Suspension lifts - some comments

[Gwagensteve]

I seem to answer this about twice a week, so here goes with some information about suspension kits and why they are the way they are.

Stock sierras, depending on how heavy they are and how much they have sagged, have around 25-40mm of front compression travel and 55-75mm of rear compression travel.

90% of suspension manufacturers don't care what size tyre you want to fit on your car. Really, they just don't. What they are interested in is load carrying capability and ride quality. Everyone hates the ride quality in sierras, and that's what they are trying to fix.

Do 2" springs allow me to run more tyre?

No. Just No. Never. Why not? Well, when you flex the car up off road, the tyres will still move up into the guards just as far as they could before, so they will hit just as badly as they did before you put the springs in.

Why do the springs have lift in them then?

Because manufacturers are trying to improve ride at speed, and to do it, they are increasing the compression travel. This allows the axle to travel up more before it hits the bumpstop. This should mean that the car can hit a bigger bump before it starts to make the car jolt. It also allows more movement for the shock absorber to work to slow the axle and smooth the ride by stopping the axle smacking into the bumpstop.

I have put lifted springs in how much travel have I gained?

Probably none. you may have lost some. Wheel travel on a leaf sprung car is limited by shock absorber length and spring length. neither of these things can be radically changed (more than 30mm or so) without doing significant fabrication work.

I'll just put longer shocks in then...

Easy tiger! If a stock sierra shock is 9" long fully compressed and 15" long fully extended, and you want a shock that is, say, 20" long fully extended, then the shock will have to be maybe, 12" long fully compressed and 20" long fully extended. You can't have a shock that is longer extended without making it longer compressed.

That compressed length has to go somewhere, so unless you increase the minimum distance between the upper and lower shock mounts, you will break something when you compress the car.

So, to fit a longer shock, you have to space down the bumpstop and/or raise the upper shock mount.

Why does Gwagensteve hate 3" springs on sierras?

There are a couple of companies making 3" "lift" springs for sierras. they ride like crap and don't offer more travel. Why? Because to hold the height in a spring very short (like the front of a sierra) A) the spring needs to have a higher rate than stock and B) you can't fit a longer shock without fabrication work and C) the range of shackle movement is limited so, the effect is really that the amount of total travel doesn't increase, the spring rate goes up, and because of the higher rate, there is very little chance you will ever reach the bumpstop, so the car ends up choppy and stiff.

This will probably raise more questions than it answers, but these issues seem to come up so often I thought it might be worth putting it down here.


Steve.

[suzuki boy]

Bit of spare time hey?

Deffinatly into the bible!

[MART]

x 2 , Cheers Paul.

[lay80n]

Bible Bound. Top stuff Steve, now if you have any ideas of how to make people read the bible, or search, before asking the same NOOB questions, im all ears .

Good stuff mate

Layto....

[St Jimmy]

good stuff wish i knew this before i put sorry canott remember name of springs springs and enforcer big bore shocks on my zook i took shops advice and the springs are so stiff that it shakes your teeth out can i soften them up ? as they have a heavy duty leaf at the bottom sorry about the spelling

[Gwagensteve]

Bible Bound. Top stuff Steve, now if you have any ideas of how to make people read the bible, or search, before asking the same NOOB questions, im all ears .

Good stuff mate

Layto....

Dunno mate, maybe PM Grimbo

[St Jimmy]

Bible Bound. Top stuff Steve, now if you have any ideas of how to make people read the bible, or search, before asking the same NOOB questions, im all ears .

Good stuff mate

Layto....

how about READ THIS FIRST in captial letters

[Gwagensteve]

can i soften them up ? as they have a heavy duty leaf at the bottom

Yep, you can pull leaves out until it works the way you want.

Make sure you measure your height before and after, and try and keep your longer leaves. The longer leaves help prevent you bending the main leaf which is common in sierras used offroad. Pull the overload leave(s) first.

Try to run maybe a minimum of 3 leaves in the front and four in the rear. The trade off will be excessive axle wrap and the car will be too low. It depends on how heavy your car is and how low you want it.

The advantage of starting with long (tall) stiff springs is that when you pull leaves and the springs level out they are nice and long and you will get lots of droop if your shocks are set up properly.

Steve.

[lay80n]

Bible Bound. Top stuff Steve, now if you have any ideas of how to make people read the bible, or search, before asking the same NOOB questions, im all ears .

Good stuff mate

Layto....

how about READ THIS FIRST in captial letters

Tried that, even had Antt go on with pirate style flaming on people that are to lazy to search or look at the bibles first, but still no luck.

Layto....

[St Jimmy]

Bible Bound. Top stuff Steve, now if you have any ideas of how to make people read the bible, or search, before asking the same NOOB questions, im all ears .

Good stuff mate

Layto....

how about READ THIS FIRST in captial letters

Tried that, even had Antt go on with pirate style flaming on people that are to lazy to search or look at the bibles first, but still no luck.

Layto....

i know I GOT FLAMED a few times

[just cruizin']

So it get's back to: if you want to run bigger tyres, virtual lift or body lift.


On a side note, why don't spring manufactures offer slightly longer "lifted" springs to assist with the shackle angle. I know running standard shackles you probably couldn't increase by too much but anything would help.

[Gwagensteve]

Interesting point, but there are some liability issues.

A longer spring would have to work with a bumpstop spacer or the shackle angles would get excessive. I would also guess that ideally, a longer shackle would have to be part of the package, which would cause some more legality issues.

I guess the way around it is like beadlocks- sell them as offroad use only.

I think that Mugginsmoo is running longer rear leaves in Doof, but in Greg's cousin's therapists car we just moved the rear shackle hanger forward 2" on the rear, and gained back the 2" of travel we lost with bumpstop spacers.

Steve.

