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Is there an advantage to a concrete filled bumper ?

Discussion in 'The Hokey Ass Message Board' started by swade41, Sep 25, 2010.

  1. I'm building a 3 inch tube rear bumper for the street/strip 41, about 52 inches long and was thinking of filling it with weight. I was wondering if anyone has ever did it and their results of the effects. Will the extra weight offset the extra traction it may provide ? What help would it provide, a tenth or two on a guess ?
    Here's the truck, bbc,th400, leaf spring rear.

    Attached Files:

  2. Ruiner
    Joined: May 17, 2004
    Posts: 4,145


    Either make 2 bumpers or make the weight removable and test it out on your truck...there's a lot of variables with each different vehicle, so nobody can give you a definitive answer...test and tune, that'll be your best guess is the extra weight will be a pain in the ass on the street...
  3. 61falcon
    Joined: Jan 1, 2009
    Posts: 772


    the exrtra weight will slow it down. it will launch plenty hard with the correct setup rear suspension.
  4. RichFox
    Joined: Dec 3, 2006
    Posts: 9,946


    Do you need the weight to make class. No. All that ended 40 years ago. If you must go against Newton's laws fill it with something easy to get out. Water.
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  5. fortynut
    Joined: Jul 16, 2008
    Posts: 903


    :DJUST A THOUGHT, but Concrete seems permanent. If I wanted to add weight that I could remove, or adjust, I'd just use lead. Ingots of any size can be cast into known amounts that could be bolted down. You could adjust according to conditions, or remove entirely.
  6. switchkid0
    Joined: Dec 2, 2008
    Posts: 145


    Sorry if this strays a bit from the original post, but has anyone else ever run across an engine block that was filled with concrete? In the mid-eighties one of our racing buddies bought a BBC that had been filled. Nobody was running coolant with injection at that time, but I still thought it was odd that someone had taken the time and trouble to fill the water jackets with slurry. If I remember correctly, he ran it until a rod got into a sleeve, and then junked it, because nobody wanted to bore it.
  7. blt2go
    Joined: Oct 27, 2009
    Posts: 551


    i know it's a cat of a different color, but when we used to run dirt track i built a bumper and fitted it with removable lead slugs cast from a piece of the tubing i made the bumper out of. we could add/remove as needed. good luck.
  8. Kevin Lee
    Joined: Nov 12, 2001
    Posts: 7,409

    Kevin Lee
    Super Moderator
    Staff Member

    Don't listen to these other guys... there is PLENTY of advantage. Oh wait... you mean for you?
  9. I'm pretty sure you know why the 60's gassers had threaded pipe and caps. The concrete seems too permenant just like fortynut suggests so trial and error may be the way to go.
  10. carcrazyjohn
    Joined: Apr 16, 2008
    Posts: 4,844

    from trevose pa

    Either water or sand ,
  11. I thought once was I welded up the bumper it would be closed for life. I'm putting a bologny cut on the ends and capping them off so the ends won't be removable.
    I was fighting traction issues with my t-bucket and dropped from 4.11's to 3.25's and it picked up 3 tenths in the 1/8. It's not to often you here of people picking up when dropping gear.
    I'm just planning ahead here and trying to offset the weight of that big block. Who knows it might not spin at all, but I just figure it will.
  12. G'day, A friend of ours ran a mod prod car back in the 70's. The best times he ever had were on the day that he forgot to take his toolbox out of the trunk. Great 60 foot times.

    As far as concrete in the block, our current ot drag car runs a very over-bored bbc. It has "hard block" up to about 3" from the deck. I think it was a Moroso product.

  13. David Chandler
    Joined: Jan 27, 2007
    Posts: 1,101

    David Chandler

    It would make in impression on the guy who rear ends you!

  14. God i love a smart ass :D.
  15. Francisco Plumbero
    Joined: May 6, 2010
    Posts: 2,536

    Francisco Plumbero
    from il.

    You need to be more precise, leave your bumper alone, you need to make a spot to load counter balance weight to the car. I'll use an example, you weigh 200 lbs, the car is loaded to the left side by 200lbs, you need to load 200 lbs to the right side to balance the car, next to you. At the back of the car you may need more or less so you make a system to load and unload weight from the chassis on the rear of the car on both sides, you have to tweak it to get a nice straight launch. Look through some national dragster issues for a system or pick up a copy of Alstons drag race chassis manual. Should be some info to help you set the chassis up to bite.
  16. Sounds in the center on top (to fill) and bottom (to drain) drill a hole and tap it for a recessed head brass (so it won't rust in) pipe plug. Paint the plug the same color as the bumper. Use a yard sweeper nozzle to fill with water from the garden hose. TaDa!
  17. chevyshack
    Joined: Dec 28, 2008
    Posts: 950


    4.11's will make you spinn pretty good unless you have the right suspension set up and tires to hook it up. If you want a better time play around with diffrent hight tires and air pressure. Put a smaller tire on then a taller. Its kinda like a poor mans gear swap. Also 4.11's will have you winding out at the end of the track. Maybe not so much on an 1/8th mile but ive always ran 1/4. My 3.73's wind out pretty quick. I need an extra gear like an over drive.
  18. chevyshack
    Joined: Dec 28, 2008
    Posts: 950


