CV Axle Discussion Thread

[theesotericone]

This will be a place to dream the ultimate IFS dream. That dream is bullet proof CV axles. Well, I just talked to RCV Performance today. They already make CV's for 4th and 5th gen runners and 2nd and 3rd Gen Tacos.

As most of you that wheel an IFS rig know stock CV's break. A lot. We've all gotten very good at swapping them out. I've done 5 this year. This got me thinking about after market options that are stronger then stock. One very well known company for 3rd gen runners is Lotus.

Lotus has re-designed and strengthened the outer tulip. They have left the inner tulip untouched. A set of there axles will run you $1200 bucks. They carry a one year warranty.

The problem I've always had with Lotus is the fact the inner joint is still stock. I have broken inners as have most of the guys I wheel with. That has steered me away from them and left me just replacing NAPA axles when I break them.

RCV is pretty much the heavyweight when it comes to CV axles. They are bomber. So bomber if fact all of there CV's carry a lifetime no questioned asked warranty. If you break one they replace it. You won't break one though. Cost will be in the neighborhood of $2000.

The whole axle is redesigned. Here's a small snippet about the architecture from RCV's site:

The axles feature a double-offset inboard CV joint that is comprised by 1-inch balls and 300M internal components. The outboard CVs utilize our Dana 60 architecture with combination of 4340 & 300M components optimized for maximum strength. The center bar is 35 spline 300M, the strongest in the industry. The RCV developed moly is used in the CVs to control heat build-up in even the most extreme use environments.

I've been waiting for RCV to get the 3rd Gen runner CV's to market. After I call with them today I was informed it's a go. They expect to have them available in a few weeks at most. So this leads to some discussion about having bomb proof CV's.

The logical question is what's the next weak link in the front drive train?

That also leads to the question of how much weaker are stock CV's then the rest of the drive train?

Is it possible to upgrade CV's and not have other things breaking instead of the CV's?

For a long time I was one of the guys saying to leave the stock CV's and just replace them. They are the weak link and they are easy to pull and replace. I'm reconsidering that position. I'm curious to hear others thoughts about it.

What do you guys think?

 

[4runner DOA]

I'd be worried about the front gears, but I don't know how strong they are. It comes into the question of why they're breaking to begin with. Bad angles at droop or stuff? Spinning to traction while locked? Mine both snapped while locked and spinning with no traction.

 

[Hold My Beer & Watch This]

I am SFA, so take it for what it is. My setup is RCV's with ARB, and RCV hub gears. The weak link, from first hand experience, is the R&P.

If you wheel your truck with respect instead of like a disposable toy as I do, then you should he fine. I fucked up and took the RVC rep up on his challenge when he dared me to break his axles and he will replace them on the spot.

 

[AssBurns]

Most of us have seen @dirtco’s ADD stub shaft picture when he sheared the stub shaft. There have been a couple others that have done the same thing. He was running Lotus axles then this happened. So I’d think that is the next week link.
So there is the idea of Cryo or Boron treatment of the stub shaft. Idk if that would make much of a difference in overall strength though. So maybe we can get someone to make a 4340 or 300M stub shaft? That could be something to consider if it isn’t outrageous cost. Then there is the output shaft or the ADD collar that could be the next weak link in the ADD system. Are they going to be the weak link when it comes to the front diff though? What will be weaker? Diff or output shaft and collar?

So then we have to think about the front diff. All the front 7.5” front diff failures I’ve seen were the spider gears. Not saying they haven’t happened to the R&P but I haven’t seen it. I’m assuming that is because the CV’s are the weak link we’ll before the ring and pinion fails. We both have ARB’s up front so broken spider gears are quite a bit less of a concern. How much can the front R&P really take? I have no idea...

Dirtco’s broken ADD stub shafts



Diagram of front diff and ADD system.
#7 is ADD stub shaft
#5 is the ADD collar
#4 is the ADD output shaft

 

[theesotericone]

What will be weaker? Diff or output shaft and collar?

