Different types of Z31 turbo axles

[RebekahsZ]

I'm working on my R200 conversion and wanted to show some different Z31 axle configurations for comparison and discussion.

 

The shortest (and cleanest) axles are rebuilt and modified with JMortensen's shortened shafts for installation into S30; I have also flipped the outer CV cages to shorten an additional 1/8". The longest (and rustiest) axles are from a 1988 Shiro model Z31 with VLSD. The middle set is stock Z31 turbo. I was not expecting the Shiro VLSD axles to be so significantly different from the standard Z31 turbo axle - the inner CVs with their splined output shafts are entirely different.

Edited May 2, 2012 by RebekahsZ

[tamo3]

Interesting.

Is the width of Siro pumpkin and other Z31 Turbo different?

[JMortensen]

The splines have to engage the VLSD part of the diff, so they're longer.

[RebekahsZ]

The Siro (Shiro?) axles I have are super rusty (from Ohio) on the inner and outer CVs, The regular Z31 turbo axle inner CVs are shiny under the paint, almost as if they are machined stainless steel. Is that true? Are the inner CVs stainless? I'm gonna have to get the Siro CVs sand blasted and I'm probably going to wind up swapping the Siro VLSD carrier into another differential case - rust is coming off of the casting in great big flakes.

[JMortensen]

I don't think so.

[RebekahsZ]

Ok. I will put a little paint on that shiny metal instead of polishing it off.

[z240]

Ok, I'll ask the question. Are the VLSD CV's candidates for the shorter shafts that Jon makes? Anyone had a set apart to check?

 

Reason I ask is, a local member has recently acquired a nice VLSD and shafts for his 76 280, but judging by the CV shaft lengths I see here compared to the other, ain't NO WAY they are going to fit in the dang car without Jon's short axles....

[RebekahsZ]

I have ordered a set on johns next batch. I plan to build it up and let folks know. I think lots of length will be consumed inside the l s d.

[SUNNY Z]

Now you have me re-thinking my Q45 swap. What are you planning on doing as far as a pumpkin goes? Longnose R200 with a LSD?

Edited May 3, 2012 by SUNNY Z

[RebekahsZ]

SUNNY: Don't change your mind - you have all the parts already and got them cheaper than I did. Stay the course! I don't know why, but the Q45 R200 diff has a much better reputation than the standard R200 (I've never held one in my hand to know the differences). You are a way-better fabricator than I am - whatever you put together will be top notch. Plus, this way we can compare notes. I think with bolt-on axles without any snap rings to overpower while under the car, your Q45 axles will be a little easier to deal with. I will still have to wedge my inner CVs out to remove my axles and I anticipate a little cussing under the car when doing that. With outer CVs on each end of the Q45 axle you will also be able to feel for available end to end travel/bind.

 

When I get my Wolf Creek axles off the car, I will post some pics of them too. They use a totally different type of CV joint. On the Wolf Creek, the length adjustment (thru range of travel) is in the axle splines, whereas in the Z31 CVs, the length adjustment occurs in the outer CV joint as the CV balls move in the grooves in the CV housing. It is pretty interesting stuff. One cool thing about the Wolf Creek, is that you can actually reach up and feel how much travel you have left with your hand. Because there is no "wiggle" in the Z31 inner CV, it is much harder to know if you have any travel (slop) left in the system. You have to make that determination before you bolt them in. The trade off I see between the Wolf Creek is this: when rebuilding the Z31 axles you have these snap rings to deal with that are a real PITA, whereas with the Wolf Creeks you have none of those snap rings, but 20 bolts per axle to tighten, trust and inspect and 12 to safety wire. Greasing and prep-ing is easier on the Wolf Creek, but I think on-car installation and subsequent maintenance is going to be easier with the Z31. As far as durability, I've spoken with folks who have broken both and I've talked to guys who have gotten years of faithful service from both. But those comments/comparisons also apply to stock u-jointed axles too! Headed to garage now to finish the pumpkin up.

[JMortensen]

The splined part of the CV plugs into the diff as Keith suggests. I don't know if the CV shaft itself is longer on the VLSD, I would assume that they're exactly the same as the regular turbo shaft, I'm hoping Keith can answer that once and for all. Wolf Creek uses a 930 Porsche CV joint. It's a very common CV that lots of different cars use because they are strong and cheap. It's like the SBC of CV joints. You're right that it has "plunging" joints on both ends, and when you put power to it it self centers because of the design of the races. I've dealt with Todd several times and think he's a good guy and the product is nicely made from what I've seen in pictures. The center shafts for 930s are easy to come by because just about every dune buggy uses them along with a ton of different race cars, so you can get shafts in any length you want and it's much easier than say, having Z31T shafts machined onesy twosy.

