9" rear end failure

Well I took the first road test in the El Camino this morning, made it about ½ mile and ended up bringing it home on a tow strap.

I was taking it very easy on the truck, checking to make sure the transmission shifted ok etc. Everything started out great until I went around a corner the truck down shifted and all the sudden there was a small pop and a whining sound and forward movement stopped. It felt like the transmission was suddenly slipping badly. You could feel it try to kind of pull in both low and reverse but it was not able to overcome even a very slight slope.

Fortunately a friend of mine was around and towed me back to the shop. What we found when we got it back was that the drive shaft was turning but the wheels weren’t (on the bright side it at least it beats having to R&R the transmission).

The rear end is a 59 Ford SW 9” It was a complete drum to drum pull out that originally had an open 3.50 carrier in it (as it was already out and all I was going to be re-using was the housing, axels and brakes I there was no chance or need to road test it). The differential is one I picked up from a friend and had rebuilt prior to installing it. It’s a 2 pinions Traction-loc differential and 2.75 gears.. As I said there were no loud noises, grinding or jerks and popping when it stopped working like I would have expected if I had knocked some teeth off something.

I pulled the third member out and tore the Traction-Loc apart. Other than the clutches being kind of ugly now there is no obvious signs of damage; no broken teeth on the ring and pinion or spider gears, no chewed up splines on the axels and the axel bearings are still fully seated.

I’ve been around Posi units with burned up clutches in the past and they basically just act like an open rear end, this one doesn’t will barley move the truck on level ground.

Has anybody else run into this before and have an idea on what’s not right?

. About the only thing I can come up with it one or both of the axes are too short and only engaging the clutch hub (thrying to transfer all the power thru the clutches) and not the spider gear(s). I’ve never heard of different axels between posi and non-posi units…..but I suppose it is possible that at some point one or both axes have been changed in the 40 years since this axel was built.

put the axles back in the housing measure the gap they it should be around 1 1/4 if more then the axles are to short . if you do not want to do that shove them in to the pig and measure were the bearing seats in the housing and measure over all housing should be close . if you freind re built the limted slip and did not line up the limted slip drive hub to the side gear the axle on clutch side will not engage and you may have had the axles right to left mix up as there is one long and one short .sounds like to me you were driveing just a the clutch pack pressure that why the look so bad and not thru the side grears working the spiders so axles were to short or the axles were mixed left to right

use some bluing or a marker or one line of masking tape 1.250 inch from the end of axles spine you need to drive the carrier more is better should see the wear marks on the spines but thats off the top of my head . this will also tell you if your all the way in on clutch side . i allways built the posi with a stub i made up from old axels that i chop down and welded a 1by1 pc of tube to look like a T and clamp the 1by 1 in the vices so when i built the posi up.i always the pack and side gear were line up

Thanks Pat. I agree with the comment about just driving on the clutch pack pressure by the way it acted and sounded.

The axels weren't mixed from side to side (first thing I checked). I think I'll start by shoving the axels and measuring the the gap. I've still got the unit apart and really don't want to re-assemble until I can figure out what went wrong.

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Originally Posted by Mike P

Thanks Pat. I agree with the comment about just driving on the clutch pack pressure by the way it acted and sounded.

The axels weren't mixed from side to side (first thing I checked). I think I'll start by shoving the axels and measuring the the gap. I've still got the unit apart and really don't want to re-assemble until I can figure out what went wrong.

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you do not have to re assemble all of it. put the axles in the housing with out the pig look at the air gap .or stuff the axles in the pig on the floor or table and measure from bearing race to race were it seats .now measure the housing this will tell you if the housing to long . the tape or marker is to check the the axles are all the way in this is how i did it when guy pick up axles at the swap meets and wanted me to cut a housing down . there no way you can run on just the clutch pack if the axles are the right size

is there a sping pack in the carrier ? four pins are way better and you still can get some rebuild parts for they have a steel cage and use 4 springs . yours could have the same cage just not cut out for the other pin and still take for 4 springs . the very old ones took a spring in a spring only seen one time could not get parts for it so i am fuzz on that one but even if clutchs were gone you would still get the one wheel deal your axel is to short . who put the wheel bearing s on ? did they put the wedding ring on first ? then the bearing. drums would hand out a bit from the backers but not much they over lap any ways ??????? that would do it to

"........is there a sping pack in the carrier ? four pins are way better and you still can get some rebuild parts for they have a steel cage and use 4 springs ........"

