Author Topic: Considering first 1/4 mile-how to launch-what to expect  (Read 6400 times)

Offline 1980c10

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Considering first 1/4 mile-how to launch-what to expect
« on: September 20, 2011, 12:19:08 AM »
I would like to (maybe) run my truck at the local 1/4 mile track.
Mostly I am curious as to how fast it can run.
I have never drag raced legally, so I have a few questions, looking for some pointers and tips as well.
So about my truck;
'80 1/2 ton swb 2wd
393 hp 432 ft lbs  350
5 speed manual transmission nv 3500
10 bolt-dont know the gearing but goes down the interstate quietly with OD.
275/60/15 firestone firehawk tires
I have softened up the suspension in the rear(removed some leafs) and stiffened it in the front(lowering springs), so the truck squats and stays squated as long as I am on the throttle This seems to help with traction a ton. It will spin but grab and go at the same time.
my thought so far;
To prep the truck I will remove un-needed items.
Maybe run 1/4 tank of gas
air front tires to max psi rear to just below 30
Anyway I really dont want to break anything but also want a good launch
so how do I launch this truck off the line?
How hard do I grab 2nd gear. On the street I have to be careful to not spin out.
Bear in mind I shift to 2nd around 28mph with this trans
How much more grip will I get at the track vs the street?



Offline Irish_Alley

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Re: Considering first 1/4 mile-how to launch-what to expect
« Reply #1 on: September 20, 2011, 12:46:42 AM »
can a nv3500 and 10 bolt hold up to almost 400 hp?
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Offline zieg85

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Re: Considering first 1/4 mile-how to launch-what to expect
« Reply #2 on: September 20, 2011, 06:07:38 AM »
I'd be careful, you can make that 5 speed junk in a hurry if you abuse it.
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Offline 1980c10

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Re: Considering first 1/4 mile-how to launch-what to expect
« Reply #3 on: September 20, 2011, 08:14:40 PM »
I've launced it pretty hard but not all out a few times but I would think a dragstrip would be a lot stickier which makes me a little nervous but I will still baby it a little off the line and when shifting gears. I don't plan on racing this on a regular basis but its definatley quick and I am curious as to what times I can run. I would not run any more tire than what I have on it now as well.

Offline 1979C20

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Re: Considering first 1/4 mile-how to launch-what to expect
« Reply #4 on: September 20, 2011, 08:25:21 PM »
I would run 10 pounds of air for more grip on the track. Start in second, get the RPMs up around 2500 or 3k and dump the clutch. I say start in second since its a 5 speed and first gear might be too low and too short. About a second after the last yellow light comes on is when I dump it, the green usually flashes once you get traction. Thats just me.
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Offline VileZambonie

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Re: Considering first 1/4 mile-how to launch-what to expect
« Reply #5 on: September 20, 2011, 10:29:53 PM »
You really should know your final drive ratio and really don't sound like you're set up for a day at the drags.
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Offline Irish_Alley

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Re: Considering first 1/4 mile-how to launch-what to expect
« Reply #6 on: September 21, 2011, 12:50:03 AM »
im with vile. its one thing to take like a stock truck and just run it. but if you have built up just one part you will find a weak link real fast. there’s a saying "fast, cheap or reliable you can only pick two" you will see not building everything up and to the right rpm well that kind of picks fast and cheap. yeah you will be fast but even on a 3/4 ton i wouldn’t dare to dump the clutch unless im in the mud due to once something catches traction it will chew the heck out of your ring and pinion with the flex it will do. Now if you were to do a rolling start it wouldn’t be so hard on parts but you cant do that at the strip. You have to watch for axle flex also
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Offline 1980c10

