Z31 CV Shafts

[Ezzie]

Are there different CV shafts used on the various years of the Z31?? I have two types here, one set with 6 bolts (3 clusters of 2 bolts) where they bolt up to the companion flange and one set with 4 larger bolts only. Are they interchangeable with the R200 clutch LSD from the 87+ turbo or will only one type work? I put the 4 bolt ones in but there seems to be a clearance issue where they snap into the diff (tears the seal apart).

[DaleMX]

I know Ross at Modern Motorsports shortens the shafts by turning one of the housings around to avoid binding problems. A search might turn up the procedure. He might have some details on his site. http://www.modern-motorsports.com/catalog/default.php

[Nigel]

The Z31 Turbo CV axles (4 bolt flange) should be the correct ones. However, maybe you have CV axles from the 1988 limited edition Shiro Z31 Turbo, or conversly, a Shiro LSD (Viscous LSD, not clutch type like the other turbos). The Shiro axles will only work with the Shiro LSD.

 

One other thing to keep in mind is that the stubs on the axles are different lengths, and wont fit properly if you try to put it in the wrong side of the diff.

 

Regardless, the normally aspirated Z31's with the 6 bolt flange are not what you want.

 

Nigel

'73 240ZT (with Z31 Turbo axles)

[Drax240z]

Will the Shiro axles work with the 240sx viscous LSD? That would open up some interesting possiblities.

[Ezzie]

The Z31 Turbo CV axles (4 bolt flange) should be the correct ones. However' date=' maybe you have CV axles from the 1988 limited edition Shiro Z31 Turbo.

 

Nigel

'73 240ZT (with Z31 Turbo axles)[/quote']

 

This is probably the issue. I got these axles (4 bolt turbo) from Bill in London and he may have gotten them mixed up. I know he did have a Shiro at one time (not sure if he still has it). When I snap them into my R200 LSD (clutch type not VLSD), both sides are up against the diff case. Are the stubs on the Shiro axles a little bit shorter than the non-Shiro ones?? Looks like they are about 6mm. too short (on both sides).

[Drax240z]

I thought the stubs (or at least one of them) were longer on the viscous setups, but I could be way off base with those thoughts.

[Z-TARD]

The VLSD should have one splined shaft that is almost an inch longer than a non VLSD setup, as well as one that is just a little shorter than the non VLSD. If both of yours are the same length, they most likely are not from a Shiro VLSD. Any pics to work with?

 

Mike

[Ezzie]

I'll take some pics and post them. For some reason my access does not allow me to post attachments on this forum. How would I get this changed??

[Ezzie]

I think I got this figured out. I dug out another set of spare 300ZX turbo shafts (from an '88 I think) that I have and compared them side by side as well as measured everthing. They are exactly the same as the ones I am using so I must NOT have Shiro shafts here. I think the problem is that there is nothing to prevent the stubs from going into the diff too far (as in past the circlip detents). I think when I installed them, either the pressure of getting things lined up with the companion flanges or not enough clearance may have pushed them too far in. Then the natural spring effect of the rubber boots just kept them there and they didn't pop back out far enough to snap into the circlips. Can see no other way this could have happened as the side gears in the clutch pack are identical on either side and all the spacers in the diff are in the right spot. I pulled my spare apart to check this to be sure and I had the diff together correctly.

 

I also found this on Ross's website:

 

"300ZXT 4 bolt outerflange CV shafts (not the 6 bolt type) require the end cap removed, and inner CV race reversed, this effectively shortens each CV shaft 3/8" and results in correct rear geometry for your Z. This modification can be done with typical tools and we can supply guiding pictures to help (easily done in 1/2 hour). They work with stock rear control arms, if you've shortened yours or any similar effect be sure to check for adequate travel without binding in compression."

 

 

Anybody else ever had this problem?

[zcarnut]

You did say that you were using the R200 LSD? Right?

 

Reason I ask is that Nissan used a “thrust block” on the later R200's to limit the distance that the CV axle flange can be inserted into the diff. It’s a piece that slides over the differential pinion gear’s axle shaft. The CV axles bottom out on this thrust block.

 

However, the LSD did not use this thrust block because it has four pinion gears and there is no room for it.

[Ezzie]

Yes, I am using the clutch pack type R200 LSD. There is no "thrust block" in the spider cluster, just a hole in the middle of the spider holder thingy.

[Nigel]

 

I also found this on Ross's website:

 

"300ZXT 4 bolt outerflange CV shafts (not the 6 bolt type) require the end cap removed' date=' and inner CV race reversed, this effectively shortens each CV shaft 3/8" and results in correct rear geometry for your Z. This modification can be done with typical tools and we can supply guiding pictures to help (easily done in 1/2 hour). They work with stock rear control arms, if you've shortened yours or any similar effect be sure to check for adequate travel without binding in compression."

 

 

Anybody else ever had this problem?[/quote']

 

Yes, you do have to flip the cage around on the outer joint (stub axle side, not differential side), or the shafts won't fit. I also ground down the end of the shaft until there was about a 1/8" of material left before the grove for the fist snap ring, just to give a little bit of extra clearance. I have some pictures at home. If I remember, I'll post them tonight...

 

Nigel

 

BTW EZZIE... Have we met? Do you know Manolo (He also lives in Georgetown)?

[Sean73]

Will the Shiro axles work with the 240sx viscous LSD? That would open up some interesting possiblities.

Yes, I have verified this. I bought a 240SX viscous carrier off Ebay, and my 88SS shafts plugged right into it. I posted this a while ago. They will also probably work with Z32 viscous carriers as well.

 

I am planning on using the 240SX carrier (in a 300ZX R200 housing), 88 SS shafts, and Z31 CV adapters from Modern Motorsports.

