springs & swaybars vs springs only (on gravel)

To complete the above thought (as a test of understanding and just as a way to dance a little jig because we're talking about what I asked about): the reason to add bars at higher speeds is to increase roll stiffness, and the reason that you don't just add more spring to get said added roll stiffness is because that gives up too much grip. Right?

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BillyElliot
Can't really shave them down without changing the structural integrity of the bar itself. .

Of course you can shave them. They're steel...What do you mean by "structural integrity"
They'll be thinner, and hence softer. I have an early Ford GroupA bar that was for gravel and it was milled flat..

Did you know that true progressive springs are made with taper ground wire?
They start with say 16mm wire and grind it to taper down to say 12mm, then wind it..
DMS supplied springs are taper ground, stock Xratty rears are, and many of the Ford motorsport FRONT springs are taper ground..

It's just steel.

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John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

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I guess my rears were not truely progressive wound. Mine have 4 or 5 coils close to gether and then the gap between the coils gets bigger. With a over all lentgh of 12"s once the close coils touch the spring rate climbs rather quickly. At least it does on my cheapy spring rate tool. Not sure what story an actual spring dyno will tell. I know switching to these springs in the rear dramaticly smoothed out the over all ride of the car. To the point of closer to cadilac then STI. Not sure if its faster on the stop watch.

I think the bars at higher speeds are to stop roll. Not add wheel weight. If it could be done threw geometry and not bars im sure theres even more speed. The way I see what Evan is saying is that at higher speeds the car transfers to much weight to the said rear tire to quickly and forces that wheel to have to much grip and over rotates the car to quickly. So i guess stiffer springs would actually take away grip and make the car feel more stable on entry but you would then lose over all grip in other aspects of the corner. Also forcing the shocks to do more work to control the wheel contact patch. Im no engineer so I could be way off.

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First rally 2013
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Once again risking the use of terms from road-racing....

Progressively WOUND springs are those with decreasing gaps between coils, while progressively GROUND springs are those with decreasing wire thickness. QA1s, for example, are progressively wound. The springs that DMS uses are a combination of progressing winding and progressive grinding.

(runs and hides)

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john vanlandingham
Did you know that true progressive springs are made with taper ground wire?
They start with say 16mm wire and grind it to taper down to say 12mm, then wind it..
DMS supplied springs are taper ground, stock Xratty rears are, and many of the Ford motorsport FRONT springs are taper ground..

It's just steel.

Taper ground or taper wounds, the result is the same as the increase in spring rate is still created by progressive coil-bind in both cases. Of course, a lot of cheap-o taper wound springs are just like having a linear spring duct taped to a linear helper/tender spring with the resultant 'step' function spring rate increase. But, a properly progressive wound spring should behave exactly like a progressive ground spring with a rising rate that at least somewhat smooths out the 'step' in the spring rate.

From left to right below
Left) Linear spring

Middle) Two linear springs -- progression is simply a 'step' from the lower rate to the higher rate when the upper portion of the spring binds. Note all 8 upper coils should bind simultaneously as each of the 8 upper coils is the same rate. This is the same as having a helper/tender spring and a main spring.

Right) Progressive spring -- as each of the upper coils collapses and binds, the spring rate ramps up in a smooth fashion.





Progressive tapered/ground (and perhaps wound) from DMS --- Allows three things
1) More efficient packaging than progressive wound only (shorter length for a given travel)
2) Less weight (contributing to both sprung and unsprung mass)
3) Perhaps more control of ramp-up rate

Of course, these do not look progressive ground or wound across the full length so there would be some 'plateaus' in the spring rate.



Edit to add another form of progressive spring that we rarely see on race cars. The large coils at the bottom are softer than the small coils at the top despite the coils being equally spaced and the same wire diameter so you get a smooth progressive rate as the bottom coils 'bind' or lay flat on the perch surface if the coils 'nest'.

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____________________________________________________________-

One. Class -- 2WD

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Edited 3 time(s). Last edit at 02/05/2013 02:49PM by Josh Wimpey.

If I can try to bring this back to my original question, I can see two reasons why several people seem to run bars with their springs when grip and/or speed is higher and simply delete the bars when grip and/or speed is lower:

1. this is a very easy way to switch back and forth between two set-ups, requiring only the attachment/detachment of the bars and adjustments to the shocks.

2. they actually want a pure-spring set-up for low grip and/or speed, and a springs plus bars set-up for more grip and/or higher speeds.

Which of these - or some third option - is the reason is exactly what I wanted to know. Any insight?

In my simplistic view of things. Whilst cornering you need the tyres to grip before you generate enough force to create body roll.

Plus if you are controlling and fine tuning body roll in corners using ARBs, I find it hard to believe that particular optimum ARB setting will just happen to also be exactly what is needed to work alongside the springs and dampers when the car is driving in a straightline and the individual wheels are dealing with ruts, bumps and humps in the road surface.

Have you got any vids of your car being used on these events so we can see what it is doing?

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Disappointingly not yet a Jackass

I'm sorry, but I have no videos. I also only have stop-watch data from a session in an open field at rallycross speeds. When my family ceases to have the flu, I'll see what I can do.

