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Discussion Starter · #1 ·
This is really starting to get to me. I have a 1980 CJ7 with auto and scout D44 rear. rebuilt tranny, according to prev. owner-new drive shaft( regular shaft NOT a CV shaft). I just got done welding on new spring perches for the second time and now the pinion angle exactly matches the transfercase angle. Now the angle between the drive shaft and either pinion or t-case is 17 degrees. This only has a Rancho 2.5" lift. What Gives??? Any body else running this set up??

The vib starts at 20 now and is worst at 25 and continues all the way to at least 50, but not as bad as 25. I have not taken it any faster. I'm a little scared. No vibe once I let off the gas and vibe gets worse when I step on the throttle.

What should I do?? The U-joints feel tight and look fairly new, should I try replacing them?? Or should I lower the t-case and shim the rearend to cut down on the angle.

Has anyone else had to lower a t-case on a CJ7 with a meesely 2.5" Lift???
Please Help!!!! I'm going mad. and I have to drive this out to Denver Next Week.

Bill

About ready to break out the C4 on this thing.



 

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/wwwthreads_images/icons/tongue.gif Check this: BE SURE that the driveline ITSELF isn't out of [phase. In other words, when you hold it out in front of you like a weight bar, and you roll it till the welded yolk end resenbles a big "C" when viewed from the side, does the slide yolk end ALSO resemble a "C"??? BOTH C's have to be on the shaft...it should look like a double-open-end wrench. Does it look like that?/wwwthreads_images/icons/crazy.gifIt isn't impossible that the yolk was pulled off...rotated by accident....then hastily stuffed back on. CHECK THAT and get back to us/wwwthreads_images/icons/frown.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 
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Discussion Starter · #3 ·
Yeah, checked that awhile ago the rechecked it then rechecked it again and its in phase.

Right now, there is only about 1/2 to 3/4 of an inch of play left en the slip yolk. Would this cause vibration.

Of all the stupid things, I am changing the u-joints just for the hell of it and one came out no prob. the other, well, when I press (Hammer and Socket) it through, the body of the joint is hitting the dtive shaft before the cap is pressed out the other side!! How in the hell can I get this thing out without destroying it? I think it is brand new and if this doesn't solve the problem I wanted to use these as spairs.

So what do you think about the driveshaft angle?? Is it possible that I should lower the t-case?

Bill

 

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/wwwthreads_images/icons/tongue.gif What I usually do is press each way to get the caps out far enough to remove. Do you mean that you only have 1/2" to 3/4" of splines inserted in the slip yolk?/wwwthreads_images/icons/crazy.gif

CJDave
Quadra-Trac modified by the crack moonguy/wwwthreads_images/icons/wink.gif/wwwthreads_images/icons/smile.gif/wwwthreads_images/icons/tongue.gif transfer case team.
 
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Discussion Starter · #5 ·
Well got the U-joints out. I grabbed the cap with some vice grips and twisted it out and I dont think it wrecked it.

As far as the slip yolk goes, there is a screw on cap sorta thing that will not lit the drive shaft come apart. So when full extended there is 3 1/4" of travel. When on the jeep I'm at about 2.5 of compression and only about 3/4" of extension. I can't see any splines when it is fully extended so, I'm assuming that there is still full contact. Make any sense??


By the way, u-joints did nothing. Time to try lowering the t-case and shiming up the pinion.

Is it possible that it could be the t-case itself? I read an earlier post that said that if the bearings are shot it will leak oil, but I have no leak and there is no play at the t-case nor at the pinion for that matter.
There are 2 spider gears with 1 chipped tooth each, but I just cant imagine that it would cause this much trouble.

Any other suggestions?? How about how much to lower the case?
Bill

Is it miller time yet??

 
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Discussion Starter · #6 ·
Here's what I did to lower the case in my YJ. Buy some stock 1" x .25" bar. Cut it to length, and drill holes for the xmember bolts, then stick the bar between the frame and xmember. Then you can gradually lower the case by inserting more bars as needed. Time consuming, but cheap and strong.


 
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Discussion Starter · #7 ·
I'm actually going to use some 1" square tubing as a temporary "fix". If it works I might try the strip steel thing, just dont have any here right now. So did you use longer strips and drill three holes or smaller ones with one hole each?

Bill

 
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Discussion Starter · #8 ·
If you've got 17 degrees of difference between the angle of the transfercase output shaft and the pinion, your likely to find the problem there. Bottom line is a u-joint should not exceed 3 degrees in normal operation. If you split the difference, you'd have 8.5 degrees at either u-joint. You need to install a CV type driveshaft and attempt to reduce the u-joint angles to 3 degrees or less.
Are you sure the vibration is coming from the rear? You can remove the driveshaft and check for side play at the rear output yoke (indicates bearing failure) or remove the front driveshaft to remove the possibility of that being the fault. Also, rotate the wheels front to rear and see if the problem goes away or varies from the present situation. 2.5" of lift isn't so much, but in a short wheel base vehicle can still be a major problem. The pinion angle should not match the x-case angle exactly. It should be off by .5 to 1 degrees to prevent harmonic problems at given rpm ranges. Your probably okay though because it is really difficult to match exactly and suspension movement will keep it from being an issue in most cases. I'm still hung up on the 17 degrees.
That is alot of difference. I run my driveshaft at 14 degrees with a CV unit.
This allows for a total of 6 degrees off the negative 7 of the x-case and the pinion is up at 11 degrees. That gives me the max normal angles at the CV and 3 degrees at the diff pinion. Measure the crankshaft angle (off the face of the x-case yoke), minus this from the driveshaft angle. If it exceeds 3 degrees, you need a CV joint there. If it would exceed 6 degrees, you need to lower the x-case within that limit. The pinion should be within .5 to 1 degree. If the pinion is turned up more than about 10 degrees, you need to modify the diff cover to allow for higher oil levels to prevent pinion bearing oil starvation. Also, higher oil levels may induce seal leakage at the outer axle seals so you may need to remove the brake backing plates and use a RTV sealant around the flanges to prevent this. I love this 4x4 stuff, don't you?

