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Essential
bonnet lock and safety catch servicing for an MGB
Regular
cleaning and servicing the MGB bonnet release and safety catch
on an MGB and its derivatives are essential as reports of a
few failures of the lock and safety catch leaving the bonnet
free to lift in the airstream and blow up over the windscreen
are a real concern. Here Ralph Coulson describes his regular
inspection and maintenance routine. (May 2012)
Because of their position on the MGB the lock and safety catch
are subject to driving rain, road salt contamination, dust and
grit. Fortunately the design is both rugged and simple and general
wear and tear is comparatively low, even on high mileage cars.
However, due to the safety critical nature, good maintenance
of these components should never be ignored.
Cleaning
All components should be cleaned on a regular basis, removing
all traces of road dirt, grit, old oil and grease. I prefer
to use white spirit and a ½" paint brush. Then dry
with rag waste or tissue.
Inspection
Examine the release cable (not illustrated) for freedom of movement
and full return. Then
check the Catch Plate Return Spring (8) which should be close
coiled and free of corrosion, capable of 'snapping' the Catch
Plate (4) back to its rest position. The Catch Plate should
not have any appreciable wear on the underside where it engages
with the Lock Pin (5). The same applies to the Lock Pin shoulder
where it in turn engages with the Catch Plate. The Safety Catch
Assembly (11) should move freely on its pivot, be sure the return
spring is not damaged or broken.
Adjustment
When you are sure all the components are operating as they should
and are corrosion free, the Lock Pin (5) should be adjusted
to ensure the bonnet top surface lines up with the wings.
The Bonnet Hinges and Cup-lock Locating (3) can be adjusted
to equalise bonnet shut lines and alignment of the bonnet rear
with the wings. Check to make sure the bonnet opens and closes
freely without 'snagging'. |
|
No
|
Description |
|
3
|
Cup-lock
locating |
|
4
|
Catch
Plate |
|
5
|
Bonnet
Lock Pin |
|
6
|
Thimble-bonnet
lock |
|
7
|
Spring-bonnet
lock |
|
8
|
Spring-catch
plate |
|
9
|
Safety
catch |
|
10
|
Captive
nut-anchor |
|
11
|
Bracket-safety
catch |
Source:
MGB, Tourer, GT and V8 - Up to September 1976 Parts Catalogue
AKM 0039, page 108-K1
The Safety Catch (9) must engage fully with the Bracket:
Safety Catch (11). This may be achieved by
moving
the Safety Catch forward and aft on the bonnet under panel.
Check by viewing through the gap when the bonnet is released.
Lubrication
Most maintenance schedules would recommend white grease as a
routine lubricant because it is robust and waterproof. I prefer
light oil and regular cleaning.
One final check
If a 'flexible' body shell is suspected, especially with a Roadster,
a simple check would be to run a front wheel up a high kerb.
Release the bonnet, and then check if it can still be closed
freely without 'snagging'. Observing the bonnet to wing shut
lines could also give an indication of any flexing.
See our illustrated A4L PDF note online for better copies of
these photos. More |
