G37 Track/Autocross/Daily Alignment
 

Hi Folks,

I understand that there are G specific forums, however, the level of development is much higher here and a G is just a Z 2+2 with a different name. The average level of maturity is also higher than the G forums...

Anyways, back on track:
I have been doing Autocross events in my new Q60 (another name for G37 - Geez Nissan is confused about what they want to call this car!) and the lack of camber is causing a lot of understeer and destroying tyres. I'm signed up for a couple HPDE days in the next few months and before I go and buy a decent set of tyres (RE-11 or RE-71R, still deciding) I want to get an alignment done.

I have purchased a set of SPL front upper camber/caster arms and so now I'm looking for advice on what sort of alignment to get for this car (booked in for tomorrow), allowing that the additional wheel base may (or may not, not sure!) require a slight difference to a standard Z. So far I plan to get the shop to target:
- Front Camber: -1.7 degrees
- Front Caster: Max the arms will allow (6-7 degrees? Any issues foreseen here?)
- Front Toe: 0
- Rear camber: -1.7 degrees
- Rear Toe: toe in 0.08 inch total (0.04 inch each side, is this OK?)

The biggest uncertainties I have are in regards to the Rear Toe and Front Caster. I don't know what Caster these cars can deal with by just adjusting the top arms or what to tell the mechanic to target for rear toe.

The car is my daily (60 miles round trip commute) and I autocross 1-2 times per month and will track probably 2-3 times per year. Tire life on the street is not a goal of this setup, even tyre wear on the track is.

Thanks!
Tom.

If you are going with 0 toe in front, then go for more negative camber up there. I would shoot for -2.5 personally. I run that in my Z, and ran it on the One Lap of America for 3500 miles, with no extra substantial wear on the inside of the tires. Rear toe, I go with 1/16" in total (1/32 per side)

Tracy Ramsey

Hello and welcome to the site.

Click here for OEM Alignment specs.

I purchased the same SPL camber arms that you have.

I told the alignment shop:
- "Keep the rear OEM spec"
- "Give the front -2 deg camber and minimum 6 caster"

They were able to get camber/caster/toe exactly where needed with this kit.
Let me know if you have any more questions!
:tiphat:

If you're doing autox a couple times a month I wouldn't go less that -2.5° of camber in the front. I run -3.0° up front on mine.

Thanks folks!

That's much more camber than I was expecting up front, thanks for the input.

Is 1.7 going to be enough in the back then? Ive been checking temps of the tyres after each autocross run and the back is hotter on the inside at stock camber so was going to leave it there. I will revise if necessary.

It's probably worth mentioning here that the suspension is otherwise standard. The Q60s limited comes with the 'performance tuned sport suspension', which is 2 levels up from base. I wouldn't call it NISMO, but it's more sport than the sport and replaces what used to be called Infiniti Performance Line. It's surprisingly good on the track, not much roll and quite firm, but obviously not coil-over firm.

Well, I went and got the alignment on Friday. Final specs:

Front
-2.4 degrees camber
- 0 toe
- 7.4 degrees caster

Caster is maxed at that camber. With the car running at stock height, the control arms are bottomed out on the adjuster to reach that level, to get more camber I would have to sacrifice caster, etc.

Rear:
- 2.0 degrees camber
- 0.03 degrees toe

There was some miscommunication with the rear toe where I had asked for 1/32 toe in and they interpreted that as 1/32 of a degree, not 1/32 of an inch. Bit of a mistake on both sides, but I didn't know what 1/32 was supposed to be in degrees so I figured it's still toe in and just leave it. Turns out that 1/32 is about 0.8 degrees, so it's got way less rear toe. I won't take it back just yet, I'll try the setup at an event first and see how taily it is, if it's bad then I'll get it adjusted.

I was able to find a couple of pretty nice freeway on-ramps over the weekend and the front is FAR better than before! I was pulling higher G-force that before the alignment without any of that washout understeer. I wasn't going 10/10 as it was a public road, but next event is Saturday and I'm expecting a great change from the really horrible understeer the car used to have.

