sye using front shaft

[proskier101]

do you have a FWD option on your transfer case? i know mine doesn't. my vehicle was designed to only have the front receive torque when the rear is also receiving torque. that tells me the front was not designed to get 100% of the engine torque. why would they overbuild it to do so when that could never normally happen? i don't know if the 50% figure is exactly accurate, but it's certainly going to be less than the full shot.

i have run mine in FWD, i broke a transfercase output shaft at the bottom of a pit and had to flog the jeep balls to the wall in FWD(4 LOW!) to get up a hill....didnt break a drive shaft...i also got in a car accident about a week ago and had to drive about 30 miles in FWD..no issues...

im not too sure but i think the joints on a front and rear driveshaft are the same...i may be wrong but i think the only difference is the THICKER tubing and smaaler diameter.

numbers may be numbers but what people have ran and used is proven

 

[Yucca-Man]

With the front DS in the back whats the maximum lift I can run ?

Around 5" is where the driveshaft begins to look too long, but that also depends on the rear axle. I've got a D44 in mine, and if I remember correctly that pinion sits a bit higher and farther forward than the C8.25 or D35. I'm sure someone relishes the opportunity to correct me on that, but the higher/longer pinion yoke means the driveshaft will work with that axle and a slightly taller lift.

Jim www.yuccaman.com

 

[proskier101]

Around 5" is where the driveshaft begins to look too long, but that also depends on the rear axle. I've got a D44 in mine, and if I remember correctly that pinion sits a bit higher and farther forward than the C8.25 or D35. I'm sure someone relishes the opportunity to correct me on that, but the higher/longer pinion yoke means the driveshaft will work with that axle and a slightly taller lift.

Jim www.yuccaman.com

you are correct it is longer..amybe 1-2" IIRC as i have said. i have 8" lift and run a stock front XJ drive shaft from and auto late 80s XJ...but the yoke is extended quite a bit.

 

[SOUTHTEXASXJ]

wow some good info here I am getting ready to doa hack an tap on my as soon as I finish my y-link

 

[xjtrailrider]

i have run mine in FWD, i broke a transfercase output shaft at the bottom of a pit and had to flog the jeep balls to the wall in FWD(4 LOW!) to get up a hill....didnt break a drive shaft...i also got in a car accident about a week ago and had to drive about 30 miles in FWD..no issues...

im not too sure but i think the joints on a front and rear driveshaft are the same...i may be wrong but i think the only difference is the THICKER tubing and smaaler diameter.

numbers may be numbers but what people have ran and used is proven

They are the same U-joints

 

[Georgia Mike]

so you think that just because something doesn't break, that means it can't have any negative effects on other components? wow thanks for that very thorough analysis there, you must be an engineer.

....but the thing you don't seem to be understanding is that the driveshaft can and will affect other parts of the driveline, and people may not even realize the true cause. like someone might be eating up ujoints more often than is normal, or the pinion bearings might be going, but they attribute that to some other problem.

Yeah, it's called setting the pinion angle to address the type of driveshaft you're running.



You said it yourself. People are running them with no issues. People have been doing it for YEARS with no issues. There's nothing to analize. I am just failing to understand why you want to come on here and argue about something that has been PROVEN to work with no issues?? It's a freakin' driveshaft. They are balanced, they use the same u-joints. What can it possibly do to create negative effects on other parts?


No, I'm no engineer, but I have what is called COMMON SENSE, and you sound more like the "engineers" where I work that want to overanalize things to death to prove their point at all costs, only to fail to do so in the end when a much simpler and easier method is shown to work better, or at least just as well as their over-engineered method.

My advice to you:
Go buy a Tom Woods shaft. It will cost you about 300% more to go that route. It will be "proven" by your standards. It will be pretty and shiny. It will come wrapped up nice and tidy in a package. Will THAT will prove to you that it's "engineered" to your specifications? And it will still be the same basic design, so if an XJ shaft will cause "negative effects", so will a TW shaft.

The ONLY thing I can think of that a TW shaft would have over an XJ shaft is longer splines in the slip, and possibly larger spline section. But it's been, yet again, proven that u-joints will fail long before the XJ shaft's spline section will.

According to your logic, you shouldn't do ANYTHING that will have an adverse effect on other parts of the vehicle. So save yourself the headache and leave your XJ stock.

It's funny, but you are starting to remind me a little of "XJGuy" that used to post on here. Even in the face of defeat, he would argue his point 'till he was blue in the face about things that had been proven time and time again to work (or not work), yet he couldn't get away from his computer long enough to get out there and actually SEE what did or didn't work.

:doh:

 

[2xtreme]

If you want to calculate the torque capability of the front and rear shafts (to compare the two) it really isn't all that difficult. I have not looked up the calculation to post here but it would be easy to find and basically it just has to do with the diameter of the tube and the wall thickness (assume both materials are the same). Then you can calculate the two in comparison to one another.

Keep in mind that both U-joints would fail well before either tube would, but it would give you at least a warm fuzzy about the comparison of each to one another.

