4 Bar length Preference??

[clbaker25x]

What is everyone's thoughts on which bar length is best for a 4 bar? Switching our car over to 4/4 next year and have put the brackets in. They have multiple holes so I can run either 16/14 (upper/lower) or 17/15. This is for an IMCA modified racing on 1/3 to 3/8 mile tracks Beatrice and Eagle. My understanding is that BMS runs 17/15 and JET run 16/14.What is everyone's bar length preference and why?

[RaceMentally]

What is everyone's thoughts on which bar length is best for a 4 bar? Switching our car over to 4/4 next year and have put the brackets in. They have multiple holes so I can run either 16/14 (upper/lower) or 17/15. This is for an IMCA modified racing on 1/3 to 3/8 mile tracks Beatrice and Eagle. My understanding is that BMS runs 17/15 and JET run 16/14.What is everyone's bar length preference and why? 17/15 imca 16/14 on any other tire besides g60

[langdonracing48]

i've always heard 17 on top, 15 1/2 on bottom works best. i liked the 16/14 better myself though. on the left rear bottom bar a bunch of us ump guys are adding a bolt in bracket to shorten it up to 10" center to center. i tried it for a while, then went back to my 14" bar. i think the 10" would be great on a decent track, but my home track is really slick all the time and it just made the car too unstable.

[clbaker25x]

So longer bar just makes it a little more stable and gives a little more drive on the slick? Does it make it index into the spring a little more with longer bars? Appreciate the help, this is on an impala stub older Jet mod that I put brackets on. Have been leaning towards the 17/15, but just because that is what I have heard BMS runs.

[langdonracing48]

i'd run 17/15 on the slick probably. indexing the birdcage into the spring slightly increases forward bite. usually only do like 2 to 4 degrees.

[RaceMentally]

Or just simply call up Jet and get brackets so you can try both. Simplest solution and have it your way.

[RaceMentally]

[QUOTE=clbaker25x;1754851]What is everyone's thoughts on which bar length is best for a 4 bar? Switching our car over to 4/4 next year and have put the brackets in. They have multiple holes so I can run either 16/14 (upper/lower) or 17/15. This is for an IMCA modified racing on 1/3 to 3/8 mile tracks Beatrice and Eagle. My understanding is that BMS runs 17/15 and JET run 16/14.What is everyone's bar length preference and why?[/QUOTE I noticed you already have brackets. Well those are strictly base set up bar lengths. Ive seen some of the good Jet guys running a 2" plus difference left to right. 13/16 left 16/17 right.

[clbaker25x]

My car is setup so I can run either a 15, 16 or 17 inch top bar and a 14, 15 or 16 inch bottom bar.What is the advantage to the longer lower bar on the right side? The short left lower for a quicker reaction, but not as good on slick? Again I appreciate the help.

[LM14]

Longer bar slows down movement and reaction times. We ran several different lengths in a 2011 Jet with an Impala stub and went back to the baseline every time. Shorter bars speed up movement and reaction time.

SPark

[clbaker25x]

Thanks everybody for the replies!! This 4/4 stuff seems pretty complicated. :)

[Anonymous24]

Long bars short bars....a 14 in bar does not swing faster than a 16 inch barBars move at equal speeds like a pendulum on a clock... Simple physics...what the bars do is change instant centers, roll center and CGH in dynamic, and rear steer. Lots of answers here that will just make you chase your tail.

[Ltemodel]

You will probably feel the difference in split in the bars more than the actual length difference. The more split you put in the right side bars the tighter the car will be.

The less split you put in the left side bars, the tighter the car will be. This is mainly because with more split on the right, the more and faster the birdcage will index into the spring. Opposite is true on the left, the less split in the length of the arms will index into the spring more and faster.

The total length of the bars will just determine the speed or reaction time of the rear suspension. When you stab the gas the car will tighten up quicker with shorter length bars as opposed to longer length bars. Track configuration and driving style will play the biggest role on what will feel good for you.

Be careful ...

The problem is, many guys get their car really tight and hurt overall lap times. A car that is well balanced will traction up faster than one that is too tight or loose. Don't be tricked into thinking that tight is always traction. It will seem that way sometimes, but it can slow you down.
Good Luck,
Kevin

[clbaker25x]

Thanks Kevin, plan is to ensure plenty of drive in left rear but keep the right rear free on entry. Hopefully it works!