Jamesd Duff Bars aint Chit!!!!
this is the Ultimate in wheel hop control!!!!!!!!!!
this is the Ultimate in wheel hop control!!!!!!!!!!
traction bars 101
- Thread starter Spencedaddy
- Start date
lobo1117
ThunderBolt SVT 94 Bronco
Jamesd Duff Bars aint Chit!!!!
this is the Ultimate in wheel hop control!!!!!!!!!!
Yeah but they cost over $99 a pair.. :sigh:
lightningDan
just saving the world....
Jamesd Duff Bars aint Chit!!!!
this is the Ultimate in wheel hop control!!!!!!!!!!
bobby is this the quad shocks they used back in the day?
SactoLightning
Kenne Bell First Gen
Hahaha sticky!!!
Jamie V
Well-known member
Yup! the shock moving allows the leafs to move up/down and front/back without binding them up! I believe Ralph use to run them on his white truck that ran 11's back in the day!
SwithStang
Member
Sorry, but I gotta jump in too....I'm on a stock motor, was initially thinking long bars, then was sold on the Duff bars by our two sales reps...then Jamie had me thinking the long bars would be more comfortable for my daily driver....also, I'm staying stock suspension but have also wanted to run Sulastic rear shackles for more comfort.
Has anyone used sulastics WITH long bars or any other hop-stopper? Thanks.
Has anyone used sulastics WITH long bars or any other hop-stopper? Thanks.
Jamie V
Well-known member
I've never heard or met anyone with them before.
What part of your ride are you trying to get more comfort from? Is the rearend too stiff for you? If you don't do any towing you could remove a leaf or two from your spring pack to soften up the ride. It's wayy cheaper then those shackles and if you don't like it you can just add them back.
What part of your ride are you trying to get more comfort from? Is the rearend too stiff for you? If you don't do any towing you could remove a leaf or two from your spring pack to soften up the ride. It's wayy cheaper then those shackles and if you don't like it you can just add them back.
Lucifer Sam 2
50 shades of gray
its the same concept that the 99-04 mustang GTs come with
SwithStang
Member
Yeah, the rear is too stiff. Fun on smooth highways and entrance ramps, but since I do 90% of my driving on Chicago city streets with cracks, buckles and holes, it is messing with my lower back. Recently I made my first trip to the strip and shimmed up the snubbers, using longer bolts. Lost one of the old short bolts, so I'm still shimmed up during daily driving.
So....maybe lose the slappers and one leaf from the bottom and put the Johnny bars on it? I never tow and bed cargo is usually a gallon of milk and some bread.
Super Cab L
I've Fallen&Can't Get Up
I run the Sulastic's and Cal-tracs. I've had them on for about 12 yrs. I decided to go with Cal-tracs after Mike Arnett the founder of Silverstate Motorsports told me about taking the local autocross championship 2 yrs in a row with the Cal-tracs on his turbo Gen I. Mine are not noisy and I don't have clearance issues like some do with long bars. So far I'm only running a little over 300HP to the tires and have had no problems.
Roy
SwithStang
Member
Thanks for the feedback.
max for the 8.8 as a whole? or the Limited slip?
i'm not cutting anything that good, and have a mac girdle on it... just curious if i should worry...
Jamie V
Well-known member
needmorepower
No, seriously.
What I mean is that 1.7 60' times are the fastest you can go on the stock slapper bars with the snubbers shimmed, because at that point, axle hop comes back.
I have an Eaton Posi in mine, no girdle at the time, not that it would have made a difference. I split one of the spider gears in half and it proceeded to take out everything else. $1,000 in parts later...
The 8.8 is plenty strong, judging by how fast guys on here are going with them, so no need to worry about your diff. unless you have axle hop, which is where aftermarket traction bars come into the picture.
blownragtop
Member
I’m somewhat hesitant to post this. I am not a suspension expert – in fact it’s probably the area of automotives that I know the least about. And this forum, more than most, seems to be poorly receptive to thoughts that run contrary to convention. Oh well, at the risk of being called stupid – let’s stir the pot. :stirpot:
Jamie has (unwittingly) done a good job of running down some of the negatives of long bars – but I’ll summarize:
1. No adjustability
2. Bind
3. Poor geometry
The first two are obvious and easily understood. The third you could write a book about. In fact this guy did.
^one of my reference books^
I’m going to try to explain it as briefly as possible to the best of my understanding. I’m also going to showcase my photoshop skills with some very poorly rendered graphics. Enjoy.
(Disclaimer; the pictures are not intended to be accurate – they are for illustrative purposes only. Please don’t PM me with death threats and comments about my mother because my CG is misplaced.)
