My lift needs adjustment/reverse rake

[TEujunga]

The "preload" myth is a hard one to stamp out.

Assuming a constant rate spring (which includes all front springs sold for the T4R, as far as I know), there should be no difference in ride quality due to "preload" on the spring.

Once installed in the vehicle, the spring is compressed to the same height under the weight of the vehicle regardless of how much "preload" was required to install it in the coilover. "Preloading" the coilover simply changes the effective position of the spring perch. It does not change the spring rate. A constant rate spring requires the same additional force to compress it a given additional distance no matter where you start from.

Longer springs with the same rate would ride the same. Stiffer springs would ride harsher no matter how much (or how little) "preload" was on them.

I admit it seems counter-intuitive and it's hard to visualize accurately. It would be easier to show with illustrations, but I'm not talented in that area.

 

[Vinsil]

Another quick question for anyone so I don't have to start a new thread. Is there a way to reduce the preload on my coilovers but still maintain the ride height? I've been doing a little searching and looks like it's possible to switch out to a longer/stiffer spring to reduce the preload? It's been a confusing read with varying opinions.

Looking at other people's Coilovers, looks like people are achieving their desired height with a lot less preload. :shrug:

Yup. You nailed it, longer front springs will allow you to reduce preload. It won't sole your reverse rake issue, but yes, at is the ideal way to do it. The issue will be longer springs usually are stiffer so you may find the ride being a little more harsh. Call Fox, they have the details.

I also second talking with Mike @Dobinsons. Great guy and lots of products to choose from.

Love your new wheels!

 

[Vinsil]

The "preload" myth is a hard one to stamp out.

Assuming a constant rate spring (which includes all front springs sold for the T4R, as far as I know), there should be no difference in ride quality due to "preload" on the spring.

Once installed in the vehicle, the spring is compressed to the same height under the weight of the vehicle regardless of how much "preload" was required to install it in the coilover. "Preloading" the coilover simply changes the effective position of the spring perch. It does not change the spring rate. A constant rate spring requires the same additional force to compress it a given additional distance no matter where you start from.

Longer springs with the same rate would ride the same. Stiffer springs would ride harsher no matter how much (or how little) "preload" was on them.

I admit it seems counter-intuitive and it's hard to visualize accurately. It would be easier to show with illustrations, but I'm not talented in that area.

This is something I disagree on. When you preload a spring, you are correct that it doesn't change the rate, but you lose travel and thus, when pushing the vehicle it will be a more harsh ride as the spring only has so much travel in it. Your springs give you the travel, the shocks dampen the action. More preload=less spring travel, thus less ride quality.

It is one reason when higher end coilovers have tender springs, mains and the like to allow the tension to be changed but also give full range of travel without so much preload it reduces the springs effectiveness. My .02

 

[Inked]

The "preload" myth is a hard one to stamp out.

Assuming a constant rate spring (which includes all front springs sold for the T4R, as far as I know), there should be no difference in ride quality due to "preload" on the spring.

Once installed in the vehicle, the spring is compressed to the same height under the weight of the vehicle regardless of how much "preload" was required to install it in the coilover. "Preloading" the coilover simply changes the effective position of the spring perch. It does not change the spring rate. A constant rate spring requires the same additional force to compress it a given additional distance no matter where you start from.

Longer springs with the same rate would ride the same. Stiffer springs would ride harsher no matter how much (or how little) "preload" was on them.

I admit it seems counter-intuitive and it's hard to visualize accurately. It would be easier to show with illustrations, but I'm not talented in that area.

Yup. You nailed it, longer front springs will allow you to reduce preload. It won't sole your reverse rake issue, but yes, at is the ideal way to do it. The issue will be longer springs usually are stiffer so you may find the ride being a little more harsh. Call Fox, they have the details.

I also second talking with Mike @Dobinsons. Great guy and lots of products to choose from.

Love your new wheels!

Thanks for the insight guys. There's certainly been some debate as suggested. I'm way too much of a novice to understand or even articulate in this debate, but I appreciate the conversation.

