Starting a new project...Subaru STI Differential swap into my Z

[Zedyone_kenobi]

My seals and my rear diff cover came in today.

Just waiting on some hardware and we can start zipping this puppy up.

ON quick question, do you have to trim the bump stop on the RT mount any? I recall some folks having to shorten it a bit. It would be good to know BEFORE I bolt it in and have the diff suspended over my head.

[Captain_Zeros]

Yup, 3/4" for an r180, which is three 1/4" steps on the bump stop that was supplied with my mount from TechnoVersions. Pretty easy to do with the bump stop in a vice with a hacksaw.

Disclaimer, I forget the nominal height of the bumpstop if you have a different one than I did, I'm pretty sure it's available in at least one thread in this forums.

Here's a rusty crusty picture I got of it installed by jamming my phone up into the tunnel when I did mine and a picture of my uncut bump stop before the install (check out the shiny spot on the diff! That's where it was clunking from broken mounts!)

[Zedyone_kenobi]

That pic is spot on bud, thanks!

I will check out the other RT mount threads to get an average, but your picture is what I remember!

[Zedyone_kenobi]

Oh Oh, I am starting to think I leaped before I looked...

Looking at this image from wolf creek racing, it would appear that the bar that joins the lower support for the rear A-arms may interfere with my shwanky new diff cover..

in the words of yo semitie sam.

RAzzle Frazzle fragget

[madkaw]

The diff is the same exact dimensions as the one you took out- you don't need that curved bar.

[Zedyone_kenobi]

You are saying I do not NEED that curved bar. I would think it would provide some sort of useful stiffening. Or else why would Datsun engineers put it there. I know the diff is identical, but my new Perrin Cover sticks out further than my OEM cover did. It may hit the curved bar in question...

This may require some investigation..

I If you get rid of that curved bar, then what holds the bearings?

without that bar, the curved sections would be missing. I need to get back under the car again to see what is going on.

Edited November 19, 2013 by Zedyone_kenobi

[madkaw]

Oops - didn't see the previous post and pic Stephen - you might be screwed with that cover. I did the whole r200 LSD thing with the big finned cover and had to make a large Heim joint to connect the LCA's.

so either dump the cooler cover and put a stock one on or you have some fabbing to do

[Zedyone_kenobi]

Well there is always this option

Edited November 20, 2013 by Zedyone_kenobi

[Diseazd]

Zedy......The so called curved bar was so that the diff could be moved back in the later Z's to move the half shafts back so they didn't come out at an angle. Your Z is obviously an early 71 with the straight bar and the short driveshaft. While you've got the diff out, you could get the curved bar, longer driveshaft and fix the early angular flaw. Simply install the curved hangar, longer driveshaft, late style diff mount and flip the mustache bar and you're updated. You can get the used parts at a Z wrecking yard. BTW .....installing the R/T mount in the early Z's (your Z) requires mods to the mount for clearance purposes.

Edited November 20, 2013 by Diseazd

[Zedyone_kenobi]

That is an interesting thought Guy. But I was under the impression I would need to get different half shafts as well?

I may just sell the Perrin Diff and use the stock diff cover and call it a day. Shame, loved the bling.

[Zedyone_kenobi]

MIxed bag today. I got the drive shafts into the Diff, they literally just snap in. Almost too easy, but I a sure they are right, and then I managed to wiggle that bad boy up in there and up against the RT mount, which if I am perfectly honest took a few blows of 'convincing' to get to line up. But I squeezed it in there. I am without a doubt sure that that diff WILL not move, ever. LIke never ever.

So then all went very quickly. Starting assembling things and everything is going VERY smoothly….

UNTIL

nobody mentioned that the driveshaft coupler on my driveshaft does not have at the same bolt pattern as the STI Diff. I took my impact and took off the huge nut holding the yoke on to the Datsun Diff and it came off with about 10 seconds of impact beating it down.

Then it hit me. What if the STI diff has a different number of splines. Tricky problem if my Datsun Yoke will not thread onto the splines of the STI diff.

EDIT:

Did some Net digging and apparently the input yoke (or companion flange) for the driveshaft is interchangeable between the Datsun and STI.

HUZZAH, I do not have to take it back out.

Edited November 22, 2013 by Zedyone_kenobi

[madkaw]

Yep,

I guess you just missed that fact about the flange. That's what makes the swap so sweet!

As far as the RT mount, everyone seems to have experienced the same thing as far as the tight squeeze. I had to beat mine into submission also!!

Now my car has the T-5 trans(borg Warner from the ZXT) and the flange will not change out from the r200 diff, so I had to have the Subby flange redrilled to match the DS(PITA)