Q45 rear stabilizer bar installed!

[landtodd]

Q45 rear stabilizer bar installed!

I finally installed the Q45a rear stabilizer bar that I bought from Scottsdale (kit ~$250) on my '92 Q45. Installation was easy. I unbolted the exhaust from the middle to the back (three nuts, three bolts), let the exhaust hang, twirled the bar in, and it bolted right up. The kit included the bar, backets, bolts, end-links, and bushings.

There was a thread earlier about my experience with the Scottsdale kit, so here's an update . . .

On the first try, my kit was missing the four $5/ea. body bolts. This is what derailed my first attempt at installing the bar. If I had known the bolts' specs off the top of my head, I would have purchased them locally. Joe FedEx'd them at no charge. Everyone makes mistakes -- Scottsdale gets an "A" for dealing with it.

Later, when I started looking at part numbers, I discovered that my kit contained shock bushings when I expected sway-bar end-link bushings. I asked about that. Brian said that these were a direct replacement for the bar bushings. Dennis was skeptical. See, I don't know -- yes, they are the right size, but I don't have a durometer or access to Infiniti service bulletins. The shock bushings are missing a shoulder that centers the bar bushings in the hole, and the bar bushing is 3x the cost of the shock bushing (a clue?).

Leaving that discussion behind, I knew that I was likely to replace whatever bushings they sent with urethane anyway, so I decided to try the shock bushings they sent. In the final (driving) analysis, I suspect they're on the soft side. That said, once the bushings do compress, the bar makes a difference. Body roll is reduced. By how much it's hard to say. It feels as though there's a definite point (the bushings compress) where the body almost stops rolling (compared to stock). It's a positive change.

Dennis' explanation of "roll axis" feels right. Without the bar, the car feels like it stands on the front end in a turn (plowing, understeer). With the bar, the rear roll center is lowered, bringing the car's overall roll axis closer to horizontal. Indeed, it feels like the rear is doing more work. The car feels flatter in a curve.

Off to buy those urethane bushings . . .

[911/Q45]

Good work! Let us know how the urethane bushings feel.

[Q45tech]

The 1" wheel to 1/4" bar attachment point is the ratio to keep in mind. The body could roll 3.5" without a bar but the endlink will only move 0.875" in total [up or down].

How much does the 1,2,........3,4 bushings compress before they start transferring anything to the sway bar.

See the problem of fine adjustment ......if each of the 2 on each side had only.......0.21875" of play the bar would not be engaged period nothing no affect.

Urethane will be dramatic vs soft even hard rubber!

You must think about 0.02 ~~~20 thousands of an inch as the maximum acceptable play in the system.

[Q45tech]

http://www.me.udel.edu/meeg467...s.ppth ... 67...R.ppt

[Q45tech]

The 20 mm rear bar can be providing almost nothing due to the total 1.0"--------0.5" slack but even the softer shock bushings have some stiffness to compression.I can't stress this enough!!!!!!!!!!!!!!!! if you can squeeze the bushing ANY between your thumb and forefinger it is TOO SOFT.

The stock oem end link threads and washers and bushings are a system designed to yield about half the available bar stiffness.....not the calculted 40# wheel rate but #20 in real life at least for the first month when everything is new. Down hill from there!

The Stillen 24 mm solid bar came with urethane and thicker endlinks so formulae says the bars are 40# vs 120# but the 20mm as installed with oem components may only DELIVER 20#-25# not the 40 pound/inches possible.

I use metal washers at each end of each [8] bushings to precompress the bushings to enable the bottom/top nuts to fine tune the bar coupling in the zero to 40 pound range............a half a turn can be felt and every month or so I am retightening to correct for wear...........the looser you couple the bar the less the wear.

Unfortunately we have few choices the hard [24-Pappy Bear bar] or the soft {20-Momma Bear bar}...........no Goldilocks middle ground 22 mm bar or better yet a 22 with 3-4 adjustment holes [unfortunately the short 6" arm on the bar makes holes or adjustment impractical due to angles they would create].

Of course my changing to the smaller 28 mm front bar [vs 29mm] immediately made the rear APPEAR 6.5% stiiffer [ratio that is shifted from the front].............really is tricky to get and maintain the ratio I want.When you get things balanced so that as the fuel is used YOU can feel the change in handling you know you have it right. 120 pound changes

NASCAR guys say they can feel a 1.0 psi tire pressure change....thats a 2.5% change in sidewall stiffness vs a 5% change in roll stiffness for a full to empty fuel tank.

I'll bet most drivers are so insensitive that a 10% or 20% [even a 30%] change would go unnoticed.

