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Fast Friday #10: Suspension

How to go faster, stop quicker, and turn harder. Chips, exhaust, larger turbos, bigger/slotted/drilled rotors, high performance brake pads, manual boost controllers, performance shocks/struts/springs, airbox mods and more! Also discussion on HID and Xenon lights, aftermarket foglights and other exterior lighting.
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matthew1
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Volvo Repair Database Fast Friday #10: Suspension

Post by matthew1 » Fri Sep 14, 2012 4:19 pm

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Suspension Setup and Tuning

Always The Bridesmaid, Never The Bride
Suspension doesn’t get as much attention as it should in my opinion. Typically the conversation includes what brand lowering springs are getting installed, what size sway bar, and what brand of shocks with too little attention to how it all works together. So let’s take some time to cover the various aspects of suspension and how you can better select the parts you need to get your setup just right!

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Springs
Springs support the weight of the car and are generally specified in pounds of force required to deflect (compress) the spring 1 inch, also known as spring rate. The higher the number the firmer/stiffer the spring. Springs that take a linear amount of force to deflect are called linear springs while progressive springs take less force to deflect initially and take more force to continue deflection as the spring is compressed. Progressive springs are popular with performance enthusiasts as they provide a more comfortable initial spring rate with a firmer final spring rate that keeps the vehicle more stable. A good way to think about springs is to remember that they limit how far the suspension moves, not how fast.

Shocks/Struts
Whether you call it a shock, strut, or a damper the purpose of shocks is to slow down the vehicle suspension movement to absorb energy over time and make the ride more comfortable while also preventing the spring from ‘bouncing’ the wheel and tire off the ground after a bump or impact. Shocks dampen this energy both on the upward stroke (compression) and the downward stroke (rebound). Adjustable shocks that you find typically in the aftermarket will have rebound adjustment and higher end units will also have compression adjustment as well. The more stiff/firm the shock the shorter period of time it will dampen the suspension energy and the rougher the ride. A good way to think about shocks is to remember that they limit how fast the suspension moves.

A big mistake a lot of folks can make is thinking that the firmer the shock/spring combination the better. This is certainly not true as a setup that is too firm does not give enough feedback to the average driver to allow for them to feel and experience the edge of traction without going over it unaware. A car that is too ‘tight’ creates a fine line of traction that once crossed can be dangerous.

Sway bars
Sway bars limit the roll of the car by distributing the vehicle weight from left to right as well as the balance from front to rear. As with springs and shocks too stiff can be a problem and it’s important to remember that stiffer springs will affect the roll couple distribution as well so they become additive to effect of a sway bar. Most sway bars also can be ‘tuned’ to provide more oversteer or understeer by changing the mounting location on the end of each moment arm. Most manufacturers design quite a bit of understeer to keep the vehicle from ‘fish tailing’ which would likely scare the average driver and render the car as being branded unsafe. Understeer occurs when the wheels are turned but the vehicle does not follow the direction the wheels are pointing. Oversteer is the opposite, where the wheels are pointing in a direction but the rear of the car has lost traction and is not following the path of the front wheels. D1 drift drivers use oversteer to create excessive entry angles into corners to create entertaining driving.

Bushings
Polyurethane suspension bushings are a popular upgrade and provide enhanced suspension dynamics by reducing the reaction time of the suspension when compared to driver inputs from the steering wheel. These type of bushings transfer the suspension energy more quickly which results in a more nimble vehicle and crisper steering and chassis feedback. For most newer cars the isolation of the chassis to the suspension is so well designed that when firmer bushings are installed the impact to driver comfort with regard to noise, vibration, and harshness is minimal.

Fast Fridays are for you, so let us know what’s on your mind!

Robert Lucky Arnold
ARDtuning.com

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1997 850 T5, MSD ignition coil, Hallman manual boost controller, injectors, R bumper, OMP strut brace [gone]
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Vinhawk
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Re: Fast Friday #10: Suspension

Post by Vinhawk » Sat Sep 15, 2012 1:52 pm

This has been my nightmare going on 3 yrs now. Every 6-8 months I'm changing my control arm bushings. I have a 2001 Volvo V70 T5 that I had upgraded the anti sway bars from ipd back in july of 2008. A few months later I changed the front struts to OEM. I have never lowered the car. Everything was great and I looked forward to trips to the mountains. Now for the nightmare... About a year and a half into to changing the anti-sway bar in the front, I start having the soft spungy feeling in the front end. Control arm bushings!!! Completely blown out. No prob, I order them up from ipd and change them out myself (bloody knuckles and all). 3 months later Left one goes out (not just spungy but metal to metal). I call up ipd they send me out a new one and I have my mechanic put it on this time. 3 months later, Right one goes out, same thing, metal to metal...on and on and on. I've changed out control arms 4 times now and due for new ones again, something ain't right...Any suggestions? FYI car has never been in an accident.



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Re: Fast Friday #10: Suspension

Post by ARD-Lucky » Mon Sep 17, 2012 8:06 pm

Given your experience it's hard to say... environment (temperature) and corrosive chemicals that may be used in your area could contribute to premature failure. I honestly have found many OE parts to be sub par for longevity partly due to over use (IMO) of recycled materials. So perhaps a poly bushing replacement might be well suited for you.



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Re: Fast Friday #10: Suspension

Post by kcjones » Thu Sep 20, 2012 7:43 am

This is probably what you need.

http://www.ipdusa.com/products/8755/115 ... -2001-2007

They're on sale until the 23rd. They have a Youtube video about them if you're interested.



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kcodyjr
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Re: Fast Friday #10: Suspension

Post by kcodyjr » Thu Sep 20, 2012 2:40 pm

Can poly suspension bushings be installed to 850's with their one-piece control arms? Is it necessary to retrofit the early 1993 alloy arms?


1997 850 GLT sedan, 152K and WHOOHOO!
RIP 1996 850 wagon, 201K, hit by a runaway 4-wheeler
RIP 1996 850 GLT sedan 5spd, 260K, rearended someone
RIP 1986 245 boring, 200K, rusted beyond inspectability
RIP 1981 242 turbo 5spd, 300K, serious teenage crash

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Re: Fast Friday #10: Suspension

Post by Vinhawk » Wed Sep 26, 2012 8:59 pm

Thanks for your reply. They've been replaced with HD control arms already. I starting to strongly think that the IPD anti-sway bar is not intended for a daily driver in SoCal road conditions.



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