The Steering and Suspension Thread

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cleantune
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The Steering and Suspension Thread

Post by cleantune »

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Hi everyone, I realized there is a bulk of material dedicated to power on here, but (and please correct me if I'm wrong), I have not come across a thread dedicated to just steering and suspension. I saw a previous thread on here about a steering problem and I'm sure there are other threads on here with similar topics. This may be a great spot to share some info that may help serve as a reference for any future steering or suspension dilemmas/ problems (I currently have some myself).

Just trying this out.... think kind of like the "show your engine bay" thread, but for sharing steering and suspension pics, info, suspension settings, suspension tech, steering tech, alignments, etc- everything suspension and steering related; can be anything. I know some other forums have similar threads, but it would be good to add some more variety of first-hand experiences to the mix.

Lemme know what you girls and guys think :)

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Re: The Steering and Suspension Thread

Post by supakat »

That would be cool. Setup for drag, auto x, drift....
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Re: The Steering and Suspension Thread

Post by cleantune »

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yes, exactly! all those categories would be a part of the discussion. One would be able to go through this thread and figure out a "starting point" or just ideas for their own setup, based on the info on here, contributed by other members- both "text book" info and experience.

If we could get a few more fellow members on board (just a reply, could be a simple "yes"), I'll start putting together a "summary post(s)" (something that lists main suspension components/ concepts) and then we can get this thing going!

Again this would be anything suspension or steering, including, but not limited to geometry discussion, roll centers, alignment settings, drop knuckles, ackerman and how spacers and wheel offsets affect this, scrub radius, overcentering steering, suspension upgrades, bushings, tips, setups, pics, questions, discussion, etc. The "summary post(s)" mentioned would be general info and pics (edited into the first post) and then updated when necessary.
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Re: The Steering and Suspension Thread

Post by adamky »

I'm not smart enough too add anything useful here, but I love the idea!
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Re: The Steering and Suspension Thread

Post by cleantune »

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Yes you are! whatchu talkin bout Willis?!

Maybe one or two more bumps on interest in this thread, then we'll get this thing started?

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Re: The Steering and Suspension Thread

Post by BigLoukaT »

I'll throw one more vote of support. Based on your build thread and how well you provided your subframe/bushing rebuild and kaaz differential install, I'm sure this will be full of good info. That and the more technical threads the merrier at this point - hopefully will pull more lurkers into posting again (which I'm guilty of as well)
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Re: The Steering and Suspension Thread

Post by cleantune »

^Awesome, thanks!

So, to start, I thought we could break this thread down into suspension and steering; focusing on suspension components first, then steering, followed by alignment and other suspension geometry/tips/tricks. I’ll try to include as much as I can, but I don't know everything, I’m just sharing information I’ve read, heard and/or experienced with this stuff so if I miss something please point it out- this will be a work in progress

Had to start with this haha:

Damper:
Image

Dampener:
Image


Basic components and some variations:

Coilovers (coil over damper)
Image

The spring helps keep the height of the coilover and absorbs energy, while the damper controls how this energy is absorbed and released.

Think about if you’ve ever ridden in or have seen a car with shorter “lowering” springs and OEM dampers on the road. The ride is very stiff and bouncy. The spring and damper are not working together in this case. The added shorter/stiffer spring is making the damper more compressed at static height (stiffer) and the ride bouncy because the OEM damper has been “valved” for the OEM spring stiffness/height.

Valving:
Image
Image

The sealed body of the damper is usually filled with viscous oil and charged with Nitrogen or another inert gas. Towards the bottom of the coilover’s “piston shaft” (perhaps there is better word for this) there is a piston with passageways going through it (pics shown above). Shims in reducing size (deflecting valve shims) are stacked on either side of this piston, covering these passageways. During the dampers operation, when the damper “sees” an external force, these deflecting valve shims flex, letting fluid pass through the valves. Sometimes there are other passageways/ports that let oil through the piston as well.

So revalving? Usually just changing the shims and/or altering the aperature of the passageways/ports through the piston to achieve desired damping.

Adjustable dampers' adjustment controls both the compression and rebound stroke of the damper.
How adjustment screw works to stiffen the damping (at least on Bilstein’s dampers):
https://www.youtube.com/watch?v=GoqvSMo1PYo


External reservoirs:
-Generally work to help control the internal valves during the rebound stroke of the damper
Image

Height adjustment:
-internally threaded base allows height adjustment w/o changing stroke distance or spring preload (*not all coilovers have this)

“Twin Tube” vs “Mono tube”


Image

-refers to the damper body having one chamber or two chambers (one nested inside the other)

Twin Tube:
•street driving w/ occasional track use
•longer piston stroke (than monotube)
•smaller piston area (lower degree of tuning precision)
•the pressurized gas inside is in direct contact with the liquid, viscous oil
Image
Image

Mono Tube:
•Track specific (can be used on street)
•shorter piston stroke
•larger piston area (higher degree of tuning precision)
•the pressurized gas is separated from the liquid, viscous oil by a secondary piston that is free
floating (“free piston”)
Image
Image

*So whats the significance of the oil coming in contact with the oil vs the two components being separated inside the damper body by a free piston?