Let’s start with instant center. The instant center is the point about which the rear end pivots as it moves up and down with the suspension. The instant center is easy to see on a ladder bar car – it’s the point where the bars attach to the frame (crossmember). On a four link car it’s the imaginary point where the bars would intersect. When you add a traction device, like a long bar or Caltrac, you have effectively created a four link with the leaf spring acting as the upper link, In the pictures below I have marked the instant centers with a yellow ‘X’. If you draw a diagonal line from the contact patch of the rear wheels through the instant center you get the ‘line of force’ or 'force vector' through which the forward momentum from the tires is conveyed to the vehicle. (The purple lines in the pictures below.)
Now let’s turn our attention to squat. First let’s draw a vertical line through the center of the front wheels, then draw a perpendicular line that runs through the vehicle’s center of gravity (estimated in the pictures as roughly camshaft high and somewhere forward of center on our slightly nose heavy Lightning). Now from that point of intersection we draw a diagonal line to the contact patch of the rear tire. This line is the “100% anti-squat” line. (The white diagonal line in the pictures.)
What is anti-squat and why is it important? Anti-squat is a by-product of the geometry of the rear suspension where the axle is ‘pushed’ away from the body of the car (by the lower link) under acceleration (this is called ‘separation’). This ‘plants’ the tires and increases traction. Conversely, squat is the upward movement of the rear suspension under acceleration which unloads the rear tires – thereby decreasing traction. It’s easy to mistake squat as effective weight transfer. It is not.
Long bars
Caltracs
As you can see from the pictures the geometry of the long bar promotes squat (line of force is below the 100% anti-squat line) – Caltracs promote anti-squat (line of force is above the 100% anti-squat line). What this means from a practical perspective is that you can hit the tires harder with Caltracs than you ever could with long bars.
In summary – long bars are an idiot proof way to eliminate wheel hop. If you’re serious about racing they are not the best choice (they’re probably the worst) but when the differences are measured in 100ths of a second most people aren’t going to care. And since Caltracs require proper set up to be effective those same people would probably never realize their benefits.
Happy motoring… :heart:
Steve
Jamie has (unwittingly) done a good job of running down some of the negatives of long bars – but I’ll summarize:
1. No adjustability
2. Bind
3. Poor geometry
The first two are obvious and easily understood. The third you could write a book about. In fact this guy did.
^one of my reference books^
I’m going to try to explain it as briefly as possible to the best of my understanding. I’m also going to showcase my photoshop skills with some very poorly rendered graphics. Enjoy.
(Disclaimer; the pictures are not intended to be accurate – they are for illustrative purposes only. Please don’t PM me with death threats and comments about my mother because my CG is misplaced.)
Let’s start with instant center. The instant center is the point about which the rear end pivots as it moves up and down with the suspension. The instant center is easy to see on a ladder bar car – it’s the point where the bars attach to the frame (crossmember). On a four link car it’s the imaginary point where the bars would intersect. When you add a traction device, like a long bar or Caltrac, you have effectively created a four link with the leaf spring acting as the upper link, In the pictures below I have marked the instant centers with a yellow ‘X’. If you draw a diagonal line from the contact patch of the rear wheels through the instant center you get the ‘line of force’ or 'force vector' through which the forward momentum from the tires is conveyed to the vehicle. (The purple lines in the pictures below.)
Now let’s turn our attention to squat. First let’s draw a vertical line through the center of the front wheels, then draw a perpendicular line that runs through the vehicle’s center of gravity (estimated in the pictures as roughly camshaft high and somewhere forward of center on our slightly nose heavy Lightning). Now from that point of intersection we draw a diagonal line to the contact patch of the rear tire. This line is the “100% anti-squat” line. (The white diagonal line in the pictures.)
What is anti-squat and why is it important? Anti-squat is a by-product of the geometry of the rear suspension where the axle is ‘pushed’ away from the body of the car (by the lower link) under acceleration (this is called ‘separation’). This ‘plants’ the tires and increases traction. Conversely, squat is the upward movement of the rear suspension under acceleration which unloads the rear tires – thereby decreasing traction. It’s easy to mistake squat as effective weight transfer. It is not.
Long bars
Caltracs
As you can see from the pictures the geometry of the long bar promotes squat (line of force is below the 100% anti-squat line) – Caltracs promote anti-squat (line of force is above the 100% anti-squat line). What this means from a practical perspective is that you can hit the tires harder with Caltracs than you ever could with long bars.
