436
Caution with your bonnet
catch
Malcolm Venables reported a dangerous
experience with his bonnet catch failing which allowed the bonnet to blow up onto
his screen. Here he describes how it happened and recommends the bonnet catch
is checked carefully as a service item. (Sep 11)
Malcolm
Venables' posting on the V8 Bulletin Board was - having finally got my Factory
MGBGTV8 back on the road last year, I have been gradually ironing out all the
wrinkles. A couple of months ago whilst driving home from picking up a new computer
monitor I had the bonnet fly open. Now I know this is not an unheard of experience,
but it did take me by surprise particularly as I make a point of listening for
the catch to click home when I shut it. Fortunately it happened as I was leaving
a 40 mph limit and on a straight road with little traffic, so I was able to stop
the car safely. However the bonnet was now bent back over the windscreen and the
roof.
Careful
examination revealed that the primary locking mechanism had started to work loose,
that is the spigot that screws into a threaded hole in the bonnet and had a certain
amount of play, sufficient I suspect to become disengaged with the latch, however
I was surprised the safety catch didn't hold it.
I
have on rare occasions in the past known the bonnet to pop at low speed if not
completely shut, this would always happen very shortly after starting off and
would always be contained by the safety catch. However on reflection the MGB bonnet
has an aerofoil shape and I suspect that once 40mph or so is reached there is
sufficient lift to overcome the safety catch, certainly it is much more flimsy
than the one on my C class Mercedes for example.
So
the moral of the story is make a careful check of the condition of all the bonnet
securing devices and as, with everything else on the car, significant wear is
likely after 30 years. I was very fortunate in obtaining an unused heritage bonnet
on eBay for under £100 which I thought was a bargain, I have also now fitted
a bonnet strap just to be sure!
Editor's
footnote: the MGB Workshop Manual AKD3529 covers removing and refitting the bonnet
lock in Section | Back
to homepage
|
3 |
AHA5543 | Cup-lock
locating | | 4 |
HZA4551 | Plate-catch |
|
SF604041 | Screw-catch
plate | |
LWZ204 | Washer-spring |
| 5 |
14G2444 | Pin-bonnet
lock | | 6 |
4G3676 | Thimble-bonnet
lock | | 7 |
HZA563 | Spring-bonnet
lock | | 8 |
4G2494 | Spring-catch
plate return | | 9 |
HZA332 | Catch-safety |
|
PMZ308 | Screw-safety
catch | | 10 |
BHA4338 | Nut-anchor |
| 11 |
AHA5617 | Bracket-safety
catch | |
PMZ308 | Screw-bracket |
|
PMZ203 | Washer-plain |
|
LWZ203 | Washer-spring |
Source:
MGB/V8 Parts Catalogue AKM0039, Section - Bonnet and control details, page 108-K1
R:
The Body (on page R2 issue 10 in the 15th edition) and notes that when refitting
the lock "ensure that the bonnet lock, safety catch and the bonnet are correctly
aligned before finally tightening the securing screws. After assembly adjust the
latch pin to obtain ease of closing, lubricate the lock, catch, hinges and check
them for correct operation." Malcolm's note is a very useful cautionary tale.
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