Hey guys,

I own a 2010 G37xs anniversary edition with 85,000 miles on it, and I've done a lot of research on these forums (and g35driver.com) about suspension, ECU tuning (after mods), and the transmissions on these cars.

I just wanted some opinions on my plans:

1.) Suspension:
I know that the AWD lowering options for non-coilover setups are limited. From my understanding, if you don't want to do coilovers, you can opt for better springs and shocks. The AWD seems to only have KYB-GR2's available as an "upgrade" and are "10-15% stiffer than OEM." Another option is to try Koni yellows in the rear and have Koni revalve my OEM front shocks.

After reading about springs, I've decided that I want to go with IMPUL springs since they give a modest drop. I live in New England and don't care about being slammed, I just want a more responsive suspension, which I'm assuming would come from stiffer springs. To pair with these IMPUL springs, I was going to go with KYB-GR2's since that's essentially the only option. I haven't seen anyone with this combo, although I have seen people with the Swift springs / KYB-GR2 option, which seemed okay but there are such mixed reviews on Swifts that I'd rather stay away.

Of note, I've already upgraded the puny rear sway to a rear sway from a 350Z and liked the results. I think I'll leave the front sway alone as there isn't much width gained from upgrading the OEM G37xs front sway to Hotchkis or whatever. Thoughts?

Random: do spacers for our tucked-in wheels increase driving performance (wider base) more than they increase risk of an averse event?

2.) ECU tuning/exhaust:
I've heard such positive things about the UpRev tune and moderately good things about the ECUTek tune. I've deduced that it's best to do a tune after you've finished engine/exhaust upgrades. When I was younger, I cared about big sound, now I just care about a good exhaust note and reducing any bottle-necking in the exhaust system. I've decided that all I want is a Tanabe axleback and HFC before a tune. I've seen/heard videos of this combo and think it would be a great idea before a tune. Thoughts?

3.) Transmission:
The 7-speed AT on this car just blows. I kind of got used to it doing wacky things. I'm unclear if my transmission computer was ever flashed by Infiniti to the newer updates. I'm not even sure if it'd make a difference as I've seen mixed reactions as well. I'm assuming an UpRev or ECUTek tune would smooth this out? If not, I'll prob bring the car to Infiniti for the re-flash. Thoughts?

There are some other things bugging me like the bluetooth in the car not working well or the likely air leak in the rear passenger window heard on the highway but I won't get into that in this post, lol.

Any thoughts are most appreciated!

 

KSport has gotten pretty decent reviews for the AWD guys that have them on the site, probably cost about the same as new shocks with lowering springs. Not 100% sure how mild they can drop, but might contact member the93owner and see what he says regarding height adjustment range. I think I'd go that route vs. running an oem (or similar) shock w/ lowering springs.

I would recommend the most current TSB applied to your 7AT, it should smooth some of the rough edges and like you mentioned, you've adapted to most of it's issues now.

As far as spacers, should be fine but best to stick w/ known brands such as H&R, Ichiba, and our site vendor B2Autodesigns get good reviews too. If you go w/ bolt-ons be sure to torque to 80-85 ft. lbs, check torque after 50 miles and every oil change (or every tire rotation at the least).

Rather than spacers I'd consider just running your OEMs as-is as a winter set, and getting some lighter 18s w/ more aggressive offsets w/ quality summer tires for the warmer months. The lighter wheels combined w/ sticky tires w/ firm sidewalls will really transform your car when the weather heats up.

Your axleback/HFC combo is a good one, should improve the look and add a bit of pop.

 

Thanks for the response! I was looking at the Ksport as well. They'd be about $300 more than the spring/shock combo I'm thinking of. Do you know much about the Impul springs? From everything I've read, they're a mild drop and make the car feel like "how it should have come from the factory."

I like the idea of forgetting the spacers and getting wheels for summer. Why do you suggest 18 inch wheels?

 

Not a lot of feedback on the Impul sets, so I can't really comment on those. IMO the OEM (or equivalent) shocks aren't engineered to be mated to springs other than what comes from the factory, the length & spring rates are typically quite a bit different.

Konis on the other hand are adjustable and set up for more performance oriented applications, so those combined w/ lowering springs is a solid plan, although the added expense for the AWD fitment would be a con.