If I need to change the toe, I'm thinking about maybe picking up one of these:
Align Your Car With SmartStrings, SmartCamber | Smart Racing Products

Probably over-kill, but would allow me to fiddle with the car whenever I like without forking over $100 each time.

How much hotter is the inside of the tire? There can be a little variation, but too much and you're not using the tire completely. And for what its worth, I have ran -1.8 in the rear with RE71R's and seen decent temps. But I also play on a road that is unlike any autocross or road course.

Less than 10 degrees, it certainly wasn't a lot, I just wasn't sure if I should be going with more camber. However, given how much more traction I've got in the front now, I expect I'll be pulling higher total G forces and hence working the outside of the tyre harder. I'll take temps again at the next event to see how it looks and report back.

Less than 10 degrees is good. You don't want to be over that by too much though. Find out how they do at the next one and go from there.


Sent from my iPhone using Tapatalk

On your caster. Is that positive or negative number?

Caster is always positive!

Negative caster would result in dramatic instability, the wheel not returning to center without being directing by the steering wheel and positive camber gain (instead of negative gain) during steering throw.

I like to recall what an old mentor once told me "Caster is faster" :)

For go-fast applications where steering weight is not the main priority for driver comfort, one should pretty much always target max caster possible. In my situation, with stock ride-height I don't benefit from the negative camber gained by reducing the static ride of the car, so to be able to get my target -2.5 degrees of camber, this meant that with the adjustment maxed out on the control arms 7.4 degrees of caster is all that was achievable. With a lowered vehicle it would be possible to get more caster for the same camber settings, I've seen 9 degrees mentioned on this forum for one track racer.

I'll give you a little hint about caster. Cars at one time had negative caster. Some even had a different settings for the left and right. ;) That's the reason I asked the question. I used to do alignments back in the day.

I have the SPL arms too. My settings now are -2 camber and +6 caster. I still have room to go to +8 caster and - 4 camber if I want to.

That was quite a long time ago, when positive camber would generate traction on a very different tyre construction than we drive around on today :)

The track I used to run a few years ago was 8 right hand and one left hand corner. I had my car setup with different camber and caster left to right to account for the variation. Oval cars also run setups dedicated to only turning in the one direct, so varying setup left/right is pretty common today still too.

I digress, but I do like to spend time working on and thinking about these things.

So I got out to the track today for an autocross and the car was great!

My peak G loading went from 1.10 to 1.15 lateral G and my sustained long radius sweeper G loading went from 0.95 to 1.02. That's a 5-7% increase JUST IN ALIGNMENT.

The last time out I was 1.8s slower than a gentleman in a Porsche Cayman S and this time I was 0.1s faster, so I am super happy. Tyre temperatures were good, with the inside about 10 degrees hotter than the outside and the middle temp sitting right iin between with the same pressure as before. Tyre wear is alos MUCH better, with the inside of the front tyres showing wear now where-as before they looked untouched. The understeer is gone and now when the front tyres slip they don't make that high-pitched screech that comes from running on the outside edge, instead they give that harsh shudder that shows the whole tyre surface is in contact and slipping over the concrete.

Unfortunately, I did not have a single clean run, I just could not get comfortable with the rear end of the car, which is not unexpected with 0 toe. I'm going to start bumping up the toe in 0.1 degree increments and see how it goes. It was fast around the tight stuff, but I just couldn't get to a happy place with the front having a LOT more grip than the rear, which is a nice change from the horrendous understeer last time out, but not as fast as it could be. Watch this space.

Last time out:
http://img.photobucket.com/albums/v6...ps3eiinnl8.jpg

This time out:
http://www.houston-bmwcca.com/photos...8-e55d45a1.jpg

Now toss a stiff front swaybar on there and watch the improvement!! Good job!

Tracy Ramsey

Hotchkis front and rear bars makes a huge difference.

