Why did my new cv boot split?
 

After 3-1/2 days of Club Race & DE last August & September, I recently discovered that I have a split CV boot on the driver's side, inboard.

The full story: Car is a 1988 Carrera dedicated track car. I ran stock exhaust for ~60 days of CR & DE over 3 years and then installed European Racing Headers last July. After 1 afternoon track day I had 2 split CV boots - Left inboard and Right outboard. The day was hot (98 degrees) and the boots were old (145K miles) so I bought and installed new GKN axle/CV assemblies from Pelican last July. Then I drove 2-1/2 day CR and 1 day DE in August & Sept before parking the car for the winter. Started work on it last month and discovered the Left inboard boot had split, apparently during my last driving session or two because grease was all over (cleaned up before the photo).

Has anyone experienced bad GKN CV Boots?
Has anyone had problems with boots after installing headers?


http://forums.pelicanparts.com/uploa...1296327059.jpg
http://forums.pelicanparts.com/uploa...1296327081.jpg

Some suggest that when lifting the car with clamps on the small part of the boot it could cause tearing.

Some recommend not using the clamps on the small end.


http://forums.pelicanparts.com/porsche-911-technical-forum/210117-cv-joint-boot-clamps.html

http://forums.pelicanparts.com/porsche-911-technical-forum/395604-cv-boot-clamps-sc.html

Odd... I was prepared to say that the "Meyle" crap that's out there doesn't seem to have enough anti-ozoneate mixed into the rubber compound but I've never experienced that with GKN/Loebro products.

Also….
The boot is very close to the outer radius-of-bend of the exhaust header pipe.
The outer radius of a bend is the hottest part of the pipe.
With a heat exchanger, there is little radiant heat directed to the boot.
Without the intervening metal, I suspect the temperature of the pipe could be in the range orange-yellow 2800-3200°K.

http://forums.pelicanparts.com/uploa...1296331166.jpg
2800-3200°K = 2527-2927°C, 4580-5300°F
1800°K = 1527°C, 2781°F
HOT


Depending on the air flow, that could ‘cook’ the boot.

I would clamp a small ‘shield’ between the outside radius of the pipe and the boot.
You might consider some other radiant heat and hot air deflectors.

Best,
Grady

The best solution I've found is coating the headers with a ceramic-metallic thermal barrier material as that makes a very noticable difference in radiated heat.

We have them done both inside and outside to contain the heat inside the pipes.

Where did you get them?

Steve's right - the radiated heat difference is absolutely stunning. The temperature difference is so dramatic that you can do quick finger touches (on a street car) while the engine is running (even after it's been on a long drive). There is no way on the planet that you could do that without coated headers. The smell of your frying skin and your piercing girlish shrieks would inform everyone around of the difference - LOL!

Besides, it looks very nice.

angela

Thank you all very much for your thoughts.
I'm going to look into coatings.

Prost!
Bruce

I bought them from Pelican.

I would give Scott Pelican Parts Technical BBS - View Profile: Scott at Pelican Parts
a ‘heads up’.
It is this kind of feedback that keeps Pelican the best.

Best,
Grady

Good idea Grady. Will do.
Thanks,
Bruce

It's not a pelican parts issue

I have issue with same design CV's on my car over the years and i don't clamp the small end

it seems as soon as i put the car up on my lift the cv may split after it's 1 or 2 years old.. and it's not my daily ride. The small end does not ride up past the axle lip when lifted and I've been tempted to push the rubber past the lip before lifting but have never done it. It happened once after being jacked up out west and the only saving grace was i didn't lose and grease due to the grease I use sticks like glue. Granted the car never saw over 90 mph on the next 5k+ miles ride home

I've had 2 of those happen on my 88 last year, both on the outboard boot, 1 on each side. Both axles were replaced in 2009, so the parts were approx. 1 year old, 5 to 7K miles. I think GKN used a batch of crap boots, but that's just my opinion. I sent GKN a complaint, and was told to send the afflicted boots back to the place where I bought the axles (Pelican). Seeing as how shipping the parts back ends up the same price as a replacement boot kit, and doesn't actually get me a replacement boot kit, I just ordered the boot kits ...

At least the inner boot is somewhat easier to replace!

I have had very good results with generic one size can be trimmed to fit all boots. I used to get them from NAPA, but last time I checked there they were no longer carried. So I used a mail order place (JC is first initial, W is last) which had them. To use them you need the style of CV stamped steel end piece to which the boot rubber is attached by a clamp.

I don't know just how one would convert to this style, as the ones I have are many years old. They are not the kind where the CV end of the rubber is rolled into the sheet metal. But on looking again at Bruce's photos, I see he has just the right kind for this. So I'd for sure use these generic ones to replace the busted ones. Much less expensive.

I have taken to using a Carroll Smith idea for the small end of the boot: stick a small plastic tube (snipped from a used up brake clean aerosol can) under the lip, and tie wrap it all. The idea is to allow the air pressure changes as the boot expands and contracts to pass through the tube, so basically it doesn't exist. I see Bruce used the steel clamps on the small ends too. I don't have an opinion on that causing extra strain on the rubber, but there really is no reason to have that end so tightly clamped. Perhaps if yhou plan to ford streams that deep?

I've run the standard inexpensive brand of race headers (not Georges) for years with no effect I could see on boot life (which has been pretty good), and I think they come fairly close to things. So I am a bit dubious about the heat theory. But of course it could be a factor in premature boot failure.

Walt (in transit at Paducah, KY)

Excellent! It looks like generic boots with vent tubes, coated headers and a heat shield all together should improve the life of my boots greatly.
Thanks again to all.
(Walt, I'll try to keep it out of the water!)

Prost!
Bruce

I'm wondering if there's something the boots can be regularly treated/maintained with to extend their life (e.g. rubber/vinyl conditioner)?

If I have to re-do my CV's again because of a split boot, I'm gonna kill someone (mainly myself!).

RMR,
I showed this thread to the supplier who provides us with the GKN boots. He said that the boots are good for stock use, but your modified car and track use is probably more than they can handle. Fortunately, you have some of the top guys on this forum suggesting solutions. Good luck!

- Scott

I see no other mods besides headers. Right? I mean if the trans is moved up and the angle on the CV is odd or there is a mod that could cause this?

Just because it's on the track doesn't mean that stock CV boots should be failing. Porsche has the rep of being able to go from the street to track and back to street with minimal mods. The answer from GKN isn't very satisfactory.

Had the same exact thing happen to the inner joint of both of my new GKN driveshafts last year. I have B&B heat exchangers, which have a significant amount of exposed exhaust piping. The EMPI replacements boots from our host seem much more substantial...

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).
http://forums.pelicanparts.com/uploa...1296600966.jpg