Shortening CV Axles

[whatnow123]

So I have a set of Z31 turbo CV axles that have been staring at me in the garage and I have recently ordered the MM CV companion flanges. I have been reading about what it takes to install them (flip the bearing cages) and I have also read they are just a touch to long and load the ring gear in the rearend. I have a rock solid r200 LDS and don't want to F- it up.

 

Anyway, I took the CV's into work to flip the cages and got to looking at it. The bearing cages are held onto the shaft by a couple of C clips at both ends and then slides within the CV housing. After flipping the cage, the axle itself is now the longest point. I got to thinking about this, it's the CV axle shaft that makes contact with the stub axle causing the binding which in turn pushes against the diff and can wreck the ring gear/carrier bearings. This is why MM sells shorter axles (by 1/2 inch I believe).

So I got to thinking, why not just move the channels where the C clip secures the bearing cages and cut down the remaining axle? There is plenty of spline left on the axle for the bearing cage, the new grove I cut in the axle is still larger than the factory indentation for the CV boot, so I didn't compromise strength at all, so I'm not sure why no one has done/thought of this.

 

With that said and considering CV axles are way cheaper than a R200 LSD, I busted out the grinder and shortened the axles by about 5/8 of an inch. I made 2 new groves for the C-clips and I believe I have a very inexpensive solution to buying shorter axles.

 

I just wanted to post this and to see if anyone can chime in to a potential problem that I'm not seeing as this seems like very simple and cheap solution..

 

I stole a couple of photos from another web site as I didn't take a photo of what just flipping the cages looks like.

 

One is as it sits, the other is when it is flipped... and then on from there.

Edited November 14, 2014 by whatnow123

[NewZed]

Seems like it might work.  Good idea.  There are members though, that have pulled their axles out of the diff because they weren't long enough (it was a while ago and I can't remember the details.  Edit - actually I think that he ended up grinding some grooves like you did.).  You would just need to confirm that you have the travel to cover the range, shortest to longest.  

 

Here's the thread.  He actually did a couple of things.  Others chimed in with examples too.  Just a consideration, you might be fine.

 

http://forums.hybridz.org/topic/110723-q45-vlsd-tearing-up-cages/

Edited November 14, 2014 by NewZed

[RebekahsZ]

Looks good. Now install it and tell us how it works. I've thought about cutting mine but was afraid the cutting might hurt the heat treatment. One way to find out!

[gnosez]

OEM CVs once reversed are fine to use.  Aftermarket versions only came in one length with one side being too long for a R200 diff. How do I know this? I have a very polished 3:90 gear set and a nice bottle of gear oil with thousands of metal bits sitting on a shelf. A notice from Autozone concerning the recall of the aftermarket CVs and a set of OEM CVs that have over 10,000 hard driven miles that have not been cut or ground down.

[NewZed]

OEM CVs once reversed are fine to use. 

This might be true for 280Z's.  240Z's don't seem to have as much space between the flanges.  They bind u-joint half-shafts when R200's are installed.  (No actual experience, just repeating internet info from reliable sources).

 

I'm surprised that this hasn't been proposed before.  If there's enough spline on the inboard side, you should be able to recreate the custom shafts' dimensions, as seems to have been done here. 

Edited November 15, 2014 by NewZed

[whatnow123]

REB,

It won't hurt the heat treatment and it's on the very end of the shaft so it wouldn't really effect the shaft. Also, if you look at the 4th photo, the "weak link" would be the grove for the CV boot.

 

I will slide them right in this weekend and report back.

Edited November 15, 2014 by whatnow123

[RebekahsZ]

What tool did you use to cut the axle down? I have a portaband, angle grinder, and a miter saw with a fiber blade.

[whatnow123]

Hey Reb,

I did it with a hose clamp and an angle grinder.

[whatnow123]

So I installed my newly shortened CV axles yesterday. I installed the pass side first and then the drivers side. When I installed the drivers side, I had the control arm supported higher then when I did the pass side (I don't like the suspension to hang from the top hats).

Anyway, both popped right in without removing the strut and I had at least 1/2 inch of clearance. I then took her for a drive and it might be my imagination but it seems much smoother so drove on over to the freeway to test her out and no issues at all and it got rid of the slight vibration I used to have at 90+.  When I got home I pulled one of the axles (drivers side) to check to make sure the cage stayed put and it did. So, about 30 miles and so far so good. I will keep this post updated as I put more miles on my conversion.  I might add that my car is only lowered about an inch.

