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extending wheel base

four_by_ken

four_by_ken

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How far is too far. This thread on Pirate had me asking this question.
http://www.pirate4x4.com/forum/showthread.php?t=310717&page=1&pp=25
By swapping in the longer springs in the front and rear, we can gain 4-5 inches at both axle. So, a conservative 8 inches gained.

Does this make a differance?
Would you like to go further?

Just trying to start up some conversation on the subject.
 
Wheelbase is a double edged sword.... Sometimes it really helps to be long/sometimes it helps to be short.

I really like my 110" wb.

My buddy DJ's rig has wound up ~120".
619225_52_full.jpg

Most of the time it helps him - but I have seen at least 2 occasions where it has hurt.

:dunno: ...who knows what's ideal - guess it depends on your personal preference.

Marv
 
the longer wheel base will help approach and departure angles but then again it hurts break over angles so you have to find the length that works best for the terrain, driving style, etc...
 
I understand the extremes... just kind of wondering what the K5 crew has found with this issue.

Because when I do some spring swapping, there are differant options I can do as far as only a couple inches gained in wheelbase to nearly a foot.
 
I think mine is around 114 right now, and I like it fairly well as a compromise. Sometimes a longer wheel base makes all the diff. I got spanked on a waterfall in Los Cruces where my wheel base seemed to be just a tad short to make the climb. Another truck about 4"(?) longer was the only truck of the crew to make the climb. Was it suspension, wheel base, or skill that made the diff? <shrug> It was also driven by a 16 year old girl! :blush: Shoudna said that...

I have a friend with a Ford that is (IIRC) 132" long. Climbs like a billy goat and works well all around. But he has pure grief sometimes making turns. I think he invented the 12 point turn. Break-over can sometimes be an issue too, but somehow he always seems to make it on over without major grief. <shrug> Again, how much is wheel base and how much is other things working right?

And there is no necessary correlation between wheel base and approach angles. All other things being the same, the longer wheel base will provide better approach/departure, but there is a limit to what you can do with leafs. In fact, the long leaf setups used for larger travel flexy suspensions are going to guarantee that there is a point where you can't improve your A/D angles any further.
 
I dont have anything to add about how to shorten up the overhang on a leaf sprung vehicles, but I would like to make mention of my current wheel base plans, aside from agreeing that you should do what fits your tire size and terrain.

I'm running ~44" tires with a 130" wheel base, but this winter I'm going back to 122". I was 117 on 38's which worked good, then I went to 122 when I did the rear 4 link. It worked good. Then I went to 130 when I did the front radius arms so I could clear the cab better. 130 worked good as well, but I would like to improve my break over angle some, although it has never actually prevented me from completing an obstacle.

So, its my opinion, that 120 - 125 is about ideal for ~7" of lift, and ~44" tall tires.

Sorry, I couldnt help but post a picture. The back of the bed will be 61" from the back of the cab, and will provide a vertical departure angle with the 122" wb. :D
 
This isnt "super tech" but its something to consider when going to a long wheel base.

Make a flat skid, and make it tough. A good portion of the obstacles that will cause problems with break over angle, can be completed with some momentum. If your undercarrage isnt protected, and smooth, using momentum to bounce over things isnt going to be an attractive plan.

I've been lucky so far, but the clocked 205 has definately helped.
 
alaska fabshop said:
Make a flat skid, and make it tough. A good portion of the obstacles that will cause problems with break over angle, can be completed with some momentum. If your undercarrage isnt protected, and smooth, using momentum to bounce over things isnt going to be an attractive plan.
Click to expand...
I think bouncing over things is cool sometimes, thats why we have V8s and big axles, is to use them.
Does the full belly skid plate retain alot of heat under the rig ?
 
I've wheeled my longbox truck for a couple years. The wheelbase is something that can be worked around when it's a bad thing. You can pick some lines a 96" Jeep can't even imagine.

It's the approach and departure angles that are the problem. All the rear overhang is a f'n nightmare. You always have to watch the box after the tire and you're always dragging butt.

In my opinion, 9.5'-11' of wheelbase is about right. Longer than 11' is too long. Shorter than 9' is too short. A shortbox Chevy is about perfect.

On the K5 I moved the front spring hanger 6.5" forward. With 56" springs that means the front axle is going to go about 4.5" forward. In the rear I'd like to move the axle as far back as the 63" springs would allow but the gas tank limits me to about 3". That'll give me a wheelbase somewhere around 114"/9.5'.

With 40" rubber I'll have about 6" of frame sticking out past the tires in the front. I figure I'll have a little more than a foot in the rear. I can't ask for too much more out of leaf springs.
 
