M2 Z31 Short shaft issue

[matt_w]

Jon, I just measured mine. These are approximate (it's hard to hold everything in place and measure at the same time).

 

Full droop: drivers: 1", passengers: 7/8"

Ride height: drivers: 1 1/4", passengers: 1 1/8"

 

Is this an ok amount? If the CV allows 3" of play, wouldn't this put the balls right in the middle? I am running 480 ft/lbs of torque.

[JMortensen]

The CV has 1 11/16" of total movement. The housing is 2 13/16" tall, and the inner race is 1 1/8" tall, so the total range of motion of the balls as measured from their center is from 5/8" away from the bottom of the cup to 2 3/16" from the top of the cup. 1.25" of free space means that you will have the center of the balls about 15/16" from the snap ring groove.

 

The wear pattern on my 300ZXT outer is centered at 1 1/16" from the groove and you're at 15/16" which is almost identical. Obviously we can't vouch for the used CV joints or anything else on your car as they weren't supplied by us.

Edited July 11, 2012 by JMortensen

[matt_w]

Are those numbers with the cage in the original position? (Not that it matters too terribly much, I didn't flip mine though).

 

So everything "should" be ok for me, right? Just want to make sure before I bolt everything back up.

Edited July 11, 2012 by matt_w

[JMortensen]

The cage won't change the position of the balls, because the balls still ride in the middle of the race regardless of which orientation the cage is in. Based on the info you've given I think you're good to go, you're pretty well centered in the joint.

[JMortensen]

OK guys, we have another problem. I was writing up installation instructions and I came across a picture that shows exactly what matt_w just asked, and it is pretty clear that the balls do NOT ride in the center of the race. After seeing this I went out to the garage and took a look, and figured out that all of my measurements are off because of this discrepancy. The balls are about 1/8" farther to the outside of the CV cage than I had figured, and the available travel is about 1 3/8", not 1 11/16. We don't think that the CV's will top out because of the minimal amount of CV travel, but it's close enough that we don't want to let it go. Therefore we're going to do a recall. We are going to recall the driver's side shaft and customers will use the M2 passenger side shaft on the driver's side. A new passenger side will be made 1/2" longer and will be replaced free of charge. Of course, we have to order the new shafts so there will be a delay.

 

For those who need to use their car right away, the stock driver's side shaft is 1/2" longer than the passenger M2 shaft, so you can swap the passenger side M2 to the driver's side of the car and run the stock driver's shaft on the passenger's side and that should put the balls right in the middle, although the shafts won't be chromoly. Any customer who would prefer to use the stock shaft with our long shaft can have a 50% refund.

 

I apologize for the inconvenience, and I will again try to contact everyone who purchased these shafts (again) to let them know of the problem and our solution to it.

[matt_w]

Any idea on the lead time to new shafts? I assume you want to hear back from everyone before ordering them.

[JMortensen]

Yes, I would like to hear from as many as possible as quickly as possible. I'm checking on the lead time on new shafts.

 

Our conservative "safe zone" on these shafts is going to be from 1/8" at full droop out to 1.125". At 1.125" the balls are riding about 5/8" down below the outer snap ring with the shaft straight. Even at 1.25" the balls are down in the cup 1/2". They're really not that close to the end. The problem is that there is angularity at the CV which moves 1/2 of the bearings closer to the end of the CV and 1/2 farther away, and this angularity will vary from car to car. The angularity is less of an issue at full bump because the CV joint gets straighter as it approaches full bump (this is why the shafts need to be shortest at droop) so we are really erring on the side of being cautious. Part of the idea behind these shafts was that people would be able to lengthen the control arms as well. Our measurements were wrong and biased the ball bearings further out in the CV joint than we had intended, and we also found that the CV joint has less plunge available than previously figured. These shafts should not have issues on a "normal" Z car, the problem is that people who will buy this product don't have "normal" cars.

 

I know that there may be some loss of confidence in my ability to figure this out, so I encourage everyone to double check me yourselves. Instead of taking the measurement of the parts when disassembled and then figuring out the stroke in the CV with math, this time I've assembled the CV and used physical spacers underneath the cage of the CV to figure out where the balls will be with the shaft on a bench.

[JMortensen]

Lead time on new shafts is 3 weeks.

[superduner]

Thanks for the update Jim, kudos for the honesty and fast communication regarding the problem. Quick question out though, I put together the shafts yesterday and installed them and the car (suspension wise) other than urethane bushings is stock. Springs and all.... And the car is on the ground and able to roll, with the car on the ground installing the cv's what's the ideal gap between the shaft and the hub adapter that would be ideal with the cv shafts pushed in and compressed toward the diff? Ican honestly say they seem to fit perfectly with a nice amount of space for travel. I only measured the gap of the driver side so far and I got just a small line over 1"

 

Feedback anyone?

