Will Driving Full Float Rear End With Axles Removed Damage Differential?
#1
10-12-2017, 04:38 PM
Will Driving Full Float Rear End With Axles Removed Damage Differential?
Hi
My specific question is at the end of all of the background information below:
I have a 1994 F-250 SC 4x4 460 AT 8900 GVW that I am trying to diagnose a vibration problem.
I feel an up-down kind of vibration that is most pronounced at around 40-45 mph.
I posted a thread on the issue back in July, and I'm still trying to find a solution to the problem. Bluegrass festival season is over, so now it's time to get back to work:
https://www.ford-trucks.com/forums/1...at-40-mph.html
The rear end is a 10.25 Full Floating axle, and I removed both rear axles and had a machine shop check them. One of the axles had .035 deflection in the middle of the axle, the other was true.
I removed both outer bearings and they looked like brand new, so I didn't remove the hub to check the inners, not wanting to destroy the oil seal.
The question that I have is this: If I fab up a end plate for the hubs which would be covering the holes where the axle flange bolts to the hub to keep oil in and dirt out, can I safely drive the vehicle in 4wd without the axles being installed without damaging the differential with the driveline still attached? Both forward and reverse? Up to 45mph? The plate that I would fab up would be a flat plate just like the axle flange, but without the axles.
The ability to do this would help me determine if one of the axles is causing my vibration since if the vibration goes away with no axles installed, then the source would have to be the axles, and probably the .035 one.
If the vibration continues with no axles installed, then I'll be looking at brake drum out of balance issues, or some other issue....
Please let me know if it's OK on driving the vehicle without the axles, and if someone has any other suggestions on the source of the vibration or how to troubleshoot the problem, I would sincerely appreciate it.
Thanks
BluegrassPicker
My specific question is at the end of all of the background information below:
I have a 1994 F-250 SC 4x4 460 AT 8900 GVW that I am trying to diagnose a vibration problem.
I feel an up-down kind of vibration that is most pronounced at around 40-45 mph.
I posted a thread on the issue back in July, and I'm still trying to find a solution to the problem. Bluegrass festival season is over, so now it's time to get back to work:
https://www.ford-trucks.com/forums/1...at-40-mph.html
I have a 1994 F-250 4x4 460 SC AT 4.10 that has 150+000 miles on it that I've owned since 1997. The truck is as stock as the day that it came off the showroom floor.
The truck has never been in a wreck or hit curb, etc. and it is only driven when we pull our 24ft travel trailer or mount a 8ft Lance camper on the back.
Several years ago, I noticed that one rear tire was wearing on the outer edge, but only on 1/2 of the tire, not around the entire circumference. (Kind of like around the crust edge of a 1/2 slice of a whole pie, not the entire pie.) The tire store replaced the tire thinking it was a defect in the tire. At that time the truck had our 8ft camper mounted on it and was stored in that configuration when not used. Unfortunately I cannot remember which side the tire came from on the rear.
A couple of years ago, we took the camper off and used the truck to haul our travel trailer and I noticed an up and down movement in the truck when traveling at speeds over 40 MPH. The movement smooths out at around 50 and is barely noticeable beyond. This up and down movement was not felt with the camper on, only when it came off and there was no weight present in the rear bed. The movement is felt whether there is a trailer hitched or with no trailer. The movement is felt within the truck at the driver and passenger front seats. I have sat in the bed of the truck trying to determine exactly where the movement is coming from, but after several hours of doing so, I cannot pinpoint a specific location.
I have since replaced the shocks with Monroes, checked all front steering components and all is good, had the driveline checked for balance by Six States and rebalanced, and replaced the u-joints and the carrier bearing. No luck in eliminating the up and down movement...
I have replaced the tires with Michelen radials and the tire store did a road force balance on all tires and they checked the stock steel wheels prior to mounting the tires.
I have jacked up the truck and spun the tires with the vehicle in gear and I cannot see any up and down movement. I placed a jack stand near the tires and there is very minimal deflection in the tires.
I removed the tires and checked the runout with a dial indicator on the axle flanges and there is no extreme movement.
At this point I am stumped. Could a rear axle bearing have gone "flat" from sitting in the winter time over the years with the weight of the camper on it? Could an axle be bent, or perhaps the entire housing?
Has anyone encountered a similar situation or know of a link to a write-up or forum thread that discusses a similar problem, even if it's regarding a different vehicle?
