Some history
88, e150, 5.0, AOD, Ford 8.8 differential,S724S NL, w/103k miles.
The van sat for garaged for many years. Not sure how long but the tires that were on it when I bought the van, except for dry rot, looked brand new and were dated 2000. I have put 300 to 500 miles on it since acquiring the van.

I know worn out spring shackle bushings can cause problems and I believe mine are dry rotted. With a visual inspection the bolts appear to be centered in the bushings as best I can tell but the bushings are cracked on the outer edges. Once stopping and letting off the brake there is a loose clank like feeling from the rear of the van. Also when going over speed bumps sometimes you hear the same noise. I know that can affect the pinion angle and cause vibration.

I noticed a vibration from 55mph to 70 mph that would fade away by 80mph. I also noticed a ting now and then when starting off or letting off the gas at lower speeds.

Right after buying the van I swapped tires and wheels with my 85 e150 which had new tires on it.. I took the van back to the shop that I originally bought the tires from and had the rears road force balanced as well as swapping the the spare rim with the left rear rim that appeared to have a little wobble in it. That did not help.. I could also her a slight whomp, whomp, whomp after 25mph.

So I removed the one piece drive shaft and took it to a driveling shop to have the U-joints replaced and shaft balanced. The front joint was very dry, the rear joint was dry and burnt, and the balance was good.

After reinstalling the drive shaft I went for a test drive. most of the vibration was gone but now it has a slight vibration from 60 to 65mph that becomes more prominent when letting off the gas. Nothing like before but approaching it when letting off the gas. It is only between 60 and 65 mph.

I wanted to listen to the differential and axle bearings so i raised the van up on stands, started the engine and put it in gear. The idea was to stop one wheel at a time and listen to each one. Both wheels started turning but by the time i could get out of the seat and to the left rear wheel, it had stopped turning and the right wheel was turning fairly fast. I tried it again and the same thing happened..
With the engine off I tried turning the left wheel by hand and it would turn about 1/2 a turn and bind then loosen up and bind again. The right wheel seems to be ok..

I dont know if you can see it in the video (video works much smoother on my computer before uploading it) but here is a video of the wheel turning.
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If you full screen the video you can see the wobble a bit better.
Another thing is when I first started the van and put it in gear for the first time the engine was cold and it was at a higher idle. When the left wheel stopped turning, the right wheel speeded up (perhaps it kicked to second gear) but it the differential made good bit of noise that is hard to explain. Much like dry or bad bearings. Will a differential sometimes make noise if one wheel is stopped and the other is turning say 30 or 40 mph? When holding the right wheel stopped with the left wheel turning I could feel the right wheel trying to pull like it was trying to catch every few seconds..

Perhaps a bent axle shaft, or shaft and bearing? I am thinking that maybe while sitting the axle shaft bearings dried out, perhaps a little rust on them.
the U-joints were original and there is no signs of anyone ever being in the differential.

 

If the diff was binding I would guess it would be locked. Seems to me like a bad wheel bearing or dragging brake.

If it's a bad diff I have the original open 31 spline diff from my '02 van (changed out to an Eaton posi when the van was new) but it would take a lot of stamps to mail it to you

Good luck.

 

Take the rear cover off the diff and have a look, if you find any broken parts then you found your problem but you can also observe everything as it spins to see if anything is lose or binding.

 

What does the NL stand for on a differential.. Limited slip and non limited slip?
Mine is a NL I understand limited slip after watching this great video.

As to brakes, when i did the front brakes I also pulled the rear drums off. I didn't have to loosen them. They looked good so I slid the drums back on.
I thought they were good that is... Today when up on stands and pressing the brakes to stop the wheels, they didn't stop... That means the rear brakes are not working. Master cylinder time... Amazed how well the front brakes work though!!
I will be taking the wheels off and will double check the binding with them off.. I think I'll swap sides with the rear wheels and see if the left one still has a wobble..

What do you men when you say it is locked?
Yes I would have to add extra stamps to pay for the weight of the stamps!


Ys tomorrow or Friday I was planing on pulling the axles so i will have the cover off..

Where can I get a new differential locking pin bolt? Ford manual states that it should be replaced when ever it is removed..

thanks..

PS. how do you check for a bent axle shaft (at home) once its out? Are they machined straight enough to use a straight edge on the shaft?

 

If a regular open or limited slip diff went bad, my thought would be that it would be stuck solid due to a bearing failure on a spider gear or something but that would make both rear wheels turn like a welded diff or a spool.

If one wheel is happy to turn and the other is not, I don't think a diff could cause that but I could be wrong. Seems like it would be a wheel bearing or something on the side that stops. Bent axle could probably kill a bearing and also cause vibrations.

