Replacing Rear Arm Bearings

Frequently asked technical questions and common modifications/improvements
Brian
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Post by Brian » Tue Jan 11, 2011 10:03 am

Vanny Wrote:
First time i've seen my coloured in pictures get reused. I love the Interwebs.

Yes, very good picture that, actually indicates the shim location.

Don't forget folks, 3/4 fill the void between the inner metal tube and the plastic outer tube with thick oil, or oil/greese mix (Area shown white on the picture).

That done, the bearings will last a very very long time.

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Vanny
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Post by Vanny » Tue Jan 11, 2011 5:08 pm

Why only 3 quarter full? I always go for as much as i can, less one half finger for expansion. I can't see any reason not to stuff it though really, if the grease escapes then it will be through the bearings and voila, job done.

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Post by Defender110 » Tue Jan 11, 2011 9:59 pm

I drilled, tapped and put grease nipples in mine on the TZD
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Vanny
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Post by Vanny » Tue Jan 11, 2011 10:45 pm

And either didn't fit the plastic tube so now the bearings are filling rust from the void in the arm, left the plastic tube in and are now filling the void with oil which does no good what so ever, or drilled and tapped the length of the rather large and serious pivot bolt in the hope that it wont decide to rotate to the 'death position', snap and fall out.

Unless you've come up with another option on how to fit the nipple AND get the oil into the plastic pipe?

Frankly I think the latest zero maintenance sealed bearings are the way to go, especially as they don't rotate (very much).

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Post by Defender110 » Tue Jan 11, 2011 11:14 pm

Or drilled and tapped outer shell, measured the hieght to nylon tube, drilled pilot hole into nylon tube, measured and cut the required length of small diameter nylon tube, inserted this up over pilot hole and locked it up with the grease nipple. filled inside of nylon tube till grease just started showing at the seal! :wink:
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1993 Land Rover Discovery 300tdi 3 door - in need of TLC

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Vanny
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Post by Vanny » Wed Jan 12, 2011 2:00 pm

Cool, have you any pics?

How do you make sure there is a good fitment on the filler tube to main tube? Big wall thickness? What happens in the extremely hot summers we have when the greese goes thin?

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Post by Defender110 » Wed Jan 12, 2011 3:22 pm

No pictures of this one but I might do my TGD when I get some spare time and take some then. I did this as a preventative measure in situ on the ramps the bearings hadn't gone and it has been done in the hope they will now last.
The filler tube was just HGV small bore nylon air pipe that was very sturdy in the small length required, getting the right length was just a little trial and error using the grease nipple for adjustment.
As for the grease getting thin in our long hot summers it hasn't been an issue and the grease isn't anywhere the original grease wasn't. IMHO oppinion from those I have done the rear bearings only fail because of water ingress through the seals and the theory is that now they are full of grease there will be no room for water ingress.
I have just serviced/mot'd it over Christmas and all was dry under there and when I connected my grease gun excess grease wash pushed past the seals telling me the tubes are still full.
In summary it was very simple to do (on a vehicle lift), I already have all the tools / sundries required, it didn't cost me anything so I had nothing to loose by trying.
Will it stop the bearings collapsing? Only time will tell.
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1997 Mercedes C230 W202 - daily driver.
2010 BMW X1 SE 2.0D Auto - Her indoors daily driver.
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1993 Land Rover Discovery 300tdi 3 door - in need of TLC

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Vanny
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Post by Vanny » Wed Jan 12, 2011 11:01 pm

From experience i reckon the bearing collapse because of initial wear because of water ingress, exagerated by heavy load only only three or four rollers. I've never had the bearings go on any car i have done the replacment on, but i'm quite sure that is only down to the miles travelled rather than some special technique. The most recorded miles on a set of bearings i've fitted was around 40k before the car went AWOL, well the scrappers. And thets just through packing with decent grease.

There is definately something to be said for a well lubed machine, all the best machines have lubrication points!

