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In a recent video, Don Adams, Lightning Chassis, stated that he felt a pullbar provided too much instant traction for a dlm. With that being said, I see Jerovetz has developed a special pullbar shock which they are having a lot of success with. Could that be the weaklink on past pullbar failures with a dlm?
Instead of instant traction, I'm going to call it massive, instant anti-squat. I'd argue it's not really the way to go on a modified either. Disconnecting the anti-squat geometry from the gas pedal is always a good thing from a consistency standpoint. I don't see the benefit to running a pullbar on ANY 4 link type suspension, regardless of tire size or vehicle weight. There would have to be some sort of unusual rule you were trying to overcome.Quote:
Originally Posted by ZERO25
What are the powers to be at Longhorn and Elite missing then?
I think I already said what I'm willing to say. There isn't a perfect car out there. When cars were toting the LF a mile high and winning, those cars were terribly flawed. Winning didn't prove the guys building them had a great grasp of vehicle dynamics.Quote:
Originally Posted by ZERO25
If the gas pedal has a big impact on your cars anti squat, your car is not as consistent as it can be and is very dependent on the driver to be perfect. People put pullbars on modifieds because people have always put pullbars on modifieds. Not all do it anymore, but there are still a lot of them.
It's no different than when I was told I was an idiot for advising people to not mount their brakes on their birdcages. Since Bloomquist did it successfully, it had to be a perfect setup.
Success is often achieved by talent and in spite of some part of a car's assembly. Eventually, someone who is fast enough does it the right way and the crowd follows. 99% of the people have no idea why they changed, they just do it.
Ok, let me ask another way. Don said they have tried both and always ended back on the pullbar.
He thought it the difference was in the traction difference between the mod and dlm tire. How do you respond to that?
Pretty simple. If your suspension fully extends, the "traction device" is giving you all the anti squat it can. That's where the weight transfer comes from. It most likely comes down to the pull bar usually mounted closer the the left wheel so the lr gets more of the transfer, compared to the lift arm. This LR loading makes the car tighter. Tighter seems like more traction, even when it isn't. These days, we don't slow down, so drag race traction is not the goal anyway. Consistent loading of all tires is.Quote:
Originally Posted by ZERO25
Are these types of pullbar still legal?
https://www.facebook.com/RaceKnowHow...5959663874750/
Or is this more like what they running now? I haven't looked under a mod in 20 years.
https://i.pinimg.com/564x/65/5b/1e/6...6b6e0e652d.jpg
I looked under Wallace's Elite back in November, and he was still running the DEI one. According to that video, Hoffman helped them in development. Jerovetz has developed a shock that works with it as well.Quote:
Originally Posted by KTMLew
There are just a few things going on. Some front to rear transfer of weight, depending on mounting points, lifting of the chassis, and redistribution of the weight on the rear tires due to the springs being unloaded, and cushioning of the torque of the rear housing from reaction to the axle torque.
The pullbar has a much bigger impact on the loads in the 4 link bars, compared to a lift arm, and that's where the violence comes from. This load is proportional to the load in the spring as the 4 link bars have to resist the rear being pulled forward.
Thats whats kinda confusing. You see that violence on suspension cams, and thinking that would shear the contact patch on those little tires!
Oh boy...thought I was in the Modified section...whoops!
I had no idea anyone is still running a pullbar on a latemodel. Last I remember seeing was Rayburn. That's been a while.
This is the only section with discussion, we do it all. I think Rayburn had a variation of the pullbar on his last reboot a few years back, but I'm not 100% sure.Quote:
Originally Posted by KTMLew
We had the last one he took to East Bay and made some shows with as a car owner and guy in charge. We raced it with a lift arm, but it didn't have that at East Bay.
2nd link the bsb brand
Also consider the spring or biscuit style pull bars typically allow more rear axle rotation and therefore, significantly more Panhard bar travel on the pinion end as well as moving the axle left/right at attitude.
Nowadays with the Pull Bars you will see a spring / rubber combo, and travel is usually an inch, to 1 3/8s or so max.
The rubber biscuits are better because they dont rebound so hard. Rates can be up in the 2200 lbs range at max travel.
Yes, but no matter if it's a solid pullbar, the rear end pulling forward under hike makes the pinion rise more then a torque arm in most cases. The closer to the rear end the pullbar is the more it pinions up from the rear end moving forward. Not that is right or wrong, just different and they have different dynamic J-bar rakes, dynamic left to right rear end positions, on gas vs off gas.Quote:
Originally Posted by Kromulous
I'm really surprised this much discussion about pullbars. I'd assumed it was long gone tech except for mods. THIS is why I come here. Love the tech stuff.Quote:
Originally Posted by billetbirdcage
Very well put. Seems like Joe Garrison was opposed to pullbars with 4 link too. I like pull bars, but I also like swing arms and/or most z-link suspension arrangements as well, but like you said having a pullbar with 4 link is just too violent to be consistent. Suspension setups are a system, or a package if you will and trying to do it "a la carte" is not usually a great result. You can end up with too much of a good thing, when balance delivers more speed. JMO.Quote:
Originally Posted by MasterSbilt_Racer