CV Axle Discussion

[wheelman]

Jon,

I'm having a hard time making your numbers work.

Even in the best case the original passenger side shouldn't have fit at all.

 

15.875" = length of passenger shaft

1.25" = 1 spline length

1.687" = depth of CV housing.

Available length = 12" according to your measurements

 

15.875" - 1.25" - 1.687" = 12.938"

12.938" - 12" = .938"

 

I used 1 spline length because the outer splines protrude through the cage and it's actually the end of the shaft that contacts the cap on the outer CV housing when the cage is flipped.

 

Based on these numbers the original passenger side shaft should be .938" too long to fit at full bump which according to your numbers is the best case.

 

Doing the same thing with the drivers side shaft yields these results.

15.375" = length of driver shaft

1.25" = 1 spline length

1.687" = depth of CV housing.

Available length = 12" according to your measurements

 

15.375" - 1.25" - 1.687" = 12.438"

12.438" - 12" = .438"

 

This indicates the drivers shaft would be almost 1/2" to long, this is obviously not the case as I was able to install mine and actually move the shaft back and forth at full droop.

 

If you look at the pictures I posted in this thread

http://forums.hybridz.org/index.php/topic/72805-using-pathfinder-and-zxt-axles-to-install-30-spline-nismo-lsd-kit-56k/page__st__40

you'll see the outer CV housing is actually closer to 3" in depth.

Using that value instead illustrates how much space is available.

Here are the numbers for the drivers shaft

 

15.375" - 1.25" - 3" = 11.125"

11.125" - 12" = -.875"

 

In other words there is actually closer to 7/8" of clearance at full bump and 1/2" at full droop.

This would imply the passenger shaft would slightly bind at full droop, have 3/16" clearance at mid point and have 3/8" of clearance at full bump.

 

These numbers fit what I experienced. I run the welded flanges and my passenger axle was slightly bound up at mid-point until I cut 1/8" off the end of it and ran about 0* camber.

 

I looked at your numbers again, think I found the mistake that was confusing me. You used 2.125 instead of 2.5 to account for the spline length.

Correcting this makes the following equation:

11.635 + 2.5 + 1.6875 = 15.8125

15.8125 - 15.375 = .4375

 

So your numbers look very close to mine assuming the outer CV cage is not flipped.

[JMortensen]

Not following you entirely. I was using 2.125" because I have Ross's billet companion flanges, which give an extra 3/8" of clearance. I shortened the CV to make room for the thicker welded flange.

Edited July 13, 2011 by JMortensen

[JMortensen]

I talked to Ken (wheelman) on the phone last night and I think we got this pretty well figured out. I had calculated 1/16" of clearance, Ken said on his car he had between 1/8" and 1/4" clearance using the driver's side halfshaft on the passenger's side of the car. Where that discrepancy comes from is anyone's guess, but my car has so many variables (camber plates, poor man's toe adjuster, control arms, etc), his has camber plates too, and there may be some variation from chassis to chassis, and it's pretty tough to get a real accurate measurement in there because you have to bend the tape measure and it's in a weird spot, etc. If you use the 1/16" estimate from my calculations and take the middle of his estimate at 3/16", we're only 1/8" off of each other, so that's not too big a difference all things considered.

 

The question again is does his setup work without binding at all, and if he has 3/16" of clearance, I think the answer is probably yes. There might be some other factors which exacerbate the situation, like if you have aftermarket control arms that are shorter than stock or if your camber plates allow more neg camber than the ones on my car, etc. Also I think bushing compliance might be an issue, if you have stock rubber bushings they might give enough so that the CV's end up putting "some" pressure on the side of the diff. We both agreed that switching to my new shaft lengths poses no problems and would put the CV joint closer to the middle of the housing as well.

 

We also talked about people who have had limited slip differential damage due to the CV's bottoming, and he was originally under the impression that this pressure from the CV was compressing the clutch stack and that was somehow causing damage. I think the opposite is true, because when the clutch stack compresses it moves the side gear towards the wheel, and this pressure moves the side gear that the CV attaches to towards the center of the diff. Without having seen the innards of one of the diffs that suffered damage, I think there are a couple likely scenarios. First is that the CV puts a load on the side gears and that actually pushes really hard on the spider gears in the middle and then they are forced to turn on each other, so they give up. Second would be that the carrier bearings give up because the carrier is being pushed one way or the other (especially in a turn) instead of floating in the middle and the suspension taking side loads. Third is the carrier moves laterally due to side load changing backlash, so this may be what happens after your carrier bearings give up in the 2nd scenario, and this causes a problem with the ring and pinion engagement, and that causes damage. So those are my theories, I guess I'll have to see how accurate they are when someone produces photos of a damaged diff.

