Advanced Suspension Mods

[russian]

Any ideas on stiffening the rear side? Like do we want a sway bar in the back? Or do we want steel angles welded to the torsion beam?

[jemartin144]

On my racecar the previous owner used a civic roll bar in the rear to improve handling. He made brackets for it to mount in the rear near the bumper and then it bolts up to the beam. He did it that way so that he could choose to run with or without the stiffer rear. In the dry he usually ran with it, in the wet without it. This is with all stock suspension, except coilovers, btw.

[Advancedynamix]

Rather than running a sway bar I chose to reduce the amount of static sag (or droop depending on the school of suspension theory you subscribe to). When you reduce the amount of suspension sag to only what is necessary (especially on a trailing beam suspension) you limit the amount of body roll. Sway bars are necessary when you need a lot of suspension travel and you need to control that travel in corners i.e. street cars that travel rough roads, off road vehicles, and heavy cars. The most efficient way to control body roll on the festive is to reduce static suspension sag, but for those of us that don't have perfectly flat roads (my roots are in the western foothills of Maine, where nasty tarmac is almost smoother than the dirt washboards) a good setup would be to use a bar that follows the profile of the rear beam that has adjustable end links, similar to a bar for a mk1 VW.

[TominMO]

Any ideas on stiffening the rear side? Like do we want a sway bar in the back? Or do we want steel angles welded to the torsion beam?

There's the 5/8" threaded-bar mod. Stiffens up the rear beam noticably.

[russian]

Rather than running a sway bar I chose to reduce the amount of static sag (or droop depending on the school of suspension theory you subscribe to). When you reduce the amount of suspension sag to only what is necessary (especially on a trailing beam suspension) you limit the amount of body roll. Sway bars are necessary when you need a lot of suspension travel and you need to control that travel in corners i.e. street cars that travel rough roads, off road vehicles, and heavy cars. The most efficient way to control body roll on the festive is to reduce static suspension sag, but for those of us that don't have perfectly flat roads (my roots are in the western foothills of Maine, where nasty tarmac is almost smoother than the dirt washboards) a good setup would be to use a bar that follows the profile of the rear beam that has adjustable end links, similar to a bar for a mk1 VW.

pictures of the said bar?

here are the details on super pro bushings - http://www.fordfestiva.com/forums/sh...4&postcount=20

[jemartin144]

My race car only has about an inch of total suspension travel in the rear, so I would say it has very little travel. I'm not an expert when it comes to suspension setup, but I've always thought that for most front wheel drive cars you tune handling primarily though rear roll. Most front wheel drive cars understeer naturally. So, while more rear roll stiffness is desirable, there is a point where you could make it too stiff and start to get oversteer. The amount of roll stiffness you have in the rear is affected by the front also. So, if you're running a completely stock suspension in the front and go crazy with roll stiffness in the rear you are going to be sliding the rear end all of the place.

This is why a removable sway bar can be a good solution. After you get the stiffness to a good neutral place you can tune in how much roll stiffness you want depending on the track and conditions. ie, in the wet there is less grip, so you would run with less roll to maximize grip. Now less adjustability only really applies if you're running in different conditions and need to tune finitely. In most instances this isn't the case and you can just find a good balance for your setup and leave it that way.

[Advancedynamix]

An inch of travel on your festiva or the formula car?

[jemartin144]

The festiva racecar. There is almost 0 droop and maybe and inch of actual travel. I havent had a chance to get all the real numbers yet. I'm hoping to get the whole suspension modelled up sometime this summer and do some real analysis on it.

