tolsen

Fitting Grease Nipples On Rear Wheel Bearings

31 posts in this topic

Posted (edited) · Report post

The tricky bit is to find a path for the grease to enter bearing internals.

My solution is to apply grease through a grease nipple fitted in the head of the bolt:

DSC02178.jpg

The bolt is only grade 8.8 so rather soft and easy to drill. Have not yet tapped the threads for the nipple as I am having great trouble finding my 1/4" x 28 TPI taps. Radial hole drilled 2 mm diameter. Centre hole drilled 2.5 mm diameter.

The Grease Path:

[*]Through grease nipple fitted in head of bolt.

[*]Passes out of bolt through radial 2 mm hole.

[*]Passes through the spline.

[*]Passes through flat ground on inner part of hub assembly and enters centre of bearing.

DSC02176.jpg

Above photo shows an old bearing where a grease path has been ground on the hub assembly.

Ideally there should be no grease leaking out through the outboard seal as not particularly good for my drum brakes. I am thinking of fitting a stronger garter spring if I can get hold of one. Another alternative is to renew the outboard seal - most likely impossible to source one that will fit. Size of seal is 51.3 x 63 x 5 mm. Third alternative is to wipe off any grease that leaks out inside the drum.

Any suggestions?

Edited by tolsen
Fixed broken image links.

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Every time Tolsen posts a new topic it is always interesting reading.Size of seal is 51.3 x 63 x 5 mm. What if that was Imperial? How close were your measurements? 2.019" x 2.480" x .197"

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My measurements are fairly accurate apart from the thickness which I estimated. Have now worked out a fix. For some obscure reason the seals are fitted opposite to the normal convention. Both are fitted with the inside of the seal facing the elements so the garter springs will corrode gradually loosing pressure on the elastomer seals against rotating surfaces. I shall turn the outboard seal around, thereby it will be energised by grease pressure. The only problem is how to get the seal off without causing any deformation or damage.

Edit:

It turns out the bearing shown in first post of this thread had been cannibalized, i.e. some parts were missing.

Archive photo. Black ring below hub axle forms part of seal labyrinth. I had used this ring and a garter spring (seal compression spring) to rebuild another rear bearing in Sep 08.

DSC01369.jpg

This is the outboard seal that I intended to fit the other way around. Without the black ring mentioned above it does not matter which way it sits. The seal will leak regardless. The black ring adds about 2 mm to the seal diameter.

DSC01370.jpg

DSC02178.jpg

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Grease nipple modification is complete.

Rear bearing completely disassembled. New labyrinth part made out of bronze (see part bottom left) - same size as original:

DSC02183.jpg

Assembled bearing. Grease nipple fitted in centre of bolt:

DSC02190.jpg

Injected lithium EP grease using a standard cartridge grease gun. Very little grease leaked out on outboard side:

DSC02188.jpg

 

DSC02189.jpg

Road testing soon.

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A person also needs to be absolutely sure the grease can't / won't get on the rear brake shoes.

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A person also needs to be absolutely sure the grease can't / won't get on the rear brake shoes.

A wee bit of grease makes no difference. Lots of grease and the drum brakes may last forever. I suggest you check and clean off any excess grease when injecting.The main object of this exercise was to work out a method whereby grease could be injected into the bearing. Reason: Main cause of bearing failure is water entering bearing though inboard side seal.My 2002 Smart with 133K clocked has so far only had one new bearing on rear axle. I rebuilt and regreased rear bearing on the other side using bits from the failed bearing which is the one you can see in the photos. There is no way I may take my Smart to the heavens, but the grease nipples may allow me to drive my Smart without further bearing changes until I have to go.

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Posted (edited) · Report post

I'm always impressed with your ingenious fixes Tolsen! Well Done!What torque value do you recommend for the rear axle bolts for the correct bearing preload?E.B.

Edited by ETHICAL BEEF

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A word of caution: spherical ball bearings get ovalised slightly over time and so when a bearing that has been worn a bit is dismantled and reassembled, the orientation of the ovalised balls can be disturbed, causing difficulties accurately torquing the bearing (they can loosen up quickly) and can suffer early failure as a result. There were some SAE papers on this back in the 1980s...So this modification might be better done on new bearings.

