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More questions on CV axle conversion


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I am seriously considering converting my 240Z with 300zxt LSD and half shafts with u-joints to CV's. I have a set of CV axles from the 300zxt that I got the rear end from. Do they handle power better than u-joints or are they just safer than the u-joints as they can cause a very squirrelly episode at the track as I have personally experienced.

 

Mike

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Mike get the CV conversion done. I just cut a 1.63 60 at the track today. I broke my 411 R200 last week on a series of 1.6s. Im surprised the R200 went before the axles but they are much stronger than the U-Joints for sure. I switched back to a 3.54 rear today and cut a 1.63 and 11.99 at 112 so there wasnt much difference between the two except the MPH was a little higher. I posted my time slip on the Hybrid TIMES forum. Gotta love that 3500 EDGE convertor...

 

Terry

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Terry,

 

Did you just buy the adapters from Ross? I think they were like 220 bucks. Also did you install the 280Z stub axles as well? I have heard they are a bit stronger than the 240 stubs physically they seem to be the same size but I think they have 2 more splines on the 280's.

 

Thanks,

Mike

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Yes Sir, I got the adaptors from ROSS. I would suggest his product. No I still have the 240 stubs. I am gonna upgrade to the 280 forged stubs he is making later so I know they will last. There is so many choices. If you want to do this only once I would suggest saving enough money for the 4340 Billet steel adaptors and stubs. Then get a set of axles from Mikelly or Moser. I am running an open diff by the way so an LSD would be just fine I expect.

 

Terry

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Mike, also YOU ARE and I will be in the position to think about a straight axle in the future. You cant go to much quicker without long term headaches of the weak links etc...

 

Since Im following you, lead the way oh Master of Torque!

 

Terry

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Well, I peeked under the 280Z today and I can see how the sway bar will hit the CV boots when I convert to them. However, it looks like I can stay with the Suspension Tech (stock 280Z) sway bar I have by just putting in some very short endlinks. I hope thats all I need to do.

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I temporarily mounted the CV shafts and the swaybar end has about 1/4" of clearance to the largest part of the CV boot with the control arm fully down. I jacked up the control arm to the nornal compressed position and the clearance went to about 1". It looks like the ST rear swaybar on this car will clear the CV boot fine--I only tested the drivers side so far. I hope things don't change when both control arms are up.

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I'm still thinking about this, and I'm wondering why the endlink couldn't attach to a bracket welded to the control arm in a different spot. Obviously the end of the bar would be shorter which would stiffen the bar, but should work and be out of the way. Also I was looking at a control arm the other day and the oval area where the bar attaches ALREADY HAS 2 holes. Why not just cut 2 inches off the bar and attach to the rear hole instead of the front? The rear of the bar could be spaced off of the uprights and that would lessen the stiffening effect. Takes a little modification of the bar, but I think that's what I'm going to end up doing. Just cut the end off and weld a new end on kinda like Terry did, except I'm going to weld a tab with 3 holes to make it adjust. Anyone see any reason why not to do this?

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  • 2 weeks later...

OK Update. I installed the new R200 3:54 diff, installed my homemade CV adapters, and popped in the ZX Turbo drivers side CV shaft. I released the LCA inner bushings to allow the arm to swing out for room to insert the CV shaft.

 

I bolted it all up and with the LCA fully extended, the CV shaft is at an extreme offset angle and "lumps over" as I turn the hub by hand. When I jack up the control arm about 2" from fully extended, the CV shaft smooths out and seems fine all the rest of the way up. Is it normal for the CV shaft to "lump over" with the control arm at max. extension? I am wondering if I am binding the CV shaft (compressed too much in length to fit). My spacer is 1.25" thick and I cant see it being much thinner due to the bumped out center cone on the outboard end of the CV shaft.

 

As far as the swaybar clearance... With the LCA fully extended I have about 1/4" clearance from bar to boot. With the LCA in normal ride height, there is about 3/4" of clearance from bar to boot.

 

8779P4030109-med.jpg

8779P4030112-med.jpg

8779P4030108-med.jpg

(280Z with rear swaybar forward of the diff.)

