Can you give me the Uhaul wheelbase and the length of it's rear overhang from the center of the rear wheels? I'll try and do the calculations for raising the front.
Can you give me the Uhaul wheelbase and the length of it's rear overhang from the center of the rear wheels? I'll try and do the calculations for raising the front.
SKJSS (formerly Klayfish) said:For E36 M3s and giggles, I did a rough mock up. This is on relatively flat ground. The board is 8' long. Maybe a 10' ramp + truck nose in the air will do the trick. Presuming I won't get high centered as it gets on the truck.
That angle will definitely high center when the car hits the deck.
You will have to raise the front wheels of the car, the front wheels of the truck, or build a longer ramp.
You can do a similar practical measurement... measure the low point of your rockers, make 2 blocks the same height, set them on the ramp and the truck bed the same distance apart as the wheel centers of the Miata, and pull a string across the blocks.
I'm still intrigued by the 13ft Uhaul center ramps that can hold 1,000lbs.
Imagine if you will something perhaps made of wood to act like Race Ramps to initiate the loading angle:
So, the 13ft ramps are not actually set on the ground. 13ft plus another 6 ft would get you 18ft. Since I have concerns of the uhaul ramp being strong enough then I also imagine a wood or metal wedge that will do generally what these are doing in this picture:
The entry ramps (wood) and the mid supports (metal or wood) could be stored/strapped somewhere on the flatbed. The 13ft ramps could benefit from a U-shaped holders that would allow them to be stored and strapped similar to this ramp truck.
Furthermore, load with a winch so there is no "acceleration forces" added to the ramps. The winch should load slow and steady. To really be cool as hell, get a winch that is remote controled so you can walk to the rear of the car while loading to be sure of no errors.
All of this though is not really quick or easy setup/teardown.
Here's a workflow:
Just did a few measurements on a similar truck:
Wheelbase 256"
Tail overhang 9'-6"
Deck height 35"
Tire diameter 33"
The bottom of the bumper is 16" lower than the floor
So, the rear overhang is 44% of the wheelbase. That means if you raise the front wheels 8", the rear will only drop about 3 1/2". I know it was my idea, but it doesn't feel like that's a great solution for the limited gain. Too risky trying to lift that heavy front end enough to make a difference.
If the deck is 35" and you want to maintain a 15% grade on the ramp, it will need to be 233" long (19.4'). If your ramp is 10' long, it will a 29% grade.
Another problem... The wheel tubs are 6" tall, and there is only 46" between them. You will have to raise the car an additional 6" to get over the tubs- they are 88" from the rear door.
One more thing... ramp storage. The existing stowed ramp is about 8' long and 2'7" wide. It's stowed position (with required framing) is about 6" thick. Obviously the center ramp won't work (shame), but there isn't space on the 2 side to stow a similar ramp under the floor. There is only 6" clearance from the tires to the bottom of the wheel tubs (with no load). You wouldn't be able to stow 2 similar ramps on each side- they would interfere with the wheels.
So your best option may be to stow 2 narrower ramps in the existing center pocket, slide them out entirely and manually lift them in place for the wheel tracks. Maybe the existing ramp could be cut in half and modified. It's 8' long (which means it would be steep- 36%), but the ramp is rated for 2750 lbs (which would be enough), and you may be able to pull it up with a winch (heck, movers can roll a piano up it).
BTW, I also looked at the connection between the floor and the frame of the truck. Tilting the existing floor would require significant fabrication.
I think you are gonna have to spend some money on fabrication regardless.
Best option would be narrow ramps stowed in the existing ramp storage pocket, and air bags on the rear axle to drop the bumper to the ground, plus a winch.
OMFSM ... Trigonometry was invented 2300 years ago. No need to cave man the math. I'll try once given the measurements that apply to the truck in question.
I don't know how long your travel trailer is, but a 37' tow rig is gonna be tough to maneuver in campgrounds (if you do that)
The measurements you want for a 26ft Uhaul should be here: https://www.uhaul.com/Truck-Rentals/26ft-Moving-Truck/
In reply to Stampie :
It's called "taking a practical measurement". Just like his pic with the MR2. It's not a crime if he's more comfortable with a practical measurement than trig- it's done every day.
Lots of excellent fabricators never had a trig class.
In reply to John Welsh :
Thanks. That gives me everything except the rear overhang so that I can calculate how much the ramp attachment point lowers.
Edit - and wheelbase
SV reX said:I don't know how long your travel trailer is, but a 37' tow rig is gonna be tough to maneuver in campgrounds (if you do that)
I co-drove this to the Challenge in I think 2018.
I parked it nose-to-nose with a typical sleeper cab semi. We are not that much shorter than the semi! That is an 20ft enclosed trailer. This should be the similar length of a 26ft Uhaul box truck and 20 ft travel trailer. It is rather cumbersome in tight areas.
Speaking of tight areas...and this may apply to OP as well...this rig was gas not diesel. Let me tell you how this sucks. Imagine a typical truck stop like Flying J or Petro, etc. The big rigs pull around back where the driveways and lanes are wide to the diesel pumps. The cars go to the front of the building. There is no gas in the back, just diesel. That means that even though we are the size of a semi rig we are going up front with the cars. We need two pumps worth of space to get up to the pump. This assures that you will be waiting for the car ahead of you to be done before you can pull up to actually get fuel.
