Dobinsons 3 inch Progressive / Flexi coil review (7 Viewers)

[half k cruiser]

Am I correct in thinking that progressive and dual rate springs are not really made or good at carrying a heavy load? My truck has back. I carry 2 kids, a big dog, a wife, 3 cans of fuel, propane tank, labs bumper, jack, rear tire, etc. I have to have load carrying capacity. On top of that I tow sometiimes as well. I currently am running j springs front and rear.

They can be load matched similar to a linear rate spring. For instance when I spoke with the Dobinsons rep he told me that the rear springs I was ordering were rated for an additional 100kg of load. Essentially once you collapse the ride rate the load rate is going to take over. If you look at Trail Tailor's offerings you will see that he is bringing in dual rate coils that have ratings anywhere from 0 on up to 600 lbs of additional load. If you are interested it would probably be best to just call or email one of the vendors and they could help you decide on the appropriate springs for your application.

 

[AutoCraft Aus]

Adam is on the money.

As for load, we do dual and linear in extended free height for 440 lb intermediates right up to 1980 lb constant load and the way we design the dual rates is to go softer rate a little and taller free height to maintain good unloaded ride.

They only way we were able to do this long term successfully was to taper the wire, and ensure they came off the mandrel in spec and could not be retempered to meet spec if outside it once they had been scragged. [those that dont make spec go to scrap]

Otherwise with all the testing we dd with Aus grade materials we saw breakages right where the active to dead coils flex, and/or sagging within months.

We went through 9 designs to get that right. We have coils from 2002 still going strong in these designs with tapered wire.

Not saying these will do that, but just i my experience what I have found with dual/progressive/linear coils.

 

[Qball]

These springs sure look good! I really like the idea of 3 inch springs and definitely see these in my future. Btw where did you get them?


But I do have a question for everyone on the dual rate and progresssive spring. I had OME factory height springs and now TJM progressive springs. And when they are compressed by the weight of the cruiser the dual rate/progressive part of coil always looks collapsed or touching. To me all that does is being a spacer instead of spring. And from pictures at the beginning of the thread the softer part also pretty much collapsed. So how does the softer part of spring work when it's fully compressed under normal weight? Or how does it provide softer suspension to absorb smaller bumps when it's always being a spacer? I assume only time it would uncoil it when whe spring is un-weighted but what good does that do for small bumper when driving?

Sorry for the noob question.

 

[lumbee1]

Where do we get these springs and what is the price? Brown Santa is bringing Fox shocks but I would like to replace my coils as well.

 

[AutoCraft Aus]

@Qball The dual rate pr progressive is to smooth out the feel from empty to loaded, so if you car is heavier or loaded the softer rate closes up, to get to the firmer rate.

Thats what it designed to do.

Also when you look at the softer rate it may look closed, but a small gap per few coils means softer for the very first part of travel too.

 

[half k cruiser]

But I do have a question for everyone on the dual rate and progresssive spring. I had OME factory height springs and now TJM progressive springs. And when they are compressed by the weight of the cruiser the dual rate/progressive part of coil always looks collapsed or touching. To me all that does is being a spacer instead of spring.
.

The easiest way I can think of to explain it would be imagine you put that spring on a table and put your hand over it. Now imagine you have the power to press down on it with your hand and cause the top coils to collapse down onto themselves. Even if the coils were touching, they are still pushing back against your hand. There is still a force there causing lift.

Where do we get these springs and what is the price? Brown Santa is bringing Fox shocks but I would like to replace my coils as well.

@David Otero is the guy you want to talk to. The 3'' flexi coils run $250 a pair, which to me was more than reasonable.

 

[Qball]

The easiest way I can think of to explain it would be imagine you put that spring on a table and put your hand over it. Now imagine you have the power to press down on it with your hand and cause the top coils to collapse down onto themselves. Even if the coils were touching, they are still pushing back against your hand. There is still a force there causing lift.



@David Otero is the guy you want to talk to. The 3'' flexi coils run $250 a pair, which to me was more than reasonable.

Thanks, do you usually have much in your rig? I run mostly empty but do load up some what when going on a trip. How does it compare to OME when it comes to firmness, and of course which OME? How does it do on bigger and harder hits?

I LOVE how my TJM rides on the road, down right amazing paired with fox IFP. But I do tend to blow through travel a bit too quickly on the larger hits so I don't mind firming up the suspension on the second half of the travel. King's shocks supposedly was working on a dual stage shocks for the 80 but that has been a while. Once I finally get my dirty little hands on those shocks I might seriously look at these springs.

 

[Qball]

@Qball The dual rate pr progressive is to smooth out the feel from empty to loaded, so if you car is heavier or loaded the softer rate closes up, to get to the firmer rate.

Thats what it designed to do.

Also when you look at the softer rate it may look closed, but a small gap per few coils means softer for the very first part of travel too.

