Sprocket carrier bearing swap

 The bearing required for this is a 17x40x12 and I used a 6203 2zz double shielded bearing.

To swap the bearing you need to strip the carrier which is made of three parts- the sprocket, the bearing plate and the drive plate. Remove the loose spacer and use circlip pliers to remove the circlip retaining the bearing.  

Remove circlip and spacer

Remove the sprocket by removing the 3 14mm nuts and their spring washers

Remove the 3 14mm nuts and lift off the sprocket.

Lift off the sprocket here the upper view shows the bearing carrier plate which is penetrated by the three sprocket mounting studs from the drive plate beneath.

Sprocket carrier- bearing plate side

Whilst the rear shows the base of the drive plate with the three drive transmitting studs that engage with the hub.

Sprocket carrier drive transmission side.

The two sections just pull apart.

Sprocket carrier separated showing rear of bearing plate.

A second view shows the exterior side of the bearing plate with stub axle protruding. 

Sprocket carrier separated showing front of bearing plate.

Note that the bearing is inserted into the bearing plate from the front  until it rests against the flange at the base of its socket.  To remove a bearing from a socket you would normally press it out by pressing against the outer race only. However in this case that isn't possible because the outer race is now hidden by the flange at the base of the socket.

Rear of bearing plate

There is no option but to press it out using the base of the stub axle which of course will bear on the inner race of the bearing. This will almost certainly damage the bearing but as I'm intending to change it anyway I guess in this case it doesn't matter! I used a double socket arrangement in the vice- the smaller socket pushes on the rear of the stub axle, whilst the larger surrounds the bearing, pressing on the front of the plate, and is deep enough to accept the bearing as it moves outwards.

Pressing out the old bearing

The old bearing is pressed out together with the stub axle.

Bearing removed

The stub axle is inserted from the other direction, the flange of the stub  axle resting against the rear of the bearing. To remove this its necessary firstly to protect it. I refitted the stub axle nut flush with the end of the stub to avoid thread damage.

Socket arrangement to press out stub axle

I then selected a socket large enough to press on the bearing outer race and used the vice to press the stub axle out of the centre of the bearing. This worked well and the extracted stub axle is shown below.

Stub axle removed

Clean all recesses and the inserts then start to fit the new bearing by hand. Once it started to bite I used the old bearing as a drift to tap it into the recess until it bottomed out on the flange and exposed the upper circlip groove. I then cleaned and refitted the circlip. 

The stub axle was then pressed into the base of the bearing from the other side using the vice against the base of the stub axle and a deep socket on the other side; large enough to rest on the bearing inner race, and deep enough to accept the stub axle as it emerged through the bearing. 

Stub axle inserted into new bearing

Bearing plate reassembled

The carrier was then reassembled by reversing the above process.

Fuel tank and tap

 Fuel tank is sound but badly affected by surface rust and associated pitting- the tap looks to be in poor condition.

Tank badges are held with 3 M3 screws each- 3mm countersunk. These were stiff and one was broken on removal- I will renew them all.

The centre alloy trim strip is simply clipped through the eye at the rear of the tank and under it at the front. I straightened and removed the trim strip.

Alloy trim at rear

Alloy trim at front

Tank with trim removed

The strip itself has a chequered flag design- I don't know if it was original but its delaminating and in poor condition so I removed it.

The trim strip sits in a rubber channel which I removed and cleaned for reuse.

I will try to polish the trim strip as it does cover the join in the tank but the metal is pitted and I'm not sure how much I can rub it down without weakening it. I'm also thinking that even though the chequered tape is not original, it does represent something of the history of this bike so I feel justified in reinstating it.

I rubbed down and skimmed the tank with P100 before rubbing it again to fill the pits. Finally resprayed in primer- white and masked up for the grey.

