Landracing Forum
Tech Information => Steering - Suspension - Rear End => Topic started by: Harold Bettes on May 12, 2007, 01:22:29 AM
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Hey Guys,
For a Gas Coupe / Sedan: Is a total suspension travel of 2"-3" enough for jounce/rebound? :? I know that the salt is far from a billiard table, but I also don't want too much travel. :-o I want to limit the travel and still have enough to allow the tires to follow the available surface to generate acceptable traction. :wink:
Also any comment on shock rates that have proved to work well for the full body door slammer critters? :|
Thanks and Regards, :-)
HB2
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Harold, in my opinion the less you have the better. I run my 4500# car with the front suspension near bottom out, using 550# springs on the front and 400# springs on the rear. I would also recomend heavy sway bars fore and aft. Keep the car low as possible, same with ballast. Use a front air dam if legal for the class. What you don't want is spring rebound which allows air to suddenly get under the car unless you like to back thru the lights.......................
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The drive train needs a minimum travel to be flexible but you can never design it to be compliant because the surface changes so much in the span of a run and from one run to another.
The required geometry changes were all done with modifications to stock parts.
I limited my cars to about 1 inch total.
Modern cars have a lot of work done by the OEM for aero stuff and will have a device under the front bumper already.
I sorta preferred to lower the car to almost scrape the ground and with a slight tail up angle to let more air out than in.
Added front air dams have a use ,but for my application they made the front of the car larger. :wink:
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If you use a wheel rate(not to be confused with a spring rate) equal to the corner weight you will usually end up with 3/8 to 1/4 inch travel which is more than enough..
Jack I am with you low is good and small as well. I might add if it has broad flat surfaces on the topside you might want to add 'landing gear' as well. It is a 3 dimensional world at least and you can spin in all planes.. pun intended.. If you get everything else right adding lightness can help a bunch as well. Think of the 1/4 speed as your 60 ft time and you are on the right track or portion thereof..
Dave
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"Think of the 1/4 speed as your 60 ft time and you are on the right track or portion thereof"..
Dave
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If your CD and CG are correct and you are not driving over your head, you have a better chance to stay on the track and not go on your head.
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If you use a wheel rate(not to be confused with a spring rate) equal to the corner weight you will usually end up with 3/8 to 1/4 inch travel which is more than enough..
Jack I am with you low is good and small as well. I might add if it has broad flat surfaces on the topside you might want to add 'landing gear' as well. It is a 3 dimensional world at least and you can spin in all planes.. pun intended.. If you get everything else right adding lightness can help a bunch as well. Think of the 1/4 speed as your 60 ft time and you are on the right track or portion thereof..
Dave
Interesting :-). Is this the way Keith's car was setup when it ran so well on the rough track in '05?? Do you feel 3/8 is good for a track that is that bad?? I knew about spring rate of a tire, but this "wheel rate" is new to me. I found the following site that seems to explain it pretty well:
http://www.miracerros.com/mustang/t_wheel_rate.htm
You are correct about the 1/4 speed (speed at the 2 1/4 trap for someone that might need to know what it is). I looked at our runs last year and if we picked up 6 mph at the 1/4 from one run to the another we carried it through the 5 mile, so get your 1/4 speed as high as possible. Don't just think you can run down to the 2 and then get on it.
Thanks and c ya,
Sum
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There was nothing basically wrong with the 05 track only cars and bikes built for a perfect track complaining. Building something that requires a perfect track and not adjustable is silly. Yes I know I am right that is why I offered the info about the quarter speed. Yes ran a setup like that..
Jack I suspect you meant CP and CG.. Cd has nothing to do with it as fare as I ever knew..
Dave
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Ya, dats FARE. lol
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It's all about the 1/4.......Every fast guy will tell you that. Any bets I have made on the salt were 1/4 mile speeds.
When we would watch Al, Nolan, Nish, or Tom run their liners we would wait for the first speed and for the most part knew if we were going to see history in the making.
I believe just the minimal suspension is needed for your vehicle. At the speeds traveled today by the time the vehicle reacts you are another 100 yards down the road so you need it quick and firm. Perfectly round tires are a must especially with a locked you differential. Good Luck
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Please don't tell me I gotta agree with Tone, please don't tell me ! :wink:
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Ask Fogliadini and Ron Jolliffe about the race to the quarter.
Fogie in a GMC 6 '32 five window coupe, Ron in a swoopy '34 Ford roadster with a AA engine.
Fogie won the dollar. "it's all about the quarter, the rest is roll out" Fogie
DW
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One of the finest rememberances I have is the display I made from Fogie and the owners of the BMR Coupe. A total of $2. It is framed and in my trailer. If I can remember, it was whether I could run 196 in the 1/4 after running 190 the day before using high gear only. I ran 202. The plaque was made in their colors of Yellow and Red....................JD
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I thought the old time fast guys didn't believe in suspension.
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rigid up front.... limit to a soft 1" in back.....
kent
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rigid up front.... limit to a soft 1" in back.....
kent
How is your traction with out front suspension? Do you get loose anywhere?
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drives like a cadi...i like it
kent
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drives like a cadi...i like it
kent
hopefully a new cadi, they run pretty good.
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rigid up front.... limit to a soft 1" in back.....
kent
How is your traction with out front suspension? Do you get loose anywhere?
With respect to Kent I don't think you can compare what he is doing with his streamliner to what you are trying to achieve with a car.
Personally I think this is a topic that has no "right" answer. The fastest vehicle in the books will probably be one that is running on a perfect track where suspension is not needed at all. These tracks come along every so often. The fastest vehicle over a number of years where the track varies is probably one that has a working suspension.