How much can the front R&P really take? I have no idea...

Pretty much. How much can the front components take? We both have Nitro gears and those are some of the strongest in the industry. I'm not really worried about the R&P. I guess we'll find out. I just gotta wait till my Xmas bonus comes in. Or not. lol

 

[AssBurns]

Pretty much. How much can the front components take? We both have Nitro gears and those are some of the strongest in the industry. I'm not really worried about the R&P. I guess we'll find out. I just gotta wait till my Xmas bonus comes in. Or not. lol

I need to get @4Running Daily to finish his LT kit so I don’t have to make one myself. His design is basically exactly what I had in mind, so might as well just use his kit. (If he ups the lower bolt size ). Then I can consider RCV’s. Which I’d definitely consider!

 

[4Running Daily]

I need to get @4Running Daily to finish his LT kit so I don’t have to make one myself. His design is basically exactly what I had in mind, so might as well just use his kit. (If he ups the lower bolt size ). Then I can consider RCV’s. Which I’d definitely consider!

New design takes that load off the bolt . Should be a lot better than before

 

[AssBurns]

New design takes that load off the bolt . Should be a lot better than before

When do I get to see it?

 

[4runner DOA]

When do I get to see it?

When he makes a new thread for it.

 

[RPS1030]

Most of us have seen @dirtco’s ADD stub shaft picture when he sheared the stub shaft. There have been a couple others that have done the same thing. He was running Lotus axles then this happened. So I’d think that is the next week link.
So there is the idea of Cryo or Boron treatment of the stub shaft. Idk if that would make much of a difference in overall strength though. So maybe we can get someone to make a 4340 or 300M stub shaft? That could be something to consider if it isn’t outrageous cost. Then there is the output shaft or the ADD collar that could be the next weak link in the ADD system. Are they going to be the weak link when it comes to the front diff though? What will be weaker? Diff or output shaft and collar?

So then we have to think about the front diff. All the front 7.5” front diff failures I’ve seen were the spider gears. Not saying they haven’t happened to the R&P but I haven’t seen it. I’m assuming that is because the CV’s are the weak link we’ll before the ring and pinion fails. We both have ARB’s up front so broken spider gears are quite a bit less of a concern. How much can the front R&P really take? I have no idea...

Dirtco’s broken ADD stub shafts

View attachment 924

Diagram of front diff and ADD system.
#7 is ADD stub shaft
#5 is the ADD collar
#4 is the ADD output shaft

View attachment 925

Thoughts on a stronger stub shaft that eliminates ADD?

 

[AssBurns]

Thoughts on a stronger stub shaft that eliminates ADD?

You’d want to go with manual hubs at that point to avoid spinning the whole front drivetrain. The Tacoma manual hub CV’s are weaker than ADD CV’s, but with 300M RCV shafts, that’s kind of a moot point.
I wonder if the manual hub guys ever had an issue with the manual hub output shaft that takes place of the ADD tube?

 

[Theblackflag]

MJke76Hl by Phoenix Black, on Flickr

Heres another twisted stub shaft... This was on @bigfishallday's rig that's only on 33s with a front locker. Personally, I don't see manual hubs fixing this issue since they still engage to the diff with the same amount of splines. The shaft that interfaces really are the next weak link after the outer CV cage and unfortunately there hasn't been a heavier duty solution made yet. I'm sure most here have followed @dirtcos build and know he's responsible for 3 or 4 of the 5 documented lotus axle failures and all of the failures were in the outer cage. Everything from breaking the cage to fracturing the center star.

