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Discussion Starter · #1 ·
I have been lifting my jeep slowly over the last 6 monthes. I got a 2inch body , 1 inch shakle and soon to install 2 inch add a leafs. I have really not any trouble with anytihng but the other day my buddy was saying somthing about the angle of my drive shaft might be screwed up?? I also have heard a story of a front drive shaft slipping out ? So do i need to lower my trany or do any modifications or will i be alright??

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92 Jeep YJ with 1 inch shackle lift and a 2 inch body lift running 31's

[This message has been edited by Brent (edited October 09, 2001).]
 

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Superfly
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Originally posted by Brent:
I have been lifting my jeep slowly over the last 6 monthes. I got a 2inch body , 1 inch shakle and soon to install 2 inch add a leafs. I have really not any trouble with anytihng but the other day my buddy was saying somthing about the angle of my drive shaft might be screwed up?? I also have heard a story of a front drive shaft slipping out ? So do i need to lower my trany or do any modifications or will i be alright??
You will probably need to put some shims in there to make sure your pinion angle is still somewhat parallel to your tcase output angle. A slightly longer rear driveshaft would also be a good idea. The front is probably still ok for now.

Of course, the only way to tell for sure is to ramp both sides of your Jeep and see if anything binds or pulls out.

...lars


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Discussion Starter · #3 ·
so i should be alright with those add a leafs also???

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92 Jeep YJ with 1 inch shackle lift and a 2 inch body lift running 31's
 
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I'm running that exact lift right now. I have yet to have the rear driveshaft fall out but I do get a nasty bump and shake when I hit the gas hard. I haven't lowered my t-case either.


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High Country Explorers
Red YJ 4" lift
"I hope that was the skidplate"
www.members.home.net/ichris4x4/index
 

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Discussion Starter · #5 ·
Hey ichris4x4

I was just woundering what size tires u run and do u have trouble with those shackles hitting rocks?

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92 Jeep YJ with 1 inch shackle lift and a 2 inch body lift running 31's
 

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LOOOOOOOOONG POST!
but pretty comprehensive....
read it slowly if your name is brent
i'm trying to teach you almost everything I know (not that i know everything)
it's a lot to take in at once

**************

think about it this way

scenario (1) is before lift
senario (2) is after lift



you see the springs or shackles push the axle away from the jeep allowing for bigger tires but inadvertantly cause driveline problems.
you can see the angle on the drive shaft in scenario 2 is much greater (obvious exagreation but you get the point). This is very hard on the u-joints which attach the transfer case to the drive shaft and drive shaft to the rear diff (pinion).
this causes u joint failure
no biggie
they are a $14 part but if left unattended the problems can get expensive (i am proof of this).

To solve this people do a few things.
the most cheap and popular of which is lowering the center crossmember (skidplate) that the t-case is attached to by putting spacers between it and the frame rails. this helps with one side of the angle
but the angle on the rear diff is still too extreme.
that is why someone suggested 'shims'. shims are wedges that are placed between the spring and the spring perch on the axle to tilt the axle pinion to point upwards thus relieving some of the stress.

chrysler threw another monkey wrench into the works by designing the rear driveshaft very awkardly....
now,
think about it this way
your suspension moves
in essence, your axle moves up and down
so there has to be some give somewhere in the drivetrain. THE DRIVESHAFT!
you would think the driveshaft would have some sort of telescoping mechanism to absorb the ups and downs....
wrong
chrysler decided to make our lives harder and put the telescoping part (slip yoke) on the very end of the shaft.....
the driveshaft moves in and out of the t-case on the ups and downs
this means, if you go too far down the dirveshaft can pull right outta the t-case
this would explain the dropping your driveshaft comment.
have a look under there
you'll see the shiny part right at the end of the t-case
thats where it bobs in and out.

lemme just say here and now you will prolly never have to worry about your front driveshaft. The fact that it is so long means it's not as affected by the lifts...and besides....this driveshaft is telescoping!

Now
with my set up
quite similar to yours
1.25" shackles
2" aal's
1" body lift
and 33's (rarely have problems with the shackles hitting things)

The 1" body lift was actually a side effect of the 1" motor mounts i did. I did 1" motor mounts to correct the angle on my driveshaft.
I could not see lowering the t-case...this would defeat the purpose of lifting the jeep in the first place.
so think about it, lift the engine does the same as lowerign the t-case....it points the t-case down to achieve closer to stock angles but instead we are working with the other end. Going up instead of down.
this definately worked ($$$) in my case but only cured the t-case end of the driveshaft. I had not shimmed the rear axle yet and this is where i ran into problems...
i ended up exploding my t-case because of neglect
keep this in mind
don't do it half assed
use your whole ass!
do it right the first time.