    Oh yea. I wouldnt do the cement thing unless your building a demo car. Try pre loading your suspension for better grip. They have an air bag that fits between your coil springs in the rear or on top of your leafs depending on what suspension your using.
  19. RichFox
    Joined: Dec 3, 2006
    Posts: 9,946


    To the guy who asked, Yes I have used Hard Block in race motors. Your bores will be noticeably rounder after boring and your leak down improve a lot. I think it's the same stuff they put in milling machine bases to keep them from being top heavy.
  20. I used to Dave Morgan's Dorr Slammers the Chassis Book but loaned it out and never got it back.

    These tires are kinda big it would be a 14 X 32 size in slicks, but are M/Ts. Kinda expensive to have a few sets laying around to switch. The truck has a 3.89 gear in it now but the tire is 33 inches tall.
    I've been around drag racing for a while but just wanted to hear from someone if having a heavy rear bumper helped or not.
  21. mustangGTS
    Joined: Sep 18, 2010
    Posts: 28


    Several issues here...

    Weight is lost performance. Traction has very little to do with weight in general, and more about placement of weight in reference to instant center. Steel, or lead plates, with all thread attached to the chassis in different locations will help, but proper chassis setup, and some adjustable areas will gain you more overall performance. Change your shackles, and get some degree wedges for under your perches to keep your pinion angle correct. Most of all.... have fun doing it! Caltrac bars are a big help and can be removed fairly easily.
  22. Larry T
    Joined: Nov 24, 2004
    Posts: 7,680

    Larry T

    These tires are kinda big it would be a 14 X 32 size in slicks, but are M/Ts. Kinda expensive to have a few sets laying around to switch. The truck has a 3.89 gear in it now but the tire is 33 inches tall.
    I've been around drag racing for a while but just wanted to hear from someone if having a heavy rear bumper helped or not.[/QUOTE]

    If you run slicks, I think the compounds are sticky enough that the weight wouldn't help. But if your Mickey Thompsons are the old Sportsman you need all the help you can get. I ran a set of 19.50's and never could get them to hook up on my 34 Int pickup.

    Kind of interesting that (in the 1/8) it ran low 8.00s with the MTs, 7.40s with 14 X 32 slicks and 7.20s with 10.5 X 30 slicks. You can get too much tire on a car.
    Larry T
  23. Yup these are the Sportsmans and just farting around with the truck I see they won't hook, the reason I started the thread. I could overcome looks for a smaller tire at the track but it would sure look funny way in there with that narrow rear. Thanks for posting the numbers of the different tires, puts it all in black and white.
  24. TrannyMan
    Joined: Dec 3, 2005
    Posts: 473


    Uh, no. don't. Unsprung weight is bad. Get yourself a weight box if you must have weight for traction.
  25. xracer40
    Joined: Jun 20, 2010
    Posts: 307


    A general rule of thumb in drag racing is the 10/10/100 rule. 10HP,tenth of a second,100 lbs.
    +or-100lbs.=+or- 1/10 of a second
    +or-10HP =+or- 1/10 of a second
    This rule applies to the acceleration of the vehicle. Adding weight for traction is a another matter. Depending on the vehicle,often times adding weight in the proper location for traction will more then offset the disadvantage of adding weight versus acceleration.
    In drag racing the first 60 ft. is where it is at(think traction and weght transfer) then worry about acceleration(think the 10/10/100 rule).
  26. newsomtravis
    Joined: Jun 1, 2009
    Posts: 562

    from pville, ca

    use lead, since you are cutting the ends off the bumper, make you some lead slugs that will fit inside in a few different weights and u can remove replace as u see fit, like hockey pucks is what i`m thinking, then a bolt all the way through each end, kinda what i did in my stockcars, hollow frame rail, had 12 lbs leads and could adjust bolt across end of rail.....but it was on the left side.....
  27. 45_70Sharps
    Joined: May 19, 2010
    Posts: 331


    Right concept, wrong mineral.
    Have you priced lead today?? Very expensive.
    Need a cheaper filler if you were to add weight.
    Water is good and ways to add, take out are covered in the thread.
  28. 56oldsDarrin
    Joined: May 9, 2009
    Posts: 396


    I heard stories about some family member putting concrete in BOTH bumpers. But that was circle track.
    It supposedly would just blast other cars off the track, then blow a tire and crash.
  29. Shaggy
    Joined: Mar 6, 2003
    Posts: 5,208

    from Sultan, WA

    try a 64 el camino, i spin tires at any speed 60mph or over on every bump on wet backroads
  30. Hotrod7
    Joined: May 21, 2009
    Posts: 155


    Back in the day my dads injected alcohol bigblock elcamino would get 392 heads stacked up in the bed at the drag strip to get it to hook up. Different times :eek:

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