Proper install of front differential mount

[ezzzzzzz]

I have started installing my rearend. The diff is in and I installed the front mount with the bolt hole offset (the bolt holes in the mount are not centered)to the rear because things lined up better. Now, the lower drain plug is in contact with the rear crossmember. Come to think of it I also had the remove the torque strap because it was right above the bolt heads. The main purpose of this was to relocate the diff back 1 inch to correct the early design problem. Did I screw up? I'm guessing I did the more I think about it.

[jmortensen]

When I went to move mine back I bought the later style link behind the diff that has the curve in it. After I did that I read on the net that you can move the diff back and still use the straight link behind the diff. Your experience would show otherwise...

I moved the strap back by moving it back an inch also and attaching it by the front bolts on the strap mounts to the last 2 holes in the chassis. You have to grind a little bit to get it in that way (very minor grinding takes 2 minutes), and I ran mine for a couple years like that and had no trouble with the mounts coming loose or anything like that.

I finally decided to get rid of the strap entirely, so next time my car drives it won't have a strap anymore. Search front diff mount and you'll see some very easy modifications are possible that eliminate the strap completely.

[ezzzzzzz]

I could pull mine and do a little metal work. The plug is about three threads out. Maybe I could just grind it down. How about a spacer between the rear crossmember and diff to move it forward enough to use the front mount as shown in the FSM? I planned on eliminating the strap and fabbing a torque restrictor that goes under the front crossmember.

[ezzzzzzz]

I'm too tired. It just occured to me that if I install the front mount reversed that I'm right back where I started and the rear diff support would have to bow forward. I guess I'll have to cut away at my beautiful powdercoating. :tapemouth

[beandip]

Ez , are you installing a R-200 into a 240 ? If so , you do know , I hope , that you need the r-200 M bar + the bar is mounted in reverse to the 240 bar. this mounts the diff. pumkin to the rear just far enough so the drive shaft and all connects with out problem . the straps should not be a problem either , all should line right up. Gary

[ezzzzzzz]

I'm installing the R180 LSD that came in the car. I keep wondering about that strap and the drawing depiction of the rear suspension. It clearly shows the front diff mount installed with the holes forward. This may be due to the original flat rear diff mount though. I'll instal the driveshaft shortly. If it goes in without a problem then I know I'll need to mod the rear crossmember.

One more observation...the lower drain plug is inaccessible without removing the rear crossmember. Is that correct? Damn, I wish I'd taken pictures prior to disassembly! :stupid:

[jmortensen]

I think you have it right ezzzzzzz. Beandip is thinking R180 to R200 conversion. The diffs are the same length so the strap should line up similarly. What he's missing is that you're moving the diff on an early Z to correct the driveshaft angles.

Like I said before, I think the curved link behind the diff from a 72-78 is the way to cure your ills.

[ezzzzzzz]

That's the direction I'm taking. I am still curious how the strap is installed in later Z's with the diff moved back. Maybe the mounting holes are located further back as well?

[jmortensen]

That's right, because the diff was installed further back.

[=Enigma=]

When removing the diff on my '73, I noticed that the strap was not inline with the area it should obviously be lined up with on the diff. The strap actually rubs against the rear edge of the front diff bolt housing. In other words, the strap is actually bent to the rear in order to sit in the intended groove. I guess they moved the diff back but left he strap in the original position. I wonder if I can move it back. guess I'll find out when it's time to put it back in.

[ZSaint]

I put an R200 in my '71. I did not relocate the diff. It is still a bit forward of "perfect". I raced these things for a long time w/o any problems. Why do I need to move the diff back in line with the CV axles? It is a street car. Why?

[jmortensen]

I put an R200 in my '71. I did not relocate the diff. It is still a bit forward of "perfect". I raced these things for a long time w/o any problems. Why do I need to move the diff back in line with the CV axles? It is a street car. Why?

Did you redrill the R180 mustache bar? Because if you used the R200 bar that in itself moves the diff back.

If you're running CV's then you don't need to move it back at all. Take a look at any 911 and you'll see that CV's can handle the misalignment with no problem.

I've only been around/driven 4 early 240's, 2 of them were daily drivers (one mine) and had the diff moved back and the other two were not, yet the ones with the diff in the original position experienced broken U-joints in the short time that I was around them.

My opinion with my limited experience is that if you're going to drive your car hard, even on the street, its a good idea to move the diff back if you're using U-joints.