1.One major consideration is the heat created by the piston movement, which causes expansion (mainly of the gas), increasing the pressure inside the damper. While this change in damper performance may not be felt for street and occasional track use, for dedicated track cars this may be something to keep in mind. Supposedly the affect of this thermal expansion is greater with a Twin Tube design, where the gas is in contact with the oil; opposed to a monotube, where the oil and gas are separated.

2. Since gas rises, only Monotube dampers can be Inverted (I think factory Evos had this design). Inverting the damper body frees up unsprung mass, which usually translates to better handling.



(to be continued.... I'm sure the other components will not have nearly the amount info coilovers do)
Last edited by cleantune on Thu Jan 21, 2016 12:22 pm, edited 1 time in total.
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Re: The Steering and Suspension Thread

Post by Bubba »

I'm all for adding insight to suspension setups but I'm not at home to show my equipment. I'll try to add to useful input to whatever questions may come up though.
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Re: The Steering and Suspension Thread

Post by cleantune »

Bubba wrote:I'm all for adding insight to suspension setups but I'm not at home to show my equipment. I'll try to add to useful input to whatever questions may come up though.
Awesome thanks! yeah the more info the better.

----------------

Rear Suspension

Rear lower control arms (RLCA)
-some adjustable available to change track width, but axle length may need to be altered
Image
Image

Rear upper control arms (RUCA) or Camber arms
-like name says, to adjust rear camber
Image

Toe arms
- derr, to adjust toe
Image
Traction control arms (TCA)
-used to help adjust bumpsteer, by working to maintain toe alignment in rear through
that setups suspension travel
Image

*PBM or Parts Shop MAX has a cool adaptation for the joint between the toe and rear knuckles that allows for more fine tuning of bumpsteer:
>>>>>>>>>>>Video of how it works: https://vimeo.com/136145062 <<<<<<<<<<<

Image

Front Suspension and Steering

Front Lower Control Arms (FLCAs)

Tension rods, alternatively called "compression" rods when they are located in back of the FLCAs
-named this because they are in “tension” under braking conditions
-used to help adjust caster as long as the FLCA is not binding; obviously most aftermarket FLCAs or OEM knuckles modded with Shpherical/ Rose joints would allow for a much greater range of caster adjustment
Image
-parts shop max uses a two-piece design:
Image

*Some arms are combined like the one-piece design GKTECH has:
Image

Front and Rear "Sway Bars" or "Anti-roll Bars"
-When there is high suspension stress on one side of the chassis during cornering, these bars help to keep the opposite side of the cars suspension "planted" on the ground
Image
^Lets just pretend that car was a Nissan ;)
-------
Tierods (TR)
-many variations from different companies. I’ve heard stronger is not always better for these. Some people complain that when they hit something the tierod was okay, but they bent their steering rack or bent/broke another suspension compnent. Then again others say stronger is better, so I suppose it’s a personal choice
Image

Tie rod ends (TRE)
-This is usually the part that is extended to make up for the extra length of an aftermarket FLCA; Generally, the tie rod ends are the only component that needs to be altered with a longer FLCA
Image
Image
Last edited by cleantune on Thu Jan 21, 2016 3:19 pm, edited 1 time in total.
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Re: The Steering and Suspension Thread

Post by cleantune »

Drop and Function

Rear Drop Knuckles:
•Main advantage is the raised spindle/hub location, which effectively “drops” the ride height, while maintaining “normal” suspension geometry. With most chassis setups the suspension can only be lowered so much, without gaining too much camber and causing suspension arms to bind. Drop knuckles aim to keep the wheel as flat as possible on the road, while freeing up some movement/travel of the suspension links.
Image
^ the E-brake anchor hole is located on the bottom instead of the top like the OEM knuckle so the hub location could be moved upwards
Image
Image

Front Drop Knuckles:
Image
Image

alternatively the OEM knuckles have been modified to achieve similar results. GKTECH makes a bolt-on piece, which effectively raises the front hub (for the drop in height), while maintaining proper suspension geometry:
Image

• Okay, so for the front drop knuckles, same advantage as the rear drop knuckles, except now there is an opportunity to change ackerman….

