First off, I'd like to start out by thanking the staff at Matchless Performance in Carrollton, TX (Dallas) for providing the install photos and labor.

While there is information about this swap on the web, I wanted to provide a concise photo step-by-step install guide for the members.

After installing the Mazworx Drag Axles, and blowing both of the Mazworx modified factory 240sx 29-spline output shafts on the first pass, I found myself looking for upgraded output shaft options.

After talking to SMRacing on FA, he told me about the Q45 differential and the stoutness of this piece.

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 (R230).

All Infiniti Q45's came with VSLD differentials, making this a great upgrade for those looking to upgrade to R230 durability without having to modify the S13/S14 subframe.

The 90-96 Q45 had a 3.54 final gear, and the 97-01 had a 3.69.

The swap is VERY easy to do, and is a rather bolt-in affair using the S13 or S14 differential cover from your current differential.

Parts list needed:

A.) (Your Model S13 or S14) differential coverB.) Q45 VLSD differentialC.) Q45 or 300ZX TT Wheel Hubs (great upgrade for the 4-lug guys who have been looking for a reason to go 5-lug)D.) 300ZX TT Driver Side Axle (installed on driver side of 240SX) and Infiniti Q45 Driver Side Axle (installed on passenger side of 240SX).

Here are two comparison photos of the stock Non-VSLD 240SX Output Shaft (left), Q45 (middle) and Mazworx Modified 240SX Output Shaft (right).





OEM Q45 Output Shafts (driver and passenger)



1.) Start out by swapping the Q45 differential cover with your factory S13 or S14 diff cover.



Before we move to the next step, let's take a look at the size difference of the input flange on the Q45 vs 240sx differential. You will need to remove this piece from the Q45 differential, and prepare for modification.







2.) You will need to take a marker of same kind, and draw out the 240sx driveshaft yoke bolt pattern onto the Q45 input shaft, and prepare for drilling (4) holes.

You could also order a Q45 yoke and have it swapped onto the 240SX driveshaft. However, I dont see the need for the added expense, as the Q45 input shaft flange is large enough that I dont feel tapping four more holes will hurt the structural rigidity.







All done, now to install back onto the Q45 differential.



Richie painted this piece black for aesthetic purposes, but here is the drilled input flange installed onto the differential.



After this step is finished, simply bolt the differential into the 240sx subframe, and re-install.

Note: Your factory driveshaft will not need to be modified in any way.









I put together this spreadsheet that shows the effects of the Q45 gears on the RB25DET Transmission. It is simple to manipulate, as your choice of transmission may differ.

http://www.undergroundmotorsports.com/rb25q45.xls

Happy Driving!
Modified by underground at 9:50 AM 7/28/2007

Great info I plan on getting the 3.54 gear for my 240. How come it needs the 300zxtt driver side and q45 driver side put in the stated? why not just q45 rear axles or two driver side q45 axles?

please explain. Thanks

q45s are fairly abundant in our junkyards.

isnt the q45 driveshaft yolk simply just removing snap rings?

edit*: definitely a nice spreadsheet. its very helpful.

Bump!I bought the 90 Q45 LSD, and the driver's side axle. I just need the 300ZX TT drivers side axle, drill the input shaft, and the 5 lug hubs. I'll see if i can get everything started by tuesday.PD: Any info on, swaping the Q45 limited slip gear, into the 240sx differential to make it lsd, and keep my stock gear ratio?Has anyone atempted this before and if so does it works?Sorry for the threadjacking.

thread revival!

how is the diff holding up??

This will work fine. What you have to do is swap both the ring and pinion gear. Obviously the two have to be kept together. The 240sx should use the 12mm ring gear bolts and the Q45 uses 13mm bolt so your 12mm bolts will fit through the Q45 carrrier with slight play, but this is not a problem if they are torqued properly.

This is what I had to do on my Z31. Well, I had to swap the carrier into my z31 case because the Q45 case is short nose and the z31 case is long nose... The Q45 case wont bolt to a z31.

*ADDENDUM* Read if attempting swap into an s13 or s14

To install this rear end into an s13/14 chassis you MUST use the q45 carrier, you cannot swap the lsd into the s13/14 carrier due to the way the shims are stacked...if you do then the passenger side output shaft will extend out about 1/2" from the casing side and the drivers side shaft will not seat properly; DO NOT ATTEMPT I HAVE TESTED IN BOTH S13 and S14 rear ends.

For an s13 installation you will also need to buy spl's "J30 LSD install kit" because the q45 is a bushing mount differential where the s13 is solid mount.