Michael

 

[proskier101]

They are the same U-joints

Thank you..so strength wise you get a thicker tubing, same Ujoints, and i guess you could say less wind resistance due to the smaller diameter:doh:

 

[Georgia Mike]

Here's one for $200

Don't know if it will work for your application, but it's a start:

http://www.naxja.org/forum/showthread.php?t=952337

 

[xjbcca]

I run two front shats in my dd w/ 9", about 15 000 km now.. um 10 000 miles?
It will work without mod till 6" of lift, then you should legthen it.
I havn't had any problems (on or off road)
that said...
I have other plans on my "list" and have always thought of this as "temporary"... but we all know how vauge that term is.

 

[copbait]

...
It's funny, but you are starting to remind me a little of "XJGuy" that used to post on here. Even in the face of defeat, he would argue his point 'till he was blue in the face about things that had been proven time and time again to work (or not work), yet he couldn't get away from his computer long enough to get out there and actually SEE what did or didn't work.

Not really, actually you guys are doing a good job of convincing me that my reservations about doing this may be unfounded. I had thought there was some sort of a science behind drive shafts, and that the information was probably out there but just not readily available. It looks like it may not be as big a deal as I had thought.

I do have a few emails out to some of the people in the business who can be considered "authorities" on the subject, but I'm not hopeful in hearing back from them. If someone's testing has shown the front shaft to hold up just as well as one of their custom shafts, I can't imagine them rushing to get that information out to the public.

Thanks for the replies so far, I may just go ahead and grab one and pop it in and not worry about it.

 

[Ramsey]

I don't know, I'm not sure I would trust the dozens of people that have and are currently running this setup that told you it works fine, I bet they are just out to get ya.


Quit thinking about it and just do it, or if it bothers you that much cough up the 250-300$ for a custom shaft.

 

[Dave41079]

You could always do this.

 

[2xtreme]

I had thought there was some sort of a science behind drive shafts

There is a science behind it. Read post #47.
As an engineer we design things around all sorts of criteria. In order to design a shaft to handle a specific torque you would us a "science" to calculate how big the shaft needs to be to handle the torque. Having said that, the week point in any driveshaft is the U-joint and not the shaft itself.

I run a front shaft in both front and rear of my XJ like many others. I think that a specific rear driveshaft designed for the aplication would be better in some ways (maybe even stronger?) but the criteria for my Jeep is matching front and rear shafts so that my 1 spare works in both places and to keep the parts inexpensive and easy to replace. It has worked for me and many other for a long time without any issues. I am also certain that there is no issues with other components on my Jeep due to running a small front shaft in the rear application

There is a science to it.
But don't get hung up on the science when you don't need to. :cheers:


Michael

 

[xjtrailrider]

Thank you..so strength wise you get a thicker tubing, same Ujoints, and i guess you could say less wind resistance due to the smaller diameter:doh:

More rock clearance, not as easy to dent

When I ordered my TW shaft I talked with the man himself. He builds shafts 2 ways, larger diameter/thinner wall for better street performance and balance or thicker wall/smaller diameter for off road use(harder to balance but harder to dent as well).

 

[BlueCuda]

Mine is a decent example of why it works. I built a stroker for it about 3 years ago, my jeep is much heavier than stock, and i run a larger heavier tire than stock. I have an SYE and use a front driveshaft in the rear.

The following picture shows me putting 100% power through the rear driveline which was formerly a front driveline. And yes I was on rock and not dirt lol. IIRC this was 2wd High, 2nd gear, about 4500RPM.

The results of this testing were less tread and hot rear brakes .

But after reading that the front shaft can only take 50% of the power makes me afraid to put my jeep in gear!!! lol

 

[copbait]

..

But after reading that the front shaft can only take 50% of the power makes me afraid to put my jeep in gear!!!

heh, i said the "front end" was only designed for half the torque, but wasn't sure about individual parts like the drive shaft.

if you think the front drive line as a whole is as strong as the rear, do me a favor remove your rear drive shaft and do the same test in 4HI and let me know how that turns out

 

[proskier101]

heh, i said the "front end" was only designed for half the torque, but wasn't sure about individual parts like the drive shaft.

if you think the front drive line as a whole is as strong as the rear, do me a favor remove your rear drive shaft and do the same test in 4HI and let me know how that turns out

like i said here??

i have run mine in FWD, i broke a transfercase output shaft at the bottom of a pit and had to flog the jeep balls to the wall in FWD(4 LOW!) to get up a hill....didnt break a drive shaft...i also got in a car accident about a week ago and had to drive about 30 miles in FWD..no issues...

im not too sure but i think the joints on a front and rear driveshaft are the same...i may be wrong but i think the only difference is the THICKER tubing and smaaler diameter.

numbers may be numbers but what people have ran and used is proven

hasta

 

[BlueCuda]

I don't think the front drivetrain is as strong as the rear, the front shaft is what was in question wasn't it? Behind all the smoke there is a stock 200K mile front driveshaft turning the pinion on that 8.8.

I would try it with the front but I would have to strap it to something, its hard enough to overcome the discs on the rear and do a burnout, getting past the front brakes would be tough LOL. But like Chris mentioned above I have seen people beat on a FWD only cherokee bad trying to get it off of the trail and never had a problem.

 

[proskier101]

I don't think the front drivetrain is as strong as the rear,

like a 30 vs dana 35?? lol off topic but..normally yes front isnt as strong..but the drive shaft is