Belly Tank Build Diary

[bubruins]

I think the question of tire deformation has a lot to do with it - and most of us run 90psi tiny contact tires.
For two points of trivia in this thread (about a lakester focused on asphalt) - can Sparky and JAL comment with vehicle weights?

I tend to agree with Sparky that the reaction time of suspension creates a scenario where even a finely tuned system has a hard time meeting the traction needs. Aero providing downforce is a win/win with the only downside being air resistance. If you need the grip more than you need the efficiency to get the maximum speed in either the mile or the 5 mile... adding a wing or engineering for downforce seems like a no brainer. With the tires on Mike's lakester I doubt oscillation will be nearly the issue it can be at Bonneville.

[JAL AKA JL222]

I think the question of tire deformation has a lot to do with it - and most of us run 90psi tiny contact tires.
For two points of trivia in this thread (about a lakester focused on asphalt) - can Sparky and JAL comment with vehicle weights?

I tend to agree with Sparky that the reaction time of suspension creates a scenario where even a finely tuned system has a hard time meeting the traction needs. Aero providing downforce is a win/win with the only downside being air resistance. If you need the grip more than you need the efficiency to get the maximum speed in either the mile or the 5 mile... adding a wing or engineering for downforce seems like a no brainer. With the tires on Mike's lakester I doubt oscillation will be nearly the issue it can be at Bonneville.

  The 222 Camaro weighs at least 5200lbs race ready. Years ago, I had a time slip of 280 mph at the 21/4 and 294 in the 1st mile where it developed a major oil leak from a rod exiting the block

  Data log only showed wheel spin when I gave it to much throttle shiffting into 3rd, able to full throttle in 4th, loging showed no wheel spin.

  55% of weight on rear wheels  car has a 4 link which I have adjusted for more weight transfer since the above run. Resulting in a record 252mph run at El Mirage in 2024 [1I/3 miles] and 287 mph in the 21/4 last August at Bville last August with another oil leak

We run the 10 inch wide Taledaga type tires [ fat tires ] 

    Imagine running 90 lbs of air pressure at a drag strip  Spin city,  Bville worse.

     Hey Sparky what's your best 21/4 time


                                     JL222

Correction 65% on rear wheels not 55%  :-P

[bubruins]

Thats an impressive speed at any distance but I think SPARKY will want to compare the 5 mile lol. I think the 5200lb and 10" tires at lower pressure make it difficult to compare the oscillation at the center of the controversy here.

[SPARKY]

they varied but the farther they go down the track the more distance   some were 15 to 20 feet some were much longer but what surprised me was the distance between the ones on the left and the right side were very near the same--I deducted that could only be from an oscillation of the rear axle  most likely the frame on a non sprung car

[SPARKY]

my best 21/4 was 267. but remember I was running a PG with 1.76 first and 2.14 RA.  My FDRs were 3.76 2.14 1.66 no torque converter   my eng didn't start to wake up until 4700  so at first i didn't accelerate very fast so I only picked up 40 mph in the next 3 miles

I now run a 5 speed air shift trans with a GV which give me 6 speed still can never lift to shift and my first shift is the GV  now less that 1800 rpm drop instead of 4000 on the first shift and a 2.26 RA and a eng. who's peak TQ is where my peak HP use to be. so I am shooting for 275 1/4  but I doubt we will ever have as goo a track as we had in 2008

[JAL AKA JL222]

they varied but the farther they go down the track the more distance   some were 15 to 20 feet some were much longer but what surprised me was the distance between the ones on the left and the right side were very near the same--I deducted that could only be from an oscillation of the rear axle  most likely the frame on a non sprung car

  Using the formulae mph x ft per sec [1.466]   a race car would travel 220 ft at 150mph.

  So 1 oscillation at 220 ft in one second two in half a second three in 1/4 second. Even quicker as distance shortens between spin marks.

  Not likely.

Sparky says he experienced this himself, but he has a video showing more salt spray from one tire and not the other.  But no oscillation.

  I have 3 books on chassis set up and remedies for problems.

  Not a word about chassis oscillation.

  Sparky would have us believe a chassis oscillates so much one wheel comes off the ground!!

                               JL222
                     

                 

             

 

 

[37 ROADSTER]

How many of your books deal with set up for land speed racing. Drag race set up is different than sakt or dirt, traction is not the same so your car will react differently.

[desotoman]

I googled the question and here is the answer the assistant gave me.

Search Assist

Yes, chassis with high horsepower motors can experience oscillating twist due to the significant torque produced by the engine, which can lead to flexing in the frame. This twisting can affect the vehicle's handling and stability, especially under heavy acceleration.
corvetteforum.com ls1tech.com

Tom G.

[JAL AKA JL222]

How many of your books deal with set up for land speed racing. Drag race set up is different than sakt or dirt, traction is not the same so your car will react differently.

The 222 chassis is an Alston Pro Stock Chassis. Seems to work pretty damn well. I have changed to 450lb rear spring springs from the 130 lbs because the car weighs twice as much as a 2250lb pro stock. We have a water tank and big intercooler tank and to weight boxes with batteries on top, 3000 LB on rear tire. The drag books deal with weight transfer, 4 link settings, contact patch chassis alignment, how to check it and adjust, bump steer, toe in, brakes, parachute mounting, gas petal ratio, traction and handling problems and how to fix them, all useful at Bville or El Mirage.

