265/35-19 on the front as well, but with comp-R street tires. Some 305/30-19s on the rear to balance out the ride height should make for a nice increase in rubber to the road. That gives 20 mm more in the front and 10 mm more in the rear, which should help balance out the understeer issue.
I run 255/35-19 and 285/35-19s on my Cayman S. When I try a 245 on the front the beautiful balance declines into a bit of terminal understeer and I can't throttle steer like I want too. It is interesting how adding more front end grip (10mm wider tire) actually allows one to put down more power to the rear wheels, achieve some free car rotation with slip angle, and ultimately have more grip in the rear too.
08-09-2020, 11:40 PM
GT Car Alignment Specs - Share your set-up / knowledge
