Project Theseus

[Noll]

Got a free R160 today; person who gave it to me said it was locked up and couldn't remember the gear ratio. In the end it just ended up that the input dust shield had rusted to the housing, spun it with an impact and it's like butter now. Even better, after popping it open it's a 3.9:1 diff, which was exactly what I was looking for (and conveniently the ZX 5spd I have already has a speedo gear for a 3.9).

Cleaned it and the old R180 up a bit so it'll be a less messy job to swap parts over (it'll get paint too ofc):






I then pulled the old diff apart to confirm the ratio (like I thought, the stock 3.36:1 or whatever) and get a better idea what the diff buttons look like that I'll need to swap.








All the info I've found about the internal swap has been little bits and bobs from various forum threads scattered all over the internet, and no one "how-to" writeup, so I think I may as well make one to help people out in the future. My Z stub axles are the correct spline count for the subaru diff, so it should just be a case of figuring out how to get the spider gears out of the R180, swapping the threaded "buttons" over, and swapping the driveshaft input flange over to the R160 as well.

Just need to do a bit of research as to how the spider gears come out, and the rest should be a piece of cake.

[Noll]

Did the diff parts swap today, went great. Info below, if anyone thinks it's worth its own write-up (as all the info about it is bits-and-pieces in old scattered forum threads throughout the internet) I can do one with torque specs etc. It's not a complicated swap to do by any means.

Pulled the diff cover and side plates off the Z R180:






On this diff, the pin that holds in the main crossrpin is peened into place. Tapped the hole round again and drove it out with a drill bit:






The ring gear stops the pin from coming out, so pulled that off and slid the pin out.






Tapped the buttons out and reassembled the diff. Didn't bother with torque specs as it would need to come apart again to be used (to put the buttons back in) anyway.





on to the R160, had to pull off the diff breather to get at one of the bolts:




marked the side plates before removing, so as to not mess up the number of shims or the orientation:




In the subaru diff the pin holder is a rollpin, easier to remove than the other diff.






Marked the ring gear and carrier before unbolting:




Took the crosspin out and rotated the spider gears so I could take them out:






Removed the old circlips by squeezing them in then dremelling it in half, too much spring tension for me to remove it otherwise with the tools I have:




Buttons onto the side gears, required a decent amount of force with a hammer to push them into place. Clearance is tight but it's there.






Put everything back together, and swapped over the driveshaft flange, as well as the rear mount studs (not pictured):




And complete and axles bolted on. Obviously I still need to clean and paint the diff and axles (as well as possibly new gaskets for the diff), but it's a 100% bolt-in setup as it is right now.




3.9:1 rear and the 5spd should be a nice combo .

[DAT240]

Nice work! I was lazy and found a 3.90 R200 but still opened it up and changed the oil seals, bearings, checked the teeth. Of course that meant changing suspension bits like the moustache bar etc. to match the R200 so it is probably a trade off. The R200 setup adds weight as well. I also got a case of the "you might as well" and refreshed the half shafts that came with the R200 (new boots, cleaned and greased - found no issues but gained peace of mind) and changed the U joints. I recommend replacing the U joints - they're a weak link and it's an easy job once the half shafts are out, but that's probably on your list. I'm watching your build with great interest. Really cool.

[DAT240]

Looking at your posts from a couple of days ago -
muffler hanger.jpeg
Yes, this is a muffler hanger bracket - I just removed the old hanger a couple of days ago.
vent hose?.jpeg
Can you tell me what this bracket is for? I'm guessing that the fuel tank vent hose (from the expansion tank to the valve in the engine bay) routes through here but can't be sure.

I'm finding that the little details take time to solve, especially where hoses and brake lines route. The hidden ones are the worst - not shown in the manuals that I have and not featured in internet photos.

[Noll]

Looking at your posts from a couple of days ago -
muffler hanger.jpeg
Yes, this is a muffler hanger bracket - I just removed the old hanger a couple of days ago.
vent hose?.jpeg
Can you tell me what this bracket is for? I'm guessing that the fuel tank vent hose (from the expansion tank to the valve in the engine bay) routes through here but can't be sure.

I'm finding that the little details take time to solve, especially where hoses and brake lines route. The hidden ones are the worst - not shown in the manuals that I have and not featured in internet photos.

Thanks! A r200 would have been nice, too, but as you say there is more weight there and pricier to get all the bits needed. All my u-joints seem rock solid with no play (and indeed they seem to be the non-replaceable type at first glance), so I'm just going to clean them up and run them as is for now; worst case I have a CAA membership .


