Front Suspension Mods or Just Nonscense (Race Application)

[Dale M.]

Ok here goes..... I have struggled through most of the "chassis & suspension" setups of this thread and think I have concepts of whats going on.... BUT...

http://www.shoptalkforums.com/viewtopic ... 1&t=136863

I'm dealing with ability to adapt how front beam and car responds more to weight balance..

Let me set this up.. Its a fiberglass buggy (69 chassis ) so its a BJ and IRS.... Pan itself sit pretty much level in state its in right now (race ready - or maybe that is a misnomer) ... Extremely low and ball joints almost at end of practical travel (motion) at rest....

Weights per wheel are as follows as way car is setup ring now...

Left Front - 216 lbs.
Right Front - 214 lbs.
Left Rear - 415 lbs.
Right Rear - 420 lbs.

OK..ok... I could not have gotten it better if I really tried, but this was how car was build with eyeball and ruler setup on a somewhat frame jig.... Problem is this is without driver in car, when I get in I'm adding about 220lbs on driver (left) side of car...

Where I'm going with this is there is several ways to weight jack at rear of car ( Sway A Way center section for rear torsion bar mounts or adjustable spring plates) and by doing this I can can change front wheel loading to some extend to balance car.... Except there is a equal and oppsite reaction that each time I change one rear setting to apply more (weight) pressure on opposite front wheel it tends to lighten other side... I watched a fellow racer with FG buggy and on a $1300 set of scales go around his car about 4-5 timer adjusting spring plates to get balance every time he changed one setting opposite setting shifted and he could never get car into equilibrium..

What I have come up with and am wondering if I'm on right track here...

IN stead of severely dropping front suspension with stock spindles and center mount beam adjusters, is to take a different route and use dropped spindles so ball joints are working more with in there "useful" range and and still be able to maintain some symmetry with the geometry and trying to get roll center lower..

The real issue come down to balance... How to I get car when "loaded" with driver to get a better balance... I think the answer may be weight jacking and mentioned on rear of car but how to on front.... Well ... Here is concept.... Using typical BJ beam is to add lowering adjuster in center of upper beam... Nothing unusual there .... BUT here is the trick.... Put two adjusters in lower tube one each side of center but as close to center as design allows.... Then cut lower torsions in half and drill new "divots" in ends of "split" torsions allowing each side to have a certain amount of adjustable... This brings into picture the ability to have weight jacking abilities on all four corner so one may be able to "adjust" balance according to what ever means to get proper 4 point balance of car (ready to roll with driver)...

FrontBeamMods.JPG

The two horizontal center lines are sort of self explanatory... The actual mod is the addition of the three adjusters (green blocks)... and front "half torsion bars" Taking this concept a tad further, one could go "formula vee" concepts and use split torsions on lower beam, do away with upper adjuster and torsion bar and place rod across to tie both front arms together and act and a anti-sway bar ( or not) ....

Since FJC seem to be the most experienced here on competition suspension, I really value his advice.... Please tell me I'm not "out of it"....

I realize I can not just shove the weight half way across car with this method. but it may better allow me to place the weigh more evenly on front wheels so In can have a equal reaction whether I'm turning left or right on race course...

Dale

[Ol'fogasaurus]

Dale, would another option be to go with the dropped spindles but instead of playing with torsion bars, put through rods in and then go to adjustable coil over shocks?

Lee

[Dale M.]

Dale, would another option be to go with the dropped spindles but instead of playing with torsion bars, put through rods in and then go to adjustable coil over shocks?

Lee

That is valid alternative, but neither front shock towers or studs on trailing arm are really designed for suspension loads... And to beef them up takes a fair amount of work and adds more weight, then the are the body mods to clear the "beef" ....

Dale

[Marc]

The front roll center of a trailing-arm suspension is at ground level, regardless of whether "drop" spindles are used or not...but by all means switch to drop spindles if you're out of BJ travel at desired ride height. It's either that, or raise the attachment points of the entire beam.
No amount of fiddling/fussing with weight jacks can move mass - the total sideweights will remain essentially the same. To achieve total "balance" you'd have to bolt 220 pounds in on the right side, at a height even with the center of the driver's body mass. I think we should agree that whatever ill effects caused by the "imbalanced" mass placement would be more than offset by not having to haul around 220 pounds of dead weight.
Using dual torsion bar adjusters on one or both front tubes is a simple way to add more wedge adjustability, but you'll need to shorten the spring stacks and redrill them. I wouldn't recommend supporting the entire front weight by the stock shock absorber mounts alone, but you can get away with a hybrid arrangement using light coillovers which carry ~1/3 of the weight and afford easy adjustment.
Y'know what a simple, pragmatic approach would be that'd probably end up being 90% as good, for a whole heckuva lot less work? Simply cut the small leaves in some or all of the front torsion stacks off, just to the right of center. You'll need to tape the bundles together to get them installed, but once the grub screws are tight they shouldn't go anywhere.

