97-98 Q 45 rear stabilizer bar upgrade

[Q45tech]

The end links have stops and precise thread lengths so that the bar cannot be over tightened. The top and bottom nuts only go so far. The only way to cheat is to use a metal washer between the bottom [and top if you desire] nut and the bushing metal retainer to get the equivalent of 1-2 more turns to compress the bushing.

I use rubber because uretane is not compressible thus no potential for adjustment if you guess wrong.

People think that OEM suspension stiffness varies between cars/brands but not very much [assumming close weights +-200 pounds]. A lux car might be 10% softer than an average car and a performance car might be +10% stiffer.

The trade off between using just rear springs and adding expensive sway bars is a fairly recent phenomena on average cars.

The old 90-96Q at 123 lb/in REAR roll stiffness compared to the Q45t with 135 lb/in compared to a [20mm A bar] at 163 lb/in is a good bit of rear stiffness change like 33% but the oem build it safety understeer was excessive in the base car.......but the front with 146lb/in springs and big front bar only need 192 pound /in* to be at the neutral point [54% front roll stiffnes vs 46% rear.

* so 192 -146= 46 lb/in obviously: the front 29 mm bar [around 175 lb/in] is stiffer than the rear 20mm [40 lb/in] bar..........but the front bar is sloppy coupled so nothing happens with the bar thru the 1 inch and little till the suspension rolls 1.5-2.0 inches.

So the car feels better with maybe neutral tiny understeer at low turn rates still progressing to understeer and more understeer as the turn gets tighter.

Even a 24 mm rear bar [ 120#] cannot over come a 175 # front bar.

The only question marks is the condition of the front bar bushings.

The 97 and later have the bar more directly coupled to the strut so there is much less rubber slop but the bar is weaker and less progressive in coupling thanks to the front isolation subframe to isolate road harshness.

Changing the 97 rear bar beyond any factory optional size should be done carefully..........Warning Eibach rear lowering springs are progressive so a sudden increase in rear stiffness is a danger in more than 2" rear body rolls sudden snap over steer with a really big rear bar and these springs.

[airman]

>Even a 24 mm rear bar [ 120#] cannot over come a 175 # front bar.

So I'm assuming 24mm on 97 q45t is still pretty much safe after all

[Chrisfrend]

The 24 mm. rear stabilizer bar (which is the stock non-t size) I had installed on my 1997 Q45t 8 or 9 months ago has greatly improved the handling of my car under all driving conditions I have encountered. The understeer has gone from fairly extreme to merely heavy. Excessive body roll, dive, and yaw are virtually eliminated. The bar is much, much stiffer than the 18mm. bar that comes stock on the 1997 and 1998 t models. I untightened the nuts on the bushings because the suspension was so firm it would make the CD player skip when I drove it over a certain bump in urban driving; now the ride is taut but not harsh. The car feels smaller and handling is much sharper. I finally decided the 24 mm. bar would be safe because it is the standard bar on the non-t model -- and with the firmer rear springs on the t probably wouldn't make that much difference in terms of safety. I found the mushy suspension was much more disconcerting, and think that Nissan made a mistake in fitting the 97-98t model with a much weaker stabilizer bar than on the standard model.

[airman]

The bar is much, much stiffer than the 18mm. bar that comes stock on the 1997 and 1998 t models. I untightened the nuts on the bushings because the suspension was so firm it would make the CD player skip when I drove it over a certain bump in urban driving; now the ride is taut but not harsh.

Thanks Chris. How old are shocks on your Q? I'm going to put new shocks (mine has 114K) and affraid if this would already be enough even without thicker bar. I don't want to make it too stiff to compromise the comfort.

[Q45tech]

One way to look at is is the ratio of springs should be 54/46 and so should the bars if neutrality is desired..................just be careful in the wet and cold weather when tire friction changes.

You MUST correct the bars rear stiffness to compensate for friction sharing when doing any acceleration or braking........why half the number [ratio] is usually safer............having the front bar 66% and rear one 33% of total bar stiffness.........146 vs 70 rear.

Glad you learned to soften rear bar by adjusting the rubber slack.

