Lowest Leaf Sprung Wrangler

I don't have any belly clearance issues with my rig shown below.



At this ride height I still have 8" of up travel. Custom Deavers with bypasses all 4 corners.

Wanna race?

BenE said:

If you raise the DT 2”, then lower the whole rig down 2”, you have effectively put the drive train back in the same spot, and lowered everything else down around it.
How is that not, lowering your center of gravity (while keeping your belly height the same)?
Our sport is a game of inches, a lot of the time, so that small amount of clearance, and that small reduction in COG is a big deal, and worth it, to a lot of folks to gain.

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True. But the end result is not a lower COG....it's a flatter belly with the same COG....but maybe not even the same. Might still be worse. There are no numbers to support that lifting the drivetrain 2 inches and lowering the rig 2 equates to anything. It's better than not lowering it....but not a guarantee. You might gain belly, but the overall COG could actually be slightly worse. It's a trade off.

And it all depends on the rig. A rig running a d30 and d35 on 35's will have a different COG than the same rig on tons and 43x14.5's even if the belly is in the same spot. Heck, the rig on 43's might even have a better COG if the belly was higher just because of the added weight.

In my wheelin area, I have run into more belly clearance and diff clearance issues than anything else. I would like my new rig lower just simply because of looks but I just can't get it any lower. And if it were any lower, the rear tires would hit the body. At full flex I have less than 1 inch of clearance in the rear.

I am going through the "too low" thing right now.

14" SAWs on the front and SUA on stock CJ replacement springs on the back. I have about 5 inches of uptravel at ride height and it is super stable. I mounted whats left of the tub right to the frame, no actual "body mounts" and my seats are damn near on the floor. Im 6'3" and like headroom. Im also at 72" to the top of the cage with the 36's at 20 psi.

This summer


Last night


I wheeled it about 4 times and realized pretty quickly that I needed a flat belly. My COG was awesome but on 36's I was at like 16 to the bottom of the tcase :laughing:. I am now raising the motor, tranny, and tcase to get the bottom smooth and keep from constantly making repairs like this on the trail (oil pan)





When I was building it I kept having people tell me that I would hate not having a flat belly. I called bullshit and always responded with "like a few inches matter". Well it was big enough of a issue that I am pulling it all apart to raise it 3-4 inches. Who cares if Im super stable when I cant get over a fucking log to get TO the rocks I want to climb.

BenE said:

Listen to what you are saying. If the drive train stays in the same spot, and you lower everything else down (frame, body, cage, and all that heavy stuff), you are trying to convince me that the COG is somehow going to rise???
If you lower the weight (the weight is closer to the ground), you lower the COG, period.

I understand why you cant lower your rig any more (same reasons for all of us), but understand, if you did, you would also lower your COG.

I know you are a teacher, and probably way smarter than me, but what you are saying doesn’t make sense (at least not to my feeble brain).

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I agree with this ^^ completely.

Here is an approximation using some numbers that I think are fairly good representations of a lot of rigs (especially full body rigs NOT buggies)

Motor + Tranny + T-case = 450 + 175 + 100 = 725

Assume a rig with roll cage weighs about 3500 lb trail ready with a cage spare tire tools etc.

Disregard the weight of the axles and tires say 1250 lb (they are not moving for purposes of this discussion)

so... rig weight - axles and tires - drive train = body frame interior cage etc.
3500 -1250 -725 = 1525 lb

So you move the drive train 725 lb up 2" into the body and frame and then lower the body and frame and drive train or 1525lb +725 lb down 2". This means that you still move 1525(down)+725(back down)-725(up) =1525 lb down two inches and effectively lower your center of gravity.

Say you raised your drive train up 4" and then dropped the body and frame 2" that would mean that 725 lb was still 2" above its original position and 1525lb went down 2" from its original position. So you still lowered your moved a total of 1525(down)-725(up) = 800 lb down 2" and effectively lower your center of gravity.

It all depends on what the components that make up your rig weigh.

MuddyPaws said:

I can't find the right words to explain it. I am not claiming to be smarter than anyone though. But going on rough "total mass" numbers is just wrong. You might be moving the whole 1525 down 2 inches, but where is the COG in that 1525? Is a large chunk of it high from the cage, seats, top and tools? Might be, depends on the rig Then you move that 750 from the drivetrain into that zone and it "may"...."could"....negatively alter COG.

Like others have said....it really depends on the rig and the components.

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I won't claim to be smarter than anyone either. I learn something new every day!

What you said is very important.

Its a little more complicated than this but...
The center of gravity or center of mass of an object is basically the average location of its mass. This can be loosely translated to the CG will be near the heaviest portion of an object.

And so, its a little more complicated than this but...
The center of gravity of a jeep (or any object) will be the average location of the centers of gravity of its components.

So as we said it depends on the rig and its components but...

Unless someone is packing fat chicks on top of their roll cage or bricks in their frame the CG of a body, frame, roll cage will likely be somewhere below the dash or near the firewall of the tub.

And the CG of a drive train will likely be around the center of the transmission bell housing.

Average the two and you will have a CG that is generally estimated to be near the top of the transmission bell housing

Because your body, frame, and cage is heavier moving it 2" will have a greater effect on CG than moving you drive train 2".

The distance an object is moved will also change its affect on CG. So you don't want to raise the drive train any more than you have to because moving a light object a great distance could have the same effect on CG as moving a heavy object a small distance.