The Fuel tap

The tap itself is a complex design- Note that the intake for the bulk tank fuel (long pipe) is unfiltered as it leaves the tank- there is a second filter integral to the tap at its base which filters it before it enters the carb. The reserve tank fuel (from the lower part of the tank) is presumably more likely to be contaminated, so is filtered as it leaves the tank by the small conical filter seen in the picture, and again by the integral tap filter below. Reserve fuel is thus double filtered. The tap screws onto the tank in a clockwise direction but the union nut has 2 threads and also connects to the tap body in an anticlockwise direction. 

Fuel tap- note longer main fuel inlet pipe and conical filter covering reserve inlet pipe

The lower union nut (tap to fuel hose) unscrews anticlockwise and also releases the fuel exit spigot and its filter. Looking inside the tap revealed both tap and filter clogged with powdery debris and residue. The filter was stuck onto the exit spigot

The exit spigot pulled out of the lower union nut, I detached the remains of the hose and its ferrule. At this stage the lower filter remained attached to the spigot.

Components of the lower spigot- filter attached broken pipe and ferrule.

The upper union nut unscrews anticlockwise as normal and comes away with the top filter.

Tap as disassembled

I blasted everything through with carb cleaner and then cleaned in the sonicating bath.

Both filters were torn and both showed deterioration of their sealing washers so I carefully freed them from the remnants. In fact both filters are shaped like hats- the upper filter is like a witches hat and the lower more like a bowler. Both have a sealing washer bonded to the upper surface of the "brim" and new filters seem to come with this. However in my case these parts had deteriorated badly and had to be picked off carefully although that foes allow me to fix the tears in the gauze. 

Upper filter "witches hat"- sealing washer eased upwards

I was able to trim them to remove the torn sections and then flare the gauze out to create a new "brim". This I sandwiched between two fibre sealing washers in each case. 

Lower filter with brim and lower sealing washer 

Upper sealing washer placed above the brim.

I did the same for the upper filter and reassembled the tap. Hoping this will be fuel-tight.

Reassembled tap- looks cleaner at least!

Repainted and assembled the tank tap and badges.

Rear end strip

I have now reconstructed the front of the bike but so far not touched the rear. I decided to strip it down and remove the rear wheel. I'll paint all the components off the bike with the exception of the rear swinging arm which I will not remove unless I have to.

First step was to remove the bench seat and its hinge strips as described previously. This exposes the seat catch which is held by 2 bolts and simply removed for de-rusting

I then removed the rear wheel so took some initial pictures of both sides of the hub so I have a record of how it looked before starting- there is a lot of corrosion which is going to take time to remove!.

Rear wheel rhs showing brake cable attachment and axle fixed hex end

Note the grease shield tube appears too short. Also the torque plate between the swinging arm and the hub.

Second view  note chain tensioners look badly corroded

On the lhs of the bike the situation is a little more complex. The chain adjuster also seems corroded, but there are apparently two nuts on the axle: The outer is the true axle nut and holds the axle in place (remove it to remove wheel only). The second nut actually screws onto a hollow stub axle through which the rear axle passes. The stub axle itself is pressed into the bearing of the sprocket carrier. I was obliged to dismantle this which is covered in a separate post. The inner nut holds this stub axle (and thus the sprocket carrier) onto the swinging arm.

Right hand side showing chain tensioner (also corroded) and double  nuts on the axle. 

I loosened the outer nut and noted the washer between the two

After removing the outer nut, the axle can be tapped out towards the right, but since I was stripping everything I also removed the inner nut to release the sprocket carrier. It is not necessary to detach the sprocket carrier in order to remove the wheel.

Both nuts and intervening washer removed from the rear axle.

I tapped the rear axle out towards the right 

Note the fixed hex end of the axle on the rhs and the washer beneath it. 

Rear Axle loosened and emerging from RHS of the hub. Note the brake cable adjusting nuts and hex ferrule on the cable end.

