I have a 1997 F350 4wd. I drive like an old man but even driving this way every time I pull away from a stop (with an empty bed) I get rear axle wrap and then a bump from the rear end as the springs stop the rotation and I pull forward. I don't believe anything is wrong with the truck, I think it is just the nature of the factory setup. I am just getting tired of the bump and would like smoother starts and stops (when the truck is not carrying a load).

My question for those in the know is: What is the least expensive way to keep the rear axle from rotating when starting out and when letting off the fuel?

TIA,
Blane

 

sounds like your rear springs are bad. or soft.
Roadmaster seems to have a fix for it called active suspension. https://activesuspension.com/suspension-kits/

 

I know you said you believe the truck is fine. But, I had a similar issue with my 5.0 5spd truck and it was due to broken springs that couldn't be seen until I took the bolts loose.

 

First, check the springs and spring mounts closely. Jack the truck up by the frame to see if things move when they shouldn't, like worn eye bushings, loose u-bolts, worn or broken shock mounts. Next, check your slip joint in the driveshaft and the condition of the U-joints. My brother's Ranger did exactly what you described, turned out to be a dry slip joint in the driveshaft. A bit of moly-based chassis lube later, it was okay, that clunking gone.

 

Ditto on the slip joint. If your particular truck has one (or more?) they should certainly be checked. And cleaned and lubed if needed.
An F350's springs would not normally allow for much axle wrap under normal conditions. I know the old Broncos had lots of wrap, and even more with aftermarket springs, but I would not expect the 350-rated springs to have this same issue.
At least not to the same extent.

So well worth checking for broken springs as that's what others have had happen. And for sure the drivshafts, pillow blocks, carrier bearings, and any other such stuff your particular truck might have.
Is it a standard, or Super Cab?

Paul

 

Thanks for the replies. They certainly give me some things to check. The truck is a 8' box with standard cab.

It is interesting that after I changed the rear U joints last year the axle wrap went away for about a week. After that it came back again just like before. I am not sure what to make of this but if I had bad springs, loose bolts in the hangers or perches, (there is no carrier bearing on the one piece driveline), or other loose items it doesn't seem like the axle wrap wouldn't have briefly gone away like it did. I also recall that when I had the transmission rebuilt and reinstalled the axle wrap was gone for a short while then too. Putting these to things together it seems like it is driveline related.

Thanks again,
Blane

 

This is where you need TSB's for the period.

You are experiencing spring wrap. If not factory equipped, you can put spring clamps on the leaves to control it.

You might also want to verify correct Pinon Angle.

 

Well, changing u-joints didn't do anything to change any spring-wrap/axle-wrap issues. It simply changed whatever symptoms you're experiencing.
But that does at least give some more clues as to what it might be.

Agree, in general terms. But working on the shaft may have loosened up the slip splines temporarily.
Did you by any chance grease the slip shaft section while you had it out?

If yours is like mine, you have a single cardan rear shaft then? Where there is only a single joint at each end, with a slip-shaft section on the shaft? Many (most?) 2wd trucks would have the slip splines at the transmission output rather than on the shaft, but your 4wd version should have a slip-spline section on the shaft.
One thing you can try that's easy and cheap for now, is to remove the shaft again and literally separate the two halves. Clean the splines good, look for any nicks or burrs or deformations that might be present, re-grease it good with a high-quality grease of some kind (boat trailer wheel bearing grease maybe?) and see if it temporarily goes away again.
If it does, but again comes back in a short time, you likely have worn splines beyond their normal life and may have to replace them.
If it stays away for longer this time, you're on to something and may just need to re-lube it more often.

Just watch how much you put inside there when it's apart. Don't pack it full or you'll have a big mess on your hands.

Yep. Totally.
It can still be normal axle wrap, and the symptoms go away when you mess with something. But more likely than not you're experiencing the slip-shaft issues described previously.
Especially if you can feel a mild "squat" of the truck when you take off and hear the clunking or other sounds. It's the shaft's splines binding then releasing.

Paul

 

Is this an auto truck or manual?

 

Thank you all for your comments and suggestions. You have given me many things I need to check out. I will start investigating things after work tonight.

Comments, answers, and questions.

1. Everything on the truck rear drive line and springs is stock. I am not sure how the pinion angle would change from the factor set up. Is this possible in my scenario?

2. Are the TSB's posted somewhere on the Internet?

3. The slip joint discussion has me intrigued. I know some have said it could be this and someone else it is probably not this but when the tranny was rebuilt and when I removed the driveline to replace the u-joints and the issue went away temporarily both times the common denominator is that the slip joint was exercised. I am still not sure why a stiff slip joint would cause spring/axle wrap. It seems to me it keep the axle from rotating.

4. I don't feel the struck squat at all when I take off. I am pretty sure that when I take off the axle rotates until the main leaf springs bump up against the overload springs. To further make me believe this is what is happening is that the spring/axle wrap issue goes completely away with a ton of pellets in the bed or when I pull my 14,000 pound trailer.

5. I hear no hard clunking sounds, like metal hammering on metal.

6. The rear shaft two pieces with a slip joint between them.

7. The truck is a automatic.

Thanks again for all the suggestions.

Blane

 

Not really. Unless something literally was broken and tweaked, the only "normal" time that your pinion angle should change is when the ride height changes.
And even then it's not always changing in a bad way. So if you went from an empty bed to a 10' cab-over camper, it "might" change.

