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For Information
Johns mod to his nose leg on a HDS
The upper and lower bearings on the older CH601 Zodiacs will begin to
wear considerably after a couple of hundred landings or so. It is
somewhat difficult to replace the existing aluminium parts without some
major disassembly. A better solution in my view is to use the new
CH601XL bearing materials and modify them to suit. The new bearing
material should last longer that the original set-up and are easier to
replace in the future.
Unfortunately I have not got any accurate dimensions but as most
aircraft will probably be slightly different this isn't a major issue.
Before you start on this modification it would be wise to check the
condition of the upper bearing as it to may need some remedial
attention. If so a similar technique can be used.
The basic steps are.
1. Order the lower nose gear leg bearing from Zenith.
2. Remove cowls, jack aircraft.
3. Remove nose gear bungee. Also might be
easier if nose wheel together with the wheel forks are removed from the
actual gear leg.
4. With the gear leg removed mill (or file) each side of the new
bearing so it sits snugly between the existing right angles of the
current lower bearing set-up.
5. Mill the back of the new bearing about 1/2" x 1/2" (12mm x 12mm) as
shown on the picture.
6. Clamp the new bearing around a 2" tube (Or use the gear leg), fit
the
front AN3 bolt (Bearing should be pre-drilled by Zenith) and then drill
a 3/16" hole to accommodate a long AN3 behind the gear leg in a similar
manner to the front AN3 bolt.
7. Fit the new bearing to the gear leg and bolt together with the long
AN3 bolts.
8 Position the gear leg back in the aircraft and ensure the new bearing
is seated on the original aluminium angles.
9. Clamp the new bearing onto the aluminium angles and from underneath
drill up thru existing bolt holes into the near bearing. It is not
necessary to drill right thru the new bearing.
10. Remove the gear leg and remove the new bearing from the gear leg.
11. On a flat work table firmly clamp the new bearing and insert the
front and rear thru AN3 bolts, then thru drill the mounting holes done
in step 9 ensuring they are at right angles to the bottom of the new
bearing.
12. From the top of the new bearing use a 1/2" slot drill to recess the
AN3 holes so that they will accommodate and AN3 bolt head and washer
BELOW the level of the bearing surface.
13. Refit the new bearing to the gear leg and tighten the thru AN3
bolts to the correct torque.
14. Position the gear leg and bearing into position in the aircraft.
15. Using the correct length AN3 bolts from the top of the new bearing
work into position so that the bolts go thru the existing holes in the
lower angle aluminium.
16. Refit the front section of the existing aluminium bearing and fit
washers, nuts and re-torque.
17. Refit bungee etc.
19. Probably advisable to lubricate with some lithium based grease.
20. Complete re-assembly.
Rega
rds, John Livsey
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