 

If you're comparing the two options, I think it is safe to say that the 930 joints themselves are stronger. They have bigger ball bearings in them. That said, they're bolting to stock companion flanges which are undoubtedly weaker than chromoly parts from M2 or Chequered Flag or MM, and the adapter part is aluminum if I understand correctly. The flange on the stock companion flange is sized for a U-jointed halfshaft and is absolutely tiny and frail looking compared to the CV adapters. The chromoly adapters are at least twice as thick and have a nicely radiused curve towards the much larger flange. If there is going to be a meaningful strength difference, this is where it's at, I think. I think the safety wire suggestion is a good one. I do believe that Keith is right that the M2 / MM / Chequered Flag setup is going to be more bolt on and forget it, and on the other you'll need to constantly be checking bolts (or safety wiring them). Failures of either CV are pretty rare, and I do wonder if the incorrect length of the CV shaft might be a contributing factor in the Z31T shafts. I remember one guy here broke the cage inside the CV shaft. Failures of the CV's is not a common problem, regardless, but that particular failure seems to me like something that might happen when the CV bottoms hard. That's just speculation though. The way you check travel on the Z31 joint is by unbolting the inner CV and moving it all the way in as though you were going to take the CV shaft off. If you move it 1/16", you have very little compression travel available in the joint. If it moves 3/4", you're pretty close to dead center.

 

I don't know anything about the shortnose shaft CV swap. Whatever info I had available at the time was put into my diff post, but I'm sure there are other more detailed suggestions as to how to make that happen. I'm not a huge fan of the shortnose swap because it's a pain to do. You go through all the mounts and all that and you end up with an LSD that just isn't as aggressive. Depending on what it's used for it may be fine, but when I look at it I see minimal weight savings, lots of efforts, and a relatively weak LSD.

 

You still having trouble with those snap rings Keith? This is confusing me: "I think with bolt-on axles without any snap rings to overpower while under the car, your Q45 axles will be a little easier to deal with." If that wasn't a typo and you're actually trying to get that circlip in under the car, then there's your problem. You should assemble the CV shaft on a bench and then put the assembled shaft into the car. No need to mess with all that on your back.

Edited May 5, 2012 by JMortensen

[RebekahsZ]

I've got the axles totally rebuilt off the car using a vice and getting help from my daughter. JMortensen, we are on the same basic sheet of music. In the axle rebuild, the main problem was my lacking the confidence to strike as hard as necessary with a 3 pound sledge. Once I committed to that it wasn't a big problem. I just fought and fought with inadequate hammer force because my dad was a rocket scientist and I'm an eye surgeon. The concept of pounding something into submission is just difficult for me to face up to. Once committed to the amount of force required, it was a breeze, just like you said it would be. I put my daughter on a stool and had her do the hammering while I massaged the c-clip and kept constant pressure on the shaft. My neighbors were probably spreading rumors after hearing me yelling: "Hit it harder, sweet-heart! Harder! Harder!" People always assume the worst in Alabama. It was a little scary with her swinging a 3 pound sledge right over my head-I'm surprised she didn't take advantage of the opportunity to give me a little attitude adjustment.

 

I and others have had some trouble getting the (already assembled) inner CV end of the axle to pop in and out of the diff, once the diff is installed in the car. That is what I'm referring to. I'm sure that too, is just a matter of me being a sissy. And the lack of a chassis lift doing this on my back. I'm getting a pretty good cussing vocabulary, which always helps just about everything. It is almost 1200-noon, I need a beer just thinking about it.

 

When you discuss checking for CV axle bind, I think you mean to unbolt the OUTER CV (typo?). You can't unbolt the inner CV; it has no bolts.

[JMortensen]

When you discuss checking for CV axle bind, I think you mean to unbolt the OUTER CV (typo?). You can't unbolt the inner CV; it has no bolts.

Thanks. Yes, that is a typo.

