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thanks for all the help and advice on here guys.
yesterday i put the 2" lifted Rears up front, 35mm further back on the hangers, with commodore wagon rear shocks, and the little beast has never ridden so well.
I put a 1" bumpstop extension into it, and it is going great guns.
I didn't have time to make the 2" extended shackles and put them on the back with the longer shocks, so the ute still looks like it's driving uphill, but they are still to come soon, and then I will have to wait for something to break, i won't have anything left to do on it for a while. Imagine that! Nothing to do on a sierra!
Except save for the 1.6 engine.......
Puk
Last edited by Puk on Wed Oct 24, 2007 6:09 pm, edited 1 time in total.
The front shackles are actually the standard ones. they sit at about 45 degrees forward on flat ground with the 2" lifted springs moved about 35mm further back in the hangers. I know you lose the effect of the longer wheel base, but it was easier all round, and i didn't want too much extra height in the front, as the back is playing catch-up already.
Puk wrote:The front shackles are actually the standard ones. they sit at about 45 degrees forward on flat ground with the 2" lifted springs moved about 35mm further back in the hangers. I know you lose the effect of the longer wheel base, but it was easier all round, and i didn't want too much extra height in the front, as the back is playing catch-up already.
Puk
Beautiful, thats what I wanted to hear, the more standard it looks, the better . Did you just re-drill the rear hanger? I figured I can gain 35mm by cutting the hanger off, and welding it back on backwards.
Can 'fix' the wheel base lack by re-drilling the perch on the axle about an inch back if required.
Wheeling on completely wicked angles, without even looking stable.
It all fit quite nicely, and is a LOT better behaved on the bumpy stuff now.
As i was undoing one of the lock-nuts on the top of the existing shock absorber, the shaft sheared off. I am SO glad i replaced them.
It all looks pretty stock anyway, as i have a big ugly bull-bar that covers it all pretty well, and i reckon it will be hard to see the shackles when i put them on the back because of the associated ute-type stuff covering it pretty well.
I will post some pics once i get the shackles on the back.
I got the 2"longer rear shocks from suzisport in bris for $110 plus postage, which i thought was pretty good value. the heavy duty ones are $140
Even with the hanger back 35mm I wouldn't never have thought they'd fit.
I'm running a silmilar setup and there's absolutely no way they'd fit with anything less than than 110mm shackles. I made various sets and tried. I'm probably not back 35mm on the hanger though. Anything more than about 20-25 I think and the chassis was going to be a factor above the spring eye. I'm still a little more horizontal than 45 degrees in the shackle too. But that was mine, good on you if they fit with a 45 degree angle. Nice work.
I did my RUF on the weekend, though i went for a different option. I picked up a rear main leaf from the back of an LJ81 ute, strapped that on the 2" rear leaves i had, there fore ending up with a set of leaves 30mm shorter than the 2" lifted set. Effectively moving my front axle forward an inch without having to redrill the hangers.
Puk wrote:
Excuse my ignorance, but what are the problems i am likely to encounter if they go much over the 45 degrees?
Puk
The closer to horizontal the shackle is, the effective stiffness of the leaf is higher. A leaf spring is at its physical softest when the shackle is vertical. Also when the shackle reaches perfectly horizontal the spring can no longer travel further in that direction, acting like a rather bad bump stop. If the spring manages to go beyond horizontal, you got serious problems.
Tanshi, hows the setup been going this week, notice the difference?
Wheeling on completely wicked angles, without even looking stable.
Front is really good, nice and soft but ride the bumps well. the rear i still need to get some softer bushes for as they are binding a little. all in all im really happy.
Highway-Star wrote: A leaf spring is at its physical softest when the shackle is vertical.
I have to disagree, if the shackle is vertical the force goes directly up the shackle into the chassis rather then the shackle pivoting backward. The angle between the shackle and the spring must be smaller then 90 degrees, therefore the force of the bump will cause the shackle to rotate at the chassis pivot.
I had my ruf done at overkill with stock rear spring mount. The shackles sit on a 45 but Ive noticed in my pile of spare springs some are maybe 1/2 " longer so the shackle goes forward and the spring rests on the top shackle mount. All these springs have the same lift just variances in lenght.
