Jump to content
HybridZ

M2 Z31 Short shaft issue


SUNNY Z

Recommended Posts

Little back story:

 

LS1 / T56 280z

Chequered Flag racing 39 spline stub axles & companion flanges

Z31 Turbo cv shafts

M2 shorter shafts

Welded R200

Car is pretty low

approximately 450# of passengers and equip @ the time

 

 

Got these all installed, took it to the tuner, and he took it out for some data logging. He rolled into it at about 30, and at about 6K the car took a hard left, nearly lost control, and then made horrendous sounds while turning.

 

Took it apart today, and found that the outer CV on the driver's side had "failed". What happened was the inner star part of the cv (splined, fits on shaft) had been forced too far onto (inboard) the shaft, and stayed there. It was approximately 1/8" too far on. This then caused the cv assembly to pull out of the "cup" and ruin the boot.

 

Here's the kicker - The car was only powering 1 wheel afterward (passenger).

 

I took the rear apart, and the welds are intact, and both shafts turn when one turns. The cv was in otherwise great condition, and no other damage (including the passenger axle) was present.

 

I am super confused, and have no other ideas on this.

 

Maybe the shaft bottomed out, and caused this, maybe???? Idk

 

Here's a pic of the shaft - you can see where the star piece worked its way onto the shaft.

 

2012-07-08_23-09-08_852.jpg

Edited by SUNNY Z
Link to comment
Share on other sites

  • Replies 95
  • Created
  • Last Reply

Top Posters In This Topic

If the inner part of the CV pulled out of the cup, that means that the shaft is too short on that side. I don't see any other way that could happen. Jay Hitchcock had similar problems with a 280ZXT CV shaft that he had made to the wrong specifications. He had another set made longer (but still shorter than stock) and solved his problem. I'd like to see what happened to your shaft, maybe you could send it to me. There is a little bit of slack designed into the splines, and so the inner race can move a little bit (.050 or so is totally normal), but it shouldn't be jammed 1/8" up the splines. I have a feeling that may have happened after the joint came out of the cup.

 

The question is: Why is the shaft too short in your car? Do you have aftermarket control arms which are longer than stock? I don't think camber bushings would allow enough travel to be a problem, but are you running them, or anything else that might cause the distance from the stub axle to the diff to change? Since the LH is the side with the problem, it's impossible that you could have put the short shaft on the wrong side.

 

What was the distance that you had between CV and the adapter when you bolted it on? Should be about 3/4" and that should be right in the middle of the CV's travel. Since there is only about 3/8" of movement of the CV in the cup as the suspension moves, it seems very unlikely that the CV could disconnect from the cup if everything else was correct.

Edited by JMortensen
Link to comment
Share on other sites

Did you get your companion flanges from JMortensen or from some other source? I think you have those 39 spline stub axle kits. Could the stub axle to companion flange to outer CV stack-up be shorter than it needs to be? That could be another source of incompatability...that test fitting excercise throught the full range of suspension travel is so very important...another step, but an important one. I'm with JMortenesen - I think the jamming up the splines may have happened as a subsequent random act of violence after the actual failure.

 

JMortensen - on the cases that you have seen when the cage is bottoming out due to long shafts: did those folks have damage to their little tin "end caps?" I would think that they would be beaten up a bit. Sunny has not cap damage, so I can't imagine that the shafts are too long.

Link to comment
Share on other sites

I've never personally bottomed the shafts so I haven't seen the dust caps after that, but I've read about them being getting chewed up. I think the shaft hits the stub axle pretty quickly, so it's more of a dent in the middle of the cap. I figured out that the length of the CV was a problem on my own car and made my control arms longer (I was building new control arms anyway to go to heims joints).

 

A little bit about what we know: Josey has stock control arms and camber plates, and poly bushings, so I don't think that any of that is a likely culprit. I'm sure that the CV was pushed up the shaft when the two pieces were separated and binding on each other. It seems like the CV was able to pull out just far enough for the joint to spin inside the boot, but not far enough to come all the way out, this really sounds like Jay Hitchcock's experience. I tried to find his thread from probably 7 or 8 years ago and couldn't locate it unfortunately. Jay's was actually short enough to separate completely and so the tripod end of the CV was flopping around in the suspension.

