Right now, unloaded, the rear is at an effective 20-3/8" (subtracted the 1" body lift).
Don't know what my GVW is right now ...
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Don't know what my GVW is right now ...
- Thread starter
- #62
How come even your tape is better than mine? 
I would be surprised if there is any axle wrap- 4 link suspension- with MT uppers and lowers- poly bushings- leaves little wiggle room for movement - inconsequential movement anyway. You can check this by mounting your camera again, and putting it in drive and holding the brake pedal while applying throttle- if there is movement- you'll see it at the 3rd. You can also try that with the ebrake as a second test.
Good plan with checking runout on diff , flanges, tcase and axles.
Good plan with checking runout on diff , flanges, tcase and axles.
- Thread starter
- #64
Almost exactly the same as what you have. If you grab at the outer slip yoke, you can get just a tiny bit of wiggle pushing up and down. Just enough to feel it tick but not enough to really see it move. Don't know how much play is within the acceptable limits. The slip yoke does move very easily in and out.
- Thread starter
- #65
Update: so after being at the driveline shop all week the owner is just as stumped as I was. He was fairly certain that it was loose splines on the slip yoke. He put the shaft in a hot bath to clean any contaminants and found that the play snugged up with insertion so we extended the shaft hoping this would be the cure. No change. :-(
He then put dials on the hubs and flanges. Hubs appear to be true which is what I expected as it doesn't vibrate with the rear propeller shaft out. There is some runout in the brake disc and the caliper studs don't slide freely so that probably needs to be addressed, but isn't likely the cause. The pinion flange is pretty far out. As in 0.025" out at the rim. Measured at the pilot side its 0.015" out. No visible damage though.
So I've got a new pinion flange on order an will convert from crush sleeve to solid spacer. The plan will be for him to remove the 3rd and put the pinion on a lathe to make sure there's nothing going on with it being bad or bent. He'll, of course, also check everything related to the ARB and ring gear and hopefully eliminate the third from being a potential source. Unlikely, but there could be something defective inside the ARB locker. Locker engages and disengages smoothly and reliably.
Hopefully the new flange will be the trick. I just don't have a strong sense that is it though. That there's no impact, that it was running fine for two seasons prior, and that the vibration goes away with constant torque and brake application makes me think it something else. There is a battle scar on the bottom of the third that looks new, however it's only on the housing. Can't imagine how that would affect anything mechanically.
Not having any other plausible explanation, the only rational decision is to keep trying the most likely possibility until we (eventually) hit gold.
He then put dials on the hubs and flanges. Hubs appear to be true which is what I expected as it doesn't vibrate with the rear propeller shaft out. There is some runout in the brake disc and the caliper studs don't slide freely so that probably needs to be addressed, but isn't likely the cause. The pinion flange is pretty far out. As in 0.025" out at the rim. Measured at the pilot side its 0.015" out. No visible damage though.
So I've got a new pinion flange on order an will convert from crush sleeve to solid spacer. The plan will be for him to remove the 3rd and put the pinion on a lathe to make sure there's nothing going on with it being bad or bent. He'll, of course, also check everything related to the ARB and ring gear and hopefully eliminate the third from being a potential source. Unlikely, but there could be something defective inside the ARB locker. Locker engages and disengages smoothly and reliably.
Hopefully the new flange will be the trick. I just don't have a strong sense that is it though. That there's no impact, that it was running fine for two seasons prior, and that the vibration goes away with constant torque and brake application makes me think it something else. There is a battle scar on the bottom of the third that looks new, however it's only on the housing. Can't imagine how that would affect anything mechanically.
Not having any other plausible explanation, the only rational decision is to keep trying the most likely possibility until we (eventually) hit gold.
Dennis, any update on this?
- Thread starter
- #67
New pinion flange and hard spacer came in Friday. Going in tomorrow to have it R&R'd. Hopefully this does the trick.
I've been chasing the same problem as you since I had my gears and lockers installed. I have tried just about everything you have mentioned. Today I measured the runout on my pinion flange at 010 inside the bolt circle and 025 at the edge. I compared that to my other, unmodified truck (that has no vibrations) and it measured out less than 001. The max spec is 0039, the rear diff is going into the shop tomorrow for a full check and a new flange. I never suspected anything in the diff based on the expected quality of the work that was done. Hope you have found the source of your vibes, I will check back in after I get mine reinstalled.
