10 Mar 2010

Longstaff axle removal.


Let us assume that you want to dismantle the axle components from a journal bearing, Longstaff, OWD conversion set, or trike, to check the condition of the bearings:

Only a few simple tools are required: You will need a couple of Allen keys: One each of 5mm and 2.5mm. It will be safer and much easier to have a pair of ordinary circlip pliers. i.e. those where the jaws press inwards when you press the handles of the pliers together.  A plastic or hard rubber hammer is also useful. Or just use a block of wood to protect the axle ends against damage from an ordinary hammer. This usually requires three or four hands. While a plastic hammer needs only one.

One grub screw and an outer bearing housing circlip are show from below.

Four small grub screws hold the journal bearings gently into the tubular housings from underneath. They must be loosened  before the journal bearings will come out. (or even better: remove the screws completely and store them somewhere safe like a small jar) There should be four screws in the picture but one was already missing. (luckily I found it on the floor) Do not over-tighten these screws later on when you reassemble the axle. Or the bearings may go oval and be permanently damaged! 

Don't work over gravel or long grass or you will almost certainly lose these tiny screws!

The road wheels must be removed next. If you just undo their holding screws then Longstaff wheels are self-extracting from their axles. Now the big, spring circlips can be removed from their grooves in the outer bearing housings. Luckily there are no clips on the inner bearing housings or they would be rather hard to reach!  You will need a pair of circlip pliers to remove the circlips easily and safely. I couldn't find mine and had to make do with long nose pliers. Not a good idea because the jaws do not come together parallel to each other as they do with proper circlip pliers. (this is the secret to easy circlip removal)  There is a great risk of pinching your fingers when using long nosed pliers. Leather gloves may be a good idea if you are reduced to using "alternative" pliers.

After a struggle I managed to press the ends of the circlips together just enough to get a screwdriver behind the circlip and gently ease each of them out. 

Warning:Circlips like to fly dangerously when released unless you use the correct circlip pliers. Even so you should always protect your eyes or cover the circlip with a rag to stop it flying away and becoming lost.  

Circlip pliers are the correct tools for the job and those shown are very inexpensive at about £3 (equiv) each. The bent nose model is slightly easier  to use because the jaws approach each other parallel to the forces required to compress the outward tension in the circlip. The straight jawed model could be much better manufactured to make the jaws parallel to each other in normal use. The hinge area would need to be made wider and the jaws turned inwards like professional quality, circlip pliers. As one's use of such pliers is likely to be very limited indeed either of these cheaper models will do at a pinch.

The only thing holding the non-driven, right side axle in place now is friction. Fortunately all the bearings on their shafts were just push fits. The bearings in their axle housings were only a little more difficult.

I decided the easiest way to get the axle out was to insert a screw into the wheel holding thread in the outer end of the axle. I then placed a claw hammer over the screw head as if it were a large nail. Then I used a plastic hammer to pull the axle and outer bearing with gentle blows against the face of the hammer head holding the screw. This sounds complicated but took only seconds before I had the axle and outer bearing free.

The outer bearing could now be slid off the axle. Then the bare axle reversed and used as a punch to push out the inner bearing with gentle taps from the plastic hammer. Don't ruin the face of the axle end by striking it directly with a steel hammer! Nor damage the bearings by hitting them hard.  Again the bearing came out without much effort. The parts were then cleaned up of excess grease with newspaper followed by wiping with a clean, dry cloth. Don't use a solvent on sealed journal bearings as it  may go inside easily enough but never come out again. Bearings prefer oil or grease as a lubricant rather than a solvent. Sealed bearings are not easy to re-lubricate efficiently by the amateur. A vacuum pump and bell jar are recommended by the only website with any advice on this subject. 

Here the Longstaff sprocket carrier can be seen. The driven axle is the longer one.

