4 wheel steering question

[amc75matador]

Ok, bear with me on this. I was thinking of building a dump truck to go in the woods for firewood and was tossing around the idea of 4WS. If I start with a late 70s chero with Q-trac, and take a front rear from a 80's Wag and place it out back on the Chero, the offset should get close to work for the driveshaft and I could make the steering work with hydraulics, as I will have a hyd pump for the dump body anyway.

My question is, will the gears work or will they be under bind running in reverse rotation? Considering trucks back up and all, this could work. Anybody have any experience with it? I don't think it would ever see speeds over 20MPH.
thanks

[AlsChopShop]

what was that movie, american graffiti? were the cop car gets the axle torn out from underneath. you'd get the same effect, without having to tie the axle down!:thumbsup:

Al

[BRUTUS]

Ok, bear with me on this. I was thinking of building a dump truck to go in the woods for firewood and was tossing around the idea of 4WS. If I start with a late 70s chero with Q-trac, and take a front rear from a 80's Wag and place it out back on the Chero, the offset should get close to work for the driveshaft and I could make the steering work with hydraulics, as I will have a hyd pump for the dump body anyway.

My question is, will the gears work or will they be under bind running in reverse rotation? Considering trucks back up and all, this could work. Anybody have any experience with it? I don't think it would ever see speeds over 20MPH.
thanks

I am sure you would have to get reverse cut gears for the REAR axle. They won't bind! Also, you realize that rear steer is not DOT approved for highway use.

I would recommend getting MUCH heavier springs for the rear at least to haul lumber. If you are running a dump bed... you will probably need to run a hydraulic reservior and possibly a secondary hydraulic pump. Depending on what cylinder you have to run your dump bed and rear steer... the reservoir needs to be at least large enough to hold fluid for both cylinders when they are both compressed (hydraulic fluid empty)

You probably will have to add lots of beef to the frame to support a dump bed.

I would say that 4 wheel disks would be mandatory considering the weight and terrain involved.

You might want to check the frame width in the rear to make sure that the tires don't hit the frame when they turn. Might have to custom fab some frame stuff to clear.

I am not a QT guy so I don't know of the top of my head how much rear offset the QT has but I would definately check and double check what the drivetrain angles would be in the rear. When you have u-joints at a complex angle... the u-joint angle is easy to exceed.

Hope this helps and be sure to post pictures of the buildup... I will keep an eye on it! :thumbsup:

Any reason you wouldn't start with a J-20? What size lumber would you haul? Poles? Firewood?

[scotty]

the front and rear gearsets in FSJ 44s are both standard cut. it doesnt matter if you run them in the front,or the rear. if you turn a front axle 180* around from the front,it is still driving the drive side of the gear,its not running backwards,and it WONT be trying to go the opposite way as the front.

in theory,running a front axle in the rear works just fine.

in reality,here are the prollems that you will have:

-the rear frame rail width is too wide,youll need to prolly mount springs underneath,or on the inside of the rails to get springs to line up with somewhere that you can put perches on the front axles tubes.
-itty bitty dana 44 sized pinion and 297x sized wheel joints trying to live under a heavy dump bed,especially with a big load in it :eek:
-the aforementioned prollems of mounting the dump bed onto a cherokee frame

not knocking the idea of a 4ws dump truck,just dont do it with dana 44s. youll need yo use axles that can handle the weight and the strain of what youre planning to use it for(rockwells would be my personal choice ;) )

further questions? :)

[Boghog1]

what about using the Quadsteer rear axle out of a newr chevy truck?

http://en.wikipedia.org/wiki/Quadrasteer

Since it is found in 2500 series it should be a reasonably beefier axle. the downside is the cost, but I did a quick search on car-part.com and found one with 4.10 gears for 1800 in TX and 2 others in 3.73

Using a centered diff would not be a problem even if you used the BW tcase

[orangecherokee]

the front and rear gearsets in FSJ 44s are both standard cut. it doesnt matter if you run them in the front,or the rear. if you turn a front axle 180* around from the front,it is still driving the drive side of the gear,its not running backwards,and it WONT be trying to go the opposite way as the front.

WINNER!

Not knocking you BRUTUS but that's always the answer from someone. If it makes you feel any better I almost got slapped for saying that out loud in front of some buddies one time. :p I didn't hear the end of it for awhile needless to say.

[BRUTUS]

WINNER!

Not knocking you BRUTUS but that's always the answer from someone. If it makes you feel any better I almost got slapped for saying that out loud in front of some buddies one time. :p I didn't hear the end of it for awhile needless to say.

No worries. I always forget that the transfer case changes the direction of the front output with respect to the rear.

I didn't even catch that he want's to use D44's. Bad idea as Scotty mentioned.

[AlsChopShop]

No worries. I always forget that the transfer case changes the direction of the front output with respect to the rear.

I didn't even catch that he want's to use D44's. Bad idea as Scotty mentioned.i'm guilty too! woops! :eek:

Al

[amc75matador]

Thanks for the replies, I'm still confused on the rotation deal. I've tried to figure it out on paper, make a drawing of a rear end and rotation arrows, then turn the paper 180 and the arrows are obviously going the wrong way. What am I missing?