In summary – long bars are an idiot proof way to eliminate wheel hop. If you’re serious about racing they are not the best choice (they’re probably the worst) but when the differences are measured in 100ths of a second most people aren’t going to care. And since Caltracs require proper set up to be effective those same people would probably never realize their benefits.
Happy motoring… :heart:
Steve
horsepower
Member
Very good explanation Steve. Thanks.
oops missed that, sorry ;o
IVSVS
Born Ignorant
Thanks Steve! Since anti-squat is what we are after, (This is how mopar leaf spring suspensions from the 60's are set up) and long bars are not the best pick has anyone tried a pinion snubber?
Jamie V
Well-known member
I’m somewhat hesitant to post this. I am not a suspension expert – in fact it’s probably the area of automotives that I know the least about. And this forum, more than most, seems to be poorly receptive to thoughts that run contrary to convention. Oh well, at the risk of being called stupid – let’s stir the pot. :stirpot:
Jamie has (unwittingly) done a good job of running down some of the negatives of long bars – but I’ll summarize:
1. No adjustability
2. Bind
3. Poor geometry
The first two are obvious and easily understood. The third you could write a book about. In fact this guy did.
^one of my reference books^
I’m going to try to explain it as briefly as possible to the best of my understanding. I’m also going to showcase my photoshop skills with some very poorly rendered graphics. Enjoy.
(Disclaimer; the pictures are not intended to be accurate – they are for illustrative purposes only. Please don’t PM me with death threats and comments about my mother because my CG is misplaced.)
Let’s start with instant center. The instant center is the point about which the rear end pivots as it moves up and down with the suspension. The instant center is easy to see on a ladder bar car – it’s the point where the bars attach to the frame (crossmember). On a four link car it’s the imaginary point where the bars would intersect. When you add a traction device, like a long bar or Caltrac, you have effectively created a four link with the leaf spring acting as the upper link, In the pictures below I have marked the instant centers with a yellow ‘X’. If you draw a diagonal line from the contact patch of the rear wheels through the instant center you get the ‘line of force’ or 'force vector' through which the forward momentum from the tires is conveyed to the vehicle. (The purple lines in the pictures below.)
Now let’s turn our attention to squat. First let’s draw a vertical line through the center of the front wheels, then draw a perpendicular line that runs through the vehicle’s center of gravity (estimated in the pictures as roughly camshaft high and somewhere forward of center on our slightly nose heavy Lightning). Now from that point of intersection we draw a diagonal line to the contact patch of the rear tire. This line is the “100% anti-squat” line. (The white diagonal line in the pictures.)
What is anti-squat and why is it important? Anti-squat is a by-product of the geometry of the rear suspension where the axle is ‘pushed’ away from the body of the car (by the lower link) under acceleration (this is called ‘separation’). This ‘plants’ the tires and increases traction. Conversely, squat is the upward movement of the rear suspension under acceleration which unloads the rear tires – thereby decreasing traction. It’s easy to mistake squat as effective weight transfer. It is not.
Long bars
Caltracs
As you can see from the pictures the geometry of the long bar promotes squat (line of force is below the 100% anti-squat line) – Caltracs promote anti-squat (line of force is above the 100% anti-squat line). What this means from a practical perspective is that you can hit the tires harder with Caltracs than you ever could with long bars.
In summary – long bars are an idiot proof way to eliminate wheel hop. If you’re serious about racing they are not the best choice (they’re probably the worst) but when the differences are measured in 100ths of a second most people aren’t going to care. And since Caltracs require proper set up to be effective those same people would probably never realize their benefits.
Happy motoring… :heart:
Steve
Steve, I don't have as much energy as you to type a great response. But I will say that there are "holes" in your explanation.
I ran a real suspension for years on my gen 1 (a 4 link) and any suspension besides a 4 link has "bind" so lets clear that up. Also I said that bar type suspensions have bind but what you failed to say is that the longer the bar the less bind there is ($99 bars have way more bind that long bars). Now you tried to explain "instant center" and "anti-squat" to all these guys and I think you just confused them even more. You stated that positive anti squat as the thing that will determine traction but you are wrong. Although it is a good contributer of that it is only 1/2 of the formula. The other half is the first item you talked about and that is the instant center. Now anti-squat should not be positive or negative it should be at 100%. if your vehicle is "squatting" or "separating" you are absorbing energy that should otherwise be moving you forward.
The instant center being more forward for the long bar is much more important for our trucks then the anti-squat from the caltracs. If our trucks were shorter and had less weight on the nose the caltracs would work better with no doubt. What happens with the caltracs is that they "plant" the tires when you launch but the power to weight ration of most trucks can't maintain that pressure and then the suspension unloads and you spin the tires.