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4-Link Dragster Adjustments
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Author:  rick360 [ Sun Nov 07, 2010 11:06 pm ]
Post subject:  4-Link Dragster Adjustments

I've had some inconsistency due to tractions variations and am looking at ways to remedy it. Had several runs Sat that were 1.14x and then when the track started to cool (outside in 50's and sun gone from track) in Rd 3 the 60' dropped to a 1.163 and the ET off by .02+ costing me the round. The tires are huge 16-33.5-16 Hoosiers and you'd think they could pull 1.14's on oil.

I took some rough measurements of the dragster 4-link and found the IC to be 78"out and 4-7/8" up. Since the front has no suspension the % anti-squat etc can't really apply here but I assume the same basic effect from moving the IC back/up or out/down.

Since my SBC weighs quite a bit less than the BBC that was in it before and a significant change in TQ as well, what changes should I make to the bars or shocks to account for the differences?

Also thinking about moving the batteries to the rear above the rearend.

Thoughts? Opinions? Ideas? Theories? Experiences?
Rick

Author:  Slowpoke [ Mon Nov 08, 2010 7:31 am ]
Post subject:  Re: 4-Link Dragster Adjustments

I think anti-squat is still valid on a non suspended front end car, just not as sensitive as on a suspended front end. Do you have video of your launch?

Congratulations on your Personal Best \:D/

Author:  Bubstr [ Mon Nov 08, 2010 4:33 pm ]
Post subject:  Re: 4-Link Dragster Adjustments

Everything has an COG, Anti squat line and IC.

This sounds like too much hook. Dropping you on the low side of Torque curve. Cooler track adds traction. This reduces wheel speed. May be your borderline of too tall a gear or too tight of converter. A little more air pressure may tell you for sure. That would up the wheel speed and if 60s come back, BINGO. That would compensate for tight track but wouldn't take advantage of it. One of the disadvantages of less cubic inches is peakier torque curves, not as wide and flat.

This is just opinion based on wat is written.

Author:  Beretta [ Mon Nov 08, 2010 5:02 pm ]
Post subject:  Re: 4-Link Dragster Adjustments

IMO Rick, That tire is to big...

Author:  rick360 [ Mon Nov 08, 2010 8:02 pm ]
Post subject:  Re: 4-Link Dragster Adjustments

Bubstr wrote:
Everything has an COG, Anti squat line and IC.

This sounds like too much hook. Dropping you on the low side of Torque curve. Cooler track adds traction. This reduces wheel speed. May be your borderline of too tall a gear or too tight of converter. A little more air pressure may tell you for sure. That would up the wheel speed and if 60s come back, BINGO. That would compensate for tight track but wouldn't take advantage of it. One of the disadvantages of less cubic inches is peakier torque curves, not as wide and flat.

This is just opinion based on wat is written.


I agree everything has COG and IC, but I don't see how an anti-squat line can be derived w/o a front suspension. The 100% antisquat line is based on the COG and the effect acceleration thru the IC has on that COG to the front and rear suspension. When you have no front suspension I can't see how the anti-squat line is relevant.

It wasn't too much hook, it spun, by my feel and witness outside agreed. The day was cool all day but sunny making good traction all day but the track was really cooling off on that last pass. This engine has a pretty wide torque/power curve but is just much less than a 1000HP BBC.

Rick

Author:  rick360 [ Mon Nov 08, 2010 8:08 pm ]
Post subject:  Re: 4-Link Dragster Adjustments

Beretta wrote:
IMO Rick, That tire is to big...

Can you explain how/why too big will make it spin?

I've heard others comment about tires "too big" for small blocks, but don't see how MORE tire on the ground could reduce traction. I am sure it would run quicker with a smaller tire, but I want it to dead-hook and consistency is top priority, not quickest ET.

Rick

Author:  Slowpoke [ Mon Nov 08, 2010 8:28 pm ]
Post subject:  Re: 4-Link Dragster Adjustments

A video of your launch would help.

Author:  rick360 [ Mon Nov 08, 2010 9:37 pm ]
Post subject:  Re: 4-Link Dragster Adjustments

Slowpoke wrote:
A video of your launch would help.

No video of the run in question. I only have one video on computer but its from the stands and is not close enough to see the suspension or tires. Had another video on digital tape and don't have a way to get it onto the computer, ... :-k but just got a new DVR w/DVD burner that I may be able to hook the camera up to so I can dub a DVD. Will have to investigate the DVR.

