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Axle problems


Harvey

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R200, checkered flag stubs and hub adapters, and z31 cv axles. And I have been reading up all night about how z31 na axles are to long. So now the question is shorter axles or adjustable LCA's. Or start from scratch.

 

So if you read all that, why did you need this thread?

 

And NA axles? You sure thats what you have? As far as I know, no one makes a companion flange for NA axles. Turbo, yes.

 

.... Just saying, the info is out there, if you're willing to look.

Edited by SUNNY Z
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Well I purchased some parts from a person on here who said it was one thing and turned out being another, when you get a box of axle parts and are trying to piece it together. Mistakes can happen and don't need a lecture. My biggest question was how much do you gain by flipping the cages. I'm sorry if I'm wasting anyone's time.

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About 1/3 to 1/2 way down JMortensen's "Differential/..." page there is a comment about the NA 300ZX CV shafts being too long. Sounds like you got a pair of those. There's also a comment about the six bolt adapter at MM. I'm fairly certain that the six bolt pattern for the Z31 NA is the same as the six bolt pattern for the S130. You could get some 280ZX CV half-shafts and they should fit your MM adapters and be the right length. The 280ZX turbos and some NA cars came with the CV shafts. It does get confusing, especially if you start looking at hybrid CV shafts, hub options and differential setups. Lots of options and none very easy.

 

http://forums.hybridz.org/index.php/topic/49194-differential-cv-lsd-hp-torque-r160-r180-r200-r230-diff-mount/

 

From the page:

 

"The CV shafts first made their appearance in the Z line with the 280ZXT. This car got the tripod style CVs which have 3 large rollers arranged 120 degrees apart from each other. The 280ZXT CV’s are more durable than the halfshafts and are a good upgrade. www.modern-motorsports.com makes an adapter which allows the CV shaft to be bolted to the companion flange on the stub axle (the wheel side connection for the halfshaft). The 280ZXT CV plugs into an open or CLSD R200. These CV joints have bulky housings and can interfere with rear swaybar end links. Some have simply put smaller end links on to get around this issue.

 

280ZXT CV shafts:

 

Resized to 20% (was 512 x 384) - Click image to enlarge

 

 

The Z31 got a different, stronger CV shaft. In addition to being stronger, the housing for the CV joint is smaller in diameter, and this means that it interferes with sway bar end links less. There are two different Z31 CV shafts. The normally aspirated Z31 uses a 6 bolt shaft. For whatever reason, these shafts are too long to be used in the S30 chassis. Don’t get NA Z31 shafts. The Z31 turbo shafts have 4 bolts, and they are the right size to fit into the S30, using companion flange adapters from www.modern-motorsports.com."

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If you have 4 bolt shafts, talk to Joe at Chequered Flag about shorter CV shafts, he wanted to make them and he has the other parts (stub axles and companion flanges) already in production. If you have 6 bolt adapters, look at the 280ZXT shafts. I don't know if the 280ZXT shafts fit without issues or not, haven't tried them personally.

 

I can tell you that the Z31T shafts don't fit, and flipping the cages won't fix it (flipping cages gives you more like 1/8" extra clearance). Really needs shorter shafts, which I made for a while but shut down the diff biz just a week ago or so now.

Edited by JMortensen
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Why we beating up a brother? When I rebuilt my 4-bolt cv axles and did the m2 short shaft conversion, I flipped my cages. Flipping the cages shortened my axles an additional 1/8" (I measured). So, I'm confirming what JMortensen said above. If you are autocrossing lengthened LCAs are ok, cause you need about 3 degrees neg camber anyway, but if you are gonna shock the drivetrain with drag race style driving, you really should limit rear camber, so lengthening the rear LCAs ain't such a good concept at least in theory. See if JMortensen has any short shafts left that he can sell you. If not, try pm-ing Sunnyz to learn about the driveshaft shop shortened axles or contact them directly. My m2 axles have about 40 passes on them and are doing fine, but my LS2 motor is stock, not making near the power that some of the other cars on this forum are making. Best of luck with your project.

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If you have 4 bolt shafts, talk to Joe at Chequered Flag about shorter CV shafts, he wanted to make them and he has the other parts (stub axles and companion flanges) already in production. If you have 6 bolt adapters, look at the 280ZXT shafts. I don't know if the 280ZXT shafts fit without issues or not, haven't tried them personally.

 

I can tell you that the Z31T shafts don't fit, and flipping the cages won't fix it (flipping cages gives you more like 1/8" extra clearance). Really needs shorter shafts, which I made for a while but shut down the diff biz just a week ago or so now.

 

Flipping the cages in my axles worked flawlessly.

 

I'm still trying to wrap my head around the idea of the axle binding at ANY point in the suspension travel, when the tires are on the road.

