How to Build a Competitive Autocross 350z.
#82
Registered User
iTrader: (7)
Join Date: Jan 2011
Location: corona, ca
Posts: 313
Likes: 0
Received 0 Likes
on
0 Posts
As it sits, I took it to 133 today and it felt super stable despite the front being taller than the rear. I expected lift but there was nothing.
Also, right now I'm running a 400lb rear spring. Since I'm swapping my front springs, I'll also have a 500lb spring available. Do you think I would be better off with the 500lb or 400lb rear? Some more info on my setup: I have Eibach front sway bar at full stiff, and oem bar at the rear. I also have the Eibach bar for the rear in my garage. Tires are 295/35/18 rear and 265/35/18 front.
Thanks
#84
Registered User
iTrader: (7)
Join Date: Jan 2011
Location: corona, ca
Posts: 313
Likes: 0
Received 0 Likes
on
0 Posts
Getting an alignment tomorrow, put the 7 inch springs on yesterday. currently ride height is about 27.25 inches fender to ground in the rear, and 26.25 in the front. This is closer to where I want to be. I would perhaps consider going to down to 27 rear 26 front. The problem I'm running into is that at full travel there is a gap between the spring and the perch, currently about a half of an inch. In order to combat this I am going to be ordering some helper springs.
Here is my recommendation to anyone considering this in the future: get 6 or 7 inch 2.5id coil springs for the front as well as helper springs. 7 inch springs at the lowest setting with helper springs should give you a ride height no more than an inch lower than stock. if you want to go much lower than this, I would probably recommend going with an OTS coilover setup, or for an extra $180 per shock + shipping (more if you want something crazy) send your shocks to truechoice to be shortened and revalved to your hearts content.
Another thing to mention for those that have not done the install before, Most of the guides I saw recommended detaching the UCA to remove the shocks. I did this the first go around for removal, but for reinstall and for my second go around when I swapped the 8 inch springs for the 7 inch springs that it is much easier to disconnect the LCA from the chassis instead. It is a bit a pain in the *** in that it requires the removal of the fender liner and under shrouds, but it is much simpler.
Once I get my helper springs in I think I will write a DIY for anyone else looking to do this, as I went through quite a bunch of trial and error figuring this setup out and it would have been super helpful to see some sort of DIY.
Here is my recommendation to anyone considering this in the future: get 6 or 7 inch 2.5id coil springs for the front as well as helper springs. 7 inch springs at the lowest setting with helper springs should give you a ride height no more than an inch lower than stock. if you want to go much lower than this, I would probably recommend going with an OTS coilover setup, or for an extra $180 per shock + shipping (more if you want something crazy) send your shocks to truechoice to be shortened and revalved to your hearts content.
Another thing to mention for those that have not done the install before, Most of the guides I saw recommended detaching the UCA to remove the shocks. I did this the first go around for removal, but for reinstall and for my second go around when I swapped the 8 inch springs for the 7 inch springs that it is much easier to disconnect the LCA from the chassis instead. It is a bit a pain in the *** in that it requires the removal of the fender liner and under shrouds, but it is much simpler.
Once I get my helper springs in I think I will write a DIY for anyone else looking to do this, as I went through quite a bunch of trial and error figuring this setup out and it would have been super helpful to see some sort of DIY.
#87
Registered User
iTrader: (2)
I just discovered this while installing my setup.
Heck, there's so much pressure that I had to lift both sides to adjust the height on one side. Just lifting one side still kept too much pressure on the place the spring meets the sleeve adjustment. (Because of the sway bar trying to compress it)
No harm in a helper spring though.
Heck, there's so much pressure that I had to lift both sides to adjust the height on one side. Just lifting one side still kept too much pressure on the place the spring meets the sleeve adjustment. (Because of the sway bar trying to compress it)
No harm in a helper spring though.
#88
Registered User
iTrader: (7)
Join Date: Jan 2011
Location: corona, ca
Posts: 313
Likes: 0
Received 0 Likes
on
0 Posts
I just discovered this while installing my setup.
Heck, there's so much pressure that I had to lift both sides to adjust the height on one side. Just lifting one side still kept too much pressure on the place the spring meets the sleeve adjustment. (Because of the sway bar trying to compress it)
No harm in a helper spring though.
Heck, there's so much pressure that I had to lift both sides to adjust the height on one side. Just lifting one side still kept too much pressure on the place the spring meets the sleeve adjustment. (Because of the sway bar trying to compress it)
No harm in a helper spring though.
#89
Super Moderator
MY350Z.COM
MY350Z.COM
iTrader: (8)
You can easily top out suspension, especially the rear. I bet mine come close under braking at times. The street driving can easily do it.
#90
Registered User
iTrader: (2)
As, I mentioned already, I can jack up one side of the car....nothing but air under one of the front tires....and the spring and related hardware are still making contact both top and bottom.
Last edited by Z1NONLY; 12-27-2014 at 05:08 AM.