I would really appreciate some help or advice.
The truck has never been in a wreck or hit curb, etc. and it is only driven when we pull our 24ft travel trailer or mount a 8ft Lance camper on the back.
Several years ago, I noticed that one rear tire was wearing on the outer edge, but only on 1/2 of the tire, not around the entire circumference. (Kind of like around the crust edge of a 1/2 slice of a whole pie, not the entire pie.) The tire store replaced the tire thinking it was a defect in the tire. At that time the truck had our 8ft camper mounted on it and was stored in that configuration when not used. Unfortunately I cannot remember which side the tire came from on the rear.
A couple of years ago, we took the camper off and used the truck to haul our travel trailer and I noticed an up and down movement in the truck when traveling at speeds over 40 MPH. The movement smooths out at around 50 and is barely noticeable beyond. This up and down movement was not felt with the camper on, only when it came off and there was no weight present in the rear bed. The movement is felt whether there is a trailer hitched or with no trailer. The movement is felt within the truck at the driver and passenger front seats. I have sat in the bed of the truck trying to determine exactly where the movement is coming from, but after several hours of doing so, I cannot pinpoint a specific location.
I have since replaced the shocks with Monroes, checked all front steering components and all is good, had the driveline checked for balance by Six States and rebalanced, and replaced the u-joints and the carrier bearing. No luck in eliminating the up and down movement...
I have replaced the tires with Michelen radials and the tire store did a road force balance on all tires and they checked the stock steel wheels prior to mounting the tires.
I have jacked up the truck and spun the tires with the vehicle in gear and I cannot see any up and down movement. I placed a jack stand near the tires and there is very minimal deflection in the tires.
I removed the tires and checked the runout with a dial indicator on the axle flanges and there is no extreme movement.
At this point I am stumped. Could a rear axle bearing have gone "flat" from sitting in the winter time over the years with the weight of the camper on it? Could an axle be bent, or perhaps the entire housing?
Has anyone encountered a similar situation or know of a link to a write-up or forum thread that discusses a similar problem, even if it's regarding a different vehicle?
I would really appreciate some help or advice.
I removed both outer bearings and they looked like brand new, so I didn't remove the hub to check the inners, not wanting to destroy the oil seal.
The question that I have is this: If I fab up a end plate for the hubs which would be covering the holes where the axle flange bolts to the hub to keep oil in and dirt out, can I safely drive the vehicle in 4wd without the axles being installed without damaging the differential with the driveline still attached? Both forward and reverse? Up to 45mph? The plate that I would fab up would be a flat plate just like the axle flange, but without the axles.
The ability to do this would help me determine if one of the axles is causing my vibration since if the vibration goes away with no axles installed, then the source would have to be the axles, and probably the .035 one.
If the vibration continues with no axles installed, then I'll be looking at brake drum out of balance issues, or some other issue....
Please let me know if it's OK on driving the vehicle without the axles, and if someone has any other suggestions on the source of the vibration or how to troubleshoot the problem, I would sincerely appreciate it.
Thanks
BluegrassPicker
#2
10-12-2017, 04:56 PM
I think if you remove one of those drive shafts, that side of the rear diff would spin freely with no rear drive at all, if it's an open diff. If it's a LSD, it will start spinning after about 40 lb-ft of torque is applied, and you would wear out the clutches. In either case, the spider and side gears will be spun a lot more than they're supposed to, and you could wear them out as well. You can usually hear them, as they don't mesh nicely as hypoid gears do.
How did you jack up the rear? I was trying to chase down a vibration in one of my cars before, and I made the mistake of jacking up the axle and running the rear in gear. No vibrations. I then jacked the rear end up by the frame, leaving the axle hanging, then the vibration was obvious.
How did you jack up the rear? I was trying to chase down a vibration in one of my cars before, and I made the mistake of jacking up the axle and running the rear in gear. No vibrations. I then jacked the rear end up by the frame, leaving the axle hanging, then the vibration was obvious.
#3
10-12-2017, 08:09 PM
Thank you so much for your reply, xlt4wd90.
I believe this is an open diff, not limited slip. I'll double check that.
My plan was to remove both axles and leave only the driveline attached. Would that damage the differential if it is not limited slip? I'll be in 4wd being pulled by the front wheels.
If no vibration is found with both axles removed, I would then insert one axle and try again and repeat that procedure until the vibration begins.
