z31.com

[SATAN]

Some of you know I am doing this, some of you dont.

The Q45 input shafts are 1mm larger and 1 extra spline, just a little more beefy than the 29 spline 30mm z31 input shafts. I am going to be running the Q45 carrier in my z31. Just so you know, the Q45 shafs and the twin turbo z32 shafs are the same shafts. They are 100% interchangeable. However you cannot put the TT carrier into your R200 case. Why? Because it is the R230 with the 230mm ring gear instead of the 200mm ring gear. Just wont work, sorry.

If this is something you want to do, Or dont know if you should be thinking about doing these are some things you should know.
1. you need the 90-96 Q45 differential, input shafts and half shafts. This is the only year that came with the VLSD and the 31mm input shafts.
2. You are going to have to have custom axles made. Not the CV's and everything. just the axle part between the two CV's. On the Q side it is slightly larger than the Z side. Yes you have to take all the half shafts apart and build them back up with the new axle's.
3.The z31 ring gear bolts are 12mm. The Q45's are 13mm. Now the 12mm bolts fit through the Q45 carrier just fine but it leaves slack. If you torque it down to the proper specs it will be fine. If you are putting a shit load of power through it, it would be wise to make a spacer to eliminate the slack. This means you have to find a .5mm wall spacer though. Good luck.
4. You are still stuck with the shitty VLSD. So the instructions below are how you make it solid for your race car if you dont feel like sourcing the R33 6 bolt 30 spline 2 way diff.
5. This swap will do you absolutely no good, if you have not upgraded your axle stubs as your stubs will break long before the diff side of things. I am running the Modern Motorsport stub/companion flange set.
6. This differential is proven to be good for 1.3 60' times in 3000lb cars.
7. Supposedly these splines are actually larger than the Ford 9". I have never measured a Ford 9" But I have these measurements if you would like to compare. So you can keep your IRS and still have it be just as strong as a 9".

You have to drill into the viscous coupling. You have to span the splined section and the spider gear section. I had to buy special tungsten carbide drill bits. Cost about $30 for 5 of them. Not TO bad. Do not try this with a regular drill bit. Why? Well, just look at the failed attempt below. But anyways...I drilled out half of the splined section and half of the spider gear section with a 3/16" diameter hole 9/16" deep. Then I slid a hardened steel pin in the hole and tack welded it in place. This makes it solid. If you install it like this, you will have an open diff. Now is where you need to weld the spider gears in order to have the solid diff. Dont even bother welding it if you dont have the spider gears clean, or you have a shitty welder. It is a waste of time if you do because chances are good it will just break the welds that never grabbed in the first place.

To drill one hole takes about 7 to 10 minutes. You have to go very slow at a low RPM due to the fact that tungsten carbide is very brittle. Very hard, but very brittle.

Here are the pics. They look like they are welded a lot, but keep in mind, it is only a 3/16" pin, and it is only welded on the surface. I didn't weld a lot because I didn't want to mess up the heat treatment in the hardened steel. The tack weld is just to hold the pin in place. One of the holes I drilled slightly to far, and viscous fluid started leaking out. Not like it matters, I dont need it anyways. You can also see the failed attempt on the right, when I tried to use a regular drill bit. Yeah that was dumb.



_________________
Fabricator, doing what I do.

[SATAN]

Here is the spider gear assembly with the solid viscous coupling all welded together. If this breaks, there is no hope for life as we know it.

Piece of steel inserted to give the pinion gears more to grab on to.


And the whole assembly welded all to hell. Not pretty, but I was going for penetration and strength and didn't care about what the welds looked like. And before you ask, yes everything still fits in the carrier just fine.


_________________
Fabricator, doing what I do.