[Gwagensteve]

They’re basically a variation of the teraflex revolver shackle from the early 2000’s, with an added anti inversion bar.

I don’t understand how this product will add much capability to the vehicle. Adding substantial, unsprung wheel travel has a small positive effect on balance as it lowers the centre of gravity a little in cross axle situations can add a little stability, but this advantage vanishes in side angle or dynamic situations*

Additionally these require a fair amount of fabrication to get the best out of. The standard solution is to fit a longer shock by inclining it more which erodes shock function in both travel and flex. Inboarding the bumpstops would also help to transfer more load onto the drooped wheel but by the time you’re cutting and welding you might as well ditch the whacky shackles and just move the shackle hanger forward on the chassis which, with a longer single piece shackle, will achieve the same thing.

*I’ve spent a lot of time driving with Bill Larman’s “wildfing” SII Land Rover. It has a staggering amount of wheel travel, the vast majority of which was achieved with drop shackles, folding spring mounts and loose coils- effectively whacky shackles. It has huge unsprung weight and very wide track. It looks amazing and works very well for very low speed crawling but it’s very uncomfortable and completely falls apart in dynamic situations.

[ChappiesZook]

How does it vanish on a side angle or dynamic situation. And what is a dynamic situation?

[Gwagensteve]

In a side angle the folding shackle doesn’t lower the centre of gravity, it’s effect is either nil or of or if it starts to open up it will raise the COG.

A dynamic situation is when the vehicle is in motion or under power. Drive forces and weight transfer at speed can make folding shackles open up causing bouncing and other unpredictable.

Folding shackles are really just like running shocks that are too long on a coil car or coilovers without enough springs to retain preload. It might look ok parked on a ramp but in motion it’s not a good idea.

[fordem]

My understanding of it, and I'm sure Steve will let me know if I'm wrong, is that droop (or flex), without weight, does not provide traction - so the drop shackles allow the axle to droop further, under it's own weight, so the wheel remains on the ground longer, but without the weight of the vehicle on it, there's no traction, it just spins.

The, so to speak, aim of the game, is to have traction so you can keep moving, flex without traction is nothing.

[ChappiesZook]

Ok so what I’m understanding is that, in slow crawler-like situations they are ok, but on extreme angles the shackles don’t do anything and have the slight chance to open up, potentially.
Also that situations that require more momentum/speed, the car has a chance to bounce more and have unpredictable tendencies
Would I be correct on this.

I wanna stress that this car will be a “low and slow” only car. Pretty much 0 Sand. Highway yes but only to get where I’m going. (Buying trailer soon) I do Mainly rock crawlin, rock steps, creeks, with a few angles, hills etc. I already have 2” shackles so the legality of drop shackles is somewhat irrelevant.
I mainly wanted to know the safety of rear drop shackles in the type of terrain I drive.

I wish I could show you they type of terrain that I would be driving for better idea.
I’m assuming that you have probably heard of pistol gap?
That’s in my backyard. That’s the kind of terrain I wanna drive. But more of the bonus lines.

[Gwagensteve]

The bigger question rather than “are they safe” is are they helping capability? I’m going to say 100% no on the rear in real terrain. When the car’s capability is on the limit will always be on big angles. Watch a swb Sierra on hard terrain- the rear is doing next to nothing. It’s all happening in the front. That’s what’s keeping the nose down and the car planted because when the car is climbing the rear is loaded up by weight transfer. The rear won’t droop. Even my car doesn’t work the rear hard when climbing. Concentrate on getting the car low and stable. You’re going to need to cut the guards to get the bump stop spacers out of the front. This will let the front sit lower on the obstacle which is worth way more capability than a couple of inches of rear droop at the risk of having the high side start to unload on angles.

Again, I’m sure Beery’s car would drive stuff you wouldn’t believe with minimal wheel travel but very trustworthy suspension.

[ChappiesZook]

Ok I’m back! After lots and lots of thunkin’ (and a stuck transfer drain bung) I’ve decided to listen to your advice and change a bit of my setup


My new plan is to redrill holes in my the front spring hanger 10mm back to bring the front back to reduce the amount of shock angle (as it’s close to fouling on the bumpstop mount) and allow me to run a shorter shackle as I hate the ride and angle of the 2” extended shackle with the 50mm RUF. It should also help it contacting the front side of the guard when flexed up.
I have contacted my local fab crew and they believe they can weld in shock towers for me and blue plate them so I can’t get done by the po-pos. This will allow me to run 0 bumpstop spacer.

I am also going to get my guards chopped, As I have no welding experience I’m going to get a shop to do it for me I reckon.
The question is how far to cut. Like I said I wanna run 31” tyres, and have no restriction on uptravel, so I’m thinking cutting maybe 50-60mm out of the guards? What do yous reckon?
Or should I just send it and cut just above where the top of the WT Flares touch the body, and weld it across to the inner flare? I want to keep inner guard to protect engine bay and motor.

