Traction problem

Hey guys, looking for ways to improve the traction on my '86 shortbed GMC pickup. Stock suspension, 400 rwhp, beefed up 350 transmission, probably 3.08:1 rear gear. I don't plan on racing this truck just would like to be able to accelerate away from a stop light without breaking loose the rear wheel. A posi unit is definitely in my future. If I move the leaf springs mounts to the bottom of the axel housings instead of the stock positions on top will this help transfer the weight?
Thanks for any information.

Moving the springs to the bottom would definitely help,lower center of gravity. Also you could use some "slapper" bars also to control axle wrap and wheel hop.

Bigger tires or lighter foot :LOL:

I have found with my monte that when it had standard shocks on the rear i would break traction alot. But when I put on 90 lb. air shocks I have to really get into it for it to do it.

Lose the 308's also

now that i have dealt with a high tourqe light car a posi rear and big sticky tires will make as much difference as anything. if your breaking loose just tooling around ,traction bars may not help without the ehlp of the tires and both axles spinning

A front-motor rear-drive vehicle will twist the frame in such a manner that the left front and right rear get light on acceleration. The right front and the left rear get heavy. In the past, I have had good luck with using an air shock on the right rear only and adjusting pressure to the point where I get two equal black marks on the pavement. Of course, this is only a down and dirty fix until you get some suspension improvements, posi, tires and so forth.

Moving the axle to the top of the springs will also lower the back end about 5"....gonna look a bit weird unless you lower the front too..... How wide of a wheel and what tires are you running on the rear now??? What shocks do you have on the truck???

Don't know how much money you want to spend, but a posi, housing floaters, 32" ladder bars, good shocks, and soft compound tires work quite well on a pickup...

I had the same problem with my Jeep pickup that I swapped the 5.0 Mustang into.......I could smoke the tires all too easily and had to feather it off the line. If I had been serious about getting it to launch I would have gone to a posi and some stickier tires, but it was my shop truck, so I just lived with it.

If you look at any of the drag trucks running around you will see big meats under the back.

Don

Hey guys, sorry for not getting back until now. Rear tires are 30.5x9.5xr15 on 8" wheels. The front has been lowered 3" the rear 5". Tires are only about 1000 miles old with a normal street tread. Located today an entire 12 bolt assembly with new drums, shoes, and posi unit. Hopefully the measurements are the same.
Thanks again for all your input.

I would still put the rear leafs below the rear end, with good shocks. Also those adjustable "Slapper" bars.

Hey BigTruck, when you say good shocks what do you mean? And are slapper bars the right name? Are they vehicle specific or one size fits all.

Sorry , I could not remember the name same thing though. Some thing like this http://store.summitracing.com/partde...5&autoview=sku and this http://store.summitracing.com/partde...5&autoview=sku The shocks will help you transfer the weight over the rear tires better and the bars will help keep the axle from wanting to spin and cause wheel hop/poor traction. You can get creative and find other ways of getting better traction but you get the idea. They make all kind of helper springs and helper bags that you can attach.

Hey BigTruck, ok we just called them traction bars. Never knew if they helped or not. It's worth a try. Thanks

i would also like some input on the subject, i have the same problem different truck. i have a 1960 short bed with trailing arms and coil suspension. i don't yet have a posi, put off due to rod knock, but i cannot hook up for the life of me. any ideas for my suspension setup?

also i was confused at techinspectors comment about on-launch weight distribution. when i do burnouts i always see my right rear tire marks, not left. is that because of my suspension. also i talked to a guy with a pro street camaro and he said i should try to put a fuel cell, pump, and all i can over the right rear tire to help improve traction, with or without a posi. i am so confused.:confused:

You can install the tank in between the rear frame rails, it will help , but you definitely need a "Posi". You can get your non "Posi" unit to "lock up" for one launch but you need to reverse a good 20-30 feet put it in first gear and hit it . It should lock up both tires. You can fit a 10" wide tire on the rear. Is it the stock suspension? Meaning is it stock height. The trailing arms in these trucks are nice when they are set up right.

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Originally Posted by Rgtrough

Hey BigTruck, ok we just called them traction bars. Never knew if they helped or not. It's worth a try. Thanks

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You can also use these http://www.jcwhitney.com/autoparts/P...=group_listing And yes they are worth it and work, espcially with a Posi track.

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Originally Posted by les4metal

i would also like some input on the subject, i have the same problem different truck. i have a 1960 short bed with trailing arms and coil suspension. i don't yet have a posi, put off due to rod knock, but i cannot hook up for the life of me. any ideas for my suspension setup?

also i was confused at techinspectors comment about on-launch weight distribution. when i do burnouts i always see my right rear tire marks, not left. is that because of my suspension. also i talked to a guy with a pro street camaro and he said i should try to put a fuel cell, pump, and all i can over the right rear tire to help improve traction, with or without a posi. i am so confused.:confused:

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If you'll go back and read my reply once again, you'll see that I said the right rear gets light. The lightest tire is the one that smokes. The left rear gets heavy (has more weight on it from the chassis twist) and so does not slip. It grips and leaves no mark on the pavement.