 

Josey says that he measured from the diff to the companion flange and he thought that it was the same distance on both sides, which is not what we've found on 240s that have been measured, and not what could be seen on Carjway's 280Z either. Carjway's car matched my expectations exactly. So maybe there is a later version of the 280 chassis which has the diff moved 3/4" to the right... ??? I believe all the mustache bars are the same, so that would mean that the studs that the bar hangs from would have to be offset. Other than that, I'm not really seeing how this could happen. I've asked him to reinstall the CV, pull the CV all the way back from the companion flange and measure the gap. If the gap is greater than about 7/8", then we know something is funky on his car. If it is 7/8" like the others, then we have to try and understand what could possibly have moved so far, because there should have been another 13/16" of engagement (1 11/16" total CV movement available), so either the strut had to move outward that far or the diff had to move to the passenger side that far for the CV to pop out. At this point I don't see how either of those things could possibly happen. He also says his car is not obviously damaged, so it doesn't appear that this car was hit hard in the rear and then fixed badly.

 

If anyone would like to double check this issue, disconnect the CV from the adapter via the 4 bolts and measure the space with the CV bottomed and make sure you're in the middle of the range. I've got a 300ZXT outer CV cage in my office here, and you can clearly see that the shiny wear spot from it's original tour of duty on a Z31 is right in the middle of the cage (pic below), so I don't think that there is any question that the joint is designed to be run in the middle where these shafts are intended to put it.

post-553-005876000 1341856534_thumb.jpg

Link to comment
Share on other sites

I just wanted to pop in here real quick and say that jon and i spoke earlier, and i gave him some measurements. We determined that my drivers side shaft was indeed too short. I had 1.5" between the companion flange and the outer edge of the cv. I then ( per jons recommendation) put the stock z31 drivers shaft. I then measured the gap again, and had just over 1/4" , which may not be ideal, but it does work, as i took it for a test drive after, with no ill effects.

Link to comment
Share on other sites

I had about 1/4" of slack also, maybe a little less, so my balls probably aren't riding right in the middle (did I really say that?). In my 240z, both sides had about the same amount of slack. From my measurements, flipping the cages shortens the assembly an additional 1/8", which may have made the difference between having room to install my axles and not. Josey, you back on the road already? You are an animal! Post us a video with "one tire on fire."

 

JMortensen personally called me tonight to ensure that I had everything installed properly because my measurements didn't jive with his (imagine, a parts supplier doing a follow up phone call)! For clarification: I had only 1/4" of slack between because I have shortened control arms (13.5 inches in length instead of 14.5") and camber plates pushed in about an inch. How much room each of us will have will depend somewhat on control arm length, the presence of offset bushings, camber plate adjustment and perhaps even toe. I think that ride height will make a difference too: if your car is at stock ride height, the CVs will collapse under load and that if your car is lowered appreciably, then the CV will extend under load (squat). That is why a free end-travel test is indicated before final assembly. I plan to recheck free end-travel anytime I make a significant camber or track adjustment (at least the first time I make that change).

Edited by RebekahsZ
Link to comment
Share on other sites

The question remains, was Josey's car tweaked or bent, or is it manufactured differently than the earlier 280Z like Carjway has? I really don't expect that the car is built differently, because so many people use the mustache bars and the link for the rear control arm bushings out of the 280s on 240s that you would figure that this would have come up sooner if those parts were different. The weirdest part about Josey's situation is that the passenger's side shaft fits correctly, but the driver's side is too short. This doesn't make a whole lot of sense to me. Still, the situation is a bit worrisome and I'd hate to see someone else having this problem.

 

We're going to contact our customers who have purchased these shafts and ask that they disconnect the CV from the companion flange and measure the gap, and add that as a step in the instructions. If the gap is greater than 1 inch, we can swap out the short shaft for the long shaft at no cost, or they can run the stock driver's side shaft on the passenger's side and the M2 passenger on the driver's side.

Link to comment
Share on other sites

 

JMortensen personally called me tonight to ensure that I had everything installed properly because my measurements didn't jive with his (imagine, a parts supplier doing a follow up phone call)!

 

Same here. He is a stand up guy and it is too bad there are not more guys like him making Z parts.

 

I hope Sunny's car gets figured out.

