Need help with coil overs
- Thread starter sunshine
- Start date
LT.
Well-Known Member
- Location
- Los Alamos, New Mexico
If you know some of the information then you should check out FOA's site for figuring out your spring rates. If not, then let us know what they are going on and angles and most of us can at least get you in the ball park. Also, there are a few companies that will exchange the coils provided that they are not damaged just in case you get the spring rates wrong.
LT.
LT.
Thanks, they are on my buggy, I have Fox air shocks that im am swapping out to coil overs. It has a 347 Stroker in it and the rear I am swapping out the 5 Gal fuel cell to 12 gal. And there is a warn 2500 Winch and radiator in back, not sure of the overall weight but could weigh it. Been looking for some scales to get a unsprung weight but haven't found one that will go up that high.
Thanks, I already have shocks, just need to get springs. If I have the total weight of the car, can you subtract the axles weight?
- Location
- Fruita, CO
Gonna need some more info to help you.
Front weight?
Rear weight?
Total weight?
Coilover mounts location(on axle, on links) and rough angle of shocks at ride height?
stroke of coilover?
use of rig?(go-fast will generally require more spring than a dedicated crawler.)
Front weight?
Rear weight?
Total weight?
Coilover mounts location(on axle, on links) and rough angle of shocks at ride height?
stroke of coilover?
use of rig?(go-fast will generally require more spring than a dedicated crawler.)
LT.
Well-Known Member
- Location
- Los Alamos, New Mexico
I had to re-learn some on shock tuning. For crawling you will usually have about 4 to 6 inches of shaft exposed. This will depend on how long of travel you have on your shocks. Usually a 40% of compression and 60% extention. On a rig that will see high speeds you will want closer to a 50% ratio sometimes even more.
When I did my home work on this I got a set of racer scales and weighed all four corners. Then I had to subtract the weight of the wheels, tires, axles, half the weight of the links, and same for the shocks.
LT.
When I did my home work on this I got a set of racer scales and weighed all four corners. Then I had to subtract the weight of the wheels, tires, axles, half the weight of the links, and same for the shocks.
LT.
LT brings up some good points. With one ton axles you will have 700-800 pounds per axle that is "unsprung weight" and that needs to be taken off of the total axle weight to get "sprung weight". The angle of the shock, and position of shock mount also need to be taken into account.
http://www.f-o-a.com/calculator.html
If you look at this calculator it asks for all of this info, and it helps get you close, but you still will need to do some testing. Two rigs with the same travel, weight, shocks will behave differently based on things like link geometry and what not.
On a dual purpose rig I would go 50/50 bump/droop and a minumum. Spring rates seem to work out better if you go with more bump, like 60/40 bump/droop.
http://www.f-o-a.com/calculator.html
If you look at this calculator it asks for all of this info, and it helps get you close, but you still will need to do some testing. Two rigs with the same travel, weight, shocks will behave differently based on things like link geometry and what not.
On a dual purpose rig I would go 50/50 bump/droop and a minumum. Spring rates seem to work out better if you go with more bump, like 60/40 bump/droop.
RockMonkey
Suddenly Enthusiastic
Use the method Mesha mentions above. Get 4 coils of any known rate. Put them on and measure how mich they squish. Just measuring unsprung weight won't work unless your coil overs are mounted perfectly vertically.
Basically it's nearly impossible to calculate perfectly and get it right the first time. Just take a guess and buy some coils, then swap them based on the results. Usually people with dual rate coils end up buying one more spring per corner. Start with the cheapest coils you can find that are the right diameter and length. 150/300, 125/250 are probably decent starting points for most. Coil tuning is an art, not a science, that's why you can't do it with a calculator.
Basically it's nearly impossible to calculate perfectly and get it right the first time. Just take a guess and buy some coils, then swap them based on the results. Usually people with dual rate coils end up buying one more spring per corner. Start with the cheapest coils you can find that are the right diameter and length. 150/300, 125/250 are probably decent starting points for most. Coil tuning is an art, not a science, that's why you can't do it with a calculator.
TEAM FRED
Registered User
- Location
- Centerville
I've got a couple springs you can use to get you close.