My 240SX rear IRS swap into my 240Z

[maichor]

I had questions again about my swap so I will post a writeup I started a while back. I will be adding to it. Let me know what you want to know and I can add it.

 

Enjoy!

 

Putting and independent rear suspension from a Nissan 240SX into and early Datsun Z car

 

Tools Used:

TAPE MEASURE, TAPE MEASURE, TAPE MEASURE!

Hammer

Pry bar,

Metric wrenches

Angle grinder

Sawzall

Drill

MIG Welder

 

Parts:

R200 from a Q45

Moser custom axles

Complete IRS from a 240SX,

upper arms are from a Q45 because they are stronger and solid cast

240SX hubs were replaced by Q45 hubs

240SX brakes were replaced by 90-96 300ZXTT brakes

Rear Wheels are 17 X 10.5 Cobra R wheels 6.95†back space

Michelin XGT 335/35/17’s from a Viper

 

What is involved:

Cutting out a significant part of the rear subframe of the Z and reinforcing the area for the 240SX mounting points.

Welding in plates for the mounting points.

Centering and drilling holes for mounting bolts (I used the original mustache bar mounting holes and bolted a plate to that with the 240SX mounting points centered to that and with the proper alignment front to back.) I also moved the suspension back about .75†to center the tires in the wheel well. Stock Z has the tire forward a bit.

 

CAUTIONS:

Not for the faint of heart. This requires several trial fits with cutting in between.

I did this on a 1972 240Z with a Velo Rossa kit ~10†wider than a stock Z.

I am using an F-body fuel tank to go with my LS1. Make sure the suspension will clear your tank, it should.

You may lose the stock seatbelt locations. I always planned on harnesses, so I did not try to save them.

 

Things to remember:

The 240SX subframe puts the differential on center. The 240Z has the motor off to the passenger’s side by about ¾â€

I mounted my subframe all the way up under the body, (i.e. as high as it will go in the rear.) What is important is to mount it in line with the transmission so your driveline angles will be as near as possible.

 

 

 

How the concept developed:

 

I started my project looking for a way to accomplish a few things. The Velo Rossa body kit for the early Z car has about 5†of extra width per side over stock. So, I wanted to fill the wheel wells with tire. That meant wheels. Try to find a 17†or larger wheel that is also 10.5 to 11†wide. That proved impossible on my budget. Instead of custom wheels, I looked at 5 lug options. At the same time I was looking to beef up the rear end and had come across the R230 conversion that some had done at http://www.hybridz.org. It turns out that I was really looking at an R200VLSD and not the R230. I later Bought a 300ZXTT diff (R230 with 3.7 gears and swapped it in.) Back to the story… I went to the junkyards looking for R200 differentials out of 90’s Infiniti Q45’s. I found three in the first yard I tried. I spent an hour and a half piecing together the rear suspension from a Q45 and a J30. All the pieces looked interchangeable. I found a 240SX (S14) with the same setup. I was very impressed at the engineering of the setup. I also stacked the subframes for each of the cars next to each other and found that the Q45 was an inch wider than the J30 and that was about and inch wider than the 240SX. I tested the Q45 R200 in the subframe for the 240SX. It fit. I went home and started thinking about the swap. I would have 5 lugs 5 on 4.5â€. I would also have a working Ebrake, larger vented disc rotors, and a very well designed multi-link setup.

 

I knew someone with a J30, so the next day, when I saw her, I pulled out my tape and measured outer edge of the tires. It came out to be ~69†(Velo Rossa rear tub is 70†wide.) I also checked to see if wider wheels would clear the rest of the suspension on the inboard side. I guessed I could get another inch on each side there with the right backspacing on the wheels.

 

I went back to the yard determined to figure it out. I took measurements of the 240SX mounting points to see if it would fit under the Z and where it would have to be mounted. I also wanted to take the best parts from the cars to make the suspension. The axles for the Q45 were 1mm larger from what I could tell trying to fit them in the J30 hubs. The 240SX axles were 1mm smaller. I looked at the mounting of the hubs and it looked like I could swap the Q45 hubs into the outer 240SX link assembly. I didn’t have my tools but I told the yard what I wanted. So, I bartered a price for the whole rear IRS but told the guy I wanted specific parts from each vehicle. Once we decided on a price, the guys in the yard helped me swap out the hubs. It was easy. I took the brakes from the J30 because they were vented rotors instead of solid. They bolted up as well. I later went with 90’-96’ 300ZXTT brakes which are a direct bolt on.

 

Have some photos at photos.yahoo.com/maichor75104

 

If you have other requests, let me know and I can post more.

