Sorry I made that clear as mud!

 

Pics

my bar.  its got a factory pressed bush in as standard, you can see either side of the 'lip'

factory bushings...

 

 

diameter

current size of the hole

 

pressed in bush thickness

 

 

So, on earlier cars, the bushing was rubber outer that pressed into the factory fitted metal flange/bushing.

So it seems, I need to cut one end of the curve off, then press out the rest, before fitting the newer design(1971?) in.

Can i use my early straight bar, just flip it around to use with the later lower diff mount?(curved one).  Is there an actual issue with early ones?

11 minutes ago, Jason240z said:

So, on earlier cars, the bushing was rubber outer that pressed into the factory fitted metal flange/bushing.

Is this correct? I haven't heard of this. Your existing bushing looks like a bushing that has had the rubber core removed and cleaned up. Most of the time these have poly bushings installed in them. If you want to use the new bushing you will need to remove the old bushing shell from the bar. Press the new bushing in and flare the edges. I know someone that has flaring dies but I am not sure they are available for use internationally. You would need a hydraulic press to flare the ends. You might be able to get some dimensions for how to make the dies and have some made locally for the same amount of money for the shipping and import duties.

On flipping the bar, I don't know

That's exactly what I thought you were describing.

So to me, it looks like someone has removed (burned, grounded or something) the rubber portion of the bushing and left the outer metal shell installed. In other words... That looks like the two flange bushing style that someone has eviscerated, presumably in preparation for installation of poly bushings.

I believe the process would be to cut (or peel up straight like a banana) one of those flanges off and then press the bushing remnants out of the bar. Once you do that, you should be able to press the new ones in.

18 minutes ago, Jason240z said:

So, on earlier cars, the bushing was rubber outer that pressed into the factory fitted metal flange/bushing.

Yeah, I'm no expert on the bushing lineage, but I'm not so sure about that either. Have you seen a picture of that kind of bushing?

on further investigation, the insulator bushings are over length, so they should have a return lip pressed in once fitted to the bar, like they did at the factory when new.....

I was leading myself up the wrong path thinking that there was an earlier design.  The cars were just well made it seems.  However none of the manuals seem to mention it.

The PO did fit a polybush.  The rest of these i've given away!

I found one of the old threads/articles about that custom tool.  Click the arrows to go back and forth, it's a pictorial.  Search the name and you might find more.  Somebody was loaning one out for a while.

 

On ‎3‎/‎18‎/‎2018 at 10:37 AM, Namerow said:

Kudos to Kats for being able to finally produce for us a well-organized set of clear photos and graphics, c/w parts numbers.   I still have a few questions, though.

1. The M-bar mounting/isolation scheme for the Early S30's with the angled halfshafts (SoP to until 71-06) appears to use a unique isolator design, in which the rubber core extends out around the lower end of the metal outer shell so as to provide a soft lip for the plain-metal-washer lower 'stopper' to sit on.  This apparently didn't work very well  (the rubber lip probably sheared off over time).  Does any one have a photo of this early-version isolator (PN 55476-E4100 or 55476-E4101).
2. In the section view of the early-version isolator, the clearance gap marked as 'A' is intriguing.  In the FSM, it's called 'B' and comes with the following explanation: "Replace differential mounting rear insulator if the dimension 'B' is less than 5mm."  I believe that the lower 'stopper' (washer) is supposed to sit on the hard stop created by the square step machined into the bottom of the tapered mounting stud.  Then the securing nut gets torqued to 60 lb-ft.  The lower stopper doesn't even touch the insolator.  So that means that the 'A' (or 'B') gap is intentional and the hanging weight of the Diff would be entirely taken up in shear by the rubber core of the insolator.  This would be quite different in principle from the later style arrangement with the rubber-faced lower stopper.  In that later design, the hanging weight of the Diff would be taken through the rubber stopper and into the tapered mounting stud.  Makes me wonder why they even retained the rubber core for the isolator in the later design.  Comments, anyone?


3.  

