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914World.com _ The Paddock _ Issues with Beetle CV joint failure?
Posted by: stownsen914 Apr 22 2015, 09:10 AM
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 ...
Attached image(s)
Posted by: SirAndy Apr 22 2015, 10:53 AM
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/4055868/9926705.htm
Posted by: malcolm2 Apr 22 2015, 11:06 AM
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.
Posted by: malcolm2 Apr 22 2015, 11:24 AM
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.
Posted by: stownsen914 Apr 22 2015, 12:14 PM
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 
Posted by: Jetsetsurfshop Apr 22 2015, 12:48 PM
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.
Posted by: mskala Apr 22 2015, 12:57 PM
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.
Posted by: Racer Chris Apr 22 2015, 02:59 PM
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.
Posted by: ThePaintedMan Apr 22 2015, 07:05 PM
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.
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Posted by: Randal Apr 22 2015, 10:54 PM
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.
Posted by: stownsen914 Apr 23 2015, 11:01 AM
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 ...
Posted by: SirAndy Apr 23 2015, 11:11 AM
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.
Posted by: SirAndy Apr 23 2015, 11:12 AM
They are NOT stock 914 CVs, see my post above ...
Posted by: stownsen914 Apr 23 2015, 11:35 AM
They are NOT stock 914 CVs, see my post above ...
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?
Posted by: malcolm2 Apr 23 2015, 08:02 PM
Did I read that the balls are too small? Or at least have too much variability.
Posted by: stownsen914 Apr 24 2015, 03:57 AM
Did I read that the balls are too small? Or at least have too much variability.
Was that with a certain brand of CVs?
Posted by: Racer Chris Apr 24 2015, 07:28 AM
...
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.
Posted by: Mugs914 Apr 24 2015, 11:18 AM
...
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?
Mugs
Posted by: Racer Chris Apr 24 2015, 01:18 PM
...
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?
Mugs
I believe its due to longer slots in the cage.
Posted by: Matt Romanowski Apr 25 2015, 09:16 PM
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.
Posted by: McMark Apr 25 2015, 10:51 PM
I'm convinced that my failure and apparently this one are just low quality control or poor manufacturing. I approach these bug CVs as just having a higher failure rate, sort of like the IMS bearing issues that trouble early boxsters. Not every one has an issue, plenty of people have run them without problem, but every once in awhile you get the one that kills itself prematurely.
What Andy has brought up does seem to pertinent as well. Some brands of replacement CVs are 'looser' out of the box. There are some that almost feel like they're going to fall apart new out of the box, some are tighter. I would say the test is that you open the box, and turn the cv vertical and if the center portion drops/extends on its own, its too loose.
Posted by: mskala Apr 26 2015, 06:59 AM
Well, I may have a new data point as of last night.
I lost the right inside CV as I spiritedly applied throttle in first after getting moving.
Cage broke in 3 pieces but bolts were tight and nothing came physically apart.
These are Meyle Germany parts, like Chris's and I can't remember where I bought
these but they have the same o-ring and all. Probably 4 years or so on them.
Putting a bunch of pictures below to see if this is a sign of anything abnormal.
* The inside of the cage has distinct rub marks that could only have been before
breaking.
* The axle end and the stub do not have anything that looks like excessive travel
allowing the pieces to hit.
* The boot sheared off and flung some grease, but I likely after failure.
Posted by: Bartlett 914 May 3 2015, 12:01 PM
Maybe a little off topic here but I wanted to add an observation I have had on CV problems. Twice I had mine work loose at the transmission. Proper lock washers, bolts and torque. I turned the face of the hubs in a lathe and found they were not flat. Once these work loose, the flange gets distorted. The spots around the threaded holes become high. I removed about .005 and they cleaned up. I found this on other hubs also. No problems since. Without perfectly flat mating surfaces, you will face troubles.
Posted by: stugray May 6 2015, 12:16 PM
A couple of observations I have made:
1 - I have ~4 sets of "stock" used CVs at home (lobro). They have very different amounts of "stick-out" or movement from side to side when fully assembled.
I have pics but I will have to dig for them.
2 - When we jack our cars up in the air, I cringe every time as the rear trailing arms drop so far and hyper-extend the CVs. I intend to make travel limiting straps/cables but havent done it yet.
I suspect that hyperextending while jacking does not permanently damage the CV as minimal forces are applied and CV rotation in this position is minimal.
So based on these two observations above I believe that IF you get a set of CVs that does not "extend" as far as it should AND you track your car, you stand a bigger chance of hyperextending a CV while it is turning (inner wheel lift).
(See SirAndy's recent thread about two wheel lift in the paddock forum.)
