Tech.. sway bar tightening techniques?

[elwesso]

Q45t, 28mm front, 20mm rear...

IM having a HELL of a time trying to get this sway bar tightened right.. I remembre some posts saying that it is a chore to get them right, and to keep it right and you are correct!!!

I tried to tweak it a little bit this afternoon, as it was a little oversteer prone, so i turned the front like like maybe 1 turn (approx 1 thread) and now its slightly understeer prone...

Im running OEM bushigns, but will eventually run poly because id like it to be a little tighter, even if that does compromise ride.. Id like that extra responsiveness.....

What im asking is, do you have a standard with new OEM bushigns on tightening it.. Obviously its not very efficient to go out and just keep experimenting until you get it right.. I would assume you have some sort of standard that you start with and then tweak from there.....

The turn in on this car is a little vague, and i would assume thats from HICAS... its not as responsive as id like it.. not sure if HICAS is causing more or less oversteer... im thinking ill just remove the HICAS fuse unless it really does something on the Q45..... MOst Z32 guys dont like HICAS and get eliminators..

I feel like im asking a newbie sort of question but id appreciate any help thta anyone could give..... I demand perfection and this 20mm active bar makes it very close, now it just needs tweaked... I think using the poly bushings will help eliminate any difference with the rubber and should help keep things as consistent as possible.....

[Q45tech]

Just tighten the rear up, then fine tune with front.

Remember the front bar is 3 times stiffer than the rear bar even with 28 mm so you need very little front tightness or you understeer severely.......especially with oem 95 load index front tires. Q needs bigger/stronger front tires [more air space].........big old MB/BMW use to use 100-104 load index to get the front under control. Why the 235/60/15 [98H] feels so good.....the extra 8% reserve strength tighten up [reduces slip angles] the steering even with soft sidewalls.

Surely don't want urethane front bushings with such a stiff front bar as with only 2 front end link bushing per side vs rear 's 4.

[maxnix]

Surely don't want urethane front bushings with such a stiff front bar as with only 2 front end link bushing per side vs rear 's 4.

Yeah, members keep missing that in search of the holy polyurethane grail.

Thought you diparaged polyurethane on the rear end links too because lack of compliance damaged links permanently.

On a side note, the NISMO polyurethane tension bushings aren't nearly as intrusive on TX roads. It seems to be affected by the resonance of the system also, and not just the compliance. The resonance is a lower frequency with the OEM silicon filled bushings.

[elwesso]

Just tighten the rear up, then fine tune with front.

Remember the front bar is 3 times stiffer than the rear bar even with 28 mm so you need very little front tightness or you understeer severely.......especially with oem 95 load index front tires. Q needs bigger/stronger front tires [more air space].........big old MB/BMW use to use 100-104 load index to get the front under control. Why the 235/60/15 [98H] feels so good.....the extra 8% reserve strength tighten up [reduces slip angles] the steering even with soft sidewalls.

Surely don't want urethane front bushings with such a stiff front bar as with only 2 front end link bushing per side vs rear 's 4.

OK thanks.. That helps, ill just tighten the rear up all the way (or a lotof the way) and then fine tune the front..

[maxnix]

The main thing is to use a torque wrench so there is some accurate calibration.

[Falkdesigns]

Yeah, this is the first time (besides Wes chatting w/ me about it) that I've ever seen how tightening the sway bar brackets has any effect on handling. Basically in all my years, it goes:

endlinks, XX lb/ftd brackets, XX lb/ftcontrol arms, XX lb/ft

and that's it. How can tightening the bolts change anything (I'm open to learning something new here) when the bushings, etc stay the same. As far as I know, each bolt will have a set torque and it has nothing to do with handling effect, and everything to do with keeping the bolts on. D brackets might have a 18 lb/ft, end links a 24 lb/ft and the bolts to the control arms a 40 lb/ft rate, or something along those lines. Overtightening ANY of them can cause them to strip/snap, and undertightening can (will) cause them to fall out.

What am I missing here?

[DAEDALUS]

You're missing the effect that the tightening has on the preload of the bushing. The more preload, the less body roll before the bar starts doing work.