Just a reminder, if your axle is not hopping up and down from the springs bowing up and un-bowing, a traction bar is unlikely to help much. They are designed to prevent spring wind-up from the pinion trying to climb the ring gear.

Put an air shock on the right rear only to make that tire heavier on the pavement and see what happens.

Even I have the same problem with my truck.

ok thanks guys. so the posi for sure? and about the air shocks, i've always heard of those being bad for drag racing, because they put more pressure, they lessen the weight transfer....shouldn't the rear suspension be softer? how do i properly set up the trailing arm suspension? what all is there to do?
right now it is stock height with cheapy spring clamps to drop it about an inch. i have the original springs and kyb shocks. i was considering going to the AGX adjustable shocks or a coil over all together. but now with air shocks back in the picture, what would be the best choice for my little amount of dollar?
also, what about front suspension? it came factory with coil overs and i can get some QA1 or strange shocks for a pretty good price. which is more important, front or rear suspension??????

oh and i don't have ANY sign of wheel hop at all.....i don't think i get enough traction now to even get that much out of it.

Here's a link for you. Lots of really great information to go through.

Hard to get the trailing arm suspension to hook up... just not much to work with or adjust and the arms are too long to get them to weight transfer much.... A pair of 50/50 drag shocks on the rear and 90/10's on the front will help some, but big problem with a pickup is there is so little rear weight and the front weight is so far forward it's hard to get it to transfer. A posi will at least get power applied to both wheels. Moving the fuel tank and battery as far back as possible will help a bit. The lack of weight transfer can be cured, but the process is neither cheap or easy.....

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Originally Posted by les4metal

ok thanks guys. so the posi for sure? and about the air shocks, i've always heard of those being bad for drag racing, because they put more pressure, they lessen the weight transfer....shouldn't the rear suspension be softer? how do i properly set up the trailing arm suspension? what all is there to do?
right now it is stock height with cheapy spring clamps to drop it about an inch. i have the original springs and kyb shocks. i was considering going to the AGX adjustable shocks or a coil over all together. but now with air shocks back in the picture, what would be the best choice for my little amount of dollar?
also, what about front suspension? it came factory with coil overs and i can get some QA1 or strange shocks for a pretty good price. which is more important, front or rear suspension??????

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I'll give you one thing for sure. You sure are hard-headed.
For the third time......install an air shock on the right rear only and see what happens. Pirate a shock out of the boneyard and make it work if you're short the green to buy a new one.

Seems like your making it a bit harder than it is... Get wider/better tires, flip the rear leafs under the axle and throw the air shock on the rear. It's cheaper, will hook up, etc. No point in buying posi unit, high end suspension, etc for a street truck. I had the same truck but a long bed and I know that it didn't hook up worth crap. Wider and better tires helped but still wasn't great but again, it was a street truck daily driver. I just got used to getting a roll first and slowly put my foot into the throttle and going, especially in the rain. You said you want to do this cheap so the air shock is the way to go. If not then look into Cal Tracks (maybe wrong on spelling) and wider/stickier tires and a posi rear unit.

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Originally Posted by techinspector1

I'll give you one thing for sure. You sure are hard-headed.
For the third time......install an air shock on the right rear only and see what happens. Pirate a shock out of the boneyard and make it work if you're short the green to buy a new one.

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What Richard is talking about is anti-squat....he's trying to head you in the direction of the right tire lifting into the suspension of your truck, therefore lightening or " lifting" that tire.
You definitely need a posi and some more geometry work, but that air shock idea gives you a base point to start because it will show you tire plant and squat for a start.

awesome thank you guys so much for all your help. sorry tech, i don't mean to be hard headed i just like to be able to understand new things a little more in depth. so an air shock and posi are in store. and tires......i have a set of 275 Dunlops on it right now. and i heard anything like a drag radial gets hard during normal street driving and weather???? the only reason i was even considering a coil over set up for the rear is because i can get comp engineering set up for about $150, and if it was worth it i'd only have to do it once and i'd be set for ever. i don't plan on getting rid of this truck any time soon it was my first and i'm hoping to have it really nice for my kid. plus i really like have the factory coil overs up front....i have some QA1s up there and like them. plus the fact that they are rebuildable is nice too.
this truck is my daily driver, but i live about 2 miles from work.......and all i care about right now is making this a real badass daily. thanks for all your guys' help, really i appreciate it.

now for a posi unit, does anyone have any experience with POWERTRAX? i was thinking of doing that so i don't have to change my gears or carrier. my friend just got one a few months ago and it seems to be fine.....but he hasn't improved his 60 foots at all.....he has a 69 firebird. it's not as loud as i expected, because of what everyone says...i could live with it.......but how reliable are they? how much power can they take? they are less than half the cost of a full posi unit, i like that part :)

oh and air shock in right rear means passenger side right?

thanks again

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Originally Posted by les4metal

oh and air shock in right rear means passenger side right?

thanks again

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yes, passenger side.