  One of Carroll Smiths books deals with racing in the rain due to less traction and load transfer. Bville?

     Carroll Smith   '' So the directions in which to move to set the car up for rain are pretty obvious.''

  Softer springs, softer bars, softer shock setting and more wing'' and more on brake pads ECT for road racing.

  So a lot of info from these books have been applied to the 222 Camaro and would be helpful to Bville racers.

    Some of the high-powered cars with narrow tires shed their tires on a run but we have made some high speed runs with our 10'' Talladega's where the tits were still there.

         JL222  HAPPY NEW YEAR EVERYBODY: cheers:

 

   

[SpeedRacer93]

What type of "bumps" are you trying to deal with, 1/8 inch ripples, 1/2 inch washboard, 1 inch, or 2 inch ruts?

At 200+ mph is the suspension mechanically able to respond to them?

At 200+ mph don't you agree the suspension is acting more as a high frequency vibration damping system vs standard car bump compliance suspension?

For a suspended car isn't the oscillation controlled by the shock?

[SPARKY]

guys  I was just trying to say I had a very ill handling race car  I found several thing that helped:

# 1 & 2.  got rid of scrub radius and caster that was changing the weight on the drive tires when I turned the steering wheel as long as I had a bunch of caster.

# 3 kept adding cross bracing until I had a very stiff chassis.  I verified by how far the RR wheel was off the floor before the RF tire lifted
     ( after I made the front axle solid and made a new front axle out of 1/2" side wall tubing which now had very little deflection

# 4  The Torsen  helped the car in stability and acceleration by keep the forward TE by both tires maximized for traction and power available

#5.  I tried to counteract the torque of the drive shaft trying to spin the axle counter clockwise --by redneck engineering
        the rr axle mounting so it preloaded the chassis to make the RIGHT rear wheel weight more

The bottom line was car nor I were near as busy as during a pass

[desotoman]

Sparky,

Thanks for posting the problems you encountered with your racecar, and how you improved the handling of your car.
I appreciate your posts.

This sport is not a cookie cutter sport. We all have different ideas and theories on how to go fast, and build our cars accordingly.
With that in mind, what is good for one persons vehicle, is not necessarily good for another persons vehicle. But it is great food for
thought, and makes us think.

Sharing ideas and thoughts are a great plus for this sport.

Thanks,

Tom G.

[Mike Brown]

What type of "bumps" are you trying to deal with, 1/8 inch ripples, 1/2 inch washboard, 1 inch, or 2 inch ruts?

At 200+ mph is the suspension mechanically able to respond to them?

At 200+ mph don't you agree the suspension is acting more as a high frequency vibration damping system vs standard car bump compliance suspension?

For a suspended car isn't the oscillation controlled by the shock?

The bumps that I experience are the "expansion joints" between the sections of concrete.  I have not measured the joints, but best guess is that they are not offset more than 1/2", I will measure them in May.  They do show up on the vertical accelerometer of my data logger.  They can upset the car, unloading mostly the rear tires under acceleration.  I do believe that the shocks dampen chassis oscillation but the suspension does offer some compliance over these bumps.  I know that the suspension does respond to the bumps, how quickly I could not quantify.  Remembering that in mile racing my "first" mile is all acceleration and speed is measured in the trap at the end of the mile.  I am traveling at 200 mph for a very short time.  I shift into high gear at between 175 & 180 mph at the half mile so my suspension needs to work well up to that point.  How effective it is in the last half mile I cannot quantify.  I run rubber springs with about an inch up and down of travel.  The rubber springs have some natural dampening qualities that my chassis likes.  A few pages back in an effort to increase the rear wheel traction I reported switching to soft coil over springs and double adjustable shocks at the recommendation of a manufacturer's application engineer.  This was a total failure yielding a very poor handling (slow) car.  Looking back this was probably exacerbated by how narrow my spring/shocks are located towards the center of the car.  The car was torque steering.  There is so little room inside a belly tank that I decided to not add a sway bar and went back to the rubber springs keeping the double adjustable shocks.  That still left me wanting more traction in the rear of the car which started me down the path of a wing. 

[Mike Brown]

I received a private message from a racer that I hold in high regards.  This person has many records, some over 400mph.  I will not post his entire message but this portion of the message was an encouragement to me with regards to this project and explained drag verses inertial resistance. 

Message,

"2) You are on the right track with the wing to produce traction with a light weight vehicle. Typically the induced drag of the wing and support(s) will be significantly less than the inertial resistance of a comparable amount of ballast weight, and you have also recognized that ballast in the rear for traction must be proportionally matched with ballast in the front to maintain yaw stability, but providing no traction gain along with its inertial resistance. As acceleration rates increase on the higher traction paved surfaces this benefit of wing down load over ballast inertia becomes greater. You never see ballast added to a top fuel car to improve traction!"

[SPARKY]

   Mike please describe the torque steer

Tom.  that is what this website has also brought to the sport  I sure hope Jon finds some one who will be able to keep this website going to:
To honor what John Amo started and Slim has so greatly continued   Protect your Legacies  Jon   find someone!!!!!!!!!!!!!!