I order to remove the wheel its necessary to detach the brake cable. I found this quite difficult. Use the two nuts and hold the hex end of the brake cable in order to de-tension the cable. Once the cable was loose I tried to detach it from the nipple saddle- but there is insufficient slack to do this. It may well be preferable to release the cable at the foot control end, but in the event I chose to release the saddle from the brake backplate. This is a simple clevis pin fastening secured with a split pin to the rear. This is (just) visible looking down between hub and saddle to see the small split pin in the clevis. Although its hard to see it was relatively simple to straighten and pull out the pin.  

Strighten the bent ends of the split pin...

And ease the pin out

Pin emerging from clevis

So that the clevis pin itself could be eased out detaching the saddle from the brake lever.

Brake cable saddle detached.

Its still a little awkward to detach the rear brake cable from its tensioning bracket on the back plate because this is angled. Seems to be an odd design and this is going to be an interesting reassembly!

Disengage the rear wheel chain tension adjuster- in my case this is very badly corroded and will need to be replaced. Note here that the adjusters are different sizes, that on the left fits over the axle and is a 12mm hole. The rhs fits over the stub axle and has a 16mm hole.

Disengaging the rear wheel alignment adjuster.

The axle was then drifted out to the right.

Axle emerging from the right.

Not that the sprocket carrier remains in position- although its loose here because I removed its securing nut.

Sprocket carrier left in place

The rear end of this bike is one of the oddest I've worked on. As I'm going to be removing and disassembling the sprocket carrier, I took a few pictures to remind me of how it was originally assembled. One thing I did note at this stage was that there was considerable rotational play between the sprocket carrier and the hub. That didnt seem right.

Sprocket carrier fitted closely  against the hub

Sprocket carrier stub axle. Note this is 15mm in diameter

I had expected to be able to remove the wheel complete with sprocket carrier at this stage- I was sadly mistaken. Even when the axle is withdrawn entirely, there is insufficient room either to remove the wheel with the sprocket carrier attached or to remove the sprocket carrier on its own. Checking the manual (duuuh) showed that in order to make space its necessary to remove the brake torque plate linking bar. I suspect this should simply slip out. but in my case this was dirty, corroded and  jammed. I'm copying this picture here for illustration- you can see the axle passes through the torque bar immediately behind the swinging arm. The far end has a lug and a groove to lock the brake plate to the swinging arm during braking. It seems counterintuitive but you release this by tapping it forwards until the lugs disengage from the groove in the torque adapter. You can then swivel the torque adapter towards vertical and lift it out.

Brake torque bar situated between hub and swinging arm. The torque bar has a bore for the axle, linking to a double lug that anchors the brake plate to the swinging arm to prevent it turning. Note this axle 12mm in diameter.

Torque bar removed- note hole through which the axle passes and the lug/groove arrangement at the other end.

Brake torque bar

Once the torque bar was out the wheel could be removed. The sprocket carrier then detached from the hub. I noted that there is a spacer above the sprocket carrier bearing which fell off so was carefully stored. The bearing itself wasn't too noisy but it did seem stiff and looked corroded so I decided to change it anyway (see separate post).

Looking at the rear wheel after removing the sprocket carrier revealed the reason for the rotational play in the wheel. The rear of the carrier has three pegs which should locate in rubber bushes pressed into the wheel hub itself. This would provide a smooth shock absorbing take up of drive forces akin to the cush rubbers of a Honda C90. However in my case all three bushes were completely missing meaning that the pegs were simply slopping about in the much larger holes! I'll have to replace or manufacture some replacements.

Rear wheel rhs. Note three circular holes in the hub which should contain rubber bushes.

The brake back plate also detaches from the lhs of the hub with the brake shoes still fixed behind.

Brake back plate.

Operation of the lever was extremely stiff and I'll need to remove and clean the plate as well as freeing up and re-greasing the pivot pin. This is pretty much as described for the front wheel so I won't list it here unless I discover something odd.

Rear brake shoes and spring fixed in the brake plate.

In fact I will draw attention to the retaining plate fixed over the moving end of the shoes. This isnt mentioned in either the parts list or workshop manual. I found this was a later modification introduced by NSU to prevent brake noise.

