Q45 differential info. UPDATED!!!!

[rusolena]

As you all know, Q45 differentials from 1990 to 2001 all fit the s13 and s14 platforms. For the s13 you will have to change the cover for your own, but for the s14 you can keep the Q45 one. The 90-96 Q45 (R200) features the same beefy 6-bolt 30-spline axles, hubs, and output shafts used in the 90-96 Nissan 300ZX TT which is a R230. Ours is a R200. The 90-96 Q45 had a 3.54 final gear, and the 97-01 had a 3.69. I picked up my Q45 differential about a year ago and never had a chance to put it in my car. Now I have a subframe and the differential that have been sand blasted and power coated. As I started researching the swap, I came across a post on a forum where they showed the whole affair in a s13 car. They mentioned how the mounting points is the same on the subframe, how the shafts must be used (one from a Z32 driver side and the other from the Q45 driver side to be used on the passenger side) hubs and so on. The differential that was used on that particular install is out of an infinity Q45 97-01 model. It has an ABS sensor on the case by the front mounting points of it. The article or post showed pictures where you can clearly see the round teethed pinion on the input flange next to the normal 240sx s14 one. I had gone as far as having a custom driveshaft made to accomodate for the difference on input flanges from one to the other. Well, this is the interesting part. As I started talking to my friend Eddie, we realized we had 3 different differentials laying down on the garage. One from a J30, another from a Q45, and the last one from a 240sx s14 one. We took the input flanges out of each differential and found out that:

1. 90-96 Q45 differentials can use s14 differential input flanges.
2. 97-01 Q45 differentials can use J30 differential input flanges because they have the same ABS sensor on the differential case and input flange.

The good part about all of these differences is that no one has to make a custom driveshaft to compensate for the difference in flanges. You will be able to use the same driveshaft you have in your car. The only reason you may have to do a change of yokes may be that the Q45 one is larger in diameter and stronger at the same time. Other than that, everything else is golden. I have some pictures but I do not know how to post them. If someone wants to host them, I will gladly email those to you so they can be seen.
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[eazye2000]

That's pretty good info. Simple to understand, which is great for me.

There is a virgin '92 Q45 at the local junk yard. I think I can have front and rear suspension for 200 bucks out the door. And I have an S14 diff in the shed I can rob the stub shafts from. This looks to be a good idea for another project.

Is the '92 diff any stronger than the 240's? If it's not, then I don't want to mess with it. But it's a VLSD and 3.5something gears though, so it may be doable...

Either way, thanks for the info. I've not tried that hard to search, but since this is right in front of me it was a great read lol

[rusolena]

They have made over 800hp with these units ( Q45 differentials ). The axles are super strong, so I do not see you wanting a 240sx differential when you can use the Q45 one. Good luck with the install.

[broken40s]

when i did my q diff swap, i used the diff from a 95 q, swapped input flanges with my stock one, used output shafts out of a 98 q (5 bolt) with 93 j30 axles (5 bolt). had to visit 2 diff yards, but they were pretty close and they had all the parts for around 125 plus tax. also, i figured it easier to use the j30 axles since it'd be more expensive and harder to find the 300zx axle you need to use the q hubs, even if they arent as stong. but im not pushin 500whp either.

[Alonso]

Yea I swapped my stock pinion flange to the q45 diff so I could keep my stock s13 driveshaft. I did this back in '09...I even posted it on here.

Apparently nobody paid attention and missed it...

[supakat]

Yea a lot of people have done this. One question, why post in picture threads.

[rusolena]

Because I thought I remember how to post them as I was writing the post. It is simple as that. I forgot how to do it. That is why I suggested for someone to host them if it was needed. I could had emailed those pictures to anyone.

[rusolena]

Pictures have been posted. Unfortunately, I did not take the pictures of the differentials when they had their original input flanges on. I did afterwards. But anyways, you can see the 2 input flanges installed on the opposed differentials. Last picture is my subframe and differential. I hope this is visually helpful for everyone to see. Later

[96_240_KA]

So as long as I still use the 300ZX and Q45 driver side axles and hubs the 97+ diff will bolt right in?

[broken40s]

So as long as I still use the 300ZX and Q45 driver side axles and hubs the 97+ diff will bolt right in?

if you use the j30 5 bolt axles, that are easier to find usually, you dont even have to swap hubs with the 97+ q45 diff

[96_240_KA]

Awesome I really don't want to have to do anything twice if I can help it. Appreciate the insight.

[picsbypenny]

Do TT 300ZX hubs bolt in to s14?

[aaronlee97]

Do TT 300ZX hubs bolt in to s14?

I believe that they do. Are you using 300zx rear brakes?

[picsbypenny]

no, I have Q45 diff, Q45 & TT Driver Rear Axles... Everything else is stock.

[aaronlee97]

You must have the Q45 rear hubs as well and the special irregular bolts that come with them OR you can simply cut the Q45 hubs and make them match the ones from the 240. Look at my current build thread below to see what I'm talking about. I outlined the stuff needed and pointed to some websites with more info.

[Alonso]

Rear Q45 hubs=rear 300ZX TT hubs.

[mewantkouki]

Are the ring and pinion gears interchangeable with s13 / s14 stuff or does that defeat the purpose? 3.whatever final drive kinda sucks... unless you're doing 200mph runs.

[aaronlee97]

That depends on what your goals are. If you are looking for a nice DD with some added load to help spool a bigger turbo you're on the right track.

Not sure about the other stuff.

[Batman29]

Hi
I'm in the process to install a Q45 differential to my S14 and I would appreciate if you can send me the pictures that you mention in your post
Thanks

[R34SR]

I did mine over 10 years ago I barely remember the details.

Fairly sure I have a 93 j30 vlsd 3.93 ratio and running 6 bolt j30 axles.. I did a 5 lug conversion at the same time and I think i did a Non abs s14 one piece drive shaft to make it all work.... 10 yrs+ works great.

[p00t]

Mine is from forever ago and I did wacky ****... 93 q45 case, 3.54 ring and pinion /w s15 helical diff into my s13.

The case will mount into an s14 fine. For s13 you need spacers to replace the front bushings (SPL makes/made them?) and swap the rear cover.

For the input shaft -> if your car is ABS replace the end u joint to the bigger one at a driveshaft shop or test fit your driveshaft onto the input and mark the holes and drill the new smaller pattern. The centering ring on the input flange is the same size so you don't have to worry about it being out of balance/off center. If your car is non-abs you will need to get it shortened at a shop or buy an abs driveshaft.

For output shafts you may get lucky with an VLSD s14, compare the pattern/sizes on the splined part of the output shafts. You can convert the axles as explained above with the J30's.