Good question. I bet they are.
There's a guy on SuperMotors goes by the username Steve83 and he has a ton of Ford TSB's posted up on his pages. Not sure if they reach all the way up to your year, as he certainly concentrates much of his info on earlier models. But it's worth a look.

Again, it's not "causing" anything relating to axle-wrap (or spring-wrap) in any way whatsoever. It's simply capable of causing the symptom you reported.
When you said you're experiencing axle-wrap, how do you know? Have you looked back there while someone accelerated from a stop, or put a GoPro down there to watch? What makes you think that what you're feeling/hearing is axle-wrap?

In fact, most vehicles with leaf springs experience some level of axle-wrap. How much happens varies widely, but an F350 has less than some others due to the design of the spring pack, and just the sheer stiffness of the springs.
The amount can change over the years as springs fatigue, but you don't usually feel the springs themselves. You feel subsequent actions related to it.
In the case of the slip yoke, it's there to allow for compression and extension of the driveshaft as the suspension cycles. It cycles slightly every time you accelerate and decelerate, so sometimes the slip shaft just needs to move. If it's not moving right away (I would call it "stiction" in it's action, if not in actuality) then suddenly releases under the torque of the weight of the truck and changing suspension height. Boom-clicka-boom and a squat later (more so with softer springs), you feel it in the rear end.

Here again too, the slip yoke is not the only thing it can be. We can't tell from here just from your description exactly what's going on with 100% certainty though. So the slip yoke sticking is just a guess with a higher percentage chance than some of the others.

Of course! Well, it doesn't literally "go away" but it does change quite a bit. The springs are under dynamic forces that change as their arch changes (ride height), the weight on them changes, and all those other things.
The fact that you don't feel it squat is a good clue. But not a guarantee either. Because the springs are so stiff, and because sometimes the overloads are in contact and change the load capacity massively, your rear end does not squat under accel like it would in a Bronco or F150. It might still squat, but it's minimal. Especially when empty.
But that's a good observation and may indicate towards something else, other than the slip yoke. But I'd still check it. They do in fact wear out, just like anything else that moves under heavy loads and twisting torque.

Ahh, then you're likely on to something with the overloads flapping. Maybe it's just the old main leaves getting a little tired and are doing something they didn't do before. Allowing more wrap, but also sitting maybe just a tiny bit lower than before, to put the overloads in closer proximity.

Simple setup, but they do wear out...

Smoother delivery, but often more toque multiplication to the rear end.
Maybe the old GoPro method isn't such a bad idea at this point.

Paul

 

1TonBaseCamp - Thank you very much for your comprehensive reply answering my questions and further explaining possible issues. I am going to look for Steve83 on SuperMotors to see if the TSB's he has go back to 1997. Even if there is nothing related to my current issue there may be other information that is helpful to have.

I understand your explanation regarding the slip joint. Upon further thought on this subject I am going to start by dropping my driveline and greasing that joint. I think the bump I feel may be a sticking slip joint. If I take off very slow and easy the bump I feel happens further down the road than a normal take off meaning the slip joint may be sticking longer before it lets loose. This concept is also supported by Raystankewitz's experience with his brother's truck.

I don't actually know for sure if it is axle wrap as I don't have a go-pro to film what is happening and I haven't been able to get my wife to drive the truck for me while I ride in back. (She hates driving it and the last time she did she just about totaled somebody else's car at the supermarket when she torn the front end of it off with the truck's rear tire. (No damage to our truck thankfully.))

I've checked for looseness in components and fasteners while the truck was on the ground but didn't find anything. Next I need to jack it up as someone else suggested and look again. I did find a little bit of looseness between the truck bed and the frame at one location and it looked like some dampening material might have fallen out. I pounded in a plastic shim and it got rid of the slack and quieted the truck down quite a bit.

Thanks again,
Blane

 

Sounds like a plan. When you have the shaft out, but before you pull it apart (if you go that far) you can test the slip yoke for any radial play. Simply by grabbing a section in each hand and twisting back and forth to see if there is movement.
There really is not supposed to be any play, so whatever is there indicates some wear in the splines. When mine was doing it ('71 Bronco) there was not much movement to be detected, but it was there.

Mine was very pronounced due to the factors I mentioned before. Softer springs for one, but the general balance of the truck as well, when compared to a long-wheel base, stiffly sprung, short travel suspension on an F350.
When I would start off from a full stop, the "squat" part of the equation was very noticeable. And just like yours, the more gently I would take off from a stop, the farther down the road I would get before the clunk/squat occurred.
Greasing the slip yoke would make it go away for a few weeks, but pulling the shaft apart and cleaning and re-greasing that way would get rid of it for a few months at a time. But those intervals got shorter and shorter over time, to the point that finally when it would only go away for a week or so, I finally replaced the driveshaft and that got rid of it for about the next 60k miles or so.

Good luck. Hope it's that simple.
Or better yet, simple (and maybe cheaper) would be finding a flapping leaf smacking another!

Paul

 

1Ton, my experience has been the same, albeit with the slip yoke in the transfer case (scsb 4x4 f150). New yoke, been good for the last 10 years (150k miles).

 

A week or more ago I removed the upper end of the driveline and lubed the slip joint and some folks suggested. I put it back together and not once have I experienced the spring/axle bump I had been experiencing the last 8(?) years.

Thank you all for your helpful replies and especially to Ray and Paul who directed me to the slip joint as a possible cause.

Blane