- Thread starter
- #69
Was sent the wrong flange. Correct (29 spline) flange is coming tomorrow.
- Thread starter
- #70
New flange reduced the runout from 0.025 to 0.008. No change in vibration.
Headed out to fill up all of my 5 gallon Scepter cans with fuel so I can douse it and set fire to it. Argh.
Headed out to fill up all of my 5 gallon Scepter cans with fuel so I can douse it and set fire to it. Argh.
- Thread starter
- #72
Not sure what spec is, but it's a 66% reduction with 0% change in vibration so we're not thinking it's the source. Further the flange had virtually zero runout when checked into the lathe so the runout that is there is coming from the spline interface with the pinion. Going to try to roll the pinion down a degree tomorrow to see if that has any effect.
guerasfj60
SILVER Star
Any news?
- Thread starter
- #75
So back in March I ended up using the MetalTech upper links to adjust the pinion angle. At the time I felt that this made considerable difference. However, since then it has seemed to get worse. I pulled the front propeller shaft today just to see if that would make any difference and it made zero. The only thing that made it go away was pulling the rear shaft and running in FWD. Going to explore more of what's going on with those angles and that shaft. It runs flawless on the trail and up until 55 on the highway. Frustrating. I wish there was a local shop I trusted to bring it to resolution.
Sorry, I didn't get to read the entire issue you posted. Just wanted to check, did you use OEM U-Joints? A small play at the splines is ok.
- Thread starter
- #77
Never replaced them. No signs of wear and swapped shaft with another 100 and no change.
How about the front drive shaft?
- Thread starter
- #79
It's in good shape. You can pull it and drive in RWD and the symptoms don't change.
I have been chasing a minor vibe- presents itself above 55mph and typically is noticeable on acceleration. Ive been able to adjust, and balance most of it out. Ujoints were replaced in January with OEM, but it never felt like they got it balanced correctly. Since then I've had the DS off a few times and rebalanced, the last time was after a minor rock scrape left a nice gouge in the DS. The repaired and "straightened" but the vibe was still present. I took it back and asked them to rebalance high speed- (3000 rpm) which did help considerably. Point is if you dont ask them to go the extra step for high speed balance- the tech running the balancer usually goes for "close" and moves on to the next job. I also adjusted the pinion again which was not optimal. These drivelines seem really sensitive to angle variations, especially when theres been some added weight: I have front & rear bumpers, winch, sliders and skids. 1 or 2 degrees out and you'll get some vibes.
What are your driveline operating angles?
Output Flange:
Driveshaft Slope:
Diff Flange:
If you have fresh UCA and LCA bushings, there is virtually little or no axle rap to account for respective of diff angle set up ( so Ive been told). So making sure there is at least 0.5 to 1.0 degree difference between the output flange and diff flange is key, and the direction of offset is critical. If the output flange is pointing down -1 degree, you want the diff to point up +1 degree so that the offset is parallel.
I created an illustration of my current set up, which is pretty close to where it needs to be. I would like to adjust a little more upward another .5 deg, but to do so I need to remove my MT uppers to adjust, which is a pita. Wished trailtailor would have had those turnbuckle type UCA's when I was shopping for UCA's. Adjusting while connected to the truck is so much simpler.
Ive also attached a driveline Vibe diagnosis spreadsheet. I found this on another truck forum that I thought made some sense.
What are your driveline operating angles?
Output Flange:
Driveshaft Slope:
Diff Flange:
If you have fresh UCA and LCA bushings, there is virtually little or no axle rap to account for respective of diff angle set up ( so Ive been told). So making sure there is at least 0.5 to 1.0 degree difference between the output flange and diff flange is key, and the direction of offset is critical. If the output flange is pointing down -1 degree, you want the diff to point up +1 degree so that the offset is parallel.
I created an illustration of my current set up, which is pretty close to where it needs to be. I would like to adjust a little more upward another .5 deg, but to do so I need to remove my MT uppers to adjust, which is a pita. Wished trailtailor would have had those turnbuckle type UCA's when I was shopping for UCA's. Adjusting while connected to the truck is so much simpler.
Ive also attached a driveline Vibe diagnosis spreadsheet. I found this on another truck forum that I thought made some sense.