[zgeezer]

I've got the axles totally rebuilt off the car using a vice and getting help from my daughter. JMortensen, we are on the same basic sheet of music. In the axle rebuild, the main problem was my lacking the confidence to strike as hard as necessary with a 3 pound sledge. Once I committed to that it wasn't a big problem. I just fought and fought with inadequate hammer force because my dad was a rocket scientist and I'm an eye surgeon. The concept of pounding something into submission is just difficult for me to face up to. Once committed to the amount of force required, it was a breeze, just like you said it would be. I put my daughter on a stool and had her do the hammering while I massaged the c-clip and kept constant pressure on the shaft. My neighbors were probably spreading rumors after hearing me yelling: "Hit it harder, sweet-heart! Harder! Harder!" People always assume the worst in Alabama. It was a little scary with her swinging a 3 pound sledge right over my head-I'm surprised she didn't take advantage of the opportunity to give me a little attitude adjustment.

 

I and others have had some trouble getting the (already assembled) inner CV end of the axle to pop in and out of the diff, once the diff is installed in the . That is what I'm referring to. I'm sure that too, is just a matter of me being a sissy. And the lack of a chassis lift doing this on my back. I'm getting a pretty good cussing vocabulary, which always helps just about everything. It is almost 1200-noon, I need a beer just thinking about it.

I use a large cold chisle and a middle weight hammer. The chisel is used as a tapered ramp...not to cut. Lay the flat of the chisel 90 degrees to the cv axle on the differential and slide the point/cutting edge of the chisel under the cv joint dust shield and tap it. Move the chisel around to apply pressure at different points on the circumference of the joint. Easier while laying under the car than using a screwdriver as a lever.

 

g

When you discuss checking for CV axle bind, I think you mean to unbolt the OUTER CV (typo?). You can't unbolt the inner CV; it has no bolts.

 

 

 

[RebekahsZ]

Thanks zgeezer. I've got pictures of that very same technique posted on another thread. It is the only way I can get them out.

 

OK. I just broke a stack of drill bits trying to drill the grade-8 axle bolts for safety wire. I tried 2 different types of safety wire drilling fixtures. Tried hardened bits and lots of oil and a drill press. That aint happening. Looks like its gonna be red lock tite for me! Then maybe some aviation torque seal for visual inspections.

Edited May 6, 2012 by RebekahsZ

[SUNNY Z]

So is there a possibility of the Z31 T axles that Jmortensen sells fit in a Q45 CV shaft? Can anyone give the specs on the two axles? I've read somewhere that the Q45 axles are 12" per side, but I don't know the spline count or diameter or where the c clips are or any of that business. However, I think IF i could get the specs on the q45 axles, I could just call up Moser, and get a set made. I'm going to try them later today if I remember. I'd like to get this little project done so i can DRIVE my car instead of baby it everywhere....

[JMortensen]

If you're looking for shortnose CV shafts, I think Ross already has that covered. If you wanted to try to use the 88SS VLSD shafts with my short CV shafts and Z31T adapters, I'm betting that would also work, but can't say for sure.

 

I can tell you that I'm not going to make the shortnose CV shafts, unless something changes.

[RebekahsZ]

I feel confident that JMortensen's shortened shafts will not work with the Q45 swap. With the Q45 swap, you use an outside CV on each end, so the snap rings are different. Those Q45 swap axles that MM makes are really short when compared to the Z31 axles. I'm confident that you can't mix and match the combo.

 

It will be a while before I can confirm that the Shiro axle shafts are the same as the Z31 axle shafts. I will want to actually try it out to ensure that the splines and everything are compatable before I put out info that is not correct. So, I'll be waiting for two things before I can start into that: a set of shafts from JMortensen, and time to get it done, competing with gettin my R200 swap done.

[SUNNY Z]

After a quick chat with Jon, I think I too am going to go with the Z31T differential. Although I've already sourced the Q45, I think that it would be more cost effective, and also just plain easier to do a z31.

 

I didn't realize the z31 was a longnose diff. Thats great, because that saves me getting a new driveshaft, and front mount, and cuts time off the swap.

Edited May 7, 2012 by SUNNY Z

[RebekahsZ]

There is a forum thread sticky about Ross at Modern Motorsports that you should read. He's just unpredictable. One minute, he's great and ships promptly; the next time he can't be contacted. Rumor is he's getting divorced. I feel bad for him - he has great products, but one of the reasons I did the R200 swap instead of a Q45 swap was this very issue. Don't bother getting frustrated with him: it is just a case of knowing the threat. You might get lucky, or you might get really frustrated - you just never know. Maybe somebody else on the forum will have a secret phone number for him?? I assume you tried email?

Edited May 7, 2012 by RebekahsZ