'97 Q45 handling???

A Q45 forum / Cima forum for the President of Infiniti's lineup. Brought to you by Infiniti Parts USA, your OEM source for Q45 parts!
RussBozeman
Posts: 6
Joined: Tue Apr 18, 2006 3:48 pm
Car: 1997 Q45

Post

Hello all. I am new to the forum. Recent purchase of 97 Q45 (non-Touring) 60k miles. Its a pretty car in VG Condition and I Like it a lot but Not all that thrilled w/ handling. Previous owner put 17's: P225 55R17 (I think G35 wheels). Anywhoo, went Fla last wk end and driving in high cross winds. Car was weaving a lot. Not tracking that well, not great turn in, and with body sway. Sprung a little too mushy. I realize they made them cushier about '96 or '97 but they went too far for my taste (more toward the bimmer or G35 is what I like). Any thoughts on tightening things up? Its primarily my wife's so I'm not sure what I can get away with but if there are any cheap n dirty fixes... ? Car has clean history (no wrecks, etc.) though not sure when last alignment was. Except for wheel/tire change no other mods. One other thing...after trip checked tire press and was ~37-38. Adjusted down to 30 as per placard realizing this is for stock 16's which came on it. Any ideas on best press. for this size tire?Thanks in advanceRuss


BadQ45t
Posts: 3255
Joined: Fri Jul 26, 2002 7:54 am
Car: '21 Nissan Leaf SL Plus (wife's car)
'05 Nissan X-Terra S 4x4
'97 Infiniti Q45t SOLD! Miss the old girl
'84 Nissan 300ZX (Original Owner)
'16 Mercedes Benz S550e V8 Power & 35 MPG
Location: Half Moon Bay, CA

Post

I have a 97' Touring which came out of the factory with stiffer shocks and springs and thicker way bar up front (I think) but actually a you have a thicker one in the back.

The good news is there are ways to fix this, bad news is that anything other than stock replacements for the shocks and springs are a PITA to get as they are only available in Japan for the Japanese Domestic Market (JDM). I have 83k and my shocks are for sure shot, the springs are probably still fine.

In any case there are folks on the board that can you out with this. First Kevin Falk (Falkdesigns, do a search) out of So Cal helped alot of us out with lowering springs from Tein, price aroud 300 bucks. They come from Japan, he's married to a Japanese lady so he's got the inside scope. I have already got set of these from Kevin. Second OneTonGarage aka Van Phan out of No Cal just got us sets of KYB high performance shocks, they are pricy (over 600 bucks) and take a while to get (like a few months), but I hope they will be worth it. They are due in anyday, unfortuately you just missed both of them bringing in loads of both from Japan. But they are both pretty active and I expect you can start to save up your pennies and get yourself a set from these guys on the next round.

The other things you should look at are your tension rods, mine were completely shot at 74k and that made a major difference in the feel of the car. You can buy new ones or replace the rubber parts (labor or parts, your call).

I will be installing the shocks, springs and will get some new new sway bushings soon and expect a much stiffer ride with a lower stance. You can get stock replacement parts from Joe at Scotsdale Infiniti, check out the links for Infiniit Parts. Mail order the give great prices.

Mine touring handles pretty well now, but I want more too. The non-Touring were much softer in the cars I test drove back in 2000, a pretty big difference. Worst case start with those tension rods that will fix some of the sloppy feel right away or at least have them checked out. Your shocks are history though, worst case if you don't have the patience install the touring shocks and springs.

There is a place called T3 in Altanta that is well recommended for Q repairs, someone will chime in with their information but they can do the install and check everything out for you.

Than last but not least the tires, not sure what the size of those rims are but that is a bit small, I'd like 245/45 17 which is what I run. I have a set of 19" 06' M45 rims in the garage that are gong on the car with 245/40 19" and with all of that I expect to give 5 series BMW's some grief. I'd look for a set of 18" 02-05 Q45 rims (they will fit out of the box, I have to use spacers) or 20" FX35/45 rims and that will give you alot more meat. Also the sticker the better of course but that means quicker wear and replace. You can probably dump those 17" or just get better tires on them with more meat.

Welcome to the club, you'll like this car once you get it setup.

Q45tech
Moderator
Posts: 14296
Joined: Tue Apr 30, 2002 3:19 am
Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

Post

"thicker way bar up front (I think) but actually a you have a thicker one in the back."