Pat this is pretty much what the internal parts that I have look like less the clutches and of course only 2 spider gears.

http://cgi.ebay.com/ebaymotors/31-Sp...item3f05fdb920

I did the axel bearing and yes they were assembeled bearing first and then the lock ring.


"..... but even if clutchs were gone you would still get the one wheel deal your axel is to short......."

I keep going back to that Pat, The only thing that makes sense to me is that one of the axels is just long enough to engage thru the clutch hub but not into the side gear ( I can feel it engage the carrier and can't turn the wheels with it in park). That's only explination I can come up with that would explain the truck acting like it was trying to move but act like a badly slipping trans.

the space on the axles should be a bit more then the cross pin I.D or clutch spring block what ever hits first . the posi side of the clutch drive hub is first and side gear set last on this side so around 1. inch air gap or a abit more but 1 7/8 may be a bit big of a air gap . that why i always mark axles spines. then i could check engagement measurement of the spine pull them out a 1/8 or so they did not bottom out on cross pin when wheel bearing was seated. Mosser did most all the re spine or new axels for me so they knew what the air gap needed to be. but on used stuff like axles with out housing you have to work all this out alot of measuring i have not played with one in sometime ....old timmers

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Originally Posted by Mike P

"........is there a sping pack in the carrier ? four pins are way better and you still can get some rebuild parts for they have a steel cage and use 4 springs ........"

Pat this is pretty much what the internal parts that I have look like less the clutches and of course only 2 spider gears.

http://cgi.ebay.com/ebaymotors/31-Sp...item3f05fdb920

I did the axel bearing and yes they were assembeled bearing first and then the lock ring.


"..... but even if clutchs were gone you would still get the one wheel deal your axel is to short......."

I keep going back to that Pat, The only thing that makes sense to me is that one of the axels is just long enough to engage thru the clutch hub but not into the side gear ( I can feel it engage the carrier and can't turn the wheels with it in park). That's only explination I can come up with that would explain the truck acting like it was trying to move but act like a badly slipping trans.

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do not ask me how i know if the axle to short on the clutch pack side.and not in the side gear the car will not move:( but you may have hook just a bit. blue it see how far its going in it needs to be all or better then a 1inch

pig still in car ? if so pull axle out run a tape measure down the tube should feel it hit then lift up and should go in 1 1/2 more or so read at bearing seat now measure the axle from bearing seat to tip of axle .if you do not want to blue the spline

"......pig still in car ? if so pull axle out run a tape measure down the tube should feel it hit then lift up and should go in 1 1/2 more or so read at bearing seat now measure the axle from bearing seat to tip of axle .if you do not want to blue the spline"...."

The pig is still out and apart, but I was just sitting here thinking about doing exactly that .

well then go back and do post #2 and 5# and see what you have:)

if you have 28 spline axles did someone put a 31 clutch hub in the posi.if that is a 59 rear end i did do up a 59 for a 34 ford with a 4 spider posi axles work off the newer posi and a 60 bronco with a newer 4 spinder posi one may have had new moser axles and a 37 ford never remember a axle deal but that was 12 years ago and i was deep in to them i stop doing alot of them when most of my customer went to bikes

as I read down thru here I was wondering about the 59 axles being 28 and possibly differential a 31 spline

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Originally Posted by jerry clayton

as I read down thru here I was wondering about the 59 axles being 28 and possibly differential a 31 spline

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yep i said that on my last post or more or less:D not sure if you could get the28 to grip 31 is abit bigger

[QUOTE=Louey;411108]Sounds like a short pin fell out. If so, the spiders would walk around, but no pull.
If nothing else, recheck that center section.[/QUOTtwo spiders have only a long pin one end is lock in with a roll pin . the pin can not come out on a ford posi less there a lot of busted parts

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Originally Posted by Louey

I have no idea ??? Just throwing more in there.

It’s a 2 pinions Traction-loc differential and 2.75 gears..

I pulled the third member out and tore the Traction-Loc apart. Other than the clutches being kind of ugly now there is no obvious signs of damage; no broken teeth on the ring and pinion or spider gears, no chewed up splines on the axels and the axel bearings are still fully seated.

