Is J-Bar still adjusted to affect rear tire loading?

[KTMLew]

I give up. later folks.

[grt74]

yes but there are also other concerns, when you adjust the jbar, you can hurt your chain limiter, you may need to lengthen it, you won't see guys adjusting so much anymore except for springs and shocks, unless you have done your homework, the chain limiter affects alot when you make jbar and bar movements

or if you adjust the jbar say less angle, you may actually lengthen your drop measurement and not even know it, you'll have to do the homework, no quick fix

[MasterSbilt_Racer]

yes but there are also other concerns, when you adjust the jbar, you can hurt your chain limiter, you may need to lengthen it, you won't see guys adjusting so much anymore except for springs and shocks, unless you have done your homework, the chain limiter affects alot when you make jbar and bar movements

or if you adjust the jbar say less angle, you may actually lengthen your drop measurement and not even know it, you'll have to do the homework, no quick fix

To add to GRT74 comment, j bar changes get pretty drastic, pretty easily. Most people have their cars balanced pretty good these days. Geometry changes just aren't thrown around near like they used to be.

[fastford]

To add to GRT74 comment, j bar changes get pretty drastic, pretty easily. Most people have their cars balanced pretty good these days. Geometry changes just aren't thrown around near like they used to be.

I agree , but to me , thats whats missing from late model racing these days , I loved making big changes , if you hit something that night , it was sweet , most the time you went the other way though , lol , those days are gone though , late model racing is to refined these days , and technology makes it expensive ......JMO ....

[fastford]

I give up. later folks.

dont give up buddy , there is still a few of us on here , and probably some of the best tech info on any dirt late model forum

[KTMLew]

dont give up buddy , there is still a few of us on here , and probably some of the best tech info on any dirt late model forum

I just get frustrated with the whole I KNOW THE ANSWER BUT CAN'T TELL YOU BECAUSE IT'S A SECRET crap.

Since left side of J-Bar is now on a slider on just about every chassis very small adjustment should be easy enough. My question is more of a staying on 4 wheels surely is faster/easier to drive than 3. Seems like they've maxed-out the soft RR and 8 million lbs of crossweight. Cars are a teeter totter, LF to RR supported by topped-out LR and bottomed out RF.

I know I'm not saying anything everyone doesn't know. Why must everyone do the same thing? If you don't try new things never get faster. Guys that are winning can maneuver. Harder to do on 3 wheels. If J-Bar isn't causing the 3 wheeler deal, what is? LR is height limited by the chain, right? RF can only get so stiff or it pushes like a dump truck. Or not? Is it just learning to drive it without really having what i would call lateral traction at RF?

So many questions/theories. Very few seem to have the answer.

[MasterSbilt_Racer]

I just get frustrated with the whole I KNOW THE ANSWER BUT CAN'T TELL YOU BECAUSE IT'S A SECRET crap.

Since left side of J-Bar is now on a slider on just about every chassis very small adjustment should be easy enough. My question is more of a staying on 4 wheels surely is faster/easier to drive than 3. Seems like they've maxed-out the soft RR and 8 million lbs of crossweight. Cars are a teeter totter, LF to RR supported by topped-out LR and bottomed out RF.

I know I'm not saying anything everyone doesn't know. Why must everyone do the same thing? If you don't try new things never get faster. Guys that are winning can maneuver. Harder to do on 3 wheels. If J-Bar isn't causing the 3 wheeler deal, what is? LR is height limited by the chain, right? RF can only get so stiff or it pushes like a dump truck. Or not? Is it just learning to drive it without really having what i would call lateral traction at RF?

So many questions/theories. Very few seem to have the answer.

Every time you increase on on track ride height of the lr, you have to get the rf lower, or the LF is coming up. Yes, 4 tires will steer better than 3. But a higher spoiler grabs more air and gets more down force on the car.

The droop rule has done next to nothing to limit LR on track height.

[KTMLew]

Every time you increase on on track ride height of the lr, you have to get the rf lower, or the LF is coming up. Yes, 4 tires will steer better than 3. But a higher spoiler grabs more air and gets more down force on the car.

