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

[Zedyone_kenobi]

I think Blue is having a side bar not exactly on this subject. But related

The OEM Datsun half shafts should bolt up to the Wolf Creek output flanges just fine. I have not checked the fit, but I am not too worried about it. They should fit, if not I will deal with it. This is all about rolling with the punches and not making a square peg fit into a round hole. The right decision will not always be the easy or cheap one. But I will tackle my half shafts after I get my Diff done up the way I like it.

I have just been cleaning up parts with a wire wheel and gathering some hardware…

[240260280z]

Yup... I like what you are doing but $500 for the stubbies from Wolf Creek is the hardest part of the upgrade in my opinion. There may be a less expensive solution. The Yoke solution arose from your trouble getting those short faced D cut bolts. A Yoke with 27 splined shaft would be a nice keystone. That chev or a similar yoke may be all that is needed with some machining...if lucky.... keep going....sidebar or not

[conedodger]

This a corollary to the subject but it has been brought up several times. An LSD and a TBD aren't the same thing. I assume that since I hear the STi uses a Torsen type that it is actually a TBD you are putting in. Having used Quaiffe and Gleason/Torsen TBD's for years, I can speak to the difference they make. Those of us who race and autocross love our 'mid-corner speed.' When you go back on throttle in the corner, the only drama is acceleration not wheel spin with the TBD.

It is often said that LSD is best for road race courses, so to us grassroots guys who don't race, that means DE, it is also said that TBD is best for autocross.

My Z uses a real honest to goodness Datsun Competition Limited Slip Unit, in fact the suspension and exhaust on my car looks like a old Datsun Competition poster child. I like my 914's TBD much better.

You will like it too Steve.

[Zedyone_kenobi]

need some advice on what kind of mount to use with the new diff

Here are my options:

1) Buy a new strap and go back to OEM. Motorsport sells replacement straps that will probably work.

2) Go with the RT mount with the bump stop on top and the OEM on bottom

3) Go with the RT mount with the GM motor mount option that has no lower mount (this one I need some help on)

Figure OEM would work, and I never really had a clunk to speak of. But I would be interested in opinions. Also if anybody knows the mount needed for the RT to work as a standalone let me know

THanks Blue!

I got the studs out of the other diff without any problems. I removed the flange from the OEM diff and then set it on a solid surface and with a 5 lb maul just tapped out the old studs. They pressed into the Wolf Creek flanges without any fuss what so ever. They went in actually very easy. Probably some permanent set on the studs, but they will work as they are.

Edited November 10, 2013 by Zedyone_kenobi

[madkaw]

This a corollary to the subject but it has been brought up several times. An LSD and a TBD aren't the same thing. I assume that since I hear the STi uses a Torsen type that it is actually a TBD you are putting in. Having used Quaiffe and Gleason/Torsen TBD's for years, I can speak to the difference they make. Those of us who race and autocross love our 'mid-corner speed.' When you go back on throttle in the corner, the only drama is acceleration not wheel spin with the TBD.

It is often said that LSD is best for road race courses, so to us grassroots guys who don't race, that means DE, it is also said that TBD is best for autocross.

My Z uses a real honest to goodness Datsun Competition Limited Slip Unit, in fact the suspension and exhaust on my car looks like a old Datsun Competition poster child. I like my 914's TBD much better.

You will like it too Steve.

I think it depends what year diff you get. I believe STI's used both clutch and TB

[madkaw]

#2 definetly

[Captain_Zeros]

Option 2 for sure. No reason not to especially if you've got the RT in hand already, it's way superior to the OEM design.

Rubber is strong in compression and weak in tension so with an RT mount and a stock mount sandwiching the diff then each mount gets to play to it's compressive strengths.

Using the RT as a standalone with a hanging mount isn't recommended for a stock engined Z as it changes the angle of the diff a bit to "less than ideal". It's really a modification for V8 swap guys as they need the slightly canted pinion angle to match up with the equally canted new engine in the swap.

Edited November 11, 2013 by Captain_Zeros

[Zedyone_kenobi]

Well then number 2 it is!!

[240260280z]

You may be able to adapt parts/philosophies of these designs to enhance.

https://www.classiczcars.com/forums/engine-drivetrain-s30/43448-two-clever-differential-front-mount-modifications.html#post374011

[Zedyone_kenobi]

Well I am well on the way to finishing this. I have all my seals coming in, and I am almost done tracking down some new shiney hardware. I polished the plates on the side with a wire brush and painted the new diff with some POR chassis black for presentation purposes.

I am still cleaning up parts in the spare time.

On a side note, has anybody priced the bolts that connect the half shaft to the hub on the rear wheel? EACH bolt is 12.57 at MSA! EACH BOLT!! You need 8 of them!!!! I am going to have to invest in a CAD plate kit from Eastwood soon. I like my hardware to be perfect when it goes together. I have a rare phobia against dirty threads... called impropertorqueaphobia

[beermanpete]

The bolts for the half-shaft to hub are available from Nissan at about $3 each.

[Zedyone_kenobi]

Oh I will reuse my old ones, they cleaned up nice, but I was just shocked at the price MSA wants, I would always call courtesy before ordering something like that.