I have some questions about CV axles.
On front wheel drive cars, the side of the car furthest away from the transmission, often requires a support bearing bracket that gets mounted to the engine due to it’s longer length, this is to support the axle.
This bracket has a bearing in it to allow for rotation to occur. This got me thinking, that during install grease is probably applied to allow for an easy install. That’s the only time this bearing gets lubricated until the axle is removed. Would it be good practice to squirt some grease in there periodically through the bolt on the side (highlighted in yellow) to lubricate the bearing? Could it hurt anything?
With time the grease inside of the joint wears out and doesn’t do as good of a job lubricating the bearing. Eventually the CV axle will need to be replaced as a result. Is it a good idea to put threaded hole on either dust cover and install a zerk fitting? This would allow you to put grease into it without having to completely remove it? You could even install a recessed zerk fitting that doesn’t stick out of the surface of the dust cover so you don’t have to worry about a rock coming up and knocking it off losing all of your grease. Although I don’t think that would even be something to really worry about, because of zerk fittings on lower ball joints etc.? But a recessed zerk fitting would be nice. I mean it’s possible to have a zerk fitting get hit off but I think extremely unlikely. I also think it’s more likely a portion of the fitting would brake off, and not the whole fitting.
The upper part looks like a bracket with no bearing. The axle you show has no bearing on the outer diameter. These do not look to me to be designed to rotate at road speed relative to one another. So, given what I see, no grease is required, the bolt is a retainer to lock something in place.
If you tell us what car you are referring to we might be able to have a more productive discussion as not all cars are the same.
It is a sealed bearing like a wheel bearing, you can’t add grease. Injecting grease through the bolt hole may keep the bracket from rusting to the outer race of the bearing for easier removal.
The grease in the CV joints are good for the life of the car or until the boot tears. The CV joints and boots on my 1996 Dodge have never been replaced.
That bracket mounted to the engine with the bearing is there to prevent torque steer.
Torque steer occurs when two drive axles of different lengths have torque applied to them which then makes the vehicle want to turn
Coming out of the transmission with a straight axle to the bearing so both angled axles are the same length eliminates torque steer.
I know why it is there, but there appears to a missing part not shown… a sealed bearing that is locked into the bracket shown, I’d guess. Maybe part of the jackshaft from trans to axle shaft perhaps? Yoshi didn’t tell us which car he was workIng on.
Yep, here’s a picture of complete jackshaft and axle shaft, with the bearing in question.
If you are asking whether it makes sense from a routine maintenance perspective to periodically lube the CV joints themselves (i.e. inside the rubber boots), I’ve always done that. Only for the outer joints though, on my CV-equipped cars, VW Rabbit, & Corolla. On the Rabbit it was easier to remove the axle and do it on the bench. On the Corolla, easier to leave the axle in place in the transmission, just popping the outer end of the axle out of the hub. I remove the entire CV joint from the axle, clean it of all the old grease, lube the ball bearings, reinstall the CV joint, then more grease, before re-clamping the boot. Oft-times when doing this I discover the boot is near the end of its life, so I replace it too.
A quicker way – I’ve never done this — might be to leave the axle in place on both ends, and just unclamp the boot and clean as much of the old grease out, and put in some new grease, then re-clamp the boot.
I don’t bother with this for the inner CV joint b/c it doesn’t have as big of a task to accomplish, in & out, very little lateral flexing. I’ve never had an inner CV joint fail or otherwise cause problems.
My method may not work on some newer cars if they are designed so the outer CV joint cannot be removed without damaging it.
I think if you asked a pro-mechanic, they’d decline to do this for you, saying its more economical to just replace the entire axle.
My bad. I have a 2005 Camry. I also showed the shorter axle instead of the longer one without the bearing on it.
So in this instance the bearing is already secured to the axle and comes as an assembly. I thought the supporting bracket had a bearing in it, but I now see what you mean. It looked like a pedestal bearing.
How is the bearing circled in red secured to the axle?
So the supporting bracket is just a metal bracket. Does the bearing (that’s attached to the axle) rub against the inside of the bracket at all? In order to act as a support the bracket has to come into contact with some part of the axle, and you have metal rubbing against metal?
