Torsion bar ifs - How do I get more flex & droop?

Springs, shocks and all things between your chassis and diffs
jacnden
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Torsion bar ifs - How do I get more flex & droop?

Unread post by jacnden » February 20th, 2014, 6:41 am

hi all
a couple of questions for those that know a bit more about suspension than me. i am trying to get the most out of torsion bar ifs that i can.
the bars are wound up about 40mm . i have about 13mm diff drop, cant go anymore without modifying the crossmember. i have about 70mm droop when wheels off the ground. if i take one shocker off there is only 12mm more travel on that side till the upper control arm bottoms out and the cv's are at an extreme angle

what would those calmini upper control arms achieve if i fitted them? would a ball joint reversal reduce the cv angle? would dropping the diff more achieve anything?

some of you may know my car is a great wall but the front is very similar to RA rodeo and its all probably relevant to any torsion bar ifs. very close to the limits of what i can do but still trying to get a bit more out of it.
any ideas?

mydmax
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Re: Torsion bar ifs - How do I get more lift?

Unread post by mydmax » February 20th, 2014, 9:07 am

The upper control arm stop is there to catch the arm when or if the shocker breaks and doesn't hold the arm as it get to the full down position.

If you only have 70mm as the droop factor then when on road at fast speed and you go over rises the wheels will often leave the ground and then there is no steering, braking etc, if that situation gets away from you then it may cause an accident. That is why 1/3 of all travel is noted as the legal minimum for droop amount..

A ball joint reversal, I suppose you mean the top one, will not have any bearing on the CV angels as it is directly the result of the lower arm and diff position.

When you lower the diff that has a beneficial effect for the CV's, but if the diff is brought down a lot then IT is the low point.

I find it amusing to see pictures of monster and other mods and although you need a ladder to get into the cab the diff is still down low. Sort of defeats the purpose.

jacnden
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Re: Torsion bar ifs - How do I get more lift?

Unread post by jacnden » February 20th, 2014, 10:21 am

thanks for the reply , i guess the diff drop enables you to wind the bars up more to fit bigger tyres to get more clearance. i cant really fit bigger than i have now, nearly 32's , so that rules that one out
what would be normal droop on stock torsion bar suspension be, and on one wound up?

so the ball joint reversal only gives hieght and not downward travel, is that right. and i guess those modified upper control arms do the same?
i am happy with what hieght the car has so maybe thats as far as i can go. has anyone tried removing the sway bar to get more flex?

jacnden
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Re: Torsion bar ifs - How do I get more lift?

Unread post by jacnden » February 20th, 2014, 7:30 pm

hi guys
i see the mods have changed my heading. my fault, i didnt really make it clear :purplex: . i dont want more height but more flex and droop

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Re: Torsion bar ifs - How do I get more flex & droop?

Unread post by Peter Aawen » February 20th, 2014, 8:37 pm

Fixed! (the thread title that is!)

The sad news is that with torsion bar IFS suspension, probably the only way to get more flex and droop is to put longer arms on or extend the existing arms!! Not the torsion bars, the Upper and lower arms that support the wheel hub/bearing etc. By adding a couple of inches to the overall length (reach?!) of the arms, the overall length of the arc that the wheel travels thru will be longer without changing the torsion bar end at all - and that's effectively giving you more flex and droop from the static ride height!! But that's pretty much the only way you can do it without compromising the CV's etc.

Even things like diff drops etc don't really add any flex and droop, usually just change the static ride height the vehicle can be set at and and maybe correct the angles that the CV's & axles run at if you've wound up the torsion bars. Similarly, changing ball joint positions on the existing arms without extending the arms, changing or removing the sway bar, trimming the bump stops, etc all just allows the arms to travel closer to the extremities of the arc they already travel thru. The Calmini arms do the same, ie give you a higher static position and therefore more clearance for bigger wheels etc by allowing you to adjust the torsion bars a bit; but unless you change the suspension design itself or fit longer upper & lower arms, you won't be getting any more flex and droop. :(

Think of the Baja comp vehicles, many of them run IFS suspension with the arms pivoting right in the middle of the vehicle so that the arc of travel for the wheels right out on the end of those long arms gives you more travel than you'd get with shorter arms and the same suspension design. Oh, and adding length to just one arm (upper or lower) can help you correct the camber angles that winding the torsion bars up can mess around with, but to get a greater arc of travel for the wheel, you need them both longer! ;)
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Re: Torsion bar ifs - How do I get more flex & droop?