Cheers

[Gwagensteve]

The only way to do this in my opinion is to choose your tyre and rim offset, set the car up with a single leaf pack and cycle the suspension. You can then size shock length and cut the guard to clear your tyre.

If you do it by guesswork you’ll most likely get it wrong, which is a huge hassle if you’re paying someone to do it.

Rim offset and tyre choice is critical for shock mount placement. It’s very hard to keep the tyres out of the shock mount.

[ChappiesZook]

I’m running 31x10.5r15 Comforser CF3000s
On Black Dynamic Sunraysia 15x8 -25

So, flex max uptravel, flex max down travel, then go from there?

It may be stupid idea but If I’m running a 50mm bump spacer, would I then remove 50mm from the guard?
Just my thinking.

[ChappiesZook]

Also Gwagensteve,
I have a question
I have seen photos of a white Zook around called trolley tug and I believe it is/was your rig. The photos of the flex it achieved with leafs is mind blowing. Woudl you mind sharing the build and component specs with me? Cos it’s frickin sick as. That’s the kinda travel I want ahaha

[Brenno]

https://auszookers.com/forum/viewtopic.php?f=4&t=14025&hilit=trolley+tug

Here is the build thread.

[ChappiesZook]

Unfortunately I can’t view any of the images, so it’s a bit hard to understand the finer details. Cheers for the link though

[Gwagensteve]

All the photos in the trolley tug thread were deleted in the great photo bucket ransom debacle. I do have them though and the key ones (and some others) are here.

I built the trolley tug with its owner. we started building it 19 years ago. It's still around, it's now owned by a young member of the Vic club and is now camo. It's not registered.

It didn't achieve what I'd call "mind blowing" flex but more importantly, many of the finer details weren't properly resolved and they compromised the car. Some of this is because we don't know better and some is because we build it much more quickly than a "full" build.

It was refined a bit when it was resprayed grey but the major compromises were still there.

In contrast GregC's car was built though the same period but much more work was put in to remove compromises. However, they're both products of their time and I wouldn't build a car like either of them now.

Here they are side by side in 2005 with the chassis work on GregC's car complete and the trolley tug about to be started.





Here were the principle issues. I'll separate out those that are shared wth both cars and those that were unique to the trolley tug.


Both cars were RUF on derated OME leaves No issue there.

Both were set up on OME N76 shocks.The shocks are a compromise in themselves. We chose them because they're long and very soft. The problem is they're too long (about 11" travel) and that means the springs can get forced into overextension which fans the packs apart and makes them easy to damage. Also, the length means they don't fit under the floor in the rear and are very hard to build mounts for.

Both cars were built with 50mm bumpstop spacers and 50mm body lifts. This was seen as the only feasible way to run 35" tyres. This means the cars have to sit taller than ideal. GregC has done some work to lower his car as much as possible by cutting down the spacers in the front.

The chassis extension on both cars was too long. this put the shackle too vertical which added more ride height. I think we did this so stock shackles could be used but it was 20 years ago so of course we ran long shackles too.

On the trolley tug we didn't inboard the front springs. This compromised steering lock heavily and hurt roll stiffness. To try and rectify the steering lock issue, we ran heavily offset rims which pushed the track width out too far and made the car a pain - steering load and kickback were heavy and the car didn't fit where narrower sierra's could fit. It also never had power steering.

It was later converted to G16B Baleno and three speed auto (this was when it was grey). Michael, the owner is a freakishly talented driver and the car performed very well for its time but it was a bit of a bear to manage for some of the reasons I've explained.

Much later we converted the rear to radius arms and a full float axle to get rid of axle wrap and hopping which was breaking axles (another problem with a very big heavy tyre on a SWB with soft leaves) but the car only did a couple of trips like that before the rego lapsed and It was laid up for many years.

For reference, it had the same travel as GregC's car, just in some photos it looks more dramatic because it had/has no front bar



When first set up



Look how much ride height it has. Madness.

In contrast, here's Greg's car with the springs underslung. It's much cleaner but you can see the shackle angle is way too much and the extension could have been much smaller.







With the G16B conversion and auto. It was basically "complete" at this point and did quite a lot of trips.

This might be the photo you're referring to:



This was on it's first trip. I agree it looks like it has loads of flex here but it's a little it of a trick of the angle the photo was taken on.

Here's Gregc's car flexing similarly.



For reference, here is a more recent photo of GregC's car on 35X10 KR2's. he's worked quite hard to get it lower working within the constraints of the original build, but it now has very little compression travel which hurts performance at speed.



Don't get me wrong, the trolley tug was an effective and fun car, but twenty years of development means it's a long way from state of the art now.