Not sure about axle tags but if you check the axle code on the driver door jamb it will have a 2 digit number that will tell you the ratio and whether it is a limited slip (which would be a Ford Traction Loc). This chart might be out of date but it looks like Ford consistently uses a number as the first digit for an open diff and a letter for a limited slip. Ford Axle Code Chart - Ford-Trucks.com

I know there is a place for older vehicles, but it seems like you are having a non-ending stream of serious and even catastrophic problems (I consider bad brakes to be catastrophic). I like vehicles that go for months and even years without failures and there are 4 of them in my garage (newest one has 97k miles and the rest are well over 120k) so they don't have to be new, just solid. Maybe I'm lucky that in Detroit all the vehicles that are really old are rusted out badly enough that they have been junked.

If you enjoy doing mechanical work, more power to you...but I'm no longer in that mindset.

Good luck,
George

 

Here is a list of information I came across. It is only for 87-90 E150‘s though.
Maybe it will help someone else..

Code-----Model------Year - - - - -Ratio - - RG Diameter - - - - L or NL - - - Spline

S720C - - E-150 - - - 87-90 - - - - 3.08 - - - - 8.8 - - - - - - - - NL - - - - - - - ?
S721A - - - ^ - - - - - - 89 - - - - - 3.08 - - - - - ^ - - - - - - - - L - - - - - - - - ?
S724S - - - ^ - - - - - 87-90 - - - - 3.55 - - - - - ^ - - - - - - - -NL - - - - - - - 31
S730D - - - ^ - - - - - 87-90 - - - - 3.55 - - - - - ^ - - - - - - - - NL - - - - - - - ?
S731P - - - ^ - - - - - 87-90 - - - - 3.55 - - - - - ^ - - - - - - - - L - - - - - - - - ?
S733D - - - ^ - - - - - 87-90 - - - -3.55 - - - - - ^ - - - - - - - - -L - - - - - - - -?

The tag on the differential shows it to be a S724S

 

Thanks for the info YoGeorge.. It is defiantly a NL, non limited slip,, or non locking according to the tag.

I tend to believe it is a bad wheel bearing myself.. I had a friend to stand outside the van while I drove past and he said he could hear a little ting or short squeak as I slowly went by. I thought i heard more of a rotating squeak at times. A bad wheel bearing can cause a tire to wobble too. We will see once i get it out..

You know I have two vans that I have been posting about. A 85 e150 and a 88 e150..
The 88 we are talking about here actually has had just a few problems so far and I believe most are related to it sitting so long, I expected it to have some. Unlike my 85 though, I didn’t just start rebuilding it. I wanted to fix only what was absolutely necessary till I could get few miles on it to make sure there was nothing major wrong with it..
So far the sitting so long problems have been, dry U-Joints, perhaps the axle bearing, and brakes.
The whining sound I believe to be one of the cats. The blower motor cutting off, that im still out on. Adjusting the TV cable was because I didn’t like the way it was shifting. The spliced wires at the dimmer switch were from the conversion company disconnecting the seat belt buzzer. The dome/ interior lights was just a fuse blown from one of the cigarette lighters in the back that had come loose.. (i converted those to USB ports!). The transmission fluid filter change was just routine and the shop screwed that up so i had to re do it... So really I don’t think there has been allot of problems that weren’t expected for as long as it sat.. Time will tell though!

Now my 85,, Thats another story.. It too had sat a while so when I found a leaking rear wheel cylinder, I replaced the whole brake system from the master cylinder on back, drums, rotors, bearings, ect. While I had it up on stands I didn’t like the way one of the axle bearings sounded so I took the rear axle apart and replaced both bearings. While the drive shaft was out I thought, humm, might as well change the u-joints center bearing.. Ect ect.. Then of course the rust in the gas tank so I am just replacing the complete fuel system including carb...

So I guess I do like working on them and I do believe they will both make very dependable vans once I am done.. They are almost the exact same vans so one day I will have plenty of spare parts from one of them anyway! I might make one a camper van...

 

Well, if your problem is the diff and you need a 31 spline open differential, I would seriously send you mine if you are willing to cover shipping. You'd need to confirm that the '02 diff would work in your van; mine is also a 3.55 ratio. The Eaton posi I put in my van is working fine (I just had the pinion seal replaced last year and the shop looked at the diff when they changed the fluid)... I don't envision ever needing my spare open diff (only has 2k miles or so on it). I kept it just because I thought someone might need it someday, or if my Eaton ever failed.

Good luck with the analysis, and get those brakes fixed too...