[maxnix]

Basically, one is limiting the amount of deflection in the rubber components. And of course there is a range for the torque values, but slight varinaces can be signifincant. I have noticed the most sensitivity on the rear links with the a bar on the G50.

[Falkdesigns]

I'm really suprised that you can vary the mounting brackets torque as too little will have it fall off. The way I see it, if the D brackets are metal to metal flush, as long as they are the correct torque, it would be all there is. I can see the concept of the preload on the bar (although I find it hard to believe it has much effect). What do you guys use to lube the bars? I've always used Teflon tape, and have upgraded to aftermarket bars on other cars I've owned, but they always had set torque amounts. Some of the bars were true adjustable bars, with several holes to choose for mounting the endlinks (closer in = stiffer, farther out = softer).

Thanks for the explanation. Does the same go for the Y33? When I looked around, it appears to be mounted basically the same as any sway bar.

[maxnix]

Does the same go for the Y33? When I looked around, it appears to be mounted basically the same as any sway bar.

Study the end links and see how much trigonometry you can recall.

Rear suspension the same multilink design on most RWD Nissans.

[elwesso]

The thing you cant do with torque is that you arent tightening them down all the way (at least in theory)... When you tighten it down more, the bushing is already compressed more and thus has less time where the sway bar doesnt do anything (slop)

I suppose with poly bushings you would just tigten them down all the way but with regular ones you dont do that... Since your using a nut and washer to hold the end link to the control arm and sway bar its not going to fall off..

I wish nissan used a thing that just threaded into the control arm, so there wouldnt be this much room for error... however, its very easy to adjust and neutral handling is very easy to get.....

[Q45tech]

Notice the 97 and later fronts have bars which attach to the shock tube.Even though the bar looks gigantic the right angle arm is more than twice as long so the bar ACTS 1/3-4/10ths as stiff.............but little compliance thus the need for the front subframe to isolate first inch bump road shock.

Members forget that the extra washers in the rear give you adjustablity vs the oem setup where the treads bottom at the correct initial set up so you can't over tighten and deform bushings.

[elwesso]

Notice the 97 and later fronts have bars which attach to the shock tube.Even though the bar looks gigantic the right angle arm is more than twice as long so the bar ACTS 1/3-4/10ths as stiff.............but little compliance thus the need for the front subframe to isolate first inch bump road shock.

Members forget that the extra washers in the rear give you adjustablity vs the oem setup where the treads bottom at the correct initial set up so you can't over tighten and deform bushings.

I was not aware of this.. For the rear you are supposed to just tighten it down all the way... and then go from there by tweaking the front....

To me it seems like the best thing to do is to get poly rear bushings to get things as firm as possible, or maybe a half poly half rubber deal... I dont know, theres so mayn things to do it seems just easier to get stock bushings and just get it close... Eventually ill have to go and do some testing in a parking lot and then keep tweaking... get it just how i want, and then we can post up how i tightened them donw.. IE how many threads exposed, etc.....

Ill have ot go get some more sway bar washers...

[John Nordling]

I have a 90 Q45t with the Hicas and new OEM bushings, so this thread really interests me as well. But, what about Q45 Tech's comments on the tires? I don't know how to frame his response, but here it is:

"Remember the front bar is 3 times stiffer than the rear bar even with 28 mm so you need very little front tightness or you understeer severely.......especially with oem 95 load index front tires. Q needs bigger/stronger front tires [more air space].........big old MB/BMW use to use 100-104 load index to get the front under control. Why the 235/60/15 [98H] feels so good.....the extra 8% reserve strength tighten up [reduces slip angles] the steering even with soft sidewalls."

If the tires will do the trick, what choices do I have in VR rated tires in this size? I have been doing research and can't find anything that works well in the wet.

Thanks for your help...............John in Seattle

[maxnix]

If the tires will do the trick, what choices do I have in VR rated tires in this size? I have been doing research and can't find anything that works well in the wet.

Thanks for your help...............John in Seattle

Well, since the Firestone SZ50 EP went off the market, there is not much.

