JK 4 door + 37s = new driveshaft(s)?
02-15-2007, 07:07 AM
#31
JK Newbie
Thread Starter
Join Date: Nov 2006
Posts: 4
Likes: 0
Received 0 Likes
on
0 Posts
I bought my Jeep to go "OFF-roading!" It is not a daily driver for me. So I am building it to stand up to anything. Im sure you can drive your Jeep back and forth to work and not have a problem with the stock drive shafts. All the experts that make the lifts say any lift over 4" require driveline modifications. Its not coming from me. So I believe the right answer is yes... you do need it. I didn't throw any words around. I did the upgrade because the people that designed my lift told me I would need it! It is similar to the TJ when it was required to use a slip yoke eliminator. Bottom line it is required by the lift companies. Call them and ask them. Ive done far more research than most on this forum. My knowledge is coming from me... its from the people who build this stuff for a living and they are damn good at it. I agree there are differences in some of the mods on a 2dr verses a 4dr. You sound like a smart guy. I know im not. You'll figure it out...see you on the trail... maybe! 
Anyways, the point of the thread was to find out the difference between "required" and "recommended" - the two words that are always tossed about, but never explicitly defined. For 2-door JKs, it sounds like everyone says new driveshafts are required for lifts of 4" or more. This seems to be a consensus born out of experience, and not just a sales pitch. For 4-door JKs, the answer has been less clear. The stock 'shaft with no lift must be fairly good - I've seen (and heard the crunch from) people doing stuff on rocks that I wouldn't do no matter what. I pretty much drove off the lot straight off-road to show off my JK to the in-laws - it's the easiest way to get to their house (and used to be the easiest excuse not to go visit!
)Yep, I expect to be on road just as much as off, if I choose to drive the JK when I get up in the morning. Eventually, I'll probably end up justifying all of the upgrades people are doing. It's just nice to hear if people aren't having problems right off the bat with 4" lifts and stock 'shafts. If this thread was filled with "Danger!! You will be the only noob on the trail like this" comments, then I would say thanks for that info too.
If you're in MI, I'm sure you'll see me and the JK covered in mud, somewhere
-a2kl
02-15-2007, 08:09 AM
#32
JK Enthusiast
Join Date: Sep 2006
Location: Quebec city, Canada
Posts: 186
Likes: 0
Received 0 Likes
on
0 Posts
From what I understand, on Unlimited, 4'' of lift didn't require any driveline mods to be driven on the road as there is not vibration due to the CV.
It's an other question if hard wheeling is intented. Then I will go with Evolution and say yes, you need better driveshaft just like any other 4by as there is no manufacturer that will overbuild a vehicule. They have a hard time doing $$$ and they cut on everything (just look at the hood try to fly when a 18 wheeler pass).
I think that is what we all have to know.
If someone can only put those driveshaft on a test versus other one that we know, then we will be sure of their strenght.
As for upgraded Birfield, it's been over 10 years that they try to mahke it better and better, that's probably why they have so great result. If someone take the same time on Jk'ones, then this will be a way to go.
Wish it help
It's an other question if hard wheeling is intented. Then I will go with Evolution and say yes, you need better driveshaft just like any other 4by as there is no manufacturer that will overbuild a vehicule. They have a hard time doing $$$ and they cut on everything (just look at the hood try to fly when a 18 wheeler pass).
I think that is what we all have to know.
If someone can only put those driveshaft on a test versus other one that we know, then we will be sure of their strenght.
As for upgraded Birfield, it's been over 10 years that they try to mahke it better and better, that's probably why they have so great result. If someone take the same time on Jk'ones, then this will be a way to go.
Wish it help
02-15-2007, 06:31 PM
#33
JK Super Freak
CV vs u-joint
Been an engineer for some time. Not sure where these comments are coming from but here is what I can tell you. CV joints are strong. In fact, they are stronger than U-joints. CV joints can provide a greater range of mobility than a U-Joint without vibrations. While u-joints may look beefier, they are only as strong as the tear-out cross section which in fact is very small. Look at the hole where the u-joint is located. You can see how thin its at that point. While the load is one forth at that point, its still the weak point and is governed the shear max for that material. CV joints have a solid shaft that is significantly thicker. While they are still governed by shear max... there is more opportunity to expand the diameter, hence increasing its strength.
That being said, I cannot tell you how strong how strong of a load either one can handle with out looking at their specs. But, what I can say is that don't underestimate the strength of that CV drive shaft. Considering that DC beefed but the U-joints on the front axle, I would bet that the driveshaft is stronger than most of giving it credit for.
That being said, I cannot tell you how strong how strong of a load either one can handle with out looking at their specs. But, what I can say is that don't underestimate the strength of that CV drive shaft. Considering that DC beefed but the U-joints on the front axle, I would bet that the driveshaft is stronger than most of giving it credit for.