Results 1 to 13 of 13

Thread: Suspension for dummies

  1. #1
    Toymods Club Member #194 Conversion King Lambolica's Avatar
    Join Date
    Jul 2005
    Location
    NSW
    Posts
    2,109

    Default Suspension for dummies

    This is somthing I came across on another site and found it interesting for those contemplating playing with suspension setups.

    Quite obviously there are a number of things that effect suspension but I look at this as somewhat of a trouble shooting guide as to what planned changes may create, or why problems you have and how/why they can be solved.

    Front spring rate increase:
    More under steer; increase in proportional weight transfer to the front when rear wheel rate is not increased; reduces front traction when rear rate is not changed.
    Usable adjustment: 150-600 lbs/in
    Symptoms of too much adjustment: terminal under steer; front of car hops in corners; excessive wheel spin on inside front tire on FF cars.

    Front spring rate decrease:
    Less under steer; decreases proportional weight transfer to the front when rear wheel rate is not increased; increases front traction when rear rate is not changed.
    Usable adjustment: 150-600 lbs/in
    Symptoms of to much adjustment: Too much over steer; over steer then under steer if spring is so soft that the car bottoms out on lean, car bottoms out excessively with a jolting ride.

    Rear spring rate increase:
    More over steer; increase in proportional weight transfer to the rear when front wheel rate is not increased; increases rear traction when front rate is not changed.
    Usable range: 100-600 lbs/in
    Symptoms of too much adjustment: too much over steer; sidestep hop in corners; twitchy; pretty scary.

    Rear spring rate decrease:
    Less over steer: decreases proportional weight transfer to the rear when front wheel rate is not changed; increases rear traction when front rate is not changed
    Usable range: 100-600 lbs/in
    Symptoms of too much adjustment: car under steers; if way to soft car under steers then over steers as car bottoms out on lean; car bottoms out excessively with a jolting ride.

    Front anti-roll bar stiffer:
    more under steer
    Usable range: none to 1.25 inches in diameter
    Symptoms of to much adjustment: terminal under steer; lifts inside front tire off the ground witch can cause massive wheel spin on FF cars; also not good for most effective tire usage as inside tire is now doing nothing.

    Front anti-roll bar softer:
    less under steer
    Usable range: none to 1.25 inches in diameter
    Symptoms of to much adjustment: overstate scary; more like fun

    Rear anti-roll bar stiffer:
    more over steer
    Usable range: none to 1 inch in diameter
    Symptoms of too much adjustment: Big-time over steer. Can cause inside rear tire to lift off the ground.

    Rear anti-roll bar softer:
    less over steer
    Usable range: none to 1 inch in diameter
    Symptoms of to much adjustment: under steer; slow and boring

    Front tire pressure higher:
    less under steer by reducing slip angels on most tires
    Usable adjustment: up to 55psi hot
    Symptoms of too much adjustment: no traction- tire crowned so more under steer; adds wheel spin in FF cars; jarring ride; center of tire wears out

    Front tire pressure lower:
    more under steer by increasing slip angles on most tires
    Usable adjustment: not less then 20psi
    Symptoms of too much adjustment: edges of tire wear quickly because tire is folding over; feels mushy; tires chunk because low pressure means heat build up.

    Rear tire pressure higher:
    less over steer by reducing slip angles on most tires
    Usable range: up to 45psi hot
    Symptoms of too much adjustment: no traction—tire is crowned so more over steer; bad wheel spin on FR cars; jarring ride; center of tire wears out.

    Rear tire pressure lower:
    more over steer by incresing slip angles on most tires.
    Usable range: not less then 20psi
    Symptoms of too much adjustment: edges of tire wear quickly because tire is folding over; feels mushy; tires chunk because low pressure means heat build up

    More negative camber front:
    less under steer because of better lateral traction as tread is flatter on the ground under side load.
    Usable range: up to 3.5 degrees negative
    Symptoms of too much adjustment: poor braking; car is road crown sensitive; twitchy; front tires wear on inside edge

    More negative camber rear:
    less over steer because of better lateral traction as tread is flatter on the ground under side load. More rear grip
    Usable range: up to 2.5 degrees negative
    Symptoms of too much adjustment: more over steer; car feels twitchy in back; tires wear out on inside edge; less breakaway warning when limit is exceeded.

