Ford 9inch Rear end problems

gfridland · #1 (**permalink**) 06-01-2003, 06:04 PM

Well, I had a very productive weekend. Finished a lot of small stuff in order to get ready for the upcoming state inspection and upon a very short test drive, things went real wrong. As I was pulling out of the driveway and accelerating lightly, the car lost power, the engine continued to run well, no bad noises. At first I thought it was the clutch letting go and slipping. (The setup is 390FE, tremek tko, hays pressure plate and clutch, ford 9inch with posi and 3.70 gears). I pushed the car back in the garage, jacked it up and was ready to remove the tranny to get to the clutch when it struck me to check the rear end. I spun the wheels by hand and watched the driveshaft, the driveshaft spun when the tranny was in neutral, so i put it into gear and thats when it happened, the wheels spin, but the drivesaft does not. No terrible noises are heard and it feels smooth. It feels almost like the the gears are not messing.

Conclusion: clutch and tranny are fine, rear end is slipping.

The rear end came rebuilt and together with the axles and completely assembled so I never had it apart. What should I look for. Any and all suggestions are appreciated

speed220mph · #2 (**permalink**) 06-01-2003, 06:28 PM

Wierd. Guess the first thing to do is set the parking brake, then try to turn the driveshaft by hand. Stick a long screwdriver in the rear u-joint yoke if you need more torque.

If what you're saying holds true, the driveshaft should turn, even with the parking brake on holding the wheels. This will just confirm things.

To really get to the problem, pull both axles, then the pig from the axle housing. Inspect the ring and pinion, carrier and diff. gears. You should be able to spot the problem right away. Take the center section back to whoever built it and have them correct the problem

I can't wait to hear what the problem turns out to be.

gfridland · #3 (**permalink**) 06-01-2003, 06:59 PM

Set the brake, the driver wheel is tight and connected to the driveshaft while the passenger side spins freely. Is this a limited slip or is there some slip even in a posi traction. If this is true, where is the problem, is there slip in the clutch? It feels pretty good and will not spin when in gear.

Thanks

ted · #4 (**permalink**) 06-01-2003, 08:29 PM

Possibly a short axle in the long tube side of the rear end housing? Could be catching just enough in the carrier to keep it centered but not far enough in to adequately engage in the splines. Might have been just barely engaged before and it's moved just enough or worn to become disengaged.

How about an axle slipping out slightly on its axle bearing and allowing the splines to become disengaged?

Excaliber · #5 (**permalink**) 06-02-2003, 03:54 AM

Doubtful it's the ring and pinion for sure! Man they don't get much tougher than a 9" Ford. Possible broken spider gear set? This of course ASSUMES it is the rear end. The way it broke is very strange indeed for any rear end to go out!

Ernie

trularin · #6 (**permalink**) 06-02-2003, 05:23 AM

Toms right, take the center section back to whoever and have them fix it.

Make sure your have the correct axels for the job.

gfridland · #7 (**permalink**) 06-02-2003, 06:42 AM

With a posi rear, should I be able to spin one wheel by hand while the other does not?

Junket · #8 (**permalink**) 06-02-2003, 08:21 AM

Just a thought 28 spline in 31 spline housing????
Ken

red99z · #9 (**permalink**) 06-02-2003, 09:35 AM

If both wheels are off the ground and you spin one wheel, then the other wheel should spin in the other direction. If it does not then your spider gears were either installed incorrectly or they're broken. If your motor never actually moved the car (i.e. gravity moved it for you) then you may not have any gears in there at all.

Also, they are correct... if you have the wrong axle, then that could be it too. Make sure your axle retaining flange is on too. If its not then your axle can slide out causing your axle to become disconnected from the gears. this can also cause your axle and wheel to totally come out of the differental, your car will then be a three wheel cobra. becareful out there.

gfridland · #10 (**permalink**) 06-02-2003, 09:42 AM

With both wheels off the ground, there is no effect from spinning one wheel on the other wheel. The car did run for about 1/2 mile (easy) before this happened in 1st, 2nd, and 3rd gears and let go in 3rd gear after which all forward and reverse gears were lost. The passenger side rear is completely loose and disengaged from the driveshaft based on how easily it turns as compared to the driver side. There is what seems to be a metalic clutch sound when the passenger whells is spun by hand. I do not think it is the brake rotor sound.

