How do I add grease into an inner tie rod?

[YoshiMoshi]

TL;DR Summary

How do I get grease into an inner tie rod?

I know inner tie rods come pre-greased, and should be good for a very long time. But I was hoping to add grease into mine every now and then to extend their life. I noticed that some (but not all) inner tie rods have a little hole on the side where a wrench can be put on.

I was thinking at first that the hole is how grease is injected into the ball joint at the factory. However after getting this part, it is clear that this is not the case.

There's a hole in the stud (for what purpose I do not know) and you can look through it and see the hole from the first picture, meaning that the two are connected together, sort of like a giant "L" shape, that goes no where, and seems to have no apparent purpose as far as I can see.

So I have no idea, what is the purpose of these holes?

I was thinking that maybe I could stick a drill bit inside of the rod with a hole in it (green X in the picture below) and drill a hole through the metal at the location of the red X. Eventually I would get into the ball joint area. I could then block of the hole in the stud with a plug, and put a zerk fitting where the other hole is (orange arrow)

Has anyone ever tried to do something like this before, to add grease into an inner tie rod? I find it really strange, that there's no provision for adding grease. With the rest of the metal housing being mostly round, there's not really another good spot to install a zerk fitting. Is my only option to really occasional remove the boot, and use my hands to manually force grease into the ball area?

How do they add grease at the factory? I tried searching of a packer tool for inner tie rods. Some sort of tool that grips onto the inner tie rod to create a closed container, and as you pump grease in it forces it's way through. Kind of like a bearing packer tool. But there appears to be no "inner tie rod grease packer".

Thanks for the help!

Also does anyone know of any videos or pictures, showing the insides of an inner tie rod? I have never seen one cut open before. Regular ball joints, I have though.

 

[Baluncore]

I would expect the inner tie-rod end to be protected, inside the rubber boot, on the end of the steering rack. That grease should last until after the rubber boot fails, when water and dirt may be introduced. Until then, only a small amount of steering rack lubricant fluid should be present inside the boot.

If you attempt to grease the inner tie-rod end, you will have to remove the rubber boot, and will then introduce dirt into the joint with the grease.

There is less angular movement at the inner end of the tie-rod than the outer, so it should displace the grease and wear only very slowly, until the boot fails.

By all means grease the outer tie-rod end that is more accessible and has greater movement. The elbow of the outer tie-rod ball joint makes it possible to introduce grease through an external grease fitting that is not covered by a rubber boot.

The inner tie-rod end is usually assembled in a press, so there is no easy way to disassemble the joint, to drill and thread it for an external grease fitting, which would then project, to foul and damage the protective rubber boot.

So I have no idea, what is the purpose of these holes?

When you turn the steering, the boot volume on one side increases, while on the other side, the volume decreases. That 'L' hole communicates through the centre of the rack with the other side, so air pressure can equilibrate, and the boots are not blown off. The volume of the steering rack chamber has lip seals at both ends to retain the fluid, so air cannot be allowed to flow that way, since it would push fluid out through those seals, into the rubber boot.

 

[Baluncore]

How do they add grease at the factory?

Or, how do they manufacture a pre-greased inner tie-rod end?

First, notice how the outer end of the housing has been pressed to close around the exposed end of the ball. I circumcised a used joint in a lathe, to see how it was assembled inside. The housing material is an unusual steel, carefully chosen to be malleable and is very easily machined. The housing wall was thicker than I expected, maybe that is to compensate for the malleability during assembly and operation.

The polished ball on the inner end of the rod is surrounded by a plastic bearing material, moulded as two separate parts. There is a plastic cup that sits deep in the housing, and a plastic barrel section, (spherical inner, cylindrical outer), that slides down the rod to slip over and surround the ball. It is greased as it is assembled and only then slides into the cylindrical bore of the housing. The two plastic parts fit well together around the ball without any gap.

The housing is then placed in an axial press that closes the rounded end with a die, capturing the ball in the then tightly compressed plastic bushing. There are small channels on the outside of the plastic bushings, that allow any excess grease to escape during assembly.

 

[Nik_2213]

FWIW, is that notch near the flat for a 'Hook Wrench' ??

 

[Baluncore]

FWIW, is that notch near the flat for a 'Hook Wrench' ??

The two flats are used to grip the tie-rod end.
The round hole is the 'L' shaped air vent through the threaded connection with the rack.

 

[sophiecentaur]

If there's no grease nipple, perhaps they don't expect you to need new grease. Isn't all that stuff 'sealed for life' these days? I heard that more bearings are spoiled by pumping grease in and bursting the seals.

And how much money can you save by DIY?

 

[Nik_2213]

"...perhaps they don't expect you to need new grease."
Yes, 'sealed for life'.
I suppose it is cost-effective at this scale. Unlike 'bigger' plant, where seals may be economically removed and replaced, wonky joints, bearings etc re-machined to 'good as new'...