    Ride height to low (typical beginner mistake):
    car is twitchy with unpredictable dynamics. Bump steer make you life miserable.
    Usable range: usually 1.5-2.0 inches lower then stock unless car has been modified to go lower.

    Symptoms of too much adjustment:
    everything that could possibly go wrong: sudden over/under steer; twitchy due to bump steer; very harsh ride; premature tire wear.

    Toe in – front:
    car is stable going straight. Turn in is average
    Usable range: 0-1/8th inch
    Symptoms of too much adjustment: car has slow twitchiness under braking; feels odd; kills outside edge of tires

    Toe out – front:
    Car turns in well; works pretty well on FF car as they tend to toe-in under load.
    Usable range: 0-1/4 inch
    Symptoms of too much adjustment: Car is really twitchy under braking; car wanders on straight road; kills inside edge of tire

    Toe in – rear:
    car is less likely to over steer when the throttle is lifted
    Usable range: 0-1/8th inch
    Symptoms of too much adjustment: weird, slow, rocking movement in back; feels slow but still unstable; wears outside edge of tires.

    Toe out – rear:
    Helps car rotate useful in low speed and slalom courses; very common on FF pro rally cars.
    Usable range: 0-1/8th inch
    Symptoms of too much adjustment: not to good for street driving; causes lift throttle over steer; makes violent side to side rocking motions in the rear; tie wears on inside more.

    Positive front caster:
    helps stability; suspension will get more negative camber when turning; reducing positive caster reduces steering effort. (Negative caster is not usable)
    Usable range: 4-9 degrees positive
    Symptoms of too much adjustment: can increase under steer especially in cars with wide low-profile tires. Can increase steering effort.

    Single adjustable shock stiffer:
    Better turn in; better transient response; causes slower onset of over/under steer by slowing weight transfer depending on what end of the car is adjusted.
    Symptoms of too much adjustment: suspension becomes unresponsive; ride gets harsh; car skips over bumps, loosing traction; Causes a big delay in weight transfer resulting in strange handling like under steer then late corner stage over steer.

    Single adjustable shock softer:
    slower transient response; quicker onset of over/under steer
    Symptoms of too much adjustment: car oscillates due to under dampened spring motion, like a boat. Car gets twitchy in turns. Feels unstable.

    Taken from www.AE86drivingclub.com.au
    Beige.... The new Black!!!

  2. #2
    Forum Member Grease Monkey bbaacchhyy's Avatar
    Join Date
    Sep 2005
    Location
    South Australia
    Posts
    73

    Default Re: Suspension for dummies

    Great stuff there.

    This will be great toi point out to all those wanna be dorifto dudettes that think 1000 lb/in front springs on a road going AE86 is streetable !!!!!

    Cheers

    Michael B
    '84 MA61 with 7M-GTE
    Now 5sp, 5 stud,17x8" Ray's, big assed brakes and decent IC
    Better turbo in the wings as well as MAFT !!!!

  3. #3
    Junior Member Too Much Toyota RONA's Avatar
    Join Date
    Sep 2005
    Location
    NSW
    Posts
    7,493

    Default Re: Suspension for dummies

    Quote Originally Posted by bbaacchhyy
    Great stuff there.

    This will be great toi point out to all those wanna be dorifto dudettes that think 1000 lb/in front springs on a road going AE86 is streetable !!!!!

    Cheers

    Michael B
    Ironically its taken from an AE86 site lol

  4. #4
    Toymods Club Member #194 Conversion King Lambolica's Avatar
    Join Date
    Jul 2005
    Location
    NSW
    Posts
    2,109

    Default Re: Suspension for dummies

    *disclaimer*

    I use their site in for procurement of parts for the Anti-drift Corolla

    *end disclaimer*

    Most of the other articles seem to refer here...
    Beige.... The new Black!!!

