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> sheridan 914 body kits
airsix
post Jul 22 2005, 09:26 PM
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Boy, I bet that thing is a handful to steer with that kind of geometry. Red line through strut should hit the ground well inside the contact patch. Just an observation - not meant to offend.

-Ben M.


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SirAndy
post Jul 22 2005, 09:37 PM
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QUOTE(airsix @ Jul 22 2005, 08:26 PM)
Boy, I bet that thing is a handful to steer with that kind of geometry. Red line through strut should hit the ground well inside the contact patch.

actually, it's surprisingly easy to steer that car ... not sure why ...

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Scott Carlberg
post Jul 23 2005, 01:04 AM
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QUOTE(kevgentile @ Jul 19 2005, 03:41 PM)
the photos are great and help out some, but does anyone have detailed photos of the "standard" body.
thanks for the help

Standard Body pics from Ultimate 914!
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Brett W
post Jul 23 2005, 01:32 AM
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It is pretty easy to steer because of the large amount of caster, but the large scrub radius probably beats the hell out of the driver over the length of the session.
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J P Stein
post Jul 23 2005, 09:28 AM
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QUOTE(airsix @ Jul 22 2005, 07:26 PM)
Boy, I bet that thing is a handful to steer with that kind of geometry. Red line through strut should hit the ground well inside the contact patch. Just an observation - not meant to offend.

-Ben M.

Once you're underway, it's not too bad...mine has a similar problem. At low speed in a tight situation(like in the pits) it sux. The tires shuffle.....think understeer at 5 mph. Fortunately, parallel parking is not required (IMG:style_emoticons/default/biggrin.gif)
The wonders of Macpherson strut suspension. (IMG:style_emoticons/default/confused24.gif)
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airsix
post Jul 23 2005, 02:53 PM
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QUOTE (J P Stein @ Jul 23 2005, 07:28 AM)
Once you're underway, it's not too bad...mine has a similar problem. At low speed in a tight situation(like in the pits) it sux. The tires shuffle.....think understeer at 5 mph. Fortunately, parallel parking is not required (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)
The wonders of Macpherson strut suspension. (IMG:http://www.914world.com/bbs2/html/emoticons/confused24.gif)

I wasn't thinking too much about steering effort - more about feedback from dips, bumps, pavement joints, etc. The farther outboard that tire is the more leverage it's got to yank the wheel around in your hands. (I'm having momentary recolection of the time I was fording a stream in a deux-n-a-half and hit a rock that spun the wheel so fast one of the spokes broke my thumb.)

-Ben M.
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bd1308
post Jul 23 2005, 05:36 PM
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i got a finger stuck in one of the decorative hole in the spoke of a grant steering wheel in my Jeep.....


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Brett W
post Jul 23 2005, 09:09 PM
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Ben is right. Large scrub radius can make a race car very hard on the driver. The feedback through the wheel will tire out a good driver.
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airsix
post Jul 24 2005, 09:42 AM
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QUOTE (bd1308 @ Jul 23 2005, 03:36 PM)
i got a finger stuck in one of the decorative hole in the spoke of a grant steering wheel in my Jeep.....


LONG day

(IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif) NICE. Makes me feel I'm not so alone in this world. I thought I was the only one who gets into messes like that!

-Ben M.
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Brad Roberts
post Jul 26 2005, 01:42 PM
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Correct. The bumpsteer is dead on (adjusted at the strut) The key is "track" It takes little to NO effort to make the car turn in. Feedback is no worse than anything else I have driven with 10inch wide radials and NO rubber in the steering system. Feels just like a go-kart.



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redshift
post Jul 26 2005, 01:48 PM
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QUOTE (airsix @ Jul 24 2005, 11:42 AM)
QUOTE (bd1308 @ Jul 23 2005, 03:36 PM)
i got a finger stuck in one of the decorative hole in the spoke of a grant steering wheel in my Jeep.....


LONG day

(IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif) NICE. Makes me feel I'm not so alone in this world. I thought I was the only one who gets into messes like that!

-Ben M.

(IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif) You wish.

I used to have this girlfriend who wore cross-your-heart Chinese handcuffs.

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andys
post Jul 26 2005, 04:16 PM
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QUOTE (Brett W @ Jul 22 2005, 11:32 PM)
It is pretty easy to steer because of the large amount of caster, but the large scrub radius probably beats the hell out of the driver over the length of the session.

Brett,

Large amounts of caster would make the car yet more difficult to turn and produce a lot of weight jacking. Caster is good for keeping the car stable in a straight line. Pehaps you meant *small* amount of caster?