Winged retaining spring plate- remove it to allow the shoes to pivot easily for removal.

Just lever the circlip back and lift off the washer and the spring clamping plate beneath.

Spring retaining plate and washer- note square hole. Dont reuse circlip

Unlike the front brake the rear was very stiff and siezed. There was certainly a lot of rust and little grease on the pivots or rub points. One shoe was stuck firmly in the actuator spindle's groove. This had to be levered out. The actuating spindle was still corroded and lacked lubrication. Its removal is exactly as the front brake except that this time I remembered to mark the brake arm and spindle for correct positioning on reassembly.

Removing nut and washer. Punch marks for correct reassembly.

As with the front brake, there was a sealing washer beneath the brake lever arm.

I cleaned everything up but when I came to reassemble it was clear that the pads of one brake shoe were too thick and wouldn't slip into the actuator or pivot point grooves. This explaind why they wouldnt come out. I had to file the ends down until they could slip in and move easily. This is undoubtedly the explanation for the stiff-to-non existant braking action on this brake. I also included a little smear of brake grease  where the shoes rubbed on  the retaining cups and ends of the spring plate.

Rusty shoe pivot point

It was quite tricky to reassemble to ensure that the shoe spring engaged with the pivot pin below the shoes.

It was also tricky to reassemble the shoe retaining anti-noise spring clip. Put a spot of brake grease where the springs will rub on each shoe and then assemble the clip and square-hole washer.

The spring required compression before I could fit a fresh E clip into the groove on the actuating arm and I applied this using the vice. I used a socket to protect the brake arm and positioned the brake plate in the vice such that it could compress the spring clip and allow me to slip the new E clip into the retaining slot with some snipe-nosed pliers. I still think this i overkill but then ive not heard the "noise" it makes without the clip!

Brake assembly used to compress anti-noise clip.

Vice presses on washer below the actuating arm- (not on the arm) to compress the spring clip

Socket used to protect the brake arm.

New E clip installed

E clip holds spring plate in place ensuring the shoes stay down.

Frankly, this all seems like overkill for such a small bike and it also makes the brake rather stiffer to operate, but having checked I can confirm that this is actually real and correct for the Quick 50.

Rear Shock Absorbers

I released the shock absorber by unscrewing the double nuts of their top mount.

The shock could then be removed from the top mounting bracket- note the arrangement of rubber washers and cover caps. The rubber is fitted below both the upper and lower caps.

Shock absorber upper mounting- rubber washers in positions as shown.

Upper rubber washer inside top cap

Arrangement of washer s and caps on the shock absorber.

I didnt want to dismantle the rear shocks- its true that they seemed to have little in the way of shock absorption, but they weren't leaking and frankly the new front shocks I had bought were very similar in (lack of) effectiveness. I did however need to remove the metal shrouds in order to clean and paint them. Disassembly was identical to that described for the fronts. Again take care removing the shrouds - they just unscrew up the shock absorber shaft but they can be tight- bare in mind that the screwdriver slot in the top of this shaft is made of cheese and lock the shaft using the nuts screwed against one another, rather than a screwdriver to hold the shaft.

Unscrewing the shroud

Shroud removed for painting

Spring removed to clean the shock prior to reassembly

Bench seat subframe and Rear Mudguard removal

The seat subframe is held by two small bolts at the front which double as fuel tank rear mounts. These have already been removed during my stripping process. In addition there are two  large through bolts towards the rear. The larger bolt passes through the shock absorber mounting bracket and transmits suspension shocks to the frame. Loosen the nut and note the washer beneath. 

There is a nut and double washer on one side and a hex head on the bolt. Unscrew this and withdraw it by tapping from the rhs.

Working the subframe mounting bolt free from the subframe and mudguard.

The second rear bolt is narrower, it unscrews and taps out of the tube mounting on the mudguard- this bolt and washer are shown below.

second bolt withdrawn, the seat subframe can then be taken off.

