My 240SX rear IRS swap into my 240Z
Posted 17 October 2004 - 02:46 PM
Putting and independent rear suspension from a Nissan 240SX into and early Datsun Z car
TAPE MEASURE, TAPE MEASURE, TAPE MEASURE!
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 6.95â€ back space
Michelin XGT 335/35/17â€™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 .75â€ to center the tires in the wheel well. Stock Z has the tire forward a bit.
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 ~10â€ 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 passengerâ€™s side by about Â¾â€
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 5â€ of extra width per side over stock. So, I wanted to fill the wheel wells with tire. That meant wheels. Try to find a 17â€ or larger wheel that is also 10.5 to 11â€ 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 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 storyâ€¦ I went to the junkyards looking for R200 differentials out of 90â€™s Infiniti Q45â€™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 ~69â€ (Velo Rossa rear tub is 70â€ 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 didnâ€™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 90â€™-96â€™ 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.
Posted 17 October 2004 - 04:14 PM
Thanks man, you rock. (please keep that other thread up to date with frequent updates!!)
Posted 17 October 2004 - 06:23 PM
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.
Posted 26 October 2004 - 06:36 PM
Posted 26 October 2004 - 06:51 PM
Posted 26 October 2004 - 09:17 PM
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
Posted 27 October 2004 - 05:49 AM
Heh heh... I guess they were afraid of the gaijin competition.
Posted 27 November 2004 - 10:33 AM
Posted 27 November 2004 - 11:02 AM
Posted 27 November 2004 - 01:03 PM
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?
Posted 29 November 2004 - 08:32 AM
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.
Posted 16 December 2004 - 01:29 PM
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.
Posted 16 December 2004 - 01:50 PM
Posted 16 December 2004 - 05:33 PM
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.)
Posted 19 December 2004 - 09:27 AM
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.
Posted 24 December 2004 - 01:56 PM
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 =)
Posted 25 December 2004 - 08:43 AM
'73 240z 3.1 Mikuni,Mikuni,Mikuni - the OD Green Z
'73 240z "The Driver", soon to steal engine from ^^^
'77 280z -spread across three states in pieces, SBF'ed eventually
'85 500SEC I refuse to drive nothing but the very best! (of 1985...)
'00 F250 7.3 PSD mostly in one piece
'91 Mustang Coupe - Dust collector, forgotten step child
Posted 09 February 2005 - 06:14 PM
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.
Posted 15 February 2005 - 08:42 AM
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.
Posted 25 July 2005 - 08:02 AM
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