So as long as the body, frame, and roll cage significantly out weigh the drive train and the builder lowers the body, frame, roll cage, and drive train after raising the initial raising of the drive train the rigs center of gravity should still be lower. Unless the drive train was moved up far greater than the body, frame, and roll cages moves down.

Break over angle VS COG


LWB rigs especially low ones have thier draw backs and strengths its like anything its all a compromise tailored to the driver and their style/preferences.


Im 98"+ on my wheel base. i was SOA and 22" to the bottom of my belly pan on flat springs with 35's. I went back to SUA and was at 19.5" to belly pan, at the same time that i went SUA i lifted the engine 3/4" and the tranny 2" to yeild a flat belly. I never had a high centering problem with my old setup i did have a teetering issue since my change back to sua i can point to multiple repeated situations where i used to lift, teeter and occassionally tip that i now walk through...... there are alot more factors but the end result has been what i sought.

When considering height axle width, tire height all of these factors create triangles that center and point to the COG. its is not as simple as saying you raised the engine yet dropped the frame and body and ultimately canceled out. the frame and body are wider and carry more leverage than the lifting of the motor and tranny. plus the frame and body are the transfer's of the suspended weight to the suspension. lowering the body and frame widens the leverage placed on teh roll over angle. lifting the enigne may raise weight above and effect the roll over angle but has less effect because it is a lower percentage of the weight, it is centered between teh larger mass and it is not applying the leverage, the frame/body are which dictates the roll over angle (obviously considering equal axle widths).

If lowering the frame and body while raising the engine was such a bad idea why have so many comp rigs applied this philosophy with success.



Muddypaws makes some good points do not discount them.


But there were some other good points . someone pointed out that if the engine tranny and tcase is moved up 2" all of that weight is moved up. only a portion of the weight is higher, the balance of that weight remanins still centered and loaded onto the frame and the frame's orientation dictates the side loading, leverage and ultimately the roll over angle.


this doesnt even come close, this guy doesnt even factor in frame width or leverage but heres a spot to begin http://www.jeepaholics.com/tech/cog/


Good debate there are pluses both ways and minus's



According to CAT scales I'm +/- 4800 lbs ont he tires depending on trip and the top im running


Dusty on poison spyder small obsticle - YouTube

dusty rookie filter prichett canyon utah 2012 - YouTube

I haven't been around on here much lately but this is where I'm going with my YJ. I had plans of it having built 60's, linked front and rear and all of that good stuff but then I realized now is the time to buy a house and I'm in the middle of doing that now.

Anyways I'm only on 35's and I have been running SUA forever on it with 3.5" BDS springs. They have now settled to about 1.5" over the last 8 years. I'm only going to run a 2" BDS spring SUA and keep running my 35's with some more trimming of the tub and high lining the front fenders. This is more of a dual purpose street legal rig but for my use, which unfortunately has shifted to more street driving than trail time, I think it will serve me well. I did swap in a 5.3, 4L60 and Atlas and tucked it up nicely but I don't think I'm going to go back and make it absolutely flat just because I need to have a flat belly. A lot of it comes down to what you want out of the rig and the terrain you wheel on. I only go to Rausch Creek since it's the closest to my area and would rather focus on my line and driving ability than running 47's and just walking over everything. That's no fun. I know I'm not hardcore on 35's and whatnot but it's a fine line to walk and you need to find that right balance between being low and stable and stupid low and dragging over everything.

Now that my Jeep is on 40s I will throw in some more numbers.

It is a garage ornament for now until I finish the CJ-10.



40 inch competition Maxxis Creepy Crawlers on 17x9 Trailready double beadlocks.

74" to the top of the cage, 22" to the bottom of the skid.

I took this thing all over Moab on 35s and did not have a single problem ever with breakover angles, COG or articulation. It sits low, the center of mass is low, and the skid is pretty high in relation, flat against the frame.

Leaf spring rigs are a different beast than link suspensions, and need a different driving style. They do not articulate well, no matter what your ramp measurements say. They spend a lot of time carrying tires over things, lockers are an absolute for a leaf sprung rig driven hard.

My rig is light for a leaf sprung truck, last weight was 3800 with driver before the skid plates, probably now weighs just under 4000 without driver.

Watch the tires on Golden Crack. I forgot to engage the front axle and drove across in 2wd, which is a testament to how well this rig drives, but tires to not drop and the whole rig just kind of floats across. Much different than a link suspension, where the tire would have dropped in the crack and then crawled back out.

Gavan crossing Golden Crack - Moab, UT - YouTube

If my rig had a higher center of gravity, that tipping action would have certifiably sucked. As it was, it was just another little obstacle. Not a big deal at all.

It look like it has a high center of gravity, but all the heavy stuff is mounted low in the chassis.



It has a 101 inch wheel base and a flat skid. It loved the shelves and dropoffs in Moab. I stopped here for a photo, I just let the clutch out and it popped right up. No drama, no hitting the skid, and even if I did, there would be no damage, it is all a flat piece of 1/4 inch steel.



BUT, this is just about all it articulates. Just about any linked rig would be at about half travel here, but I was barely touching the ground on either side. I went everywhere the linked guys did, just with some more dramatic carrying of the suspension and many more 3 wheeled moments:flipoff2:



I guess my experience, summed up, is:

Lower it as much as you can
Raise the drivetrain just as much as you need to to make a flat skid
Mount everything heavy as low as you can
Enjoy the look of fear on your linked buddies face as you go everywhere they do... on three wheels!