18s are a good choice for a mild drop, they look good and open up a much wider range of tire choices/sizes if you go w/ a 8.5 to 9.5" width. Also plenty of lighter weight 18s, and the tires are a good amount less than similar 19 & 20" tires.

Check this thread for some 18s, I've got a couple posts there, first is a square (245s all around), last one is a staggered 245/285 setup.
https://www.myg37.com/forums/18/2765...ic-thread.html

 

I think you're coming up with good decisions. It reads like you've been doing lots of research, and are willing to do more before doing anything impulsive. Got to respect that. Particularly from someone new to the forum.

Brad has given you good advice. (He's been known to do that.) And while I don't have a lot to offer (because of your AWD automatic), I will chime in on your location. If you're anywhere near Boston, I'd put a real high priority on comfort in your choices for suspension and tires. I would hate to have to drive my car anywhere inside the 495 loop. Seems every time I'm near Boston, even in the family car, I'm pretty miserable. I suppose you're used to it, but all I can think of is how much I'd like a luxo-boat for the traffic and crappy roads.

The Tanabe axle-back and a pair of high-flow cats will be fine. Slightly louder, but not obnoxiously so. Although I suspect once you get under the car and look at the OEM catback, you'll be wanting to ditch those pipes. A Topspeed y-back is another reasonable, low-cost option.

I see you're thinking of spacers after the drop, which makes sense. Your 18x7.5" sport rims will look really odd tucked even further behind the fender. 15mm or 20mm spacers will be fine. And no, you won't notice anything better or worse with the spacers properly installed. Just be sure they're hub-centric, and if they're spacer adapters then don't use the crappy half-height lug nuts that come with them. Buy a set of Gorilla half-height spline drive nuts.

After the drop, and the alignment, odds are your camber will be way out of spec. But if it's under -2*, it will probably seem acceptable, too. Don't worry too much about it until you get there, and be open to the possibility that you'll want to throw even more money at the project with camber arms and yet another alignment.

 

Thanks for the reply.

Yeah, I'm in the greater Boston area and the roads are terrible! Especially after a hard winter. Surprisingly, the OEM setup right now on my g37xs doesn't drive too bad on these roads. I'm coming from a G35 sedan with blown shocks, so I'm probably biased

Re: the exhaust, I've looked into the Top Speed in the past and wasn't convinced it was worth my investment. The Tanabe seems high-quality and the fast intentions RHFC with it sounds incredible from the YouTube/member videos on this forum that I've seen.

Re: the installation of the wheel spacers. I read at some point that you have 15mm spacers. How was the install for you? I'm assuming you used a torque wrench to get everything into spec? I'm still hesitant about messing with something so critical to the core concept of a car: the wheels. I guess lots of people run them and no one has lost a wheel on the highway (right?), so maybe I shouldn't be so worried about that.

Still wondering if a tune on stock G37xs will have any great effect in drivability...

 

There are wheel spacers, and then there are wheel spacer adapters. Traditional wheel spacers have extended-length bolts. Wheel spacer adapters are themselves bolted to the hub with the OEM bolts, and have their own bolts that you attach the wheel to. Adapters are a much easier install, IMO.

And obviously you bolt them down with the same care as you would the wheels, in a star-pattern of increasing force, ending things by clicking through with the torque wrench. Also obvious but I'll say it anyway, you need to buy your spacer so that's it's hub-centric, meaning the spacer is a perfect fit over the center lip of your hub.

I use 15mm wheel spacer adapters from B2AutoDesigns. They're on the car in the winter, with snow tires on my OEM 18" sport rims. That means I put them on every November, and take them off again every April, when my Vossens go back on the car. I do this because with my drop and neg-camber, the duckfeet look better spaced out another 15mm. (20mm would be OK, too.)

After doing that dance just twice, I finally rounded a couple of those half-height lug nuts, which was super frustrating. Those little lug nuts are crap. So last year I bought a set of Gorilla 20023SD small diameter, spline-drive lug nuts through Amazon, $22 shipped. Really should have done that right from the beginning.

Coincidentally, this same discussion occurred a few days ago elsewhere. But I'll post the pic again, because it's a pretty cool photo.