View Full Version : RCV Performance 930 CV plunging axle

08-23-2015, 11:33 PM
On RCV Performance website they show a plunging axle they make for a Polaris 1000 rzr . They make custom 930 CV plunging axles , they do not show this on there website. The axle came with CV boots, CV boot flanges and CV bolts. The axle requires you use a non-plunging CV on one end of the axle, you can use a plunging CV on the other end of the axle. I got the non-plunging CVs from RCV Performance, the end of the axle spline that goes into this CV is larger in Diameter than a 930 CV plunging axle. So you need to plan which end of the axle will have the non-plunging CV. The axle acts like it has a return spring inside it, if you compress the axle and let go of it the axle will pop back to full length. The axle has 3 inches of plunge. The axle uses ball bearing in slots to prevent the axle from binding under power and braking. See the Link for details on how it works. This axle is suppose to not have the binding problems that spline axles have. I have not drove the buggy yet.

RCV Ultimate UTV Axle for Polaris XP 1000 Rear (http://www.rcvperformance.com/product-details.aspx?sku=54063-UPA)


08-23-2015, 11:37 PM
The end of the axle that goes into the non-plunging CV





08-23-2015, 11:42 PM
The plunging part of the axle






08-23-2015, 11:50 PM
The end of the axle that goes into the plunging CV






08-23-2015, 11:54 PM
Axles on the buggy. The axles have 2 inch clearance to the trailing arms the pictures make it look like its less




08-24-2015, 01:10 AM
Its a really cool part but double plunge? Do you need a plunge axle With a plunge cv? I always thought the axle plunge was so you could run two NON plunge cv's..

08-24-2015, 05:11 AM
Cool, super travel now. Kfab had a set of similar axles a while back on the dez. We had used those splined shafts with ball bearings successfully on a few projects.

It may just be my ocd side, but they should have necked the axles down after the splines to prevent them from causing a stress riser. They will either fail there, or at the snap ring before the sliding splines.

Another small rant, but what is with the money gouging monopoly on non plunging 930's? $280 bucks? C'mon! I paid 180 each 5 years ago.

08-24-2015, 12:14 PM
Cool, super travel now. Kfab had a set of similar axles a while back on the dez. We had used those splined shafts with ball bearings successfully on a few projects.

It may just be my ocd side, but they should have necked the axles down after the splines to prevent them from causing a stress riser. They will either fail there, or at the snap ring before the sliding splines.

Another small rant, but what is with the money gouging monopoly on non plunging 930's? $280 bucks? C'mon! I paid 180 each 5 years ago.
Holy ouch, I thought 180 was steep 4 years ago. I'll stick to cannibalizing F150 stuff. If F150s fail, time for GM 1-Tons- same old 33 spline stub (might need some clearance cuts). But one needs to be ready to pony up for custom axles.

I was looking at them thinking the same thing- where's the twist section?


08-24-2015, 10:43 PM
I have mid-board hubs on my trailing arms , the hubs have plunging CVs. That is why I have have a non-plunging on one end of the axle and the mid-board hub plunging CV on the other end of the axle. Non-plunging CV are about 3/8 inch narrower than a plunging CV. Since the CV is inside the mid-board hub you can not put a CV that is narrower and still be able to assemble the mid-board hub.

On the RCV one piece straight axles the ends of the axles where the splines are cut are a larger diameter to reduce the stress riser. The correct method.

When I got the axles I saw how they cut the CV splines into the axle shaft, was surprised with how they cut the CV splines , making a stress riser. That is why I showed close up the splines in the pictures , to show how they did it. After the custom axles shows up in the mail its too late to do anything but to hope for the best.

08-24-2015, 10:45 PM
I hope they work.

I had horrid problems with plunging axles and there's no neck down on the splined area, so there's gonna be a huge stress riser there.

08-24-2015, 11:01 PM
The RCV Performance non-plunging CV has a lot of stiction in it. I packed them with grease and moved the CV inter race around to work the grease inside. The stiction reduced a little, but it still takes about 15 lbs of force to move the CV inter race to change its angle. I called RCV they said this normal and the CV will free up after a couple short rides. They said to do 3 rides of about 5 minutes at or below 50% max power to break every thing in.

08-25-2015, 02:32 AM
Mine were tight when new, they freed up in short order though. Any rezeppa joint off of a fwd car is the same though.