[FJCamper]

Hi Dale,

Only formula cars with drivers seated center-line are going to reach any real balance.

Those of us with street configuration cars, driver on one side or the other of the shift lever, have very few options. You have good overall balance. All you need is ballast to offset your own weight. And ballast brings its own problems.

I don't recall if you ran comparative runs with and without a passenger to check your times. Ballast can of course go right into the passenger footwell, but you can use less ballast if you can mount it in the right front framehead area. Ideal ballast is metal plates bolted down.

As you are now, unbalanced, you are going to be faster in left turns than right turns.

FJC

[Ol'fogasaurus]

Dale, would another option be to go with the dropped spindles but instead of playing with torsion bars, put through rods in and then go to adjustable coil over shocks?

Lee

That is valid alternative, but neither front shock towers or studs on trailing arm are really designed for suspension loads... And to beef them up takes a fair amount of work and adds more weight, then the are the body mods to clear the "beef" ....


Dale

After reading what Marc and FJ wrote and looking at your drawing again; I wonder if getting another ball-joint beam to work on without putting either one of your buggies in the racing hospital and stiffen up the shock towers (that should be done anyway not matter which way you go) and build yourself a beam leaving the old beam for an option if it turns out the split torsion bars don't work as well as you want (it is possible that you could also nick a leaf or two so it breaks one of two of the leaves on the right side when you put a load on the beam to handle the load imbalance).

Adding the three adjusters is going to be a lot of work anyway but the stiffening up of the tows would leave the option of going to coil-overs later would still be there. It is either that or spend the $3¬ plus K and get an IFS setup.

Lee

[ONEBADBUG]

Dale, I have considerable experience autocrossing my buggy, and making it faster. My question to you is whether you are trying to reduce your times, or just want to experiment on your car. It's all good either way, I get the experimenting thing. I think your proposal is not the way to go faster. The most important thing in Auto-x is the driver, the next is the tires, and the last is the car.
I wonder why your car is so heavy, you reported 1265 w/o driver, mine only weighed 1080 with a serious cage.
I noticed in your picture you had a front sway bar. Unless you have an even bigger rear bar, that should go away.
You should try 1/8 or 1/4 inch toe OUT, it will help turn in a lot.
You should put a whole bunch of negative camber in there too, get some of those offset adjusters. I'm talking like 5 degrees, it won't drive for poop on the street, but your car is a dedicated A/X er right?
Unless you have brand new tires, pour some gas on them 10 minutes before you run. I'm serious, it is worth like a full second.
Steve

[Dale M.]

ok..... I guess another lame idea bites the dust....

Reply to some comments.....

Yes I'm all for making car go faster and handle better, trying to compensate for poor driving skills...
As for car weight, I can trim it down some, by removing 33 lb chunk of steel under front beam, smaller battery, dumping passenger seat (its poly so not much savings- but then no passenger for ballast).. There is not anything extra on car that is not needed (except fire extinguisher)...

Yes I realize dropped spindles will allow more front end motion, but am not sure if the is a "problem"....

On front I am running as much negative camber I can crank into it using aftermarket camber adjusters (trying to maintain as much front tire patch as possible)... Yes car has the mandatory caster shims...Toe out is about 1/8 inch for front and 0 to 1/16 inch toe in on rear.... I have removed all the "half" leaves in front torsions keeping all the main leaves and have adjusters on both beams.....

Buggy only has 3 gallon fuel tank I guess I could carry one about 1 gallon in it for "runs"...

Running 3/4 inch anti-sway bars front and rear..... Maybe I should forget them... That would shed some extra weight also....

Guess I could replace all the 5/16 bolts that holds body to chassis for 1/4 inch and save some weight....

Added Kafer Cup Bar/Truss Bar this off season, but didn't notice first outing this year (New Years Day) any thing significant ....

Have really though about new chassis putting driver in center of car ( and maybe a few inches further forward) and mid engine it, but have not worked out rear suspension concepts yet...

Please understand guys I am always about 5 seconds behind the class leader, we (about 7 buggies in class) are all running about same weight in cars, all running about same suspension (but 5 are K&L/swing axle and mine and one other are BJ/IRS and he is faster than me and I built the car...) , almost identical motors, and pretty much same tires..... Got to believe the poor times are because of the driver, although I am trying to get the very best out of the car... But I don't think I'm going to find the 5 seconds mechanically....

Anyone want to buy a "race car(?)"....

Does all this sound like a whine, sure it is.... I am so frustrated with all this its about to end my career as a auto-x driver.... I don't know what to do... Do I a drop another 5k into car for bigger motor/better tires whatever, take driving lessons (have has two "auto x track sessions" already) and have been flogging the cars since about 2004, (ran my street buggy about two years before building a dedicated car) or get a different car (front engine) that does not have all the inhere handling problems that come with a car with a excessive light front end.... Or just find new hobby....

Dale

[Ol'fogasaurus]

Frustrated; yes, whining; no. Your too young to sell out and quit or move into another hobby and start all over.

