One Question!

[nomrlz]

a decent 8.5 will hold what you are building. if you're really serious about goin fast and don't mind doing the work. i'd go 9" if you're gonna change. lotta good advice so far here. follow it and you'll easily be past your goal

[69GMC910]

If I stay with the 8.5, what else besides the non posi guts should be changed? Should the original axles be tossed for something better?
Posted via Mobile Device

[nomrlz]

a 28 spline set-up with good posi would be right on the edge
a 30 spline combo will actually hold good power with a good posi. many people with heavy cars/trucks in the tens on stock 8.5 spline axles. just DO NOT use a gov-lock posi unit. they are junk and will grenade for certain.

[BMERDOC]

Just had a friend at work tell me he hit 12.0 at 116-118mph in a STi Scooby this weekend on all seasons. He dynoed at 375hp to the wheels. AWD doesn't count but the hp/et/mph is a close yardstick.

[Super73]

Originally Posted by BMERDOC

I dont know what your abilities are but I'd say box as much of the frame as you can.

No need to box the frame, it is added weight. Look around and you will find the majority of the 12.99 second and faster trucks run a non-boxed frame. This includes most of the 8-11.99 second trucks on this board.

Originally Posted by BMERDOC

Being leaf spring I'd say add slappers

Caltracs are the better option in my humble opinion. Much more adjustability and better control of the spring.

Originally Posted by BMERDOC

I'm sure someone with Dragtruck experience would have something to say about ballast. Your better starting off with a LWB too!

Originally Posted by BMERDOC

Its all about weight transfer.

How long is a Top Fuel car? Plus the smaller wheelbase and track width the more unstable it is at speed, all else being equal.

I will argue that starting with a long bed will not aid in weight transfer. The added length is in between the front/rear tires, not behind the rear. If you want to talk about the ballast, it moves more weight over the front tires than the rear with the added length.

Top fuel and a street/strip truck are way different. For one, they weigh a lot less and the majority of their weight is on the rear. A top fuel is the length it is to help keep it straight among other reasons. I can name a recent long bed owner on this board running mid 9's naturally asperated that recently decided to turn his truck in to a shortbed. Any guesses as to why?

BTW, here is a quick list of sub 10 second trucks from this board. I tried to find out if they are long/short for you.

Regan - SB (8.93)
Kevin - SB (9.168)
BigJim - SB (9.45) Used to be a long bed
BadGMC - LB (10.11)
Paul1969 - SB (10.37)
71Dragtruck - ? (10.61)
Super - SB (10.73)
Ratpowered72 - SB (10.87)
Drag80 - LB (10.94)
Marv - SB (11.0x)

These 1/8 mile times tell me they would run 10's all day long. You need roughly a 6.95 or faster in the 1/8 to go 10's.

Raddracintrk - ? (6.81 eigth)
KPEZtrk - SB (5.50 eigth)
MSMisserey - SB (4.77 eigth)

Originally Posted by BMERDOC

Two ther things: Lower it to help transfer and always build to be safe. Google "instant center" and read it to se if that will help you.

Sorry, but lowering it does not help transfer weight to the rear tires. Well, it can if done right, but most people lower a truck the wrong way for drag racing.

To add to this, raising your center of gravity actually makes it easier to transfer the weight backwards. The higher it is, the easier it is. One reason guys will jack their motors up as high as they can in their chassis.

Setting instant center should not be done by lowering a vehicle. It should be done by design in the chassis. One of the areas a Caltracs out performs a slapper bar.




I am sorry if you feel I am picking on you by only quoting you. That is not my intention. I am only trying to provide a little better info.

[BMERDOC]

I don't feel picked on, I'm glad you stepped in. I haven't played with American cars in a while and certainly not leaf springs.
I looked up the Caltracs and can't argue at all with them. They look better too. When I said "lower" I meant "correctly with drag racing in mind". When I said "ballast" I woulda hoped someone would have said something about adding weight in the rear for traction. I would argue that instant center can be manipulated through suspension tweaks. I'm stopping there because I feel like I'm either defending myself or may be taken as making excuses. Again, I don't feel like you were picking on me just making some corrections. It is apparent that you have more experience in Drag Trucks than I do but I stand by most of these tips.

