I thought I could wiggle the diff out of the Z without removing the front diff cross member...looks like I am wrong.  I have the car up on jack stands as you can see in the pictures and I can easily remove the front diff cross member by removing the two bolts in the red circles.  My question is.....is this safe or will the car fall on me and kill me?  My concern is that the jack stands are under the control/a-arms as shown in the pix and removing the diff front cross member appears to them leave the front mounting point (yellow arrows) of the control/a-arms loose...this makes me quite nervous as I don't care to die doing this project.  😉

 

Can anyone please help with some info/advice?

 

          

 

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I don’t think that is a safe location to lift the car up, the control arms can bend with too much force on them.

Place the jack stands in accordance to the service manual.

I personally place them below the doglegs there is a spot there that feels secure.

 

a wise friend once told me; “we are going to have to remove it for access anyway, so just remove it.”

Don’t try to skip steps here, you’re only making it harder.

33 minutes ago, texasz said:

I thought I could wiggle the diff out of the Z without removing the front diff cross member.

I went through that thought process myself and even managed to pry the mustache bar around and loosen a bolt here and there to get it out.  But the procedure shown in the FSM is best.  You can go one step easier and just remove the mustache bar also.  I don't know why they don't recommend that way, since then everything is straight up and down.  Load comes straight down, goes straight back up.  The front cross member and mustache bar are good handles for stabilizing the load too.

It's in the RA chapter.

A little tricky of a job though we got it done!  Moved the jack stands as we suggested (and I was suspecting I may need to) and using two floor jacks (one in the back and one under the front cross member I loosened the the front cross member, dropped the front a little bit (maybe an inch), then wiggled the entire thing on both jacks forward until the two rear bolts cleared the mustache bar and lowed both jacks at the same time.  

 

After sliding everything out, removing the cross member from the diff and sliding back up under the Z to put the cross member back in place I noticed how the arms had moved a little bit and was VERY glad I moved the jack stands.  😄

 

Next is to figure out what must be done to get the 3.9 ratio diff to work in the Z.  Looks like replacing the output flanges/output shafts as well as the input are all that is needed so that the drive shaft and half axles of the Z will bolt up.

 

Edited May 16, 20213 yr by texasz

19 minutes ago, texasz said:

Next is to figure out what must be done to get the 3.9 ratio diff to work in the Z.  Looks like replacing the output flanges/output shafts as well as the input are all that is needed so that the drive shaft and half axles of the Z will bolt up.

Which car are you working on?  Funny, but I think that you need an R200 mustache bar so you might as well have dropped it with the diff anyway, if you're replacing an R180 with an R200.  Shouldn't need to mess with the input/pinion shaft flange.  If it's one of the early 240Z's with the diff set forward you might need a new propeller shaft.

Or maybe it's a Subaru 3.9? 

Anyway...there's a solution out there somewhere.  Good luck.

15 hours ago, Zed Head said:

Which car are you working on?  Funny, but I think that you need an R200 mustache bar so you might as well have dropped it with the diff anyway, if you're replacing an R180 with an R200.  Shouldn't need to mess with the input/pinion shaft flange.  If it's one of the early 240Z's with the diff set forward you might need a new propeller shaft.

Or maybe it's a Subaru 3.9? 

Anyway...there's a solution out there somewhere.  Good luck.

I'm working on 8215.  I'm putting an R180 back in.  It is the front diff from a Jan - June 1983 Datsun 720 4x4 pickup.  It is supposed to be a drop in replacement with the exception of the input/output flanges.  I'm going to test that theory.  🙂

 

It is indeed the same R-180 used on the trucks and cars . Swap flanges and go . Good thing is that diff has probably hardly used , and there are some nice low gear sets to be had . 3.90, 4.11, 4.56 

if you drop the front diff crossmember complete with diff attached it will hang of the studs on the moustache bar . Just make sure you break the torque on the moustache bar first . Loosen those nuts to within just a few threads of coming off. Transmission scissor jack from Harbor Freight really helps here 

@madkaw, have you done this swap with the truck front diff?  If so I'd love some more first hand experience/info.

6 hours ago, texasz said:

@madkaw, have you done this swap with the truck front diff?  If so I'd love some more first hand experience/info.

I have not , but own a 83- 720 and have rebuilt it . It’s as easy as you thought. Stub axles bolt in . Pinion flange probably needs to be swapped . Studs on cover should be in the right place 

Just now, madkaw said:

I have not , but own a 83- 720 and have rebuilt it . It’s as easy as you thought. Stub axles bolt in . Pinion flange probably needs to be swapped . Studs on cover should be in the right place 

 

21 hours ago, madkaw said:

 

I have never felt such love for a truck before....

OMG, sweet!!!


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