When to replace a cv joint?


#1

I took my 03 Legacy to the dealership for a check-up and found out I have a torn front inner CV boot. I’m doing the work myself, but this isn’t an issue I’ve encountered before. The boot has a complete tear around the entire circumference, and though I haven’t disassembled it, yet, the fact that it’s totally disconnected leads me to believe that the joint has likely suffered damage. How would you assess if it needs to be replaced, or does the condition of the boot just point to the fact that it needs to be replaced?


#2

There’s no real way other than noise to tell if damage has occurred. By the time a CV joint becomes dry and damaged enough to feel play in it, it’s already become noisy. Because the boot is torn does not automatically mean that it’s bad. It depends largely on how long it’s been torn and its driving environment.

Replacing a CV joint basically means replacing the entire half-shaft. They aren’t designed to be field serviceable. There are “split boots” on the market, and they might be worth trying to replace a torn boot on a CV joint that’s still quiet, but I’ve never used one and have no idea how good they are… or aren’t. Perhaps others here are more familiar with them.


#3

I have always thought CV joints could be rebuilt, I am just not good enough to do it , and replacing the axle is much easier and not terribly expensive.

Since it is an 03 Subaru, I would drive it until it makes noise. It could have an expensive failure somewhere else first.


#4

Agreed 100%.
I watched videos once on rebuilding CV joints, as a learning exercise, and IMHO it really isn’t a job that can be done by the average DIYer. I might try it, just as a learning experience, but I’d have more faith in a good rebuilt half-shaft than I would in my own rebuilding of a CV joint. Rebuilding companies have good, properly calibrated equipment, standards to check the parts by, a proper environment to rebuild the joints in, and the procedures, standards, and expertise necessary. Everything needs to be clean, inspected for cratering and other problems, within spec, and properly greased when the job is done.


#5

Thanks the_same_mountainbik, you’ve kind of confirmed one of my suspicions- it’s not making nose and I don’t feel a lot of vibration, so my preference would to not fix what ain’t broke.

I’ve seen three split boots, two domestic and one made by an Italian company, but there aren’t enough reviews to assess whether the positive reviews are just the parts manufacturer/wholesalers putting in a good word for their wares.


#6

I mentioned this situation to my cousin earlier, and he made a suggestion which seems too crazy to possibly work. But just maybe there’s something to it?

In essence:

“Your problem is that you’ve got a leak. What you need is a band aid. Get some grease and pack it back in there. Get saran wrap, or shrink wrap, or any kind of plastic film, and wrap it over the top of the boot. Get a hair dryer and heat it, it’ll shrink and act as a seal. It’s not going to fix it, but it will keep dirt out, and slow the loss of grease.”

This won’t work, will it?


#7

The wrong stuff might just catch fire. There should be enough heat for that. Having the boot changed isn’t that expensive.


#8

When a vehicle comes in with a torn CV boot I replace only the boots on that axle unless it is apparent the joint has been leaking for some time. My customers have their vehicles inspected every 6 months so there is not a great amount of time the boot could have been torn. Driving in winter slop with a torn boot can ruin a joint so driving conditions are a factor. The condition of the joints can be evaluated by driving the vehicle.


#9

I have used the split boots on a couple occasions; for a few $ and an afternoon of cussing and fidgeting it will be better than before. They come with the proper grease usually. And, if you have other front end problems down the road, it can be replaced then.


#10

The car has some age on it and I assume a bunch of miles. You would be best off to replace the halfshaft.

HOWEVER. If you want to really penny pinch you can try this seeing as how it’s the inner joint.
Remove the joint housing from the shaft. Remove the snap ring and inner race/balls from the shaft. Slide a new boot onto the shaft.

Diassemble the inner race/balls and flip the inner race so it’s pointing in the opposite direction. Reinstall the balls and cage. Stick everything back together. This can buy you time on a worn shaft.

What is does is that it moves the contact point on the inner race slightly and provides (just barely) a fresher surface for the balls to rotate on; essentially tightening the joint up.

If it were me I’d replace the shaft but there’s the Miser Option if you care to use it. Hope that helps and nope, not feasible on the outers.


#11

Nevada, I’m not sure I can agree. I’ve very rarely seen someone doing a safety inspection move the boots to look for tears, and the tears are often in the inward convolutions of the boot where they’re rarely apparent without spreading the boot. I do agree with the rest of the post, but I’m not so sure of this point.


#12

How about you remove the axleshaft, replace the boot(s) and don’t even bother flipping the race

That’s what I do as soon as I see torn boots on my personal vehicles

So far, so good

I’d rather throw boots at a factory axleshaft, which is still quiet, versus driving it until it DOES make noise, at which point you’re going to take your chances on a new/rebuilt axleshaft of possibly questionable quality

I’ve even found boot kits for around $5 a pop, including the clamps and grease. How’s that for the Miser Option :smirk:


#13

When someone comes into the shop with a split CV-joint boot, I tell them, drive it until the CV-joint makes noise while cornering where it’s bothersome. Then bring it back and I’ll install a remanufactured half shaft.

Cheapest way to go. And I’ve never had a come-back in 30 years installing CarQuest remanufactured half shafts.

Tester


#14

I agree 110%. :nerd: