Puch VZ50 Wheel Rebuild

The original Puch wheels had badly rusted rims which had been painted silver and the spokes were thin with corrosion.

New stainless spokes and chrome rims were ordered and the wheel bearings and seals we renewed at the same time.

Rebuilt Puch wheel

Spoke specification was 168mm long with a 45 bend at the root.
Original diameter was 3mm with a 3.5mm thread but these were not available so 3.2mm spokes were used.
These were a bit tight for the threading pattern a better idea would be to 2.8mm or 2.6mm.

Before dismantling the old wheels a wooden gauge was made up to check any  dish or off set of the hub.

wooden gauge to measure off-set / dishing

To dismantle the hub, the axle spacer was removed and then the brake backing plate.

Removing axle spacer

Removing brake mechanism

The screw collar behind the brake plate was removed using an

Removing screw collar

The bearing seal was stuck fast and below the edge of the housing and so a self tapping screw was driven into it, and used to lift it out.

Seal removal

Behind the seal the shim washer was extracted with a magnet, a dental pick (and some patience).

Removing shim

To access the spoke heads the wire spring ring and cover were removed from the hub using a small flat blade screwdriver.

Removing spring ring

Removing spoke cover

Internal and external circlip pliers were used to remove both bearing circlips.

Removing inner circlip

Removing outer circlip

The axle complete with the left hand bearing was now drifted from the wheel hub, using the axle spindle as a drift to protect the hollow axle.

The axle removed with left hand bearing and seal.

Axle removed from wheel hub

To remove the left hand cover a brass drift was used through the hub holes to progressively push it free.

Drifting cover from hub.

Cover removed

The remaining bearing was drifted from the hub using a suitable socket and hammer.

Removing second bearing

Behind the second bearing was a thrust washer.

The hub was cleaned and polished on the lathe.

To re-lace the wheel the valve hole on the rim was used as a datum.

Because the spokes were all threaded from one side of the hub (unlike a bicycle hub) the spokes in the holes highest on the rim were threaded first.
That is to say, the spokes circled in red had to be threaded into the hub first.

The original threading pattern was a cross two spoke pattern which meant each spoke should cross 2 others on its way from the hub to the rim.

First spokes to be threaded.

The spokes were arranged so that access to the valve was easy by ensuring spokes either side of the valve would splay apart towards the hub, rather than cross over.

The first spoke was threaded to left of the valve hole.

Note the holes on the rim were staggered and should help the spokes point the right side of the hub.

First spoke

Working round the hub every-other hole on the hub flange was connected to every 4th hole on the rim. So there were 3 holes on the rim between each spoke.

Then the hub was twisted within the rim to ensure the first spoke was running away from the valve hole not across it.

First 9 spokes in place

The first spoke one the other flange was located with the hub twisted as shown by the red arrow.

The first spoke from the previous threading is circled in red.

The first spoke for the second side of the hub is circled in green.
This was the hardest spoke to locate, it had to start to the right of the first spoke but in an upper hole in the rim.

The other end of the spoke went into a hole  3 steps from the first spoke.

First spoke on the second side.

Following the same pattern as before the second set of spokes looked like this.

Second set of spokes complete

The first spoke on the third set crossed over the existing spokes.
To get started, the first spoke was located to the right of the valve hole and located on the hub as shown.

When located correctly it crossed over two existing spokes from the same side of the hub and into a rim hole which was angled the correct way.

First spoke of the 3rd set.

Third set of 9 spokes in place.

Third set of spokes in place

The final 9 spokes were put in the remaining holes.

Wheel re-laced

Replacement wheel bearings were standard ball bearings:
15mm ID x 32mm OD x 9mm

The seals were:
15mm ID x 32mm OD x 5.5mm

The first bearing was pushed onto the hollow axle using a socket as a drift. It was push down from the threaded end of the axle to the only remaining circlip.

Drifting first bearing onto axle

The axle was inserted from the "cover" side of the wheel and the bearing drifted into place with a suitable socket.

Locating axle

Drifting axle in

The seal was inserted and dirven in with the same socket.

Inserting new seal

With the hub flipped over; the inner circlip was replaced in the groove shown on the right.

Then the thrust washer and bearing were located.

Thrust washer

Second bearing

The bearing was driven in with the same socket but the axle was supported with the inner spindle in place with its head clamped in the vice.

Drifting second bearing in

The shim washer and bearing seal were replaced on the second side.
Seal and shim

The wheel was supported on a length of 10mm threaded rod, in a post clamped in the vice.

An angle plate was clamped to the post to hold a DTI to measure run out.

Progressive adjustments were made to get the wheel running true axially and radially.

The dishing gauge was also used to check rim offset.

Finally the torque on each spoke was checked for the same "note" all round when tapped with the spanner.

Truing up the wheel