Can you feel the difference when a single rear passenger is added ? How about with 2 set of golf clubs added to trunk?

[reggiegsd]

I believe some of our members are auto Xers. An experinced Solo II driver can feel a pound or two of air pressure and can even tell a change in temperature.

The best money you can spend on your car is to upgrade the driver.

[911/Q45]

Boy that's the truth! Pretty frustrating to have 200 hp on the guy in front of you on the track and be unable to keep up due to his superior skills.

[landtodd]

Can you feel the difference when a single rear passenger is added ? How about with 2 set of golf clubs added to trunk?

LOL! Noone will ride with me yet. They said "The new bar means you're cornering *faster* now? No thanks."

I've been meaning to take up golf so I can fine-tune the suspension . . . :-)

More as it develops.

[DAEDALUS]

I'm wondering why the manual doesn't give a torque value for the endlink nuts. Ignoring running torque, there is a direct relationship between torque and preload for a given stud size...seems the easiest way to define the right amount of preload is to define a torque range. I know the calculations aren't terribly accurate to go from one to the other, but without anything better, it'll do. My gluteometer isn't calibrated well enough to discern 1/2 turn difference! The Chilton's manual for my Firebird calls out 11 ft-lbs of torque on the endlink nuts. To me this seems a little too high for stock rubber, but I really don't know.

[Q45tech]

Missing the point, the endlinks are not threaded all the way! Bottom the nut will ALWAYS leave "X" space for the correct bushing! It is barely compressed ANY.My trick with 4 washers means you can compress the bushing by 25-50% destroying its longevity but removing all the play and more [bust out the sides of it if too aggressive in tightening].

Urethane of the correct size so that the nuts cannot bottom against the threads obviously has little give so the endlinks might bend if you don't get it just right.

I have seen the 24 mm Stillen end links which are 2-3 times as strong bend and permanently deform under a mishap.

If the midpoint of the lower arm can only move [1.0000000" when the wheel droops 4.000"] .....the bar only twists +- 1.000" TOTAL.

A 5% assembly error [0.05"] per side would be good but I measure oems as doing nothing in the first 1/4 of an inch [1.0" wheel movement.

This is by design so that the first 1.0" of body roll or hitting a one sided 1.0" bump means the springs not the bar are interacting. Then the bar comes in as the rubber bushing gets compressed.....same with front bar except there are only 2 bushings per side [again with only enough thread to leave the bushing sloppy].

So one car may have a 268 lb/in roll stiffness [springs alone] and another might be 400 or 520 or 320 or 350 or 440 or 295......plus the difference in sidewall stiffness and inflation.

This is a lack of precision but means the car rides over bumps well/or not and agressive turning eventually engages the bars or not.....it means a wishy washy plus or minus 1.0" of body roll then some progressive roll restraint.

I like to feel the bars working from day one, I like to feel the tires working...........sudden over or understeer changes or non predictability scares me because the car weights so much recovery is not guaranteed..........polar moments [how much mass is beyond the springs at each end]........things in the trunk must be restrained as a shift can cause real problems.

Many wouldn't notice whether a car rolled 1 inch or 2 inches in the same curve at the same speed......I can assure you that a 122 pound difference on a single rear tire means a +-10% difference in maximum available traction side to side and this is more than enough to get you in trouble in bad weather much less on ice!

For those who don't believe the front [rear] shock tower flex I am constantly retreading the Stillen brace as the different forces eat out the threads where the HELM joint screws in [the aluminum bar is softer than the bolt]..........I had the bar let go in the apex of a turn and the camber must have changed at least 1/2 a degree immediately.

Trying to make a silk purse out of a sows ear [bowl of rice]?

[landtodd]

Incremental improvement here, incremental improvement there. I'm not having the best luck finding the urethane locally in close-to-correct size, but there are still a couple of places left to look. Everybody's got the larger stuff for dopey American cars.

I'm sold on the bar! Plenty of experimentation left to do. A big part of the fun is how easy it is to make a difference in the way the car handles. Quick-n-easy.

Before the bar, the back end was coming around on me in the wet (right foot induced), so I will have new wheels & tires before I drive in the rain again.

[AZhitman]

2 words, Todd:

GO WIDE.

I'm searching for an "a" bar for my Q as we speak....

[landtodd]

Half the fun may be in the finding, but if you're "going wide," there's always Scottsdale . . .

[AZhitman]

True - but I meant WIDE as in tire sizes....

I hate to think of spending the $250 on the bar... Cheap basturd that I am...

[greg_atlanta]

the hard [24-Pappy Bear bar] or the soft {20-Momma Bear bar}......