 

I'm going to sell the driver's side CV only and also sell the two CV's as a set, you guys can figure out if you want to move the stock driver's side to the passenger's side or just buy the set. Now I just have to wait for them to come so I can check fitment. I hate waiting.

[wheelman]

Jon,

I've been thinking about this and one more thing should be made clear.

 

If someone decides to use the drivers side 300ZXT axle on the passenger side they will still need to completely disassemble it in order to use the correct inner CV joint. The "stock" passenger side axle is the one with the longer splined section that inserts into the diff, this CV must stay on the passenger side of the car.

[Xnke]

Jon, have you looked into producing 30 spline stubs to use the Nismo LSD kits for the S13/14/15 R200 differentials? This would really make an LSD more available to the Datsun community, both in Z's and dimes alike.

 

(and I'm still really really looking for a R180 3.36 LSD option, but being broke doesn't make that realistic for a while)

[JMortensen]

I'd need a set of inner CV's, and an order for the complete kit to do it, but yeah, it could be done.

[JMortensen]

Just got a call from my supplier, they're expecting to ship my parts mid next week, so I won't get them until late next week or beginning of the following week.

[JMortensen]

Parts shipment delayed, now they're talking about shipping on 8/4 or 8/5.

[RACERZ]

Grettings I am new to the forum. We race with SCCA and have a EP 240Z. I have been looking into converting to a CV axle system and followed the progress of the discussion.

I have several questions if anyone could help (sorry if any of them are reduntent).

I was wondering if this application being dicussed is for the R180 or R200 diffs, we have to run the R180s and wondered if since the R180 is slightly narrower would there be less problems with shaft clearence or has anyone looked at the specs for the R180 diff vs R200?

Secondly has anyone compared the weight difference in the two systems since that is our main concern in converting (stock shaft hold up fine,just heavy).

Next we run a much lower setting on the race car vs street cars so the shaft angles will be different, has anyone checked binding at extreme angles (stock shafts are designed to be near vertical under full compression vs on our car they tend to start neutral and go positive during hard cornering)?

I have looked at several existing systems out there, and was told by other racers that they tend to blow up under racing conditions, I was not clear if the problems were due to binding vs stress loading during cornering? anyone heard about similar problems?

Thanks for any info.

[JMortensen]

The examples listed in this thread are for R200s. For R180s the only thing out there right now is the 930 CV adapter kits, where you have an aluminum adapter that bolts to the stub axle on the wheel and the stub axle on the diff and uses the Porsche 930 CV joint. I really doubt that any damage could be done to that joint by an EP car under any "normal" racing condition. I would expect that if there was a failure that it came from the adapter. I have heard of one instance of the adapters loosening up. Most of the problems that you hear about with road racers are with the stub axles failing.

 

I would think the CV system would be heavier than the stock halfshaft, but don't recall anyone actually weighing one vs the other.

 

CV's should be much less likely to bind, and that is one of the selling points that Todd @ Wolf Creek Racing is pushing. The U-joints on a really low 510 will actually start to "knuckle" and create a vibration just due to the angularity. The adapter/930 joint setup fixes that and he's actually seen dyno results showing a 3hp increase on a 510. I don't know if that would be the same on a Z, I suspect that there wouldn't be as much gain, but that's what he's shown for the 510.

 

Just to update I am still waiting on my prototype order to be shipped.

[Six_Shooter]

Just to go back to the original discussion for a minute.

 

I have been running the 300ZX axles in my car for over a year.

 

I made my own CV adapters, well my grandfather did, with my input. I purposely made sure they were as thin as possible, due to reading about some axle length issues, the main meat of them are still 3/8" think IIRC. The original companion flanges also had about 1/16" machined off the face of them, this was to create a lip to align the adapters, but it will help add a tiny bit of space, so I mention it.

 

When I first installed the axles, I flipped the cages, but didn't remember or didn't read about grinding the end of the axle, so I had issues getting the passenger side installed. I did it, but it was a chore. I then before lowering the car off the jack stands read about grinding the end of the axle. So out they came. I ground the axle end down to within an 1/8" of the retaining clip groove. I can now install the passenger side axle with ease. In fact I've had it bolted to and removed from the companion flange several times in the last couple months, due to my 5 lug and brake swap, and most recently installing my lowering springs. In each case, I was able to swing it out of the way without any issue.

