Landracing Forum
Tech Information => Steering - Suspension - Rear End => Topic started by: Plainview on March 26, 2008, 03:30:14 PM
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We just started a Classic Gar Coupe project for Bonneville 2009. We are going to use a Mustang II IFS that has been re-enforced and strengthened enough, we hope for the rigors of Bonneville. Are we going down the right path? Or should we be looking at replacing the front end with a stronger Camaro front clip(more expensive and time consuming). The Mustang II IFS we will be using, will be done by a noted West Coast Bonneville racer shop. The plan is to use a big block GM motor ( 672 c.c.) unblown. Any suggestions on would be recommended for a rear-end set up? We currently have a 9-bolt Ford rear-end with a Strange center housing. The rear-end is a leaf spring arrangement, and we are thinking of just using a 4 link set up. Good idea or bad?
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We just started a Classic Gar Coupe project for Bonneville 2009. We are going to use a Mustang II IFS that has been re-enforced and strengthened enough, we hope for the rigors of Bonneville. Are we going down the right path? Or should we be looking at replacing the front end with a stronger Camaro front clip(more expensive and time consuming). The Mustang II IFS we will be using, will be done by a noted West Coast Bonneville racer shop. The plan is to use a big block GM motor ( 672 c.c.) unblown. Any suggestions on would be recommended for a rear-end set up? We currently have a 9-bolt Ford rear-end with a Strange center housing. The rear-end is a leaf spring arrangement, and we are thinking of just using a 4 link set up. Good idea or bad?
Welcome to LSR and I don't see anything wrong with your plans. What rpm with the motor?? We run a 2.47 gear in Hooley's Stude, but this last year went to a G-Force transmission where we can setup one gear as an overdrive and currently do that with a 7% overdrive in what was 3rd, but is now 4th. What kind of speeds would be your goal?? Hooley runs a Mustang type front suspension that he built and it has worked fine. Put limit stops on it. You might be able to get some ideas here:
http://purplesagetradingpost.com/sumner/hooley/hooley-index.html
There are some construction pictures there.
Good luck,
Sum
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There is nothing wrong with leaf springs on the rear. On my MS I use leafs to hold the car up and keep the rear axle in place. Then I use air bags to get up to ride hight. Air bags smooth the ride a bunch. You can hook up a pressure gage to the air bag and see if you have down force or lift on the rear. I use air bags on the front for the same reason but with a straight axle.
Doug Odom in big ditch
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Just a brief introduction. My partner (38 yrs old) and I (62 yrs old) are both former drag racers. We both have had the bug about Bonneville for as long as we can both remember. Bonneville is a totally different game. According to the rule book the current record for AA+ Classic Gas Coupe is 188 mph by Utah Valley State. It must be a class project ( better then metal and wood shop in H.S.). Our goal is 200 mph and our primary goal in 2009 will be just a shakedown of the car. We haven't plugged all the variables into a formula yet to determine whether that speed is attainable. Most of the records below AA Classic Gas Coupe are already at or over 200 mph. Does anyone know what make and model car the current record holder is using?
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Welcome aboard, sounds like a fun project. What area do you live in, it helps to know as we know racers all over the country and there could be someone close to you that can answer some of your questions. :?
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The Utah Valley State car, #396, was a 69 El Camino with a 572" Chevy motor according to the 2007 SpeedWeek program.
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Welcome to the group, you'll have a blast racing at the salt. Sounds like you have everything planned right and in order. One thing to keep in mind is IF you're thinking of the Bonneville 200 mph club at some point that the minimum speed for entry into that club is 235 mph. You can set records and have a good time but if the 2 club is in the back of your mind that's the boggey...... not trying to disapoint just letting you know.
Good Luck & have fun!
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Yes, we understand the 200 mph club is a bit different then setting records. We live in both the Austin Texas and Dallas Texas areas' (in response to a previous post). I am quite interested in the topic of air pressure coil suspensions for the front and rear. The Bonneville rule book made no mention of them. Can I assume they are used safely on cars' at Bonneville?
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There is nothing wrong with leaf springs on the rear. On my MS I use leafs to hold the car up and keep the rear axle in place. Then I use air bags to get up to ride hight. Air bags smooth the ride a bunch. You can hook up a pressure gage to the air bag and see if you have down force or lift on the rear. I use air bags on the front for the same reason but with a straight axle.