Unread post by mydmax » February 20th, 2014, 9:25 pm

jacnden
If you mean what some call a ball joint flip, is that what you mean? It isn't a flip at all or a ball joint reversal either, all it does is reposition the 4 bolt fixing of the ball joint body, below the top arm instead of above.
That does allow the top arm to get down to the stop only if the shocker can lower the bottom arm enough.
When that happens the CV is at a very high angle of drive and doesn't like it if at more droop than stock.
If you do that and then run much torque through the CV's the outers will often go bang. Jackaroo CV's pop the trunnions out of the CV bell out.

jacnden
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Re: Torsion bar ifs - How do I get more flex & droop?

Unread post by jacnden » February 21st, 2014, 7:47 am

thanks for all of that.
my upper control arm is close to bottoming out with the shocker on and does bottom out about 12mm further on when I take the shocker off. maybe that's as much as it has and then maybe I would be better off winding back the torsion bars a little?
I was thinking about calmini arms and ball joint reversal because I am at the limit of travel now and thought that might help, you all seem to be suggesting that it wouldnt

I am still interested if anyone could tell me what is the normal amount of droop on a stock torsion bar front and a wound up one
thanks guys

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Re: Torsion bar ifs - How do I get more flex & droop?

Unread post by Peter Aawen » February 21st, 2014, 9:25 am

Take the shock off & with the front of the car supported in the air on chassis stands, use a jack to cycle the front suspension thru its full range of travel. That's all the travel range you are going to get, period. Unless you want to start doing things like extending the arms or ripping the entire IFS kit out and replacing it lock, stock, & torsion bar of course! Diff drops, ball joint flips, Calmini kits etc don't change that range of travel at all, they just change where the vehicle rides within that range, some better than others, and regardless you still really want to keep your static ride height in the middle third of the range, even if it's pushing the high edge of it, cos any higher or less travel than 1/3rd will mean you loose droop (or compression if you are going the other way) and your ride will become dangerous (& illegal!) So yeah,it sounds like you are already pretty damn close to the limit of travel overall and droop available at that static ride height, and possibly not even in the middle 1/3 of the travel range at static ride height either, and if that's the case then you want to wind the torsion bars back until the droop is at least one third of the total travel range, or your vehicle isn't really safe to drive (or technically legal for that matter....) :(

Can't tell you what the 'normal' amount of droop is, because all manufacturers tend to set things slightly differently between designs and even between vehicles (to a lesser extent) as they come off the production line - there are lots of little variables like suspension ride height that they tweak to make the vehicle fit within their stated vehicle height spec; except that generally they all set the vehicle's static ride height pretty much in the middle of the total range of travel. And practically (& legally) you can't adjust it too far away from that, which is where the 'keep in the middle third' comes from. It still leaves enough down (and up) travel for the suspension to act as a suspension under those circumstances the vehicle was designed to operate in and handle safely under the catered for driving demands & loads etc.

Still, all that means in general is that you won't ever get much more than 40mm of safe/legal lift out of an IFS suspension simply by adjusting the torsion bars/springs; if you want more lift than that, you hafta do things like diff drops etc to keep the driveshaft & CV angles workable & the ride within those safe/legal parameters but you still won't get any more total travel than what you get once the shock is disconnected as above.