I currently have 133" wheelbase and the ONLY reason I am going to a diffrent wheelbase on my newest project is to gain more seats for the kids. I am stretching it for as much as I can. I like the stubliity of the longer wheelbase and my truck was only too long on a few obsticals. It has been more help than not in most places. I am building a 79' k5 with as much wheelbase as I can. I will post up the total wheelbase after this weekend. If you talk to most Heep owners they are streching there wheelbases too because >>>>>>>>>>>>>>>>
>>>>>>>>>>>>>wheelbase rules>>>>>>>>>>>>>>>>>>>>:D
 
Well, I did some measuring today. The maximum wheelbase I can run is 118". Moving the front axle forward 4.5" and the rear axle rearward 7". 106.5" + 4.5" + 7" = 118". I'm not sure if I'm going to move the rear axle that far rearward or not. If I do move it that far rearward I'll have 17" of frame hanging out past the tires.
 
Please don't flame me, but could someone tell this redneck where to measure wheelbase from. Axle center to axle center or outside tire to tire. Sorry.
 
Wheelbase is measured from center of hub to center of hub. Track width is the measurement from outside of tire to outside of tire.
 
Well right now I have a 114" wheelbase and I like it alot. I feel it is a good compromise in wheelbase vs. breakover clearance. I run 40" tires now and I think the next set will be 42's. Like most people say build a good bellypan you will definately hit it.
 
I think that wheelbase is generally your friend. I do agree with the statement that it should be proportional to your tire size though. A 130" wheelbase is no good with 30" tires.

My wheelbase is stretched to 119.5". I did this for better stability when hill climbing or climbing ledges as well as the go-fast stuff. I also did this because I decided to use a 42" tire. The tire size makes the break-over angle manageable. My approach and departure angles are truly beautiful now compared to what they were before. The gas tank had to be relocated which with the price now of generic aluminum fuel cells at around the $150 mark isn't that big of a deal.

As mentioned the wheelbase thing can suck when the trails get tight but with twin sticking becoming almost commonplace now just add some cutting brakes and you can maneuver again. Hell if you can afford it do like I'm planning and add rear steer to your set-up. You will have the wheelbase for any obstacle and the ability to steer through whatever comes your way when the trail gets tight.

A good formula to use that I feel works well is Wheelbase = Tire Size x 3

Using this formula you come up with a 35"-36" tire being about perfect for a stock k5. I have run that set-up and found that it worked great. Add bigger tires, extend the wheelbase.

Just my .02 :D

~Max
 
one problem with the flat bellypan...chevy's aren't anywhere near flat underneath, the damn t-case hangs down about 6 inches below the tranny mount. I'm working on making a new skidplate design that is beefier then what i offer now. It is essentially a flat bellpan with a dropped section for the t-case. Not that i've had any problems with any skidplates i've sold, ust thought i'd add some t-case protection.

I run a 104.5" wheelbase but i also only run 37-38.5" tall tires and between 2.5-4" of suspension (with a 3" body lift). I like haveing as much turning radius as possible. i think anything under 100" is too short, and over 115 is too long (just my opinion which is probably wrong...haha).

Obviously there are exceptions to every rule. The numbers I just threw up are for the more conservative wheeler, not the 44" tired group. If you have a mud truck then wheelbase is good, if you live in washington wher trees are EVERYWHERE then your should probably be in a flatfender :-P
 
i run ~110" and 39.5s now. oncce the front springs are in it will be around 112" and next set of tires will be 42's
 
I'll be extending my wheelbase on my blazer from 112" to 120". 6" forward and 2" back. The stuff we wheel the most is Big rocks. moonrocks and all the other canyons around NV. the occasional trip to the CON' and fordyce. My buddy Dave is running 126"wb on his yota with 25" belly height and 42's. that thing GETs IT!. So IMO wheelbase is personal preference and your rig should be built around the terrain you wheel the most.
 
With the 56s front and rear I should be right around 114.5" or so. What length is best will depend on the obstacle... sometimes lots of wheelbase rocks (ledges, nasty climbs, nasty descents also)... other times short wheelbases kick ass (curvy/narrow/tight trails etc).

As far as departure/approach angles go, with 44s I oughta be getting close to 90 front and rear. I chopped off the frame about 2.5" behind the shackle flip brackets, and that is the lowest part of the rig in the back. Don't think it will be a problem. With the whole thing being tube, it'll be no problem getting a tire on something to help get up/over because the thing will taper down to the width of the frame in the front/rear.

j
 
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