poly anti- sway bar bushings-anybody using them?
poly anti- sway bar bushings-anybody using them?
Is anyone using or have any input on the whiteline poly (or other brand) anti-sway bar bushings? My suspension is basically stock; stock springs and anti-sway bars, new OEM TC rods/bushings, new sway bar end links, KYB GR2's. Not trying to make a road racer, just slightly enhance the factory suspension set-up a bit. I may later add poly TC bushings and poly LCA bushings. Thanks, Bill
I have them, of course, my poly bushings came with my suspension techniques bars...
If you arent going to modify your sway bars(IE go stiffer/larger) poly end links and bushings would help out a bit in controlling body roll....
I would reccomend getting them if you dont plan on upgrading the sway bars themselves.-chet
If you arent going to modify your sway bars(IE go stiffer/larger) poly end links and bushings would help out a bit in controlling body roll....
I would reccomend getting them if you dont plan on upgrading the sway bars themselves.-chet
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Q45tech
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- 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
On Nissan rear design, you have double end links with 4 bushings each and the center supports.
Not unusal to see a tapered up slack of 1/8" x 4= 1/2" [in each direction] when this is multiplied by the end link coupling point [middle of lower a arm] divides by 4 ......so 2" of body roll before the bar is 100% coupled.
There is some action of the rear bar but probably less than half during the 2" roll and nothing [very little] in the 1st inch of body roll.
A 20 mm bar would be expected [calculated] to resist roll by 40x3"=120 pounds in a 3" sway..........but probably only provides 60 pounds due to rubber bushing compression [depending on bushing age and tightness]. By factory design to reduce road vibration thru bar to opposite wheel.
Solid urethane/nylon/prothane still has some small give, maybe 10% vs 50% for rubber................120x 0.9= 108 vs 60 oem bushings.
Roughly the same as increasing bar diameter from 20>...22.5-23.0mm.
Many cars like early BMW had weak attachment points for bars and end links. Things would bend/break with stiffer bars or urethane.......however the Nissan/Q/J rear points are very strong [compared] but sometimes the oem end link rod needs to be upgraded..........try the oem if you bend it the answer is obvious. Usaully only greater than 23 mm hollow rear bar will bend it but solid rear bars might if coupled tight enough.
Don't go rock climbing with urethane bushings.
Not unusal to see a tapered up slack of 1/8" x 4= 1/2" [in each direction] when this is multiplied by the end link coupling point [middle of lower a arm] divides by 4 ......so 2" of body roll before the bar is 100% coupled.
There is some action of the rear bar but probably less than half during the 2" roll and nothing [very little] in the 1st inch of body roll.
A 20 mm bar would be expected [calculated] to resist roll by 40x3"=120 pounds in a 3" sway..........but probably only provides 60 pounds due to rubber bushing compression [depending on bushing age and tightness]. By factory design to reduce road vibration thru bar to opposite wheel.
Solid urethane/nylon/prothane still has some small give, maybe 10% vs 50% for rubber................120x 0.9= 108 vs 60 oem bushings.
Roughly the same as increasing bar diameter from 20>...22.5-23.0mm.
Many cars like early BMW had weak attachment points for bars and end links. Things would bend/break with stiffer bars or urethane.......however the Nissan/Q/J rear points are very strong [compared] but sometimes the oem end link rod needs to be upgraded..........try the oem if you bend it the answer is obvious. Usaully only greater than 23 mm hollow rear bar will bend it but solid rear bars might if coupled tight enough.
Don't go rock climbing with urethane bushings.
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Touring240
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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
Sway bars are not really meant to totally control body sway. They are there to tune the ratio of front to rear roll couple stiffness.
If you double the total spring/bar stiffness [as applied to the wheel] you will only cut the sway in half! So don't think that adding a 20mm rear bar [40lb/in at best] on 123 lb inch springs will do much sway reduction 123/163= 25% or roughly 3/4 of an inch at best! You would need a 25mm rear bar to half the body roll [sway]...........and the car would oversteer in wet to the point of dangerous to drive.
Factory designs are meant for average owners thus 3.5-4" of body sway is ideal to make the ride comfotable on bumpy roads.
Something like +- 2 inches would be acceptable when ride didn't matter vs say +-1" in a full race car where the driver only has to last a few hours before hospitalization to recover.
The limit for sway bar stiffness is that the bar should be no more than 50% or total axle end stiffness at the max sway [body roll].........Something like 33-40% is more tolerable on street...........because it is impossible to add shocks that just compensate for the bar changing stiffness.......thus the springs will be controlled but the bar will oscillate in certain situations.....rapid lane changes.
If you double the total spring/bar stiffness [as applied to the wheel] you will only cut the sway in half! So don't think that adding a 20mm rear bar [40lb/in at best] on 123 lb inch springs will do much sway reduction 123/163= 25% or roughly 3/4 of an inch at best! You would need a 25mm rear bar to half the body roll [sway]...........and the car would oversteer in wet to the point of dangerous to drive.
Factory designs are meant for average owners thus 3.5-4" of body sway is ideal to make the ride comfotable on bumpy roads.
Something like +- 2 inches would be acceptable when ride didn't matter vs say +-1" in a full race car where the driver only has to last a few hours before hospitalization to recover.
The limit for sway bar stiffness is that the bar should be no more than 50% or total axle end stiffness at the max sway [body roll].........Something like 33-40% is more tolerable on street...........because it is impossible to add shocks that just compensate for the bar changing stiffness.......thus the springs will be controlled but the bar will oscillate in certain situations.....rapid lane changes.