Disclosure: I, too, gawp at those videos of wondrous work by the 'Cutting Edge Australia' machine-shop.

FWIW, I still wish my school had taught formal 'work-shop' skills-- Wood-work, metal turning etc etc.
And, yes, cooking.
Instead, they strove for supremacy on the sports field, while incrementing their Oxbridge count.
Took them until the last month before I went off to local Uni to accidentally discover I'd a rare talent for tech-drawing. Years too late to affect my 'Further Education' arc, it earned me a belated apology from the Arts department...

 

[sophiecentaur]

Unfortunately there is no ‘one size fits all’ possible school curriculum. When there was selection at 11+, there was a split in what was taught for Grammar kids and Secondary Modern kids. Unfortunately there was no money for skills and vocational subjects in sec mod. The result was to produce kids leaving sec mod school with a poor experience of the whole education system. Governments shrugged it off by blaming the school leavers.
Comprehensive education was given at rock bottom prices which meant (still) no money for practical subjects. Then University for All was the slogan. The Degree was often a nonsense term.

 

[Nik_2213]

Sadly, skills and vocational subjects seemed beneath the dignity of my Grammar school...
{ Shrug... }

 

[YoshiMoshi]

I would expect the inner tie-rod end to be protected, inside the rubber boot, on the end of the steering rack. That grease should last until after the rubber boot fails, when water and dirt may be introduced. Until then, only a small amount of steering rack lubricant fluid should be present inside the boot.

If you attempt to grease the inner tie-rod end, you will have to remove the rubber boot, and will then introduce dirt into the joint with the grease.

There is less angular movement at the inner end of the tie-rod than the outer, so it should displace the grease and wear only very slowly, until the boot fails.

By all means grease the outer tie-rod end that is more accessible and has greater movement. The elbow of the outer tie-rod ball joint makes it possible to introduce grease through an external grease fitting that is not covered by a rubber boot.

The inner tie-rod end is usually assembled in a press, so there is no easy way to disassemble the joint, to drill and thread it for an external grease fitting, which would then project, to foul and damage the protective rubber boot.


When you turn the steering, the boot volume on one side increases, while on the other side, the volume decreases. That 'L' hole communicates through the centre of the rack with the other side, so air pressure can equilibrate, and the boots are not blown off. The volume of the steering rack chamber has lip seals at both ends to retain the fluid, so air cannot be allowed to flow that way, since it would push fluid out through those seals, into the rubber boot.

Very interesting! about the left hand side and right hand side being connected together via the vent hole. It makes sense to do it this way, to create an equilibrium.

Also I was wondering

The blue area of the rack and pinion, is always dry, while the purple side is filled with power steering fluid (or ATF depending on the car)? So the blue side it just plain metal on metal gears rubbing up against each other, with whatever oil or grease was applied from the factory, and after several years, it's just metal on metal?

 

[Baluncore]

The blue area of the rack and pinion, is always dry, while the purple side is filled with power steering fluid (or ATF depending on the car)?

That is surely NOT the case.
What make, model, and year, has that dry arrangement.

 

[YoshiMoshi]

That is surely NOT the case.
What make, model, and year, has that dry arrangement.

My bad for late reply. 2005 Camry.

This was from the car, with the old inner tie rod which was extremely worn out, but I can see the teeth of the rack and pinion, it's not in fluid at all, and appears to be grease on it (but it might just been grease seepage from worn out inner ball joint.

Looking at the service information, very interesting indeed! From this it looks like the side of the rack with the teeth is supposed to have grease on it, and there is an o-ring, and piston ring to create a seal. It's like the side of the rack with the teeth, the teeth part is not exposed to PS fluid (which in this case the service information says to use ATF.

I've never heard of someone greasing their power steering rack as preventive maintenance. But it seems like I have 20 year old grease on my rack. There's still some there, just well after 20 years, probably good be regreased? I wonder if it can be over-greased. Is the point of this grease in this application to prevent rusting, or is for metal on metal wear prevention, or I guess even both?

 

[YoshiMoshi]

If anyone is interested. The reason for the delay, I tried this experiment myself. Took an aftermarket inner tie rod, $20 or so, so I figured I would experiment. I drilled a hole in the inner tie rod. The housing is very thick indeed! I either drilled to far up into the housing and didn't penetrate into the chamber that holds the ball joint, or I drilled it unknowingly. The one I had seemed to have a metal baring in the ball joint chamber, didn't see any white plastic, or perhaps I just didn't penetrate the chamber. Regardless I tapped the hole and tried to add grease, but no grease came out of the inner tie rod. So it might be like others said, the clearance between the ball and it's bearing is so tight, that even grease can't get in-between it. Very interesting indeed!

I've drilled holes into inner tie rods before, and added a zerk, worked well. Tried to do this with an inner tie rod as an experiment, and it doesn't seem possible, or very difficult.