I like my Pappy Bear bar!!! Wish it were bigger.

I am getting increasingly annoyed by road trips, esp. on I-85 going from Atlanta though SC, NC, etc. I'm sure the sway bar is contributing to that annoyance since there's less float in the rear to smooth out the undulations.

But any car is only as good as the roads it drives on. I'm just tired of road trips to begin with.

[Q45tech]

With the 24 mm bar before the lowering springs but with Tokico Blue all around a roundtrip from Atlanta to Durham/Chapel Hill and back would rub the skin off my left elbow and remove any feeling in my body for 3 hours after I got home.This was on some of the better roads in SC and NC!

Just can't believe any one could stand the 24mm.

[911/Q45]

I be liking my little HICAS bar I think!

[Q45tech]

I tried everything with the 24 mm bar multiple rubber bushings etc to replace the urethane but it was tricky trying to DECOUPLE the bar for FIRST 1" of wheel movement the fast progressively get it to engage..............it always felt wrong.

And the Tokico blues are not stiff enough in rebound to control a bar that is as stiff as the springs so very underdamped in rapid transition!.......by the time the Tokico Blues are subjected to double the expected stress their life is diminished to 25-30k max vs 50-55k with springs and smaller 20mm bar.

Remember the shock absorbes all the springs energy and a sway bar is a spring!

If you think about it 20% stiffer rear springs and a bar which adds up to 10- 33% more stiffness match a 20-25% stiffer rebounding shock pretty well........far from perfectly but better than a 100% stiffer [24mm] bar.

I'm not sure that many 15.9mm [Q45t] rear bars are actually doing anything as everyone I see has the old worn out bushings......but this goes well with the old worn out shocks.

Remember 20% stiffer springs and a 33% stiiffer than no bar/bar] nets a 50% increase in maxim possible rear stiffness increase [remember the springs are progressive] so it really varies from 15%-20% to say 45% so the shocks are normally perfectly matched for the highway when nothing more than +-1" sway/ bumps are the norm.............see why they call it a matched set...20%=20%.

Took me 4 years to fully understand all the parameters of this!

[landtodd]

Does anyone know the Energy Suspension part numbers for the rear end-link bushings?

[DAEDALUS]

I've asked them, and they told me that they do not make parts for the Q. I think they do, they just don't know it. I recently placed an order with Scottsdale Nissan for a load of 300ZX rear susp. parts for my friend's car, including the bushings. I will let you know how they compare to the Q's, and if they appear identical, then I would think it safe to order 300ZX bushings.

[DenverQ]

I finally got around to installing the new rear sway bar bushings and WOW!!!!!!!!! I cant believe i drove the car for so long with them like they were. With the new bushings the car is firmer and the body roll is greatly reduced. Only problem my torque wrench doesnt go down to 8.7ft llbs so i had to eye ball it, but otherwise its a great improvement now everysingle peice of rubber in the suspesion has less then 6k on it =)

Now do i really want the the 20mm bar? hmmmmmmm

junk yard will sell me one for 75 all i need is the bushings for the bar itself

now if i could only figure out my camber problem

[Q45tech]

Why is it so hard for members to believe that every piece of rubber needs replacing every 7 years or 100k. Try just sitting a set of tires out for 7 years ---- look at the sidewalls! ROT!

You can't wish the problems away!

That $75 plus new support rubber inserts from the dealer will be the best $100 you could spent on a Q as going from 12# of extra rear stiffness to 40# is 20% more total and no railroad/bad road elbow.

[DenverQ]

I think I am going to have to call the junk yard today.

The endlinks and the endlink bushings are the same right?

It was cool to drift around the corner this Morning!:ylsuper

[greg_atlanta]

I might have to boost my tires up to 38 psi to get a drift going.

Currently at 32 psi with 24mm bar (urethane bushings).

Soooo much easier to drift when your tires are overinflated!

[Q45tech]

Sure the lateral contact patch gets smaller as you overinflate so the car oversteers more [understeers less].

When you use really big rear bars almost everyone goes for much wider rear tires than front to compensate..........but that would decrease the drift since most non drifters don't won't to go off the road rear first............ever spun a Q around 3 times on on wet road and head back in the opposite direction.....the populace scatters.

[landtodd]

I might have to boost my tires up to 38 psi to get a drift going.

Currently at 32 psi with 24mm bar (urethane bushings).

Soooo much easier to drift when your tires are overinflated!

Hi Greg,

Where did you get your urethane?

[greg_atlanta]

I got the used 24mm bar and bushings off another car (T-3 owner whose totalled car was in the shop getting stripped down the same day my car was in for service).