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Iowa999
When my family ceases to have the flu

Ewwww.... sorry to hear that. It is happening round these parts as well.

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Kirk Coughlin
Woodbury, MN and River Falls, WI

Quemadmodum gladius neminem occidit, occidentis telum est.

Thanks.

As to the issue of optimum bars, one of the neat little gizmos for Evos is an adjustable bracket for the front lower LCA. Combine this with an OTS multi-holed bar and you end up with lots of options, spaced almost evenly, from about 100 #/inch at the wheels to more than 200 #/inch. (You can also shift the entire range of values higher, by getting a heavier, multi-drilled bar.) Furthermore, if you've seen how the rear bars are attached to these cars, then you know that fabbing a similar, adjustable bracket for the rear would be easy.

But this only goes to show that fine-tuning with bars won't be difficult. And I'm still after the previous question: would a pure-spring set-up be better, even if only for lower levels of grip and/or speed.

[need coffee ... typos galore!]



Edited 3 time(s). Last edit at 02/06/2013 09:10AM by Iowa999.

A wise man once told me you'll never go as fast as someone who keeps their wheels on the ground. If the purpose of asb's is to keep two wheels and the chassis incredibly firm and you are driving on lots of broken/uneven surfaces (including lots of ditch hooking and elevation changes) I'd ditch or lessen the bars. I always think of the first image I saw where a car had one of its two rear wheels on the ground, the other one off due to the rigidity of the asb and suspension set up. If you're making a number of dips and turns on a forest road (Nemadji Trail or Ojibwe Forest come to mind) then I can't imagine you will go much faster than the rest of the field if you aren't driving all your wheels. Fancy techno liquid center diffs that auto balance for you aside of course.

If you are going to spend the majority of your time driving through cones in farm fields I imagine tightening everything up shouldn't be too bad.

Mind you, I've only ever course marshaled before and gave up on my old rally car to go back to school after many years... so you'll probably want to keep asking... but I'd wager you'll need multiple generic setups if you are challenging locally or nationally for stage rally... and only two or three setups for rally cross.

Full disclosure: If I win the lottery anytime soon (which is hard to do if you don't but tickets) I'm going to stage rally a Rolls Royce... (Woo hoo!)

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Kirk Coughlin
Woodbury, MN and River Falls, WI

Quemadmodum gladius neminem occidit, occidentis telum est.

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Tom B
I would love to fuck up your world in a 2wd car on stage, its one of my favorite things to do to the 4wd contingent....and in comparison to Antoine I SUCK at driving.

NOTHING MATTERS.

BS Tom. What MATTERS is a desire to win and being willing to leave the right foot on the mat.

Not many will. How many of us would take their EVO MR out there and see just how fast it can go? I would but an mot interested in playing the soda-straw game.

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JohnLane

Overkill is consistently more fun

Bring it up Jay. Field is a little soft and stinky but it will rinse off.

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JohnLane

Overkill is consistently more fun

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Iowa999

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BillyElliot
You must have missed the part where my front bars are hollow.

It's actually worse than that. I read your post carefully and didn't connect the dots that it would be difficult to impossible to shave a hollow bar. I also let my annoyance at the guy who doesn't get sarcasm (in others) make it sound like I didn't appreciate what Jeff wrote. I apologize to both of you.

edit: he's an autocrosser, but I don't think there are many people in the world who know more about the various suspension parts that are available for Hondas than Andy Hollis. He can be reached through SCCAForums or FlakeBook: https://www.facebook.com/HollisRacing

I can give him a shot, thanks but I'm not sure how much I'll get since most Autocross setups go for super stiff springs, short travel dampers and big bars.

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Reamer
Why does Billy want a smaller front bar and what other choices in set up does he have because his bar selection is limited?

Because running no front bar I still have this floaty feeling in the front. Ideally I want to bump down my front spring rate a bit and run a softer than stock bar on gravel if I can.

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john vanlandingham

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BillyElliot
Can't really shave them down without changing the structural integrity of the bar itself. .

Of course you can shave them. They're steel...What do you mean by "structural integrity"
They'll be thinner, and hence softer. I have an early Ford GroupA bar that was for gravel and it was milled flat..

I'm not saying they can't. You can take off a mm off and might not hurt it, but I don't know at what point you shave it and then put twist into it and the bar won't spring back because you go into plastic deformation. Also the front bar isn't really something that seems easy to shave.





Edited 1 time(s). Last edit at 02/06/2013 10:53AM by BillyElliot.

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Reamer
I talked to Evan Cline last night about bars and what he ran. He is not Lestage but he is quick with what he has. He said you will really want sway bars going into a R5 at 90mph. He claims you dont want that much body roll at high speeds. That it slows the car down to much and ruins the entry to higher speed corners.

Ya know, one way that so many falsehoods get perpetuated in rallying is by guys that do well in a very shallow field talking too much. I see it locally from myself and friends and I see it Nationally all the time. I can think of three drivers right off hand that are faster than the entire current field and didn't run front sway bars in their PGT WRXs.
If you worry too much about optimizing the car, you probably think too much to be a fast driver.
Wasn't there a great Gronholm quote about thinking? Or was it McRae?

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Grant Hughes