396 replies to this topic

[stuart bowes]

so .. bonnet hinges

it's a no-go unfortunately, I got them fitted with the bonnet down in the right position (it pushed down into place better than this picture shows, that was after a couple of ups and downs)



and when I managed to get the bonnet in the up position, the angle was pretty good



BUT that's where the good news ended, the action didn't work right at all, you have to reach in through the grill and tap upwards underneath at the back edge, pull the rear up, and then it starts lifting from the front (at which point it moves nice and smooth to be fair)

maybe if I played around with the angles and arm lengths a little longer I could dial that out, but it's only solving a problem that shouldn't exist in the first place

oh well can't win them all, at least I tried I suppose. I do have another much simpler idea to get a better upwards angle which involves adapting the standard hinges, so I'll give that a go next I suppose

In other news I have stripped down both subframes and now have muck all over the floor which needs a good scrub down, but they're both ready to go off for blasting while I start getting back on with the actual work instead of messing about

Edited by stuart bowes, 22 July 2023 - 01:41 PM.

[elliot341]

Just electrify it in a binky type way......

[stuart bowes]

yeah knowing my luck though it would be that one time in the pouring rain on the side of a motorway it refuses to work and I just need to change a fuse or something lol

 

it sounds great in theory but I dunno 

 

(in fairness they only automated the flip front and the actual bonnet was manual not even they are that mad)

Edited by stuart bowes, 17 July 2023 - 01:54 PM.

[stuart bowes]

so the next attempt is a lot simpler, but relies on spring strength being just right

 

 

a modified version of the traditional bonnet hinge arm, but with a sprung extra hinged section which allows an extra 40deg (to totally vertical) to a limiter stop and another limiter to hold it at the normal position

 

the spring (possibly 2 each side) has to be strong enough to hold the normal position while opening and closing without being 'floppy' .. but not so strong that that bonnet deforms over time being pushed into the extra lifted position.  Also, to hold the 'normal' position until right at the very up-most position so the back corners of the bonnet don't foul the wings on the way up (because of the sort of 'wedge' shape of the bonnet, it's not straight edged)

 

Gas struts would have to be strong enough to hold the bonnet up in that extended position, but not so strong that the the bonnet gets deformed in operation (although at least with that I can play with positioning to get leverage on my side)

 

If the gas struts don't work with it (a definite possibility) I would be willing to use some other sort of latching strut like this https://www.carbuild...tay-large-300mm (ideally a little sleeker if I can find something, but the angle of opening is more important to me than the visual style of the strut)

Edited by stuart bowes, 19 July 2023 - 10:14 PM.

[Steve220]

Is there a way you could make an adjustable spring? I know its a bit more effort, but would allow you to dial in just the right amount of load.

[stuart bowes]

I suppose there could be a selection of fixing points to chose from which would effectively adjust the pre-load

 

I've found some which are 16mm diameter and 2mm wire (that's what the dotted lines above are modelled on) so should be pretty strong, the smallest distance (bonnet down) is about 80mm and I've chosen 70mm unstretched length, so there's already about 10mm preloaded on it which should at least stop it rattling or being loose.  and I've ordered 4 of them, so I'll start with one each side and if that isn't enough, go for 2 each side.  hopefully that gives me enough options to start with anyway..

Edited by stuart bowes, 25 July 2023 - 08:03 AM.

[KTS]

just a thought; but if the point of the exercise is to get the bonnet to open further can the hinge itself be reshaped to give better clearance to the scuttle (as that's what limits it) ?

[stuart bowes]

not really no, or not that I can see anyway

 

you can't make the dip go any lower because it hits the bulkhead, and that's the bit that also hits the scuttle, so that's the limit in both directions.  you could make that bar a little thinner but obviously, weakness, and it would only gain you about 5 degrees, it needs about 40 degrees

 

you COULD cut two slots in the bulkhead and then make it a deeper dip I suppose, but I didn't want to do that really, I'd rather make it a modification that someone could just unbolt and put the originals back on if they wanted

 

I did consider it though I admit

Edited by stuart bowes, 25 July 2023 - 12:07 PM.

[KTS]

i was thinking that as the hinge pivot point is away from the bulkhead, reshaping the hinge to include an angled return to the pivot point would make the bottom of the bonnet move forward as it opened which should allow the hinge to pivot further before it hit the scuttle

 

makes sense in my head, but might not translate into reality 

[stuart bowes]

new hinges part 2:

 

marking out (3mm plate)

 

 

drilling and cutting

 

 

(work in progress)

Edited by stuart bowes, 29 July 2023 - 07:34 PM.

[stuart bowes]

also following discussions on another thread rolled the dice and committed to replacing the radius arm pins myself

 

not sure what I was worried about to be honest, other than sweating due to warm weather it was fairly straight forward

 

 

1 x cheap reamer 25/32-27/32 (19.8-21.4mm) and handle off ebay, about £25 total

 

some sockets and extensions, a bit of M10 thread I had knocking about. nuts and washers (no cost)

 

and the new pins themselves £20 per side from wood and pickett on ebay, job's a goodun, lovely and snug, turns smoothly with no resistance but no lateral play at all

 

I basically copied this video:

 

 

with the addition of blow-torching the outer sides of the casing to expand it a little and get the bush moving more easily.  the bearing more or less fell out during that same process

 

putting new back in, used a block of wood and tapped them to get started, then wound in with the stud, went in nice and easy no probs

Edited by stuart bowes, 29 July 2023 - 07:42 PM.

[stuart bowes]

just a few more pics of work in progress

 

one bonnet hinge finished cutting and welding .. made the mistake of spraying one bit with primer then realising it still needed tweaking. duh

 

 

checking fixing points against other unmolested hinge when in the fully down position

 

 

and one completed 

 

 

as it turns out I ended up with 50 degrees which gives me a bit extra to play with.. that would go almost back to the windscreen but I would want to adjust the limits slighly of course to stop that happening

 

the sort of mitten shaped piece is welded on to the side of the original hinge, and then the original end with the two stud fixings is cut off, which means the new additional piece bolted on to the side of that is in line with the original piece. if that makes sense (anyway, it lines up correctly)  the big hole I've drilled in the original hinge is just there to locate that pivot point before welding, and then it gets cut off.  there's about 10-12mm overlap and it's welded on all 4 edges, totally solid.  when it comes to painting a tiny fingertip smearing of filler should make the joins look tidy

 

springs still on the slow boat from china grr

Edited by stuart bowes, 31 July 2023 - 06:59 PM.

[Retro_10s]

Enjoying the fabrication on this a lot!

[stuart bowes]

cheers :)

 

further modifications required however, as initial testing found the top edge was clonking against the scuttle .  to be fair I thought that might be a risk

 

so that's now trimmed down as per the red line and actually I now have a few more mm clearance than the originals

 

 

what that does mean is I now have no upper limit stop so I'll have to figure something out for that.  

 

also I've ordered a pair of clevis pins and some smaller thinner washers to bring the overall width down as well, due in a couple of days

 

meanwhile I can get the other side made up and hopefully those bloody springs will arrive at the same time

Edited by stuart bowes, 02 August 2023 - 07:43 PM.

[MacGyver]

Nice project!👍

You could just add some material here:
 IMG_20230803_081227.jpg   115.53K   0 downloads

Ben