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Mike T is right. Good practise when reassembling used bearings is to spin the wheel while gradually increasing the preload. This will reorientate the balls. Better would be to renew all balls if they are found to be oval as otherwise there will be play in the bearing. Go for grade 10.Specified torque is 3 dNm + 90 angle turn.

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The final version of the grease groove was ground using a superior Lidl "Dremel compatible" tool:

DSC02256.jpg

The U shaped grease groove removes less material compared to grinding a flat groove with an angle grinder. All grinding dust etc must be cleaned off as otherwise the bearing won't last long. Any dirt in the grease path will contaminate the bearing. Drive shaft spline forms part of the grease path and must be cleaned as well.

Bearing assembled and fitted on LHS rear axle:

DSC02257.jpg

Some care need be exercised when injecting grease. More resistance will be felt on the grease pump when bearing is full. From that point only inject grease at a very slow rate to allow excess grease time to leak out.

Fitted new 1.9 mm thick washers (previous washers were 0.9 mm thick) in the top bearing mounting bolts to get rid of the ridiculous overloaded trailer look. Camber will now become - 0.5 degrees assuming that original camber was - 2.0 degrees. Perhaps there will be less uneven wear on the rear tyres?

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Fitted new 1.9 mm thick washers (previous washers were 0.9 mm thick) in the top bearing mounting bolts to get rid of the ridiculous overloaded trailer look. Camber will now become - 0.5 degrees assuming that original camber was - 2.0 degrees. Perhaps there will be less uneven wear on the rear tyres?

Will you need an alignment after doing this?Bil :senile:

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Will you need an alignment after doing this?Bil :senile:

Mr Arctangent tells me there is 0.088 degrees change in angle per 0.10 mm change in washer thickness. Therefore no need to check wheel alignment as my washers are all same thickness and size.

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bilgladstone said:

Will you need an alignment after doing this?

Bil :senile:

DIY tracking measurements.

Tools needed:

1) Measuring tape.

2) Parallel bars.

3) Digital caliper or equivalent capable of measuring within 0.05 mm.

4) Calculator, tables or slide rule capable of doing arctangent calculations.

DSC02261.jpg

Parallel bars arranged at each side of Smart. The bars must be straight. I used two 40 x 40 RHS steel bars. Adjust bars parallel to the car. Measure between bars fore and aft. Aim for max deviation less than 0.5 mm.

DSC02262.jpg

Note that the bars need be positioned at centre of wheel for most accurate result. Rims must be true as otherwise there will be errors.

Measure distances between bar and forward and aft of each rim using the digital caliper. Calculate difference - delta. Repeat for each wheel. Measure distance between measuring points on the rims. In may case 405 mm.

Use arctangent to calculate toe of each wheel:

Toe = arctangent (delta/405)

Result:

Rear left 17 minutes.

Rear right 16 minutes.

Front left 17 minutes.

Front right 11 minutes.

Specification according to Evilution's famous and mostly accurate bible:

Rear up to end of 2002 (my Smart): Total toe 10 +/- 10 minutes.

Rear from 2003: Total toe 20 +/- 12 minutes.

Front: Toe per wheel 14 +/- 5 minutes.

Conclusion:

Front toe is spot on. 17 + 11 = 2 x 14 = 28 minutes.

Rear toe is out but not much. Nearly within spec going by 2003 specification but out by 13 minutes to specification applicable to my Smart.

Next task is to figure out why toe is out on rear axle and how to correct it.

TK guinness.gifdriving.gif

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Kudos for the DIY jobs, TK. You rock the smart-tech world!But DIY alignment is too fuzzy for me. Bar must be perfectly straight. Wheels must be perfectly true. Rear track is wider than front track (at least on my 2005), etc. Not to mention eyesight and calipers, cost of two rigid bars, etc.I'd much rather have a full alignment done by a reliable, professional alignment shop with lasers etc. for $90. Just had mine done for a second time - first following a mild front end crash, latterly after lowering suspension - and very pleased. Worth it to me :dunno:B :senile:

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I am pondering over why my rear suspension is out w.r.t. tracking. Panhard rods or their bushes perhaps? I can cold bend the De Dion tube. Bending it by heat shrinking may also work but there is risk of causing unintentional fire. Cold bending can cause my Smart to become dog tracked. What do you reckon is my best option?