  5. #5
    Forum Member Grease Monkey bbaacchhyy's Avatar
    Join Date
    Sep 2005
    Location
    South Australia
    Posts
    73

    Default Re: Suspension for dummies

    Quote Originally Posted by Corona RT142
    Ironically its taken from an AE86 site lol
    That was the best bit !!!!!
    '84 MA61 with 7M-GTE
    Now 5sp, 5 stud,17x8" Ray's, big assed brakes and decent IC
    Better turbo in the wings as well as MAFT !!!!

  6. #6
    Junior Member Backyard Mechanic buck naked's Avatar
    Join Date
    Oct 2005
    Location
    WA
    Posts
    334

    Default Re: Suspension for dummies

    I've got a question:

    How do you pick springs to match the stiffness of your shocks, to prevent over/under-dampening?

  7. #7
    AGE-16V Automotive Encyclopaedia Dimmy's Avatar
    Join Date
    Oct 2005
    Location
    NSW
    Posts
    862

    Default Re: Suspension for dummies

    Great info, cheers
    I have been pruned by old man river!!!!!

  8. #8
    Forum Member Grease Monkey bbaacchhyy's Avatar
    Join Date
    Sep 2005
    Location
    South Australia
    Posts
    73

    Default Re: Suspension for dummies

    Quote Originally Posted by buck naked
    I've got a question:

    How do you pick springs to match the stiffness of your shocks, to prevent over/under-dampening?
    There is actually a formula that you can work out the spring rate to match the car based on CoG, total weight, unsprung weight, and corner loading etc.

    Shocks are then dioalled in to suit.

    Not very simple really.
    '84 MA61 with 7M-GTE
    Now 5sp, 5 stud,17x8" Ray's, big assed brakes and decent IC
    Better turbo in the wings as well as MAFT !!!!

  9. #9
    Toymods Pimp Chief Engine Builder Norbie's Avatar
    Join Date
    Aug 2005
    Location
    QLD
    Posts
    3,806

    Default Re: Suspension for dummies

    Suspension tuning is as much art as science. The best way to pick an effective combo for your car/needs is to speak to other owners of your model who have modified their suspension, ideally someone who does circuit racing.

  10. #10
    User Conversion King
    Join Date
    Oct 2005
    Location
    NWA
    Posts
    2,885

    Default Re: Suspension for dummies

    very useful info

    thanks
    hello

  11. #11
    Junior Member Domestic Engineer myne's Avatar
    Join Date
    Dec 2005
    Location
    sa
    Posts
    629

    Default Re: Suspension for dummies

    There are also different approaches to everything.
    There are many ways to make a car turn.

    I've personally been wondering if stiffening the front springs about 20% and softening the front bar, while softening the rear springs a fair bit and stiffening the rear bar might achieve better braking and turn in on a FWD than the traditional stiffening the rear might do.

    I guess my first priorities should be re-acquiring my expired license, getting new tyres to remove the defect and registering my car, but it doesnt hurt to ponder.

  12. #12
    Junior Member Too Much Toyota oldcorollas's Avatar
    Join Date
    Aug 2005
    Location
    sydney
    Posts
    12,494

    Default Re: Suspension for dummies

    nm .......
    linky
    edit: can't find the original author tho ...
    Last edited by oldcorollas; 09-09-2007 at 08:51 PM.
    "I'm a Teaspoon, not a mechanic"
    "There is hardly anything in the world that a man can not make a little worse and sell a little cheaper" - John Ruskin (1819 - 1900)

    AU$TRALIA... come and stay and PAY and PAY!!! The moral high horse of the world!

  13. #13
    is a semi-motivated Domestic Engineer 1JZ~lux's Avatar
    Join Date
    Oct 2006
    Location
    QLD
    Posts
    591

    Default Re: Suspension for dummies

    + rep to you Lambolica. I'll be using this when I'm ready to do the suspension in my Lux. I'll be starting with something similar to Lances setup.
    Petrol is for washing parts, alcohol's for drinking but NITRO IS FOR RACING!
    My pictures, Returning some time in the distant future.
    RN85 Hilux + 1JZ-GTE = 298.0HP @ 14PSI -- 60' 1.956 ET 13.775 MPH 99.49
    Project Korruption - Stage 1: The Resto. KE35 Corolla Hardtop daily driver

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •