Hello everyone, this discovery was found by one of our member @Lunchtime . He took measurements of both which yielded a difference.

From Lunchtime: G37 Coupe upper control arms on my G35/7 Sedan. Got me around +2 degrees of camber (gained)

I have a 2007 G35 sedan (V36 body). This the pretty much the G37 sedans too. So this information would be useful for G37 sedans as well.

Years back I replaced one of my upper control arms (UCA) with a coupe’s UCA. I noticed that the coupe’s UCA gave my car some positive camber. My sedan was at stock height at this time, so the additional positive camber wasn’t necessary. I put a sedan UCA back on, since I didn’t need the extra positive camber at the moment.

Fast forward to this year. I lowered my sedan a little over 1”, probably like 1.2 -1.4” lower. My fronts currently measure 27” (fender to floor). The car inevitably got some negative camber.

So I thought: Replace the sedan UCAs with the coupe’s UCAs, to perhaps gain some positive camber back into the fronts...for relatively cheap. I got a pair of the coupe UCA for $60.
Using the G37 coupe arms will be great too, as they will retain the aluminum feature of the double wish-bone suspension. (unsprung mass you know)

Yes, I checked before doing all of this. They are different Part Numbers

54524-JK000 upper right Sedan
54525-JK000 upper left Sedan

54524-JL00C upper right Coupe (G37 and 370Z)
54525-JL00C upper left Coupe (G37 and 370Z)

Once I got one side off. I lined up the back bolt holes as best as I could, and you can see that the front ball joints are longer on the coupe compare with the sedan. Coupe is on top





Concerns I had:

Will the coupe’s UCA affect caster?
Will the coupe’s UCA clear the Sedan body?
Can toe still be adjusted back to specs?

I bought an amazon DIY gauge to get my ‘before’ and ‘after’. Joke all you want. But this is just to help me get a before measurement and an after measurement. The difference between the two is the key information I’m going after.

With the DIY gauge:

‘Before’ measurement with Sedan UCA is -2.75 degrees (left picture)
‘After’ measurement with Coupe UCA is -0.75 degrees (right picture)

Both driver and passenger measured the same.

So -2.75 minus -0.75 -> gives us a total of 2 positive camber gained.





Great. But now I have to answer the concerns listed above. Took the car to get an alignment, and I’m glad to say that caster is in spec, toe can still be adjusted back to spec, and camber is in spec. And I have driven the car through speed bumps, did U-turns, etc. The coupe’s UCAs clear the sedan body.








The Shop’s alignment rack measures my front camber at -0.4 and -0.3 (via picture). So if we used the +2 camber value that I calculated at home, we can say that I initially had -2.4 and -2.3 camber to begin with.

In conclusion, you can use the G37 coupe/370z upper control arms on a Sedan, in order to gain around 2 degrees positive. Plus or minus some for margin-of-error.

Considering that Infiniti’s front camber Spec’s have a window of -1.1 to +0.4 degrees. That is a pretty large window. So If the coupe UCAs can get you back into that window. Maybe this could save you some money.

Hopes this helps. This has been on my mind for the past 3 years. And I’m happy to have prepared this for the community.

 

This discovery certainly made me curious about the 3 sets of upper control arms that I had.

Now the 370z and G37 coupe use this control arm.

370z/G37 coupe - JL1
G37 sedan - JK3

I got me a confirmed set of 370z Upper control arms and took the task on yesterday. Though very similar from a distance they are surely different, about 1/2 inch from my Sedan ones to the 370z.

I also took the opportunity to "clock the bushings" ( the OEM arms have a pressed bushing that needs to be tightened at a specific angle so it can aid with the bound/rebound of the suspension)

I was at about -1.5 degrees in the front and though I have not confirmed my new angles, I can tell a difference now. I have known the Upper control arm trick on other chassis for some time now however upon looking at both suspensions from afar you could even say they were the same.

A huge thanks to Lunchtime for having discovered this so now it can be documented and help our tire eating sedan folks who can't fork out $400 on adjustables.



370z/Coupe

Sedan

JK3 Sedan JL1 Coupe

 

Would be interesting with the X. Our stuff is always weird when it comes to the front suspension.

 

I suspect it's specific to Sedan VS Coupe chassis

 

my Z1 FUCA are driving me nuts with the squeaking

 

You should measure your current Z1 length as best as possible and compare to what I posted. Quite possible that it might be close to your current angles.

 

The Z1 design needs to be completely removed to adjust, its a real pain in the butt. My mechanic gave up after pulling it out 4 times. Pretty sure my caster is out of spec right now.

As it sits I have:
Front Left: -1 camber, 7.4 caster, 0.05 toe
Front Right: -1.4 camber, 7.7 caster, 0.03 toe
Rear Left: -1 camber, 0.14 toe
Rear Right: -1.1 camber, 0.19 toe

EDIT: looking at my past alignment sheets before the FUCA, caster was at L 7.6 and R 8.0, so I guess its not that far off from where it was with stock arms.
Either way, I'm going to have to pull both arms off and re-measure everything. The front facing point of the right arm needs to be one rotation shorter, that should get both camber and caster the same as the other side.

 

7 in caster that pretty crazy, I take it your fronts are almost touching the front bumper or the front of the fender?

 

I think the AWD geometry is a bit different. Wheel is more or less centered. A little bit shifted towards the driver.

 

So... Coupe FCA will introduce +2° camber in the front on the sedan?

That's a pretty cool bit of research, and an inexpensive, simple fix to someone who's dropped and doesn't want to d1ck around with adjustable arms. (Hi, hexotic)

That's always been what I've seen here on the forum, that AWD sedans look properly balanced when on the same lowering springs, whereas RWD sedans look too lowered in the rear.

Your sedan looks fitted nicely in that pic. Big meaty tires

 

I love the meat

 

Caster is pretty off, Im sure the alignment shops love trying to put the sensors in the front with barely any room on the back. Your caster is negative and needs to be adjusted forwards a bit.

Off the top of my head looking at the UCA they are at an angle. I think your best bet is to get an OEM control arm and pull your Z1 and match the length to yours and start this way. Never looked at the Z1 arms up close but they appear to have the ball joint off-center which makes sense when you look at the control arm. So it's quite possible that you have them swapped. That much caster on both side with the inability to bring it forwards (other than accidents) means flipped arm.

 

If you look at the pic the angle for both sides is different. Hopefully Z1 labels them or shows what side is what however without instructions and just looking at this picture I could totally F that up

 

yeah theyre installed correctly, but you can adjust caster on them, I think my guy overdid it. Looked at some old alignment sheets, I used to have 4.45 on both sides.

 

You think?