Cj5 1974 Rear End Vibrations

Hi, I am trying to identify and (hopefully correct) a huge vibration at high rev. I first changed all 4 U-joints with no success. Removed the front driveshaft and no change on 4H. Then removed the front driving shaft, trying to isolate the vibration. Could not do the test because without rear driveshaft...I think I have 4 neutral positions. The front axle is never working. Lack of time (and a golf game) put all this back in place and the vibration is still unidentified. A few questions remain:

• Can I open the transfer case and see from under whats going on? (to get the front axle working)
  
• As far as the vibration. Should I get the rear driveshaft checked and balanced? Could it be the rear axle? Should I look for a CV rear driveshaft?

thanks everyone for helping.

YH

 

A few questions.
When do you feel it?
On the gas?
Off the gas?
Light load?
In all the gears?
Hi and Low?
U-bolts and spring pads in good shape?
Do you know what the output and pinion angles are?
Could it be the tires?
As far as your front end, sounds like a linkage issue assuming your hubs are locked in.

 

Do you have locking hubs? Can you turn the front driveshaft by turning one front tire with the other tire on the ground?

 

Thanks for the interest. Here is the info:
The worst vibration is happening in second gear. At he highest RPM of the second gear, it looks like a drivetrain vibration (Probably feeling worst on the right side of the jeep...(just an impression). This is when gas is ON. At this point, when I cut the gas, a dash vibration suddently adds up. I don't feel much of a vibration at the end of the first. Vibration is also not as bad on the third (Maybe the rev is not enough)

I would have to remove the rear axle cover to look for ring and pinion. I believe the Jeep is stock as per what the seller had told me then.

As far as locking the front wheels, I have never tried this. I am also not familiar with this function. I would always drive 2H. I was just trying to activate the front end while removing the rear driving shaft to conclude if the vibration was coming from front or rear.

Thanks for the help

 

Yes, there are locking hubs in the front. Is there a procedure to test the transfer case/drivetrain functions? Thanks

 

These are one of the hardest things to diagnose without being able to see it in person. Here is a list of where I would start.
Check motor and trany mounts for failure or loose bolts.
Check body mounts for failure
Look for spots where the power-train might have be rubbing on the body during acceleration.
What condition is the fan in and does it have a clutch on it?
Do you know how old the pressure plate and disk are?
Are the driveshafts phased correctly?
Verify T-case linkage is hooked up, turn the lock-outs so the arrow points at the 4 not the 2 then you can pull the rear shaft and test it.

Are you new to this jeep?
Did the problem just appear or get worst over time?
Does it go away when coasting in neutral?
Does it happen when decelerating in gear?
What does it look like?

Pics go along way
engine
suspension
driveshafts
lock-outs
exhaust

 

You will have to invent a procedure. Understand how the transfer case and axles work and devise ways to separate the function of each. Then try each test.

I would start at the axles and work inward.

I repeat "Can you turn the front driveshaft by turning one front tire with the other tire on the ground?" Let's see if the front wheels are connected to the axle and front propeller shaft. With the transfer case in neutral, jack up one front wheel and turn it. The front propeller shaft should turn.

I suggest this because you can drive on the front axle and remove the rear propeller shaft, and see if the vibration goes away. This would answer eliminate the question of a CV driveshaft, if the vibration is still present.

You can take the pan off of the transfer case and look, but I suspect you will not learn anything.

If the vibration changes with the transmission gear, it's likely not the propeller shafts or transfer case. If the vibration gets less shifting fron second to third, I would suspect the transmission front main bearing. In third gear, the input shaft and main shaft are solidly connected, and the front main bearing bears less load.

What engine? 3-speed transmission?

 

Thanks,
It is a v8 304 3 speeds.
I tried the front wheel test this morning. Raising a front wheel, the front propeller shaft is never turning at any transfer case position, regardless if the hubs are locked or not. It's like if the front is not working at all?

 

Have you verified that the linkage is hooked to the t-case?

 

I would pull the hubs off and inspect. Then I would remove the front axle cover and inspect.

 

Since this only happens at high rpms, I would also be looking at the flywheel or clutch pressure plate out-of-balance. Does the vibration continue to get worse the faster the Jeep travels, or is it worse the higher the engine revs? A driveshaft or similar issue would be speed dependent, not engine rpm dependent. It sounds like an rpm dependent problem. I believe 304 takes a different flywheel from a 360, so could you have an incorrect flywheel for your 304?
-Donny

 

Hi, Yes I am new to CJ5. Had a brand new Wrangler 2015 but now prefer vintages as a second driver. The body is nice however the mecannic need some love.

Did some further inspections yesterday to solve the vibration issue. I believe I found the problem. The right exhaust pipe is touching the frame. This pipe was probably hardly hit and almost melt into the frame support (See pics). Also, there is a solid (metal) connection between the pipe and the transfer case housing. This should not help. Please advise if this connection is normal. I will need to get a new exhaust. I guess I should keep it dual? What do you think. Are the pipes (Front and rear) still available on the market or they need to be custom made?

On the transfer case issue, I also removed the transfer case cover, got rid of the foamy oil and loosened up the linkages. Everything works fine now. Just a little play on the output rear bearing. Does anyone knows if it is an easy bearing/race replacement (No special tool and without removing the TC) or it is painful. If so, I would keep it that way for now. Interestingly, the pattern is different than most. From front to rear, it is 4H-2H-N-4L. Is it a special Transfer case version?

Thanks for everyone's help.
YH

 

Different from most? In what way? Pattern was unchanged from 1972 through the end of the CJs.

 

A single exhaust is plenty on a CJ and judging from the pics the rest of it might need some attention.

 

Hi, Did additional testing this morning.

After moving away the exhaust from the frame, I removed the rear propeller shaft to isolate both ends.

Put the CJ5 in 4H, locked the hubs and went for a ride. The awful vibrations disapeared. I do conclude that it is coming from the back.

What's' left for inspection? The Transfer case and the rear axle both looked fine when opened, cleaned and refiled on Thursday. Other than a little play on the back bearing of the TC, I only see the rear propeller shaft as being the problem!

Am, I correct in my thinking? Do I look to re-balance the propeller shaft or get a CV shaft.

Thanks for the help.

YH

 

how are the ujoints? properly phased?slip joint?

 

U-joints are brand new. Shaft is in phase. might be 180 degrees off..I would need to try. I also saw that the weight for balancing is gone. Maybe that's the problem.

 

Hi,
Still working on this rear end vibration issue.
Definitely it is in the rear end. (Riding without rear driveshaft on 4H eliminated the vibration.)
I sent the rear driving shaft for balancing and inspection. Put it back on the CJ5 and vibration is still there. Started to read about pinion angle. Bought a digital level from amazon. Here are the findings:

-The Transfer case output is 4.05 degrees below the horizontal
-The Rear Axle Nose is 10.7 degrees above the horizontal.
-I then calculate the pinion angle at 6.65 degrees.

Could this explain the vibration. ?
How could this be if i still think this CJ5 had no lift?
Should I buy a 6 degrees shim to lower the nose of the Rear Axle?

Please help. Thanks

 

Look at Tom Woods Drive Shaft website .

The drive shaft angle is the problem on these jeeps .

I have the same problem .

Do You have A lift on Your Jeep .

I have A 2 inch Lift .

Didn't have problem until I installed the lift.

Not sure what the cure is if there is one.

 

The angles of the transfer case and rear pinion should match. Study Tom Woods site, you'll understand it. Those angles are what is causing you problem.