[Aussie as a Drover]

G’day,
Long time lurker, first time posting. I’m after some input on a low full RUF.

I’ve measured 80mm difference between the mounts of the front and rear springs, so I’m planning on a 40mm chassis extension as well as moving the rear mount back 45mm, raising the mounts higher at the same time. Shouldn’t be a problem moving the front mount 25mm higher, but being a Drover(NT) with the spring is directly under the chassis, and the chassis angling down where the rear mount is, the best I could do with the rear is keep it at the same hight.

I’m estimating that’d end up being about 35mm higher than stock with the extra bow the rear springs have compared to the front. I’m aiming for stock hight, what could I do with shackles or any other tricks to drop it down further?

I don’t want to move the axle forward, no need to tyre clearance, it’ll be on bar grips very soon.

I was looking on Indian sites trying to source the OEM springs with tapered leaves. I didn’t have any luck, but found the Dr nano composite springs. There’s almost no mention of them on Auszookers. I got a quote for 2 rear sets shipped to aus for $1200. The dude reckons the standard hight comfort springs are “very comfortable compared to stock springs”. I’m tempted to find out.
Cheers! Charles

[MrRocky]

Shackle angle and spring length is the biggest factor when talking about leaf comfort.
For sierras there really isnt an off the shelf solution for what you seem to be wanting to achieve you will have to mix and match spring packs standard/lifted and number of leafs.
If you get your measurements off there is also the risk your shackle will "invert".
I ran a ruf using efs hd lwb top springs and 75mm bumpstop extensions with a mixed bag of individual leafs to sit at standard ride height whilst still running a 32" tyre

[alien]

Through-frame hanger?

[Gwagensteve]

I'll provide some input.

Just a correction though - "Full RUF" means leaving the spring hanger location in the stock position and moving the axle forward. Moving the spring hanger bolt hole backwards at all is whats known as "1/2 RUF"

There is no problem achieving stock ride height with a RUF. the whole point of a RUF is that the rear springs have a much lower rate than the front springs so the additional camber gets eaten up. The key is tuning the leaf packs to provide the height you want. The height you end up with is much more about the rate of the leaf rather than where you put the mounts.

Remember also you can redrill the spring saddle on the axle and the spring plate to move the axle relative to the spring centre bolt too.

if you move the rear hanger back you won't need 40mm of extension. I'll explain why.

A Sierra with stock front suspension is set up for just slightly more droop than compression. The stock shackle angle takes this into account. When you go low RUF, the spring is sitting very deep into it's travel (i.e it's very flat, so it's close to as long as it can possibly get) Therefore, the shackle doesn't need to have much travel forwards, only backwards, so the shackle sit very flat. This lowers the car and increases caster, both good things.

There is only one way to set up RUF - mock the front end up with a main leaf only and cycle the suspension. All the theory in the world can't make up for mocking it up.

I don't think you're trying to do anything unique, I've built RUF cars at stock height using an OME rear leaf, ~37mm of extension and about 1" over stock shackles. This car drove very well and was stock height. Compared to what you're trying to do, the only difference was the axle location, which as I've pointed out you can correct by re drilling spring plates and saddles, which is completely reversible and basically undetectable.

Stay away from composite springs. They're fragile, have a set rate, so there's no possibility of tuning them if the car sits too tall in the front, and they're expensive. They also can't provide extended travel - they will fight droop beyond their set camber with the same rate they fight compression. This isn't the case with steel leaves where the leaves will fan apart on droop so they can cheat extra droop.

[vet 180]

Gwagensteve wrote:

I'll provide some input.

Just a correction though - "Full RUF" means leaving the spring hanger location in the stock position and moving the axle forward. Moving the spring hanger bolt hole backwards at all is whats known as "1/2 RUF"

There is no problem achieving stock ride height with a RUF. the whole point of a RUF is that the rear springs have a much lower rate than the front springs so the additional camber gets eaten up. The key is tuning the leaf packs to provide the height you want. The height you end up with is much more about the rate of the leaf rather than where you put the mounts.

Remember also you can redrill the spring saddle on the axle and the spring plate to move the axle relative to the spring centre bolt too.

if you move the rear hanger back you won't need 40mm of extension. I'll explain why.

A Sierra with stock front suspension is set up for just slightly more droop than compression. The stock shackle angle takes this into account. When you go low RUF, the spring is sitting very deep into it's travel (i.e it's very flat, so it's close to as long as it can possibly get) Therefore, the shackle doesn't need to have much travel forwards, only backwards, so the shackle sit very flat. This lowers the car and increases caster, both good things.

There is only one way to set up RUF - mock the front end up with a main leaf only and cycle the suspension. All the theory in the world can't make up for mocking it up.

I don't think you're trying to do anything unique, I've built RUF cars at stock height using an OME rear leaf, ~37mm of extension and about 1" over stock shackles. This car drove very well and was stock height. Compared to what you're trying to do, the only difference was the axle location, which as I've pointed out you can correct by re drilling spring plates and saddles, which is completely reversible and basically undetectable.

Stay away from composite springs. They're fragile, have a set rate, so there's no possibility of tuning them if the car sits too tall in the front, and they're expensive. They also can't provide extended travel - they will fight droop beyond their set camber with the same rate they fight compression. This isn't the case with steel leaves where the leaves will fan apart on droop so they can cheat extra droop.

X2 on full ruf with re-drilled plates and saddles.

The other benifit to this is if you want to go bigger tires at a later date or even sell the car to someone that does its very simple to move the axle forward.

Sent from my SM-N960N using Tapatalk

[Aussie as a Drover]

Thanks for this, guys. I’ll pull the wheel off and read this a few more times, makes sense though.

[fordem]

Gwagensteve wrote:

There is no problem achieving stock ride height with a RUF. the whole point of a RUF is that the rear springs have a much lower rate than the front springs so the additional camber gets eaten up. The key is tuning the leaf packs to provide the height you want. The height you end up with is much more about the rate of the leaf rather than where you put the mounts.

Steve, I'm a little puzzled by this - we're discussing a live axled vehicle - isn't the camber fixed and determined by the axle? How would changing the springs or the axle's position (front to rear) change the camber?

[Gwagensteve]

Camber is the term for the arch of a leaf spring. It’s also used describe the arch of roads so they drain to the gutters.

[fordem]

ahhh - I knew that, but for some reason I kept focusing on camber angle - thanks for clarifying.