I did like you did, from the axle. I've been told that letting the rear end hang puts the driveline at an angle that is beyond the normal driving range and that would create a vibration, potentially. Perhaps I've been told wrong?
I think if you remove one of those drive shafts, that side of the rear diff would spin freely with no rear drive at all, if it's an open diff. If it's a LSD, it will start spinning after about 40 lb-ft of torque is applied, and you would wear out the clutches. In either case, the spider and side gears will be spun a lot more than they're supposed to, and you could wear them out as well. You can usually hear them, as they don't mesh nicely as hypoid gears do.
My plan was to remove both axles and leave only the driveline attached. Would that damage the differential if it is not limited slip? I'll be in 4wd being pulled by the front wheels.
If no vibration is found with both axles removed, I would then insert one axle and try again and repeat that procedure until the vibration begins.
How did you jack up the rear? I was trying to chase down a vibration in one of my cars before, and I made the mistake of jacking up the axle and running the rear in gear. No vibrations. I then jacked the rear end up by the frame, leaving the axle hanging, then the vibration was obvious.
#4
10-12-2017, 09:31 PM
If your center diff has a hard lock, then removing both rear axles will effectively turn your truck into a front wheel drive. But since you're trying to see if the axles are out of balance or warped, you will need them turning. I don't suppose you have access to a lathe that you can chuck it into?
I have to admit that the car I jacked up was a Mustang, which doesn't have as much suspension travel as a typical truck, so the diff did not hang down very far, and the driveline angles were not too severe. But in my case, one side shook like crazy while the other side had just the movement from being on the other end of the solid axle. I didn't have to run it for very fast or very long, so I don't think I could have done too much damage.
I have to admit that the car I jacked up was a Mustang, which doesn't have as much suspension travel as a typical truck, so the diff did not hang down very far, and the driveline angles were not too severe. But in my case, one side shook like crazy while the other side had just the movement from being on the other end of the solid axle. I didn't have to run it for very fast or very long, so I don't think I could have done too much damage.
#5
10-12-2017, 10:02 PM
If your center diff has a hard lock, then removing both rear axles will effectively turn your truck into a front wheel drive. But since you're trying to see if the axles are out of balance or warped, you will need them turning. I don't suppose you have access to a lathe that you can chuck it into?
My goal in removing both axles is to determine if my up-down vibration quits with no axles installed. If it does quit, that would indicate a problem with one of the axles and I would investigate them further.
If the up-down vibration continues with no axles installed on either side, then I can eliminate the axles as being the problem and I will investigate other parts such as spindles, bearings, brake drums, etc.
I would rather not get tunnel vision on the axles and spend money replacing one or more just to find that my problem lies elsewhere and testing without the axles installed would help.
I took my axles to my local 6-States Dist and they put them on their driveline balancing machine. The machinist stated that one had a .035 deflection in the middle of the axle. He said he wasn't sure if that was causing the problem, hence my desire to test the truck with no axles installed.
Will the differential be damaged if I drive the truck in 4wd with only the driveline attached and no axles installed?
I have to admit that the car I jacked up was a Mustang, which doesn't have as much suspension travel as a typical truck, so the diff did not hang down very far, and the driveline angles were not too severe. But in my case, one side shook like crazy while the other side had just the movement from being on the other end of the solid axle. I didn't have to run it for very fast or very long, so I don't think I could have done too much damage.
#6
10-27-2017, 09:34 AM
Cargo Master
I would try what you are thinking but go one step further and take the rear driveshaft off so the rear differential won't turn at all... but first remove that driveshaft and drive it and see if that is the problem.
ALSO... check your rear spring hangers, they are prone to rusting and becoming rather bouncy. I had the same issue in my Ranger whenever I started to reduce speed; braking or letting the engine wind down. I tracked it down to a spring hanger that was about to fall apart, I replaced both and the issue went away. For what its worth I have had that truck since it was new and there is no rust on the body at all, but the spring hangers take a beating.
ALSO... check your rear spring hangers, they are prone to rusting and becoming rather bouncy. I had the same issue in my Ranger whenever I started to reduce speed; braking or letting the engine wind down. I tracked it down to a spring hanger that was about to fall apart, I replaced both and the issue went away. For what its worth I have had that truck since it was new and there is no rust on the body at all, but the spring hangers take a beating.
#7
01-14-2018, 12:05 AM
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