I would be carrying only firewood, on my own property. The only reason I would do it with a Chero is because I own a few of them already. It would a small dump bed. I currently use a chero and small utility trailer (4x6). The problem with this setup it emptying the wood out. It'd be easier if I could just dump it.
My idea of 4ws came because there are a lot of obstacles when going up for wood and I find myself often backing up to clear something, not the best position to be in with a trailer and also when loaded with firewood going downhill.
Truck would only be used offroad. I have a plow truck now that I only use for plwing and firewood. So that would be my start.

[scotty]

make a drawing of a rear end and rotation arrows, then turn the paper 180 and the arrows are obviously going the wrong way. What am I missing?

you are quite simply missing the fact that during forward motion,the front axle,flipped around to the rear,is not turning the same way as your arrows :)

lay under the rear of your truck,behind the rear axle,looking forward toward the front. both yokes are turning the same way from your perspective at the rear. however,if both are turning clockwise,the rear one is turning clockwise,but you are viewing it from the rear,so while its spinning the same direction,and spinning the axlesahfts in the same rotation(and thus providing forward motion),if you moved around to the front and viewed it from a different perspective,its actually turing counter-clockwise,and is spinning the innards alittle differently.

due to this difference,a standard cut gearset used in the rear is using the pinion to drive the "drive" or flat side of the teeth on the ring gear.

now you take a standard cut gearset and move it to the front. both yokes are spinning the same direction from your perspective at the rear of the truck,but the front gearset is now using the curved or "coast" side of the tooth to spin the ring gear,since its orientation is 180* different from the rear gearset.

this is in fact how high pinion,"reverse cut" gearsets came to be. driving the ring gear with the coast side of the tooth is the weaker side of the tooth,and makes the assembly not as strong as it would be to drive it with the drive side of the tooth. the high pinion diffs gearset is backwards so the pinion can spin the ring gear using the drive side of the tooth,as it should .the high pinion is simply a result of this differently cut gearset,wich works to our advantage in addition to being stronger,also helps with driveshaft and pinion angles. a win-win situation :thumbsup:

"reverse rotation" is a misleading,downright incorrect term accidently spread by people who didnt understand how the reverse cut diff works. a high pinion front diff spins just the same as any other front diff,its gearset is simply redesigned to be stronger in that particular application(front axle).

people have since started using high pinion diffs in the rear of short wheelbase rigs,such as cj5s,to help with the angle of a rediculously short rear driveshaft compounded by lift and/or longer than stock transmissions. while it does help with the angles,a reverse cut gearset in the rear has the same prollem as a standard cut gear up front-the pinion is using the coast side of the tooth to propell the rig down the road. better drivesahft angles,weaker gearset.win-win?not exactly. ;) unlike a reverse cut gearset up front,a reverse cut gearset in the rear is a tradeoff.

there you have it,in a nutshell. :eek:

further questions? :)

[amc75matador]

Scotty, thanks for taking the time to explain it, my confussion laid on the driveshaft rotation.

[AlsChopShop]

one output on your transfer case spins clockwise, the other is counter-clockwise. that way if you flip it, the t-case is changing the direction it spins to the axle, thus making it go the correct way. :)

Al

[scotty]

one output on your transfer case spins clockwise, the other is counter-clockwise. that way if you flip it, the t-case is changing the direction it spins to the axle, thus making it go the correct way. :)

Al

well,sorta.

again,from your position on the ground,behind the rear axle,looking forward at the t case, both outputs will be spinning the same direction. either both of them toward the passenger side(clockwise) or both of them towrard the driver side(counter clockwise).

lets say for the sake of argument that the both yokes are spinning toward the passenger side. from the rear of the truck view,both yokes are spinning clockwise,tho you are technically viewing the front yoke from behind.

heres where it gets alittle tricky. if you get up and walk around to the front of the truck,and look past the front axle toward the rear,the front yoke is (still) spinning toward the passenger side. however,from your new point of perspective,that yoke is now spinning counter clockwise. :eek:

to me,to say that the transfer case "is changing the direction it spins the axle" sounds like you mean that one yoke spins toward the passenger side,while the other spins the opposite way,toward the driver side. this is not true.

to say that one yoke spins counterclockwise,and the other spins clockwise,when viewing each of them from their fronts,is a correct statement,but it is not really correct to say they are spinning "opposite directions",since they are in fact both spinning the same when viewed from the same reference point.

i hope that makes sense :p

[AlsChopShop]

to say that one yoke spins counterclockwise,and the other spins clockwise,when viewing each of them from their fronts,is a correct statement,but it is not really correct to say they are spinning "opposite directions",since they are in fact both spinning the same when viewed from the same reference point.

i hope that makes sense :p yes, i should have mentioned that was if you are looking at them from the fronts. its the only way i knew how to describe. thanks for clearin me up! :thumbsup:

Al