As far as I am aware that bracket is for the hose that leads to the filler neck to allow air to escape the tank while pumping gas; where it goes after that bracket I'm not sure offhand; could be either of the two paths I marked. There are a couple FSM diagrams of the fuel/vapor hose routing out there on the internet, so I plan to follow them as far as what connects to what and just route everything as neatly as I can within that constraint.

[DAT240]

Thanks for the photo - another mystery solved.
I found this photo of the routing for the brake lines - it confirmed what I was doing. Of course, I can't just follow instructions. Ditched the brake system failure warning switch (unnecessary, just like rear view mirrors) put a manual proportioning valve for the rear brakes in its place.
1972_datsun_240z_master cyl.jpg

[Noll]

Thanks for the photo - another mystery solved.
I found this photo of the routing for the brake lines - it confirmed what I was doing. Of course, I can't just follow instructions. Ditched the brake system failure warning switch (unnecessary, just like rear view mirrors) put a manual proportioning valve for the rear brakes in its place.
1972_datsun_240z_master cyl.jpg

No problem! If you need any more pics of the brake/fuel lines let me know, I knew I wouldn't have a hope in hell of remembering how it's supposed to be routed so I took a few pics when I tore the engine out. I may also delete that warning switch, from what I can see from a diagram of it it doesn't actually block fluid of one side has a leak, it just throws a light on. Will confirm before I decide.

I won't be adding a proportioning valve though, Grannyknot mentioned a while back that my brake setup (that I got from him as he upgraded to Silvermine parts IIRC) is better balanced without one at all; after all all they can do is limit flow, not increase it to the other circuit. He had better results without one than with a wilwood one he had had in the system for a while, so that's good enough proof for me. toyota 4x4 calipers up front with the bigger 300zx vented rotors, maxima/240sx in the rear.


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Back to welding today, made some jack points in the middle of the rockers to more easily so stuff where the whole car doesn't need to be lifted (don't want to have to take the front spoiler off to get at the front xmember jack point etc).

Started with a brace plate:




And the actual jack point:




Welded it all up and boxed it in. I intentionally ran those welds along the sides to act as a safety measure against a jack sliding off the side of the plate somehow.




Also welded a reinforcing plate to the rear seatbelt buckets - more than anything this will ensure that the water drain section won't get crushed if this is used as a supporting point if the car ever goes up on a lift.




I think that's about it for jack point reinforcement unless anyone can think of something I should add. The front jack points are the frame just behind the t/c boxes, or the front crossmember, and the rear ones will be the rear diff, rear diff crossmember, the above seatbelt mounts, or the subframe just behind them.



Next up, on to front bracing, and then I might be done as much as I can with the car flipped this side.

[DAT240]

The jack point looks solid, very nice. I have never used the jack points on the sill - my car would have crumpled.
I looked at my original jack - it appears that it is made to fit with the seam of the sill down the middle, likely so that it won't slip.
Here's my jack:
jack pts.jpg
and the instructions from the manual in the glove box:
jack.jpg
Your setup looks much more solid.

[Noll]

The jack point looks solid, very nice. I have never used the jack points on the sill - my car would have crumpled.
I looked at my original jack - it appears that it is made to fit with the seam of the sill down the middle, likely so that it won't slip.
Here's my jack:
jack pts.jpg
and the instructions from the manual in the glove box:
jack.jpg
Your setup looks much more solid.

Many thanks, and thanks for the pics! Like you I don't really trust the stock rocker points, even though my rockers are 100% new metal at this point. My plates are still putting load on the rocker of course, but with the internal upright welded in it should be pretty evenly spread between the inner rocker, outer rocker, and the (much thicker metal than stock) floorpan, as well as being pretty close to the seat mount crossmember inside the car. Shouldn't need to use it too much, but I think it'll hold up.

Dunno if it'll be neessecary as the place I go to for safety inspections for my cars is pretty chill (and they know I've been working on this thing for 4 years and will have redone everything), but just in case they need to put it on the lift I'll be marking 4 good lift spots front and rear with paint and making sure they know to only put the lift pads there. Don't want to deal with crushed rockers right after painting the car.