 

The Modern Motorsports Z31 CV conversion calls for you to reverse the inner cage on the wheel side of the CV shaft, this reduces the shaft length by 3/8". I took some measurments, and with these adapters, 88SS shafts, and an R200 installed in a 240Z, the shafts are going to be really tight -- probably tighter than R200 shafts which are already prone to binding in a 240z. Ross assured me they would work, but I'd like to see the measurements on paper.

[Drax240z]

Why are you choosing the 300zx R200 housing over the 280zx R200 housing? Am I missing something? (pulling a blank here though something tells me I know the answer)

 

Very cool and robust swap, should be cost efficient too!

[Nigel]

As promised (ok, I didn't really promise, but I'm doing it anyway), here are pictures of the outer CV joint bearing cage located in the stock orientation (ball bearings removed)...

 

 

and with the cage reversed...

 

 

It shortens the axle length just enough, especially if you grind down the end of the shaft a bit. And keep in mind, the axle is compressed the most when the suspension is at it's lowest. So when the car is on the ground the axle actually decompresses. Even so, there's no binding with the suspension at it's lowest, unlike a setup I've seen with the 280ZXT CV axles.

 

Nigel

'73 240ZT

[Drax240z]

And keep in mind' date=' the axle is compressed the most when the suspension is at it's lowest. So when the car is on the ground the axle actually decompresses. Even so, there's no binding with the suspension at it's lowest, unlike a setup I've seen with the 280ZXT CV axles.

 

Nigel

'73 240ZT[/quote']

 

Wouldn't the axle be at it's shortest when they are horizontal out of the diff? This will be different on different Z's depending how much lower it is than stock. IIRC the stock halfshafts go at a downward angle which would indicate to me that they would be at their shortest in bump.

[Nigel]

Wouldn't the axle be at it's shortest when they are horizontal out of the diff? This will be different on different Z's depending how much lower it is than stock. IIRC the stock halfshafts go at a downward angle which would indicate to me that they would be at their shortest in bump.

 

If you consider the geometry of the Z (not ZX) suspension carefully, it will become clear that the arc of the control arm actually pulls the hub in closer to the diff as it rotates down. Have you ever noticed that when you jack up a Z, the wheels drag inward as the car rises? Or, conversely, when you drop a Z back down to the ground, it looks like it has a lift kit installed untill you roll the car a few feet?

 

I can't quite picture what happens under full compression, but I'm pretty sure that the upward arc (above horizontal) of the control arm doesn't pull the hub in anywhere near as much as the downward arc, if at all. Regardless, I've never experienced any kind of binding.

 

Nigel

'73 240ZT

[Sean73]

Why are you choosing the 300zx R200 housing over the 280zx R200 housing? Am I missing something? (pulling a blank here though something tells me I know the answer)

 

Very cool and robust swap' date=' should be cost efficient too![/quote']

 

Drax -

The housing doesn't matter, but it helps to use a 86-89 R200 because the ring gear has 12mm holes to mate with the 240SX LSD.

 

Nigel - did you measure the axles before you installed them? I can't figure out how the Modern Motorsports adapters are going to work without binding. For example, on my 240Z with R200, the driver's side halfshaft (wheel side outer flange to diff seal) length is about 16.25".

 

Taking the same measurment on the Z31 halfshaft, I get 16", fully compressed (with inner cage reversed). Add to that, the thickness of the wheel side flange adapter (~1/2"), and the Z31 axle is completely bottomed out at 16.5".

 

Thus, the Z31 halfshaft would already be bottomed out on my 240Z sitting at stock ride height. Where have I gone wrong here? Obviously the setup is working for some people, I'd just like to know how.

[Drax240z]

If you consider the geometry of the Z (not ZX) suspension carefully' date=' it will become clear that the arc of the control arm actually pulls the hub in closer to the diff as it rotates down. Have you ever noticed that when you jack up a Z, the wheels drag inward as the car rises? Or, conversely, when you drop a Z back down to the ground, it looks like it has a lift kit installed untill you roll the car a few feet?

 

Nigel

'73 240ZT[/quote']

 

 

Still pondering this one a bit. I realize the above statement you made there is the case, but I don't think that necessarily indicates what happens with the halfshaft. In both bounce and droop the wheel will move inwards towards the center of the car. (ie: when the control arm is above, or below horizontal) However, because the halfshaft isn't on the same instant center as the control arm, the halfshaft length does not change at the same rate, or necessarily in the same manner... unless my reasoning is incorrect. I'm half asleep, so it may well be!

[wheelman]

Sean73,

I have the Modern Motorsport modified flanges on my car right now and they do not add 1/2" to the length of the axle. The original 240 or 280 flange is inset into the adapter so that the outside surface (closest to the wheel) is flush with the same surface of the adapter. There is a little length gained when the adapter is welded to the flange due to it's thickness but not enough to cause binding.

I've run my rear suspension through it's full range on both driver and passenger sides with no binding. I have a 1973 240Z with an R200 and CV axles from a 1984 300ZX Turbo with Ross's adapters and followed the instructions to reverse the cages. It works as advertised.

 

Drax,

Speeder's rear is definitely not at stock ride height and looking at the differing pivot points of the CA and the axle/halfshaft I believe Nigel is correct. Once the CA passes horizontal going toward droop it's arc is tighter than the halfshaft and is pulling the hub toward the center of the car thus shortening the halfshaft. The situation appears to be even worse as the CA passes horizontal in bump. The halfshaft should be at it's maximum length when the CA is horizontal. At least thats how it looks to me.

 

Edit: Drax, You ammended your post before I submitted mine. I think we're saying the same thing. Because the pivot points are different the rate of change will be different but the halfshaft gets shorter in droop and bump.

 

Wheelman