Did they offer the no questions asked warranty on these?

08-25-2015, 08:57 PM
I have had a lot of problems with axles breaking in the spline out at the mid-board hubs.

My first set of axles where 4340 steel and broke in the axle spline inside the mid-board hub after about 2 hours total time on them. The ends of the axle were a larger diameter with the spline cut in them , the correct method to make a axle. I replaced the inter races on the CV after the axle failure.

My second set of axles where RCV performance one piece straight axle made of 300 M steel. The ends of the axle were a larger diameter with the spline cut in them , the correct method to make a axle. After about 2 hours total time, one axle broke in the spline inside the mid-board hub. I sent the axle back to RCV and they replaced it no questions. I put the new axle on and when riding and my other axle that had 2 hours on it, broke in the spline inside the mid-board hub 10 minutes into the ride. I sent this axle back to RCV and ask them to look at closely to see if we can figure why it breaking. I gave them all the details of my buggy and pictures and measures of axle side movement at full drop and shortest distance and full compression. RCV said my axle had a lot of wear in the spline that goes into the mid-board hub. They said to looked like most of the axle plunge was being handled by axle plunging through the CV race and the CVs plunge was not handling much of the total plunge. RCV said they have seen the same thing on axles used in mid-board hubs before. RCV said when you get a lot of wear on the axle spline the axle starts to hang up on the inter race of the CV and puts a axial load on the axle. The axial causes the axle failure.

RCV said I needed to have the spline ends on the axle just wide enough to hold the CV inter races so I have no axle plunge through the inter race of the CV. This is when they told me about there plunging axles. They if I paid the difference in price between my old one piece straight axles and the plunging axles they would replace my broken axles with plunging axles. I paid $250 per axle to get the plunging axles. I order RCV non-plunging CVs.

I think these axles only have a 90 day warranty , I am not sure.

I did this to try something different because I could not the one piece straight axles to work with my mid-board hub.

I think part my problem is the type on track I drive on. Its a old farm field that had been plowed and there is a 6 to 8 inch bump every 2 feet all the way around a 2.5 mile course. I think all bumps are causing the CV to wear the axle spline at a fast rate

08-26-2015, 10:55 PM
These are pictures of what the broken one piece straight axles looked liked. This is the of the axle that was inside the mid-board hubs. I had 4 axles break like this.



08-27-2015, 02:36 AM
Was that your left axle? I think I can see where the crack started.

Were the axles hitting the mid boards before or after they broke? There is some major wear half way down the splines.

It looks like the cutter had an extremely sharp radius, or the transition at the root of the splines has an odd step in it.

08-27-2015, 11:45 PM
The axles where not hitting the mid-board hub the cover that goes over the outside of the mid-board hub is 4.75 inches away from the outside part of the CV. With a Mid-board hub the axle can plunge through the CV inter race and the closed surface is 4.75 inches away from the end of axle.

I do not which side axle is in the picture. I only took one picture of a broken axle out of the 4 axles I broke.

08-28-2015, 12:46 AM
On the broken end, there's what looks like a wear groove. (What plk is talking about). What caused that groove?

08-28-2015, 04:13 PM
On the spline of the axle there is a lot wear from the axle plunging through the CV inter race.

The smashed down spots going around about 40% of the outer diameter of the broke off part of the axle, are most likely from the CV cocking and digging into the axle when the axle broke. The out board inter race of the CV had area about 40% around the inter diameter on the edge had a smashed down spots like the axle.

The axles would break when I was power siding out of a turn hard on the gas. I would start to have problems steering the buggy at that point I would know the axle is most likely broken and let off the gas. So I was hard on the gas for 40 to 50 feet with a broken axle before I let off the gas. Then I would drive about a mile back to my truck at 10 mph and drive it up on to the trailer. It is always the out wheel for the turn that breaks. I have broken axles in both left and right hand turns.

The axle that I asked RCV to look closely at, they looked at it with there equipment and said the crack started in the axle spline at the spear tip looking part of the broken axle.

My first set of mid-board CVs where the CVs Gear One Racing install, I think they are GKN CVs.

When installed the RCV straight one axles , I installed RCV CVs with a 300 inter race.

All the axles broke the same way and looked the same and had a lot of wear on the axle spline on the mid-board hub side.

The inboard part of my axle at the gearbox has never given me any problem the axle spline shows no wear on any of the axles. This end of the axle has clips just wide enough for the CV so there is no axle plunging in the CV inter race.