Now after all that there is still another way to go about curing this problem and that is what i have done seeing as i needed to replace a buncha parts already in recent weeks.
there is somethign called a slip yoke eliminator (SYE) kit for your t-case (NP231). Including work and the new rear drivshaft you will need made this can cost over $1000 easily. Lucky for me i found a smokin deal from a super nice guy named chris siebert on this board and i got the whole deal (t-case, sye, and new rear driveshaft for $400!).
this kit changes the case's main shaft with a stronger unit and makes the t-case output 'fixed'. you are then able to swap in a telescoping driveshaft. this also cuts 4-5" off the length of the t-case making the anlges less severe.
to understand how longer driveshaft lessenes the angle take a pencil and hold it straight...
now drop one end of it down an inch
now do the same with a yard stick
the angles at either on both sticks are quite different.
the driveshaft is also a 'cv' shaft meaning it has one extra u-joint in there
makes the angles a little less steep aswell.
here's mine

have a look under yours to see how it differs

this may also come in handy
it shows the legth of the slip yoke
the shiny silver part on the bottom shaft
use it as a reference to see how much of yours is actually showing and how much you have left
more than likely your suspension will incur less than an inch of total travel on the dirveline so you should be fine



this can be easily checked
park one tire on a rock and 'max out' your suspension and see if it's close to pulling out
take some measurements
simple stuff

I'm gonna include this pic too
just for educational purposes...


this is a shot of my jeep missing the t-case
here you can see the front driveshaft not attached
it shows the u-joint pretty clearly
it's that thing that looks like a '+'
the 'slip' or telescoping part is not at the t-case on this shaft...it is further down closer to the front of the jeep. You do not have to worry about this shaft 'slipping out'.

sorry about the length but now you should know everything there is to know about the subject. It always helps to be informed.

that's about all i can think to tell you
am i missing anything?
anyone?

good luck
RJ

[edit - hey lars...feel free to add this to the YJ FAQ

Thsi was a lot of typing
if you take the time to read it please respond so i know my time wasn't wasted]

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1992 YJ with 33's

[This message has been edited by RYJAY (edited October 10, 2001).]
 

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OMG!
Ya know, I think I had to read that in shifts of 10 mins each.
Did the shims work out for ya, RyJ? What were they worth? Made out of Al, or steel...?

Now, for height:
If the vehicle continues to "grow" with time (lifts etc) and longer driveshafts are needed (as per Lars suggestion), when does the need for a track bar setup become a necassity? I know of a few Jeeps that SUFFER from chronic cases of axle wrap.

Hey, wait a minute....this isn't the Toyota board???


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Keith (aka RedApe)
82 Toy
http://www.island4x4.com
Victoria BC
 

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thanks keither!
damn yota guys!


shims are worth...
well, i think i got raped.
I paid $10 each for some really crappy aluminum ones from vic spring
they look like real trouble but i just got them in a week or so ago so we'll have to wait and see.

as for trac bars
they are stock on yj's but long since have ripped mine out.
the need for a trac bar in a sua YJ is minimal...they hinder a resposible driver offroad more than they would help on road.
but when jeepers start getting into custom stuff like 3/4 eliptical and soa and such the need greatly increases.
there are many different anti-wrap bars available
I personally have no experience in this area so am unable to comment.

in both brent's and my cases the aal's add a rigidy to our packs which help combat axle wrap and leaf springs do double duty locating the axles horizontally under YJ's so there is no need to worry there.

RJ

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1992 YJ with 33's

[This message has been edited by RYJAY (edited October 10, 2001).]
 

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Discussion Starter · #9 ·
RYJAY - thanks for all that info! I defentley look into that.


usually when i ask a question i get a sentence answer but u really helped me out thanks again

It was not a waist of time at ALL!!!

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92 Jeep YJ with 1 inch shackle lift and a 2 inch body lift running 31's

[This message has been edited by Brent (edited October 10, 2001).]
 

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Superfly
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Nice post, RJRAY. <g>

As far as track bars go, I'd just like to clarify that the track bar's primary responsibility is to maintain the axle's lateral position under the Jeep. In other words, it makes sure the axle doesn't shift to the right or left by very much.

An anti-wrap bar, in contrast, is tasked with controlling the axle wrap, or the amount that the pinion will _rotate_ up and down around the axis that is described by the axle shafts. Or, more simply, it limits axle housing rotation. To a small degree, the track bar does this but, IMO, it is only a small side effect of its design. And, as you've mentioned, it will hinder suspension articulation.

...lars

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RJRAY
i have a question for you about the motor mounts. you say that they raise your engine higher and then tilt your rear output lower towards your pinion right. now think of a stock jeep - the t-case is actually a little tilted towards the rear making the u joint for the front driveshaft at more of an angle (front output on t-case is pointed up a little). so my question for you is by added the engine lift didn't you increase the angle of the front driveshaft u-joint at the t-case. i am not sure about you but under full droop my yoke on the front driveshaft hits the yoke on the t-case. (could be fixed by a grinder but that would involve removing the t-case. you might want to check this out by ramping your jeep and then taking off your front drive shaft and checking to see if there is any evidence of yokes hitting each other. you will be able to see the grease marks. just a little food for thought.