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yep the pin can not come out with the ring gear on . there a set up on the clutch pack with a ford tool or make one like i did . many do not check this or shim up the clutch pack .so they can burn out fast . i am not shure you if you can still get the shims thru ford . the springs can go weak as well i allways put new springs in . last time the ford dealer said i could not get springs any more . some stuff could be pick up thru DTS and others but was not a lot. not letting the clutchs set soak in oil his hard on them to

It sure sounds like the axles (or just one axle) are not engaging the spider gears, just the clutch packs. Did someone put a 31 spline gear in the diff with the rest 28 spline? That would do what you are describing.

Stock axle length on 57 Ford rear I bought was 26 1/16" and 30 7/16" with 1 1/8" gap measured between axle splined ends.

Deuce4papa, where were the measurements taken from.....i.e. the splined end of the axel to (innere edge of the flang/outer edge of the flange/or total legnth counting the hub index (the raised portion the that center the brake drum)

As far as 31 vs 28 spline, that was checked by me prior to assembling the rear end.

Well, I think I found the problem, I went to re assemble the carrier so I could start to take some measurements..........the side gear is 31 spline. When I took it apart yesterday I was primarly just looking broken parts and I overlooked that.

It looks like I'll get away with a set of clutches and a side gear to get it back together.

Thanks everyone, (especially Pat) for helping me brain storm this......I will still be measuring the axels before it goes back together again.

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Originally Posted by Mike P

Well, I think I found the problem, I went to re assemble the carrier so I could start to take some measurements..........the side gear is 31 spline. When I took it apart yesterday I was primarly just looking broken parts and I overlooked that.

It looks like I'll get away with a set of clutches and a side gear to get it back together.

Thanks everyone, (especially Pat) for helping me brain storm this......I will still be measuring the axels before it goes back together again.

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yep thats what i was thinking. if you need a 28 let me know. the clutch side i think you can only get in 31 new or that the way it was. i have cut down 28 s opens for clutch side you only have to face the shoulder off not all of the face of the side grear to get it to work and thats good it hard . if i can help any more PM me and i see if i have any parts around for you .if you can not find any i know i do not have the 28 clutch hub that may be hard to find side gear not so much

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Originally Posted by Mike P

Thanks everyone, (especially Pat) for helping me brain storm this......I will still be measuring the axels before it goes back together again.

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A trick to visualize depth that I've used in the past is to find an O-ring that fits the splines snugly. Then insert the axle (in this case) and then remove (carefully) to see how much spline is showing. My point oh two!:LOL:

Thanks for the offer Pat, The clutch hub I have is 28 spline which is why I didn't realise there was a problem when I put the rear end together. I found a NOS 28 spline side gear on E Bay and the clutches should not be a problem.

Mike. I measured from wheel mounting flange face to end of spline. I hook the tape through the hole in the flange to get a good measurement. The SW should have had the 31 spline axles, but it is what it is. Currie may have the traction lock disc.

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Originally Posted by deuce4papa

Mike. I measured from wheel mounting flange face to end of spline. I hook the tape through the hole in the flange to get a good measurement. The SW should have had the 31 spline axles, but it is what it is. Currie may have the traction lock disc.

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There were NO 31 spine axles until 1963. The first ones were in the 427 63 1/2 Full size with 427 engines.

yep o rings is a great idea other then it will not work in this case as the o ring is just going to get push down the axle for a false reading. as the carrier side bearing shoulder about 1 inch from out side of the side gears .I.D of the axle hole were the side bearing ride is not much bigger the the axle 28 or 31 O.D and O rings will get hang up when you push the axle in masking tape works the best is you tap a 1 inch down and if you do not hit it you axles are to short

yep clutchs are not hard to get yukon sell them as many others . i think there some on e bay .

"There were NO 31 spine axles until 1963"---- MY mistake! Thank you for correcting. Good info to know. It was not my intention to mis-inform Mike. Thanks again

I had a similar problem in a ford 9inch after swapping rearends and my yoke was the issue,it was spinning on the pinion,swapped gears but used the old yoke and the splines were not correct,cost me a new set of gears and a yoke unfortunately. Just an FYI.