Edited November 16, 2014 by whatnow123

[RebekahsZ]

Looks great!  The last thing to do to verify your axle length, is to drop your spring seats on the threaded collars and jack your suspension up, using a jack under the spindle, to the lowest level you could imagine your car squatting to under hard acceleration.  (Remember, the axle needs to be as short as possible in order to install it when the suspension is in full droop/hanging from the top hats).  The axle needs to be as LONG as possible in order to not pull out of the outer CV (or out of the diff,depending on which c-clip is strongest) when the suspension is in full compression.  Back to where I started: so once you have your suspension compressed, pull back the larger diameter side of the outer CV boot and inspect to be sure the balls are riding in a position well inside the CV "cup".  If not, the axle will pull out of the CV some random time when you launch hard.  When the cage jumps out of the cup, it jams the inner CV into the diff.  I only know this by experience from having both axles that were too long and too short.  The outer CV cup is so short that there is actually a very narrow window between too long and too short.  That window is so narrow that I have to change one of my axles when I change my camber significantly when changing from drag set up to autocross/roadrace setup.  Instead of fancy CV band clamps, I use large screw-type hose clamps from the hardware store on my CV axles to make this sort of inspection easier.  So far they have never slipped-even when a CV came apart.  I'm gonna try your technique, but I gotta get some more axles to play with. 

[whatnow123]

Reb,

Maybe we have different CV axles, but the outer CV cup of my axles has about 2 1/2 inches of movement (<-- this is wrong, I forgot about the bearing cage, it's probably closer to 1 to 1 1/4 inches as stated below) within the cup (which is why I even considered this). I did pop off the outer cover to judge where the bearings were riding within the cup at installed length, and they were about in the middle of the CV cup, maybe a little towards the wheel.  I can't take a measurement right now since the axles are installed, but just from memory and looking at the above photos of the stock length axles and where the bearing rides; when it would bind from the axle being to long as you mentioned, I can see how the bearing could be on the outer edge of the cup and flipping the cage actually moves  where the bearing rides in the CV cup closer to that outer edge (the bearings are in the center of the outer cage, but sit on the first 1/3 of inner race which is secured to the axel), so I can understand how the bearing could bind up in such a situation. While I took off 5/8 of an inch on axle length, I only moved the bearing back on the axle maybe 1/2 an inch with the cages flipped. Given what you have described above about to long an axel (I'm assuming stock) and to short of one, the 1/2 inch I moved the bearing should be in the sweet spot of the CV Cup for movement.

Edited November 23, 2014 by whatnow123

[Domzs]

Interesting. Looking forward to your long term testing. Keep us updated.  . 

[JMortensen]

Should work fine, you lose some spline engagement where the old groove is so maybe a little weaker than Chequered Flag's aftermarket shafts. You don't have 2.5" of plunge on a Z31T CV. I want to say it's like 1.25" or something like that. Taking 5/8" off both sides should fix the issue with the stockers being too long though. 

 

You can cut an axle with just about anything and not mess up the temper of the axle. When I worked for Randy's R&P we used to sell full float axles for big ass dually trucks that had 8 or 9 inches of spline and were cut to fit by the customer. If you wanted to be cautious about the axles on any vehicle those would be the ones, but never heard any complaints at all.

[RebekahsZ]

Great (on the cutting), and I'm so glad you are making this so simple (I tend to over-complicate EVERYTHING).  Maybe in the future I can make a set of axles such that I don't have to swap one when I do camber changes.  With what tool did you cut the c-clip retention groove?  If I could build up a stack of ready-to-go axles and design and build an axle retention system to keep broken axles from destroying the contents of my inner fenders, I would think about some NO2 (I'm currently at the limit of my car's durability/reliability).  I'm really peeved because I sent a stack of long-side axle shafts to the salvage yard about 6 months ago! Do as I say (not as I do): don't throw anything away! 

[whatnow123]

Just a quick update on this. I've put about 350 miles or so since installing the CV's, mostly spirited driving .  About 240 miles of that was with a local Z club that went on a drive last weekend up in the AZ mountains. Pretty much a strait shot there and very twisty smooth road on the way back so I got to stretch her legs a bit. Anyway, about 35 miles from home I started to get a vibration above 50 mph and was thinking it was the CV's after I just beat on them (got up to about 130 at point). I pulled both CV's only to find the axles I modified had stayed put .

