Question to the flex gods while building the Rat I have tryed to build a ballanced overall rig but now its done and we flexed it on a 30 deg ramp today to measure for new front shocks and the new Driveshaft its getting so out of cureosity what is an ok score, fair, and just dam good and just funking outrageous. I dont no who makes the rules for scores and would like to no a little more how they derive them

Here is an RTI calculator: http://www.izook.com/tech/math/rti_ramp_calculations.htm


RTI is a way of measuring your vehicle's ability to flex.
It is measured by how far up a ramp (standard is 20 degrees) the vehicle can go while still keeping all four tires in contact with the surface underneath. Variables such as vehicle length, suspension, and so on are compensated for by using the following equations:
The number of inches a vehicle travels up the ramp before running out of suspension travel (when a tire leaves the ground), divided by it's wheelbase. Then multiply that figure by 1000. A perfect score would be 1000, that is, the vehicle can go as far up the ramp as its wheelbase without lifting a tire. Stock vehicles do not do this, but modified rigs can reach and exceed that depending on how much customizing has been done. To compensate for extreme machines, a 23-degree and even a 30-degree ramp have been used. The calculations are the same, just be sure to mention which standards you're using when you brag.

Simplified: Inches Traveled divided by Wheelbase, multiply by 1000, equals RTI

I feel that anywhere near a 1000 is good, if the flex is balanced. On a 23* my Sammy ramps a 1120. My .02:)

Ok I understand the calc except where you say the distance traveled up the ramp. on a 30 deg ramp if I drove my left front tire up the ramp 71" or is it measured after stoping from the bottom of the tire to the ground directly below say 43" ??
In this case I was on a 30deg ramp and drove 71" measured from the start of the ramp to the center of the wheel hub. that is where my left rear tire would still stay on the ground.

With my rear shocks limiting my down travel I get about an 1150 on a 20* ramp or about a 1000 on a 23* ramp.

Overall the flex is pretty balanced front to rear with the YJ's and spring over.

Here's a reverse RTI calculator where it will figure out your score based upon how high off the ground you can get the wheel before lifting a tire.

http://mark.legendz.com/ramp.html

what is a typical RTI score for a 23* ramp for having nothing but the frame, tires, shocks, and completed suspension(basically everything minus the body) be?
-justin

i just punch in the numbers on one of those calculators and i measure the distance to the ground from the tire up on an obstacle like a boulder on a flat spot or a telephone pole in the parking lot:D :D i just measure the distance to the ground and plug it in the calcs and get my #. with my shackle and cj's in the rear and rears up front i get about 1200 on a 20. haven't plugged in for the 23 deg but i would think it is about 1000 like everyone else. there are so many ways to cheat on a ramp it is not even funny. like airing down and using massive buggy leaves and huge foot long expander shackles. i dont put much weight on an RTI score unless the flex is well balanced front to rear.

A 1000 RTI occurs when the center of your back tire is at the base of the ramp. Because you got 100% of your wheelbase to go up the incline. (RTI = percent of wheelbase up the incline X 10)

A 1000 RTI on the "standard" 20-degreeramp works out to a 700 on the steeper 30-degree, which is what is used in places where the trucks are extra-flexy, like the Top Truck Challenge.

Here is (http://www.rockskullz.com/rticalculator.htm) a pretty simple RTI calculator. All you need to know is the gap between the bottom of the to the ground, and how long your wheelbase is. Mine works out to about a 1,020 on a 20-degree ramp (36" travel, 103" wheelbase)

I think my stock Sidekick would score about a 36 LOL. Actually, I think I WILL try to find a ramp, to measure it, before I start my mods. Anybody else ever measured a stock rig?

Originally posted by fatkid
I feel that anywhere near a 1000 is good, if the flex is balanced. On a 23* my Sammy ramps a 1120. My .02:)

I'd like to see a picture of this :)

Gee all this ramp talk. WOW, I thought ramps were just for posing? I agree with fatty, well ballanced is what your looking for, and anything over 1000 will work well. If you don't have a ramp, a Jeep works well in a pinch.:D :D :D

http://ovo.ca/delormer/superlift2001/S_S_mudlite-humping2.jpg

Or a nice set of ruts...
http://home.off-road.com/~mithrandir/flex/flex15.jpg

That's the biggest damn samurai I have ever seen! :flipoff2:

Originally posted by Bobzooki
I think my stock Sidekick would score about a 36 LOL. Actually, I think I WILL try to find a ramp, to measure it, before I start my mods. Anybody else ever measured a stock rig?

Stock LWB Sidekick gets around 430 on a 20 degree ramp. Not bad considering the fundamentals. Removing the front roll bar is worth about another 30 points.

r@m

Originally posted by mudlite
...well ballanced is what your looking for, and anything over 1000 will work well. If you don't have a ramp, a Jeep works well in a pinch.:D :D :D


An easy way to check the balance is to use a (large) set of matched car ramps. Use them under opposite (diagonal) tires. When you get on top of the ramps, you will see if it is balanced (hood will be level across the front). If not, you can tweak it there in the driveway before hitting the trails. It's alot easier on a controlled location like a set of ramps instead of a muddy ditch...

I scored a 960 on a 30 degree ramp after my SAS compared to the stock 450. This is at street tire pressure.

Here's a picture of mine on a ramp of unmeasured angle:

http://www.off-road.com/suzuki/reviews/images/cssusflex01.jpg

You see the bend in the ramp? That was created by Ron Conley's Samurai. His front bumper is particularly heavy, and that's as far as he could get up the ramp with his Calmini 5 inch shackle reversal kit. Obviously, the YJ spring shackle reversal setup flexes a bit better.

http://www.off-road.com/suzuki/reviews/images/cssusflex02.jpg

It won't ramp 1000 on a 90 degree ramp, but it's more flex than I need. I feel that articulation is subject to the law of diminishing returns. A lot of articulation is great, but an insane amount of flex isn't going to get you much (if any) further. By the time I'm lifting a tire off the ground, I'm already leaning so precariously that additional articulation wouldn't help me any. I'm extremely pleased with this setup for its flex, ride quality, and simplicity.

here's a ultra-poseur ramp shot of the old air- beater-zuki......:p http://www.nsor.com/showcase/2001/sns2001/sns-8.jpg
the score was 1130 on a 30 degreee ramp ( note the primer on the hood from constant 'glass repairs due to rolling the truck on every trip )