4 link adjustment on drag radial

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soslojoe1970
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4 link adjustment on drag radial

#1 Post by soslojoe1970 » Wed Apr 08, 2009 8:16 am

OK i have a 70 nova with 4 link rear suspension. I run a 31-10.5-15 MT slick most of the time. It 60 foots 1.33 on motor and 1.20 on the spray, with 0 problems hooking. NOW I am trying the 315-60-15 MT drag radial for a new class Im trying to race. I do my burnout and pull up to the line and once I release the trans brake the car blows the tires off. I tried 13psi - 16psi with the same result. The last pass I tried doing a couple dry hops in the burnout area and it hooked hard and lifted both the front tires off the ground. I went to the line and set the brake and it blow the tires off again. It doesn't even try to lift the front end up, before blowing off the tires. I am only leaving on motor no spray. Any ideas?

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Re: 4 link adjustment on drag radial

#2 Post by John_Heard » Wed Apr 08, 2009 8:42 am

Since I've never ran radials, this is only observations on what I see those that do. You have to dead hook a radial, their stiff sidewall will not tolerate the same power/violence as a slick... you'll have to ease into it. If you're launching on motor and it's blowing them off at the hit then you'll have to take power out (Timing retard and ramp it back in) or make some suspension / chassis adjustments to see if you can get it to take it.

Air pressure, shock settings, weight (radial guys tend to run a lot of rear %), 4-link adjustments, etc.

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Re: 4 link adjustment on drag radial

#3 Post by soslojoe1970 » Wed Apr 08, 2009 8:51 am

Now yesterday I measured my ic and found by changing the back tires from the 31's to the 315 it shortened up my IC by 4 inches and raised it by 1.5 inches. Does that hit the tires harder?

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Re: 4 link adjustment on drag radial

#4 Post by John_Heard » Wed Apr 08, 2009 9:03 am

Shortening the IC and raising it should initially strike the tire harder, BUT the tire change also lowered the car I assume, which will reduce how hard it strikes the tire at the same time.

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Re: 4 link adjustment on drag radial

#5 Post by ytnova » Wed Apr 08, 2009 9:22 am

Trial and error, I would leave the 4 link alone and go after some shock adjustments first. I am assuming you have double adjustables, so write down what it likes with slicks for reference and then loosen the rebound first and hit the tire harder, like john says, it has to hook initially or they will never work. Any chance you have vidioed the car leaving on the radials? Post that up so we can see what the car is doing. As for air pressure start around 15-16 psi.
I am not really sure what the question is, but I am pretty sure the answer is Big Block.

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Re: 4 link adjustment on drag radial

#6 Post by soslojoe1970 » Wed Apr 08, 2009 9:28 am

It does have double adjustable shocks on rear. It is set pretty soft. I did try to make a couple adjustment on those as well. When I say it blew the tires off, I didn't even move. The front end didn't raise up at all. I was like sitting in the water box. Now I can do a dry hop in the burnout lane and it will yanks the tires off the ground.

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Re: 4 link adjustment on drag radial

#7 Post by John_Heard » Wed Apr 08, 2009 10:13 am

What is the difference between your dry hop and regular launch? Trans brake vs No Trans Brake? RPM? I assume you're just sticking your foot in it for a dry hop right? You're giving the tire a chance to bite that way before applying power which is probably what you're gonna need to do on the starting line. There are really a lot of ways to approach this...

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Re: 4 link adjustment on drag radial

#8 Post by soslojoe1970 » Wed Apr 08, 2009 10:30 am

That is what im doing, puting my foot into it on the dry hop. Can't I control the amount of hit with the 4 link bars to softing up the hit of the tires. Lower and extend the IC. Also how much lower and how much forward should I go. It is at 44.5 and 9.5 right now with the radials. It was 48.5 and 8 with the 31 slicks.

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DL
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Re: 4 link adjustment on drag radial

#9 Post by DL » Wed Apr 08, 2009 5:43 pm

what size of rim r u using!!!
real-street fan

soslojoe1970
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Re: 4 link adjustment on drag radial

#10 Post by soslojoe1970 » Wed Apr 08, 2009 8:47 pm

12.... several cars in our area running same size with the same weight car with 1.20 60 foot times and carring the tires 50 feet down track.

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Re: 4 link adjustment on drag radial

#11 Post by JeffMcKC » Thu Apr 09, 2009 9:56 pm

John is right a Drag Radial does not like to be shocked, dead hook also if they spin they will go into shake this breaks things, as rules of thumb, start with a lot of front tire drop, easy on extension on the rear hard on comp, 16-18 lbs in those tires. Its a very small window to hit, converters and set up have to be made for them or just be lucky. If the front did not raise then its to stiff most guys starting will top the front out then spin, pulling them on your dry hop which you should not do one of or over heat them means you have a low travel stiff ront start there first, the front end is more than the back end in these cars.
2007 HotRod's Drag Week 2007 SB/NA Champ
9.95@134, 1.30 60' Stock Susp. Drag Radials
5 Days 5 Tracks make one Weak

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Re: 4 link adjustment on drag radial

#12 Post by soslojoe1970 » Fri Apr 10, 2009 5:59 am

I was also told my IC was way to high and way to short for a drag radial. I was told the shorter and higher your IC is the harder the power hits the tires.

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Re: 4 link adjustment on drag radial

#13 Post by John_Heard » Fri Apr 10, 2009 6:51 am

soslojoe1970 wrote:I was also told my IC was way to high and way to short for a drag radial. I was told the shorter and higher your IC is the harder the power hits the tires.
All you can do is test moving it out and down and see if it likes it. However, what you're going to be doing is taking away initial hit to the tire, which is also where the car is spinning right now from what you've described. That might make the problem worse. It really sounds to me like the issue is power management.

Do you have anything to control the engine (retard curves)? Are you spraying it? When do you turn the juice on?

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Re: 4 link adjustment on drag radial

#14 Post by soslojoe1970 » Fri Apr 10, 2009 7:14 am

Im just trying to leave on motor FOR NOW.... 1.33 60foot times. I was told where I have my IC is slamming the tire to hard, and moving it forward and lower will soften it up on the initial hit. I was told reason I never had a hooking problem before is that the 31-10.5w will hook just about anything.

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Re: 4 link adjustment on drag radial

#15 Post by John_Heard » Fri Apr 10, 2009 8:29 am

If you're blowing the tires off how are you getting 1.33 60' ? Did you loosen the front end up and/or more travel?

Video would help..

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