Link to comment
Share on other sites

I have had this EXACT type of damage in my car; only I thought I had broken the cage and everything went to hell...this is not the case, looking at the outer CV cup in the photo above. The damage in my case, is caused SOLELY by having the CV axle pull itself apart. The top edge of the CV cup, that you see in Jmortensens's photo, has a ring pounded into it from the balls riding on the edges of the races, and it is slightly expanded.(his is not damaged that I can tell...but mine sure is, after seeing another one.) Turned out that the broken cage assembly was a result of the CV pulling apart under power.

 

I had exactly the same problem as the OP, but I am not using M2's axles, I made my own and mis-measured. Same terrible noises...but since I had an open diff, I just rolled backward down the hill into the parking lot and called the tow truck. Gotta measure correctly, folks!

Edited by Xnke
Link to comment
Share on other sites

We're going to contact our customers who have purchased these shafts and ask that they disconnect the CV from the companion flange and measure the gap, and add that as a step in the instructions. If the gap is greater than 1 inch, we can swap out the short shaft for the long shaft at no cost, or they can run the stock driver's side shaft on the passenger's side and the M2 passenger on the driver's side.

 

I measured my setup and got about ~3/4 inch gap on both sides with the suspension fully unloaded (full droop). The car is a '72 with Modern Motorsports adapter flanges, R200 LSD, stock LCAs, polyurethane bushings and no camber plates.

Edited by rossman
Link to comment
Share on other sites

I measured my setup and got about ~3/4 inch gap on both sides with the suspension fully unloaded (full droop). The car is a '72 with Modern Motorsports adapter flanges, R200 LSD, stock LCAs, polyurethane bushings and no camber plates.

Cool. I'll take you off the list of people to call. Still have about 20 calls to make.

Link to comment
Share on other sites

I jacked my car up and put stands underneath it. Then I removed the tires. I lowered the adjustable spring perch (sp?) on my coilovers and put a jack under the spindle pin. I removed the 4 bolts that attach the outer CV to the companion flange. Then I progressively jacked the spindle pin up from full droop to fully compressed while holding the outer CV to ensure that the clearance between it and the companion flange never bottomed out against one another throughout the entire range of travel. Everything checked out, so I put it all back together and went to the dragstrip. I'm resting easily at night knowing that there are no axle clearance issues.

Link to comment
Share on other sites

I have had this EXACT type of damage in my car; only I thought I had broken the cage and everything went to hell...this is not the case, looking at the outer CV cup in the photo above. The damage in my case, is caused SOLELY by having the CV axle pull itself apart. The top edge of the CV cup, that you see in Jmortensens's photo, has a ring pounded into it from the balls riding on the edges of the races, and it is slightly expanded.(his is not damaged that I can tell...but mine sure is, after seeing another one.) Turned out that the broken cage assembly was a result of the CV pulling apart under power.

 

I had exactly the same problem as the OP, but I am not using M2's axles, I made my own and mis-measured. Same terrible noises...but since I had an open diff, I just rolled backward down the hill into the parking lot and called the tow truck. Gotta measure correctly, folks!

 

So, This?

 

2012-07-09_13-36-41_702.jpg

 

This is what happened to mine. (ruined one on left)

 

Keith, after I inspected the welded diff, It had no issues, so I put fresh oil back in it, and installed it. So, yes, I do have it back on the road. And WOW, it is a torque MONSTER. I was amazed how well it actually did hook up. It blows the 275's off pretty good from a 20, hooks, hit second and they're ablaze again. It spins through most of second, but REALLY goes in third :blink:

Edited by SUNNY Z
Link to comment
Share on other sites

The Chequered Flag stuff is made by the same guys who make MM's parts. I have the 39 spline stubs and flanges from Ross on my car and I can tell you that the shafts were measured off of those pieces. It shouldn't matter if you have M2, Chequered Flag, or MM billet or welded adapters. They'll all work fine and be close to the middle of the travel (the MM welded parts will be offset about 3/8" to the exterior).

Link to comment
Share on other sites

Once you get some rest and get moved, I highly recommend some slicks. When you can actually get that torque to the ground it is even better (I do have to work out my handling issues with the slicks, but it is just awesome out of the hole). Congrats!

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


×
×
  • Create New...