Off to clean de-rust and repaint.

 Mudguard

The mudguard is then held by two pairs of bolts passing into welded brackets on the frame. These need to be undone from inside the mudguard where they are conveniently hidden by accumulated grit and road muck.

Side view -Rear mudguard- front base attached to welded bracket on frame

Side view - Rear mudguard attached to welded bracket on frame- appx halfway up

Mounting bolt heads for the 4 bolts are visible inside the mudguard- two upper and two near the bottom of the mudguard.

Interior view - Mudguard mounting bolts (4) just visible

Remove these and the mudguard comes free- Note that the wire connecting the rear light has no junction so I cut this to release the mudguard and I'll insert a connector which will be protected below the seat subframe when rebuilt. 

The mudguard also carries the number plate and rear light. The former was too corroded to be unscrewed and had to be drilled off. It will require derusting and repainting. Luckily I can eventually  use it as a support for an embossed number plate rather than as a base for stick-on numbers. Its far too pitted for that. The rear light was in good condition and was dismantled for cleaning and storage.

I completed the painting of the frame now that the rear section was accessible..

Brake Pedal and Swinging Arm

Even after disconnecting the rear brake cable, the brake pedal remained stiff and hard to operate. I needed to remove it for examination. The cable is attached to the pedal via a saddle- and like the brake plate attachment, there is insufficient room to slip the nipple out via the saddle cutout.

Cable saddle attachment.

But also like the brake plate attachment, the saddle clevis is also retained by a small split pin.

Saddle clevis and split pin

 I removed this to separate the clevis and disconnect the cable.

Clevis and saddle

The pedal is attached with a circlip, washer and return spring which is braced via a hole in the swinging arm.

Brake pedal mounting point and return spring.

Circlip levers off along with the washer beneath it.

Pedal washer and E clip

Lever off the return spring- note this is retained in  hole in the swinging arm.

And pull off the pedal. The shaft was covered in the disintegrated remnants of a plastic bush that had jammed it making movement very difficult. This arrangement seems poor compared with other bikes where a bronze bushing would have been preferable.

Brake pedal mounting- note debris from degraded bush, spring still held in sw arm

This was cleaned off and the pedal was cleaned as well ready for repainting.

Brake pedal pivot pin cleaned

Swinging arm

The Rear swinging arm is held on a pivot pin passing through plastic bushes. Once again this seems  inadequate and I had expected phosphor bronze. Although there was no side-side play in the mounting- what was visible of the bushes appeared to be in as poor condition as that on the brake pedal shaft so I decided to remove the swinging arm and renew the bushes. The pivoting pin is held by a circlip at each end.

Swinging arm circlip surrounded by remnants of crystallised plastic bush.

Swingarm position before removal.

Again- pre removal shot of arm position.

Remove the circlip and tap the pin out using a soft drift.

Swinging arm pivot pin.

The arm can then be pulled off- note that the spacer washers will fall out once the swinging arm is withdrawn.

Spacer washers

Everything required a total clean. New bushes are available for the arm and the brake pedal but these seem to mount up in costs so I decided to try and make my own using acetal delrin. See next post.

Cleaning and repainting went pretty much as expected and was a filthy job. O e thing that surprised me is that thecrear mudguard turned out to be made of aluminium and fabricated in two halves joined together with sealant/adhesive.  Unfortunately this had detached and the cleaning process revealed a few cracks.

Inside of mudguard- cleaned and primed i etch primer- the cra where sealant was lost is evident.

Exterior view

Obviously the mudguards will be held together by the two bolts that pass through them and sealant is necessary to prevent rust. Further the gaps would be hidden by the seal when assembled but even so I thought it best to reseal and so I used PUC18 or tiger sealant to fill the spaces.

Exterior view after applying new sealant.

I overpainted the interior of the guard with grey stonechip. On the outside  I reprimed over the cured sealant before applying a top coat grey.