The bearings themselves showed signs of surface rusting in places but were otherwise in reasonable condition. Certainly good enough to continue without replacement. Spinning them with a finger through the centre will soon tell you if the bearings are worn out or running rough.There is a surprising amount of drag from the plastic seals on these bearings. Since all were equal in their resistance to rotation this must be fairly normal. It certainly explains the feeling of much lower rolling resistance with the Higgins.  

Sprocket block adapter fixing bolt, washer and an inner axle bearing.

Now the driven axle received my attention. The Allen screw needed removal from the centre of the sprocket block. (Seen at left with its thick washer on the inner end of the longer, driven axle) This screw holds the block carrier/adaptor onto the hexagon on the inner end of the driven axle. It was a bit of a fiddle trying to rotate the Allen key in the confines of the reinforcing loops so I just used a spanner on the wheel hexagon and kept the Allen key still. Once th screw was removed I gave the back of the sprocket block a gentle tap and it fell free from its axle. Had it refused to come off I would probably have used a brass drift/bar and hammer to strike the carrier (between partial rotations) rather than hitting the sprocket block itself.

The spare wheel screw was again screwed into the wheel holding thread. The driven axle was easily drifted out with gentle blows to the claw hammer head which had again been fitted over the screw head as if it were a nail. After removing the outer bearing , the inner bearing was quickly removed with a few gentle taps of  the plastic hammer on the end of the axle after re-inserting it into its housing. The results can be seen in the posed pictures above. Less than 15 minutes work once you've seen how it's done.

Had the sprocket block needed removal from its carrier it would have been easier to fit the carrier back on the axle with a wheel in place. The wheel would provide the necessary leverage to overcome the considerable force required to remove a screw-on sprocket block. Though the carrier itself has flats for fitting in a vice or for using a professional quality bottom bracket spanner. My wild guess is that it is the same size as a bottom bracket fixed cup. Why would they make it a different size?

Below: The other side of the sprocket block showing the drive hexagon where the driven axle fits from the back. The parallel section of the inner axle end also helps to support the carrier.

Note how the much larger diameter shafts of the Longstaff need no local reinforcement where they meet the wheel hub. Unlike the Higgins, with its clever, matching axle cone and hub recess. The larger overall dimensions of the Longstaff components means more weight of course.

I have read that Longstaff axles break very rarely indeed but the axle remains attached. Higgins axles  are supposed to break such that the wheel rolls away from the tricycle. The rider is unlikely to enjoy such a catastrophe and one would hope this occurrence is extremely rare and best avoided in traffic.

The Longstaff trike conversion, as shown, weighs a fraction under 9lbs without the wheels. You'd need at least one rear wheel for a bike so a conversion set adds one extra wheel for a total  of 12-13lbs to any bike with similarly lightweight rear wheels.

The abbreviated OWD dismantling instructions:

1.  Using a 2.5mm (or equivalent) hex key remove the four  Allen grub screws from beneath the bearing housings and store safely.

2.  Remove the rear wheels.

3.  Remove the circlips from both outer bearing housings and store safely. (Use circlip pliers)

4.  Insert screw into right hand axle end and draw out axle and outer bearing with gentle taps to claw hammer head with soft hammer

5.  Slide off outer bearing and use reversed axle to gently drive out inner bearing from right inner axle housing with soft hammer.


6.  Undo the Allen screw holding the sprocket block adaptor to driven axle and store safely.

7.  Tap block carrier to free it from inner end of axle hexagon.

8.  Insert screw in outer end of axle and draw out driven axle and outer bearing using claw hammer and soft hammer. Catch block as it falls free.

9.  Slide off outer bearing, reverse axle and drive out inner bearing using axle and soft hammer.

10. Clean and check components

An alternative to the use of a screw and claw hammer might be to use the road wheels to lever the axles out. This would require some care not to spoil the finish on the trike if working alone.