I ran 225/60-15 Yokohama AVS dB (non S2) for 30K in Seattle, and was very pleased with their performance, especially in the wet. Now, the new 235/60-15 Michelin XGTH seem to be very good since the tread is still deep. The size is perfect and the 98 load rating helps a lot. Eventually, will have to step up to 17" or probably 18" rims and bigger brakes to get available speed rated tires capable of serving on the G50. Mucho bucks to get wheels as strong as BBS forged on the t model.

[elwesso]

John, its almost more economical to upgrade to the Y33 16s then you can get some BEEFY tires!

[John Nordling]

I may just have to settle for the stock tire size to get the VR rating. Really can't afford rims AND tires now after just spending about $6,000 on repairs. Now I'll just be quiet and see how to set up my sway bars.

John in Seattle.

[Q45tech]

Had to tighten my front bar end link nut up 1/2 turn per side yesterday to fix a vague feeling [more understeer/neutral when trunk loaded 120 pounds] that had been growing for the last 4,000 miles.

That [ 2 x 1/2 turn] was too much [but it will wear in]...........then again maybe it was the fact that it was last done in Feburary [cold vs warm now] 30F change.

The point is how sensitive the set up is on the front.........with just one washer [0.18"] per side to allow adjustablity.

Also newish front shocks [14,000 miles] vs old rears at 44,000. [starting to feel the wear out point coming [~~60k].......or so it has been for the last 4 sets of shocks [50k, 120k, 180k, 240k rears].Will I buy another set [300k] or will the car get retired?

What happens when you get the suspension nearly the way you want it, every little wear thing becomes noticeable.........especially when you drive the same route everyday.

Then again NASCAR drivers say they can feel a 1.0 psi tire pressure change.

Must drive them crazy from lap 1 to lap 20.

By the way the current front 235/60/15 just passed 40,100 miles, [ordered new ones] the value of 3-4k rotation and flipping on wheels at 10k intervals.......still extremely low balance weights. [less than 12 grams per side].........considering the extra stress that the tightened suspension adds..........I'm always impressed with Michelin...........we see them down to metal showing on inside edges [Q camber] and the tires keep on trucking [few blow outs] thanks to the expensive butyl halogen rubber interior safety ply to seal in air.

Those [experiment] Kumho KH11 [225/60/15] gave up the ghost at 8300 miles and have been sitting [resting] since December......they couldn't even handle service as rear tires.

Happened to check a newish set of DB2 on a Q they were extremely heel/toe feathered as occurs with all directionals.

Just pointing out that few front tires can take the weight stress a Q creates when the suspension is on target.

[maxnix]

Also newish front shocks [14,000 miles] vs old rears at 44,000. [starting to feel the wear out point coming [~~60k].......or so it has been for the last 4 sets of shocks [50k, 120k, 180k, 240k rears].Will I buy another set [300k] or will the car get retired?.....

By the way the current front 235/60/15 just passed 40,100 miles, [ordered new ones] the value of 3-4k rotation and flipping on wheels at 10k intervals.......still extremely low balance weights. [less than 12 grams per side].........considering the extra stress that the tightened suspension adds..........I'm always impressed with Michelin...........we see them down to metal showing on inside edges [Q camber] and the tires keep on trucking [few blow outs] thanks to the expensive butyl halogen rubber interior safety ply to seal in air.

Those [experiment] Kumho KH11 [225/60/15] gave up the ghost at 8300 miles and have been sitting [resting] since December......they couldn't even handle service as rear tires.

Happened to check a newish set of DB2 on a Q they were extremely heel/toe feathered as occurs with all directionals.

Oh god, you will faint when you see the price of OEM front struts - now $183 each from Joe. I prefer the Tokico blues anyway, but I am not trying to balance to a fine degree like you are.

Looks like I will be stuck with my XGTH longer than I expected, unless the traditional wet traction problems appear at 50% tread wear. Last XGTH (several years ago on another car) I ran to inside steel was starting to show also. Embarassing, but they worked great.

Kumho experiment does not surprise me as one generally gets in quality as to what one pays in price. Notice most owners who like these tires are in much lighter cars. Then again, maybe the heavier car driveres just can't tell.

Ran my AVS dB (non S2) for 30K with no feathering. Flipping and a tight as OEM new suspension mandatory for good wear and handling. Then again, I drive it like the two ton luxury sedan it is, and not like a Miata.