I think the track I ride on is the problem, it is a old farm field that has been plowed and the ground has turned rock hard because the drought Texas has had for years. Every 2 feet there is 6 to 8 bump caused by the last time it was plowed years ago. I have 2.5 mile track set up so the buggy takes a beating.

08-28-2015, 06:10 PM
It could be your trailing arms flexing inward, binding the axle, which would definitely break them when the suspension compressed. A 24 inch axle makes for a nice lever, and combined with the torque, would spell disaster.

08-29-2015, 03:11 AM
Completely clipped solid on the inside asks the outboard to do all the work.
It halfs the load when both can do the slipping.

08-29-2015, 01:28 PM
On my old one piece straight axle set up , I had plunging CVs on both the inboard and outboard sides of my axle. The inboard side the CV bolted to a drive flange. The drive flange has a dome shape that would allow a enough room for the CV plunge. So putting clips on the inboard axle done to stop the axle from hitting the drive flange and tearing up the end of the axle and the drive flange. So on the inboard side weather I had clips on the axle or not the CV would still plunge 1.25 inches.

08-29-2015, 01:35 PM
I think you have to determine what's chewing on that axle in the middle of the spline.
That wear mark should not be there.
What's your maximum angle at full drop?
Do you use limiting straps?
Have you disconnected the shock and run it thru the travel while rotating as well to watch for abnormalties.
I think it's going to come down to cv angle.
You won't get away running more than 25 degrees on a 930.
I've been running the same setup for 12 years with no issues at all.
These cars should never break these axles
I spoke at length with the RCV factory rep at Dunefest two weeks ago and they make a very nice product but pricey
Good Luck I can't wait to see what you find

08-29-2015, 07:14 PM
At full drop my axles have 22 degree angle with just the shocks bolted up. That is with my limiting straps unbolted.
I have my limiting set up to act in the last 1.5 inch of travel.
I have took the springs off the shocks and removed the pressure in the shocks and took the outside cover off the mid-board hub and had the CV boots off so I could check for clearances and ran them through the full range of travel.
I checked side play (inboard / outboard) movement
full drop 0.375 inches free play
short distance 1.25 inches free play
full compression 0.65 inches free play

I did this when I first got the axles for the buggy and each time replaced a axle I repeated the process.

I am not saying any of the products I am talking about are bad, RCV makes good stuff and Gear One Racing makes good stuff. There is something about my buggy or the type of riding I do that is causing it. Where I ride there are not jumps so I can rule that out.

RCV has been helpful and they said they I have this type thing happen with mid-board hubs where the axle splines inside the mid-board hubs tear up.

My trailing arms are 1.25 diameter 0.120 wall thickness 4130 steel TIG welded. There are around 15 buggies built like mine. When we all started converting to CVs they keep there micro-stubs on and had to take about 4.5 inches travel out of their rear ends to get the axle angle to 22 degrees. When I converted I went with the mid-board hubs so I could keep all of my travel. I had the shop that built they buggies convert my trailing arms and I did the rest of the work. The guys that have these buggies send E-mails to each other about things we learn. Some of the guys converted to American make 930 CV stuff and others to China make 930 CV stuff all of them keep there micro-stub set up on there trailing arms. Non of these guys are having problems. My trailing arms look very strong so what ever amount of flex I am getting in the trailing arms is in the elastic range , there is no permanent displacement in the arms. When I measure alignment and camber of the rear wheel there has been no change.

08-29-2015, 07:37 PM
So the micro stub guys aren't having the problems(galling or breaking on the axles) that you are having with the mid-board hubs?

08-29-2015, 11:30 PM

08-30-2015, 12:00 AM
Kinda narrows it down doesn't it?

08-30-2015, 12:30 AM
Again I am not saying any of the products I am talking about are bad. When I buy stuff I research the subject and usually buy top of the line products. I having this problem, I can not say I fully understand what is happening or that I know the answer to this problem.

RCV has been helpful and they say the plunging will solve my axle breaking problem so I am hoping for the best. It wish RCV would not have cut the axle splines in the plunging axle the way they did. Time will tell if this is the solution.

08-30-2015, 02:28 AM
This is crazy 22 is very safe.

So is the spline getting nicked by the cage or the outer race ?