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Re: Considering first 1/4 mile-how to launch-what to expect
« Reply #7 on: September 21, 2011, 01:39:43 AM »
I would start in 1st as first is not a low first gear I can run up to about 28mph in first and 68 in second.
10 lbs seemsl low for tire pressure I was thinking a min. of 25psi (don't want to ruin my tires)
As far as breaking things;
I would not ever dump my clutch from a stop period. I do let it drop a little going into second but not too much so I can control tire spin
2nd to 3rd I am afraid of spinning out so I ease that one a little as well.
I am running normal street tires
so when I run from a stop light in town if I want to go fast I focus on not spinning out and not slamming my drivetrain.
I haven't gotten to my gear ratio etc as I have other things that I want to do first such as new guages etc.
I also wouldn't be racing just a test and tune night so i would play it a little on the safe side.
as far as my clutch it is a heavy duty version.
The nv3500 has a reputation for being weaker than it is IMO;
-it was put behind 350's in 1/2 tons with 4wd
-I think some of that comes from their being a heavier trans available (nv4500)
anyway mine was rebuilt/rebuilt for a street rod although I don't know all of what would have been beefed up.
-my driveshaft was built by a local guy that builds them for racers He built the same as he builds them for pulling trucks
-I am running a ten bolt so that is my weak point.
« Last Edit: September 21, 2011, 01:43:44 AM by 1980c10 »

Offline Irish_Alley

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Re: Considering first 1/4 mile-how to launch-what to expect
« Reply #8 on: September 21, 2011, 04:12:04 AM »
might be true about the nv3500 never broke one but i haven’t driven one lol. but just like my impala they made one transmission for the 3.4 and 3.8 n/a engines but the s/c 3.8 came with a stronger engine cause gm knew the weaker one would hold up. but even the one for the s/c it has a tendency to fail
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Offline Captkaos

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Re: Considering first 1/4 mile-how to launch-what to expect
« Reply #9 on: September 21, 2011, 06:12:06 PM »
The trans is still your weak point, and definitely not the 10 bolt.  The U-joints will go first IF you ever hook it up, with street tires you have nothing to worry about.  after that you are looking at the clutch if you aren't dumping it.  slipping it out under a launch is going to burn it up.

Offline 1980c10

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Re: Considering first 1/4 mile-how to launch-what to expect
« Reply #10 on: September 21, 2011, 10:39:58 PM »
Anyway I just want to run it a few times down the track for a couple of reasons
-I've never done it before
-sounds like fun.
-I want to see how quick it can run.
I don't plan on beating the poor truck to get it down the track I just want to shake it a little.
If taking it easy makes my time a little slower I can live with it.
My main goal is to have fun.


Offline Irish_Alley

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Re: Considering first 1/4 mile-how to launch-what to expect
« Reply #11 on: September 21, 2011, 10:47:05 PM »
they make a ap for that 8)
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When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline 1980c10

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Re: Considering first 1/4 mile-how to launch-what to expect
« Reply #12 on: September 21, 2011, 10:58:17 PM »
I won't buy an nv4500 as they cost a lot of money and are a truck like trans with too low of a first gear.
If it is ever in my budget a t56 could be in my future but i can go through a few nv3500's for the same price.
nv 3500 is stronger than a t5 and have seen plenty of mustangs beat the poor t5's on several ocassions without a lot of failure.
So i feel relativley safe. plus the feel and gearing of the nv 3500 feels great.


kind of off subject but I did blow up the nv4500 in the work truck today.

Irish, if i could just get a deer to run across the screen on my phone I'll be set :D.

Offline Captkaos

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Re: Considering first 1/4 mile-how to launch-what to expect
« Reply #13 on: September 22, 2011, 09:47:21 AM »
If you are running street tires and you don't plan to do this 100's of times every weekend, eventually you will start finding you week points.  If the trans is a new rebuild and you just want to run it down the track, I wouldn't be scared about.  If you are running slicks...  Another story.

Offline 1980c10

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Re: Considering first 1/4 mile-how to launch-what to expect
« Reply #14 on: September 22, 2011, 08:43:19 PM »
Really I just want to see the numbers and experience the 1/4 mile. I wouldn't use the 5 speed for regular drag racing. If I do break something; It might just mean it was close to breaking anyway.

I wouldn't really let the clutch slip very much. I would just try to find a happy medium between not dumping it and getting into the throttle it would probably be just more of a slow release(find the friction point and then let it go).