[lay80n]

So it get's back to: if you want to run bigger tyres, virtual lift or body lift.

Or SPOA. [opens can of worms, runs away ]

Layto....

[Gwagensteve]

There's no argument from me (#1 SPOA hater) that SPOA fits a bigger tyre. I agree with any SPOA lover in relation to that.

My well known opposition to SPOA only relates to how easy they are to do and all the other alleged benefits.

All of the same "rules" in relation to the operation of leaves and avialable wheel travel still apply to SPOA and SPUA.

Steve.

[lay80n]

There's no argument from me (#1 SPOA hater) that SPOA fits a bigger tyre. I agree with any SPOA lover in relation to that.

My well known opposition to SPOA only relates to how easy they are to do and all the other alleged benefits.

All of the same "rules" in relation to the operation of leaves and avialable wheel travel still apply to SPOA and SPUA.

Steve.

Just stirring the pot I agree Steve. if done properly, SPOA is not a bad mod, but if done quickly or "cheaply" then its a death trap.


Layto....

[muppet_man67]

So does that mean that I can't fit 31's with a 2 inch suspension lift?

[grimbo]

So does that mean that I can't fit 31's with a 2 inch suspension lift?

search ya NOOB

[cj]

So does that mean that I can't fit 31's with a 2 inch suspension lift?

search ya NOOB

Where?

[MightyMouse]

How do the available spring kits fit in with VicRoads VSI 8.5 ? Are there issues with legality ?

[cj]

How do the available spring kits fit in with VicRoads VSI 8.5 ? Are there issues with legality ?

I'd be more concerned with how they fit in with the NCOP as that seems to be what Vic is working to now.

[grimbo]

Bible Bound. Top stuff Steve, now if you have any ideas of how to make people read the bible, or search, before asking the same NOOB questions, im all ears .

Good stuff mate

Layto....

you can't do anything. People are lazy and don't for a minute consider the fact that the topic has been discussed before and will have most of their answers already there.

[Tiny]

maybe discussion on

RUF
shackle reversal
extended shackles
drop shackles (ie climax)
leaf removal from packs (spoa)

[Gwagensteve]

maybe discussion on

RUF
shackle reversal
extended shackles
drop shackles (ie climax)
leaf removal from packs (spoa)

I have done RUF, and have photos of a full RUF in progress I can post and I have been making extended shackles for over ten years, So I can definitley do somehting similar with them.

I haven't owned drop shackles (but have done 3/4 elliptic) or SPOA but I am happy to kick off a discussion in a similar way, however, some poeple might disagree with my definition of an "objective discussion"

Steve.

[grimbo]

eaf removal from packs (spoa)

I reckon leaf removal is more of an option on SPUA than SPOA

[MightyMouse]

cj - do you mean the national VSB's ? If so they are read in conjunction
with local regs. So whilst the VSB's are in general more about how to
properly modify and approve the VSI's are sort of outcome driven.

So the VSI one third change "rule" still seems to be in effect in Vic.

The VSB's are an interesting read, surprising what you can do if you do
it properly.

[Gwagensteve]

MightyMouse,

I didn't intend to gloss over your point, it is valid, it's just that there is so much product out there that is in contravention of this code, and so little awareness of it in (certianly in victoria) in relation to lift height that I didn't think it was worth getting into.

As an aside, I tend to think that lower lift heights work the best anyway so it kind of avoids the problem

Also, I think that bumpstop spacing is permitted to keep the 1/3 rule (so long as the car stays uner the maximum height increase so for what I woant out a car that kind of gets around that too.

Steve.

[cj]

cj - do you mean the national VSB's ? If so they are read in conjunction
with local regs. So whilst the VSB's are in general more about how to
properly modify and approve the VSI's are sort of outcome driven.

So the VSI one third change "rule" still seems to be in effect in Vic.

The VSB's are an interesting read, surprising what you can do if you do
it properly.

As far as VicRoads is concerned they have told all the VASS Engineers to work to the NCOP even though they haven't been legislated ....yet, although that is supposed to be happening around the end of the year. http://www.dotars.gov.au/roads/safety/b ... _ncop.aspx

[MightyMouse]

Leaves things a bit confused doesn't it ? As the Code isn't retrospective
then earlier cars do ???

Also a bugger for those who simply assume that because they spent
money with a "reputable" supplier then thrie vehicle must be OK....

An experience with transmission / driveshaft splines with increased heights Steve ?

[GRPABT1]

Why does Gwagensteve hate 3" springs on sierras?

There are a couple of companies making 3" "lift" springs for sierras. they ride like crap and don't offer more travel. Why? Because to hold the height in a spring very short (like the front of a sierra) A) the spring needs to have a higher rate than stock and B) you can't fit a longer shock without fabrication work and C) the range of shackle movement is limited so, the effect is really that the amount of total travel doesn't increase, the spring rate goes up, and because of the higher rate, there is very little chance you will ever reach the bumpstop, so the car ends up choppy and stiff.


Steve.

Ok hear me out before flaming the shit outta me.

Have you ever owned/driven a vehicle with a Calmini 5 inch kit including the (apparently) 3" springs?

Because despite what you wrote and what I cop from every other experienced zook person, my calmini kit still flexes better than stock. Admittedly not by huge amounts but at least a few inches more wheel travel. My zook had stock hight springs/ stock shackles and longer shocks before the calmini kit.

I know that there are better flexing kits on the market and other ways to fit 33" tyres but rule out SPOA and it's associated issues (QLD, steering castor etc) and cutting the shit out of gaurds (personal preference don't flame me) and you're not left with much.

I think the theory on 3" springs being stiffer etc is absolutley true but I think some kits take alot of criticism when it's not all due.

Flame suit on

[mrRocky]

Whats a leaf spring ?