Birfield CV 27-Spline versus 30-Spline Aftermarket

[KevinMLee]

I couldn't find any info on this on 'Mud or Here. All the info I have is people saying they have 30-Spline Birfields on their rig.

Here's what my situation calls for. I have to do the famous 80-series Front Axle Knuckle rebuild and I'm fine with that. I'm already putting in all new bearings and so forth. So I figure, it might be a good time to replace my Birfield CVs and Axles to new stronger Chromoly. While I know I don't have to replace them for my current driving, I would like to replace them for piece of mind now than have to stress about it on a trail. I don't do a lot (if any) crawling because my rig is setup for trails and overlanding, not crwling.

What I do know, is that the Stock OEM Birfield CVs are 30/27-Spline which causes problems at the 27-Spline end of the axle/joint. And I do know that the 30/30 is a much better setup and is much stronger.

So here is my quesion, If I do upgrade to the 30/30-Spline... are there additional parts I need in order for this to work? meaning, do I need a new hub also, do the bearings need upgrades, etc? Or are the 30/30-Spline Axle/CV all pretty much "drop in"? Also, are the 30/27-Spline Chromoly upgrades a "drop in" part?

Truck is a 1996 LC FZJ80.... everything in relation to this thread is Stock OEM.

I'm looking at both the Longfield and the Nitro Axle/CVs.

Thanks guys for all your future help.

 

[cruiseroutfit]

All you would need beyond the normal knuckle overhaul parts would be the axle combo set and some of the axle clips. Fwiw the typical 80 Series break has nothing to do with the 27 splines but rather the bell (shell of the birf). Upgrade the 27 spline birf to Chromoly and it is as strong as the 30 spline bell. Now, upgrade the actual birf and the inner axle (which is 27 spline stock) becomes the next weak link and thus the 30 spline is an upgrade above and beyond the chromo 27 spline birf. Keep in mind while 'clicky' birfs will be solved by replacing the birf set, it won't prevent that from happening in the future and in some cases, chromo birfs will click much sooner than the stock units so it isn't always the ideal option. However if strength and durability are your #1 concern, I'd recommend you do the chromo options, which of them comes down to your budget and personal needs.

While a new combo (inners/outers) set is more expensive, it also leaves you with a full set of spares in the event you did have a failure. If you do the chromo 27 spline outers (birf) you may break an inner or you may break the birf, you could possible re-install your stock birfs but it can damage the splines on the inner and be a difficult trail repair. Hope that helps.

 

[KevinMLee]

Thanks... I think I grasped most of what you've said already and much of it makes perfect sense reiterated. So if I decided to do the 30/30 (meaning inner axle and the birf), then I would have to upgrade the hub at all to accomodate 30-splines as opposed to the stock 27-spline?

thanks for the help again!

 

[cruiseroutfit]

Thanks... I think I grasped most of what you've said already and much of it makes perfect sense reiterated. So if I decided to do the 30/30 (meaning inner axle and the birf), then I would have to upgrade the hub at all to accomodate 30-splines as opposed to the stock 27-spline?

thanks for the help again!

Negative, it isn't those splines that go from 27 spl to 30 spline, rather those inside of the birf that get upgraded. This allows the axle shaft to stay a consistent larger diameter rather then 'necking' up for the axle seal surface and then tapering back down at the birf which is where they would start to fail. 91-94 FJ/FZJ80's will have to run the later model 95+ outer drive flanges because they length of the birf changed and aftermarket axle manufactures build the HD shafts for the later flange as it is a better design. Feel free to give us a ring at the shop if you have any further questions, we deal with Nitro as well as all the additional knuckle parts you will need for the swap/upgrade/rebuild/