[Gwagensteve]

Another point on this photo:



That's sitting on 33 9.5 BFG's and the guards had not been cut at that point. I recall there was some very light scuffing on the inner guards but that's all. Consider there's 100mm of body lift and spacer keeping the tyres away from the guards which means the car is sitting 100mm taller on the obstacle than it really should be. that's really evident in the rear where that 33 isn't tucking up into the guard at all.

That's my point about this being a tall car. Sure, with the weight and width of the Q78's on it wasn't unstable, but could have been much better.

[ChappiesZook]

Hey guys I’m back. Cheers for sending through the photos gwagensteve, it’s given me a good idea of what to do. I want a build very similar to it so any and all info is appreciated.

So in my absence I’ve been playing around with some suspension, removing rear leaves etc, and driving. Went 4wding with my local club on the weekend and I was amazed at how capable it had become. We also had a bit of fun on the clubs RTI ramp.

I know that RTI scores aren’t everything, but it did give me a good idea on travel etc. and it looked cool. Drove front up and drivers side wheel on the ramp. My first attempt I got a score of 662 (661.9). I’ve been led to belive that it’s not a great score but not terrible.

I had a second go just for fun, and my mate jumped on the rear drivers side above the wheel and it made me go so much further it’s not funny. I’ll try and attach a photo of how far it got up. I was incredibly impressed. Towards the end it did lift the front by maybe 50mm, but I’m absolutely stoked. It Went so far that the rear wheel was almost touching the ramp. I reckon it would have scored close to 900.

I ask, what do I have to do to the rear to make it perform and flex like that WITHOUT having someone climb on the side of it? If I can achieve that level of flex and travel without needing someone to jump on the rear, I’m happy with it. I’ll stop changing suspension and leave it like that.
Cheers

Attachment:

IMG_2136.jpeg

[Gwagensteve]

The obvious answer is less spring rate but that's normally not practical.

What you've found is the difference in roll stiffness front to rear. The rear has wide spaced leaves for stability carrying loads. Pulling the leaves inboard ao they are under the chassis like a NT Sierra helps but it's marginal. You can also play with moving the spring hanger forwards and running a longer shackle - this will generate more droop, but the fuel filler neck will be in the way and it's a fabrication heavy job for a small and not entirely predictable return. We did do this on GregC's car as part of in boarding the rear springs. A note though, this increases squat which causes more rearward weight transfer on climbing.

In reality it only makes a tiny bit of difference off road - Ideally, you want the rear of the car to be planted when climbing because having lots of rear travel can make the car unstable on big compound angles unless it's very well controlled, which is hard with leaves.

Also RTI "scores" are really meaningless between vehicles in my opinion - a car with really , really awful suspension might ramp really well. However, there is a way to make the RTI a way of assessing whether the suspension is working well or not.

Use an angle finder on the front axle housing when the car is fully flexed and read the angle, and then compare that to the angle the body is on. Ideally, when driven forward up the ramp, you want the front to be flexing 55-60% of the total travel - so if the body is at 20˚ the front axle might be at 45˚ This is what a balanced car feels like.



this is Joshyboy's car and mine on a 25˚ish RTI ramp. Both cars are pretty well balanced - we both have outboard coils on the rear, Josh is radius arm front and rear and I'm links so I have more total travel but Josh has more durability and ease of parts replacement. Both cars a closer in capability than you'd think. mine looks a bit funkier on big obstacles but both cars are balanced and get it done.

for reference here's Bill's Wildfing driving off the end of the same ramp.



Obviously, big mismatches one way or the other imply a car that will behave poorly off road - if the front is only dong 15% of the total flex, the car will follow the nose and will be very unstable when climbing (and feel scary) - if the front is doing 80% of the flex the rear needs work.

This measure is completely irrespective of the total flex - it's just a measure of how equally balanced the suspension is when climbing. which is when the vehicle's behaviour is most challenged.

of course you can repeat the experiment by reversing up the ramp and this will force the front to work harder but we don't tend to reverse up obstacles.

*PS - yes, my LHR tyre is an insie bit off the ground. This was largely a result of putting the car in park and drive load coming off the suspension causing the front to relax and lifting the rear. My car rises and falls about 70mm in the front right when it's in or out of gear when in low range. That's low gearing and a torque converter for you.

[ChappiesZook]

Hmm I see. That explains a lot thanks. Yea see when I did it I got a fair distance up when driving up, but when I tried to reverse up, it was dismally unimpressive. The front is working way harder than the rear, which would make sense seeing other than derating springs I haven’t really done much.
Definitely needs some more work as rear tyres for some reason doesn’t touch bumpstop or the inner guard it gets close but gets stuck on something. Maybe shocks are limiting up travel?
As you said though I don’t wanna make the rear too crazy cos it gets spooky when climbing.
Once I put my 6 point in it that extra weight in the rear should help too.