Ackerman (ackerman steering)
-Most four-wheel steering chassis have ackerman steering. It prevents noisy squealing in parking lots by reducing lateral wheel dragging/pushing by keeping the wheels inline with their natural “steering arc”
Image

To better explain this, if a string was held from a given point to the middle of each front wheel, during, a right hand turn (pic above) the outside wheel (furthest from the given point) would draw a larger radius around that point than the inside wheel; therefore:
•larger radius, less angle needed for outside wheel
•smaller radius, more angle needed for inside wheel

Image

This “angle” refers to the ackerman angle of each wheel.
To change this, the angle and or distance between the front knuckle’s rear extension (where tie rod end mounts) and the central pivot point of the front knuckle (where the FLCA end mounts to) is altered.
Image

Why reduce ackerman angle?

•For circuit racing, it can help with sharper/ faster turn-in, reduce some wheel drag/ push through corners in conjunction with adjusting front toe settings to help dial-in tire "slip angle" (the lateral drag/push) depending on what the track requires.

• For drifting, the same thing, except allowing one to keep higher speeds through corners at or near full lock at the penalty of having some wheel drag/ push with less steering angle. Also, with the reduced ackerman angle it allows for more front toe adjustment/steering rack movement

Link:
http://www.longacreracing.com/Userfiles ... omenon.pdf

I've read F1 cars use Anti-ackerman steering :icon-eek:
.... so basically, picture our knuckles, but swapped sides, so that during turn-in now the outside wheel has more angle than the inside wheel! So these cars drive straight but gain a toe in condition with turn-in.

....aright, so who want to try out this anti-ackerman first? :mrgreen:

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Re: The Steering and Suspension Thread

Post by cleantune »

[reserved for more info]
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Re: The Steering and Suspension Thread

Post by Bubba »

I'm not a suspension expert but I do concentrate on understanding the different issues that I run into with my car.

I've dealt with and fixed lack of traction in the rear and front tires pushing thru corners at high speeds but I think those are fixed now.

I've got an S13 coupe with...

Fortune Auto 500 Series Coilovers
GK Tech rear drop knuckles
' ' Front Caster Arms
' ' RUCA
' ' Rear Toe
' ' Rear Traction
S14 subframe
Stance S14 SF Conversion Bushings
SPL Parts solid Diff mounts
SPL rear lockout kit
S14 Nismo F/R Lower Control Arms
Nismo S13 Powerbrace
Whiteline Swaybars F/R
Tomei 2-way Diff (track)
Shimmed J30 Diff (daily)

0* Toe all around
-3.5* Camber up front
-1* Camber in the rear

17x9's wrapped in 245/40's
BFG KDW front
Federal ss595 rear

All of my swaybar bushings are Poly for the moment. I'm switching to a J30 rear swaybar soon because they are hollow and work just as good as the Whiteline bar for what I'm aiming to accomplish. If I find poly bushings that fit it I will be using those as well. The rear Whiteline bar is just too stuff for my style of driving. I have never had an issue getting the rear end out regardless of what rear swaybar I use so I'm opting for the lighter weight and more grippy option while I'm making changes.
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Re: The Steering and Suspension Thread

Post by cleantune »

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Bubba, nice setup. Hey, how do you like those GKTech rear drop knuckles? I've heard good things about them so far. Was it a pretty straight forward install? or was it one of those parts where some modification is needed to use them?

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Re: The Steering and Suspension Thread

Post by adamky »

Awesome info so far. I didn't even realize that anyone made drop knuckles for our cars and I have never heard of "ackerman angle" before now. See, I told you I had nothing useful to add here!
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Re: The Steering and Suspension Thread

Post by Bubba »

@Cleantune, I've actually just recently added all of the GK Tech goodies to the car. I was running on stock knuckles with hand made adjustables and SPL RUCA's for years.

The install of the drop knuckles was pretty easy because I was swapping out Rear LCA's and knuckles at the same time, no busting of ball joints and stuff to fight with. Everything is rather tight on the install though due to the shortening of some of the knuckles mounting points. I won't count it as a modification needed to the product but you'll need to source slightly shorter nuts and bolts to replace the OEM stuff and make things easier for yourself in the future. Luckily I decided to throw all new stuff at the car when I did so I won't need to remove anything anytime soon.
Be sure to use the hardware that comes with the knuckles when attaching the brake calipers. I'll be using the Z32 e-brake assemblies along with Z32 rear calipers instead of dual calipers to start out my trial and error run. If I can avoid using a hydro e-brake then I will.

Right now I'm finishing up a tub project in my free time and getting my dumb ass Chase Bays harness problems sorted out. Don't make that mistake, find a different company to buy a harness from if at all possible. I've had nothing but issues since the day I got it. Luckily a friend of mine has already made a name for himself by fixing over a dozen of their harnesses here in the southeast.

If you guys are super interested in suspension dynamics then check out NissanRoadRacing.com
The forums over there are full of so much suspension knowledge it is ridiculous. I thought I had a good understanding until I started reading on that page. Haha

The threads about roll-center correction and traction issues are very good to read up on. There are even threads about budget-baller suspension mods where you turn Godspeed garbage into quality products.

