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Optimum wheelbase

Discussion in 'HardCore Corner' started by hammerhead, Oct 16, 2003.

  1. hammerhead

    hammerhead

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    Am in the design stages of a truggy project to be. Have most of the drivetrain, some of the steel, and all of the headaches staring me in the face and still can't decide exactly how big to make this dang thing. It'll be used for rockcrawling on slickrock and in wash bottoms with boulders. Mostly in Southern Utah but may venture out if successful. I've seen everything from Jon Bundrants "Tiny" to "The Ogre" with its 50" tires. Don't want to be that big or that small. A lot of folks think the 105" wheelbase is the magic number but that seems a bit long compared to my 40. Any input? Any suggestions?
     
  2. wngrog

    wngrog SILVER Star

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    105" is about normal these days.

    Depending on how tall you want your rig is how you need to determine how long you want to make it.

    The Waggoner/Proffit rigs that are 125-135" long are all running SUPER tall rigs that have the belly pan clearance to accomidate for such a long vehicle and the breakover.

    I have tried to keep Kate as low as possible (23" at the belly versus 36" for a Proffit Cruiser) and because of that, I feel that I am limited to around 105" or I will be getting hung up on the belly on everything.

    Point is, the higher you are, the longer you can be....

    Make it long and low and you will be dragging the belly on everything out there.

    My next project has Kate at 105"
     
  3. the shed guy

    the shed guy

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    Anywhere from 100" to 105" is good, and since you referred to a 40, 100" in a 40 with a 4" lift and 38's with a 6" wider track would be good [my 40 was 98"] and nice and stable.

    An 80 series is 112" from memory, and 6" wider than a 40 in track already, so wider rims and bigger tyres with a big lift to clear the belly would be good too, but not as easy to manouvre in tight spaces.

    A 60 is 102" roughly in my foggy alcohol effected memory, but has a large rear overhang, and is between a 40 and 80 in width of track.

    100" to 105" allows for a reasonable tailshft length, especially with more than 1 t/case etc too.
     
  4. hammerhead

    hammerhead

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    grog and shed - Thanks for the input. I am surprised, though, that this topic didn't get a bigger response after the heated debates I've witnessed elsewhere.
     
  5. woody

    woody unhelpful spotter Staff Member Admin

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    It also depends on the terrain you wheel...much over 100 around here and you are spending all yer time doing 10-point turns. Even reg-cab minitrucks are almost too long.

    I'm at 96 right now and it works well. Mine does not excel on steep uphills tho, which is where a longer wheelbase is truely needed. Next project will push me to 98....will see if that is the majic number or not.
     
  6. Medusa

    Medusa

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    My FJ45 truggy (real, not a converted 40 ) is at 106". Cutting brakes help with the turning problems.
     
  7. wngrog

    wngrog SILVER Star

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    [quote author=Medusa link=board=12;threadid=6376;start=msg59458#msg59458 date=1068080162]
    (real, not a converted 40 )
    [/quote]

    Nice jab.

    Oh well, sorry if the neighborhood is going downhill with my project. :-\
     
  8. CruisinGA

    CruisinGA

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    I've been wondering for a little while about cutting brakes....
    Are they like the brakes on dozers used to steer the dozer through slowing down one track? Is this why IIRC Smythe has dual M/C's on his erocc rig, so he has foot-operated cutting brakes? I doubt I'll be needed them anytime soon but I would like to know what you guys are talkin about.
     
  9. wngrog

    wngrog SILVER Star

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    That is exactly why Mike has the M/C setup that he does.

    YOu can do it with regular brakes.....most do it with line locks.

    One thing you really need to make it work is a transfer case that will let you select Front Low and Rear Low separately.

    I have an Atlas and I can knock out the rear and just hold my regular brakes. My engine will overide my front brakes and it works just fine.

    My next rear axle is going to have a hand brake that operates the rear brake to make the braking separate.

    I am sure it will make things easier on my system.

    Doing a "front dig" as it is called is VERY hard on your front axle components. That is one reason Mike kills so many birfs and inner axles.
     
  10. woody

    woody unhelpful spotter Staff Member Admin

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    Nolen and Bailey....uuuhhh....

    first, his dual masters are operated with one pedal, it's simply a nice system for non-booster braking with the Wilwood stuff. Does allow him better braking, but no ability to lock only front or rear...

    Also, cutting brakes are used on one wheel, either right rear or left rear, not on a front system or rear system. Easiest setup is with separate hand brakes and wheel-mounted e-brake setups. Eldorado calipers are good for this. Stock FJ40's with their t-case mounted e-brake are useless for this. Easy to lock up an entire rear is with a line lock, but locking only one rear allows for a better pivot around the inside tire.

    Finally, Smythe runs a Land Cruiser split t-case (and minitruck doubler), which cannot do FWD only and cannot to front digs. He has also run a welded rear diff for a few years (tho IIRC he has an ARB in right now) He's hard on his s*** cause competition forces it (and he doesn't back off obstacles) and because he takes some stupid/fun lines to see if they can be done.
     