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'93 sahara ~ rancho springs, SOA, EB axles, detroit, 35s, and hi steer in the works
 

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if anyone is interested in the 1" mm's
I got the from www.mountainoffroad.com
I strongly suggest the more expensive 'torsion rubber' ones because I have heard many horror stories about the poly ones transmitting all the engine vibes to the frame.

also...
there is a write up back on island4x4.com http://island4x4.com/4x4tech/body/morebodylift/index.html

the mm's could be fabricated easily enough for much cheaper but since i don't have the required skills i was willing to fork out the cash
MORE is a great company and provides exceptional customer service.
all emails were returned within 24 hours

with the mm lift alone is still did get some vibes and managed to crap out atleast 3-4 ujoints (on my rear pinion...uncorrected) before 'the incident'
you can see all the spewage in that one pick on the underside of my jeep from 'the incident'


RJ

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1992 YJ with 33's
 

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good info ryjay,i'll be doing a 6" lift
soon so this info will be most helpfull in
the near future.
info and knowledge are never a waste of time!

cheers; eric


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2muchfun
1998 jeep cherokee 4.0l
stock but tries hard
 

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thanks guys

norcpeejer and sarl - IT'S RYJAY!

heheh

as for your statement cornjeeper...
yah it would tilt the front up a bit but i haven't noticed any ill effects
this could only bring the sgaft further away from the skid plate (is that what you mean?)
i don't have problesm rubbing on the skidplate but i do have smash up against my exhaust the odd time but it's cuz it's already so mangled and bent up



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1992 YJ with 33's
 

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Originally posted by RYJAY:
i don't have problesm rubbing on the skidplate but i do have smash up against my exhaust
i don't mean the skid plate i am meaning the yoke on the top of your front driveshaft hitting the yoke on the t-case. (ie binding) the angle can only be so large before the yokes start hitting each other. it happens to me!!!!!
can anyone make this a little clearer for him......anyone else with the same problem?


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'93 sahara ~ rancho springs, SOA, EB axles, detroit, 35s, and hi steer in the works
 

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Discussion Starter · #16 ·
hey lars

I think u should add this to the YJ FAQ. It seems like alot of wheelers need this info.

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92 Jeep YJ with 1 inch shackle lift and a 2 inch body lift running 31's
 

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Originally posted by Brent:
hey lars

I think u should add this to the YJ FAQ. It seems like alot of wheelers need this info.

I second that motion. RYJAY, I'm standing at my computer applauding. (well, not really. But in my heart I am
). I was going to ask what a SYE does/is but I now know. Definately NOT a waste of time.

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Play hard + Rest easy
Drive a Jeep--'92 YJ
Option...Black Nite

[This message has been edited by OptBlackNite (edited October 10, 2001).]
 

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Wow!
thanks guys
it's just good to know i can write something that is understandable.

cornjeeper
sorry, i think i know wht you mean now
I suppose i could run down and check it out but i'm too lazy right now...
I didn't notice any signs of metal on metal contact when i had it all apart but i wasn't looking either.

thanks for the heads up

RJ

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1992 YJ with 33's
 

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Hey RYJAY, Do you know or have you measured the length of the stock slip yoke (the shinny silver part)
Actually, if you still have your stock shaft sitting around and you have nothing better to do, would you mind doing a quick measure for me?
Reason I asked is that, I'm running 4.5" of lift with the 1" T-case drop and the shims that came with the springs,I'm just wondering how much slip yoke is left in the T-case. I can see a good inch and a half or so sticking out. I'll probably put steeper degree shims on next week.
I guess I just want to know how long the stock shaft will hold up for until I have dollars for an SYE.
Thanks

P.S. I'm just looking for reassurance.

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90 XJ traded it for
91 YJ stolen, replaced with
92 YJ
 

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sorry dude
I actually sold my stock shaft to cover the cost of shortening the new one.
if only an inch and a half is sticking out you should be fine.
unless you have some kinda super high travel set-up more than likely your suspension will only inflict about an inch or so ot travel on your slip yoke.
prolly not more than an inch and a half for sure....
that's 3/4" one way and 3/4" the other
I'm sure there is atleast 2 1/4" of slip in the yoke.
you should be fine but this is all just speculation.
it is best to test it yourself and know for sure.
go find something to flex on or next time you go wheeling take some tools (a socket the size of the bolts on the rear pinion strap) and try to max out your suspension. Then simply have a look to see if it pulled out.
it's easy enough to unbolt the rear pinion straps that hold the u-joint in there and just slide it back in then bolt them back up again.

sorry i can't be of any real help but if i had to guess i'd say the slip yoke was between 2 1/2" - 4" long.
(yah that's a lot but it's just a rough guess...it's prolly closer to 4").

maybe someone else will know for sure or have the stock shaft lyin around...
I'll send a message to the guy who i sold my shaft to (as a spare) and see if he can measure it for ya.
I'll get back to you tomorrow

RJ

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1992 YJ with 33's
 
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