The diff itself though I feel like for these trucks is plenty strong once you add an arb locker or auto locker of some sort. The spider gears are like glass, speaking from experience here...
IMAG0011 by Phoenix Black, on Flickr

When I replaced my front diff last winter I took the time to model my spare ADD stub shaft out and started looking at getting one produced from 4340 or 300m material. But it wasn't going to be cost effective at all. The billet alone to make the part was over 100 dollars and then the machining process was the next challenge. There's a lot of things to be done to make the little stub and every machine shop I talked except one that I have worked at in the past didnt want to touch it unless there was some sort of a volume order. The other issue is the small needle bearing inside the shaft, it proved difficult to source because of the odd sizing. So final cost was looking to be in the 6 to 700 dollar range which to me didn't really seem worth it since the ADD engagement collar and the outer shaft was still left stock and I can only imagine those would be the next failure point.

What it comes down to is horsepower and torque will always find weak links, the question is how much are you willing to pay and how far are you willing to chase that weak link.

 

[AssBurns]

MJke76Hl by Phoenix Black, on Flickr

Heres another twisted stub shaft... This was on @bigfishallday's rig that's only on 33s with a front locker. Personally, I don't see manual hubs fixing this issue since they still engage to the diff with the same amount of splines. The shaft that interfaces really are the next weak link after the outer CV cage and unfortunately there hasn't been a heavier duty solution made yet. I'm sure most here have followed @dirtcos build and know he's responsible for 3 or 4 of the 5 documented lotus axle failures and all of the failures were in the outer cage. Everything from breaking the cage to fracturing the center star.

The diff itself though I feel like for these trucks is plenty strong once you add an arb locker or auto locker of some sort. The spider gears are like glass, speaking from experience here...
IMAG0011 by Phoenix Black, on Flickr

When I replaced my front diff last winter I took the time to model my spare ADD stub shaft out and started looking at getting one produced from 4340 or 300m material. But it wasn't going to be cost effective at all. The billet alone to make the part was over 100 dollars and then the machining process was the next challenge. There's a lot of things to be done to make the little stub and every machine shop I talked except one that I have worked at in the past didnt want to touch it unless there was some sort of a volume order. The other issue is the small needle bearing inside the shaft, it proved difficult to source because of the odd sizing. So final cost was looking to be in the 6 to 700 dollar range which to me didn't really seem worth it since the ADD engagement collar and the outer shaft was still left stock and I can only imagine those would be the next failure point.

What it comes down to is horsepower and torque will always find weak links, the question is how much are you willing to pay and how far are you willing to chase that weak link.

Great post! I totally agree with that last part. There is always going to be a weak link that we will eventually find. Even if we ditched the ADD tube with a manual tube, I wouldn’t be surprised if the output/stub shaft is the weak link, because like you said, they engage the same way. I wonder if a manual hub shaft would be easier to make out of 300m since there isn’t a needle bearing to deal with like the ADD shaft. Then we have to think about the ring and pinion itself. I doubt it can really handle much more than what we have been throwing at it already. Did Dirtco ever have any R&P failures?

Is it worth polishing a turd, or would it be worth more time to do a whole IFS axle swap like we discussed in another thread.

 

[Theblackflag]

Great post! I totally agree with that last part. There is always going to be a weak link that we will eventually find. Even if we ditched the ADD tube with a manual tube, I wouldn’t be surprised if the output/stub shaft is the weak link, because like you said, they engage the same way. I wonder if a manual hub shaft would be easier to make out of 300m since there isn’t a needle bearing to deal with like the ADD shaft. Then we have to think about the ring and pinion itself. I doubt it can really handle much more than what we have been throwing at it already. Did Dirtco ever have any R&P failures?

Is it worth polishing a turd, or would it be worth more time to do a whole IFS axle swap like we discussed in another thread.

To my knowledge he never had a front r&p failure, just one in the rear over 5 years. Personally I feel like the front end is capable of supporting 35s reliably. It just takes a careful wheeler and the willingess to replace parts on a fairly regularly basis. The biggest thing is being very picky about your front locker engagement

 

[theesotericone]

What it comes down to is horsepower and torque will always find weak links, the question is how much are you willing to pay and how far are you willing to chase that weak link.