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[just musing here...]I have wondered for some time whether, after high mileage or extended (or high-wear) service life, those bushings might weaken and allow the rear to to wander. The De Dion tube may be wide or narrow, within certain specs, from the factory, but those (what you are calling) Panhard rods should keep the dimensions properly fixed - conditional upon the bushings' designed rigidity being maintained.I haven't really examined the rear suspension - not my area of deep knowledge - but the toe-in/out is adjustable, no?

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Posted (edited) · Report post

They're Watts linkages! A Panhard rod is attached to the axle at one side and to the chassis at the opposite side of the car.I wouldn't mickey around with the toe setting on the rear, it doesn't sound as though it's all that bad.

Edited by Mike T

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I'm not positive, but I don't think it's a pure Watts either, since the centre connector is not articulated. Kind of a fish, flesh-nor-fowl linkage :dunno:... a "Pan-watts"!

Watts: articulated

Posted Image

Panhard: rigid

Posted Image

B :senile:

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You are correct; the B-Class has a proper Watts linkage but the smart does not. But it's definitely not a Panhard rod!

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I've always referred to these rods as Panhard rods but do not rule out that I could be wrong. Their function is to prevent the axle moving from side to side. Panhard rods are also called track rods, which is what you have on the front axle. There is no tracking adjustment on the rear axle of the Smart other than by bending the De Dion tube.

Assistance from a young smart engineer is now called for. I need the force required to pull the De Dion tube to yield, permanently deforming the material so I can get tracking nearer to neutral.

I shall try pulling the De Dion tube together elastically first, loosen each end of the "Panhard" rods and retighten, then release the DD tube and repeat my measurements. An interesting experiment in itself. I look forward to see if this will have any effect on the toe.

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Posted (edited) · Report post

From what I have read, the DeDion tube is under pressure such that you should loop your come-along or winch tightly around the two ends before releasing the end bolts.

FQ101 has a nice page on replacing tired bushings with Powerflex replacements. I would like to do this one day...

Posted Image

US cost is about $140 for the set of 4 link arm bushings: 2 inner + 2 outer.

Oh, and you've seen these adjustable rods, right?

Posted Image

Bil :senile: Edited by bilgladstone

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Yes there is a wee bit of tension in those "Panhard" rods. Slackening off the top bolts where the assembly mounts to the subframe is normally sufficient.

Have spent the whole morning working out force required to permanently deform the De Dion tube. Sussing out the formula was quick but writing it out in MS Word took hours. Here it is:

Forcestress.png

D = De Dion tube outer diameter = 80 mm.

t = De Dion tube thickness = 3 mm.

A = Distance in mm from centre of transverse section of DD tube to point where force F is applied. Max distance is 500 mm unless scaffolding tubes etc are inserted.

F = Applied lateral force to cause DD tube to start to yield or deform.

Sigma (the funny looking letter at RHS of formula) = Yield stress of DD tube assumed to be no higher than 360 kPa.

Example: Force F is applied between the aft ends of the DD tube so A = 450 mm. Calculated force becomes 11.2 kN = 1.2 Tonnes. We shall try soon but stay within the elastic range to start with.

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Adjustment has been done:

DSC02263.jpg

I pulled a wee bit on the De Dion tube. Could not wrap the chain around the end of the DD tube due to interference with Panhard rod brackets so used two short pipes stuck inside and padded with rubber in way of contact with the DD tube. The hydraulic cylinder is good for 2 tons and I guess I was pulling close to 1.5 Tonnes. Released the hydraulic puller and checked distance between ends of DD tube. Kept applying force and checking for a while until happy. Fitted bolts loosely on reassembly, pulled moderately on DD tube and tightened bolts to specified torque.

Measured toe:

Rear left: 7 minutes. Previous reading was 17 minutes.

Rear right: 5 minutes. Previous reading was 16 minutes.

May repeat toe measurements after a few miles of driving. Toe is now within specification (total toe 10 +/- 10 minutes).

Camber:

Rear left: - 40 minutes.

Rear right: - 29 minutes.

Specification for camber is - 2 degrees +/- 30 minutes and 20 minutes max difference between each side. Note that I have added shims in order to reduce camber by 1.5 degree to get rid of the overloaded trailer look and hopefully get less tyre wear.

 

 

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Amazing work! Did you find any deformation of the rod bushes?

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