4x4 Conversion

[toyfunraider]

I currently own a 1992 21' Sunrader motorhome. I'm also looking into the purchase of a 1979 Toyota motorhome that is also two wheel drive. My question is: What would it take to convert a 2x4 to a 4x4 short of replacing the entire truck chassis ?

[nolan]

My question is: What would it take to convert a 2x4 to a 4x4 short of replacing the entire truck chassis ?

That depends on your mechanical ability I guess, The easiest would be to jack up the camper and slide a 4x4 truck under it. Or you could cut the existing frame in half and graft the 4x4 front section on, then spend countless hours fabricating, and wrenching to mate the 2wd cab to the new 4x4 front section, little things like brake plumbing, steering, wiring, floor clearance, body mounts, bumper mounts, switching the rear axle to 4x4 configuration, E brake hookups, more than likely depending on the length, stretching the frame, then building driveshafts to fit, ect.ect.ect., Or you could start with a stripped 2wd frame and fab all your own spring mounts, steering mounts, crossmembers, followed by the items above.

I,ve done all three and each has its own obstacles to deal with, but depending on what your wanting in a finished product dictates what kind of time and effort you put into it.

[ColoradoMtnJeeper]

I have a 4x4 Sunrader, and have come to the following conclusions, you don't need to connect the front wheels to the engine. If you just lift your vehicle by adding leaf springs in the rear, and depending what year you have, either installing heavy duty torsion bars or adding more leaf springs. then you need a transfer case or a add on under drive unit, for your low range. If you use a transfer case, you wont need a front driveshaft. I have gone up some pretty tough 4x4 jeep trails, and have left the front hubs unlocked, and never had a traction problem. There is so much weight on the rear wheels, and hardly any on the front, the front being connected to the engine doesn't really help. The places I have been, I don't think anyone with a motor home would want to take theirs up the same trails. There are times when one of the front wheels will come off the ground 3 feet going up some of these trails. The most extreme jeep trail a motor home can go up is limited, and because of this using rear wheel drive is totally sufficient.

[turtle]

I have a 4x4 Sunrader, and have come to the following conclusions, you don't need to connect the front wheels to the engine. If you just lift your vehicle by adding leaf springs in the rear, and depending what year you have, either installing heavy duty torsion bars or adding more leaf springs...... The most extreme jeep trail a motor home can go up is limited, and because of this using rear wheel drive is totally sufficient.

The best reason I could see for 4x4 on a motor home (outside of the "kool factor") is to help get out of a "sticky" position. When I brought the Sunrader back from California I went across the Navajo Indian reservation from Page AZ to Gallup MN. I made the mistake of pulling off of the narrow road onto what I though was a solid pull off. It turned out to be extremely fine and soft sand and the coach immediately sank up to the frame and came to a very sudden stop (sort of like hitting a run away truck emergency ramp). Luckily it was on a slight grade and I was able to back up and get a running start and "plow" my way back onto pavement, engine wide open in low, and several attempts. Locking front hubs would have made this a little easier (and a lot less stressful).

[Gulfstream Greg]

I have a 4x4 Sunrader, and have come to the following conclusions, you don't need to connect the front wheels to the engine. If you just lift your vehicle by adding leaf springs in the rear, and depending what year you have, either installing heavy duty torsion bars or adding more leaf springs. then you need a transfer case or a add on under drive unit, for your low range. If you use a transfer case, you wont need a front driveshaft. I have gone up some pretty tough 4x4 jeep trails, and have left the front hubs unlocked, and never had a traction problem. There is so much weight on the rear wheels, and hardly any on the front, the front being connected to the engine doesn't really help. The places I have been, I don't think anyone with a motor home would want to take theirs up the same trails. There are times when one of the front wheels will come off the ground 3 feet going up some of these trails. The most extreme jeep trail a motor home can go up is limited, and because of this using rear wheel drive is totally sufficient.

Having a 4x4 Sunrader myself and having driven through mud and some rather ruff stuff I would say that I am glad I have 4x4. I would have not made it out in the mud. The other point about 4x4 is that having the front wheels supply some traction takes considerable load off of the rear axles. My Sunrader weighs in at around 6800 pounds fully loaded. Sure I can probably make it up that steep rutted with big rocks incline using just the low gears in the transfer case but why? I would much prefer that the front wheels help do some of the pulling.

[nolan]

I have a 4x4 Sunrader, and have come to the following conclusions, you don't need to connect the front wheels to the engine.

but why? I would much prefer that the front wheels help do some of the pulling.