Modifications to the q45 final are the same as the s14 when it comes to the differential input flange, strongly sudgest leaving flange attatched and using driveshaft as a guide as removing the input flange will require checking of rolling torque when done...not easy if you dont have the proper tools.Fit the s13 rear cover, use a hicas or r32 cover is possible for increased capacity as well as better cooling.Seal cover to final drive using nissan grey gasket or permatex grey gasket, clean and degrease all surfaces before sealing and be sure to allow gasket maker to dry for atleast 1hr before refilling, overnight is best.DO NOT LAUNCH OR BRAKE HARD FOR ATLEAST 24HRS IF GREY GASKET IS USED, YOU WILL CAUSE THE SEAL TO RIP.The driveshaft to differential washers must also be modified because of the location of the new mounting holes,one side must be flattened to allow for proper engagement...sudgest grinding down the locking part as that is the least susceptible to damage and is already split.Be sure to refill with good quality 75w90 gear oil with a gl-5 rating.

Torques of interest:Driveshaft to diff input flange 29-33ft/lbsRear cover 29-36ft/lbsDiff snout/cover to subframe 72-87ft/lbs (s14)Diff snout to subframe 72-87ft/lbs (s13)Diff cover to subframe 32-41ft/lbs (s13)Filler/drain plugs 29-43ft/lbs

SPL Parts http://www.splparts.com, check under silvia in the subframe section.

Modified lock washers:

Input flange modification:

S13 cover fitted:

Overall assembly:

Carl H wrote:*ADDENDUM* Read if attempting swap into an s13 or s14

To install this rear end into an s13/14 chassis you MUST use the q45 carrier, you cannot swap the lsd into the s13/14 carrier due to the way the shims are stacked...if you do then the passenger side output shaft will extend out about 1/2" from the casing side and the drivers side shaft will not seat properly; DO NOT ATTEMPT I HAVE TESTED IN BOTH S13 and S14 rear ends.

you can swap it. did it on my s13. using th q45 rear end with the 240x ring and pinion gear. yes the output side will extend, i had to take the pass output shaft and get it machined. been driving with it for almost a month now and no problem or leaks.

also you don't have to redrill the input shaft you can just swap it. they are the same spline.

again yes you can do those things but then you change the inherent design...plus machining can be costly if you live in an area where there are few machine shops.and again, yes you can swap the input flanges but did you check the rolling torque on the pinion after you swapped it? Im going to bet you didnt.what I posted was the 'correct' way to do it, but obviously with these cars sometimes things are getting rigged...i didnt want my outputshafts to go flying out under load or for a pinion to seize...I've already had to rebuild my r33 final drive and replace all the bearings and its not something i wish to do again.

r3v_v3ng3 wrote:
you can swap it. did it on my s13. using th q45 rear end with the 240x ring and pinion gear. yes the output side will extend, i had to take the pass output shaft and get it machined. been driving with it for almost a month now and no problem or leaks.

also you don't have to redrill the input shaft you can just swap it. they are the same spline.

honestly i don't know if it change the design but i figured they are both r200 so i used the 240sx ring and pinion gear and also the same washers. first time i put the bearing washer from the q45 and the output shaft fits but the pinion and ring gear was not meashing right. so i stared at it for awhile and then tried the bearing washer from the 240 and it worked. the only problem is that the pass output shaft which i got it machined. only reason why i put the 240 r&p gear is that i'm not making major power, i wanted to keep my abs and don't want to throw off my speedometer.

i agree with you because this really is costly, sourcing parts and machining, not to mention time consuming. luckily i got lucky and got a whole q45 rear subframe/end for $200. another 60 for the z32tt axle and $20 for machining (i shopped around and it was going to cost $100 for machining but luckily there was this one machine shop that only asked for $20). so thats about $300

what do you mean by rolling torque? i did torqued everything including the input to pinion. it was a bit@h to torque.

again, anybody trying to do this swap. just a heads up that its going to be costly and sourcing for the z32tt driver axle is hard. your probably better off buying an aftermarket diff

hey i just did this swap.. great writeup.. i got the 94 q45 rear.. just have one question..

i have a sr20det motor with a z32 trans. now when i put the q45 rear the driveshaft is 1" too short.. yeah it bolts up and drives fine but any1 think this will be an issue?

also any1 know where i can get a set of gears made for the q45 rear b/c top end is great but my bottom end is crappy

you can email me @ [email protected]

OS Giken makes short gears for the SR20 trans. They are pricey but it's one option.

Lev_96_240sx wrote:OS Giken makes short gears for the SR20 trans. They are pricey but it's one option.

dont have a SR tranny in it i have a Z32 one.. thanks thou..

