[Tawatree]

Hi all, I've got some confusion with the springs that I've got out of 2 different vitaras. If I've added the picture correctly, the left spring is from the rear of a swb and the right spring is from the rear of a lwb. The left spring has a longer free length by about 10mm, less wraps and a bigger outer and inner diameter. Both have the same wire diameter (12mm) and both seem to fit the hats and seats but just wondering if these are what I've been told they are.

Cheers

[Gwagensteve]

I don’t have access to them right now but I have a stash of vitara rear springs, most of which are identified so I can potentially resolve this for you.

The diameter thing is confusing though. Vitaras all have the same diameter rear springs. GV’s have slightly larger diameter springs (from memory)

What are you trying to achieve though? They’ll be pretty close in rate and swapping rear springs is a very quick job.

[Tawatree]

Cheers, the diameter is what was most confusing to me, and the fact that one should be from a lwb and one swb but they are very similar. They are to fit my beams coily, just to mock up at first and I'll probably swap to longer ones afterwards
I can get the free lengths and diamaters tomorrow

[Tawatree]

Left spring- 115mm OD, 338mm long (from swb)
Right spring- 107mm OD, 325mm long (from lwb)

[Gwagensteve]

Ignoring the diameter for now, I’m still trying to work out what you want to achieve. You’ll need to determine the springs working range, you can use the stock vitara measurements to confirm this. Length of spring at full compression is the critical figure. Mock the axle up at full compression and then fit the spring and check ride height, adjust the top spring perch to tune ride height. The SWB rear spring is the softest available so everything else will provide more ride height. Vitara rear springs don’t have all that much travel stock. And if you run a significantly longer spring you need to consider block height (spring bind) and ride height. My front end would have a similar weight to what your planning and I run a calmini 3.5” lift vitara rear spring but if basically binds on full articulation. I run 50mm of compression travel at ride height and calmini rears are good for about 11” of vertical travel, which is a lot for a single coil.

This is also a problem with the JB jimny front end. Soft long springs get very very close to bind.

[Tawatree]

This is my first time setting up coil suspension so I wanted a frame of reference with a spring that I know the rate of, mock it up and then figure out what length I want to run and if I need to change spring rates. I would have assumed that my front end would be heavier than yours due to my engine. What rate are your calmini springs?

[Brenno]

I have GV springs in mine which has a ca18 cast iron jobby. Probably similar weight to yours I would imagine.

Half way down the page gives some reference. https://auszookers.com/forum/viewtopic.php?f=4&t=54112&start=150

[Brenno]

Oh, and please start a build thread!

[Tawatree]

Cheers, I thought gv springs didn't fit because of the coil size changing at the top? I'll deffinately start a build thread as soon as I get some time

[Gwagensteve]

I’ll post in more detail later but SWB rear springs have about 120lb/“ rate. I have lots of steel in my car and high mount in the front. I don’t expect it’s much lighter than what you’re planning.

[Gwagensteve]

I should have some measurements on my SWB Vitara rear springs later today. You can enter the measurements of the springs you have into an on-line spring rate calculator, this will also get you in the ballpark. Starting your mockup with a SWB vitara definitely makes sense as you have lots of options to add rate and height later, just not travel.

Ride height is easily tuned - it's really just where you weld the spring hat. The issue is that if the spring doesn't have enough length or, doesn't have enough rate, you'll have no travel between ride height and full compression. You can do some of this with a tape measure and a spring rate calculator, but there's also some trial and error in there too. I had to move my spring hats to lower the car after my initial calculations/measurements during my last build.

There are whole units in Mech eng courses on this stuff, but the #1 thing I see people doing with coils is assuming they have lots of travel - they don't. It's rare to see a coil for a 4WD application with more than 250mm of travel because high travel requires extremely long springs which can't be easily packaged, so to try and get the very most travel out of a spring design you need to ensure it's close to bind at full compression, or you're just wasting the spring. The bind point or "block" point changes with different springs. This is why lots of common 2" lift springs for vitara rears are SHORTER than the stock spring. If you make the spring longer with, say, an extra turn of wire, that extra turn makes the block point of the spring taller too. when you're trying to fit a spring into an existing design, that means it will block before the axle compresses the bumpstop, which makes the ride very harsh and can break the car. Therefore to get the rate right (thicker wire, which also makes the spring taller when blocked) and the number of turns right, the outcome is a shorter spring at free length.

If you're designing from scratch you can work around this a bit, but only within the bounds of the physics of spring design and the hard points the car gives you.

My first go at my coil front suspension had the car set up with vitara rear SWB springs to get the ride height I wanted. However, because of my inverted radius arms, my car was running the equivalent of 2" of front bumpstop spacing, which meant I had very little compression travel at ride height. I swapped to 2" lift springs which helped, but ultimately, the car was taller than I wanted and the springs would go loose on flex. I was a pretty compromised setup, mostly because of the inverted radius arms eating up compression travel - I was wasting 2" of spring travel

My revised setup put calmini 3.5" rear springs (100lb/") behind the axle housing to keep the top of the spring hat low and out of the reach of the tyres. I have full compression travel as I removed the radius arms, and I use all the safe travel of a 12" shock. However, to give you an idea of how fine the tolerances are, to correct Sierra lean I run a 20mm spacer on the RHS, and this pushes the driver's side spring to block at full compression. I can't avoid this, the only solution would be a spring with a slightly higher rate with a shorter block height, which would a custom solution and I suspect not easy to design.