I'll stop right there for now.
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Re: The Steering and Suspension Thread

Post by cleantune »

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@Bubba, thanks for the info. I agree there is a lot of great information on there about suspension settings.

I suppose it would be obvious to say, but worth mentioning that not all suspension settings are ideal for every driving type or chassis; even if it is the same chassis because based on the combination of parts the weight balance may be different and the driver may prefer some different settings.

Found this video last night that explained caster and camber gain fairly well (for those who are interested). This is for a drift-specific car, but the same principles can be applied for a grip setup:

https://www.youtube.com/watch?v=vp6vxb2QDVI

Some key points:

•for more "self-steer":
- increase caster (lower front hub pivot further in front of top strut mount, or top pivot)
- larger spacers and/or lower offset wheels (*when in combination with some caster)

•for flatter tire contact patch at more angle:
- increase negative front camber
*note: increasing front negative camber will decrease contact patch with the wheels straight, which will decrease front braking performance

•Flatter tire contact patch under lateral loads
-increase negative camber in rear
*note: front negative camber affects are also beneficial here because lateral g-force loads occur when steering

**the more caster, the more positive camber gain; with steering, more positive caster will be gained per degree of steering angle

•positive camber in the rear
-with softer rear suspension, the car will "squat" more (rear suspension compression), flattens tire contact patch
*note: "squat" with softer rear suspension also helps improve grip to some extent, increasing forward "tire bite"/ grip

Again if any one has anything to add or if any of this info is incorrect, please lemme know :]
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Re: The Steering and Suspension Thread

Post by cleantune »

.
I was watching a FD recap of Long Beach this year and noticed some interesting suspension on V. Gitten's Mustang:

Image
source: http://www.wreckedmagazine.com/blog/cat ... jr/page/3/

For those who don't already know, there is some serious thought that goes into pro drift car suspension setups. The 3-wheel action is interesting because it allows for faster drifts...I think. Here's why:

The rear suspension has A LOT of "squat". When coupled with a bit of positive camber the "squat" takes away some of the tire spin that would normally happen with stiffer rear suspension and translates into more forward "tire bite"/traction. This also happens to cause the (seemingly) stiffer front end to lift one tire when the car is under lateral loads.

In comes that "ackerman" term. So as described earlier, ackerman allows the inner wheel of a turn to steer sharper than the outer. This works when gripping, but while drifting the different angles of the wheels in a turn cause one wheel to "drag", slowing the drift a bit. Some drift setups run zero, or close to zero ackerman to limit this "wheel drag", but maybe this could be done by just lifting a wheel, which also may seem to happen during fast speeds (when "wheel drag" would slow the drift the most.

If the one wheel lifts during fast drifts, it wouldnt matter if the "normal" ackerman (even OEM spec) was used (to some extent) and the "planted" wheel would basically have zero drag; and be used to just point the chassis in the correct direction through a turn.

Downside is that the grip surfaces available for braking and steering are reduced.

...just brainstorming, haha. I heard an announcer point out the "three-wheel drifting" and he said something along the lines of "you wanna know why? ask Von and his team".
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Re: The Steering and Suspension Thread

Post by JustAlex »

cleantune wrote:.
I was watching a FD recap of Long Beach this year and noticed some interesting suspension on V. Gitten's Mustang:

Image
source: http://www.wreckedmagazine.com/blog/cat ... jr/page/3/

For those who don't already know, there is some serious thought that goes into pro drift car suspension setups. The 3-wheel action is interesting because it allows for faster drifts...I think. Here's why:

The rear suspension has A LOT of "squat". When coupled with a bit of positive camber the "squat" takes away some of the tire spin that would normally happen with stiffer rear suspension and translates into more forward "tire bite"/traction. This also happens to cause the (seemingly) stiffer front end to lift one tire when the car is under lateral loads.

In comes that "ackerman" term. So as described earlier, ackerman allows the inner wheel of a turn to steer sharper than the outer. This works when gripping, but while drifting the different angles of the wheels in a turn cause one wheel to "drag", slowing the drift a bit. Some drift setups run zero, or close to zero ackerman to limit this "wheel drag", but maybe this could be done by just lifting a wheel, which also may seem to happen during fast speeds (when "wheel drag" would slow the drift the most.

If the one wheel lifts during fast drifts, it wouldnt matter if the "normal" ackerman (even OEM spec) was used (to some extent) and the "planted" wheel would basically have zero drag; and be used to just point the chassis in the correct direction through a turn.

Downside is that the grip surfaces available for braking and steering are reduced.

...just brainstorming, haha. I heard an announcer point out the "three-wheel drifting" and he said something along the lines of "you wanna know why? ask Von and his team".
Very interesting thoughts on the speed/ackerman. I wonder if they really did setup the chassis to 3 wheel on purpose or if it was a accidental thing.
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