offyourmarks wrote:Nice little vids there pingu
Just out of interest, were you able to 'spot' the damage from within the boot or was the damage only noticable from the underside?
Also - is it much of a job to remove the diff? I have a customer who is a welder and i'm tempted to have him seam weld it as a preventative measure - If the diff comes out/goes back easily enough....
Many thanks
Matt
The major damage, in my opinion, was the ripping crossmember. Catastrophy would probably not occur until many more spot welds failed than the ten I found. However, I suspect the crossmember crack only had to double in length for the diff to rip its mount off.
Only about half of the failed spot welds were visible from the boot and the crossmember crack was only visible with the diff removed.
Warning - the diff is heavy. It weighs 40kg.
To get the diff off...
1. Raise and support rear of car. Both wheels to be free to rotate, but supported at the normal running height.
2. Remove rear exhaust pipes.
3. Remove heat shields.
4. Mark propshaft and diff input flange (Tippex).
5. Gearbox in neutral and remove propshaft nuts (16mm A/F). Rotate the prop by rotating the wheels.
6. Disconnect half shafts (E-12) and tie up out of the way.
7. Support weight of diff at the rear on a trolley jack.
8. Undo the diff mount nut (19mm A/F) and jack up the rear of the diff until the bolt can be removed.
9.
Don't remove bolts before readjusting jack. Lower the rear of the diff (but continue to support it) until you can access the four bolts (16mm [loose fit] or 5/8" [snug fit] A/F) holding the diff onto the beam axle. The diff mount on the rear of the diff will be just below the bottom of the diff mount on the car.
10. Readjust the trolley jack so the diff is supported at the balance point. The jack should also be raised as high as possible, so it can be lowered as the diff is removed.
11. Make sure the diff is properly supported and remove the bolts. They are very tightly torqued and can only be accessed with a ring spanner.
12. You want to try to withdraw the diff from the propshaft in a straight line at the inclined angle, so use a "pull back and jack down" technique.
To refit the diff...
1. Support the diff on the trolley jack and using the "push forward and jack up" technique engage the diff flange on the propshaft studs, remembering to align the Tippex'd mark. It's extremely unlikely that the alignment marks are necessary, but sometimes running gear is dynamically balanced and it's good practice.
2. Put all four propshaft nuts on a couple of threads, but no more.
3. Without raising the car or twisting the beam axle, jack the diff and align the right top bolt hole. I used an angled mirror. Screw the bolt in the hole all the way, then back it off so the spacer can freely turn.
4. Align the diff so the top left bolt can be screwed in all the way. Again, back off so the spacer can turn freely.
5. You will probably have to reposition the jack to raise the front of the diff so the front two bolts can be screwed in tight. Again, back off so the spacers can turn freely.
6. Raise the rear of the diff so the diff mount bolt can be inserted from the rear. I'm planning to put a spacer between the rear lug and the diff mount to reduce the prestress on the rear lug.
7. With the diff correctly supported, tighten all the nuts and bolts to the correct torques.
8. Refit the half shafts, heat shields and exhausts.
9. Lower car to the ground.
10. Wheel spin off driveway
.
by pingu » Fri 28 Jan, 2011 21:27 
1965 Mustang 289 Fastback, 1968 Mustang Coupe 331 Stroker, 1967 Mustang 289 Fastback
