Lately I've been noticing something a little weird. When I reverse, I feel a bit of a muffled clunk coming from the back end. And when I'm accelerating and backing off sharply in 1st gear, I feel it again.
In the Hako, the front of the diff is hardbolted to the suspension subframe, and the back of the diff is supported by this transverse bar called the Moustache Bar, for obvious reasons. I was thinking that maybe the bushings in the ends of the moustache bar were gone, and so the back of the diff is thudding up and down against those rubber snubbers as it reacts to the torque of accel and decel.
Datsunfreak (Technical Editor John Roper from the magazine) reckoned that the end of the moustache bar isn't meant to be sitting on the lower snubber like that, and is meant to be more like in the middle. So it looked like those bushings have to be replaced.
Getting the moustache bar off wasn't easy...unbolting it at the bushing end is easy, but it locates to the diff via these two studs, and so the protruding studs prevent you from dropping the bar down vertically. Unbolting the front of the diff to ease it fwd's so that the studs can slide out seemed like the hard way to do it, so I decided to try to unscrew the studs by locking two nuts together, and unscrewing the inner nut. The steel stud was pretty corroded to the alloy diff casing, so this part was a bit of a pain, as it was one of those things where it was really tight to unscrew, bit by bit all the way.
But in the end the bar's off...
And on closer inspection the bushes do look a bit ruined, the rubber has torn clear of the metal crushtube in the middle.
To remove the bushes, first we cut off the rubber lip that mushrooms out on one side.
And for the next step, say hello to my little friend
It's a 6ton hydraulic press! Basically it's just an upside down trolley jack, as you pull this lever, the piston comes down, and there is a beam and some sturdy metal plates below to brace things against. It's not a very hi-quality one, and was inexpensive (some might say...super-cheap
, even..aussies will get this
) but I figure I'm only going to use it a few times a year to press out a few wheel bearings and suspension bushes, so it didn't make sense to buy a really expensive one.
Take a closer look, and the bushing (yes I pushed out the centre tube just for fun) has a few concentric metal tubes. The outer one is the bushing's outer metal jacket, and the inner one is the one we will be pushing out.
Brace the moustache bar carefully in the press, and then pick a socket that's just the right diameter to push on the metal tube of the inner bush. You'll notice that I've got clamps holding down the metal plates under the 'bar...when you're working, everything's under tremendous pressure, so the clamps are to prevent the plates from slipping out and flying across the workshop, narrowly missing your head (um...appparently).
The press makes light work of pushing out the inner bush.
What's left is the outer bush jacket, which is in 2 pieces, so it's easy to tap out with a chisel and hammer
...the remains of the diff bushes.
Then I cleaned up the inside of the tube with a wire brush
And the new poly bushes (from SSS Automotive) just press in by hand.
The rejuvenated moustache bar in place! You'll also notice that I didn't put the stock diff studs back in place, but I used bolts instead. So the next time, I can just take out the bolts and the moustach bar will just drop down, which will make diff removal easier too. (This was also a Datsunfreak suggestion)
...and that's where we're at...I'll see how she drives tomorrow, but I'm sure it'll be better than it was...
No Kev, you are eating a duck fetus.