If there's uncertainty to whether or not a longer spring helps improve the ride by lessening the preload, why go to the expense of changing out the spring? I would think this has been done by many here. There must be some real world experiences.

 

[TEujunga]

I stand by what I wrote above.

Anytime you lift the T4R's front ride height, no matter whether it's through a "preloaded" coilover, spacers, or longer/stiffer springs, you're limiting the amount of extension travel available from the IFS because it's now riding closer to the downward limit of its travel.

As long as your wheeling isn't so extreme as to cause you to hit the suspension's extension limit constantly, your ride quality will remain about the same (ride quality may become harsher the higher you lift the suspension, but that's because of geometry issues, not because of any "preload" on the spring).

 

[cmilviper]

Another quick question for anyone so I don't have to start a new thread. Is there a way to reduce the preload on my coilovers but still maintain the ride height? I've been doing a little searching and looks like it's possible to switch out to a longer/stiffer spring to reduce the preload? It's been a confusing read with varying opinions.

Looking at other people's Coilovers, looks like people are achieving their desired height with a lot less preload. :shrug:

Usually those who switch out springs on their coilovers like that, are doing so due to additional weight they have added.

Like if you were to add a bumper & winch yourself, the front end height would drop some. So to get it back to your original height, switching out the spring could make sense, rather than add a lot more preload to your existing setup.

Going to a heavier spring like that in the front without having the additional weight could negatively impact ride quality ect.

 

[TEujunga]

Amendment to previous answer:

A lift created by using a longer spring will provide for more suspension down travel than one created by "preloading" a shorter spring. However, these are limits likely to be encountered only in extreme wheeling, not in ordinary driving.

 

[Jetboy]

The higher the initial ride height- the more impact will transfer to the body regardless of spring or shock rate or design. It's a matter of geometry of the control arms. The best ride will be the the control arms level to the ground. How it sits from the factory.

That said - pre-load in a threaded coilover does nothing more than change the static ride height. The entire suspension travel range from droop limit to bump stop should be within the spring's elastic range. Assuming the spring is not a progressive rate coil, the preload should have no effect on spring rate at any location within the range of motion of the front suspension.

What can also negatively effect ride quality is the wrong static ride height. In addition to more jarring impact from bumps due to geometry, you also have less range downward. Any drop that exceeds the available down travel will cause a harsher ride.

If you do set the collar so far as to exceed the spring's range of elastic motion - then you have a lot of other problems. If you brick the spring - meaning it compresses so much that the coils all touch eachother typically you end up with this (which is the result of a top spacer not a bricked coil, but the outcome is the same):

That's usually bad for ride quality...

 

[TEujunga]

The higher the initial ride height- the more impact will transfer to the body regardless of spring or shock rate or design. It's a matter of geometry of the control arms. The best ride will be the the control arms level to the ground. How it sits from the factory.

That said - pre-load in a threaded coilover does nothing more than change the static ride height. The entire suspension travel range from droop limit to bump stop should be within the spring's elastic range. Assuming the spring is not a progressive rate coil, the preload should have no effect on spring rate at any location within the range of motion of the front suspension.

What can also negatively effect ride quality is the wrong static ride height. In addition to more jarring impact from bumps due to geometry, you also have less range downward. Any drop that exceeds the available down travel will cause a harsher ride.

If you do set the collar so far as to exceed the spring's range of elastic motion - then you have a lot of other problems. If you brick the spring - meaning it compresses so much that the coils all touch eachother typically you end up with this (which is the result of a top spacer not a bricked coil, but the outcome is the same):

That's usually bad for ride quality...

Thanks for helping me stamp out the dreaded "preload myth." That's what I was trying to say, but you explained it much better.

To recap, "preload" itself doesn't affect ride quality except when the preload is extreme, and then only at the extremes of suspension travel. If you're running that much preload, you have a lot more to worry about than ride quality.

 

[Inked]

Thank you all...this is all great info. I feel better now about the amount of preload on my CO's and won't be needing to address the springs unless adding some additional weight. I don't do any extreme wheeling or rock crawling, but do enjoy getting out into the country and dunes. I keep it pretty simple, so I'm in good shape. Thanks again!