[JMortensen]

Middle of the travel is about 5/8" gap, so we're really not that far off from where we need to be, but we need to remember that droop is the start point. So if you start at 7/8, you're already 1/4" past the center and moving further inboard as the suspension compresses. On my car I got 3/8" of movement, so you're 5/8 past the center at full bump if your car measures out the same. Assuming that you're using stock control arms, you really shouldn't get near the end of the travel, as I said before, but there are variables that we can't take into account like camber bushings, longer control arms, camber plates, etc. By swapping the shafts, you'll start with about 1/4" gap and at full bump that should be about 5/8", right in the middle, but you'll have room for camber bushings and longer control arms, etc. and if you're putting down huge amounts of power you won't be close to the end of the cup, where the groove for the CV clamp is machined in.

Edited July 12, 2012 by JMortensen

[superduner]

Lol sorry kind of ignorant on some of the terms like middle of travel or droop so I'm not sure where middle of travel is considered :/ I get the feeling it's when the car is normally sitting on the ground? Anyway... Il take some measurements and pictures of the driver/pass side gaps with the car leveled on the ground and up In the air, hopefully i can get some feedback as to where I stand in regards to whether or not it's ok to drive my car with stock arms and no camber plates. I plan on putting shorter springs an illuminas in the future though. Not sure that would help or harm with these shafts... Stand by for pics and measurements

Edited July 12, 2012 by superduner

[JMortensen]

When you jack the car up the suspension droops and the struts extend all the way. Full bump is when it is all the way compressed. We're being cautious with our measurements and we're doing a recall, so I would suggest that you don't drive it.

[RebekahsZ]

Dropped ET to 7.2 at 96mph (1/8 mile) with these axles on bias ply slicks with LS2/T56. That is 9 runs without issues.

[johnc]

for staying on top of this Jon. Z product development is a pain in the ass sometimes.

[900ss]

We are going to recall the driver's side shaft and customers will use the M2 passenger side shaft on the driver's side.

A new passenger side will be made 1/2" longer and will be replaced free of charge.

 

 

Ok this was a few months back when I took these pics and my cars since done 270 odd "mile" since then. But better to be safe then sorry

First my cars a UK spec RHD 260z so I haveto think the other side to you guys

All of this is based on LHD OR RHD terminology aswell

But I still cant get my head around this

Pics 1 & 2 below show my shafts reversed when I first tried them over 3 mths back

When around the wrong way no way would the drivers fit

As you can see the driver side (my passengers) is too long.

 

Pics taken at full drop without outer cv fitted

 

 

 

Pics 3 & 4 below show them around the right way imo

 

 

 

 

Now if I refit the passenger shaft (my driver side) back to the drivers side it will become too long again ?

As far as I can see they are right as they are ?

 

Or am I very wrong ????

[JMortensen]

I've got instructions done and I'm going to email them out to everyone and they describe how to measure the CV free play. I haven't tried to figure out the length of the shaft to the flange without considering the CV, so I can't say what the correct dimensions would be when doing it that way. I can say that the right side shaft on the US cars has a longer spline on it and if you put it on the left side and installed it until it clicked into the diff, the inner CV would be about 3/8" farther out than it would be installing the correct length left side. That in itself could throw everything else off. We're anticipating 1/4" to 3/8" of clearance, so if you start with 3/8" less space, you might be inclined to think that it won't fit at all.

[900ss]

I can say that the right side shaft on the US cars has a longer spline on it and if you put it on the left side and installed it until it clicked into the diff, the inner CV would be about 3/8" farther out than it would be installing the correct length left side. That in itself could throw everything else off. We're anticipating 1/4" to 3/8" of clearance.

 

Yes I realise that and am 100% sure I didn't have the inner CV on the wrong side

As you say if fitted to the wrong side it then doesn't allow the inner CV shaft to fit correctly into diff.

 

 

(Yes I also tried that aswell)

One side would end up sitting wide when fitted wrong aswell as no doubt leak the diff oil out !!

Edited July 20, 2012 by 900ss

[DatRat]

Jon, I spoke to you on the phone about a week ago. I finally had a chance to measure the cv free play on my 77' 280Z with after market control arms. However, when I measured the free play, the control arm length was set to 14.5" (stock measurement). My measurements are almost identical to the measurements matt_z reported. I can understand the concern people are expressing with regard to the position of the ball bearing carriage inside the housing. With my measurements, I probably don't have a whole lot of camber adjustability beyond the stock position. Anyhow, I think the new axles will correct the issue. You have been a real stand up guy throughout the whole process and I would certainly do business with you again in the future.

[JMortensen]

So that's a 77 that has the same measurements as everything else. Thanks very much for reporting back. I am 99% convinced that all S30 Z's have the same dimensions back there, and that Josey's issue was due to a bent suspension piece or tweaked chassis. I don't think we have another customer with a 78 to check but it seems unlikely that they would change the dimension only on the driver's side for one year only.

 

I really appreciate the feedback, and thanks for the support.

[SUNNY Z]

I still swear up and down that my car is accident free. I have no idea why my measurements were so much different, but they were! The car aligned great, and didn't differ from side to side at all. It drives straight as an arrow. One of life's little mysteries!