The droop rule has done next to nothing to limit LR on track height.

Is my understanding at limit of lowering RF due to rack mount contacting ground. Whole idea for AK's straight axle. Modern Cup cars and FWD street cars have the rack mounted way up high. Steering arm is nearly at top of spindle. Is there a rule against that or like AK's deal, fan is in the way? Rack could be mounted above fan/water pump area. Of course bump steer gets ugly but let's do this one step at a time...

[MasterSbilt_Racer]

Is my understanding at limit of lowering RF due to rack mount contacting ground. Whole idea for AK's straight axle. Modern Cup cars and FWD street cars have the rack mounted way up high. Steering arm is nearly at top of spindle. Is there a rule against that or like AK's deal, fan is in the way? Rack could be mounted above fan/water pump area. Of course bump steer gets ugly but let's do this one step at a time...

Eventually, the lower control arm mount gets in the track, or some other pieces. Everything can't be up high. If it is, your chassis would be flimsy, engine sitting way to high, or other issues.

There's no rules against moving the rack and tie rods. The rack and mounting is not what hits first on our modified Mastersbilt cars. We have a bunch of things hitting at the same time. There's always packaging compromise and dlm are mostly the way they are because the original design was not made to be used they way the cars are used today. Small, incremental adjustments have been made over time to a design that was never intended to be used on a down force race car where operating ride height and static ride height must be so different due to rules.

[billetbirdcage]

There's no rules against moving the rack and tie rods. The rack and mounting is not what hits first on our modified Mastersbilt cars. We have a bunch of things hitting at the same time. There's always packaging compromise and dlm are mostly the way they are because the original design was not made to be used they way the cars are used today. Small, incremental adjustments have been made over time to a design that was never intended to be used on a down force race car where operating ride height and static ride height must be so different due to rules.


Is my understanding at limit of lowering RF due to rack mount contacting ground. Whole idea for AK's straight axle. Modern Cup cars and FWD street cars have the rack mounted way up high. Steering arm is nearly at top of spindle. Is there a rule against that or like AK's deal, fan is in the way? Rack could be mounted above fan/water pump area. Of course bump steer gets ugly but let's do this one step at a time...


Actually there is a rule on rack placement in a way from another AK rule, when they did the front suspension rules.

Tie rod on spindle has to be between below the spindle snout, so you can't have the tie rod high on spindle to allow the rack to be moved higher and still get bumpsteer right.

[billetbirdcage]

Whole idea for AK's straight axle.


Austins straight axle was not for rack clearance to the ground. The primary reason was for consistent camber the the ground no matter how the car rolled. The whole rack deal was a by product of the straight axle and needing to clear the fan and fan spacer as he has said he thought driver induced rollsteer on the steering wheel would be a problem and went thru all the variations of steering by not wanted the rack on the axle. <-- what finally solved most of the issues and allow more options in making everything clear.

[MasterSbilt_Racer]

Actually there is a rule on rack placement in a way from another AK rule, when they did the front suspension rules.

Tie rod on spindle has to be between below the spindle snout, so you can't have the tie rod high on spindle to allow the rack to be moved higher and still get bumpsteer right.

I had forgotten that one! But, there's still holes to fix the bump steer.

[billetbirdcage]

Also remember they added no electric steering, LOL. Right before the new drive by wire car was about ready, shrugs

[KTMLew]

So...Chassis X says J bar should be at Y degrees. But you manage to trick the system and get LR/deck 2" higher than spec'd while on the track. Angle has just changed. Nobody cares? More angle loads RR more, correct? Keep hearing about aero being most important. What makes contact with the track?

Don't mean to sound pizzed-off. Just don't understand how we got to only thing that matters is loads measured with a smasher.

[MasterSbilt_Racer]

So...Chassis X says J bar should be at Y degrees. But you manage to trick the system and get LR/deck 2" higher than spec'd while on the track. Angle has just changed. Nobody cares? More angle loads RR more, correct? Keep hearing about aero being most important. What makes contact with the track?

