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How would you manually change the wheelbase?

1K views 14 replies 5 participants last post by  pbmcauliffe 
G
#1 ·
I was thumbing through the preliminary ARCA 2002 rule book and I noticed that manually changing a vehicles wheelbase will be allowed (pending approval of the rule book). How would this be accomplished? We have several good fabricators on this board. How would ya'll do it?
 
#2 ·
I have a freind is working on fabricating a rig with hydraulic rear frame rails, that will allow the rig to stretch its WB 10".
I sure hate to see rock climbing going that direction though, I mean you get computerized hydraulic leveling suspension, rear steer, and adjustable wheel base, and its more like driving a video game, before long.
It sure is good to see, regular ole Jeeps(although well engineered and modified), still taking top honors on a regular basis over all of the fancy, high dollar Super Buggy's.

Jeff
89 YJ
Adversity is imminent, versatility is mandatory, misery is optional.
 
G
#3 ·
That is one of the things that really sticks out in the competitions. You're able to see a well-build, modified, non-sponsered rig spank the custom, deep-pocket teams. I'm always surprised at the innovation, however. And it's fun to see what works and what doesn't.

 
G
#4 ·
If you had enough slip in the drive shaft, you could mount the rear suspension on a slide mechanism similiar to the slider on semi trailers. It basically means having a subframe for the suspension, with some type of indexed rail system. The semi trailers use about a 1-1/4" pin at each side of the subframe and this locks into a hole in the frame on the trailer. You manually release the pins, and set the trailer brakes, then slide the trailer wherever you want it along the rails. Next time you are passing a trailer on the interstate, check and see if it is a slider, and you will pretty easily see how they work. Some even have systems that will release the pins via a brake can attached to the release mechanism.

Cage Up, Wheels Down
Jeepfiend
All my Jeeps are in pieces! Except for one!!
 
#5 ·
Rubicon Express (I think!) sells those little plates that replace the center pin and allow you to move the axle around ~2" Otherwise you can use leaf springs that are already off-set (Like H8Monday is using the fron leafs from a Grand Wagoneer or something) or switch to a coil suspension with the brackets welded further forwards. You can only move the fron axle forwards 2" max without causing steering problems.... (unless you run stand-alone hydraulic steering which is illegal on the street. Once the engine dies and stops spinning the hydraulic pump you could no longer steer!)

'89 Comanche, '89 Wrangler, '74 Postal
 
#6 ·
My front axle is now actually located about 5" forward of the stock location. It is not to hard to solve the steering geometry from that location, under my configuration. I went with a straight pitman arm about 6" long to get the drag link to the backside of the tie rod, and to keep it high enough to avoid binding at full compression on the driver side. It steers great, in fact the long pitman arm shortened my steering radius, by allowing me to go further lock to lock. It has a little bit of bumpsteer now, but i didnt notice it untill I was doing some high speed runs through the bumps at the sand dunes of Johnson Valley. The hydraulic ram assist steering that I will be fabricating this weekend will eliminate that bump steer.
The front axle being placed where it is now gives me a 99"-100" WB (depending on how the front suspension is sitting), it is awsome on steep climbs, it has an excellent ballance, and steers into corners better than before. It felt agile like a cat on the Hammers a couple of weeks ago. the rear axle is almost ready to swap, it will be located another 5" rearward for a total WB of 105". Cutting brakes will help to maintaine a tight turning radius, with the longer WB. That and the fact that I have pulled off over 400 lbs of weight at the rear end, (and 500 total for a total overall weight of 3650) makes the ole YJ a long, lean rock climbing machine.


Jeff
89 YJ
Adversity is imminent, versatility is mandatory, misery is optional.
 
#8 ·
Ill take some pics this evening, while Im wrenching and post them. Those kinds of pictures can be confusing, but I should be able to relay the idea, clear enough.

Jeff
89 YJ
Adversity is imminent, versatility is mandatory, misery is optional.
 
#9 ·
-snip-I have a freind is working on fabricating a rig with hydraulic rear frame rails, that will allow the rig to stretch its WB 10". -snip-

Hey Jeff
Whats the deal with this? Is it telescoping frame rails? I'm very interested if I can still compete legally. Short wheelbase for tight sections, then stretch it out for the steeps!!! What about the drivshaft?

I also moved the front axle forward about 4" but the drag and pitman arm would hit the tierod(tierod on top of knuckles). A friend of mine made me some custom steering arms that move the tierod behind the axle that are very cool (IMO).



Wayne @ Big Island RockCrawlers
"PYRO" The Rock Crawler
Web Site: http://www.members.tripod.com/surfmac/Index.html
 

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#12 ·
Here was my solution to the steering with the axle placed forward.
I ran a straight pitman arm to keep my drag link high enough not to bind on compression. The fact that the drag link starts behind the Tie Rod doesnt seem to affect anything since as the shackle reverse suspension is compressed it also moves the axle rearward, and keeps the drag link and tie rod from binding. What can I say it looks unconventional, but it works very well, and most of you have seen how much my rig can flex(not like Waynes, but still has very good compression and droop travel).
I think I will do something like waynes set up, when the D60 is swapped this winter.
Here are a couple of pics.



Here is a pic of the Jeep, with axle moved forward, the rear will be moved back, about 6" this weekend.


Jeff
89 YJ
Adversity is imminent, versatility is mandatory, misery is optional.
 
#13 ·
H8,
cool pics now I realize I was putting too much thought into moving the axle foward, doesn't look like it will be a problem now. I want to move the front axle as foward as possible cause I can't move the rear axle back due to the huge gas tank I have.

 
#14 ·
Yeah, i will be cutting away the bed and raising the gas tank, beginning tonight. I may go with a 26 gallon fuel cell, in the future, Im not sure yet. I have a good idea on how, im gonna raise the tank and reconfigue the bed using the stock 20 gallon plstic tank. ill know for sure in a day or two.

Jeff
89 YJ
Adversity is imminent, versatility is mandatory, misery is optional.
 
#15 ·
Jeff-
It may not be enough of a raise (about 4"), but when I moved the tank up on the CJ7 I cut a 1" wide section out of the stock crossmember for clearance, moved the factory mounts up to the bottom of the top frame rail, (tank can still be dropped straight down for service). After that I decided I didn't want to cut out the rear of the tub, so I made brackets to lower the tank back down 1.5" to clear the tub. I then rebent/cut the factory skid to fit again with an overall clearance gain of 2.5". I guess your going to have to raise it more than than since your are going back that far.

pbm
There is a difference between being Educated and Intelligent!
 
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