In this picture we have just arrived and needed bathroom quickly so we went to the back for the parking size we require and went in. After bathroom and food we will still be headed back to the front of the building to fight for a gas pump. In short, fuel/food stops are not quick.
In reply to SKJSS (formerly Klayfish) :
Double check that deck height. I know you said 32", but that tail overhang can screw with you on slightly unlevel surfaces.
All the UHaul specs say 35" (including the diagram John linked). The truck I measured was also 35".
Most accurate way to measure is probably in front of the rear wheels, not at the rear edge.
Good luck!
In reply to John Welsh :
I noticed the same when we got our enclosed trailer. There was a lot of extra "swing" on the trailer. I think the enclosed trailers have the axles further back. We were in the Suburban so was still able to do normal gas stations with extra care. I still feel bad for volunteering you for that trip to the Challenge.
My image looks like a Ford. His could be a GM. I suppose a couple inches are possible. I know UHauls pride themselves on a lower deck height.
The yellow is probably loading dock height which is 48"
I measured a 26' GMC UHaul.
Dont feel bad volunteering me. Being a SuperC based off a Kodiak and not just a C based off a van, that thing towed like a dream. 8.1L and Allison for the win. It didn't need diesel to be a capable hauler. It wasn't until you had to negotiate the actual fuel pumps that diesel would have been prefered.
In reply to John Welsh :
I agree. I've driven a lot of 26' UHauls, and I've towed my 26' enclosed trailer several times behind one. It gets to be a LOONG rig (but the truck is a capable tow vehicle)
SV reX said:Just did a few measurements on a similar truck:
Wheelbase 256"
Tail overhang 9'-6"
Deck height 35"
Tire diameter 33"
Yes, these numbers are correct. The truck is a 2008 GMC C5500 with the 8.1L and Allison.
I bought a 5500lb winch with synthetic rope and remote control.
In reply to SKJSS (formerly Klayfish) :
What's your budget on this? Some of our suggestions are a little pricey.
Did you get a screaming deal on the truck?
Its much more truck than you need, and the deck height creates challenges.
The bed is almost twice as long as you need, and the capacity it about 5X what you will need. The consumables (tires, brakes, etc) are gonna be more on that truck than a ramp truck.
It CAN be done, but it becomes a question of price.
I'm $6700 all in. It is more truck than I need, but we want to do other things with it in addition to carrying the car.
If I put the front of the truck on this, it should make the job easier, I presume. Hydraulic ramps
Those rear wheel humps are sturdy as E36 M3. Trying to remove them and cover them with plate
In reply to SKJSS (formerly Klayfish) :
The rear suspension won't have any movement if you remove those wheel tubs.
SKJSS (formerly Klayfish) said:SV reX said:Just did a few measurements on a similar truck:
Wheelbase 256"
Tail overhang 9'-6"
Deck height 35"
Tire diameter 33"
Yes, these numbers are correct. The truck is a 2008 GMC C5500 with the 8.1L and Allison.
I bought a 5500lb winch with synthetic rope and remote control.
I'll try and use those numbers and figure out how much the front needs to go up. I'm assuming a 10 foot ramp is the goal. I was surprised that you can get them when I looked earlier this evening but you're looking at $800-$1200 just for ramps.
SV reX said:In reply to SKJSS (formerly Klayfish) :
The rear suspension won't have any movement if you remove those wheel tubs.
No worries, they're sturdy as hell and are firmly resisting all attempts to remove them anyway 
Starting off with the quoted numbers above.
With a wheelbase of 256 inches by raising the front wheels 8 inches you only change the angle 1.79 degrees. That 1.79 degrees lowers the rear attachment point by 3.56 inches. Let's round off to the attachment point height being 31.5 inches tall. While looking at things last night the problem isn't the angle of approach. It's the high center. The high center angle for a Miata is 11.52 degrees. Add our tilt of 1.79 degrees and we get a ramp angle of 13.31 degrees. That ramp angle with a attachment point height of 31.5 inches gives us ramps 137 inches long. Now SKJSS stated that his deck height was 32 inches instead of the 35 quoted above. That would get an attachment height of 28.5 inches and then a ramp of 124 inches which is right at the 10 foot ramp desired. As you can see anything that can be done to lower that rear attachment point helps a lot.
My thought is a redeck from the rear of the wheel wells back. If you make that a dovetail of 10 degrees it gets your new attachment point 20 inches lower. If the tubs are 6 inches that gives you a deck height of 41 inches and a rear attachment height of 21 inches without having to raise the front. At that point 10 foot ramps gives you 10.1 degrees and 8 foot ramps give you 12.6 degrees. This allows you to pull up put on some ramps and unload without having to screw around raising things and wondering if you are being safe.
My extra special Christmas thought is make that new rear overhang hinged at the front. Put a simple hand operated jack to raise the rear of it. Then as long is your angle of approach is over 10/12 degrees you can get a very low car up on the rear overhang, jack it up, and have a total flat bed that you never have to worry about high centering.
Anyone want to check my numbers?
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