I see what you mean. Just like how wheel bearings eventually fail, and other sealed bearings, I figured CV axle bearing would fail with time, even if the boot didn’t get damaged and cut open to allow the grease to come out. Eventually with enough time and mileage, I would expect it to fail even with a sealed boot?
the bearing that is circled is pressed on. the inside of the bearing turns with the axel. the outside of the bearing does not move, it is held by the bracket above. so, no need to lube the inside of the bracket that holds the bearing.
You may be confusing the terminology. The axle-shaft has an outer and inner CV joint, and in your case that support bearing (circled in red above). The joints are each covered by a boots. The outer joint has to flex to quite severe angles to allow the wheels to turn, and therefore needs a set of ball bearings placed in their respective sockets; the inner joint doesn’t use ball bearings. Instead there’s a three arm gadget configured on one side that slides in an axial direction along three corresponding channels on the other side. It’s primary purpose is to allow the axle to lengthen and shorten as the wheel goes over bumps. Sort of the same idea, function-wise, as a 2 part splined driveshaft in rear wheel drive vehicles.
Hey Thanks. I see what you mean about the outer race not rotating in the holder, so there is no metal rubbing against metal un-lubricated.
Thanks for clarifying the terminology.
I see that periodically regreasing a CV axle has some benefits. It seems like a lot of work to remove it from the vehicle and disassemble it every time you want to degrease it. I was thinking of possibly adding a Zerk fitting to the housing.
Disassemble it once when it’s brand new, and then use a thread tap to get the proper hole to install a Zerk fitting. Then you can pump grease in without removing it from the vehicle. I guess the extra grease would come out through the Zerk fitting once it’s full or from beneath the clamps on the boots. If you used grease that was colored like red for example, you could pump grease in there and watch the old grease come out until you started seeing red grease come out.
I was also thinking, does it make sense to paint a CV axle? My original one has rusted. It’s just bare metal. I find it strange that they come from the factory bare and unpainted. I even know people who have a brand new car, just one winter in the rust belt, and it rusted. Not that the rust really matters, but seems like a no brainer to paint it to avoid the rust. Unless I’m unsure if there’s a reason they come unpainted? I can’t think of one.
I expect the problem w/the zerk fitting idea is that the old grease doesn’t really come out of the boot as long as the boot remains intact. The problem is that as the axle spins, the grease tends to get thrown away from where it is supposed to be ; i.e surrounding the ball bearings on the outer joint. What’s needed to rejuvenate the lube isn’t more grease inside the boot so much, as grease repositioned to where it will do its best job. If you got too much grease inside the boot the centrifugal forces of the extra mass might cause the boot to pop loose.
You seems like a scientific type of thinker, so one idea, try the improvised zerk on one side, not on the other (for an experimental control). Tell us what you discover.
Overthinking yet again. There is no benefit to periodically regreasing a CV joint. This only needs to be done if the boot is compromised. Then the joint needs to be taken apart, cleaned, regreased, and a new boot installed. Obviously, this can’t be done without removing the axle. Usually, by the time you realize the boot is damaged, so is the joint so it needs to be replaced anyway.
Over thinking again , just like most of Yoshi’s threads .
Just a cost cutting deal. Most people don’t look under there, and the rust doesn’t affect anything other than the appearance.
Not sure the housing is hollow. Might can find enough room on part of it up near the boot to install zerk, but it’s going to be a pretty thick piece to drill into.
The boot should be water tight. I don’t think the old grease is going to come out at all. You’ll probably wind up with a CV boot bloated with grease. May even cause an imbalance and vibration.
Most suspension and drive parts are sealed and non serviceable nowadays (u-joints, ball joints, etc). They seem to last pretty well without getting greased, though.
another thing to consider is the zerk fitting can hit a suspension part while spinning and can snap off.
The CV joints have a specific amount of grease in them. They are sealed so no dirt or other contaminates get in to the grease (until the boot tears). There is not a lot of friction inside the CV Joint so the grease does not get very hot. Since it doesn’t get hot, it does not break down.
There is no need to add grease and if you do anyway, you could damage the CV joint.