THEORY ON FIX 4 WOBBLE ON LOWERED AWD's
11-05-10, 08:01 AM
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THEORY ON FIX 4 WOBBLE ON LOWERED AWD's
I have a 07 GS350 AWD lowered on H-teins(supposably the mildest lowering for the awd) since day one post lowering i've had the wobble (that FINALLY everyone agrees on) that happens post lowering a lex AWD (ie. GS and IS).
Its kinda been long discused, and we now know its NOT caused by wheel balance, poor instalation of springs, etc....One possibility is the front drive shaft (awd only), like other menbers also think its the culprit, bc lowered RWD dont get the wobble (awd and rwd have the same rear drivetrain) soo its gotta be the front part of the drivetrain.
SOO, k, heres my theory, post mult align. i noticed that our caster gets increased (usually a good thing) but MAYBE lex AWD's dont like this
, if u look at IS rwd and GS rwd, their stock caster is way more positive then the AWD's. from around 7 to 8, when the awd's are more like 4 to 5 range.
U could say the reason for the "milder caster" is because lexus wants their awd car to be less aggressive due to their possible inclement weather use, BUT, a big BUT
, maybe the reason is because the AWD drive setup dosent like very positive caster causing it to have the vibration issue, so lexus MAYBE just decided to decrease caster to remedy the prob. (positive caster cause a shift in front drive shaft angle)....since we lowered ours, that increased the caster, thus POSSIBLY causing the vibration (if u put the stock springs back and thus increasing the ride height, the vibration goes away).
My caster is at +5.4 bilateraly kinda at the max for gs awd specs, the stock setting is at +4.9 (middle), i know thats not much of a diff. but maybe thats the cause, if ur lowered w more aggressive springs, in assuming ur caster is even greater...NOW, since lexus has a caster bracket set replacement +/-20 minutes, which is about +/-.33degrees, im wondering on a not TOO lowered gs awd if installing the -20 ones on both sides, thus decreasing caster to near stock angles will this improve the wobble????????
Its kinda been long discused, and we now know its NOT caused by wheel balance, poor instalation of springs, etc....One possibility is the front drive shaft (awd only), like other menbers also think its the culprit, bc lowered RWD dont get the wobble (awd and rwd have the same rear drivetrain) soo its gotta be the front part of the drivetrain.
SOO, k, heres my theory, post mult align. i noticed that our caster gets increased (usually a good thing) but MAYBE lex AWD's dont like this
, if u look at IS rwd and GS rwd, their stock caster is way more positive then the AWD's. from around 7 to 8, when the awd's are more like 4 to 5 range. U could say the reason for the "milder caster" is because lexus wants their awd car to be less aggressive due to their possible inclement weather use, BUT, a big BUT
, maybe the reason is because the AWD drive setup dosent like very positive caster causing it to have the vibration issue, so lexus MAYBE just decided to decrease caster to remedy the prob. (positive caster cause a shift in front drive shaft angle)....since we lowered ours, that increased the caster, thus POSSIBLY causing the vibration (if u put the stock springs back and thus increasing the ride height, the vibration goes away).My caster is at +5.4 bilateraly kinda at the max for gs awd specs, the stock setting is at +4.9 (middle), i know thats not much of a diff. but maybe thats the cause, if ur lowered w more aggressive springs, in assuming ur caster is even greater...NOW, since lexus has a caster bracket set replacement +/-20 minutes, which is about +/-.33degrees, im wondering on a not TOO lowered gs awd if installing the -20 ones on both sides, thus decreasing caster to near stock angles will this improve the wobble????????
Last edited by derfp2; 11-05-10 at 10:27 AM.
huh
11-05-10, 10:15 AM
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