new gears, bad vibs and whine?? (1 Viewer)

Joined
Nov 28, 2011
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576
 
Which end should the slip joint of the rear drive shaft be on? Diff or transfer case?
 
Joined
Nov 28, 2011
Messages
576
 
I am going back to the beginning now that the truck is back in my hands. When at the shop Thursday the guys pulled the whole front end apart again and we looked at the front diff together. There is nothing to lead me to believe it is set up incorrectly. The patterns are good, there is no contact anywhere in the carrier or the housing, backlash and preload are also within spec. We did find a worn out birf, so we replaced it while it was apart.

This morning I have driven the truck and the noise is still there. I pulled the rear shaft (they said they did this) and drove the truck. I had done this previously with the front shaft, but not the rear. The noise was still there, but not nearly as bad. I am thinking I will pull out the spacers from the springs front and rear to lower the truck 1" all the way around and see if this changes things. If it is both shafts, then this should fix the problem. Then I can either reinstall spacers and address driveline angles or leave them out and trim the fenders a bit to allow clearance for the 37" tires. What do you think?

Also which way does the rear shaft need to be installed? It was installed with the slip joint closest to the transfer case, but the front is installed with the slip joint closest to the diff.
 

Delancy

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Sep 16, 2011
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Think the slip yokes are always on the differential end.

Mine were when I bought, and have no reason to believe they were ever touched.
 
Joined
Jan 26, 2006
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Hot Springs, AR
 
 
I am going a different direction at this point. The guys that have been working on the transfer case pulled the VC and replaced front and rear bearings. Noise is still there. They are charging me $0.00 because they couldn't figure out the problem. I give them a big thanks for being honest and doing the right thing in the end. I am picking it up tomorrow and I will measure drive line angles and see if I come up with anything decisive there. After that I guess I will have to pay someone else to look through the diffs. So far this hasn't cost any extra money, but shipping diffs and having them rebuilt is going to be very expensive. What's the best way to ship a diff housing?
I am sure there are many places in your area to rebuilt the cruiser diffs. I would search around with the local clubs.
 
Joined
Nov 28, 2011
Messages
576
 
Well, I don't understand why this problem showed up so drastically when I put the gears in, but it did. I removed my spring spacers all the way around the truck (lowered whole truck 1 inch) and the noise is 90% gone. Now all I can hear is the whining gears.

Now the question is: should I raise it back up and address driveline issues or leave it and trim the fenders to allow for full suspension cycle with the 37s?

I will search around but of anyone has a link to a good fender trimming writeup please post it up.
 
Joined
May 10, 2011
Messages
320
 
...why this problem showed up so drastically when I put the gears in...
The propeller shafts are now spinning at a faster rpm for any given speed on the road when compared to the stock differential gear ratio. A U-joint's rpm limit generally varies inversely with the angle of its operation, so the combo of lift and higher rpm has found the limit, particularly if the flanges at each end are not parallel to each other.

The 1996 FSM shows the dust covers facing forward on both shafts (skinny end forward, fat end to the rear).
 
Joined
Feb 12, 2016
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382
Location
Northern California
I just had new gears ( 4:56 ), Harrop rear locker and new Birfs installed by a well known cruiser guy, picked it up yesterday. Oh also I have stock height OME springs which gives a 3/4" lift or so and 33" tires. Anyway ... When I picked it up, He said to drive it up the freeway at 65-70 mph to get the gears hot then stop and let them cool off. I did went about 12 miles up the freeway, stopped at dennys for lunch.... then started on the way home ( another 75+ miles ) of which he said to drive normally but at 55-60 mph. I did and no noises had that extra umph going up hills that I wanted. Got home and took a nap for a couple hrs, then went to a meeting last nite thats about 20 miles way... drove it at 45-55 mph to the meeting , still fine no noises. Then after the meeting, drove home same way , same speeds, and there is all this grinding noises going on sounds like in the front, right side and front in general and the rear on the deceleration, al though theres some in the front on the gas too. I texted the installer, and he said to check the drive shaft flanges at the pumpkins... so that'll be done today, but my question is ... if I have to drive the near 100 miles back down to his cruiser only shop, will driving it be detrimental ? I'd think so , buit wanna check ? any thoughts would be great too ? Thanks in advance !
 

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