#91
Registered User
iTrader: (7)
Join Date: Jan 2011
Location: corona, ca
Posts: 313
Likes: 0
Received 0 Likes
on
0 Posts
The kind of forces created during braking are much higher than those created under straight line acceleration. (We are talking NA Z's here) As soon as you start turning and trying to compress one of the fronts, the sway bar starts trying to compress the other.
As, I mentioned already, I can jack up one side of the car....nothing but air under one of the front tires....and the spring and related hardware are still making contact both top and bottom.
As, I mentioned already, I can jack up one side of the car....nothing but air under one of the front tires....and the spring and related hardware are still making contact both top and bottom.
#92
Registered User
Weight saving for STU:
Wheels
Brakes
Seats and rails
Battery
Entire exhaust
All the stuff in the trunk, spare wheel, tools, etc
Aero or decorative plastic stuff undercar and engine
My belly, I can miss a meal
Anything obvious I'm missing?
Also, to make sure, the Nismo diff cover is not allowed in STU? I worry about the heat the Cusco rs diff will generate, not so much in Autocross but longer runs.
Wheels
Brakes
Seats and rails
Battery
Entire exhaust
All the stuff in the trunk, spare wheel, tools, etc
Aero or decorative plastic stuff undercar and engine
My belly, I can miss a meal
Anything obvious I'm missing?
Also, to make sure, the Nismo diff cover is not allowed in STU? I worry about the heat the Cusco rs diff will generate, not so much in Autocross but longer runs.
#93
Registered User
iTrader: (5)
Weight saving for STU:
Wheels
Brakes
Seats and rails
Battery
Entire exhaust
All the stuff in the trunk, spare wheel, tools, etc
Aero or decorative plastic stuff undercar and engine
My belly, I can miss a meal
Anything obvious I'm missing?
Also, to make sure, the Nismo diff cover is not allowed in STU? I worry about the heat the Cusco rs diff will generate, not so much in Autocross but longer runs.
Wheels
Brakes
Seats and rails
Battery
Entire exhaust
All the stuff in the trunk, spare wheel, tools, etc
Aero or decorative plastic stuff undercar and engine
My belly, I can miss a meal
Anything obvious I'm missing?
Also, to make sure, the Nismo diff cover is not allowed in STU? I worry about the heat the Cusco rs diff will generate, not so much in Autocross but longer runs.
#94
Registered User
I can't find that in the rules?? Says Nismo replacement parts are not allowed. A differential cover can be replaced on solid rear axle cars only. Section 14.8G6
Am I missing something? Would love to install the Nismo one.
Am I missing something? Would love to install the Nismo one.
#96
Registered User
I didn't think I would get a reply from SCCA so quick. Confirmed straight axle cars for suspension needs only. I could submit request for clarification or rule change. However it would be unlikely to change. I'm putting the diff back together this weekend with the OEM cover.
#97
New Member
iTrader: (1)
Yeah, it's disappointing. I've talked to a few STAC members personally with the same request, and already had it confirmed as illegal. A full blown diff cooler setup is legal.. but hey, not this cover.
I actually already took a stab at a rule change request.. but i started with Street Prepared board. Can't go adding modifications in ST classes that won't work upwards to Street Prepared.. Unfortunately it didn't seem to get anywhere.
The one i've really pushed for though is to carry down the radiator allowance from SP. You can upgrade any cooler on the car, add just about any you want, but not the biggest one in the front of the car.
I actually already took a stab at a rule change request.. but i started with Street Prepared board. Can't go adding modifications in ST classes that won't work upwards to Street Prepared.. Unfortunately it didn't seem to get anywhere.
The one i've really pushed for though is to carry down the radiator allowance from SP. You can upgrade any cooler on the car, add just about any you want, but not the biggest one in the front of the car.
#98
New Member
iTrader: (3)
wanted your input.
ok i have a 04 350z with a gtm turbo kit making 420 to 500 at rear. getting ready to build a Quaife Differential. so i can ether use the stock Manual 6 speed 3.538 diff or Auto 3.357 diff. i have both sitting in the garage. i use the car for auto x an a few track days. an i was thinking with auto x i find myself bouncing of the rev limiter more then i like too. so i could see where the auto could pick up a few mph with the different gears ratio. just not sure how the compromise at the lower speed if i would suffer.
ok i have a 04 350z with a gtm turbo kit making 420 to 500 at rear. getting ready to build a Quaife Differential. so i can ether use the stock Manual 6 speed 3.538 diff or Auto 3.357 diff. i have both sitting in the garage. i use the car for auto x an a few track days. an i was thinking with auto x i find myself bouncing of the rev limiter more then i like too. so i could see where the auto could pick up a few mph with the different gears ratio. just not sure how the compromise at the lower speed if i would suffer.
#99
Definitely going to want a 3.3 at that power level IMO, especially if you are running something near the stock redline. You may also find yourself wanting a tall rear tire as well. By the end I was running the BSP car up to 7500rpm on the 3.5. That's way beyond the point of known explosion in a DE, but I didn't really care.