 

My suspension:

Stock control arms

Stock upper strut attachment point

Tokico blue strut inserts

As of last weekend Eibach springs, stock springs before that.

R200 from a Z31

280Z R200 mustache bar

Original ('73) uprights, front diff crossmember

solid front diff mount

 

As far as I know the car has never been in a serious accident.

 

I have no issues with the axle bottoming out. The grease cap had a dent from the first time I installed it and it doesn't appear to have been made any worse while driving it. I don't get any weird handling issues, no clunks, at least non that were not there before I put the axles in. lol

 

I haven't removed the springs to check for bind, but with the earlier info provided, if they fit in at full droop, there will only be more clearance when the car is on the ground, so I am not worried about it in the least.

 

I do need custom length axles in the not too distant future for an LSD swap, though, that is a different thread all together.

[chrism]

I used 300zx axles and had them it shortened to fit both sides. Here is a pic of the modification. I have enough travel that it won't bottom out.

I sent my axles to Performance cryogenics. website is http://www.performancecryogenics.com The guys name is Dean. They mostly mod rock crawler axles for jeeps and 4 wheel drives.

Email is performancecryo@mindsync.com . They can even put your axles through cryogenics to make them much stronger. They will be the last thing that breaks.

$65 per axle to re-spline and also add the clip groove at the end.

$100 per axle to run through Cryogenics.

 

It's not a very precise picture with exact measurements but it was good enough for what I needed. This is for the longer axle.

I don't have a pic of the shorter axle but you get the idea. Misspelled Spline also. So shoot me.

If you have a set of 300zx axles, you will see that there are thicker spots along the shaft in the right location for resplining.

 

I would post pictures but I was so excited when the axles came back that they went together and in the car. So I forgot.

They look great and the tri-bearings were very smooth moving up and down the splines. No play.

I live in NC and Performance Cryogenics is in CA. Took only two weeks from the time I shipped them to the time they shipped them back.

Dean always answers his emails. He doesn't care if you can't spell. They don't mess around.

Edited August 10, 2011 by chrism

[JMortensen]

It's not a very precise picture with exact measurements but it was good enough for what I needed. This is for the longer axle.

I don't have a pic of the shorter axle but you get the idea. Misspelled Spline also. So shoot me.

If you have a set of 300zx axles, you will see that there are thicker spots along the shaft in the right location for resplining.

 

Couple issues I have with what you wrote there. Only the outer CV shaft can move on the 300ZXT CV. The inner can pivot but cannot move in and out to change the length of the shaft. I listed the travel spec earlier in the thread at 1 11/16" inches. If you shortened the shaft as much as you suggested, it would be way too short to bolt up. Mine do not have enough meat in the area where you would need to respline according to my measurements. I posted a picture earlier in the thread of that as well. You also mention tripod bearings, but the 300ZXT has CV, not tripod bearings. Maybe you're talking about a 300ZX NA shaft which has the tripod bearings, and they are different. I don't know, but I'd hate for someone to go have their ZXT axles shortened to the point of uselessness though.

 

EDIT--Did you use a much thicker adapter to bolt the CV shaft to, possibly?

Edited August 10, 2011 by JMortensen

[Xnke]

No, he used 300ZX non-turbo axles.

[chrism]

I have a J30 DIFF, From there I used the J30 tripod bearing housing. 300ZX (NA) axle then a 240sx Tripod bearing housing to the modern motor sports adapter with the double bolt three position bolt pattern.

No thicker adapters.

There was enough room for the springs inside each CV axle. I didn't have to grind anything. Just put it together and install.

Axle does not bottom out or try to pull apart when the wheel assembly is raised all the way up or lowered all the way down.

Works good for me.

[CarJway]

Jon, I know you were waiting on the axles to be shipped... Any new updates? I am eager to get my hands on a set, once you confirm the prototypes are good.

[JMortensen]

Today is the 42nd day since I placed my order for the prototypes. I've emailed the manufacturer, no response. I'm sorry for the delays. I was told 7-10 days originally. Just left another message for them as well.

Edited August 19, 2011 by JMortensen

[JMortensen]

Just got a call, they're shipping my order today.

[Xnke]

Heh, remember the rule of real time verses machine shop time...I'm a hobby machinist and know it well.

 

One hour = one day

one day = one week

one week = one month

 

And so on.

[JMortensen]

I got my order. It included everything EXCEPT the short CV axles. I tried to get a hold of the machinist today, no luck. Hopefully Monday. I'm going to have to take some measurements and talk to him before I advertise the new CV kit, but it looks awesome.