Don't mean to sound pizzed-off. Just don't understand how we got to only thing that matters is loads measured with a smasher.

More angle means more load at the point it attaches to the rear. That point is closer to the rr, generally speaking, so you should see increased rr loading. The j bar has basically zero suspension compliance, so that's definitely a concern. So, you can definitely go too far, but beyond that, there's no perfect angle. It determines the roll center and if it's vertical your suspension is solid.

Not sure I understand you aero question. Tires make contact with the track. Aero is large down force on those tires, beyond the vehicle weight, that makes it's way to those tires, from the body, thru all the connections between the tires and the body.

Loads measure with the smasher are just a reference. In that regard they still are not the correct loads for what is seen at some point in actual operation. The physics affecting the cars have never changed. It's only the reference people choose to use to chase a good baseline.

[MasterSbilt_Racer]

Additionally, any load carried by the j bar is load that cannot be carried by the 5th coil, 4 links, LR spring, or RR spring, because the j bar has taken it. Load on the rr spring would do a whole lot more to "stick the rr".

[KTMLew]

Additionally, any load carried by the j bar is load that cannot be carried by the 5th coil, 4 links, LR spring, or RR spring, because the j bar has taken it. Load on the rr spring would do a whole lot more to "stick the rr".

Doesn't seem like modern setups use RR spring very much at all. Next to no support there. Just let it lay ona bump stop. IMO the J-bar is doing more to support RR than the spring. Does anyone still make a springbar J-Bar that has some cushion? I was around this stuff back in the day when nearly every bar that was in compression was a spring bar. Consistency was the issue. ridiculous amount of maintenance required.

Your mentioning the 5th coil made my brain wonder...wouldn't J-bar, which is right side of pinion mounted, tend to counter the torque arm movement to some degree? I realize leverage is a thing. Load cells everywhere. We need load cells and MORE COMPUTERS!

[MasterSbilt_Racer]

Doesn't seem like modern setups use RR spring very much at all. Next to no support there. Just let it lay ona bump stop. IMO the J-bar is doing more to support RR than the spring. Does anyone still make a springbar J-Bar that has some cushion? I was around this stuff back in the day when nearly every bar that was in compression was a spring bar. Consistency was the issue. ridiculous amount of maintenance required.

Your mentioning the 5th coil made my brain wonder...wouldn't J-bar, which is right side of pinion mounted, tend to counter the torque arm movement to some degree? I realize leverage is a thing. Load cells everywhere. We need load cells and MORE COMPUTERS!

When I say rr spring, I mean everything on the coilover that takes load. The cars are not traveling much on the rr. Be it metallic or rubber or plastic, it's supporting weight.

[KTMLew]

When I say rr spring, I mean everything on the coilover that takes load. The cars are not traveling much on the rr. Be it metallic or rubber or plastic, it's supporting weight.

They have become large go-karts. Tire is the suspension. So...back to loading...

[MasterSbilt_Racer]

They have become large go-karts. Tire is the suspension. So...back to loading...

Thats true to some extent. It's entirely true if you are an average to bad car.

[Ltemodel]

I see something that keeps getting overlooked by guys trying to get more height on the LR. When running a beam axle, you will need to also increase the roll angle or you will start pulling load off the right rear when increasing the height of the Lr.

[Kromulous]

Secret to more LR Hike, is compressing the RR, and keeping it compressed.

[MasterSbilt_Racer]

Secret to more LR Hike, is compressing the RR, and keeping it compressed.

I thought it was just a longer chain.

[Kromulous]

Well, that too.

But the Chain, a tight Chain, is just a pivot point, from right to left.

In my humble opinion, and often wrong... LOL

[Jim11h]

Ok masters, that comment has my attention, what are you beating around the bush about?

[MasterSbilt_Racer]

Ok masters, that comment has my attention, what are you beating around the bush about?

I was honestly just being a bit dense/sarcastic.

The droop rule and how high your deck gets comes down to 2 thoughts.

1) how's it hanging?
2) how do you increase LR displacement with similar roll angle?