With a lakester and anything else where the axles/suspension hangs out in the breeze having no suspension can give you the opportunity for lower frontal area and better aero, so no suspension can give you an edge if you have a perfect track.
I'm trying to set my suspension up where it can be very stiff with a good track and can be adjusted quite soft for a bad one so at least I can still run and get some enjoyment out of a years worth of effort between meets.
c ya,
Sum
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I agree sum.. its better to have it when needed then not have it at all. in my liner i want the front planted and the rear to absorb shocks to the drive line. I don't want the nose to lift, with a suspension, the body can lift before the weight of the wheel assemblies do, sometimes lift to far allowing air under and over or around she goes. It can happen with all those converted door slammers, they drop the car and don't do anything with the original travel. you need to limit the amount of top out to desired ride high only and limit suspension movement to compression only. shocks should be soft compression and slow rebound like a wet road race or dirt track setting. fully adjustable shocks and limit straps are over the counter stuff now a days. In my case i slammed it till it scrapes the loading trailer then went up a little.
kent
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We have no issues with our car and spinning the tires. I just wanted to know other opinions on how and what set ups people are running. We run a 4 link in the back and an A-arm coil in the front. We have run well over 260 many times and have tacked over 300 once until our overdrive broke and still averaged 288 with a blown up motor. Exit speed was 279. We keep getting a little closer to our goal, and keep upgrading the problems we run into. Thanks for all this great info on this site.
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..........have tacked over 300 once until our overdrive broke and still averaged 288..................
What kind of overdrive?? A stand alone or one of the gears in the tranny setup as an over drive?? What transmission are you running??
c ya,
Sum
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the overdrive unit was a gear vendor attached to the back of the tranny. They told us that it was durable up to 1800 hps. Every year at bville something would go wrong with it and they would fix it and beef it up. In 03 when the valve broke the tranny started up shifting and down shifting before the first mile. Anyone want to buy it? Gear vendors fixed it and beefed it up. They were very good to us in that department.
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How are you planning to achieve the equivalent gearing now to get to the speeds you're after?
Pete
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We had an Owens overdrive built to attach to our Owen tranny. Gearing is a little taller than before, I hope the hp will pull the gear.
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Scott Owens builds really nice stuff, but man is he slow. Kind of like Taylor wheels , but then so was Michelangelo. If those three guys built a streamliner, it would look great, run superb, and never be finished........no, wait, thats Marlo's car..........lol :wink:
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Scott Owens builds really nice stuff, but man is he slow. Kind of like Taylor wheels , but then so was Michelangelo. If those three guys built a streamliner, it would look great, run superb, and never be finished........no, wait, thats Marlo's car..........lol :wink:
Ya think? We waited over 3 years for this overdrive from Owens. At one point he lost one of our trannies.
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Sorry to hijack this thread, but I've always liked the look of the Iacanno/Ganahl rail from the 50's, and was wondering if a car like this could be run as a lakester.
http://www.donshotrodpage.net/Pleasanton/pages/XP8240142_JPG.htm
http://www.donshotrodpage.net/Pleasanton/pages/XP8240145_JPG.htm
http://www.donshotrodpage.net/Pleasanton/pages/XP8240144_JPG.htm
If has suspended front suspension, and a solid rear.
Is this set-up do-able on the salt???
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Yes, however this style is a bit dated and may not be competitve against today's records.
Just after moving to Auburn Keith Young teamed with Terry Haines to run a front engine dragster style lakester, GMC/Wayne 12 Port power. Ran at 185 if I remember correctly. Terry now runs a rear engine lakester, blown GMC, 7 port head, over 200.
When my dad passed away there was a picture of me sitting in that car, originally built by Sonny Balcane(sp) at Bakersfield. The car ran in TE that day against Cook/Bedwell. I was 13 or 14 then.
DW
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Yes, however this style is a bit dated and may not be competitve against today's records.
DW
Thanks Dan, but I don't want to be competitive against the U.S. records - I'd set the Aussie record just going through the timing traps :-D ("Big" fish - small pond)
I'd like to know about stability at speed, performance of a solid rear suspended car etc
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..............I'd like to know about stability at speed, performance of a solid rear suspended car etc
It is going to depend on the course. B'ville can change dramatically year to year and even day to day during the event. A perfect track and it isn't going to make a difference. We ran with no problems the first day of Speed Week last year and had real problems getting a hold of the track the last two days. It cost us a new record when the backup run had to be aborted.
2 years ago when the course was really terrible there wasn't many records set over 200. Most of the ones that did set records had a handle on their suspension. Those with non most likely didn't even run.
I'm a big believer in suspension unless you have a car running 300+, but even some of those run suspension. Your not running 300+ the whole run.
Personally I'm trying for relatively soft springs with good dampening. If you can get your tires staying on the course you can transmit power and go faster. If they are in the air you aren't accelerating.
Now the next easy question...............which is better a Chevy or a Ford,
Sum
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Stovebolt,,, now you are talking,,, I like the old vintage rail,,, it may not set a record but it looks cool,,, hmm better wear a stainless steel cup under your nomex underwear !!!! LOL....
Charles
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Sum , you are correct, there weren't many records over 200 in '05. I think there were 1 or 2, but I have been wrong before .We got one of them in our '23 T E/GMR , the little yellow car...Ab Fay drove it to 221 or so. Many have said that car has caddy suspension, it is quite soft compared to many out there. But even with good suspension, Ab said at speed he was being shaken so badly he could barely see the tach. He has a hard time putting his feet together... :-D