The 97 and later have a somewhat different suspension design.A sway bars stiffness depends not only upon the thickness of the bar but on the length of the right angle bar part that tries to twist it. [other more complicated factors].

The rear bars used on 90-96Q have a 6" right angle twist arm. 97 have a 4" 45 degree section feeding a 5" straight 90 degree section. This appoximates a 9" right twist arm. A 23 mm bar with the exact same shape as a 20 mm would be 47% siffer but legthening the complex twist arm on the larger bar negates the diameter increase.

Same with the fronts, the much longer than 12" [90-96] convoluted right angle twist arm requires a much larger diameter front bar.

Haven't studied the 97 and later much other than these observations.

THe bars twists and convolutions make it impossibble to use the simple bar stiffness equations found on the web. Just as I had to actually use a jig and screw jacks and scales to measure the rear 20mm [90-96] Q bar.

On 97 and later the diameter increases can just be plugged into the equation to appoximate the stiffness increase.

A rear 24mm bar would be 19% stiffer than a 23 mm bar [which is ~~ equal to a 20mm bar on a 90-96 design].


Q45tech
Moderator
Posts: 14296
Joined: Tue Apr 30, 2002 3:19 am
Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

Post

Lowering springs cannot do too much for handling because to be streetable they cannot be stiff enough to reduce sway much.

Larger front sway bars just overload the oem front tires more.

Stronger front tires higher than oem load rating and softer than oem treadwear index will create the most gain. Creating an adjustable front upper spring/shock perch to increase negative camber would be the next step.

You always want the softest springs that will do the job.

User avatar
Falkdesigns
Posts: 2738
Joined: Wed Mar 17, 2004 9:58 am
Car: 1998 Q45t ~ EXE
Contact:

Post

Welcome to the boards and congrats on the car, hope you love it once you sort it out. My Q handles like a BMW M5, but obviously has no where near the power, with the Tein / KYB SR's / tire-wheel combo. It's very tight, very predictable, incredibly stable at high speed with minimal dive under breaking. I can definitely get you Tein springs which drop about 2" from ride height, but they take months as mentioned to get here.

User avatar
elwesso
Posts: 30810
Joined: Sun Feb 23, 2003 4:52 pm
Car: 94 Infiniti Q45t 5 spd
2007 BMW M Coupe
2007 Infiniti G35 S 6MT
Location: Indiana
Contact:

Post

One problem with the Y33 suspension compared to the G50 is the amount of camber gain on cornering.. UNder full compression to get a more optimal amount of camber, you have to run more negative static camber... So, jsut for speculating, stock camber on a G50 is less than -.5*, on a Y33 you may have to run -1* or more to get an optimal contact patch on high cornering...

Not really a bad thing, just a difference in the way it works... May lead to more tire wear, however i run -1 up front and it seems OK so far. Its far more important to make sure your toe is set correctly...

Q45tech
Moderator
Posts: 14296
Joined: Tue Apr 30, 2002 3:19 am
Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

Post

The 90-96 Q45 has a 4.5 degree camber gain [approximately 1.5 more negative per inch of front wheel dive] in turning at 0.8G due to it's high caster and angled multilink [upperlink] impossible to duplicate with a McP front suspension.

Positive caster has its advantages, but it also has a down side as well. When you turn a car left with positive caster the LF rises while the RF drops. This changes the weight on all 4 corners of the car. In effect you're taking cross weight out of the car the more you turn the wheel (taking weight off the RF and LR). The more positive the caster, the more cross weight there is being removed. The more cross weight you remove the looser the car will get. This could be used as an advantage to help free up the car in the corners only when you are turning the wheels. Positive caster will also "create" negative Camber on the outside of the front wheels as the wheels are turned. The higher the positive caster the higher the negative camber gain. Simply adjusting caster may require additional adjustments to camber, depending on the track radius and how much steering is required to negotiate a turn.

Ultralow-profile tire are mosre sensitive to suspension tuning and camber changes. And stiff sidewalls don't conform to road surfaces easily. This makes ultralow-profile tires sensitive to shock, as the short, stiff sidewalls have very little compliance. Harsh surface inputs can make these tires skip and hop across the surgace instead of digging in and finding grip. Large wheel and tire combinations also increase rotating and unsprung weight.