[69GMC910]

Thank you ALL for your input.. The best way to learn is from the people who have done or are doing it!!! We can all learn more from each others help on here! I talked with the engine builder today, and he says to push 650 out of the 496 will require too much compression for a 90% street/10% strip motor... He guesstimates 580-600 at the crank for what I'll use it for... I have a TCI T400 lined up, but am still undecided as to what to use for a rear end... The 454 block is coming out of a suburban... I wonder if it has a more desireable diff than what I have now... Also, priced out the cal tracks without a flipped spring... $400 and change... Would flipping the springs be benificial?? ALSO, as I've been a spectator many times at the track, but never raced... THe engine builder said that if I run 11.99, I'll get booted for not having a cage... Is this true? I thought it was 10's... As far as boxing the frame, what exactly does that mean?

[Super73]

Originally Posted by BMERDOC

I don't feel picked on, I'm glad you stepped in. I haven't played with American cars in a while and certainly not leaf springs.
I looked up the Caltracs and can't argue at all with them. They look better too. When I said "lower" I meant "correctly with drag racing in mind". When I said "ballast" I woulda hoped someone would have said something about adding weight in the rear for traction. I would argue that instant center can be manipulated through suspension tweaks. I'm stopping there because I feel like I'm either defending myself or may be taken as making excuses. Again, I don't feel like you were picking on me just making some corrections. It is apparent that you have more experience in Drag Trucks than I do but I stand by most of these tips.

I'm glad you don't. A lot of people would take that the wrong way.

Lowering the front and having it work right is not all that easy. There are few to no off the shelf springs for our trucks that work well for drag racing. You have to ask lost of questions and figure things out. Most lowering springs are waaayyyy too stiff for a drag racing application. Check out the suspension 101 thread I started some time ago for more info.

Moving weight around is always better than adding weight. But in some cases you need to add weight. I ran a tailgate that I added 100lbs to for a few years. But that was after moving the batterey to the back, putting a cell in the rear, ect.

I completely agree ICG can be adjusted through suspension tweaks, but not just by lowering. Moving Shackle height, front mount height, the hole on the caltrac's ect. The point I was trying to make was that simply lowering a vehicle to adjust ICG can do more harm than help. But adjusting the suspension geometry itself, well, that puts you light years ahead.

Originally Posted by 69GMC910

Thank you ALL for your input.. The best way to learn is from the people who have done or are doing it!!! We can all learn more from each others help on here! I talked with the engine builder today, and he says to push 650 out of the 496 will require too much compression for a 90% street/10% strip motor... He guesstimates 580-600 at the crank for what I'll use it for... I have a TCI T400 lined up, but am still undecided as to what to use for a rear end... The 454 block is coming out of a suburban... I wonder if it has a more desireable diff than what I have now... Also, priced out the cal tracks without a flipped spring... $400 and change... Would flipping the springs be benificial?? ALSO, as I've been a spectator many times at the track, but never raced... THe engine builder said that if I run 11.99, I'll get booted for not having a cage... Is this true? I thought it was 10's... As far as boxing the frame, what exactly does that mean?

Learning is what this site is for.

Talk to your local track for cage requirements. NHRA is 11.49 for a 6 point. If they run a different sanction, there could be different requirements.

[djracer]

I am gonna be swapping my son's 70 leaf truck to trailing arms and coilovers so it won't be real low. I am gonna try to lower the front with just springs when I get the front where I can weigh it.

[69GMC910]

My engine builder/ driveline installer is telling me upwards of $3000 for a darn good rear diff/axle setup. Does that sound extreme?
Posted via Mobile Device

[djracer]

Sounds a little high to me.

[nomrlz]

Originally Posted by 69GMC910

My engine builder/ driveline installer is telling me upwards of $3000 for a darn good rear diff/axle setup. Does that sound extreme?
Posted via Mobile Device

if by darn good he means "last you'll ever need to buy" then that is spot on.

that is top-o-the-line nine inch money there

[69GMC910]

Thats 12 bolt building price... I was thinking 2200 max...
Posted via Mobile Device

[ItsRandy]

Originally Posted by 69GMC910

My engine builder/ driveline installer is telling me upwards of $3000 for a darn good rear diff/axle setup. Does that sound extreme?
Posted via Mobile Device

That's about what I paid for a brand new Strange 9" with 35 spline axles, Detroit Locker, nodular iron center section, 1350 yoke and Wilwood disc brakes including shipping to California.