  11. Medusa

    Medusa

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    My comment was not actually intended as a jab, and I am sorry you took it that way. To me, tech questions about Land Cruiser wheelbase are informed by knowledge of how the wheelbase came about (i.e., stock, stretched FJ40 or reduced FJ45). Why is that important?? It is important to me because all cruiser frames twist to varying degrees and the suspension performance is in a small way related to where the rear axle is located relative to the bends and crossmembers in the frame. To me a stretched wheelbase based on an FJ40 frame is different than a stock or reduced wheelbase on an FJ45 frame. (Tubed buggies are a different story) Since you, Nolen, introduced the term "FJ45 buggy" for the latest overhall of your FJ40 I think we are obliged to occasionally remind folks of the differences, even though they may be subtle.
     
  12. FJ60

    FJ60

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    my ribbing in other posts might have made Nolen a little gun shy :p

    I'm just here to keep things light hearted :flipoff2:

    Even though I hadn't taken the time to consider the differences... you speak the truth Medusa. So in the interest of the thread at hand which truck in your opinion (40 vs 45) of equal wheelbase has a better setup ???
     
  13. Medusa

    Medusa

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    I am not qualified to say that one is better than the other. They are are simply different and they will behave in slightly different ways depending on the details of the suspension.
     
  14. woody

    woody unhelpful spotter Staff Member Admin

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    IMO, given two equal wheelbase lengths, you now have to determine weight balance/bias, suspension design, spring rates, and a PILE of other things...and everything is situational. I know my truck absolutely works awesome for boulder crawling, but is less than perfect on steep uphills. I hope an added 2" in the rear will push the weight bias forward a bit, and combined with the added "power to ground" effect that a 4-link suspension has over a leaf sprung one will help as well.

    There is no perfect, just a series of compromises. And knowing those compromises and the drivers ability to work within them is what makes the rig successful.

    Given two otherwise identical setups, I would expect a long wheelbase FJ40 to perform marginally better than a identically wheelbased FJ45, simply because the weight bias of the 40 would allow improved uphill work. But, that same 40 may be poor on downhills, cambers, and boulders for the same reasons.
     
  15. wngrog

    wngrog SILVER Star

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    Weight bias?

    I have it set up now at 70/30 on flat ground. I have removed all the weight out of the rear except the axle itself and I really like it a lot.

    My rig climbs 100% better than it did when I origionally set it up with 100" WB and my light (compared to a 2F) LT-1.

    My new axle is going to be about 100# lighter than the RC D60, but I am going with a fuel cell that will be mounted in the middle......I am not sure how that will effect my climbing ability, should be marginal.

    My rig worked well at 100" with the weight shift to the front axle. I am looking at a 105-108" WB for the next rendition.

    I set the tub on the FJ-40 frame today and it is going to take MAJOR modifications to make it work. Also, the current plan of 105" may be too short to allow me room for a fuel cell, tire and cooler.

    Optimum wheelbase.......hmmmmmmm, wish I knew :D
     
  16. tclndcrz

    tclndcrz

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    woody you said you are going to do a 4 link suspension. Does the 4 link hold the truck in the air instead of the leaf springs or do you need coilovers or something like "that". If you do need something like "that" what will you use?

    Just curious. I looked in the suspension terms section and it said a 3 link does nothing to suspend the vehicle. Just wanted to know if its the same with a 4 link. I figure it is.
     
  17. CruisinGA

    CruisinGA

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    [quote author=tclndcrz link=board=12;threadid=6376;start=msg60064#msg60064 date=1068170407]Just curious. I looked in the suspension terms section and it said a 3 link does nothing to suspend the vehicle. Just wanted to know if its the same with a 4 link. I figure it is.
    [/quote]
    It is.
     
  18. woody

    woody unhelpful spotter Staff Member Admin

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    [quote author=tclndcrz link=board=12;threadid=6376;start=msg60064#msg60064 date=1068170407]
    woody you said you are going to do a 4 link suspension. Does the 4 link hold the truck in the air instead of the leaf springs or do you need coilovers or something like "that". If you do need something like "that" what will you use?

    Just curious. I looked in the suspension terms section and it said a 3 link does nothing to suspend the vehicle. Just wanted to know if its the same with a 4 link. I figure it is.
    [/quote]

    Correct, the 4 links will position the axle, 1/4 elliptical packs will support the weight. I've got the axle housing mostly done, the tabs on hand, the link rods done, some of the frame bracketry done, the spring packs cut/modded, and some of their mount bracketry designed.

    Got one more Attica trip coming, then it's unde the knife.

    Our next Attica trip will be an experiment of sorts on weight bias....I'm pulling my spare tire and carrier, pulling the doors, and (if the weather's decent) the windshield too. Leaving my spare parts box on the trailer, and seeing how well the rig works at the 3700-3800 range for total weight. y current rig bias is 52 front and 48 rear, and this outta shift that a little, maybe 56/44. Doesn't sound like much, but am curious on a few spots if the 5+% weight drop and bias change does anything.
     
  19. tclndcrz

    tclndcrz

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    thanks for the information and Ill look forward to seeing how everything works out.
     
  20. HZJ60 Guy

    HZJ60 Guy Tank Buster

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    101" to 104" is perfect for here in the Washington state area. Much longer than that and you start having sex with trees!




    TB