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Post by toddao » Thu Aug 04, 2011 9:30 am

Picking up this thread again about fitting a grease nipple to lubricate the bearings.
I found this old post on Aussie Frogs by our mate Alan S which seems to offer a solution as to how and where to fit the nipple. Problem is, the pics have gone so I can't quite understand where the grease exits once the bolt head has been tapped and fitted with a nipple. Actually I can't really get my head round it at all! Any thoughts? ( or rough diagrams)

http://www.aussiefrogs.com/forum/showthread.php?t=17709
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Post by JayW » Thu Aug 04, 2011 6:14 pm

I fitted nipples to my Valver about 5 years ago, I remember a lot of headscratching trying to work out where to put them so i'll see if i still have photos.

IIRC i not only had to modify the plastic sleeve to that the grease could penetrate all areas, but also had to "stop-up" the void in the arm itself (otherwise it would have taken a neverending quantity of grease.

It was however successful, though it should be noted that due to the bearing seal there won't be any grease oozing out the sides, just the seals bulging (and tightening) inside the mounting.
I have zero patience for your tedium.

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Post by toddao » Thu Aug 04, 2011 8:03 pm

That would be helpful if you have any pics. Yes that 'void' in the arm is a bit of a grease sink if not rightly done.
What Alan S was saying - if I've understood at all - that the later modification for the grease nipple concept was drilling in through the head of the bolt so the grease lubricates only the bearings.But I can't see where the grease exits, unless the bolt itself is then drilled at a right angle to the tap?
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Vanny
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Post by Vanny » Wed Aug 10, 2011 7:10 pm

This is the second theoretical solution from AlanS i believe, the first to put a fill point further back in the arm and let it fill the void. But this would never allow oil near the bearings as they are effectively sealed inside the inner plastic tube.

This bolt idea is also completely flawed, but AlanS would never accept any discussion on the matter.

This method simply lubricates the surface between the bolt and the steel tube that is between the bearings. No grease/oil would ever come in contact with the bearings! Its also a bloody stupid idea to start drilling holes in the bolt that holds the whole rear suspension together. I've never done the math, but car manufacturers don't spec a 16mm shank when 12mm will do!

A later revision, i forget who it came from, was to put the nipple in at an angle, drilling a hole just above the bearing and into the tube. Beyond being a total pig to do, this would mean drilling into the bearing mating surface, and given how much damage occurs to be bottom face when the bearing dries, this is a no no.

The only decent and workable (and frankly easy) solution is to put a nipple on the arm above the inner plastic tube, then drill a hole through the plastic tube, and most importantly, link the nipple to the hole in the tube with a small length of hard nylon (or similar) tube.


I'll admit it is a bit of a pet hate of mine this topic. Quite frankly the best way to extend the life is to simply put them together correctly in the first place, which means putting the correct shims in and allowing the bearings to rotate, this way it isn't 4 rollers doing all the work for 10 years!


Failing that, SKF do a fantastic range of completely sealed bearings which should see the job last 30+ years!

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Post by toddao » Wed Aug 10, 2011 8:45 pm

Vanny wrote
I'll admit it is a bit of a pet hate of mine this topic.
:lol:

Yes, it's just about been flogged to death.. so, lets flog it some more!

Good thoughts on the subject though.The archive is stocked up for the benefit of future masochists!
I'm just about to do the bearings on my 16v but I probably won't be scientifically applying grease nipples as I doubt I'll ever do enough KMs in it to wear out even the cheapo 'Mapco' ones I'm fitting!
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Jaba
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Post by Jaba » Mon Aug 15, 2011 6:39 pm

Never seen the point of fitting a grease nipple(s) when you can just pack the gap between the tube and the black plastic shroud with some runny grease and the bearings will then be lubricated for life.

As a fan of AlanS's I was quite happy for him to go to far more trouble than I would if he wanted to do so. I seem to recall he nippled up a CX first which was an easier job. Do they have aluminium arms ?
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Post by MULLEY » Mon Aug 15, 2011 10:23 pm

Vanny, those sealed bearings sound interesting, have you fitted those to rear arms & which one's would be ideal candidates & would other modifications be required? I like the idea of 30 year arms :D
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