My thoughts too Greg, kinda defeats the purpose to me, sorta like installing a 1 ton floater dual axle then running a single tire,

[Gulfstream Greg]

My other 4X4, 1971 Bronco. I would never do the same type of offroading in the Sunrader as the Bronco but I also will not hesitate on getting out and locking in the front wheels and putting it in 4X4. It really does take a bunch of strain off the rear axle and drive line. There is another thing to consider in a 4X4 versus 2X4, the transfer case. Those lower gears are a wonderful thing at 8000 feet elevation with a 7000 pound machine starting from a dead stop uphill. Just the fact that with 4X4 and lower gears allows you to crawl through some rally nasty stuff makes a huge difference. Unfortunately the Sunrader has an auto trans. Having driven 4x4's for the last 35 years both auto and stick I will take the stick any day. But I have an auto. Sigh

[ColoradoMtnJeeper]

Greg, I have a 87 4x4 Sunrader with 39,000 miles, I have a 5 speed stick shift and have been 4 wheeling for over 40 years living in Colorado all of my life. I have 2 Jeeps, both with dual ARB lockers, too much stuff to list. I will take an automatic any day over a stick shift for 4 wheeling, an automatic is almost like cheating. The ability to apply torque gently, and being able to stop and take off without spinning your tires when your going up a 35 degree slope with loose dirt far outweighs the braking ability of a stick shift going down hill. If you would like to swap your automatic for my stick, I would be interested if your automatic has an overdrive and a lock up torque converter.

Dave high in the Rockies

[Gulfstream Greg]

Hi Dave

I see your points. Its been awhile since I did any wheelin with an auto other than the Sunrader. I can't exactly put my finger on why I prefer the stick over the auto, it might be the feeling of control. I put a NP435 4 speed in my Bronco and have been really happy with it. I have heard a lot of folks say they prefer the auto over the stick for offroading. I have no idea if I would like a stick over an auto in the Sunrader. I really don't do the extreme as in the Bronco but here is a situation where having the auto made me aware that I could get in a situation that I might not get out of. We were at about 7000 feet and I had maneuvered down to a lake edge. I got situated and then started the leveling process. The blocks in the rear were those leggo type plastic ones stacked two high which is around 4 inches. Not a problem for 4x4 in low gear to climb onto. I put the blocks behind the wheels and attempted to back onto them. To my surprise I was unable to develop enough horsepower to get up on the block. Part of the problem is in the turbo engine. The auto trans, the higher gearing of reverse and 7000 pounds would not allow enough engine rpms to get a spin on the turbo to really produce any power at 7000 feet. It was as if there was a governor on the engine. So I re situated the truck and pulled forward onto the blocks with no problem. If I had been in the same situation with a stick I could have feathered the clutch a bit and got the rpms up. Certainly not good for the clutch. Would I have had the same problem with a non turbo 22r or V6, maybe not. At some point in the future I hope to replace the stock turbo with one of the available hybrids that will spin up faster at lower rpms, when I get rich.

All that said here is a huge advantage with this auto and transfer case setup. At high altitudes I can start out in 2x4 low range on hills etc. and shift into high range after getting up some speed. That's a huge safety advantage when pulling out onto a highway. The transfer case behind my trans is the chain type which allows for shifting between low and high and in and out of 4x4 at speeds up to 50 mph. I really like that part. I also think the auto is probably far better for the engine as far as wear is concerned as there is far less lugging of the engine as apposed to a stick.

Thanks for the offer of swapping tranys but I think I will keep the one I have. And yes it does have a locking torque converter and overdrive. I have to get ready for work but will post back later with the advantages of having overdrive with this transmission.

[Gulfstream Greg]

OK so here is a huge good point about Over Drive with this (A340F) transmission. I believe I have a A340F transmission and VF2A chain drive transfer case. What I have found with overdrive is that it can actually cool down the transmission rapidly. I noticed this one day while going down the freeway running a 220 degree plus temp in the transmission. I took it up to 60 mph and dropped it into OD and literally watched the temp needle fall down to 160 degrees, in seconds, and it stayed there even after switching out of OD. I could not believe my eyes. Knowing this I started doing some testing. I found that I had to be doing at least 60 mph or faster for it to work. Any slower and there would be no change in temp. Question is does the A340H behind the V6's also do the same thing?

[86rader]

greg, i don't understand the temp situation you have. i could see it dropping a bit due to increased airflow through the cooler, but, not the huge drop you are seeing. there is one possibility. maybe the tranny's thermostat never opens at lower speeds? Getting it over 60 might just raise the temp enough to open the thermostat and bring the cooler into the mix. 220 seems like a pretty high temp for this. You might wanna have that looked at.

[Gulfstream Greg]

There is a thermostat in the tranny? Learn something every day! I had no idea, where would I find it to replace it?