Could you post pics of what you mean by the different way the diffs are mounted. It would be a great help

Where I can get this spl's "J30 LSD install kit"??? I need it for the 300zx non turbo Diff. IGoogle it and could not find it. my email is [email protected] thanks in advance.

Any one can help....???

SPL Parts http://www.splparts.com, check under silvia in the subframe section.

its on the suspension section then subframe

cool write-up, thanks for posting it up

Installing this rear now, one question which ebrake set up is best? Zn/a, Ztt, q45 or r33. I assume since your using the q rear and hubs that ebrake anchor bolt is used?

Sorry for bringing this back...but I'm in a bind.

I have a Q45 rear end, and also a NA 300zx rear end. I'm getting mixed opinions on what will be stronger, does anyone have actual experience with putting down serious power with the q45 rear end and axles and them holding up? Will the NA300zx rear end with axles and all be weaker? Someone is gunna trade me my na 300zx rear end complete for a TT rear end so that I can use the drivers side axle, but some guys who have more experience that I do are saying that I'm doing all this work and gunna end up blowing the rear out anyways. I'm going for a very high hp sr20 here mated to a z33 tranny. Also, they suggest the 4.08 gear in the na300zx will be much better for me than the 3.55 in the q45, since my 350z tranny uses a 3.4 final drive.

I really need some experienced help here on this, thanks a lot!

I know the splines inside the diff to the output shaft have been counted but on the outer axle I counted 32 splines. I just wanted to verify that this is right. Can anyone comment?

you talking about the actual cv shaft that goes in the hub?

Yes. I thought 32 was a weird number for it and wanted to make sure I bought the right axles. I'll post a pic of them if need be

super thread revival but, i swapped the q45 diff in my s13 and after driving on it for 30 miles today i felt a clunking driving, on the driver side the axel where it bolts to the diff half shaft all 6 bolts came out, the cap popped off and the grease went everywhere.... why the hell did this happen? also note i havent even driven the car over 70mph yet...

I may be a few years late to the party but I have some quick questions as I'm in the middle of a research phase for a new project car. I plan on doing a LS376/525 + 4L70E swap onto a Gen 1 240sx platform. The Q45 has peaked my interest because of its bolt in nature and the fact that it's a more OEM solution.

I've already talked with someone at Driveshaft Shop about custom axles so I can retain the 4 lugs and have some Bullitt-proof axles to mate up. My two questions are; should I retain the factory Q45 output shafts and if I manage to find a car with ABS, would I be able to retain ABS with the Q45 diff?

I don't want to get into all the specifics of this build, as it is still in the planning phase (i.e. notebooks and binders full of notes, printouts and spreadsheets).

i may be a few months late for ya, but here's what i've found out:

abs wont work. i thought about possibly getting the abs module out of the donor car, but thats as far as i got with it. when i put the j30 diff in my s14, after about 30 mph, the abs light came on(looks at pinion shaft speed [gear ratio changes mess with calibration] for the rear wheels and each individual front wheel.

I wouldn't change out output shafts. i used an early q diff with late q output shafts and there was always a leak. maybe the seal was bad, but it looked fine. i didnt like the feel of the other shafts sitting in the different diff anyway. to continue:

z32 N/A diff(4.08)(pinion speed abs sensor-WILL KEEP ABS CALIBRATED)- grab early j30 axles

late j30 diff(3.9ish)(pinion speed abs sensor)-straight bolt it.
early j30 diff(pinion speed abs sensor)-grab the early j30 axles (5bolt) also . stronger joints and larger shafts.

97-01 q45 diff(3.69?)(axle speed abs sensors-def WONT work with s13/14 abs)-grab j30 axles (5 bolt).
pre 97 q45 diff(3.56?)(pinion speed abs sensor)-driver q45 axle/driver turbo z32 axle(impossible to find for less than $350)/q45 hubs****HOWEVER****350z axles measure to a length that should work, have the correct size 6 bolt flange for the diff AND 29 spline hub so you can keep your stock s-chassis hub. they just arent as thick as the Q/TT axles on the CV Joint splines. i'm looking for some armada shafts to see if they are any thicker and will bolt up.

so far swapping CV joints on different axles hasn't worked out yet due to axle diameter being different at the splines for the joints.

This may be a bit off topic since I'm sure most of you guys aren't after 3.13 gears... but is the statement at the very top of this thread that "All Infiniti Q45's came with VSLD differentials" true of the 2002-2006 Q45's that came with 3.13 gears? I have a Skyline R200 with 3.54 gears currently in a custom car I built -- but need a taller gear and LSD. Appreciate any info you can provide.