Gene

red99z · #11 (**permalink**) 06-02-2003, 09:49 AM

make sure your axle is retained by the retaining flang. If the axle/wheel is sticking out further then it should (by 1 to 2 inches), then the axle splines have disengaged from the differental and that will cause your problem. If everything is buttoned up tight then more then likely you have damage.

trularin · #12 (**permalink**) 06-02-2003, 09:59 AM

If you drove it say 1/2 mile and then it stopped, and one of the axels has walked out of the housing, you should have felt a drop in the rear of about two inches. There should be a scraping noise and a brake rotor may be dragging.

Check Red99Zs last input and tell us if the axel is out about an inch or two. If so, see if the T-bolts are gone.

You can make new ones from number five or better bolts and a grinder/cut-off-tool.

If you pull the centersection, look for parts in the housing with it out. Let us know what you find.

gfridland · #13 (**permalink**) 06-02-2003, 10:04 AM

The wheel seems to be tight and there does not seem to be any dragging or scraping. I pushed the car back into the garage after towing with a tow rope and a very nervous wife (tow rope connected to car, not wife) Anyway, it felt snooth with the engine off and did not notice any strange noises during the tow and push.

Gene

Mr.Fixit · #14 (**permalink**) 06-02-2003, 11:30 AM

If the driveshaft and pass-rear tire still seem to be connected, the ring and pinion are there. If the driver's rear tire seems completey disconnected from the rest of the drivetrain, either it's splines are not working, or the spider gears in the differential are broken or their cross pin went for a walk.

red99z · #15 (**permalink**) 06-03-2003, 05:55 PM

gfridland,

another thought, If you spin a tire when your in neutral, the drive shaft should spin or the opposite tire should spin. With the tranny in gear, if you spin one tire the opposite tire SHOULD spin in the reverse direction. If this is the case then your rearend is fine, check the clutch or the tranny. (all of the above checking is with the rear tires off the ground and free to spin of course).

Red

gfridland · #16 (**permalink**) 06-03-2003, 07:31 PM

I feel much better. Thanks for all your help.

I put the car on jacks, started the motor, put it into gear and applied the breaks, no additional throttle was neccesary to reproduce the problem and the wheels stopped while the driveshaft was spinning. Had no choice at this point but to pull the axles. Pulled the passenger side out, nothing unusual. Got to the driver side, and voila, about 1/16in of splines missing from the edge and fresh metal flakes. Cause: short axle is too short (5/8inch approx), but just enough to get me up the driveway before letting go. Pulled the center section drained the oil, some metal flakes in it, but not too bad. Anyway it is clean now and ready to be reassembled with correct lenght axle.

Thanks for all your help.

Gene

Excaliber · #17 (**permalink**) 06-03-2003, 07:36 PM

Short axle is to short? OR long axle was put in on the SHORT side! It will work on the short side you know, but the short axle on the long side will barely reach (kinda like what you found)!

Maybe what really happened is the axles got reversed in the first place?

Ernie

gfridland · #18 (**permalink**) 06-04-2003, 07:04 AM

The long axle is quite a bit longer (2-3inches) than the short one and would not fit into the short side. This was a pretty obvious measurement error.

Should have the correct lenght axle hopefully by this weekend and still make the June 20 inspection

Thanks,

Gene

trularin · #19 (**permalink**) 06-04-2003, 08:34 AM

Gene, not that I would think you would miss anything, but, I would clean the insides like an operating room.

Run a magnet over every square inch.

Wash with soap and water, dry completely and coat with 90 weight.

Glad to hear you found your problem. Good luck.