Dialing in negative camber helps combat tread lift and wheel tilt. The trick is to add just enough negative camber so the tread stays flat and 100 percent engaged with the ground under side load and roll. But, adding too much negative camber will hurt more than it helps. Too much negative camber will:

1. Reduce traction 2. Reduce acceleration traction if its applied on the drive wheels 3. Increase the tendency to follow cracks and grooves in the pavement 4. Increase wandering caused by road crown 5. Affect tire wear; the insides of the tire tread will wear faster with more negative camber if you don’t corner hard. Conversely, if you constantly corner hard, your tires will wear more evenly and last longer.

Camber Adjustment Guidelines Driving Style/Front/Rear/

Aggressive Street Driver Multilink/Unequal A-Arm - 1.5, 1 MacPherson Strut - 1.75, 1

Weekend Hot Lapper Multilink/Unequal A-Arm - 1.5-2, 1-1.5 MacPherson Strut - 1.75-2.5, 1.2-1.5

Racer Only or Serious Drifter Multilink/Unequal A-Arm - 2.5-3.5, 1.2-2 MacPherson Strut - 2.5-4.5, 1.5-2.5

http://www.onlineshowoff.com/f...&PN=1


maxnix
Posts: 22627
Joined: Mon Jul 22, 2002 8:11 pm
Car: 1995 Infiniti Q45
1995 Infiniti Q45t
2000 Infiniti Q45

Post

Very interesting.

The rear camber on my wife's FY33 with the 18x9 +35mm OZ wheels and 255/40 PS2 is -1.5°, which is -.1° too negative. I'll check the tread wear, but I am thinking it will not be bad until I get the Eibach springs and KYB SR shocks on.

What a great post on McPherson strut behavior. Probably the pivoting link in BMW serves to reduce this positive camber jacking during cornering.

User avatar
elwesso
Posts: 30810
Joined: Sun Feb 23, 2003 4:52 pm
Car: 94 Infiniti Q45t 5 spd
2007 BMW M Coupe
2007 Infiniti G35 S 6MT
Location: Indiana
Contact:

Post

I like that post Dennis, my Q's alignment is exactly how it should be according to that post..

-1.5 front, -1 rear.

I assume you left out the negative signs in the rear, cant imagine youd want to run +1 rear camber!

Q45tech
Moderator
Posts: 14296
Joined: Tue Apr 30, 2002 3:19 am
Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

Post

Note those numbers were for a double wishbone front:For the 90-96 Q the correct numbers are F -0.75 camber and -1.5 rear camber with a tire whose sidewall stiffness is equal to the oem Michelin Sport XGT-V................lesser tires would probably need -0.5 extra front and rear in oem sizes as you go to 16">17" you can decrease the added camber since these larger sizes naturally are stiffer IF they are 44 PSI MAX TIRES................with 51 PSI tires I would still add -0.25 degrees camber.

Q45tech
Moderator
Posts: 14296
Joined: Tue Apr 30, 2002 3:19 am
Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

Post

With my 235/60/15 my front is -1.4 and rear is -2.0 side to sides with me in drivers seat are within 0.1 degree. New rear subframe and many new arms,

The front has been totally 100% rebuilt with shims to adjust camber.

BadQ45t
Posts: 3255
Joined: Fri Jul 26, 2002 7:54 am
Car: '21 Nissan Leaf SL Plus (wife's car)
'05 Nissan X-Terra S 4x4
'97 Infiniti Q45t SOLD! Miss the old girl
'84 Nissan 300ZX (Original Owner)
'16 Mercedes Benz S550e V8 Power & 35 MPG
Location: Half Moon Bay, CA

Post

If the lowering springs don't do much than why does my 84' 300ZX handle so much better after I put the 2" drop with Eibach install..maybe it is not the drop but the better quality aftermarket and fresh springs theory, either way I think it will help to get a more predictable ride. If you're going to deal with re-doing he shocks my take is get some higher-performance aftermarket springs or at least see if you can fit the stock touring ones on your ride. Ping kevin and get in on the next group buy.

BadQ45t
Posts: 3255
Joined: Fri Jul 26, 2002 7:54 am
Car: '21 Nissan Leaf SL Plus (wife's car)
'05 Nissan X-Terra S 4x4
'97 Infiniti Q45t SOLD! Miss the old girl
'84 Nissan 300ZX (Original Owner)
'16 Mercedes Benz S550e V8 Power & 35 MPG
Location: Half Moon Bay, CA

Post

Bump, he bozzman, you never read any of the replies, you coming back.

