Drag racing traction secrets?
 

Anyone have some good ones? I'm having trouble hooking up at the track. No wheel hop, just spinning. This is with 235 60 15 MT drag radials.

Are you lowering your tire pressure before you burnout. And what kind of suspension are you running in the rear.

I bet you're running more than 20psi of pressure?


-Ted

try n use some vht

Get rid of the V8. How dare you have torque in a 7! :)

^ Too bad there isn't a V8 to get rid of... the GN engine is a turbocharged 3.8L V6.

Shhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh.

:fawk:

My knowledge begins and ends at rotaries.

well, your first mistake when it comes to wanting traction was puting a GN motor in there. Way too much torque for a little rx7. You could use some VHT like previously stated. You could also try to get some bigger gears(smaller number). Like mabey some 3.50s or 2.somehtings.

I always thought "bigger" gears meant numerically higher?


Wouldn't doing that makes it easier to spin the rears assuming torque isn't the limiting factor?


-Ted

Yes I'm lowering my tire pressure around 15psi. I've been down to 12 but it didn't help. Also doing a burn out or not going around the water box or through it. All resulted in the same thing.

Suspension is all OEM. Old worn shocks, original springs. Doing a a burn out as well. And the track is sprayed with VHT.

The whole car is to light for torque is a bogus statement. Theres a ton of cars making more hp than I am and alot lighter. This car i sno light weight it's 2830lbs! About the same as a gutted mustang. And they cut 1.5x 60"s all day long with the same tires as me.

I'd love to change the rear gearing but unfortunatly tmazda doesn't make after market gearing for FC's that lowers the gear ratio. 3.90 is as low as it gets and thats what I have. I used the calculator and a 3.09 would be a perfect gear for my car.


I was looking today and it looks like my right rear shock might be blown as well... I woulld guess having a blown shock would help more than hurt. But I'll replace it anyway.

Any other ideas? Several of the v8 ls1 guys are cutting 1.4's with the same tire and suspension setup as me. My camber could be the problem but I really doubt it!.

how about launching lower and rolling into it? What is your launch rpm? using a 2step or anything? auto i take it? stall? So many variables to play with. With that small of a tire you're gonna be limited to how much power you can apply at the starting line obviously. Just start as low as possible rpm wise and sneak up on it.

A little list of things to consider:

Turbo sizing could be bringing it on too fast.
Stall could be too tight.
Gearing could be wrong.
Tire size could be too small.
Rpm could be too high at launch.

Your tire pressure sounds about right for drag radials although we've had luck as far down as 12psi. I would just set it around 13-15 and don't touch it until you have everything else figured out.

Do they make a taller tire that you can still fit? might fix the problem right there.

The 235 60 seems to be the tire of choice. It is narrow enough that U can still get the full suspension travel and tall enough to provide good traction. With the larger tires I had to have rubber spacers in my springs to prevent the suspension travel so my fenders would not cut the tire.

If I just roll into it the car it is a dog off the line, and then as soon as boost builds I'm ice skating a little after the 60 foot. This not only results in slower 60's but slower et's as well because I have to get off the tgas to avoid hitting the wall.

I'm running a 3k stall with LU right now it was the stall reccomended for my turbo. Which is a te-62 (basically just a 3 bolt 60-1 ). With my old 9" 3500 stall non-lu unit I could make alot more boost off the line (like 15+ lbs). Now I'm down to about a 3-4 psi launch at max. But I just anilate the tires at that boost. I've been having the best luck launching at around 1lb of boost. Rpm's around 2200...

I am running a spring loaded gainger valve for my boost control. This holds the WG closed until my desired 25lbs of boost is reached and the flings it open.I get full boost really quickly right now. This might be causeing to fast of a spool. I'll try removing that and going with a standard bleeder. I get full boost really quickly right now.

The agrivating part is all my buds with similar setups all 60 great?

So I'll eliminate the grainger valve to try and slow down the spool.
Add the camber adjusting bar.
And replace the rear struts.

Next event is in 2 weeks i'll post back and let U all know if it made a diff.

Thanks...

Id say a center section swap that actually has lower gear options:
http://www.turbobuicks.com/forums/showthread.php?t=6375

Too bad The lowest you can get for the stock pumpkin is 4.10s, meh.

Also, with a GNX motor, low gears are you friend. You've got a torque/load type motor, it doesnt need short gears and doesnt benefit from them unless youve got wrinkle walls and are running the 1/8th.

EDIT: dont do the slip yoke half shafts like he did, cos he ended up going back to T-II CV's and just modifying the stub axles in the pumpkin to fit them instead. U-bolts make you have to relocate the shocks to clear it, and that changed the suspension geometry.

And the U-bolts/slipyolks didn't work anyway.

sounds like you figured out the problem in your last post. Just hearing that i immediately thought.....ah ha! Found something! Let us know how things go cause i'd love to hear the end results.

lower gearing=numerically higher (lower top speed, but high acceleration, i see lots of guys that have drag cars have 4.56 gears, bad for highway driving, good for strips)

higher gearing=numerically lower (allows higher top speeds, but takes away acceleration)

(in response to reted) its opposite to the numbers, weird i know.

i have a 2.76 mopar 8 3/4 in my garage that high enough for you? ;)

and im going to be ditching the stock 4.10 and going with something between 3.0 and 3.73 in probably solid axle due to lack of stock gearing..

I did ok on one sec gen , 26 10.5 et's removed the sway bar to allow more transfer. and extended the body to suspension link on the diff. also i say a guy race in texas that raised the yoke side of the diff about 14 degrees and that t11 wheelied really well. I have since installed a 4 link with 9" ford and 29.5 10.5 w's. With the third gen on stock susp. and 245/40 18's i have gone 1.72 60 . Good luck.

How much Travel do you have setup on the car?
 

From my experience I would only setup about 1" of Travel if you plan on setting the car up for the 1/4 Mile. You can play with springs and coilovers but, the goal should be to minimize the amount of travel in the rear of the car to about 1". Stick the biggest slick on the wheel you can possible stuff in the wheel well. Sounds like your car is making some good torque with GN Motor in there. Look into Electronic Boost Controllers to regulate how much boost you produce so you don't blow away tire traction right off the line.

Good Luck sounds like it should be a fun ride once you get the traction stuff sorted out.

MAN I MISS BOOST!!!!

Albert

Yeah setting pinion angle can work wonders!

The link im talking about if made longer puts more pressure on the diff. when the body squatts, it also helps to keep the tires from hitting wheel wells.

Pinion angle has nothing to do with traction.

Andrew

Are you completely sure about that?? Cause i'm absolutely positive i can quote some of the biggest chassis experts in the world who will say your statement is completely false.

:rlaugh: :rlaugh: :rlaugh:

Dont claim to be expert but i think pinion angle determins the point of intersect witch helps determin body lift and the amount of lift!

Pinion angle is a factor in traction.. its not the largest factor in it but it absolutely is one... and as for the 14 deg. UP..that would do nothing but destroy u-joints and make for a bad deal.
Greg

As power is applied, the pinion will want to rotate up. If pinion movement is not contolled, than you will not be applying the all the torque to the rear end. So as a rule, in drag cars, the pinion angle is set slightly down. So under power you get optimal power transfer.

http://www.chevyhiperformance.com/te...es/index1.html

http://www.markwilliams.com/Catalog/pg70.pdf


The pinion angle has no effect on squat geometry or instant roll center.

Andrew