Rick

Author:  randy355 [ Tue Nov 09, 2010 12:24 am ]
Post subject:  Re: 4-Link Dragster Adjustments

I'm also having trouble understanding how TOO much hook, can hurt consistency?
The no jet extention passes had the most consistent 60's. If there was a time when it had TOO much hook, that would have been it.

The car did spin on that last pass.

One thing left out here is the track personel.
In earlier rounds they were spraying the starting line. He sprayed where the rear wheels of most door slamers sit when staged. Then he was done. I asked for some spray where the rear tires of dragsters are when staged. He said I'm going to do that. He sprayed about 4' behind where the door cars rear tire sit while staged. I guess he doesn't know how long dragsters are.

The variables here seem to me that I'd error on the side of lots of traction.

Maybe tracks should have a racer to track personel IQ ratio???
Probably more important than rod to stroke ratio!!!??

Author:  ky mustang [ Wed Nov 10, 2010 10:10 am ]
Post subject:  Re: 4-Link Dragster Adjustments

not enough torque on a big tire will "wind the tire up ", but not be able to keep it "wound up" and it unwinds its self and slips instead of get up on it "recover" and stay hooked.

check out this slow mo video

http://www.youtube.com/watch?v=Mgnal7TK ... r_embedded

Author:  Ken0069 [ Wed Nov 10, 2010 11:40 am ]
Post subject:  Re: 4-Link Dragster Adjustments

randy355 wrote:
One thing left out here is the track personel. <snip> I guess he doesn't know how long dragsters are.

The variables here seem to me that I'd error on the side of lots of traction.

Maybe tracks should have a racer to track personel IQ ratio???
Probably more important than rod to stroke ratio!!!??


When it comes to racing, some can and some can't, some will and some won't, some do and some don't. Just remember that Can't, Won't and Don't are either track owners or workers and they are usually just in it for the money or a power trip! ;-)

Author:  Bubstr [ Thu Nov 11, 2010 9:02 am ]
Post subject:  Re: 4-Link Dragster Adjustments

That opinion was written on what you had put out in first post. Cool weather usually means more hook to a point. nothing was said about stupid track personal. lol What else has anything to do with this? Alky or Gas? Jettings for weather? Tire pressures and wear? Engine heat at line? Trans and rear end temps? Tire temps at line? Lots of things could change it .02.

Author:  Beretta [ Thu Nov 11, 2010 12:04 pm ]
Post subject:  Re: 4-Link Dragster Adjustments

ky mustang wrote:
not enough torque on a big tire will "wind the tire up ", but not be able to keep it "wound up" and it unwinds its self and slips instead of get up on it "recover" and stay hooked.

check out this slow mo video

http://www.youtube.com/watch?v=Mgnal7TK ... r_embedded




That is one of the best vid's I have seen!!!!!!!!Thanks Randy

Author:  rick360 [ Thu Nov 11, 2010 7:08 pm ]
Post subject:  Re: 4-Link Dragster Adjustments

That is an interesting video but I didn't see any underpowered big tire cars in that video. =;

Will a 4-link car w/o front suspension always squat or separate on launch or can the 4-link adjustment change the reaction even with no front suspension (ie front travel =zero). Does some chassis flex in the tubing "act" like front suspension? :-k The COG is back near the engine ~5' in front of rear axle. I can't really wrap my brain around how this works. ](*,) I never hear much about dragster 4-link settings as though they have very little effect on how they run.

I know in chassis cars the COG height is VERY important for weight transfer, suspension function and traction and should have the same effect in a dragster (or anything else). I have thought about raising the engine as a way of raising the COG. With a BBC in the car it accelerates faster and it has a higher COG than with the SBC in the car. Don't want to raise the COG so high that it lifts the front on launch.

Rick

Author:  ron owens [ Thu Nov 11, 2010 8:18 pm ]
Post subject:  Re: 4-Link Dragster Adjustments

A friend of mine that has two dragsters was both SBC cars he just changed one of them over to a BBC 598 cube Big chief engine he had to move his top bars up one hole it was hitting the tire's to hard and spinning of the line .

I did see the tickets before and after it had 106 60"s before the move and after it had 101 60"s so i guess it worked for him.
But i don't know much about those long car's

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