Traction problems?

[Ted Brown]

Just a quick thought from and old guy... Have someone Watch your T or car when you step on the gas pedal, when the car first moves at all, does it go up? or down? This will explain all about instant traction in a nutshell...
If it moves down, you are slow coming out of the gate and probably will get tire spin... Why? This setup requires the chassis to squat on the springs... With a lift (goes up) suspension, the bars have to lift the chassis (no springs required at that time) this puts all that lifted weight totally onto the tires and track surface... SO; Make the bars the correct length so as to be picking up the MOST weight without tipping the car over backwards... end of story PS, I heard a fellow tell someone that a Panhard bar allows a rear or front end to move in a side ways motion when the chassis moves up or down, it forces this movement, whether you want it or not, so make your Panhard bar as long as possible when using one...

 

[RPM]

Using a 4 link, (not a 4 bar) and finding the instant center of the car will fix all that. Links 10" to 15" will work in a T Bucket.

 

[Ted Brown]

Well let me tell you about my racing those type LINKs on any other chassis, they were hide burners compared to mine, no race at all from a dead stop... many, many times I have proved this out, both on the track and street. on both Pro cars and supercharged AG/Super cars... A 4 link setup will allow more chassis twist without changing tire traction, but "pro" racing track tires now days make all the difference... this is what makes the World go round...

 

[Ted Brown]

But remember this, does it go up? or down?? that is the answer, no matter what type you run...

 

[deckofficer]

Ted,

My days of gooseing it in 1st gear are over with the new engine. It does maintain traction and for that reason I won't romp 1st gear because I want that Jag rear end to live. Correct me if I'm wrong, but a Jag sedan might produce 350 lb/ft of torque through a 1st gear of about 3.0 to 1. That means the rear end should be designed to tolerate at least 1050 lb/ft of torque. With my new 383 producing over 500 lb/ft then the rear end sees over 1500 lb/ft. 2nd gear however is 2.0 to 1, so I feel safe that the rear end could handle full throttle in 2nd gear. Ted, is my math and assumptions correct?

Bob

 

[old round fart]

When thinking about rear end destruction, don't forget the difference in weight between the Jag and your Track T. I think the T will move before it tears up the rear end!

 

[guilld]

Using a 4 link, (not a 4 bar) and finding the instant center of the car will fix all that. Links 10" to 15" will work in a T Bucket.

What is the difference between 4 bar and 4 link?

 

[Lee_in_KC]

When I was contemplating putting the Jag in my 500+ hp T, I asked about it over on Hotrodders.com, where there are some very knowledgeable folks. General consensus was that the Jag, which is essentially a Dana 44, would be good for at least 500 hp/500 ft/lbs of torque. One guy said he was running 700+ hp through his in a drag car with no issues. The weak points in the Jag are the U-joints and the half-shafts. I'm running heavy-duty U-joints in mine, but still have the stock half-shafts. There are after-market half-shafts that are supposedly good for 800+ hp.

 

[EX JUNK]

What is the difference between 4 bar and 4 link?

One difference is that in a 4 "bar" the upper and lower bar must be parallel to each other whereas in a 4 "link" they are not.

This is a 4 "bar".

This is a 4 "link". Notice that they are adjustable for the best traction upon acceleration.

I hope that this clears things up for you.

Jim

 

[RPM]

What is the difference between 4 bar and 4 link?

A 4 link the bars form a cut off triangle. Buy adjusting these bars you can change everything about how the car hooks up. All the Pro Stock and Pro Mod cars use this type suspension. If it wants to steer left or right these can be adjusted to correct all that. You want to adjust these to the intsant center of the cars weight. When you get it right these want to pick up the whole car and the rotation of the rear end put all of the cars weight on the rear tires. That is over simplified, but I got to get back to work.

With the 4 bar that is used in street rods most of the time the bars are parallel and are not adjustable, on for length.

This was my in laws car from back 1990. It ran 7.0 at 200 mph and it used the 4 link.
A Gene Fulton 577 Rodeck engine with 3 stages of N20.
Mike will remember this car very well.

 

[deckofficer]

ORF,

Your correct that the mass (or lack of) that I'm trying to move is much less than a Jag sedan. I hook up very well, and considering a good romp on the Jag sedan in 1st gear would probably break the stock issue tires loose, even though I'm much lighter I would think my rear end would see more torque than the heavy Jag spinning a tire. What do you think on this subject? In my experiance, the loss of traction is a real componet saver, it is when you start getting things dialed in and are able to plant your tires that things start breaking.

Bob

 

[Keeper]

I always thought those 4 bar linkends had to be supported on both sides. Did not know you could run them only supported on the one side. I might have to reconsider using the heims and grab some of the linkends.

 

[Ted Brown]

Whenever using a single type bar or link, Heim joints are fine, as there is no side pressure on them, as long as the ends are 90 degrees to each other... Plus a 4 bar does not need to be square, you can run the frame ends close to each other for extra clearance if you like, they still work great, as long as they are not too short, in all reality the longer the better... less for and aft movement with longer bars, but they need to be a bigger diameter and maybe even a heaver wall, .156 at the least and more, the stronger the better... Plus they work best mounted to the center of the rotation point (center of ft. spindle or rear axle) and look at the cars when they leave the line, with the new gripper tires, you need no suspension at all except to adjust the rear steering effect that the offset traction causes... Look at that cars chassis leaving the line, it is squatting.. Now if they were a street car with street tires, they would be smoking with any HP to speak of... If that 4 LINK lifts, where is the lift??? none there, a 4 link will pick up nothing, even a dragster chassis with out any rear suspension will do a wheelie with the right tires...