Thanks, I do see a little gap on the last coil of the softer coils so I guess that's where the softer part come from. Although I'm still wondering why the rest are simply spacers. Oh well.

 

[half k cruiser]

Thanks, do you usually have much in your rig? I run mostly empty but do load up some what when going on a trip. How does it compare to OME when it comes to firmness, and of course which OME? How does it do on bigger and harder hits?

My truck has front and rear bumpers, sliders, rears swings with spare tire and 60'' hi lift, dual batteries. That and a box of tools / roadside emergency gear is my constant load. On trips the weight is obviously increased with passengers and extra gear, maybe another 600-800lbs ? I will be testing that out soon enough.

With my everyday load they are handling bumps and road corrugations better than my 850J / 863 setup. I am very interested to see what they will do when I get it off road and start running it over rocks and washboard. As I mentioned in a previous post the big hits are firm, but not jarring like they could be with my old setup.

Thanks, I do see a little gap on the last coil of the softer coils so I guess that's where the softer part come from. Although I'm still wondering why the rest are simply spacers. Oh well.

They aren't really. It requires weight from the vehicle to compress them down that far. Whatever amount of weight was required to get them down is "sprung" by the coil even if they are stacked on top of each other. If you could put a camera on them and go around a corner you would see the following.....

- the outside coil would compress further and there would no longer be those playing card thin gaps between coils. Then once the gap is closed up the next set of coils (the ones with further spacing between them) would start to compress down.

-the inside coil would begin to expand upward. The playing card thin gaps would increase in size and look more like they did before installation. This is due to the fact that they are still providing lift, therefore still capable of expanding.

If the top coils were simply a spacer then when you cornered they wouldn't compress or expand, they would just stay the same.

 

[GW Nugget]

Thank you @half k cruiser for the right up. It looks like they need to settle in a bit more. Please visit back & post your finding in a few weeks.



I'm not a suspension or coil expert but there seems to clearly be two types of dual rates now. Ones with same wire size for entire coil & a tapered kind. I also noticed there are stacked & open types. These will act differently in the transition between rates. One will be more pronounced the other do I dare say a more progressive feel.

I can clearly feel when my rig goes from one rate to the next. Mainly because my rig is light in terms of most others. I know for sure at ride height it's sitting on the 160 pound top rates because I can slide a business card through the stacked section of coils.

Any way... I like the Slinkies best simply for ride & handling, but most of all they don't unload while transitioning from side to side & even more so on down hill off camber turns. My guess is they push upward less in the last few inches of exstension.

 

[Box Rocket]

Thanks, I do see a little gap on the last coil of the softer coils so I guess that's where the softer part come from. Although I'm still wondering why the rest are simply spacers. Oh well.

The answer is traction at the limit of travel.
I'm going to use my Slinks as a visual aid. Here are the front Slinkys just before they went on my truck next the OME J springs that just came off. Much taller free height with the Slinky, but essentially the same size lift at ride height.


What that means is when a linear rate coil reaches the max amount of droop, there is no longer any pressure from the spring pushing the tire to the ground, which means very little traction.

With the collapsed coils when it reaches the point that the linear coil hit its max droop, there is still more travel to be had from the spring and more importantly, downward pressure from the spring to the tire on the ground, which means better traction and more travel.

Here's the Slinky at full droop with no limitation from shocks or anything else. We still had to force the shock into place. My old OME spring would have been hanging free of the coil bucket by probably 6".


Here's the same spring at ride height just after install.

 

[Qball]

The answer is traction at the limit of travel.
I'm going to use my Slinks as a visual aid. Here are the front Slinkys just before they went on my truck next the OME J springs that just came off. Much taller free height with the Slinky, but essentially the same size lift at ride height.


What that means is when a linear rate coil reaches the max amount of droop, there is no longer any pressure from the spring pushing the tire to the ground, which means very little traction.

With the collapsed coils when it reaches the point that the linear coil hit its max droop, there is still more travel to be had from the spring and more importantly, downward pressure from the spring to the tire on the ground, which means better traction and more travel.

Here's the Slinky at full droop with no limitation from shocks or anything else. We still had to force the shock into place. My old OME spring would have been hanging free of the coil bucket by probably 6".


Here's the same spring at ride height just after install.

Ah that makes good sense. So at ride height the top coils are simply spacers until suspension unload and give more and better droop. But that still means at ride height it's pretty much single rate which is kind of my original question. At normal ride height it appears that my OME and TJM are for the most part single rate springs. Funny thing is the OME factory height springs doesn't give much droop at all. TJM does give additional droop compare to similar OME but not really by much.


Basically I'm looking for spring that will increase spring rate a bit more 1/2 way through the travel so on larger hits I don't bottom out as much. I'm also looking for dual stage shocks that will do that, we will see what I find eventually. So far the slinky springs appear to be the only one that comes close to what I am looking for, maybe these dobinson springs might also do the trick.

