MK IV bonnet support (and possibly MK V)

Has anyone come across or devised a simple but good looking way to safely hold up both sides of the bonnet at the same time. There are times when working in the engine bay or showing people the vehicle that this would be a useful safety feature - rather than 2 broom handles!!

A friend of mine used old violin bows, on his MG-TF…maybe they’d work on a MkIV?

:wink:

For many years I have used “ties” that limit the opening. Sorry I haven’t gone out and taken a specific photo but you can get the idea from this still taken from video. Not both sides together though.

I used bonnet tape of appropriate length tying between the radiator stays on the bulkhead and the rear bonnet catch screws.

Peter

Here’s a better photo.

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Aww, fiddlesticks indeed, and from a fellow musician, now I’m hurt. :violin:

3/4" oak dowel rods 32" long, stained and polyurethaned, with rubber furniture leg tips.




I stow them behind the battery.

Here is something that works for Mark V, some sort of clamp-on hinged rod, probably taken from some 1930s American car, or may have been a popular aftermarket accessory in the 30s, but I have not been able to identify it.
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On my Mark V, I used to use a notched broom handle with shower curtain hooks on each end. The shower curtain hooks, when latched, prevented the broom from coming free and kept the bonnet secure when up even in wind.

Nowadays I use a carb throttle linkage with swivel end and quick release. The quick release has a fixed ball attached on the inside of the bonnet near the back and also has a free-swinging ball on the radiator tie rod. Carb throttle linkages come in lots of lengths.

Photos below show the swivel attachment at rear of radiator tie rod, attachment at bonnet when raised, and attachment on tie rod when not in use.

Also in photos is one of the broom handles with shower curtain hooks to show how they attach and can latch/unlatch.

And for Paul Wigton, accidentally in the background on one photo is part of the front center fiberglass from my old Spec Racer when it still had the Renault livery used in the Detroit Grand Prix support race by the Archer brothers. I ran using “27” number due to my respect for Alain Prost. The piece in the photo is the largest bit of the front body after a small shunt I was involved in at Las Vegas some years later.

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Ah, Sport “No-goes:” fond memories! The car I completed my Nat’l licensing in!

Clearly Jaguar didn’t consider such a safety feature as a bonnet stay in those days or that people might need to raise it in windy weather without decapitating themselves. I’ll look to engineer something up better looking than my present broom stick handles to physically lock in position when up. Thanks for the photos so far.

I came up with a solution several years ago and this might help others. It is very discreet when fitted and is only visible if you raise the side panel up to the horizontal. It is completely reversible to original as there are no changes made to the body.

I can’t for the life of me understand why this fold-over design of bonnet wings persisted for so many decades. It caused strain and fatigue cracks at hinges, and wear spots or scratches on rest points. Why would they have thought that a mechanic only wants to work on one side at a time? Very inconvenient and time-wasting.

The principle is to utilise the existing screws on the chrome trim. The bracket is made from standard 3/4" x 3/4" aluminium channel and is anchored on the third and fourth screws from the back. At the front, the second screw in, a conventional ‘broom handle’ hardware spring clip is fitted to hold the end when closing the bonnet. The struts are made from standard 5/8" (16mm) st. steel curtain rod fitted with a crutch tip.

A few notes on the fabrication and fitting:
1 - The standard screws may not be long enough to pass through the aluminium thickness and you may have to make slightly longer ones. Note that the forward one of a longer screw needs to be trimmed in length so as not to project above the nuts. The reason being that the strut will not hinge back far enough to lock into the front clip.
2 - The broom handle clip is spring steel and the hole will have to be opened up a bit. It also has a concaved preset curve in its base, which is the reverse of the bonnet profile and you may need to pack the gap with a washer or two just under the centre to avoid over-bending the base when tightening. I added some heat shrink conduit to the legs to prevent scratching of the strut.
3 - The strut crutch tip must be fitted with a neat sized washer to prevent the strut punching through.
4 - The top of the strut needs to be radiused at the forward end to allow it to rotate for closure. I just used a 1/4" round head gutter screw with an acorn nut facing outward for appearances. If you add a flat washer between the channel and the strut, it will stiffen the hinging action and stop it inadvertently slipping when you are swinging it.
5 - I suggest insulating the aluminium bracket and the clip against the bonnet contact surface to avoid scratching the paint. I used black electrical insulation tape.

If you want some dimensions of the parts to give you a head start, just ask. I have done this for myself and others for 3.5, 2.5, and 1.5. For the 1.5, the struts land on each side of the battery and it would be wise to fit an insulating sleeve on the strut nearest the positive terminal and clamp. Heat shrink would be good for this.

Thanks for this further example and photos - I’ll gather some bits and pieces to engineer up in the workshop and have a go at making the aftermarket solution to the problem.

Hullo Dave,

I just remembered there might be a slight difference for the 1.5 bracket location in that I think it is mounted on the second and third stud not the third and fourth, but I can’t recall as it is a couple of years since I did a set for a colleague. I think this was because there is not much ledge in front of the battery. Check for the best forward position with the strut vertical, because there is still an imbalance front to back, the struts being well back from the c of g of the bonnet.

Peter

Here is a style of bonnet support for a Mk V. I don’t know the history of this as to whether there was an after-market version available, but this is well made, particularly the tight end curl.

(Note, This is for a Mk V in a Mk IV subject, but the discussion has crossed over a bit. Can the title be changed to include ‘Mk V’?)

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Thanks Peter. I’ll do a measuring up check for my 1 1/2 litre MK IV. I’ve also changed the subject title to include possibly the MK V as clearly the same bonnet issues is common across this as well as the MK IV.



Another interesting bespoke design - thanks for the pictures.

A raining day in the workshop and using what bits I had to hand, I have made my bonnet support stays. Some pictures that may be useful if anyone wants to make this after market modification that is easy to use, safe to work under, can easily be removed without noticeable marks, and I think looks OK.


A couple of 10mm diameter garden fencing spikes were cut and used for the 2 stays.

The bonnet chrome strip fixing bolts were used underside.

A couple of aluminium angle pieces were cut to fit between 2 of the fixing bolts, directly above the bulkhead radiator support brackets at each side.

A couple of angle brackets were fitted (to form a simple hinge).

2 U shape brackets were made to fit over the radiator support bar.

Heat shrink tubing was used over the brackets to prevent scratching

Angle brackets fitting to bonnet underside.

Couple of spring clip brackets made and fitted to next to end bolt to hold the stay in place when not in use.

Ends of each stay bar rounded and drilled to form hinge pin.

Other end of stay bar drilled, tapped, and U bracket attached.

Pivot hinge formed with simple bolts/nuts to fixing brackets

Bonnet stays simply locate over radiator support bracket bar

Bonnet stays clip up and out of the way when not in use

Some heat shrink tubing was used to stop any potential scratching

Can be used on any side

Or can be used together.

You need to make sure that the centre of balance of the bonnet is were you fit the hinge bracket (on the 1.5 litre this is directly above the bulkhead radiator support bracket), and the length of the stay is governed by your bonnet length - which is longer for the 2.5 and 3.5 litre. Ideally, if I had a longer bonnet I could have made the stays longer and that would have given a couple more inches of head room !!!

Nice work! Betcha you could sell a few sets of those.

This has been a really good thread, and I’ve collected some great ideas. Something for me to pursue during the winter doldrums.

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