Why did my new cv boot split?

[RWebb]

some of the Vanagoneers among us have no doubt seen people on Samba complaining about cheap boots

it may be that Chinese Drywall Disease has reached GKN...

[Joe Bob]

As I opined....GKN is passing off a defect in the boot to "use on the track". It's an excuse and not a good one. The BIG issue is not the cost of the part but the cost and time of replacement. With the exception of tranny fluid, I hate dealing with CV grease the most.

I wonder where GKN makes the boots and if they recently changed molds or material mix.

[Jeff Burger]

Not necesarily the problem here but if you let the axle drop to fast and too far it will bend the boot mounting metal out of round. If you don't straighten it, it will put additional stress on the boot and will eventually tear it.

[RWebb]

I wouldn't conclude that GKN is passing off a defect in the boot to use on the track - they might be, but that header set up is seriously hot.

IIRC, Steve W. has posted some sort of high zoot boot they use on race cars - probably cost about as much as a complete CV, but...

[Walt Fricke]

The GKN CVs (they seem maybe the only maker, as they are combined with Lobro per the box) I bought about two years ago were perplexing. The inner channels, which I recall from past replacements as being very smooth, if not as polished as, say, the balls, were striated. The body was silver instead of a dark uniform color, except where it was blue, which appeared to be where the steel was heat treated (maybe just fine, treatment would be needed only on the wear surfaces).

But the biggest disappointment was the cage. Balls are supposed to pop into their grooves, and stay there. These new cages were like old, worn cages - the balls would just slip through.

I don't know if this is really going to affect anything. Tight cages are something others have said are necessary for a CV, and loose ones a sign of a CV which is worn and needs replacement. I don't know how important cage fit really is. Mine have run OK, but I don't place any long term faith in that observation, as the hours aren't high enough.

So maybe there is an overall decline in quality here, both in boots as well as the CVs?

[cmcfaul]

I had a period where the CV boots would tear for no reason once a year. Replacing them is a huge PITA. I got fed up and ended up replacing the CV's entirely with new CV's and half shafts. That was about 5 years ago and no tears.

My logic was that perhaps the CV's were warn and creating internal heat that was causing the boots to tear.

Either way, glad I don't have to "mess" with them any more.

Chris

73 911 E

[RMR 98]

[QUOTE=burgermeister;5820931]I've got no mods on my car at all. Even stock ride height. So the 'track use' excuse doesn't work for me...

And the outer boots split for me, so heat isn't to blame. Looks like the OP's split started on the inside fold right at the mold line (same as on both of my boots) - if exhaust heat were to blame, seems like the outside tip would be more likely to go - the inside fold is rather shaded.

My split boot (both looked the same)
To be clear, the boots that split on me came with the new axles. I don't have any gripes with the boot kit (yet).QUOTE]

burgermeister,
Did you get the EMPI kit(s) from Pelican? (PN 000-043-301-08-M84)
Last July Pelican did not offer just CV Boots for Carreras/G50 cars, which are different than 915s, they only sold axle assys. This "new" EMPI kit says '85 through '89 with 915 trans. Of course this is out of whack since the G50 started in '87. If not from Pelican, where did you get them?

Thanks,
Bruce

[88911coupe]

I was talking to a friend at work about my CV boots tearing and he said he's seen some sort of kevlar(?) "overboot" used in some offroad ATVs on their rubber CV boots. He rides dirt bikes a lot and comes across these guys on ATVs and they don't want a boot tear out in the boonies to ruin a part while they try to get it back to be repaired. Sounds like it may help out in our situation.

[Wil Ferch]

I kinda don't buy the heat argument either......the split is in the "valley". Let me ask this---> look at the failed CV boot photo. Does the overall *thickness* of the rubber.....on *that* unit.... look a bit "thin" to you, compared to what you might see as Porsche OEM ???

.... or could that just be an optical illusion?

[burgermeister]

burgermeister,
Did you get the EMPI kit(s) from Pelican? (PN 000-043-301-08-M84)
Last July Pelican did not offer just CV Boots for Carreras/G50 cars, which are different than 915s, they only sold axle assys. This "new" EMPI kit says '85 through '89 with 915 trans. Of course this is out of whack since the G50 started in '87. If not from Pelican, where did you get them?

Thanks,
Bruce[/QUOTE]

I got both a GKN & an EMPI kit from Pelican - they had both when I ordered. Replacing the outer boot took some creativity ...

I also have a spare axle now, and I've gotten good enough where I can swap one in about 1.5 hours.

[burgermeister]

Just as a followup, I had my driveline out last fall. Upon careful examination, all but 1 of the remaining GKN axle boots had small rips in them. Not all the way through yet, but definitely there. That's 5/6 within 2 years or 8,000 miles. 3 went within 4,000 miles.

All tears started at the inside corner of the biggest pleat, right at the parting line flash. All the boots had very coarse, large amounts of flash. The boots from the axles that came with the car, as well as the replacement GKN boots I had on hand, had only a very small mount of fine, consistent flash. So it might be a "we paid dongfeng rubber works to build boots to print" issue. I now have EMPI boots everywhere, I'll se how they hold up.

Replacing both boots on the axle is at most a 90 minute job (3 hours with removal / reinstallation, and that's for me, so it ought to be faster for normal people) IF the CV's don't have to be re-packed or disassembled, so it pays to catch them early.

[RMR 98]

burgermeister,
Thanks for the follow up and interesting observation about the crack starting at the mold flash.
I replaced my split boot with an EMPI boot (from Pelican) installed with a vent tube. Also have coated headers now. Racing plans delayed by gearbox problems but will post update after I get back on track.
BTW, I'm carrying a spare EMPI boot - hopefully to ward off the crack demons!

[JP911]

To add to this thread, I just bolted up a pair of new G50 axles (purchased from Pelican) last weekend, did a 2 day DE this weekend, and both of my inboard CV boots have split. I was under the car today checking things over and spotted grease all over the place...I can barely even see my starter in the mess. GKN/lobro really needs to do something about this.

Not sure which road to take: replacement GKN/lobro boots or an aftermarket option.

[DRACO A5OG]

Slightly OT but I had to share my experience and give hope to those dreading the CV boot replacement chore.

Not for nothing but I have replaced the CV boots on my lady's Lexus. It took me less than an hour.

I used a very un-orthodox method of slipping the replacement boot on. It is ridiculously simple. I did not believe it until I did it.

Tools:

Large Long Black Funnel (found on the impulse shelf at a FLAPS)
K&N Filter Spray Oil (anything that is tacky)
(of Course tools needed for removal of wheel, rotor/hub etc...)

Removed torn CV boots and cleaned the CV's thoroughly with no-residue cleaner spray.

I modified the funnel to match the OD of the existing CV, smoothed out all edges. (This was part of the hour spent)

Sprayed oil on the funnel.

Placed the large end on the CV then firmly slipped on the inner boot "pop' it was on then repeated the oil and flipped the outer boot inside out then slipped that on too "pop" . You need to flip the outer one so the when it slips on, you can flip it back so the orientation will face wide part out. Trying to slip the small end over the CV is impossible, unless you have a press tool.

Wiped off the oil and packed with included CV lube, crimped the metal ties.

It was that easy.

It has been 4 months and tight as a bug.

Here is the video I watched in disbelief: http://www.youtube.com/watch?v=F17tFS6ofzU&feature=related