The only way you can increase that total travel on an IFS suspension is to start playing with the mounting/pivot points &/or the arm lengths - and as soon as you start doing that, the design, engineering, & handling implications start getting reasonably complex, but if you find someone interested enough who either knows the calculations required to get it all right, or can find out what/where they are and do them correctly, and you then manage to transfer the design/calculations into reality under the vehicle, it can be done & has been done & even engineered for road use too!! But it does tend to get a fair bit more expensive than just winding the torsion bars up or even fitting a full Calmini kit! Sorry. ;)
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jacnden
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Re: Torsion bar ifs - How do I get more flex & droop?

Unread post by jacnden » February 21st, 2014, 10:04 am

thanks peter , you summed it up perfectly

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Re: Torsion bar ifs - How do I get more flex & droop?

Unread post by MasterInnovator » February 21st, 2014, 6:54 pm

Don't mean to hijack-
Peter, you mught be able to help me...with my vehicle-torsion IFS of course, I want to do a 3" lift to get more travel...that would mean that I would have no droop because of the droop stops. If I lowered the droop stops I would in theory get more down travel, but not only that, it would set the ride height back to the middle of the full travel range-Firstly, am I thinking about this the right way, Secondly, Would this be able to be done with it still being legal cos it would reset the static ride height to the middle of the travel range and still allows droop...legality being my main concern here(Modification to the droopstops that is, not the lift as that can be reversed easily!!!)! Again, am I thinking about this the right way in terms of the legalities involved...
Although I will also ask the engineers about this matter when I get my conversion mod plated...but just want some info first

I might add that I have already been forced to drop my diff 37mm as part of my 2wd-4wd conversion, and when its bottomed out on the bumpstops the cv angles still seem to be with in acceptable range

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Re: Torsion bar ifs - How do I get more flex & droop?

Unread post by Peter Aawen » February 21st, 2014, 8:00 pm

You aren't allowed to cut or move the bump/droop stops on an IFS torsion bar suspension MI, and even if you were allowed, you'd most likely be cycling the CV's & driveshafts out of their safe operating range & probably break or separate them too.

So I don't think it's doable legally or practically, but ask the engineers about it - and I don't mean just a mechanic who can sign off on a roadworthy inspection, I mean a full on automotive engineer who can look at the design specs, the suspension & steering geometry, and extrapolate/calculate what the impact of the lift & any other changes you want to make would have on the safety of the vehicle and its driveability. Part of the reason those engineers are so costly is that their professional indemnity insurance has to cover any 'mistakes or miscalculations' that they might make that could mean accidents happening on the road once the modded vehicle hits the streets - but that insurance doesn't cover YOU at all, it covers them from the negligence charges and the wrongful death suits that may occur if they get something wrong!!

The reason that lifts/mods on these types of IFS vehicles are so stringently controlled/policed is that IFS suspension only operates properly/safely within a fairly limited travel range, the manufacturers have put in literally millions of dollars in designing, modelling, checking, and testing everything to make sure it works & has a reasonable margin of safety, and changing any of the angles/limits either uses up all those safety margins or pretty much exceeds them dangerously & completely changes how the vehicle will respond to varying road conditions and steering/braking input.... So it's the suspension & steering geometry that the engineer needs to look at, & how varying anything like the bump/droop stops or the arc the arms move thru, up to and including the arc of travel the wheel moves thru &/or how that changes the steering angles & how all that will impact on the vehicle's steering and handling.

So you need to find/talk to an automotive engineer, possibly an automotive design &/or suspension & steering engineer at that - even just welding on the brackets you already have made up will likely incur some variations, possibly even a significant variation in the handling & steering geometry unless the bracket is in exactly the same place it would be on the 4WD vehicles..... and without appropriate checking of the design & any changes you may have made, that might mean the first time you try to turn the steering wheel at any speed by as little as a few degrees, the road wheels may just pass the point of no return and suddenly slam right over onto the steering stops & jam fully at hard lock beyond even Superman's ability to straighten them, spearing you off the road & into the scenery....