This would have been a good thread for me to have read back in 2005 when I replaced the isolators in the mustache bar on my 7'70,  Here is a picture of the old isolator, early style, beside the box from the new, later style, replacement that I was able to get at the time. The picture of the newer style one installed shows the extension that should have been formed into a flange, oops.  The picture also shows the gap 'B' is very evident.

 

The old single flange design would be a lot easier to replace (because you just press the old one out and press the new one in. The later two flanged design is a little more involved. This is what I did.

First, I cut a bunch of slots in one of the flange ends with a thin cutting disk:

Then, using a couple punches and a hammer, I peeled up the "petals" of the flanged lip. Worked my way around the bushing:

Once those petals were peeled up, you can push the old bushing out of the bar and press the new bushing into place.  No pics should be required for those two steps.

In order to form the second retaining flange on the new bushing, I made a pair of press forming dies for the hydraulic press. Here's a pic of a new bushing and the dies I made. I made two dies to form the flange in two steps. First flaring step is a simple taper (on the left), and second step flattens the lip after the taper die has bottomed out:

Here's another view of the dies. Preliminary taper form on the left, final form on the right.:

Once the new bushing is pressed in place, I used the preliminary form to flare the metal outward:

And then once the flare was formed, I switched to the final form die:

And finished the flare flat into the retaining flange:

 

Hi Captain !! You are the best engineer for helping others , I wish I can do it for my cars like that . 

Kats

5 hours ago, Captain Obvious said:

The old single flange design would be a lot easier to replace (because you just press the old one out and press the new one in. The later two flanged design is a little more involved. This is what I did.

First, I cut a bunch of slots in one of the flange ends with a thin cutting disk:

Then, using a couple punches and a hammer, I peeled up the "petals" of the flanged lip. Worked my way around the bushing:

Once those petals were peeled up, you can push the old bushing out of the bar and press the new bushing into place.  No pics should be required for those two steps.

In order to form the second retaining flange on the new bushing, I made a pair of press forming dies for the hydraulic press. Here's a pic of a new bushing and the dies I made. I made two dies to form the flange in two steps. First flaring step is a simple taper (on the left), and second step flattens the lip after the taper die has bottomed out:

Here's another view of the dies. Preliminary taper form on the left, final form on the right.:

Once the new bushing is pressed in place, I used the preliminary form to flare the metal outward:

And then once the flare was formed, I switched to the final form die:

And finished the flare flat into the retaining flange:

 

Thats my plan also, i think 2 stage is the way to do it.  

Think it would work with a single though?

5 hours ago, Jason240z said:

Thats my plan also, i think 2 stage is the way to do it.  

Think it would work with a single though?

Well I wasn't there at the factory when they were swaging those bushing, but I suspect they did it in just one step. Keep in mind, however, that they have access to machines and processes that I don't. I'm also sure they heat treated their dies, and I did not. I started with a mid-hard heat treatable steel that I could heat treat to a very suitable hardness, but I figured I'm only going to be doing this a couple times, and even without the heat treat, my dies should outlast me.

So IMHO the bottom line is that I think it's possible to do it in just one operation, but I wouldn't recommend it unless you really know what you're doing (and I do not).

However... After going through this, I believe that I can simplify the die design. You see... The first flaring die did such a fantastic job of tapering the material outward that the curved section of the second did never even made contact with the bushing wall until the flange was pressed completely flat.

In other words... The complicated portion of the second die (the carefully radiused and polished center section) is pretty much unnecessary and that second die could look just like a donut with a hole in the middle. That raised portion isn't even necessary. In fact, I believe I could have simply flipped my tapered first die over and used the flat side to press the flange to it's final position. I think that if designed properly, you could get two forming operations from two different sides of the same die.

So, if you're looking to minimize the cost of having dies made, I would try that.

Here's a pic at the very start of the first tapering operation:

And here's how it looks fully tapered with just the first die. You can see that the material is "rolled outward" so far already that it never even contacts the curved portion of the second die:

If I had known that a the beginning, I may not have even made two dies. I may have made one "reversible" die instead and saved myself that polishing time.

7 hours ago, kats said:

I wish I can do it for my cars like that .

Hi Kats, Thank you so much. I'm humbled and honored and I'm just trying to help out where I can.