[zedfoot]

Mine is new metal, but not reinforced like yours. I cut notches in 2 x 4 to duplicate the factory jack. I have used them to lift the car with the two post hoist. Not as much stress as lifting one side of the car with a jack at one point. I usually extend the arms to lift on suspension mount points, a pain on such a low car.
I have a couple of lengths of 5 x 3-1/2 angle and 2 x 10 planks I am going to use to make bridges between the arms so I can just drive onto the hoist. Trying to work out how to make them portable and easily removeable, but safe.

[vvise]

The jack point looks solid, very nice. I have never used the jack points on the sill - my car would have crumpled.
I looked at my original jack - it appears that it is made to fit with the seam of the sill down the middle, likely so that it won't slip.
Here's my jack:
jack pts.jpg
and the instructions from the manual in the glove box:
jack.jpg
Your setup looks much more solid.

very interesting. didn't know these were the official jack points. thanks for the info.

I only every use the front crossmember, the seatbelt pockets, and the diff.



Noll that reinforced side point looks great, will make things so much easier in the future (assuming you don't slide off it).

[Noll]

Thanks all! Zedfoot, that's a smart idea, good way to spread out the load.


vvise, thanks! It should be alright, I thought about welding a bead on the outside edge to make a lip for the jack to hit before sliding off, but I don't think the plate is wide enough to both do that and have the jack cup sit flat. It shouldn't be too much of in issue, but I might spray some bedliner on there to add some texture for an extra level of safety.


---------------------------------------------------------

Muffler I ordered a while back showed up today. It's not exactly going to be the quietest thing in the world lol, but it and the resonator I also have should cut out the drone which is all I really mind. I'll be welding some 3" stainless tube to the back as a muffler tip so it extends far enough.




On to some actual work on the car. Mounted up the rear gas tank pipe shield (obviously not the final hardware I'll use):




I had ordered a bunch of hardware from McMaster Carr a little while back, and it came in today. Mostly boring stuff, but one of the things was some 5/8 bolts instead of the spindle pins:




Also got these, because there were a bunch of threaded holes for p-clips for brake lines that had bolts broken off in them and I didn't feel like cutting sections of subframe out just to weld new captive nuts in.




Drilled holes in the correct spots, welded them in, and cleaned them up:





Next up, the handbrake captive nuts were toast, so I made some new ones and welded them on:








Lastly, I welded some captive nuts into the rear trunk floor so if/when I eventually go to a small rear-mounted battery I can make a bracket easily without having to drill any holes in the car:



Not too much left now before paint can happen.

[grannyknot]

Noll, don't know if you follow Hybridz but here is a recent thread on using the 5/8" bolt, pro and cons. https://forums.hybridz.org/topic/132...omment-1226490

[Noll]

Noll, don't know if you follow Hybridz but here is a recent thread on using the 5/8" bolt, pro and cons. https://forums.hybridz.org/topic/132...omment-1226490

Oh yeah, that was one of the threads I found when I was searching on the topic and trying to decide if to do it or not. Gnosez's post about having used the bolts for 16 years/250 track days was what gave me reassurance to go ahead and decide to do it.

I dunno if I'll end up grinding a flat for the crosspins, I was talking with him (John Jeffery) on FB messenger recently and he said that he finds that there is absolutely no need for it, even if wear happened (and it hasn't to his in the last 16 years) it should happen to the bolt first before the strut housing.

He's a cool guy, just sent me some headlight bucket assemblies (the bits that bolt to the sugar scoops to hold the lenses in) for a good price and has provided some good advice on some bits of my Z.


----------------------------

I'm on to the boring-but-necessary stuff before paint; today I finished stitch-welding the d/s inner arch, welding the bottoms of the camber plates, and getting rid of all the remaining undercoating. That really sucked, but at least it's done now.






The (hopefully) final list of things to do before painting the underside of the car:

- get some snapped off nuts out of a couple of the brake/fuel line mounts, and remake one of the mounts entirely
- finish up the repair on the d/s (lower) dogleg and build the inner arch out to match
- make a couple of those bendy wire holders and weld them into the trans tunnel to replace some rusted-off ones.
- finish the last front tube bracing
- general weld cleanup inside and out
- degrease/acetone to remove all the undercoating residue, then scuff everything for paint.

[Noll]

Decided to head out to the garage for a bit to plug away at the list of jobs a little more.

Drilled out/retapped a couple of the brake/fuel line brackets that had bolts snapped off in them, and then re-made the rearmost one entirely because it was rusted to nothing:








I then made up some new wire ties for where they had rusted off here: