Jeepspeed engineering

[Larrythedog]

To the Original Poster of this thread. You could build a jeep to race like a rally car.. But why? As Andy said if you "think outside the box", anything could be done to the spirit of the rules. I honestly see most of the Jeepspeeder's on a limited budget, so the use of exotic materials would be non-existant. I would like to see a Jeepspeed rig built with the full body lightening, and structural stuff we do to conventional Rally cars. But then again If some one spent the time and money to build such a Rig, they would be protested at the first event they showed up at.. So save your pennies, and dream big..

Try to lighten the body of a Jeepspeed. Just dont plan on racing it longer than a year.

 

[Weasel]

For the OP, no I don't know if much "racing" type analysis goes into JS trucks. There isn't much or any discussion about roll centers, moments, camber curves, etc directly, or chassis stiffness, engine/tranny cooling requirements, analysis of components, etc, etc.

It's more of a trial and error approach where people fine what works well and continue to develop that.

Some of the larger and more well funded teams may have some of this type of design work but it's not widely published. I do know some of the components on the higher end stuff is designed by some guys that have a pretty good design/engineering background.

So no it's not like F1 or Ralley where everything is analyzed and optimized to the greatest extent possible.

 

[Mike1331]

What is needed to tune the chassis? we'll start there. the XJ is a SWB vehicle so going over bumps will easily make it slide going down a bumpy straight line. and how stiff do you want the chassis, i would imagine that you don't want it to stiff because it to absorb energy, not reject it . and since these vehicles are gutted to the bone and being front heavy the rear end has no weight and will slide around corners so would a ballast, or even a wing to produce down force, help keep the rear planted to the ground. and what about center of gravity? does the driver sit lower and the roof replaced with a light weight material ? do teams thinks of these things
As for Mike1331, your link was not the answer, sorry man

have you even looked at the roof of your xj? its quite thin as it is as is the rest of our chasis. 16 gauge... I gave you a link that should show you what it takes to build a competitive jeepspeed which is what you asked. Search...there's build threads everywhere that depict what it takes, and its all been pretty much optimized. or go build a rally car if that's what you want, that's a whole other animal...i just picked up a 91 audi quattro 20valve 5 cyl i'm gutting and caging...can't wait to rally it.

 

[I Beamed Jeep]

Here is a link to a much cleaner build maybe more what your looking for.
http://www.naxja.org/forum/showthread.php?t=1043068&highlight=money+build
IMO jeepspeeds are just like rally cares "uni body" only thing is were all a bunch of poor bastards building them with no knowledge.

 

[DieselSJ]

Zulu...

First, off road racing and rally are two totally different types of racing. Rally is smooth dirt. Cars are set up more like a road race car with a little additional travel. Off road racing is going as fast as you can over some of the nastiest terrain you have seen. Venture over to www.race-dezert.com and look through some of the videos over there. Wings and sliding corners and all the other stuff you are asking does not apply.

Chassis - you want it stiff. Flexing chassis will crack. Let the suspension do all of the work. Reinforce everything.

A few pics of our build...

 

[Zuul99]

You sir have been the most helpful. I see that you have removed some metal. now what about a ballast to keep the rear end planted? if nothing is back there whats going to keep your rear end from fish tailing

 

[DieselSJ]

You sir have been the most helpful. I see that you have removed some metal. now what about a ballast to keep the rear end planted? if nothing is back there whats going to keep your rear end from fish tailing

We haven't removed any metal - the rules do not allow it. The hole in the roof was the factory sunroof, which we have converted into a scoop for the oil and trans coolers that are mounted in the rear. Our fuel cell is mounted in the rear, as are both of our spare tires. With this type of racing, we aren't going through high-speed corners so fishtailing is not an issue.

 

[DieselSJ]

Check this -

http://www.youtube.com/watch?v=L5NOuEHS7Fc

 

[Zuul99]

that was a pretty cool vid. I was looking at the terrain and such, How would sportsman such as your self set up the Jeep for different terrains imagine each course is different so do you guys just go into the race hoping your set up will work. Or do you set up the truck depending on the terrain. Like if a course is very rocky do you adjust the suspension and use a thicker tire

 

[DieselSJ]

We have a suspension setup that works well everywhere. The courses are all pretty similar. If we get out to the course and it is harder, softer, smoother, rockier, or whatever, we might make adjustments to the bypasses on the shocks to soften or stiffen. But gnarly jacked up desert terrain is pretty much gnarly jacked up desert terrain. You get some variations from location to location but not enough to worry about different suspension setups. All courses are rocky...we only run 1 tire - Goodyear MTR is where it is at.

 

[Zuul99]

Do the shocks work similar to a mountain bike shock but on a much larger scale. meaning do these shocks have a rebound and a compression dial(s)

 

[DieselSJ]

Do the shocks work similar to a mountain bike shock but on a much larger scale. meaning do these shocks have a rebound and a compression dial(s)

Sort of, but not really. Overall valving is set internally on the piston. We run bypass style that allow oil to bypass the piston at certain points of the travel, which effectively changes the valving based on where the shock is in its stroke. The bypasses are adjustable for how much oil they flow.

http://www.bilsteinus.com/products/off-road/9100-series-external-bypass.html

 

[Zuul99]

How about differnt gears? are different gears used for different terrains

 

[DieselSJ]

How about differnt gears? are different gears used for different terrains

Nope. But the gears used from team to team varies greatly. I've heard everything from 4.56 to 6.xx+. But once you set the car up you typically stick with that ratio for everything.

 

[Zuul99]

6.x gears? those are huge! is that used for a hill climb like course.

 

[Darky]

I'm no racer, but it's likely for getting more power out of the rig in order to keep the tires moving in heavy silt.

 

[DieselSJ]

6.x gears? those are huge! is that used for a hill climb like course.

You really don't understand the sport, do you? This is "desert" racing.

 

[Mike1331]

You really don't understand the sport, do you? This is "desert" racing.

was going to say this earlier but didn't want to be the naysayen cyinicist harping on a lost young dude... I will say sir you have way more patience then I do so kudos to you… Hopefully that’ll all change when I become a father.

 

[DieselSJ]

was going to say this earlier but didn't want to be the naysayen cyinicist harping on a lost young dude... I will say sir you have way more patience then I do so kudos to you… Hopefully that’ll all change when I become a father.

I really don't mind answering questions, but at least make an effort to research the sport.

You will learn infinite patience when you become a father. I certainly did!

 

[Zuul99]

I knew this post would come, and i have researched the sport even downloaded the rule PDF(along with LMP1, LMP2,GT rules ), but rules build pix only go so far, i wanted know what it actually takes and what sort of thought process goes into building one. sorry if my questions seemed far out, formula 1, ALMS, WRC came at least 7yrs before i discovered Jeepspeed. I thank you all for being patient, and for giving me loads of knowledge and information. So again thank you. if you guys have any questions about million dollar racing machines i will return the favor, Haha