Doug Odom in big ditch
I split all the transducer part of this thread off and moved it to........
http://www.landracing.com/forum/index.php/topic,3748.0.html
........... "Transducers to monitor lift and downforce" in this part of the tech section,
Sum
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There is nothing wrong with leaf springs on the rear. On my MS I use leafs to hold the car up and keep the rear axle in place. Then I use air bags to get up to ride hight. Air bags smooth the ride a bunch. You can hook up a pressure gage to the air bag and see if you have down force or lift on the rear. I use air bags on the front for the same reason but with a straight axle.
Doug Odom in big ditch
There is probably more than one way with air bags where the pressure could be used as feedback for some form of active suspension that adjusts ride height and attitude on the fly. For example, perhaps pressure from the air bag could be fed into a bellows that in turn opens or closes a valve.
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Semi-trucks and trailers have been using this type of system for years. Some even have a scale built into the trailer/tractor to allow easy reading of the weight of the load. Oughta be pretty easy to find in the trucking literature.
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Plain.. Good luck with your project. If you are looking to be competitive for a class recod make sure you meet the rules. In gas coupe the frame must remain the same year as the vehicle. It has meant the frame rails for all the years I have been in the organization. That would mean no welded on front clips like a Camaro which is about 1/3 of the frame. Many are and have used late model style IFS and coil rear suspensions. Notching a frame rail at the rear to get it lower is also "not stock".
As one who has drive an earlier vehicle over 150 there is a big vacuum spot behind the rear window where it meets the trunk line. A 54 Chevy is pretty harsh there and lift happens where the body line doesn't flow like a 37 but is harsh like a 39 up. There are some relief devices like the ones used with a Studbaker and the rear spoilers to help them stay on the ground...Good Luck
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J.D.
You mention "vacuum relief devices" and spoilers.
What did you have in mind? and Would they be legal in Gas Coupe class?
Will6er
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In the past prior to all the stuff guys hang on the back of their Studes they ALL had to add "air ducts" because they spun at 185 without them. They were all done differently. Typically a 30 to 36" x 2 to 3" rectanglular duct went between the area behind the rear window at sightly forward angle through the floor board. This let air out from under the car and up through tha duct breaking up the vacuum area. I've seen multiple 2" round tubes and 2 shorter rectangles. The definition is on page 37. Today a lot of guys add a lot of weight also.
You will notice that in the Gas Coupe section that ther are not mentioned in the "not pemitted" paragraph on page 66.
As for spoilers you need to contact the Coupe and Sedan committee chairman to see if what is described on page 42/43 is allowed. They were not in vintage where I was competing...Good Luck
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No add on spoilers in gas coupe unless it came stock with one. As far as the ducts in the body, that would be considered a body mod which is also not allowed. At least that is the way I take the gas coupe rules. May be Dan can elaborate.
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Thunder and Plain. I think you will see that an "Air Duct" as defined in the rule book is allowed in Gas Coupe. For the last 35 years I have been the association the were not a body modification. Bruce Gieslers "Hanky Panky" #219 53 Studebaker has one and runs in gas coupe and has for over 40 years. I almost put one in my 1940 Chevrolet after I ran over 150 and the rear became very light.
If you believe they aren't I would contact the head of the Coupe and Sedan committee chairman. I would also use this car as an example. I could be proven wrong on this but with Bruces car as an example I believe I'm correct. It is always best to call these Committee people that's what they are for. If they are not legal I would not want to be the one to tell Bruce.
These devices are not as popluar as they once were and that maybe because of the more aero-dynamic bodies available and the running of cars in Altered which allows the spoilers. . . . JD
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Thunder: I have reeread the section on streamlining 4CC and an air duct is definately part of that definition for directing air through the vehicle. Funniy thing is 4CC.7 thru 4CC.9 does not mention the air duct specifically but everthing else listed in streamlining.
What else is funny is the air duct or streamlining is not even mentioned in Altered either. I am positive I have seen air ducts exiting behind the rear window in both altered and gas coupes. Gas roadsters say they are specifically allowed and Production and GT specifically forbid them.
These were put in for safety reasons back in the 60's. Perhaps a specific air duct exiting behind the rear window should spelled out; differentiating it from one on the side of a rear engine modified roadster to allow air into an intake.
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Yeah. I re-read it several times and get the same conclusion. :?