Halfshaft length and R200 Swap

[Miles]

I have been researching this for hours and am not confident of my conclusions concerning the many opinions about needing the "shorter" 280Z driver's side halfshaft when doing the R200 swap.

 

240Z vs 280Z halfshaft length:

 

There has been much debate about halfshaft length and the R200 swap with the concern being that the R200 driver's side halfshaft is shorter to compensate for the R200 which bulges to the driver's side. The point being that if you use the 240Z driver's side halfshaft it will be too long and will bottom out causing binding of the suspension. Also, I have read of complaints about the 240Z driver's side halfshaft not fitting during installation.

 

I just measured a left and right 78 280z half shaft in the fully compressed position. They were both 12 1/2 inches center to center as measured at the fixed part of the yolk. I then measured the left and right halfshaft in the fully extended position and got 14 1/8 inches for the right side shaft and 13 7/16 inches for the left side shaft for a 11/16 inch difference. Is that enough to make a difference?

 

Question: Has anyone who did the R200 swap using their 240Z halfshafts actually experienced the driver's side halfshaft bottoming out or any installation or suspension problems?

[buZy]

Mine don't bottom out using 240z's. Though using MM arms added .200 for track width, but it was fine before that using oem..i think. It's very close. Check your travel.

Please someone correct me if I am wrong.

The shafts are shortest at full droop.

I think all the shafts are the same, and same length. all 240 280.

[mark]

I know the ZX CV halfshafts are different lengths but did not know the u joint type were also different lengths. Can anyone confirm this?

[jt1]

There has been a lot of discussion of this, and a lot of conflicting info. Of the U joint halfshafts, all the one's I've measured were the same length, if measured center of u joint to center of u joint.

 

The splined diff flanges that snap into the diff are different, and this may be where part of the confusion lies. If you measure overall length of the halfshaft/ diff flange/companion flange assembly, they are different.

 

And, isn't the R200 offset in the chassis?

 

John

[JMortensen]

I too measured a bunch of shafts and they were all the same length. So did John Coffey. Compressed length is what's important, and if you got the same compressed length, the extended length would also be the same. One of the shafts may have had some grease at the end that made it hard to extend, or a stiff boot or something and that may account for the measuring difference, but as far as I've been able to tell all the halfshafts are the SAME length, whether they are from a 510, 240, 260, 280 or 280ZX (and probably some other Nissans from the 70s and 80s)

 

I do not believe that they are shortest when at full droop. That's where you can barely get them installed, but that doesn't mean that's where they're shortest. The real test would be for someone to take the time to remove the spring and install the halfshaft and run the suspension through it's travel and test for bind. Barring an actual test, we're all just speculating.

 

Shortening a halfshaft is not a big deal. I figured out what needed doing and then found that Tom (2126) had also done basically the same thing that I was planning on to fix the issue. Here is an old thread that deals with the subject: http://forums.hybridz.org/showthread.php?t=104966

 

I also have pics of a disassembled shaft in my gallery so you can see what part needs trimming. Tom had it done on a lathe, my solution was going to be to cut the shaft on a bandsaw and tack weld the ball stop on the end. I think both would have worked equally well.

[johnc]

I did do a test on a 260Z. They don't necissarily bind, they just bottom. This causes other parts of the suspension mounting to flex and there's usually enough flex to not cause a bind. But what the bottoming does do is increase the wheel rate which gives handling problems. More here:

 

http://www.betamotorsports.com/benchracing/R200handling.html

[Tony D]

Bob Heckendorf just finished shortening his axle shaft 0.500" on a lathe after I linked him to some Bonneville guys who shortened their shafts much shorter for use in a Streamliner.

If you are really concerned about the compression binding, you can shorten the inner axle shaft on a lathe using carbide bits, but the interrupted cut, combined with lack of good old White Lead for lubrication makes for a busy day changing chipped cutter bits.

Bob's inner axle shafts look OEM now, just 1/2" shorter. This is for a 280Z that he is doing a V8 Conversion on, and which is lowered so the binding issue...even axle installation was difficult. Now it's like a normal height installation, and limit straps are in place for droop.

 

He mentioned that at this point of shortening, the spacer near the inner circlip needs to be recut and fit to the new length so the spacers and drive dowels don't go where they're not supposed to be during full droop. This may be a bit of paranoia on his part, but better safe that sorry.

 

I don't know if he took any photos during the process, I'll e-mail him and find out if anybody is interested.

[Miles]

The R200 front differential mounting bracket has the differential offset to the passenger side. Can someone compare side by side the R180 and R200 front mount and the mustache bars. Here are some pictures of the R200 bolted to the front mount bracket. Could it be that Datsun offset the R200 mounts to the passenger side to compensate for the wider R200?

[2126]

On my 1970 240Z, I've installed an R200 and half shafts from a 83 ZX. I concur about the lengths being the same on the half shafts. During my installation, without springs on the rear struts, I discovered that in fact there was a bit of binding on the left side when the half shaft was perpendicular to the diff. The passenger side was good to go. So, I shortened the half shaft for the drivers side by 0.500".....problem gone. The machine work to the half shaft is very simple. After disassembling the half shaft, (be sure not to loose any of the ball spacers), replicate the existing male splined end of the shaft, a 1/2" shorter. The only issue I ran into was finding a lathe that has a big enough thoat to allow the U-joint passing through it so the shaft can be chucked up!

 

Tom

[bjhines]

I have several examples of the 240Z, 280Z differential crossmembers.

 

The relative mounting positions of the bolts that hold the diff mount are the same. The 280Z crossmember is beefier than the 240Z unit. In adddition the 240Z crossmembers have 2 exhaust cut outs on the bottom sides. The 280Z units do not.

[Chris Duncan]

'75 280Z with '83 280ZX R200 diff.

 

I took the spring off and put the suspension through it's full range. The axle at the shortest point still has about a 1/4" of travel before bottoming.

 

I did rebuild this axle complete including the slide part of it with new grease and a boot.

 

This suspension also has full urethane bushings and a strut housing that's shortened 2" with the Rabbit/Scirocco Bilstein Sport struts with internal bump stops. And the strut tower tops are slotted for more negative camber and they were set full negative (1/4" movement at the slot). This should make the axle even shorter.

 

Somewhere in mid travel is where the axle is the shortest. at full droop and going toward full bump it is getting longer.

 

Under heavy road load it may be possible that this setup would bottom the axles, it would definitely be possible with rubber bushings.

 

This test did find another problem. The stock brake flex hose does not work with the 2" shorter strut. Not only does it hit the lower arm at full bump but it's also too short at full bump. Was able to fix this by re-locating the ends of the flex hose.

Edited July 13, 2014 by Chris Duncan