 

[AutoCraft Aus]

That last pic tells the main story too Adam, very well for the tapered dual rate.

Theres a small amount of progressive rate in that last wind before the secondary rate, where it gives that little bit of softer rate before it goes to the full hard rate, but not that much the car feels "tippy" or unstable, with the shock package especially.

The softer rate open as you say for traction, but also for stability, when the vehicle is stretched out and near its limits, you have a softer rate exposed, which wont upset the car or make it move around corner to corner or side to side as much, because of the softer rate, but it will keep the tyre pressed into the traction surface. When your on the washboard roads, bad back roads etc though, you have a small amount of give as it increases rate a little for better on road ride. We also tend to go a slightly softer rate on the heavy one, but a slightly taller free height, so we can have a better unloaded ride quality as well, but the spring will sit at the required height at the rated load.

They are important factors in heavy touring and overland trucks to ensure they keep the rubber side down.

This pic illustrates that well I think, for anyone who has seen Cruisers drive across this, car rocking, left front wheel in the air, bumper dragging, Woody has stage 4 slinky long travel intermediate package in Gretchen for afew years now, and in the pic you can see how theres softer rate to keep tyres on rocks, and enough travel to keep them there, and as the car comes back onto the coils and they compress, the coil rate increases to prevent momentum getting a run over the suspension.

Yet you can go bombing in the dunes, being chased by a U4 truck, loaded, windows up, AC on, drink in the cup holder, smiling from ear to ear, when you have your 80 "off the leash "

 

[Box Rocket]

Ah that makes good sense. So at ride height the top coils are simply spacers until suspension unload and give more and better droop. But that still means at ride height it's pretty much single rate which is kind of my original question. At normal ride height it appears that my OME and TJM are for the most part single rate springs. Funny thing is the OME factory height springs doesn't give much droop at all. TJM does give additional droop compare to similar OME but not really by much.


Basically I'm looking for spring that will increase spring rate a bit more 1/2 way through the travel so on larger hits I don't bottom out as much. I'm also looking for dual stage shocks that will do that, we will see what I find eventually. So far the slinky springs appear to be the only one that comes close to what I am looking for, maybe these Robinson springs might also do the trick.

Sounds like you need better shocks, not necessarily better springs, although there are better spring options too. The right shocks will accomplish what you're looking for.

 

[AutoCraft Aus]

Sounds like you need better shocks, not necessarily better springs, although there are better spring options too. The right shocks will accomplish what you're looking for.

Thats the key here you have hit the nail on the head I think Adam.

Its the springs job to suspend the vehicle at the height required, its the shock absorbers job to control the movement.

 

[Qball]

Sounds like you need better shocks, not necessarily better springs, although there are better spring options too. The right shocks will accomplish what you're looking for.

I need better shocks for sure! But from my experience tuning suspension on my mountain bikes I need both to achieve best result. A good shock can help crutch under rated or over rated spring setup but #1 rule of suspension tuning is to have the correct spring and then control/tune the springs with properly matched shocks. So I'm looking for properly matched dual rate springs to my needs(weight and speed) and then proper dual stage shocks matched to those springs.


Unfortunately it obviously won't be cheap. And I obviously can't leave good enough alone.....but isn't that the MUD way???

 

[Qball]

Thats the key here you have hit the nail on the head I think Adam.

Its the springs job to suspend the vehicle at the height required, its the shock absorbers job to control the movement.

I agree to a degree, proper amount of sag(not necessarily just the ride height) is key to match spring behavior to the suspended subject. Amount of spring can compress at ride height is for up travel or the bumps, amount of sag or springs already compressed is for down travel which is for dips or back side of big bump. More the better of course(just check out those Baja trophies trucks) but our rig has obvious limitations.


But as speed increases the amount of force need to be absorbed for the same size bump will increase exponentially. This is why i want dual rate springs, softer rate for normal driving/small bumps and when that big bump sneak up on me bombing down trails I won't bottom out and lose control. It's for safety, at least that's what I keep telling myself.

Rumor has it kings will come out with relatively affordable dual stage shocks so I'm shopping for springs to get ready whenever they decide to finally release them.

 

[Qball]

@Qball find someone with the Slinky springs/shocks and get them to take you for a ride. Do the same with as many different dual rate spring/shock combos as you can find. (hit up a local club if you haven't already). You'll find the ones that works best.

That is the plan, do you know of anyone that has slinky springs at least in LA or sacramento area?

 

[GW Nugget]

That is the plan, do you know of anyone that has slinky springs at least in LA or sacramento area?

There is someone that just posted in the week end 80 thread that in LA & I live in Central Cal near Fresno.

 

[AutoCraft Aus]

Sounds like you just need to get to Cruise Moab then