Also with inner wheel lift, the lifted wheel can spin up and get a huge impulse of torque when it sets back down.
I suspect that this puts a strain on the CV.
This is also something that most street-only cars would never experience.
Heres the pics of the CV extension difference between two CVs:
I'm sure someone will be able to identify those different CVs but I didnt write down the part #s.
I could dig them out.
Posted by: 914_teener May 6 2015, 10:33 PM
I thought this was brought up already.
The type I CV's and the "stock" 914 have different degrees of freedom.
I believe the 914 have 27 deg. and the Type 1 21 degrees.
Posted by: Racer Chris May 7 2015, 06:14 AM
...
I'm sure someone will be able to identify those different CVs but I didnt write down the part #s.
...
The one on the right, with the most extension is a type 1 CV.
Posted by: mskala May 7 2015, 07:01 AM
Unless I'm wrong about how CV's work, the amount of extension is related to
the length of the slots in the cage (all else being the same).
The EMPI Type 1 units I just got from Chris have a slot length of about 960mil.
The Meyle Type 1 units I removed had a slot length of about 900mil.
I'm not an expert here, just an FYI.
Posted by: Racer Chris May 7 2015, 08:12 AM
Unless I'm wrong about how CV's work, the amount of extension is related to
the length of the slots in the cage (all else being the same).
Actually, my observations have not supported that. The balls never reach the end of the slots in OE 914 CVs.
It may be that the angle of the grooves is different.
Posted by: malcolm2 May 8 2015, 09:17 AM
QUESTION>>>> I replaced both passenger side joints, inner and outer with Chris's modified type 1 joints.
I have done nothing with the drivers side. As far as I know they are 914 type, maybe original.
Seeing and hearing about the differences, is there a problem doing that on a daily driver? Would I experience any issues, or even notice any? Or maybe end up with excess wear on either type of joint?
Just curious,
Clark
Posted by: malcolm2 May 11 2015, 09:35 AM
Bump for my ???
Posted by: Racer Chris May 11 2015, 09:35 AM
Bump for my ???
It shouldn't matter.
Posted by: stownsen914 May 12 2015, 10:52 AM
After the fairly quick failure of the EMPI joint in my racecar, I ordered a set of the Lobro CVs from PMB and asked Chris to do the mods for the gasket groove and pins (thanks for turning that around quickly Chris), and tried those at Monticello this past weekend. I had other issues with the car, but the joints held up fine. I have to pull the motor and trans, so will look at the joints and flanges more closely and report back again.
Interesting about the 21 vs. 27 degree range for the Beetle joints. That should be fine for my car, as it's set up to have limited suspension movement. The axles are almost straight at ride height, and only deviate from that by a couple inches of upward and droop travel, so I think I should be OK.
Scott
Posted by: naro914 May 12 2015, 02:17 PM
Scott
First of all, sorry to hear all the issues you had at Monticello last weekend. Nadine said she really felt bad for you...not the best way to start your PCA Racing career!! Hope you can sort out all the issues...
Regarding CV's, what engine are you running and how much hp? I ask because I recently replaced the CV's on our car. Originally, I was just doing a CV service, re-lubing up everything. But the races and everything in the CV's were so worn down, I decided to replace them. I also got new axles from Sway-Away since the ones that were in there were too short and being overextended.
Because of the higher hp, I went with very beefy CV's and much bigger output flanges - from something like a later 930 or so, can't remember where they came from but I do have a spare CV in he trailer and can get the part # if you're interested. My mechanic got these for his RSR and has not had a problem, so I decided to go that route. Problem is...you need to find all the correct individual pieces, from output flange, CV, axle, CV and stub axle at the wheel that all fit together correctly. But if you're running a bigger/stronger engine (I saw your in GT4?), I would go with stronger CV's...
Just my thoughts...
Posted by: naro914 May 12 2015, 02:30 PM
Also... are you running 5 lug wheels?
This was a very good thread that started me down the path..originally just to lube the CV's, then....read on....
http://www.914world.com/bbs2/index.php?act=ST&f=2&t=91963
Posted by: stownsen914 May 12 2015, 06:39 PM
Thanks Bob. It was great to see Nadine after all these years. Hopefully I'll get to see the two of you and one of the teeners at the track sometime soon.
It was sort of a bad kharma weekend for me at the club race. Silly things going wrong all weekend, and then I spun a rod bearing ... I think I'll focus on my 911 for now and worry about the engine over the winter, and get the 914 ready for next year.
The 914 has a 2.7L engine putting out something like 250 hp. Since the original 914 CVs held up for so long, I'm going to see how the Lobro Beetle CVs do. Any more hp, and I'd want to upgrade for sure to something like what you have.
Scott
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