[tannji]

Thanks for the reply and post.... I do have two immediate questions, before I go back to reading and pondering. Q45 lsd... compatible in your setup? and width of the 240SX subframe, vs stock 240. Am I looking at immediately having to go with some rear quarter widening, or with the right wheel and offset will it work as is? Oh, sorry, one more... how did you deal with anchoring the struts up top? stock strut towers, or?

 

Thanks man, you rock. (please keep that other thread up to date with frequent updates!!)

[maichor]

The Q45 VLSD is a direct bolt in for the 240SX subframe. If you wish to use and R230 from a 300ZXTT you will have to modify the subframe.

 

The width of the 240Z setup where the wheels mount is ~55". The 240SX is 60.5". Maximum backspacing on a 17" wheel is about 7". Total width to outside of wheels is about 67" for a 9" wheel. Mustang Cobra R wheels were used on my swap. I used a 10.5" wheel and that made total width about 69". If you went with an 8" wheel you probably could stick with stock fenders, but you will probably want flares.

 

I used the stock strut towers and stock 240SX struts with the 240Z upper isolator. Bolted right up with a slight increase in angle over 240SX. But, this is unimportant because the 240SX has upper and lower arms and so the change really doesn't affect anything. And, ride height was fine with this setup. You could use adjustable coilovers just as easily.

 

Note. Mounting points for the front of the 240SX are 42.5" apart. But, there are .75" holes farther up the front legs of the subframe. I cut of the front legs a bit. That left an opening in the end. I slid a .75" ID sleeve inside and put a bolt though. Then, I welded the sleve in place so that I could tighten the mount as much as I wanted without colapsing the front tube. The back mounts are 24.5" apart (narrower than mustach bar holes). It also mounts about 2.5" behind the mustache bar mounts. You must have the clearance to do it. It will be tight with a stock tank. You could get away with about 1.5" back instead of 2.5", but that will put the wheel to the front of the wheel well, like the stock setup.

[maichor]

I had another request for photos. It is hard to get a good pic of the suspension installed because the jackstands only allow close quarters for picture taking. Saturday I should have the car on a lift and I will shoot more then. Enjoy.

[tannji]

Wow, thanks for the pics and info..... that makes the job look a LOT less intimidating.... and the shot of the 240SX rear assembly out of the car is good, I like its design a lot.... including the front mount for the diff, looks to be much better than the native Z setup. thanks again dude!

[karay240]

Thank you VERY much for the pics . Sorry, I wasn't trying to jack the other thread. I was getting desperate for some type of pictorial guidance.

 

I am going to try to talk to some of the tuners in Japan next month that have done this type of swap. I'm thinking that they might've kept the subframe in tact, but they tend to be secretive about custom fabrication and tuning. I'll try to get some pics of those, too, but we'll see.

 

Again, thanks alot

 

Kenny

http://www.rbmotoring.com

[Hugh]

Yeah, no kidding. At the drag strip or the street races, if I were checking out a Japanese guy's car... I'd have to play dumb to get specific information out of them. If they saw what I was driving, they'd avoid telling me anything.

 

Heh heh... I guess they were afraid of the gaijin competition.

[Guest zline]

can you post a larger version of this picture?

 

[maichor]

Here it is. You are looking at the rear portion of the passenger's floor. I cut the floor our and boxed it to allow me to move the seat farther back. The plate clamped into place is 3/16" steel. One was welded there and one to the front of the tool cubby. I then notched them out and put at 2 X 3 X 1/8" from the upper unibody through both plates and to the subframe connector and welded everything in. This is way overdone, but I have no roof and I wanted to make sure the car would not sag or flex too much.

 

[Guest zline]

sweet thanks

 

 

I do not plan on cutting the floorpan out. Just removing the S30 rear suspension putting the S13 in place of it and then gusseting the shock mounts like this

 

 

Keeping the stock S13 mounting points, I have a full set of adjustable RUCA, toe link, traction link so any setting can be adjusted with flares wheels should only stick out a BIT with proper camber it will be super flush.

 

Once you cut the rear frame leg off, did you install a sleeve on the inside and weld it shut and then link the two rails together?

[maichor]

Yes, except the sleeve. Although . . . that would be a good idea for you. When I added the second frame rail to move it inboard, I closed the main one without a sleeve, then welded them together, then they were both welded to the floorpan and the 1/8" extended floorpan that I made. It is not going anywhere. Remember, I also have 3/16" plate on the arm coming down from the old unibody through and welded to both those plates and then to the boxed frame. If you don't have the heavy extension I added, that area will become a flex point. Sounds like you have a cool project!

 

Keeping the front stock mounting points may work for you just fine. I wanted to really push the subframe up as far as possible to get a low stance. That meant I had to lose about 6" of the length of the front arms.

