Parallel LR Bars

[TwistedFrame21]

Looking at a good starting point on angles and lengths to run the lr parallel bars? Doing some updating on a black front rocket with 604 crate. Still need to have 4 1/2” separation top and bottom?

[MasterSbilt_Racer]

You don't have to have 4.5" separation. Other stuff will work and might be better. Once you head down the path of altering the geometry, there are limitless possibilities. Some will be better at certain times than others. No one who has something outside the box is just going to give it to you. Setting the bars at say 17" each with the average angle of your original setup will yield decent results.

[Basecircle]

Maybe I’m way behind on something, but what’s the theory on running the bars parallel? As the birdcage rotates they wouldn’t stay perfectly parallel anyway. Just trying to stay close?

[Austin34471]

They wouldn’t stay parallel if they weren’t to begin with. Running them parallel would negate any effects that indexing or “the hook” (spring behind) would have.

[MasterSbilt_Racer]

Basecircle, If the bars are parallel, there is no rotation. As Austin stated, no rotation leaves you with linear travel (axle vs spring deflection) instead of a digressive deal. That may or may not prove to be an issue as far as "getting on the bars".

[Basecircle]

never mind. I was thinking too hard (or not hard enough maybe). I’m so used to the birdcage index changing with travel that I couldn’t imagine it NOT. Had to draw it on paper. Just a parallelogram that the angles change with suspension movement/hike. Thank you!

[CCHIEF]

That long LR lower/lack of index can make the car real lazy getting up....better have some serious preload...or good traction.

[Matt49]

The bars starting parallel will only result in no rotation/indexing if the bars are the exact same length...which is rarely if not never the case. Not sure if that was implied somewhere that I missed but thought it was worth mentioning.

[MasterSbilt_Racer]

The bars starting parallel will only result in no rotation/indexing if the bars are the exact same length...which is rarely if not never the case. Not sure if that was implied somewhere that I missed but thought it was worth mentioning.

Good point. I made the assumption, but didn't state it.

[MasterSbilt_Racer]

That long LR lower/lack of index can make the car real lazy getting up....better have some serious preload...or good traction.

Be a good place for a "spring" that had a very low rate, meaning the load doesn't drop off much with extension travel. Wonder where a guy might get something like that?

[TwistedFrame21]

The few that I have seen are running the left lower down on the cage around 5 1/2”

[Kromulous]

Running the lower bar, lower down on the cage would make for some indexing, if the top was 4.5 and the bottom was 5.5". I guess it would make the indexing in a bell curve fashion, really index the cage as the bottom of the travel, the last couple inches of travel the BC would really try to cam FWD.

Swartz Chassis that we're running now is a 17" bar car, top and bottom on the LR. I have never tried this adjustment but i might soon. I am running the bars more parallel than i ever have, but finally got my shocks valved up to have enough compression. So will see how it work soon, if it ever stops raining !

[TwistedFrame21]

Running the lower bar, lower down on the cage would make for some indexing, if the top was 4.5 and the bottom was 5.5". I guess it would make the indexing in a bell curve fashion, really index the cage as the bottom of the travel, the last couple inches of travel the BC would really try to cam FWD.

Swartz Chassis that we're running now is a 17" bar car, top and bottom on the LR. I have never tried this adjustment but i might soon. I am running the bars more parallel than i ever have, but finally got my shocks valved up to have enough compression. So will see how it work soon, if it ever stops raining !


4.5 separation? Just added more angle on lower by going up on frame?

[Kromulous]

Well, most BC's are 4.5" on the top and bottom, the BSB ones i run you can run the bottom bar lower by 1/2 inch at a time. So you could run the lower at 5.5" I have never done it thou. I have heard it will help crate cars turn in better, but that is just what i have heard...

Anytime you introduce a bias with the connection points, meaning one point is closer or further from C/L, you will get some sort of change during travel.