Rocket short bar brackets

[shadowj38]

I recently swapped my LR spring out for a 16" 125 barrel spring. I like the way the car feels now but I've noticed I need to be much smoother with the pedals because the car seems to react much faster now. The car came with the short bar brackets on both top and bottom of my Lr. I've been looking at a bunch of cars in the pits and pictures of cars for sale on the internet and it seems not many people run these brackets anymore. Atleast not both of them. I've been thinking of taking them off this year to see what it does. What are some pros and cons of running these vs. Not running them? This is on a blue front rocket. Thanks.

[phenom08]

What kinda motor, what size tracks,

[shadowj38]

430 open steel block. 3/8 mile tracks

[phenom08]

I would start with the long top bar, and short bottom bar with 13.75 drop

[shadowj38]

Kind of what I was thinking of trying. Didnt want to take both off and change too much. Thanks

[shadowj38]

Phenom08 can you explain your reasoning? I'm trying my best to learn and understand these cars. Thanks

[phenom08]

We run the short top bar with crates or small tracks. Car will turn more when u pick the throttle back up. The long bottom bar can make it hard to climb the bars if there's no moisture to put the lr in

[shadowj38]

Thanks for the reply

[Mopar DLM]

what are the lengths of the long and short bottom bar?

[shadowj38]

I'm not positive on this, I'll have to check in my book but I believe 15 1/4 for the short bar. I'm not sure on the long bar. I don't believe my book says.

[Dirtmod13]

I think top bar is 18-18.25 if I recall

[Burke1118]

Length of bar has far less effect than angle. Shorting the left top 2” would have a smaller effect than just going up a hole. I remember looking into 16 vs 15” lower bar, and after plotting it out on my computer, it made something like a 1/16” difference in steer and maybe a degree of indexing difference. No driver in the country could feel that.

[95shaw]

The starting angle at ride height may be an even bigger effect of short bar vs long bar.

[billetbirdcage]

OP should be talking:

LRU bars at either 18.25 or 16.75 with shortener bracket
LRL bars at either 17.0 or 15.0 with shortener bracket

Assuming 25 degree static upper and 12 degree static lower bar angles and almost 5" of travel at cage (this brings the long upper bar close to 45 degree's at full hike), these are the following rollsteer, index and thrust angles at full hike (note this is only measured at the cage not at the wheel)

18.25 LRU and 15.0 LRL:

2.715" of steer
38.87 degrees of thrust
9.36 degrees of index on cage

16.75 LRU and 15.0 LRL:

2.781 of steer
40.16 thrust
10.174 index

18.25 LRU and 17.0 LRL

2.645 steer
37.87 thrust
10.259 index

That being said: While it doesn't look like much of a change I don't know a driver yet that hasn't been able to feel anyone of those changes.

#note: when bar length was changed, the static angle was not changed still the 25 or 12 degree static

[Dirtmod13]

Billet, What program did you use to mock up the distances and calculate index?Sent you a PM

[billetbirdcage]

I use mastercam

[shadowj38]

Thanks for the reply Billet. Based on that info, which combination do you think I should start with?

[billetbirdcage]

Honestly without knowing for sure what bar lengths you was running before since you just said extensions on both. I believe most all older blue cars used a bolt in lower extension to get to the std 15" lower but some of the newer ones had one piece brackets that needed no extension.

I'd probably go with what phenom08 said, 18.25 LRU and 15.0 LRL bar and adjust from there. I'm not a fan of the long lower bar but in some instances it works but even less often with today's set-ups.

Double check your lengths to make sure what you had been using.

[spiderma4]

Honestly without knowing for sure what bar lengths you was running before since you just said extensions on both. I believe most all older blue cars used a bolt in lower extension to get to the std 15" lower but some of the newer ones had one piece brackets that needed no extension.

I'd probably go with what phenom08 said, 18.25 LRU and 15.0 LRL bar and adjust from there. I'm not a fan of the long lower bar but in some instances it works but even less often with today's set-ups.

Double check your lengths to make sure what you had been using.

billet I have a car that has 17 top 17 bottom length rods what type of track or track conditions would that work or should I go to 15 or so bottom? or maybe run a lot of angle on bottom?

[CCHIEF]

billet i have a car that has 17 top 17 bottom length rods what type of track or track conditions would that work or should i go to 15 or so bottom? Or maybe run a lot of angle on bottom? hijack alert!! loaded question alert!!

[spiderma4]

hijack alert!! loaded question alert!!

why? am I missing something? I guess all iam asking is what conditions does the long bottom rod work in? if it works only works on a reverse bank donkey track and I don't race at one then I know not to waste my time. no one on here owes me anything if they don't what to answer the question that's fine I will plug way at it like I always do.