Because I see from your photo that the axle was trying to fracture at that nick line and most all twist off right at the spline transition

I have an big V8 car in here that I'm replacing twisted off 4340s with 300Ms but it took him 8 years to do it

08-30-2015, 02:34 AM
Is the pocket where the axle goes into the midboard cupped, or is it flat? That fracture looks like combined loading to me.

08-30-2015, 04:54 PM
The wear pattern on the splines looks like something was binding, got to the point it couldn't slide and blamo.
Post some rear end pics, the plunge numbers seem odd? Trailing arms extend with droop, semi trailing arms not as much. Those numbers go the other way.

Also if your tearing up drive flanges it might be a sign that the axle is binding in the midboard.
According to your lowest and highest clearance number plunge was less than an inch?
Might have been better to solid clip the mid-board.

08-30-2015, 11:21 PM
The drive flange is not damaged, the drive flange only has enough room to handle the plunge in the CV that is why I clipped the axle to the CV at the drive flange. The CV has 1.25 inches plunge at the CV.

The mid-board as a cup shape cover so the end of the axle is 4.75 inches away from the end of the mid-board hub cover. There are not hit marks on the cover.

The axle has 3.0 inches of plunge from short distance to full drop. Each CV only as 1.25 inches of plunge so I need 0.6-0.7 axle plunge through the CV inter race. If I clipped the axle to the CV at the mid-board hub I would not have enough plunge.

The thing that is controlling short distance side to side free play I measured is the CV at the drive flange only has 1.25 of plunge and since the axle is clipped to this CV. So the axle can not move that CV plunge at the drive flange.
Its not like micro-stubs where you have something the axle can hit on the backside of the CV. So mid-board numbers are not going to look like the normal numbers you see on micro-stubs.

RCV looked at the axle with a digital magnifying tool and said the CV inter race was grinding up the axle spline and caused the inter race to dig into the axle which was putting a axial load on the axle which caused the failure. They said they have seen this before.

What I take away from this experience and talking to RCV is I should not of set up my axles planning on the axle spline being able to plunge through the inter race on the CVs. I should of had the axles built so the axle splines are only wide enough to trap the CV inter races with clips so the axle can not plunge through CV inter races on both ends of the axle. So all my plunge would be handled by only the CV joint , there is only 1.25 plunge in each CV joint. I would have had to remove about 4.5 inches of suspension travel out my rear if I only have 2.5 inches of total plunge. If I would have done this I most likely would not have axle breaking problems. Trying to plunge 0.5 inch of axle spline through the inter CV race is the problem, I was thinking that mid-boards are designed to do this, but it causes problems. If the new plunging axles I got do not work out this is what going do next.

08-31-2015, 02:25 AM
I machined the 930 star .375 deep so my spiralocks will slide inside the cvs on both ends

Buggy Builder
12-12-2015, 10:59 AM
The axle has 3.0 inches of plunge from short distance to full drop. Each CV only as 1.25 inches of plunge so I need 0.6-0.7 axle plunge through the CV inter race. If I clipped the axle to the CV at the mid-board hub I would not have enough plunge.


This is your problem.

You designed your suspension so the spline MUST slide thru the CV joint.

RCV told you their shaft failed because there was excessive sliding between the shaft and CV.

12-12-2015, 04:50 PM
Every trailing arm buggy out there has the axle plunging in the star. This should not be an issue. Polishing the splines on both the axle and star goes a long way. With the axle body the same diameter as the splines, the splines will want to twist before the axle body. This will lock up the star on the axle.

12-11-2020, 10:29 AM
I have these same axles on a buggy. Glad to know this.

BTW, RCV is the worlds worst company to deal with. I had a guy yelling at me on the phone. All I wanted was replacement CVs for the custom axle they built. Instead they told me they couldn't, and wouldn't help me because they are not experts on every axle and have no way of knowing what CVs I have. THEY MADE THE AXLES AND CVS! I also gave them the CAD drawing of the axle, THEIR OWN CAD DRAWING! I also paid for next day air shipping. 3 days later I call and they forgot to enter the order into the system somehow, that's what i was told anyways. Then they sent me the wrong CVS! So I call them and they get mad at me for calling them so much. WORST COMPANY EVER!

Anyways, their "reason" for why this failed made absolutely no sense, like the reply above, all trailing arms have plunge and the axle sliding through the CV star. What happened to their No Questions Asked axle and CV replacement policy?