Here's some photos.

This is setting up my current configuration bar in 2018 . You can see this spring is very, very close to block height. the 20mm spacer on the driver's side results in bind.



Driver's side at full droop



This works very well but that's not just isolated to the springs - I totally revised the suspension as part of this rebuild.

Here's the old setup, something closer to what I imagine you're planning.

This is a stock Vitara rear spring at ride height using a factory Vitara spring seat (from the rear axle) and a factory vitara rear coil hat. Whilst there's no winch in place (or front clip) ride height is still pretty much ideal as it would come down once complete.



My problem, though, was the flipped radius arms. Once complete and setup, the result was this:



I rapidly had to swap to a 2" lift spring, and this photo is at ride height. You'll note There's about 150mm from the axle to the chassis, but the bumpstop has been spaced way down inside the coil and I have about 2" of usable compression travel, even though about 4" of shock shaft was showing. Whilst this was due to my radius arms, there could be other factors (tyre clearance, sump etc) that mean you need to add bumpstop spacing after you've set your mounts in place and it really kills the effectiveness of the suspension.



This was the solution for the first phase of the front end.

I put Sierra front bumpstops on the chassis which contacted the radius arms and I ran limit straps to stop the coils falling out. Ultimately, it was OK to drive but I wasn't really getting very much travel - not much over 6". My life would have been much easier if I hadn't flipped the radius arms and ran a stock spring with a much shorter shock. What I did is very typical of people swapping to coils - run a shock that's waaaay to long, the coils go loose and compression travel is limited by other compromises.


*A quick note on the calmini Vitara rear springs I use. They're weirdly designed. They have an incredibly low rate, 100lb/" (I calculated this and then confirmed it when I weighed the car) and they're so soft they're almost useless in a vitara. Calmini also design them to bind at full compression in the back of a vitara which is, er, "unconventional" at best. THey're very, very long and have quite a lot of turns for their length, which makes the rate low but also makes the block length tall. They will travel about 11" though, which is crazy for anything designed to fit in a standard vehicle. Unfortunately, Calmini products are basically vapourware and I don't believe they will sell the springs alone without all the junk vitara bracketry that comes with them. It took me years to accumulate a set.

[Gwagensteve]

OK, got access to my stash of springs yesterday and made some measurements.

There appears to be more nuanced variants in stock springs than I was aware of. Also, Suzuki appear to mark their springs in the same way Land Rover do. There is a very good understanding of the Land Rover colour code, I suspect that's not the case for Suzuki.

This is what I have:

SWB Soft Top Rear (Maybe, not identified) This spring has a blue and white stripe.

10.8mm wire
Free length 325mm
OD bottom 104mm
OD top 94.5mm
7.5 turns of wire

SWB Hardtop Rear (Maybe, not identified) This spring has a green and white stripe

11.4mm wire
Free length 310mm
OD Bottom 105.5mm
OD Top 96.5mm
8.8 turns of wire

LWB rear (Confirmed, I removed it from the vehicle and tagged it) White and two grey stripes

11.7mm wire
322mm free length
OD Bottom 106.9
OD Top 96.5
8.9 turns of wire

Generic 2" Vitara lift spring, yellow. I think it was tough dog or something.

12.2mm wire
340mm Free Length
OD Bottom 106.2
OD Top 94.3
11 turns of wire

Another generic aftermarket spring. Not sure of application, assume Vitara rear or Jimny front (They're very similar) I'm suspicious it's jimny front because it has a "PS" tag on it, I don't believe rear springs are different side to side on the rear of a vitara.

12mm wire
360mm free length
OD Bottom 105.7
OD Top 94.2
9.2 turns of wire

My observation is the last spring probably has the most travel, the yellow spring probably the least.

I haven't run these measurements through a rate calculator. One small complication of them is they request the # of "active coils" It's possible that as the bottom 1/2 coil sits on the seat it might be wise to deduct 0.4 or something like from each coil to try and achieve a "true" rate, but for the purposes of comparison that won't make any difference.

Here's the coils in order, I didn't photograph the first one.

[Gwagensteve]

for reference, this is how bananas the Calmini rears are compared to the 2" springs I specced above.

How Calamity decided that these would fit with no bumpstop spacing is beyond me. They would block so hard Calmini commented that they would "settle" after use.

Perfect example of people buying a product because it exists regardless of how terrible it is. Happily for the me the springs are grouse though, for my application if not actually for a Vitara rear.

[Tawatree]

Wow thanks for all the info, that's great. All the photos of your builds are really helpful too. I've read through your build posts a couple times but lots of the older photos are gone so it's great to see some of them. I'll compare the springs to mine and see if they match anything. Cheers

[Tawatree]

Have started a build thread now.

[rob_macca67]

Curious here... has anyone considered the GV XL7 Rear Coils?

Dobinsons sell a HD version with the following Info (can't find spring rate though):

Wire Thickness: 14mm
No of Coils: 10.5
Free length: 390mm
In-Car length: 300mm
I/S Diameter: 92mm (bottom)
I/S Diameter: 62mm (top)
O/S Diameter: 120mm

[Brenno]

I have a feeling I put XL7 coils in at some point. I think the standard ones have 2 blue dots.

[rob_macca67]

Brenno wrote:

I have a feeling I put XL7 coils in at some point. I think the standard ones have 2 blue dots.

Believe or not but supercheapauto have a Black Friday sale that finishes today. They have those XL7 coils at almost 50% off for today only (if that helps)