A few basic suspension tuning questions

[benno505]

Hey guys,



getting the charger sorted for a bit of autocross in june.
booked in for a dyno tune and just purchased a hydroboost system.

it has a 4 link with wilwood discs on the rear and viking double adjustable coils and on the front a custom chromoly k member with viking coils and wilwoods, everything is fully adjustable.

what would be a good starting point for:

camber:
caster:
toe:
compression clicks on the vikings:
rebound clicks on the vikings.

car is 90% street cruiser. approx weight of car is 1650kg

[bryant]

check out the ron sutton posts at the top of this section. you should be able to get an idea of the base settings for alignment from them.
one of the things i came away with is get as much caster as you can. some where between 6 degrees to 9 degrees will be a good window to start with.

[LemonTwisted]

Here's what I've seen recommended for the original suspension Mopars.



The Caster number is probably limited by the original UCA design but I would bump it up if you can.

[benno505]

Here's what I've seen recommended for the original suspension Mopars.



The Caster number is probably limited by the original UCA design but I would bump it up if you can.

only difference is, which i am not sure will make a difference but my suspension is far from stock mopar, but that diagram should give me a good starting point, thanks.

[benno505]

check out the ron sutton posts at the top of this section. you should be able to get an idea of the base settings for alignment from them.
one of the things i came away with is get as much caster as you can. some where between 6 degrees to 9 degrees will be a good window to start with.

thanks, i believe i am currently on 7 * caster, i turn the wheel slightly at speed and almost throws me out the window, is that normal for that high of caster? i would like a bit more striahgt line stability what would you recommend? i will also take a look at ron suttons post thanks

[bret]

Any competent suspension supplier should be able to supply alignment info for thir product. Any competent shock manufacturer should be able to give you a baseline for shock tuning. I would suggest starting with yoir respective suppliers for that info. If they cannot provide this info, pop back in here and we'll get into it more.

[dhutton]

thanks, i believe i am currently on 7 * caster, i turn the wheel slightly at speed and almost throws me out the window, is that normal for that high of caster? i would like a bit more striahgt line stability what would you recommend? i will also take a look at ron suttons post thanks

I installed the full Hotchkis setup with a Firm Feel steering box and steering arms on a friend's 68 Charger. I set it at -.5 camber and 6 caster, 1/16 toe. It is very well behaved, nothing like you describe above.

Don

[BMR Sales]

Any competent suspension supplier should be able to supply alignment info for thir product. Any competent shock manufacturer should be able to give you a baseline for shock tuning. I would suggest starting with yoir respective suppliers for that info. If they cannot provide this info, pop back in here and we'll get into it more.

Agreed!

[nokones]

Please note the note (** Some road racers and autocrossers like toe out) on the posted chart. Most road racers like toe in for the front. For auto crossing you should be looking at 1/8" - 1/4" and in some cases 5/16" toe out. I believe that would be a negative 1-3 in degrees. For the rear on IRS type suspensions try about 1/4" toe in (positive 3 degrees). For caster try about 5 - 5 1/2 degrees positive for starters.

It appears that your suspension has coilovers and I am assuming that you can adjust the ride height. If that is the case make sure that your cross weight is 50% for auto crossing. If you have the ability to weigh your car on 4 scale pads make sure that the scale pads are bubble/laser level with each other otherwise you're wasting your time unless your just weighing your car for gross weight. Also, before you weigh your car, put the driver's weight in the driver's seat, disconnect all the swaybars, air up the tires to race pressures, and put the amount of gas in the tank you plan to run with. Don't forget to jouce each corner after an adjustment. After you get the 50%, drive the car on and off the scale and recheck your corners again.

[benno505]

Please note the note (** Some road racers and autocrossers like toe out) on the posted chart. Most road racers like toe in for the front. For auto crossing you should be looking at 1/8" - 1/4" and in some cases 5/16" toe out. I believe that would be a negative 1-3 in degrees. For the rear on IRS type suspensions try about 1/4" toe in (positive 3 degrees). For caster try about 5 - 5 1/2 degrees positive for starters.

It appears that your suspension has coilovers and I am assuming that you can adjust the ride height. If that is the case make sure that your cross weight is 50% for auto crossing. If you have the ability to weigh your car on 4 scale pads make sure that the scale pads are bubble/laser level with each other otherwise you're wasting your time unless your just weighing your car for gross weight. Also, before you weigh your car, put the driver's weight in the driver's seat, disconnect all the swaybars, air up the tires to race pressures, and put the amount of gas in the tank you plan to run with. Don't forget to jouce each corner after an adjustment. After you get the 50%, drive the car on and off the scale and recheck your corners again.

Thanks, i am just setting up for street at the moment and then tune from there, i dont have access to weights or anything alike, i do have an aligning tool which i have been using seemt to work well, i forget the name, supertrax or something. coil overs are height adjustable and double adjustable. my UCA's are adjustable, My LCA's are adjustable, sway bar is adjustable, so may options with this setup.(magnumforce)

[pitts64]

I did the Ron Sutton method, KPI + 2 and it worked well for me..