Now all I have to do is get the bearings and axles safely back in and describe how I did it. That is a task for tomorrow:

Reassembly proved even easier than dismantling. I cleaned and greased the exteriors of the four bearings and axles and cleaned their housings. Finger pressure alone managed to seat two of the bearings. I used the driven axle to push one reluctant, inner bearing gently into place with very gentle taps of a rubber hammer. The final bearing responded easily to a carpenter's sliding cramp.

Ideally, one should never push or hit the inner race of a journal bearing to seat it or remove it. A bearing should only be pressed or driven in by the outer race. In this case there is little choice since one cannot get behind the bearing to push the outer race. Since one wants to reuse the bearing in most cases one should be as careful as possible not to distort or dent the bearing races. Rotating the axle slightly while removing it helps to avoid damage to the bearings.

I used a pair of bent-nosed, long nosed pliers to close the circlips enough to get them back into their tracks in the outer bearing housings. I shall have to find another pair of circlip pliers as mine have disappeared.

The sprocket block on its adapter was replaced on the driven axle and the hex bolt was tightened with a 5mm hex key. A 13mm ring spanner was used on the wheel drive hex to deliver enough torque to finally tighten the adapter fixing bolt securely.

Finally the four little grub screws were inserted into the bottoms of the bearing housings and tightened gently with a 2.5mm hex key. The hex socket adapter fixing bolt is visible beyond the gear hanger boss in the image below.



Later Longstaff two wheel drive. (2WD)

Here is a list of operations to dismantle the Longstaff 2WD assembly. Supplied to Alan Schmidt by Longstaff to aid removal in a land without trikes and very few mechanics with Longstaff trike experience.

NOTE BEFORE STARTING: Dismantling the Longstaff 2WD assembly requires a very long 4mm Allen key to reach through the empty, right side, axle housing to undo the (hex socket head) Allen bolt inside the sprocket block carrier. Such a tool could be quite easily and cheaply made from a sawn off stump of 4mm Allen key welded/pressed or beaten into a suitable length of steel tube with cross holes drilled for a Tommy bar at the far end. Alternatively an extra length of the steel pipe could be gently bent at right angles to form a lever to apply sufficient torque to the Allen key to undo the 4mm hex socket-head bolt. Without having seen a 2WD assembly, without the right axle in place, I cannot say whether a standard 4mm Allen key will do the job. Thereby avoiding making an extension pipe for the hex key.

Longstaff Two Wheel Drive removal and refitting instructions:

1.  Remove wheel axle bolts and loosen wheels .

2.  Remove brake calliper (if any) and discs.

3.  Undo all four M5 grub screws

4.  Remove circlips

5.  Pull LH shaft out 2mm and RH shaft out 2mm.

 6.  Hold the RH wheel, locate an open spanner onto the 19mm nut located on the RH
   shaft. Undo the nut by turning the RH wheel backwards
7.  Take RH wheel off and remove RH shaft a little at a time.
   The 19 mm nut will remain in the cassette.

8.  Thread the long 4mm allen key through the RH side of the axle, through the 19mm nut (the nut should not be attached to anything) At this point, before actually undoing the Allen key bolt, check to see if it was tight to start with. If it is loose, tighten and re-assemble the unit (reverse of above instructions) to see if this solves the problem

 If the Allen bolt was tight continue as follows:

Undo the cassette by holding the LH wheel.

Take the LH wheel off and remove LH shaft (as with RH side)

9.  The cassette will then drop out (can be tricky with the nut and spacer still in)

10.  Put a cassette splitter into a vice and to remove the LH lockring. BUT, before doing this, check to see if the locking ring was tight. If it is, continue

Once the locking ring is removed, the large aluminium spacer and cassette will then come off the body.
You can now put an extra spacer between the large spacer and the cassette.

You should now be able to put the cassette back on and tighten up the locking ring. Check to see if this has taken the movement out of the unit

Re-assemble  (reverse of above instructions).

Here is a link to an illustration and instructions on Longstaff's 2WD:

Click on any image for an enlargement. Back click to return to the text.