Issues with Beetle CV joint failure? Options

[McMark]

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.

[mskala]

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.

[Bartlett 914]

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.

[stugray]

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.)
(IMG:http://www.914world.com/bbs2/uploads/post-179-1430802497.jpg)

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:
(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1430959850.1.jpg)
(IMG:http://www.914world.com/bbs2/uploads_offsite/i366.photobucket.com-10819-1430959851.2.jpg)

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.

[914_teener]

(IMG:style_emoticons/default/agree.gif)

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.

[ChrisFoley]

...
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.

[mskala]

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.

[ChrisFoley]

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.

[malcolm2]

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

[malcolm2]

Bump for my ???

[ChrisFoley]

Bump for my ???

It shouldn't matter.

[stownsen914]

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

[naro914]

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...

[naro914]

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...f=2&t=91963

[stownsen914]

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