 

It has been stated that the shortest distance between the companion flange and the diff, is at full droop, and that this distance only increases as the suspension compresses, so where does this "bind" come from?

 

I've been running stock turbo Z31 axles in my '73 240Z with home made companion flange adapters for a few years now, without issue.

 

Flipping the cages, and trimming the end of the axle shaft itself, allowed me to install the axles without issue. I did actually get the driver side in, without flipping the cages, but was tight to do so, it was only when I went to install the passenger side that I found out that the cages needed to be flipped.

 

The hardest part is getting the passenger side axle in and out, since that is the tightest side, when the suspension is at full droop. Also on mine, that seems to be the side that got the companion flange adapter that fits more snug on the outer CV locating ring, so I need to use a little more persuasion if I ever need to remove it. ;)

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It has been stated that the shortest distance between the companion flange and the diff, is at full droop, and that this distance only increases as the suspension compresses, so where does this "bind" come from?

 

I've been running stock turbo Z31 axles in my '73 240Z with home made companion flange adapters for a few years now, without issue.

I measured on my car and the measurements off of all of the people I talked to (quite a few M2 customers who gave me the validating measurements off of their own cars with M2 shafts installed) indicate that the stock shafts are too long to fit without some modification. When I figured this out on my own car, I lengthened the control arms 1/2", and I had the MM billet adapters, which give you 3/8" more clearance over MM's welded adapters. IIRC, the stock shafts were something like 5/8" or 3/4" longer than should fit with the MM welded adapters.

 

My best guess is that your companion flange adapters must be narrower than the MM ones. I still have no idea what most of the people who were running the Z31 shafts were doing. I know a few were making their own adapters and running Pathfinder shafts, but the majority must have been forcing them in place and then driving around with the rear suspension all bound up.

 

 

 

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Oh, we've beaten this to death...

Seems not every car is the same. My LCAs are shortened 1/2" from stock 240z. My M2 axle shafts are 1" and 1-1/8" shorter than stock Z31. There is no way that I could have used stock shafts with stock axle shafts with either my shortened LCAs or stock LCAs, so I'm backing JMortensen. But, I think everybody's situation is different, so we should all strive to measure for our particular car setup. Be sure to mock up before final assembly: remove your coil springs and jack the suspension from full droop to full compression to ensure that the axle still has a little slack (but not too much) before bottoming out (binding) on the companion flange adapter. M2 did a great job for me; I hope the Driveshaft Shop can supply my future needs.

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It has been stated that the shortest distance between the companion flange and the diff, is at full droop, and that this distance only increases as the suspension compresses, so where does this "bind" come from?

 

 

The attached picture suggests that full droop actually lengthens the half-shaft and suspension compression shortens the shafts (I'm using "half-shaft" to describe both styles, CV and u-joint). This might explain a few things. A car lowered to allow compression beyond the factory design could bind the shafts. It could also be that Nissan designed the loose rubber mounting on the differential to allow sideways movement under extreme suspension compression.

 

The drawing is from the 1976 RA chapter, but I assume that the 240Zs are the same. Someone with some drawing skills could probably calculate the amount of movement based on the arcs of travel of the link and the axle.

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It has been stated that the shortest distance between the companion flange and the diff, is at full droop, and that this distance only increases as the suspension compresses, so where does this "bind" come from?

 

 

(Edited several times after staring at the drawing)

 

The attached picture suggests that full droop actually lengthens the half-shaft and suspension compression shortens the shafts (I'm using "half-shaft" to describe both styles, CV and u-joint). This might explain a few things. A car lowered to allow compression beyond the factory design could bind the shafts.

 

The drawing is from the 1976 RA chapter, but I assume that the 240Zs are the same. Someone with some drawing skills could probably calculate the amount of movement based on the arcs of travel of the link and the axle.

 

 

More food for thought - It could be that Nissan designed the loose rubber mounting on the differential to allow sideways movement under extreme suspension compression to avoid binding. I've always wondered why the mustache bar rubber was so loose.

post-8864-037599900 1351050908_thumb.jpg

Edited by NewZed
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The attached picture suggests that full droop actually lengthens the half-shaft and suspension compression shortens the shafts (I'm using "half-shaft" to describe both styles, CV and u-joint). This might explain a few things. A car lowered to allow compression beyond the factory design could bind the shafts. It looks like binding might in the middle of travel somewhere.

Ross said way back when that the shafts were shortest at full droop. When I measured for my shafts, I verified that to be the case. 3/8 of an inch total travel from full droop to full bump, shortest length was full droop. Since the stock axles are more than 3/8" too long, the stock length Z31 axles should never get out of a bind when forced into a S30 chassis.

 

The problem with considering the arc that the control arm moves in is that it doesn't account for the strut motion. The strut is essentially a sliding upper control arm. This is why camber continues to go negative even after the control arm passes horizontal.

Edited by JMortensen
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