When I was in a Rally/Autocross/Ford Motorsports car club maybe 30 or 40 years ago the auto-X'ers were talking about how their suspension was or wasn’t working; e.g., reacting to the track faster. Guys I knew who were road racing used the same term and I got the impression that they both were talking about how a car came out of a corner (or into a corner) and reacted/transitioned into going to or from straight ahead. That lag in transitioning seemed to be costing them time/position no matter how good/smooth they (thought) they were at driving. Could that be what is going on? Balance was part of it but the suspension itself was also a big part of it too.

Lee

[ONEBADBUG]

"Guess I could replace all the 5/16 bolts that holds body to chassis for 1/4 inch and save some weight.... "

That ought to do it!
I wish I could walk the course with you. It's impossible to explain everything on a forum. I could post up some of the driver school stuff I developed I guess. Back on topic. Have you
measured tire temps after a run? Are you able to feel what needs improving on the car? It's not easy, because you get so focused on your run. Does it understeer with that front bar?
Are you in an actual SCCA class, or can you make any change you want?

[Ol'fogasaurus]

Dale, I forgot to mention that I also think you are correct about the shock studs are a little on the wimpy side but a lot of people use them as they are good or bad (until they break one then have to find someone who is willing to do the fix... assuming they can find the studs themselves. If you are going to get that serious about this I suspect that a pair of beefed up or custom arms, with bigger and better placed studs could be had as long as the rules do not preclude this fix.

Lee

[Dale M.]

"Guess I could replace all the 5/16 bolts that holds body to chassis for 1/4 inch and save some weight.... "

That ought to do it! :D
I wish I could walk the course with you. It's impossible to explain everything on a forum. I could post up some of the driver school stuff I developed I guess. Back on topic. Have you
measured tire temps after a run? Are you able to feel what needs improving on the car? It's not easy, because you get so focused on your run. Does it under steer with that front bar?
Are you in an actual SCCA class, or can you make any change you want?

Yes I watch tire temps (across tread width) and adjust pressures accordingly between runs.....

As for car class and mods we are independent group but pretty much follow SCCA rules on "class" and "mods"... Since I'm running in D Modified (fudging a bit on "cc's" ) but everyone in "class" is so nobody cares, I can do pretty much what I want to car and long as its "safe"...

Yes car under steers unless I get it "setup" to apex turn properly.... I understand walking course and setting up car in proper line to make the corners and have car in correct place coming out of turn for run at next turn ( its usually me tagging along behind novice group at walk thorough - listening to the "pro" instruct newbies how to drive)....... The car will not always let me do that though.... Some people tell me I'm not aggressive enough, some tell me I am to late in trying to apex turn, some tell me I am to early in starting to make turn......

Then there was a situation at first event this year... I kept getting staged in line behind another driver that was in the car/out of the car/running off to crapper/ taking off to talk to friends/ late in checking tires/ and by time that person was "ready" there was 7-8 car gap between her and start line and then it was a rush to get to start line.... That threw off my concentration a bit....

I am having thoughs of pulling both sway bars off car, pull out passenger seat, drop off weight under front axle and move battery forward in passenger side foot well and start over....

It still comes down to at what point do I quit blaming car (not really) and it becomes crystal clear I'm not a driver and should really be contend in maintaining my 5 or 6 place status in ranks.....

They my idiot buddy (the shoe) comes along and says "but we are having fun", one of these days he may be wearing a "wide five" for a belt with his arms pinned to his sides.....

Dale

[volksbugly]

Since this is an all out autoXer I would say make it mid engine, just flip it around. Lots of labor, yeah... cost to you, mostly your time. Of course this would totally change everything you already know about the handling of the car and you would need a reverse R&P (I think??) anyone please chime in on that cause its a guess.

nice drawing towards the bottom of a mid engine setup
http://www.loumash.com/GS/aboutthegs.html

[Chris V]

So, what happens when someone else drives your car? Does it go faster?

[Fiatdude]

The magic secret you want is one word -- LEAD -- You are already driving a light car and your body weight is what percentage of the total weight of the car????? Its 17% -- your not going to find that much of a solution in your suspension -- -- So you have to add weight (or move weight) to balance your car, unless you always want to go left. Now the good news. You don't have to add 220#, If you put the weight as far out as possible (on a glasser you could actually attach outside the pan) you'll be able to get away with about -- oh let me guess, -- about 150- 165# and when you look at it that really isn't that much. Or you get some aftermarket pedals and move the steering and put your self in the center of the car -- like a go cart. -- but you've got stuff you can move, Like the Battery, go to a fuel cell and place it to the left as far as possible. put everything that is attached on the left side of the car and remove everything that is attached on the right. a buddy of mine built a little area outside the body on the left side, still under the overhang of the fiberglass, and put the battery, fuel cell, ingition modual, etc etc in there..... think outside the 'box' LOL

Dropped spindles are a must -- get that suspension working dude!!!!