Q45tech
Moderator
Posts: 14296
Joined: Tue Apr 30, 2002 3:19 am
Car: 1990 Q45 342,400 miles 22 years ownership with original engine
1995 G20t 5 speed 334,000 miles 16" 2002 wheels - 205/50/16 Sr20ve vvl

Post

Lowering the front and rear on a 90-96 Q increases negative camber by 0.8-1.0 degree . Happiness depends in what you start with and the adjustabilty.

The Q has more camber gain than the 300zx...........minute upper link LENGTH and ANGLE differences............remember 1/8" at third link ~~ = 1.0 degree of camber.

RussBozeman
Posts: 6
Joined: Tue Apr 18, 2006 3:48 pm
Car: 1997 Q45

Post

Jeff, I've read them all and they are fascinating and highly informative. Am trying to decide whether they're too technical for my pea brain. Not sure how far into this I want to go...money, time, etc. I am sure appreciating all of the discussion, tho.

Best Regards, Russ

Chrisfrend
Posts: 89
Joined: Thu Jan 15, 2004 12:04 pm

Post

What kind of tires do you have on it and are they V rated? Some of the mushiness could be caused by tires if they have weak sidewalls. Even the touring model has excessive body roll and rocking front to back. As others have noted, they can be tightened up.

BadQ45t
Posts: 3255
Joined: Fri Jul 26, 2002 7:54 am
Car: '21 Nissan Leaf SL Plus (wife's car)
'05 Nissan X-Terra S 4x4
'97 Infiniti Q45t SOLD! Miss the old girl
'84 Nissan 300ZX (Original Owner)
'16 Mercedes Benz S550e V8 Power & 35 MPG
Location: Half Moon Bay, CA

Post

If you don't want to spend alot but want to get a better ride, go for a new set of shocks OEM, call Joe at Scotsdale Infiniti and order them, see if you can put them Touring ones on. Than buy yourself the best tires you can afford and you'll see a big improvement.

For me the KYB's, Tein Springs and WR rated tires on 19" rims will do the trick.

RussBozeman
Posts: 6
Joined: Tue Apr 18, 2006 3:48 pm
Car: 1997 Q45

Post

thanks, Jeff.

The tires are P225/55R17's on what I think are G35 rims. Traction A Temp B 95T M+S I really like the wheel look so will not change the wheels out...only possibly tire/suspension parts. I am looking through the records..I think the tension rods were replaced recently but no other suspension work in the records.

Another issue...I'm feeling a little wobble under braking...is this a normal mileage for the rotors to warp...(60K?)? Previous owner was an impatient sort so maybe he was heavier on braking?

thanx, Russ

User avatar
elwesso
Posts: 30810
Joined: Sun Feb 23, 2003 4:52 pm
Car: 94 Infiniti Q45t 5 spd
2007 BMW M Coupe
2007 Infiniti G35 S 6MT
Location: Indiana
Contact:

Post

60k is good for Q brakes..... I can feel rotor vibrations after 10k..


RussBozeman
Posts: 6
Joined: Tue Apr 18, 2006 3:48 pm
Car: 1997 Q45

Post

Instead of larger bars, how 'bout just new stiffer bushings?

Russ

RussBozeman
Posts: 6
Joined: Tue Apr 18, 2006 3:48 pm
Car: 1997 Q45

Post

Turn or buy new? Rotors, that is.

Russ

maxnix
Posts: 22627
Joined: Mon Jul 22, 2002 8:11 pm
Car: 1995 Infiniti Q45
1995 Infiniti Q45t
2000 Infiniti Q45

Post

RussBozeman wrote:Turn or buy new? Rotors, that is.
What kind of life do you want? Will you index them, measure hub runout?

BadQ45t
Posts: 3255
Joined: Fri Jul 26, 2002 7:54 am
Car: '21 Nissan Leaf SL Plus (wife's car)
'05 Nissan X-Terra S 4x4
'97 Infiniti Q45t SOLD! Miss the old girl
'84 Nissan 300ZX (Original Owner)
'16 Mercedes Benz S550e V8 Power & 35 MPG
Location: Half Moon Bay, CA

Post

My car got new rotors at 45 and I just turned them again, they need it every 20 to make them feel smooth.

Good luck on the project, end of the month my KYB SR Specials are now in my trunk so that combine with the Tein springs should be on soon. I'll give you a report. FYI, there is a set of the shocks in OneTone's garage that someone did take you could probably score if you jumped on them quick.


Return to “Q45 Forum / Cima Forum”