The picture suggests there's a lot of scrub radius, which in itself is not necessarily a bad thing, but it accentuates steering effort/feedback and weight jacking when caster is increased. Can't tell from the pic, but it's possible that the KPI was reduced....which will reduce steering effort (generally). AFAIK. Thoughts?

Andy
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Brad Roberts
post Jul 26 2005, 04:38 PM
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Caster is not adjustable on this car. It was set at -6deg. We played around for years from -5 to -6. When the chassis was on the jig the camber plates were welded at -6.

About the only time where I have seen caster make a difference is in AutoX. otherwise I personally set them all up between -5.5 to -6.0

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Brett W
post Jul 26 2005, 05:59 PM
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Lots of "negative" caster will not make a car hard to steer. I ran 6 degrees on my street car and have designed as much as 10 degrees into some race cars. It is good for camber gain in a strut situation. This "jacking" effect that you refers to really only occurs at large steering angles such as those incurred in a street car. Race cars don't use anywhere near as much steering angle. The KPI can be used to offset this in a street car. Since the factory set the strut at a 10 degree angle running, the drawbacks of large amounts of caster are offset by the KPI.

A large scrub radius is bad thing anyway you look at it. Any bump of cornering force exerts a twisting force on the steering that is proportional to the scrub radius. Cars with zero scrub radius can be driven without power steering becasue these twisting froces are gone. But zero scrub radius cars can feel very numb. The driver needs a little feedback to "feel" what the tires are doing so havinga minuimal amount of scrub radius is useful. In my cars I shoot for a minimal amount of scrub radius. In most applications the large amount of KPI that the factory built into our cars helps decrease the large scub radius because the wheels can't be crammed over the struts.
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pokey1168
post Jul 26 2005, 06:45 PM
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OK, just so you guys know. I have been under and around cars my whole life. I deal with some technically advanced medical implants and procedures, but listening to you guys talk about the suspensions on these cars makes me feel like a monkey doing a math problem.

BTW I am dam# glad to know that there are people like this that I may have to call on later for the rust bucket.
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J P Stein
post Jul 26 2005, 08:08 PM
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The feel is a good thing......if the car even starts to push, you feel it immediatly through the steering wheel. As for turn in....with front & rear toe out it turns in super but as the lock increases so does the effort....I notice myself grunting when I really crank some in......the good news is it will snap back *real* quick if you let the wheel slip back thru your hands to catch one of them tank slappers.
These are mostly autocross problems/set-ups. I'd hate to drive my car at high speed on a track with it's present set-up
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Brad Roberts
post Jul 26 2005, 08:13 PM
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The knowledge available is unmatched here. Some of it is difficult to digest, 99% of it has to be experienced to understand. Unless you have raced or "worried" about scrub radius... none of it means much. The car pictured requires about 4 inches of "turning the wheel" to make it go were you want. It is not ideal, but SCCA allows for something like 52 inches of front track for GT2. The wider the track the easier the car turns in. The front track on this car is .500 wider than the rear. It is almost impossible to get this car to understeer (even in tight stuff).


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Brett W
post Jul 26 2005, 11:49 PM
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Now you guys can see why I have such a fit when someone says "just crank the t-bars down to get the car lower" , "it'll handle better".

Brad is correct, when you widen the front track width you decrease the weight transfer, thus allowing to for better cornering as well as less diagonal wieght transfer. Most street cars come with either equal or smaller front track. My race car will have a track of 60 inches front and 58 rear. It should work great.

The only drawback to wider track is the increase in frontal area which can cause more aero drag. Many F1 cars have track widths of 54-58in where many dirt track cars have a track width of 80-88in. Rules really determine where that falls.
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pokey1168
post Jul 27 2005, 04:09 PM
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OK, after reading and trying to keep up, don't be too surprised when you see me on here begging for advice. I have the floorpans to worry about first, but rest assured the work will definitely get around to suspension set up. She won't be going back to original, so I may let her get closer to the road by a couple of inches if I can do it without losing to much in ride quality. (IMG:http://www.914world.com/bbs2/html/emoticons/welder.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/sawzall-smiley.gif)
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J P Stein
post Jul 27 2005, 05:10 PM
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An observation from the driver training thingy.

On a 75 foot radius skid pad every car there understeered...initialy at least......this included all the Porsches, a Beemer, even a Honda NXS or what ever the rear engined jobbie is called. With some coaxing, a few got the back end out. The new 997 (8?) "S" that wouldn't turn off his stability controll & plowed around all day....but not as bad as the Hemi Charger (?) 4WD station wagon that slew it's front tires.

Did I mention that R35 Hoosiers have a fair amount of grip?
I was cooking till I hit "the bump" & bounced my haid off the cage...even with bar padding & the helmet it knocked me crosseyed....that was enuff for me.
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