Issues with Beetle CV joint failure? Options

[stownsen914]

Hi all,

With 914 CV joints being NLA now, I recently tried out Beetle CV joints when my old ones wore out on my 914/6 race car. I understand they are made by EMPI. I am using the same 914 axles I've used for years. After about 30 minutes of track time, one of the Beetle joints failed (the inner one on the right side of the car). Basically the joint seems to have been plunging too far inward and the lateral force seems to have just forced the joint apart. No broken parts are immediately apparent. The joint seems to have just fallen apart!

I also noted that the inner races of the joints seem to be gouging the output flanges on the trans. This occurred on both sides fo the car. I had noticed some of this wear previously, but it seems to have accelerated significantly with the Beetle joints (especially considering only 30 minutes of use). See the pics below. It's hard to tell from the pics, but the wear spots are basically gouged into the flanges about a millimeter or so deep.

I never had any failures or unusual wear with the 914 joints I used for years, so I am at a loss what happened here. Anyone have a similar issue with Beetle joints? I'm wondering if I should be trying Lobro or other joints, or a different setup entirely ...

[SirAndy]

Yes, they over-extend and fail. There have been several threads about this, the first failure of this kind i saw was maybe 6 years ago on McMarks car.

However, there is a version that does work and i believe PMB sells them now.
http://www.pmbperformance.com/catalog/item...868/9926705.htm

(IMG:style_emoticons/default/beerchug.gif)

[malcolm2]

Racer Chris from Tangerine Racing has also developed a joint.

http://www.tangerineracing.com/transmission.htm

link to his Tranny page. Scroll down and you will see the joint or the whole axle for sale. I am sure you can call him or PMB and both will tell you the scoop.

I went with the Tangerine unit. Installed 2 joints on one side. Couple thousand miles so far everything is A-OK. Make sure to get a bunch of the paper or cork gaskets and new schoor washers.

While we are on the subject. I have been seeing some grease spatter from any and all joints. I have paper gaskets, is that something to live with? very small specs of grease have been flung on the under side of the trunk.

[malcolm2]

I knew I had a picture.... So actually the grease is coming from the "cap". The bolt side of the joint. This is on the OLD probably original CV joint. Don't have a shot of the CFR one.

Is this just a flaw we have to live with? You can see where it is on the starter in the background.

[stownsen914]

The cap gets distorted easily since it's thin metal, and can seep. I've fixed this in the past by removing the cap, caregully cleaning the perimter that mates with the CV joint, and sealing the surface between the cap and the CV with some RTV.

In the mean time, wrap some duct tape around the entire perimeter of the CV (IMG:style_emoticons/default/smile.gif)

[Jetsetsurfshop]

My drivers side made a nice grease line too. It seems that the gaskets doesn't compress on my car. I'll have to look at it closer.
(IMG:style_emoticons/default/driving.gif)

[mskala]

The Tangerine ones have a step on the outside. This is sealed with an o-ring
which is hidden under the flange. This should stop grease from coming out there.

[ChrisFoley]

Yes, they over-extend and fail.

Scott's problem doesn't appear to be related to that mode of failure.
Note the amount of "damage" inside the output flange which indicates the axles are bottoming not hyperextending.

Scott's failed CV is one of mine.
After McMark's issue we carefully inspected the CVs we work with and couldn't find anything that would lead us to believe our assemblies would suffer the same result.
What was written by Eric and/or Mark didn't just fit with our findings.

I know of only one other on-track failure of the ones I sell, which was on a Lemons car in the mid-west. That one went 4 hours before the unloaded side came apart, probably by hyperextension.
Matt Romanowski has lots of track time in his 3 liter car with our axles installed.

In both failure cases there's no evidence of the cage being damaged.
I have a test planned to hopefully gain further understanding of what happens.

[ThePaintedMan]

In both failure cases there's no evidence of the cage being damaged.
I have a test planned to hopefully gain further understanding of what happens.

Weird. (IMG:style_emoticons/default/confused24.gif) (IMG:style_emoticons/default/popcorn[1].gif)

[Randal]

Hi all,

With 914 CV joints being NLA now, I recently tried out Beetle CV joints when my old ones wore out on my 914/6 race car. I understand they are made by EMPI. I am using the same 914 axles I've used for years. After about 30 minutes of track time, one of the Beetle joints failed (the inner one on the right side of the car). Basically the joint seems to have been plunging too far inward and the lateral force seems to have just forced the joint apart. No broken parts are immediately apparent. The joint seems to have just fallen apart!

