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1974 260Z 300ZXT CV Axle Conversion


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Hello all. I am looking for a R200 CV axle swap guru to help me out.

 

I recently decided to go r200 in my rb25 260z and along with that, I purchased silverminemotors CV axle conversion weld on plates for the stub axles and had two CV shafts mailed to me as well (driver and passenger)

 

These axles are the 4 bolt turbo units.

I welded on the flanges and installed the r200 along with all the proper r200 swap suspension components. After install, i tried to mate the cv's to the stub shaft flanges after fully inserting the splined side into the r200. Unfortunately, they are too long and do not slip behind the stub shaft to bolt in. When i say too long, i mean by millimeters. I can unbolt the strut, bolt the axle on, and then force the strut back into place. This then puts so much outward pressure caused by the CV on the hub that you cannot adjust the coilovers. Not to mention, the axles are fully bottomed and this will cause a great shock load to my differential carrier bearings and axles. 

 

The way i see it, i only have one option and that is to get these axles shortened or have custom axles made.

 

To whom it may concern, the r200 is a 86' 300zx 3.7 welded unit. The differential cover, mustache bar, cross member, and front mount are all off of a 280z with an r200 as well.

 

I have spent days researching this topic and it seems as if nobody ever has this problem. Obviously people flip the cages to accommodate for an extra 3.5mm which almost eliminates any binding problems on suspension jounce. Unfortunately these are aftermarket CV axles that have a tripod joint so I do not have the option to flip the cages. Even if i saved that 3.5mm, i would still have binding issues.

 

Any help would be greatly appreciated. At this point, i think I am just going to have these axles shortened and hope they last. I am just trying to pick anybodies brain who has had this issue before i throw money at questionable tripod units.

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  • 1 month later...

Hey Zach, I have the exact same issue you have other than my shocks are factory. Still working on the restoration and haven’t driven the car. I agree something isnt right. During the install it was pushing the tripod caps off the axles. Silvermine said they use the same brand cv axle. 1984 300zx turbo correct? Did you find a solution? Thanks...John

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  • 3 weeks later...

There are several ways to gain some clearance.

 

First, you can install adjustable bushing in the rear control arms and adjust them for maximum negative camber.  This moves the strut outboard and gives you more clearance. The problem is that this may give you more negative camber than you want.  If you have rear camber plates then you could move the top of the strut outboard as well to tweak the rear camber and gain more axle clearance.

 

Second, you can lower the differential.  The axles are shortest when they are in a straight line from the differential to the wheel.  If the differential is low enough, then the stub axle at the wheel will always be above the shaft coming out of the differential.  This works for low vehicles with limited strut travel, and is what I have done.  I use bushings above the mustache bar to lower the rear, and adjust the angle at the R/T mount at the front of the differential.

 

Third, in theory you could shift the differential forward or aft to gain clearance (same concept as lowering the differential).  The axles would always be angled as seen from above, but the CV joints can handle that.

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I made shorter CV shafts for this purpose. Stopped making them maybe 10 years ago, but gave the technical drawings to www.modern-motorsports.com and Joe over there still makes them. http://www.modern-motorsports.com/z31-half-shafts.html

On my own car I made custom LCAs that were 1/2" longer than stock (did this before I made the shafts).

 

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  • 1 month later...
On 7/16/2020 at 10:28 AM, JMortensen said:

I made shorter CV shafts for this purpose. Stopped making them maybe 10 years ago, but gave the technical drawings to www.modern-motorsports.com and Joe over there still makes them. http://www.modern-motorsports.com/z31-half-shafts.html

On my own car I made custom LCAs that were 1/2" longer than stock (did this before I made the shafts).

 

I had a similar issue with doing this CV conversion.  I actually bought the companion flanges from Ross at Modern Motorsports years ago, and found a set of 300ZXt axles.  Never got to the project until about two months ago.  At the time when I purchased the companion flanges, It was  my understanding that all you had to do was flip the outer cage on the axles and you were good to go.  I had the same fitment issue, even with the cages flipped.  I contacted Joe, who now runs Modern Motorsports, and he said that he did NOT have the axles, and was not getting any more, and he also told me that he did not have the specs.  Hmmm.

          As it turns out, I WAS able to find a set of axles from Whitehead Performance.  They are roughly an inch shorter than the stock units.  Not cheap, but this will be a proper conversion with excellent fitment.

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