Even on the 90-96Q I have always wanted a 22-23 mm [60-80 lb/in] rear bar as years of calculations say this is correct for the entire car range 90-01Q. Nissan rarely [except active versions] changes spring stiffness because the are derived as function of body weight on a lux car.

If you try to compare the 90-96 vs 97-01 rear bars you will see they are an inch narrower in width and more convoluted [less stiff] with a different angle on the arm lengths thus 24 mm on a 97 is not nearly as stiff as 24 mm on a 90-96............the 18mm: 97Q rear bar is more like the 15.9mm rear bar on 90-95 t.

At least the 97-01 have a viable mod with Eibachs and bars.......somebody should try Pilot Sports to see what's possible in the skid pad and slalom.

[Chrisfrend]

airman, I have a used 97 and assume the shocks are original -- my car has 72,000 milies on it; the shocks seem OK for now. The ride is taut but not harsh -- the Buick quality that others here have noted is gone. Even with the stiffer rear springs on the t model, I don't understand why Nissan downgraded the rear bar on its sportier model given its major negative effects on handling. The stiffer springs on the t model make the ride a little less cushy than the standard model, but the rear bar doesn't really increase this effect noticeably so long as the bushings are not torqued too much.

Q45 tech-- thanks for you posts on adjusting the tightness of the bushings -- it can make a big difference.

[Q45tech]

Everyone with more than 60k will benefit greatly from shock replacement as the NEW rebound stiffness on the opposite wheel will slow the side to side sway dramatically. The compresion takes 203 times longer for the wear to be noticable.

With 29,000 miles [23 months] on my rear Tokico Blues I am already noticing the start of the progressive downward spiral compared to brand new. The Nitogen gas pressure is starting to fall.

Years ago [70-80's] non or low gas pressure shocks use to be replaced every 30k but back then we rarely drove 10,000 miles per year.

[pito11213]

So Tech if I remeber correctly you promote the use of factory shocks in the front and blues in the back? What is the benfit of this configuration? Are the blues all around too harsh of a ride?

[Q45tech]

I have Eibach front springs [+15%] with the smaller diameter [active bar -13%] so my NET front roll couple is very close to stock standard Q. Whereas the rear with [zero varying up to [0,20,40] +60%] [[123-> 200 lb/in]] Eibach springs with the addition of almost constant +30% [[ 40lb/in]] from rear 20mm bar [tightly coupled] is a lot stiffer.

So the rear sees +32 >+95% more rear stiffness depending on roll angle.So 320/560 ~~ 57% front roll couple at limit on the ragggggggggged edge of oversteer.......not for the faint of heart or sloppy drivers in rain.

Just like the feel with the oem fronts, the stiffer rear blues with the stiffer springs wear out faster than oem fronts with less peak spring stiffness [165 vs. 200]. Contrary to what most would expect.

Before I changed [softened the front bar] I used Blues on the front for 2 cycles [120,000 miles].

Owners must tune the car to feel right TO THEM in emergency maneuvers------when you are spinning around multiple 360's on glare ice or in the rain.

[airman]

airman, I have a used 97 and assume the shocks are original -- my car has 72,000 milies on it

That's what I thought: you have worn shocks and did have worn bushings. 50% of improvement you see came from new bushings since they start working before sway bar kicks in.

I think if I install new shocks and new bushings it will already make big difference. But if I add 24mm bar it might make things too stiff, which I don't want. .... Scratching my head

[Chrisfrend]

I finally got around to replacing all the bushings related to the new larger 24 mm. stabilizer bar. The upper bushings on the connecting rod to the lower arm had not been done. All the old bushings were very hard and dried out; my car had been in Texas for 7 years, which may have made them worse.

In any event, the new bushings were more flexible than were the old, and the ride quality is significantly better as a result. As Q45tech has pointed out, new bushings do make a big difference. However, the handling is not quite as crisp as it had been, although still a huge improvement over the stock Q45t bar. The result is probably a better balance for commuting and urban driving. I may eventually tighten the bushings a bit.

I had the bushings installed at an excellent local tramsmission shop where I was also finally getting my broken speed sensor replaced. The dealer wanted over $1,000, whereas this shop did it for $620. Fortunately, my after market warranty picked up all but $100 of this repair expense. Thanks to this board, I also had the rear main seal replaced at the same time.