[karay240]

what's up maichor, just had one more question. You said that you used the OEM 240SX rear suspension. Did you use the S13 or 14? I'm beginning to buy parts for this project, and I don't want to get the wrong ones.

 

I'm actually planning on using both the front AND rear coilovers for the 240SX. I'll have to get different spring rates that the average 240SX owner (I'm going SR in my Z), but we'll see how it goes.

 

Kenny

http://www.rbmotoring.com

[maichor]

S14, however, all of the arms are swappable except the lower control arms. For example, if you wanted to run the aluminum hub housing from a 300ZX (Z32), you could, but you would also have to have the lower control arms from the Z because the ball joints on the LCA are different. Also, I believe the S13 hub assembly is different than the S14 so you would have to use S13 axles with the hubs (Smaller than Q45 and 300ZX). With the S14 there are four bolts holding the hub on and one giant nut holding the whole assembly together. Maybe when I get home I can post a pic of the hub assembly. I would go S14, just so you have more options later. S13 will work fine, but you will have to stick with S13 axles, even if you want to upgrade later unless of course you buy the S14 hub, housing and LCA.

[karay240]

I'm still toying w/ different options on the multilink. We have several S13 ones @ the shop, so I'm probably going to "practice" on one of those. Once I fugure out all there is to, I'm either going w/ R32, 33, or S15 (whichever becomes available at the time)

 

I'm going a little different route than you, though, inthat I'm probably just going to weld it in. It won't be as civilized as the insolated ones, but the subframes I'm thinking about have bughings that isolate the diff (the S13 is rigid mounted), and I'm not going to be getting pillowball arms (okay, maybe the upper control arm and toe control arm. . . but that's it. lol.)

[Guest zline]

yes, if you DO NOT have a roof i could see that becoming a flexpoint

 

but a 7 point welded in cage & sleeved frame rails should eliminate any flex created by cutting off that lower frame leg. with coilover in the rear, should be able to get any stance i want w/o any problem.

[Guest gema]

Hey gentlemen,

 

Is it realistic to presume one could not simply swap the IRS, but the bulk of a 240sx suspension into the 240z? I'd like to 'update' the car, and this would open a LOT of opportunities for performance parts, and in addition, permit the use of those fancy Tein EDFC coilovers. I have a MIG welder, an air compressor and assorted tools, limitless determination and the almighty "Search" feature. Thanks for reading.

 

maichor, awesome pictures =)

[Sven]

Maichor, any idea on your weight increase with the S-car setup? It makes for a surprisingly straight forward install. Good work. It opens up a world of options- part wise.

[Guest JAMIE T]

Ok, so I know this is an older thread, but I'm just starting to look into rear end options.

 

I have an R230 and a pair of axles from a ZXTT. I was going to just use the available parts to swap that in it but the issue of stub axle breakage still exists with that method. I want to bullet proof this car. Maichor, your write-up is fantastic and I applaud your efforts.

 

From what I've read here, The S13 rear parts don't allow me to "Bolt-in" the ZXTT hubs? But, the entire hub carrier from the ZXTT will bolt onto the arms of the S13? And, from your experience, would it be possible to narrow the rear suspension carrier to make the hubs (with brake hats) 55" apart to match the Datsun track? I am an experienced fabricator and ALL the equipment to do the work, but since I don't have the S13 parts to look at in front of me, I don't know if it is physically possible. I'd go with the S14 parts but they are harder to find around here. Also, what was involved in putting the ZXTT diff in the carrier? I already know I will need axle shafts made from Moser.

[maichor]

You will need the hub carrier from the 300ZXTT to work with the S13 Subframe "carrier" and your axles will need to be shortened. I narrowed up the subframe 1", you could probably go 4" shorter max, but you would have to take it out of both sides and it would not be as pretty because you would have to cut some of the supporting metal. That would leave your track 1.5" wider than stock in the rear, or .75" per side. PM me if you want a better description and we can talk on the phone.

 

I recommend getting new custom axles from Moser at your desired length. Shortening and reslpining the hardened steel is a machinists nightmare. After several quotes, I gave up and got new axles. Also, to save a little money, you can use the cast iron hub assembly from the 90-96 Q45. There is virtually no demand for these and I picked mine up cheap. You have the option of keeping the Q45 brakes or using the 300ZXTT brakes. IF you are upgrading the brakes, I would find 300ZXTT hubs with brakes and buy it all, remember to get the 300ZXTT lower control arms.

 

Good luck.

[Guest NavySupra]

Is there much difference between the s13/14 rear end setup and that of a late model(88) z31? I have a complete z31 core at my shop, like the whole car and everything is in excellent shape but i don't have papers for it, so i'm thinking about cutting it up for parts for my s30.