My first van was a '73 E200 that was a Turtle Top camper conversion (pop top) and my 2nd was an '86 GMC 2500 which was also a Turtle Top conversion. Camper vans are kind of cool but with 2-3 people and our *stuff* they are kind of tight. I did many years of Cub Scouts and Boy Scouts with my vans, but we usually slept in tents (or in cabins in the Michigan winter months).

George

 

Thanks for the offer YoGeorge.. I might take you up on that if i need it.. But you know as soon as you let it go,

Yes brakes are just as important as the axle. no point on going if you cant stop once you get there!

I traded my 95 GMc g2500 for the 88 e150 because the GMC was costing too much and I like the looks of the e150 better.. And the GMC was starting to rust under the paint at the rain gutter on both sides...

Heres my moms 79 e100. Its got a little surface rust on the top and around the gutters but it is not from being rained on. She never drives when it is raining.. It is from the paint fading and moisture while sitting in the carport..
It has always started right up when ever we needed it to... She drives it to town at least once a week and on a 100 mile round trip monthly.. Its a shorty camper..
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Thats 195k and the Windsor 351 is still going strong. I wish i could put a steering wheel like that on mine!!
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I don't think so. The hub is fixed to the shaft which rides inside the bearing. The bearing may make noise or alter the angle of the shaft in the axle if badly worn, but it's not going to change the angle of the hub on the shaft.

I wouldn't jump to the master cylinder either without further diagnosis. You mentioned you looked at the brakes and slid the drums back on. Did you check for proper motion? Are they properly lubricated? Did you remove the shoes and check for binding in the wheel cylinders?

I'd get the brakes figured out before worrying much about the differential. Relatively easy to check though, remove the cover and check visually. If you don't see anything visibly wrong, remove the brake drums and spin the shafts. You should feel if anything is awry.

 

I agree, Thanks


No, I just visually checked the linings and pulled back the rubber on the wheel cylinders to check for leaks. they weren't leaking and the linings were fine. I was thinking master cylinder... But now you mention wheel cylinders, they are steel and after sitting so long, could be rusted inside and the pistons frozen? If I remember correctly the Master cylinder is aluminum. I have never taken an aluminum one apart, I would guess the bore can oxidize as well as the rubber cups deteriorate?
When pressing the brake peddle, one of the wheels slows down and stops while the other continues to roll. The emergency brakes seem to work fine and release all the way, so the cables don't appear to be binding.

Yes, sounds like a good plan.
Thinking about this a bit more, perhaps the rear brakes have not been working since before I bought the van.. If the pistons in the wheel cylinders are rusted in place, perhaps one of them on the left wheel did move out just enough to cause binding when turning the wheel, but not enough to stop it.. That could be what I am feeling when I turn the wheel...

Perhaps there is nothing wrong with the differential or bearings. The wobble in the rear wheel could be the wheel itself or perhaps if the shoes are partially binding in it could cause a wobble?

Bent rim: The kid that did the re-balancing was new and had to get help from someone and only did a visual as the wheel was turning..

Thanks for the suggestions.. got me thinking in a different direction. I will check the brakes first...

1-I will raise it back up on stands and pull the rear wheels.. loosen the brake adjusters and see if I still have the binding..

2- One at a time have someone press the brake peddle while I loosen the brake bleeder on the wheel cylinder. If the peddle goes down and fluid appears to come out the bleeders with some force, perhaps rusted wheel cylinder.

3- slide the drums off half way and look for shoes to move as someone presses the brakes. If they don't expand and retract then could be bad wheel cylinders.

4-check wheel cylinders for rust and seized pistons. If good then has to be master cylinder or proportioning valve..

 

Well some good news! Both wheel cylinders were froze up. The one on the left side was leaking and had some nasty looking fluid coming out of it. Once i replaced then, the binding was gone. While on stands, engine running, and transmission in gear, both wheels turned like they were supposed to. I could stop either and both sounded good. I checked the shafts for play at the bearing and both seemed to be about the same. I swapped wheels from left to right and now I dont hear the whomp, whomp, whomp sound out the drivers side with the window down when driving at slow speeds.

What I am not sure of because lack of experience is, when turning the wheels by hand in park, I can feel a slight bump, bump, bump as I turn each one. Like the gears in the differential. Perhaps that is normal.. With it running up on stands It sounds fine..

I still have a vibration between 60 and 65mphbut believe that is a bad tire or possible bad leaf spring bushings changing the pinion angle.
I am not happy with the Goodyear Wranglers I put on it. They have a deep indent in the sidewall on 2 of them and I suspect one is out or round.. The one i swapped today had 3 oz's of weights on it...