I ran 2" springs in the rear so it sits level as well.
Nik
Highway-Star wrote: A leaf spring is at its physical softest when the shackle is vertical.
I have to disagree, if the shackle is vertical the force goes directly up the shackle into the chassis rather then the shackle pivoting backward. The angle between the shackle and the spring must be smaller then 90 degrees, therefore the force of the bump will cause the shackle to rotate at the chassis pivot.
Greg
OK. I'm basing my statement from some statements made in the following book:
Milliken, W.F. and Milliken, D.L. (1995) Race Car Vehicle Dynamics. SAE.
But I do see where you are coming from, there would be more shock loading of the chassis. However I belive the theory works on the fact that when the shackle is horizontal all the bending of the spring is transfered completely in lateral motion of the shackle (for an instant anyway). However when the shackle is at say 45 deg, the bending of the spring the same amount requires more angular velocity from the shackle, because it must moves the shackle through a greater arc to generate the same quantity of lateral displacement. This is a reason why extended shackles are often desirable, because the same amount of lateral displacment can be achieved for a lesser angular displacement.
Something like that anyway.
Sorry to deviate this a bit.
Wheeling on completely wicked angles, without even looking stable.
I agree that horizontal is the worst case and 45 probably isn't ideal but vertical is bad as well. My setup the front are at about 45 and ride very well but the rears are vertical and it's terrible because the force gets transfered straight into the chassis.
It depends on the spring, it the spring is flat ie no arc which may be the case from your Race Car reference when the spring flexs the shackle actually travels inward as the spring arc's up rather then in our normal situation where the spring have arc and tend to flatten.
any pics of yours justcruizin to see how the ruf sit?? it moves the diff forward ever so slightly yes?
whats it like when bent up? ive got extended shackles on mine but they arent at the best angle and want it to flex up a bit better, rear even tho shackles are vertical'ish it bends up fine, i might just drop a leaf from the rear to get a little more!!!
It flexs great, my issue is reasonably quick bumps go straight up the shackles into the chassis rather then pivoting it. Two different things slow flex v's quick bumps
there is a problem with doing this on NT sierras and thats with the rear spring mount.
It doesnt give enough room to comfortably re drill the rear mount,
NT rear hangers are more U shaped rather than sloping with the WT, which is a PITA
85 LWB w. FRP Canopy
Ca18det conversion in progress, Vit PS, RUF,
6.5:1's, 33x12.5 Bfg's, custom front and rear bars.
looks good justcruizin, did you just redrill the hangers, adjust bumpstops and fit the shackles up as well as making sure the lines and shocks were fine??
what 2inch lifted springs did you use in the front???
mick85 wrote:looks good justcruizin, did you just redrill the hangers, adjust bumpstops and fit the shackles up as well as making sure the lines and shocks were fine??
what 2inch lifted springs did you use in the front???
Just redrilled the rear hangers, bumpstop haven't been modified, 2" longer shackles and about 2" longer brakelines. Shocks are commodore wagon rears. I don't know what brand springs they are I bought them second hand
11_EVL : Looking good mate.
Is that front mount some sort of drop shackle or is it fixed?
Are they standard rear springs??
How much lift did it give the front? Cheers Jas.
yes it is a drop setup
not sure about ride height as yet because im changing motor steering front bar. but i think they were near new 2" rears. it was a relatively easy setup to do
11_evl wrote:yes it is a drop setup
not sure about ride height as yet because im changing motor steering front bar. but i think they were near new 2" rears. it was a relatively easy setup to do
exactly what ive drawn up to run on the front of mine. Should have them welded up tomorro morning and all fitted up this weekend...
Approach doesnt look too bad.
What did you have to do regarding shock mounts/bumpstock locations etc???
i havnt sorted than out yet but being RUF i will have to move them forward about 30mm i think and because im trying to (setup) for 33s and run 31s, i will need to extend about 1-2" im guessing. either that or ill just cut heaps out of the inner guards. shocks im useing ranchos adjustable but ill set the hoops up LAST. i need to get motor and box in b4 i get tooo excited
thanks for the reply just cruizin, no other mods to front tailshaft etc? how far back did you redrill the hangers??? exactly in line with the original holes?
But not much.