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I'm about 99% sure that you are correct - you are binding the CV joint(s) and the issue is that the adapter is too thick, causing the tripod joint to bottom out in the reciever of the CV joints.

 

Any way you can make them thinner? Cut a pocket into the side shown where the compantion flange bolts to it?

 

Or just buck up for Ross's adapters, which are a proven solution.

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Yes, I can make them thinner on the lathe by either facing them or putting in counterbores. After all that machining, I am not going to throw in the towel. The only limit to the thickness of the spacer is the "cone" in the center of the CV shafts. The "cone" protrudes about 1" from the CV shaft mount face. There is no way to make the spacer much thinner than 1" or that "cone" will hit the stub axle end. Right now the spacer is 1.25" thick. Not to dis Ross but I would rather save the $$ for a future engine management system. I always try to fabricate what I can to save $$ to buy the items that I can't fabricate...Dollar stretching. We should all know about that; we drive hybridZ's.

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I understand the desire to DIY it.

 

I think if you can get it down to around 1", it will work without binding. But if you can do it by creating a pocket for the companion flange bolting rectangle, that would help a good bit.

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You've got to be very close or the assmebly wouldn't turn over at all. I'd recess the adapter as much as possible. On another note, what exactly is that protrusion on the joint for anyhow? Could it be machined or cut off? If it serves to keep the CV joint located mechanically (and the bolts just keep things together) then a recessed outer lip in the adapter would do the same thing. That is how my diff side flanges are made and the CV joint is flush across the face.

 

What a minute, if you've got the LCA dropped to it's max extension then isn't the CV axle also fully extended? If that's the case then maybe the shaft is too short? Or maybe you need to reorient the cage to gain back the 3/8" length (assuming you've done this minor mod as recommended by Ross)? On my old land rover I used retention straps to prevent the rearend from dropping out to much and pulling the driveshaft apart while offroading. That might be an option. Lastly, is there any chance of the LCA actually being in it's extreme droop under any condition but a bodyjack?

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The CV shafts are from an 80-83 ZX. I don't think they require disassembly and reconfiguration normally as long as they are not bound up or overly extended.

 

In my case, I had to compress the CV shaft nearly to it's shortest range to get it to fit. Like I said originally, with the control arm fully down, there is a pretty severe angle on the CV joints. When I turn it by hand in that position, it "lumps" as the lobes turn. As soon as I lift the LCA a little bit, the shaft straightens out and it turns smoothly. With the LCA jacked up horizontal, it still turns smoothly. I still think I need to remove about 1/4" from the spacers but that is just a hunch on a rough measurment.

 

The "cone" protrusion on the end of the CV shafts is....?? I don't know. I can't believe my curiosity let me off the hook that easily. Usually I tear things apart because I can. I will look into it tonight...but I assumed it was there for a good reason and that it needs to be there...you know what happens when you assume.

 

If and when I do machine another 1/4" off the adapter, I will probably put 1/8" deep pockets on both sides for centering the mount-up. I will revise the prints and post them.

 

-darn, they just raised my property tax AGAIN!

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I took my adapters that were 1.25" thick and machined them down to 1.1" thick. It was easier to put the shafts in place and they turn smoothly with the LCA fully up or fully extended. I will test drive this weekend. The downloads section has the updated print for the CV adapters that I made.

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Just want to post an update on the 280ZX CV axle conversion on my 76 280Z. I shortened the sway bar end links so that the distance between the middle bushings is about 1". This gave me a little more clearance on the end of the sway bar as a safety margin. I also noticed that the inner CV was very close to contacting the top of the control arm on the passengers side. I removed the mustache bar top washers ( I have the urethene bushings) raising the rear of the differential about 1/4". This gave me a more comfortable clearance. It runs smooth and quiet under power and under decel....over and out.

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I'll throw a point in here as well. One advantage of having the CV shafts compressed almost to their limit is that the tripod thrust bearings are now located more deeply within the "tulip," which is a stronger location that being spaced further outboard. In addition, if any wear has taken place from previous usage, the newer, more compressed location will locate these thrust bearing into an unused protion of the tulip, which more often than not, will remove any slack you may have had before.

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