[Advancedynamix]

Rear roll control is a very important aspect of tuning an FWD chassis, but it's not the most important. The most important factor in the dynamics of any chassis is weight and its distribution. The trick is to keep as much weight over the driving wheels as possible. This is especially challenging and important in a front drive chassis since the driving wheels are also directing the car and handling roughly 80 percent of the braking. There is no right or wrong here, and a roll bar is an easy way to tune the anti roll, but it's not the only way. I prefer to fine tune the ride height, tire size and compound spring rates, shock travel/valving and alignment settings without using sway bars. Then, when everything is working together in balance I'll ad a sway bar as necessary.
with my festiva, I've found that a rear bar isn't necessary on an average road coarse. With my current setup the car will pivot controllably with moderately quick throttle lift yet it isn't a handful under trail braking. This is with the stickiest commonly available street legal tire that will fit inside a stock festiva wheel well. Wider tires or slicks could most likely make use of some rear bar. This is also with a heavier than stock engine/ trans that is moved 2" forward of axle centerline in comparison to a stock drivetrain. This is also a fairly stripped out car with no roll cage, so the weight of the cage and/ or interior could warrant the need for more bar. As far as this car goes though, more rear bar would slow me down. Things would be different on a really tight coarse or autocross, but I'd probably opt for higher rear ride height and stiffer/ taller bump stops. That changes my caster and puts more weight over the front wheels. The easily removable sway bar is a great idea though and I'd like to see pictures.

[Advancedynamix]

Here is an example of how much pressure is being applied to the inside front tire even without a rear sway bar. This corner was being taken at around 85mph, under power with 40psi hot in the front tires. You can see that there is enough weight on the inside front wheel to distort the sidewall of the r888. The bump stop on the left rear is doing it's job at keeping the weight where I need it.

[windy1]

genius

you re a creative genius. could u put a kit together,and sell it to the club? ill buy one

[alpaccino]

you re a creative genius. could u put a kit together,and sell it to the club? ill buy one

x2

[alpaccino]

Here is a little parts list for some of the components I used, where to find them and the cost.

KYB shocks for the Aspire/Festiva 116.00 for the pair. Ebay http://www.ebay.com/itm/2-Rear-KYB-G...ecb796&vxp=mtr

Small body shock sleeve kit-54.00 a piece, 2 required. Here http://www.ebay.com/itm/New-Bilstein...ab4dbc&vxp=mtr

1 7/8" 10" I.D. springs- 35.00 a piece (when shipping is split between 2 springs) here http://www.ebay.com/itm/NEW-MIDGET-R...bbb547&vxp=mtr

Raceland VW mk2/mk3 coilover kit- 400.00 est. go to raceland.com or here is a set on ebay. http://www.ebay.com/itm/1989-1992-vw...c6e16a&vxp=mtr

2 1/2" x 10" front springs- 35.00 a piece (with combined shipping of 2) on ebay. http://www.ebay.com/itm/NEW-RACING-C...304e4d&vxp=mtr

do you have the ebay link for the bushings?

[nitrofarm]

The bump stops don't actually stop the shock travel, they are simply there to raise the spring rate. They can be used to limit travel, but that's not what I use them for. The car will lean about an inch and then the stops progressively raise the spring rate on that corner. This isn't to induce overseer or to rotate the car at all. What this does is it allows the front inside tire to get traction when the throttle is rolled on using the outside rear bump stop (the extra spring rate works in conjunction with engine torque to keep from losing traction) To rotate the car I use the brakes and the front bumpstops do the exact opposite of the back, they take weight of the rear tires. Bump stops can be used to fine tune the spring rate of each corner. They can also be used to correct shock valving issues. On a front drive car I like to use fast compression dampening and slow rebound, this will stick the front end to the track when you brake before a turn and limit the amount if weight transfer to the rear under acceleration. The bump stops can be used to fine tune this.
Hope that helps.

So with a fast Damp slow Rebound in the valving.Does it roll more in a very high speed gradual curve?

[nitrofarm]

[QUOTE the raceland coilovers come apart fairly easily so they don't need to worry about overheating the strut insert when they weld in the bushings. You'll need a loose knuckle to have them match the pattern. [/QUOTE]
Am I the Dunce of the class?Or the only student paying attention? Where is this step? Did you seperate that steel clamp that surrounds the strut? All I see is the elongated upper hole.Or is that a HAT BUSHING in the lower hole? drool