Exactly. To have a truly bullet proof stockish front end you have to go down a very deep rabbit hole. How deep it goes is what I'll probably find out.

To me it really boils down to can the other components take the torque my rig delivers. Once I end up with RCV shafts what answer should prove itself one way or the other. Maybe the rabbit holes not as deep as I think. Or maybe it's deeper.

 

[snotaco]

This is amazing to hear that RCV is finally coming into the game, me and a friend have been asking them for awhile when they were going to with them just saying it was in the testing phase.

We both have double cab, 5 speeds, duals, front arb, superchargers and 37s. I have manual hubs where he has add. I'm on my second front diff from spider gear failure (common) and nothing since going arb in the front and welding on bigger steering stops. He's broke one stub shaft (which it looks like everyone has agreed would be the next weak point) and the either broke a couple ring gear bolts or had them back out taking out all of it. Which leads me to my point, i think the ring gear would be the next weak point, or for manual hub guys maybe the hub itself.

True, being careful on the throttle and being fruitful with the front locker is the key, but where is the fun in that?? I do most of my wheeling in the snow and sometimes you need all of it

 

[AssBurns]

This is amazing to hear that RCV is finally coming into the game, me and a friend have been asking them for awhile when they were going to with them just saying it was in the testing phase.

We both have double cab, 5 speeds, duals, front arb, superchargers and 37s. I have manual hubs where he has add. I'm on my second front diff from spider gear failure (common) and nothing since going arb in the front and welding on bigger steering stops. He's broke one stub shaft (which it looks like everyone has agreed would be the next weak point) and the either broke a couple ring gear bolts or had them back out taking out all of it. Which leads me to my point, i think the ring gear would be the next weak point, or for manual hub guys maybe the hub itself.

True, being careful on the throttle and being fruitful with the front locker is the key, but where is the fun in that?? I do most of my wheeling in the snow and sometimes you need all of it

Fuck, that is badass! Hearing that supercharger bouncing off the rev limiter is wild! Fuck yeah!

I’m wondering if it’s even worth going to RCV’s with these stock diff’s. I’d think that until there is a better solution for the stub shaft, there is not much point in finding that the stub shaft is not far behind on being the next weak link. Maybe we can hit up RCV and see if they can make a 300m stub shaft? But again, is that polishing a turd like the guys that put chromo axles in a D35? What’s gonna be the cost to build up a 7.5” vs a full IFS axle swap?

I love the idea of running RCV’s, but hate the idea of having to replace a stub shaft. Pulling the front diff sucks fucking balls! Plus the ADD tube bends too easy.

 

[theesotericone]

I love the idea of running RCV’s, but hate the idea of having to replace a stub shaft. Pulling the front diff sucks fucking balls! Plus the ADD tube bends too easy.

Pulling the front diff isn't that bad but it's nowhere as easy as just swapping a CV. With that said guess what just went up on RCV's site?

https://www.rcvperformance.com/ulti...-toyota-tacoma-95-5-04-and-4runner-95-02.html

 

[4runner DOA]

Pulling the front diff isn't that bad but it's nowhere as easy as just swapping a CV. With that said guess what just went up on RCV's site?

https://www.rcvperformance.com/ulti...-toyota-tacoma-95-5-04-and-4runner-95-02.html

You haven't had to pull (or in my case help put it back) @AssBurns Front diff. Be a lot easier if there wasn't a jack in the way pushing the motor up. Hahaha.

 

[theesotericone]

You haven't had to pull (or in my case help put it back) @AssBurns Front diff. Be a lot easier if there wasn't a jack in the way pushing the motor up. Hahaha.

Nope. But I've pulled mine 3 times and it's never had a jack in front pushing the motor up. The "secret" is to remove the two mounting arms from the diff before you pull it. Then it's just a matter of being strong enough to bench it over the rear mount stud bolt and not have it fall on your face. A knee helps a lot here. Keep in mind I've never had help doing it. A second set of hands would make it so much easier. lol