[69GMC910]

Where did you buy from? Sounds like a KILLER setup!
Posted via Mobile Device

[nomrlz]

Originally Posted by ItsRandy

That's about what I paid for a brand new Strange 9" with 35 spline axles, Detroit Locker, nodular iron center section, 1350 yoke and Wilwood disc brakes including shipping to California.

bingo! paid about the same for a mosier set the same a couple years ago

[ItsRandy]

Originally Posted by 69GMC910

Where did you buy from? Sounds like a KILLER setup!
Posted via Mobile Device

Directly from Strange Engineering.

Who is Kenny Powers?

[Marv D]

Originally Posted by 69GMC910

... THe engine builder said that if I run 11.99, I'll get booted for not having a cage... Is this true?

Are you talking a NHRA track???? IHRA has their own rules and they do vary in some areas, but generally I recall them aligning with NHRA. So that would be the only caviat.

I ABSOLUTELY question this guy's expertise now. And for NHRA tracks, In a word.... NO,, 11.49 you need a 5pt. ROLL BAR,, 9.99 you need a cage.


Look, at 3380 pounds I've been 12.teens @ 110 with a 480HP SMALL BLOCK through the mufflers and pump gas. Of course weight is your enemy and you are going to need to put the truck on a diet. But if this clown can't put you SOLIDLY in the 11's with a pump gas big block,,, you need a new engine builder!!!!

[1Bad62Pro/Street]

Competition Engineering Tech Article:
http://www.competitionengineering.co...es/chassis.asp

Getting more power from an engine is something all racers are familiar with. Getting that power to the ground, however, is a science that few racers really understand. For those of you just starting out in drag racing, we’ve put together a basic overview of how chassis and suspension systems are affected by sudden acceleration. The Chassis PeopleTM at Competition Engineering want you to understand the relationship between engine power and the chassis, suspension and driveline systems of your car. By doing so, you will be in a better position to select equipment that allows you to hook up and lower ET’s!
Without the right chassis and suspension setup, all the horsepower in the world will only go up in tire smoke! As you’re trying to understand how modifications to the chassis and suspension systems improve traction, it helps to keep one thing in mind. Power produced by your engine must take a direct path to "planting" the tires and "launching" your car forward. Any power that gets absorbed by the chassis and suspension is power that can’t be used to get you to the finish line as quickly as possible.

There’s a basic law of physics that states "for every action there is an equal and opposite reaction." Relating this principle to a game of billiards is relatively easy. But applying it to chassis and suspension systems on a drag race car is more complex. When trying to understand how chassis and suspension setups affect traction, keep the "action/reaction" concept in mind. It will make things much easier to understand.

While race cars are designed for racing, street cars are designed primarily for carrying passengers safely and comfortably. From the factory, passenger cars are not equipped to handle high rpm launches from a standing start. This instant release of power places great strain on stock suspension systems and usually results in unwanted wheel hop, tire spin and parts breakage. Controlling this unwanted reaction is the job of a traction device, which limits the rotation of the rear axle housing and transfers forces to the track surface.

For example, the installation of traction bars is a popular way of limiting rotation of the rear axle housing. Traction bars mount directly to each side of the axle housing and extend forward like long arms or levers. When the housing begins to rotate during initial launch, the traction bars stop this action, holding the housing in place and converting some of the applied torque to a force which pushes the rear tires into the track surface. By stabilizing the axle housing, wheel hop is virtually eliminated, acceleration is smoother and parts breakage is minimized.

[1Bad62Pro/Street]

Rule books can be found in each website.
IHRA
http://www.ihra.com/
NHRA
www.nhra.com/
NMCA/NMRA
www.nmcadigital.com/
ORSCA
http://www.outlawracing.com/forums/

[69GMC910]

Kenny Powers is from the best television show ever!!! HBO's Eastbound and Down!!! And I know the engine builder races in NHRA, so I assumethe mechanic that gavr me the 11 second talk misunderstood the engine guy...
Posted via Mobile Device