 
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Discussion Starter · #9 ·
Yeah, I really feel that the 17 degrees is causing the vibe now. I lowered the t-case by one inch and didnt do much good. I will rotate the pinion up tommorow to see if that helps. Tom Woods site states that the max operating angle is up to 15 degrees. It will shorten the life of the u-joint though. But this is radically different than the 3 you mentioned.

I dont think its in the tire becuses when I put the tranny in neutral while going 25 to 30mph, there is no more vibe. Back into drive and vibe is back.
I think I might have to go with a CV shaft, but I just can't spend the money now.

Bill

 
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Discussion Starter · #10 ·
If you think the rear driveshaft might be the case...drop it for an hour and take it for aride with just the front one in...put it in 4 high with no rear shaft....still vibrates...something in the front or the rear end itself....star eliminating stuff.....put the rear tires in the back...rotate everything.....tires cause BIG vibration...check weights...bends etc....even a new looking tire can break a steal belt and cause misbalance. It your jeep alligned? Does it "dogtrack" when driving straight, both the front and rear tires should pass over the same path....you can check this easily by driving on soft ground or through a puddle...STRAIGHT..there should be two tracks for each side. But...try excluding the rear driveshaft first and go from there...my .02

CJ-7 10"lift

 
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Discussion Starter · #11 ·
Bill,
First of all I don't think wizbang is picturing what you have going. If I am correct, you are saying that the angle at each end is 17 degrees. Sounds like he is picturing that you have 17 degrees of difference between the two. When he says 3 degrees, that means the angles of the two ends should be within 3 degrees of each other. You already have that. I think sheesly is onto something and said the same thing I was thinking of by removing the rear shaft and just driving it in 4hi with the front end pulling you and slowly eliminate things.

 
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Discussion Starter · #12 ·
One of the best investments I made was for the CV driveshaft. I dicked around with the driveshaft angle for a long time....I could get it good for normal driving, but when I let off the gas it would vibrate....or vice versa. The main problem is that the angle between the diff and tranny changes based on load...accel and the diff points up...decell and it points down...unless you can keep your springs from letting the diff twist....you will not be able to get it perfect.

Buy the CV driveshaft.....its about the best $250 you will spend....I got mine from 6 States Dist.

John......southern CA
84CJ7, 3"lift, 32"BFG, 4.10's, ARB Locker, Solid Axle's, Durabak
 
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Discussion Starter · #13 ·
I'd really like to try driving it without the rear shaft, but the front r&p is in dire need of replacing so that wouldn't work. But, I think it is solved. after dropping the t-case I drove it and still vibes, then this AM I put the 2.5 degree shims back in and WHHAALLAAA No more vibe. Well Ok still a little one at 50mph, but now the life of the u-joint went from hours to months. I can live with it now. Actually I think that I over rotated by about 2 degrees so with the shims its only about 1/2 degree off. The shaft angle is now only in the 11 degree neighborhood. I am going to try some 4 degree shims to see how that does.

Take home message is that I should have checked the drive shaft angle before I welded the perches back on. I thought it would only change it by maybe 2 degrees, but it actuall changed from 9-10 degrees to 17-18 degrees and the u-joints could not handle that angle. Basically I eliminated one vibration and caused another. But at least I can get to Denver now.

Thanks for all the help
Bill

 
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Discussion Starter · #14 ·
i might be mistaken, but i dont think that anyone has mentioned axle wrap under torque. you state that the angle of the pinion matches that of the tcase, well, the problem here is that when you are accelerating, the torque of the axle twists the pinion upwards. this means that while under acceleration, the pinion goes up about 2-3 degrees, and when you let off the gas, it drops back to normal operating range. you have the angle set up for normal operating range, but what you need is to rotate it about 2 degrees down so that when it gets torqued (accelerating from 20-50) it reaches its optimum operating angle. rather than shimming the pinion up, try shimming it back down to -2 degrees optimum operating angle. i hope that helps you out.

'95 Jeep Wrangler Sahara
33"s, snorkel, 1000+ RTI, Warn xd9000i
 
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Discussion Starter · #15 ·
Thats how I rewelded the perches. I had about 1 degree more flat pinion angle to try and compensate for that. Problem was that the drive shaft angle was too steep, So I think I have to find a balance between driveshaft angle and t-case to pinion angle difference to get by until I can swing a cv shaft.

Thanks
Bill

 
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Discussion Starter · #16 ·
chances are you'll never get it PERFECT! lifting is a pain when you'r driveshaft is less than 2 feet long! The axle has been replaced so have you checked to make sure the yoke is centered side to side the same distance as the transfer case yoke?

Al
My web page
 
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Discussion Starter · #17 ·
The only way to check ujoints right, is to take out the shaft and check the joints, why??, is because I checked them in the jeep, and they felt good, but!!, they were bad, and the metal shavings kept them tight. second, is check the ears on the yokes, make sure that the tabs on the sides of the yoke are the same size, I've found that they are not alwayes the same thicknes, this will cause the joints to be off center, I also hope you don't have a Q trac, system with a centerd rear axle. that won't work.
Mike.

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Mike Duncan
[email protected]
 
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Discussion Starter · #18 ·
Yep checked them with the shaft out and mad sure the yolks were good. Even replace the ujoints though they were brand new. I'm trying some 4 degree shims today. with the 2.5 there is a little vibe at 50-60. So, we'll see

 
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