 

[Mike]

If that 4 LINK lifts, where is the lift??? none there, a 4 link will pick up nothing, even a dragster chassis with out any rear suspension will do a wheelie with the right tires...

Ted, body separation isn't necessary to plant the tire. A triangulated four link can give you all the benefits of a ladder bar setup that is also infinitely adjustable for theoretical length. With a ladder bar, you have a bar of a pre-determined length that you mount to the car. With a four link and an understanding of the car's center of gravity, instant center (defined as the static IC) and the anti-squat line, you can adjust the suspension for specific track conditions.

When it comes to chassis sophistication, I feel the Pro Stock cars are at the top of the heap. Check this video out and watch for any signs of body separation.

[media]

The very first car in the video is driven by a fellow for whom I have tremendous respect. When it comes to clutch and chassis tuning, I think Mike is one of the best guys out there. And if you were able to see the car from the other side, you would notice the rear of the rocker panel brushing the track as the car leaves. The exact opposite of body separation. That is how hard these cars can stick the tires. I'm not going to say too much here, but notice how much attention is given to the adjustment of the wheelie bars? Do you really think a .125" of bar height means diddley-squat to how high the front end of the car might come up? I'll give you some food for thought, by leaving it at that. At 2350 lbs., these 500 CID cars are still covering the initial 60 feet of the track in the .984 second range, so it's pretty tough to say a four link can't work.

Here is a shot to show you the bar on the rear of the car -

And here are two images to show you how the track conditions can determine the height of the bar -

At the initial hit, everything is looking pretty good.

But now look at what is happening. The car is sticking the tire too hard, it has sucked the chassis down and Brian is about to have an Excedrin moment as the tires are getting ready to shake. For those conditions and the amount of clutch in the car, the bar was set too high. The car has actually stuck the tire too hard, but the car is getting sucked down to the track, rather than exhibiting any kind of chassis lift.

Now look at the car in this one -

Notice the front end is up a good amount, but the real story is being told by the rear tire and that track behind the car. I don't need to see the time slip to know the car was on a very good pass. When the car would leave like that and just quiver the tops of the tires as it went into 3rd gear, I knew we were going to be a top 4 qualifier, every time.

Special thanks to Dave Kommel at Auto Imagery for the great shots of the car. Dave, you're still the best!

@Ron - Wow, that picture is an oldie but goodie. I need to scan some older shots of the dragster.

 

[Ted Brown]

Mike, I will agree with what you say, but you are talking about tires that are totally different than any type of street tires... Those new tires are without a doubt VERY trick, they grip with super holding power, much unlike any street tire... any time a body spends going down is still wasted time... holding all or 95% of the total cars weight up with the rear end's torque arm, would most likely put too much traction to all those super high HP cars, besides like I have been saying, the pro track stuff is totally different from a street drivin car... Torque arms on the late Chevy cars are are still the quickest, they lift the total chassis, which plants the tires very hard instantly... We car agree to disagree on these two different traction ideas, but remember this one fact, the street and track and pro sticky tires are two very different horse's... right?

 

[RPM]

Mike, I will agree with what you say, but you are talking about tires that are totally different than any type of street tires... Those new tires are without a doubt VERY trick, they grip with super holding power, much unlike any street tire... any time a body spends going down is still wasted time... holding all or 95% of the total cars weight up with the rear end's torque arm, would most likely put too much traction to all those super high HP cars, besides like I have been saying, the pro track stuff is totally different from a street drivin car... Torque arms on the late Chevy cars are are still the quickest, they lift the total chassis, which plants the tires very hard instantly... We car agree to disagree on these two different traction ideas, but remember this one fact, the street and track and pro sticky tires are two very different horse's... right?

No Ted we don't agree. they make some street legal drag slicks.. That will hook as good as the pro tires. Check this out from Jegs.

Street legal drag slicks.

They ain't worth a flip in the rain, but we are talking a hole shot in a street car.

I don't run street legal DOT tires on the back of my T anyway. Firestone dirt track tires 32" tall and 20" wide. With 40" of rubber, posi rear, a soft compound and a drag race 4 link, it will hook.

 

[Ted Brown]

Good for you, I like my tires to be legal, too many dippy new officers that like to enforce the letter of the law when it comes to safety, tires, lights, brakes, etc. etc. I used to love running guys like you, did not bother me one bit. End of head banging...

 

[Keeper]

It just baffles me how much knowledge is on this board!

When did they switch the headers to well, headers instead of just straight pipes? I always thought they used the down force of the exhaust for traction purposes (yeah I am showing my ignorance)

 

[Northstar T]

ya and there's only three on each side. where does the other one go? :jester:

different classes use different methods I recon.

Russ

 

[RPM]

ya and there's only three on each side. where does the other one go? :jester:

different classes use different methods I recon.

Russ

I believe it is a V-6 so only 3 pipes per side.