I also noted that the inner races of the joints seem to be gouging the output flanges on the trans. This occurred on both sides fo the car. I had noticed some of this wear previously, but it seems to have accelerated significantly with the Beetle joints (especially considering only 30 minutes of use). See the pics below. It's hard to tell from the pics, but the wear spots are basically gouged into the flanges about a millimeter or so deep.

I never had any failures or unusual wear with the 914 joints I used for years, so I am at a loss what happened here. Anyone have a similar issue with Beetle joints? I'm wondering if I should be trying Lobro or other joints, or a different setup entirely ...

The CV set up that Chris sells is likely good.

I had turbo 944 CV's on 222 and they never failed. The stock ones only lasted three 40 second runs. Lots of instructional information about installing 944 CV's on this site.

[stownsen914]

The CV set up that Chris sells is likely good.

I had turbo 944 CV's on 222 and they never failed. The stock ones only lasted three 40 second runs. Lots of instructional information about installing 944 CV's on this site.

Weird thing is thoiugh - I used the same set of stock 914 joints for many years on this car wtih no issue at all. The new one failed almost immediately. That would argue that the size/durability of the joint is not the issue.

I'm going to take a closer look at the failed joint to see if I can figure out what caused it to fail. CV joints should not just pull apart ...

[SirAndy]

After McMark's issue we carefully inspected the CVs we work with and couldn't find anything that would lead us to believe our assemblies would suffer the same result.
What was written by Eric and/or Mark didn't just fit with our findings.

Eric's article is a bit misleading as it seems to put the blame on the inner cage.

After McMarks failure, we went back and compared the new VW CVs with original 914 ones and noticed that on the VW CVs, the inner portion had significantly more side to side travel.
So both extending or compressing them can result in a failure when force is applied at the same time. At that point, they basically just fall apart.
(IMG:style_emoticons/default/popcorn[1].gif)

[SirAndy]

Weird thing is thoiugh - I used the same set of stock 914 joints for many years on this car wtih no issue at all.

They are NOT stock 914 CVs, see my post above ...
(IMG:style_emoticons/default/shades.gif)

[stownsen914]

Weird thing is thoiugh - I used the same set of stock 914 joints for many years on this car wtih no issue at all.

They are NOT stock 914 CVs, see my post above ...
(IMG:style_emoticons/default/shades.gif)

By "same" I meant I used a single set of CVs for many years - not trying to imply that the Beetle CVs are the same as the old 914 ones.

So are there differences between the Lobro Beetle CVs that are currently available vs. Empi or other brands?

[malcolm2]

Did I read that the balls are too small? Or at least have too much variability.

[stownsen914]

Did I read that the balls are too small? Or at least have too much variability.

Was that with a certain brand of CVs?

[ChrisFoley]

...
on the VW CVs, the inner portion had significantly more side to side travel.
...

That is true.
However, that shouldn't be enough to allow the joint to come apart unless there's a huge angular misalignment of the axle.

One idea I'm looking more closely at is possibly installing teflon (or similar) buttons on the ends of the axle to prevent the shaft from travelling so far that a CV could allow a ball to come out of the track.

[Mugs914]

...
on the VW CVs, the inner portion had significantly more side to side travel.
...

That is true.
However, that shouldn't be enough to allow the joint to come apart unless there's a huge angular misalignment of the axle.

One idea I'm looking more closely at is possibly installing teflon (or similar) buttons on the ends of the axle to prevent the shaft from travelling so far that a CV could allow a ball to come out of the track.

I've seen some CVs that have a stamped metal 'cap' that goes between the CV and the flange, presumably to limit the axle plunge and to retain grease. Taylor or someone may have one that will work.

I'll be really interested to know why the Empis allow so much more lateral movement of the axle. Is there some difference in the actual design of the joint or is it just a difference in tolerances? (IMG:style_emoticons/default/confused24.gif)

Mugs

[ChrisFoley]

...
I'll be really interested to know why the Empis allow so much more lateral movement of the axle. Is there some difference in the actual design of the joint or is it just a difference in tolerances? (IMG:style_emoticons/default/confused24.gif)

Mugs

I believe its due to longer slots in the cage.

[Matt Romanowski]

I've got years of time on Chris' CV joints with no trouble. I can't even say that we've repacked them.

If Chris tells me when we bought them, I can tell how many miles/hours are on them.