Playing with steering and suspension design by moving mount points or changing bump/droop stops is not a really safe thing to do unless it's part of something like a Calmini kit (that's already been engineered) or unless you can get an engineer to check it all out first, and even then it should be tested off the public roads before taking it onto roads where you can hurt people besides yourself just to make sure that nothing like that scenario I've mentioned above ever occurs... :(
An Ex-Service person is someone who thought enough about their country & how great it is, how lucky we are to live here, to write a blank cheque made out to 'The People and Commonwealth of Australia' for the value of 'Up to & including my Life!'

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Re: Torsion bar ifs - How do I get more flex & droop?

Unread post by mydmax » February 21st, 2014, 8:04 pm

MI
If you lie down at the front of the vehicle you will see the relativity of the suspension components.
A 3" lift doesn't necessarily give you more usable travel and only some of the 3" can be poached as an acceptable amount.
The more the lower arms are held downwards for normal travel the more the suspension will become harder riding.
How have you engineered the longer shocks to give the same upper limit and have 3" additional down. The Physical possibilities of that have been considered by Isuzu and they didn't do it.

The top ball joint isn't in the centre of it's movement. Making the suspension able to go further down makes the top arm drop inwards at an ever increasing rate. The ball joint has a finite amount it can move through before the neck of the ball binds with the joint body. ie, there is only so much angle change available. Repositioning the ball joint flange below the arm will sort of make that angle not so great.

The bottom ball joint also has it's limit.
If there is much change from OE the forces of the weight on the balljoints is not being taken through the central area of the joint design but all force is therefore to one side. Ball joints aren't a complete cup. Find one and cut it in a section view will increase the human respect factor considerably.

The only way to work out some of these things is to carefully measure all relative parts with respect to a base line and measure bump clearances and then decide, "if I want this far what moves where".

With CV's many people say the angles look OK and seem acceptable, but most don't remove the CV boot to see where the trunnions are actually running and how close they are to popping out and creating forces at the very edge of the CV bell where it is weakest. It is on lock and full drop the real test is. Who bothers the check both at once, Ok I suppose if you don't intend to turn the steering while driving.

Jackaroo outer Cv's pop out when the shock moves a bit. ie Full down and on lock. CV = no good anymore. Very similar suspension.

PS I'm puzzled as to how you know you had to drop the diff 37mm as part of the conversion when you didn't have a diff there to begin with.

I drew up a fair bit of the front end design a while ago and it does have it's limits.

Cheers
mydmax

jacnden
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Re: Torsion bar ifs - How do I get more flex & droop?

Unread post by jacnden » February 21st, 2014, 8:46 pm

even with my limited knowledge of suspension i cant see how you can get a 3 inch lift and have any usable suspension travel. as i understand it every mm you raise the torsion bars you loose downward travel.
37 mm diff drop? what car is it and how did you achieve that much of a drop

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Re: Torsion bar ifs - How do I get more flex & droop?

Unread post by MasterInnovator » February 21st, 2014, 9:06 pm

My Dmax
Have you seen my thread, mydmax on the conversion?, if not have a look in there and you will see how I did my mounts which dropped the diff 37mm...On this vehicle there is a nut inside of the frame rail with a hole through the frame rail to put the bolt through to bolt on the diff, but being two wheel drive that nut was not there and all there was, was a blind hole where the bolt would usually go through. My mounts lowered the diff as a result of making clearence to get to the nut/to even have a nut at all.
Damn thats what I didn't think about-ball joints
The thing that has me wondering though, is I hear alot of people have gotten 3" but can never seem to find out how /what they did

jacnden
look in the Build thread section and look for 2wd-4wd conversion, 2nd page you will see what I did for the diff drop-car is 2011 holden colorado mate.

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Re: Torsion bar ifs - How do I get more flex & droop?

Unread post by MasterInnovator » February 21st, 2014, 9:09 pm

What about wedges, where the ball joints attach on to the arms, like how a correction wedge works to correct uni angles...put some wedges in and that would correct any odd angles in the balljoints...provided the amount that needs correct doesn't require a huge wedge

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