I need to stop spending money on this car, not spend more :(

Front bar yes, rear bar no. The Hotchkis rear bar is way too stiff for a proper handling car. Best bet is to just stick with the OEM rear bar.

Yes, ignore all the people who say to get a rear bar. Front bar only needed for this car. I have a whiteline, some have Hotchkis, and there are others. Do your due investigations and choose which you like. There are others, but I personally think that these are your best options.

Tracy Ramsey

Hmm,

If the Hotchkis was a bit cheaper for the front only I think I'd bite...

Plus I'm now thinking hard about a smart string and camber set. If only it wasn't so easy to spend money on cars

Hotchkis bar on front, stock rear bar.

Good info in this thread since I will be getting into this shortly.

So I'm at a bit of a loss here. How does a really stiff front bar help the car, would it not just understeer all over again?! (the issue I was originally trying to correct, for what it's worth)

I understand that you guys use it, but how does a stiffer front end help? I'm in a situation now where there is a TON of lateral grip in the front and not enough in the back. I've got toe adjustment in the rear to fix still and then stickier tyres, but I'll also be going staggered 245/265 RE-11 which I know some of you go square.

It's gets a bit tough with the wheel base difference between the 2+2 and the Z, but I'm not sure I'm going to spring for a stiffer bar just yet, I can't get my head around why it would be a good idea in this scenario.

I have a G37 as well. My setup is Swift/Koni, 265(f)/305(r) tires, stock sway bars. My alignment is around -1.8(l)/-1.5(r) for the front, and around -1 in the rear. Slight toe in in the front and rear. I'm on the stock bars, and I've found that the car is extremely tail-happy. I attribute that to the tires being weak all seasons (Hankook V12's) but mostly, it's really easy to overpower the rear tires. It seems like that's how these cars are - the rear suspension cambers in A LOT under load. Probably for steady-state cornering, but for putting power down, they are terrible. So the car squats, the rear tires camber in, and you go for a slide.

A front bar sends energy to the front of the car. If you are relieving the rear of some energy by making the rear softer (relative to the front), then it is more compliant, and therefore gives the rear a better chance to put the power down. I say relative to the front because as a whole system, the front is now much stiffer, so the rear is the compliant end of the car's suspension system, even though you didn't change anything there. The result is that it allows the car to put power down under load, but still cambers in as much as it did before for steady-state situations, so you gain a lot in the handling department.

Well I caved in and bought myself a Smart Strings alignment system and got under the car last weekend ahead of a Porsche autocross to get the rear end under control.

At my last event I had 0 rear toe, hit 15 cones in 6 runs and threw away the video evidence to keep from being further embarrased. This time I put 1/32" of toe-in on each rear wheel and the result was INCREDIBLE!

The car was just so much better, I am still tingling it was that much fun! So easy to drive on the limit, very forgiving and just smooth. Here is the video from my best run:

https://www.youtube.com/watch?v=q0kbkgL4yRw

I have ordered a Hotchkis front sway-bar which will be here in about 4 weeks :O so I'll get to try that as well.

Interesting note that the rear tyres are hotter on the inside about 10 degrees, but the fronts are hotter on the outside about 10 degrees. I need more front Camber, but I'm maxed out at 2.5 with the 7 degrees of caster. So, standard ride height kind of sucks and I'm not sure I want 3 degrees of front camber driving 60 miles for work each day :( This is why dedicated track cars are so much better when the funds allow :)

The rear suspension has a crazy camber curve built into it. You don't need as much camber in the rear as in the front.

I'm surprised that you are out of travel with the SPL arms.

I'm out because that's how i set it. I wanted 2.5 degrees neg camber and then just bottomed the arms out to get max caster, which ended up at +7.4 degrees.

Once I get the garage floor leveled so I can accurately measure camber then I'll look in to bumping up to perhaps 3 degrees in the front :) I am also toying with the idea of leaving it at 2.5 for now until I get the front sway bar in to the car, the reduced body-roll should help some.

I understand what you did now.