Turns out one of the C clips holding the u-joint cups in place on the drive shaft came loose and the bearing cup was backing out causing slop in the drive shaft. I guess it's best to always check others work! Cheap easy fix and was relieved it wasn't something more and it happened close-ish to home.

Anyway, so far so good on this MOD!

 

 

 

 

 

[puretone]

So I have a set of Z31 turbo CV axles that have been staring at me in the garage and I have recently ordered the MM CV companion flanges. I have been reading about what it takes to install them (flip the bearing cages) and I have also read they are just a touch to long and load the ring gear in the rearend. I have a rock solid r200 LDS and don't want to F- it up.

 

Anyway, I took the CV's into work to flip the cages and got to looking at it. The bearing cages are held onto the shaft by a couple of C clips at both ends and then slides within the CV housing. After flipping the cage, the axle itself is now the longest point. I got to thinking about this, it's the CV axle shaft that makes contact with the stub axle causing the binding which in turn pushes against the diff and can wreck the ring gear/carrier bearings. This is why MM sells shorter axles (by 1/2 inch I believe).

So I got to thinking, why not just move the channels where the C clip secures the bearing cages and cut down the remaining axle? There is plenty of spline left on the axle for the bearing cage, the new grove I cut in the axle is still larger than the factory indentation for the CV boot, so I didn't compromise strength at all, so I'm not sure why no one has done/thought of this.

 

With that said and considering CV axles are way cheaper than a R200 LSD, I busted out the grinder and shortened the axles by about 5/8 of an inch. I made 2 new groves for the C-clips and I believe I have a very inexpensive solution to buying shorter axles.

 

I just wanted to post this and to see if anyone can chime in to a potential problem that I'm not seeing as this seems like very simple and cheap solution..

 

I stole a couple of photos from another web site as I didn't take a photo of what just flipping the cages looks like.

 

One is as it sits, the other is when it is flipped... and then on from there.

 

LOL!

 

Focusing of a camera lens is not your strongest suit now, is it?

[DonH]

Found this thread - I’m calling BS on anyone that got a drivers side to fit with the cages flipped lol.... I’m doing these cutting measures later today on mine! Thanks for documenting - I’ll add to your thread even though it’s 6 years old. 

[mainboyd]

On 4/11/2020 at 10:13 AM, DonH said:

Found this thread - I’m calling BS on anyone that got a drivers side to fit with the cages flipped lol.... I’m doing these cutting measures later today on mine! Thanks for documenting - I’ll add to your thread even though it’s 6 years old. 

I literally just finished installing the CLSD and CV axles from the Z31 turbo into my 1972 240z this morning. All I did was flip both cages and grinding the extra threads sticking out of the stub axle after the nut. Everything seemed to fit just fine and this was when the suspension was just hanging from the top hats. 
 

I’m just wondering how do I know if there will be no binding? It rotates fine when the suspension is hanging. I am going to jack the suspension up as much as possible to then see if it will still rotate. But if there was binding then what are the symptoms? Will it not rotate? Or making a clunking sound?

 

I followed every step from here: 

 

 

 

[JMortensen]

You said you followed the info in the other thread exactly. The CV adapters in that thread are much thinner and I'm guessing all of the grinding the end of the axle stuff was unnecessary. The old Modern Motorsports CV adapters don't fit, which is why I made shorter axles for a while.  

Usually if it's too short you won't be able to put the CVs in easily. The old anecdotes were usually things like "I had to disconnect the strut at the top, install the CV, then force the strut back into place." 
 

[mainboyd]

The flanges I bought were from silvermine motors and I made them the same thickness as the flange from the CV axles. Which went from 12mm to 8mm. I figured if the Nissan engineers believed 8mm thick flange would be strong enough then why not the adapter flange…

 

I probably didn’t need to grind the little stub off but I did just for safe measure. 
 

I have pictures of the before and after machining the flange adapters and a side by side pic of them next to the flange end of the CV axle in my IG page @ideation_z if you want to get a better idea of how they look like. They look very similar to the post I said I followed. The only difference is that the silvermine motors adapter is completely round, which I don’t know why they weren’t made like that in the first place because that less machining which means cost less. 
 

Anyways, like I said, it seemed to fit just fine for me. Wasn’t too long or too short and I installed them while the suspension was hanging at its lowest. I haven’t dropped the car yet but I can follow up on this thread and confirm if there were any problems or not.