Bonnet Hinges and Bonnet Stays

[Leo Bolter]

Ahhh, thanks lads, the penny drops! . . . . there's two springs in each side and the springs slide in both inner and outer tubes . . . . in that situation there'd be plenty of room for 2 x 200mm (if both springs were ever to be fully compressed). I've been concentrating on using just the one spring in each stay (although I did fleetingly consider that two springs in each may be needed).

But unfortunately, in my case, the top (inner) tube inside dimension is such that the spring won't enter that tube. That's what needs to be addressed in my set-up. Either a spring with a smaller outer diameter or a increase in the inner diameter of the tube . . . plus a change to one of the latching pin dimensions to allow the pins to enter into the gap (3/32") in the convolutions of the partially compressed spring. I had given that "peg" size as 3/16" in the original sketch (see my post of Wednesday, 21st December, 2010).

So what to do? . . . it looks like I'll be getting hold of a 13.5mm drill and welding a extension to it so I can open out the inner diameter of the top part of the telescopic stay and I'll also be re-machineing the latching pin "peg" diameter appropriately . . . (it may not need to be quite reduced to the theoretical 3/32", as the latching spring may force the spring gap open a little . . . .).

Your mention Keith, of a "safety wire" makes me think that I should make two end pads for each set of springs into which is soldered a length of Bowden Cable. The length of this cable would be a little longer that the normal fully extended length of the stays. This would stop the unit exploding like a spear-gun should the latch be released when the unit is off the car.

I'll report in when all is completed . . .

(Please refer to my other posts on Monday, 2nd April, 2012.)

[Leo Bolter]

EDITED: Important -Please see my post of Wednesday, April 04, 2012

This afternoon I have been pressing on with preparing to correctly assemble the stays and have whiled away my time by making restraint cables for the springs . . . presently I await a delivery of a 13.5mm drill that I'll weld a extension to so I can use it to clean out the bore of the smaller stay tube. Then it'll accept the spring.

As a matter of interest (maybe!) this is what I've done and how I went about it task.

I made 4 special brass "nipples" to solder onto the restraining Bowden Cable. These nipples also fitted inside the ends of the springs as shown in image 01


IMAGE 01 - The nipple.

I also turned up a couple of spring "joiners" (image 06) to keep the transition of the two mating springs in alignment.


IMAGE 06 - The joiner.

Two pieces of Bowden cable were cut to 36" and the ends "tinned" (this length suited my set-up, but I suggest you do your own measurements if this job is attempted by you).
Two of the nipples were soldered onto each cable with about 1/8" left protruding, (Image 02). After the solder had thoroughly cooled the protruding cable was burred by gently tapping with a hammer, (Image 03).


IMAGE 02 - Ist solder.


IMAGE 03 - Burred.

The solder was remelted and topped up. This was achieved by gently gripping the cable in a vice with the nipple facing down, so the top-up solder would make a neat finish and ensure the burr would be up against the nipple, under the solder (Image 04).


IMAGE 04 - 2nd solder.

Then comes the "fun part". The first spring was threaded onto the cable and the cable end gripped gently in a vice. Then the spring was compressed to a point where it was nearly coil binding and a gripping plier (Vicegrips ?) was used gently on the cable so as to hold the spring compressed.
Then the joiner was threaded onto the cable.
The second spring should now be able to be threaded onto the cable until it protrudes from the end of the spring (it may need a pair of long nosed pliers to do this). Grip this end in a vice and compress the spring, leaving about 4" of cable to work with. Attach another Vicegrip.
Slip on the other nipple and repeat the soldering.
When the clamps are removed the spring will be left curled up as shown in images 05 and 07, but they will (I hope) still slide into the stays okay . . . time will tell!


IMAGE 05 - Nipple fitted.


IMAGE 07 - Job done.

Tomorrow I'll know . . . . .

[Forumadmin]

Well that is certainly more complex than I thought of! My restraint was a vice holding one tube and a wire attached outside the assembly between the ends of each tube. I think it may be a challenge with your method getting the springs into the tubes. But good luck. I think I adjusted the spring tension by curling the springs a few turns inside each other.

As you surmised the locking plunger has to find a gap between the spring coils. I do think the design could be improved to make a safer and more reliable locking mechanism.

I also think the release cable is dangerously close to the water pump pulley for modern health and safety. Mind you I have not heard of anyone taking off their fingers groping for the cable.

[Leo Bolter]

Well folks, all that pre-preparing shown in yesterday's post was a bit of a waste of time.

After much trying to get the springs to slide in the tubes without jamming, I eventually had to un-solder the nipples and remove the cable, as I had discovered the tightly wound convolutions at each end of all the springs had need to be lightly ground down to a smaller diameter. The inner tube (the upper one) had been opened out to 13.5 mm by welding a extension onto the new drill that arrived by courier this morning and slowly machining it in my lathe. I retrospect a slightly bigger diameter would have been better, but I had wanted to retain the maximum wall thickness . . . . Another problem was that there was something right at the extreme inside ends of the outer telescoping tubes that was preventing the springs getting right to the ends and also full telescoping to be achieved. This may have been weld or rust flakes that had been caused by the welding. That impediment had to be removed with a specially made "tool". . . Anyway, the springs eventually went into the tubes and the tubes were, by then, possible to be telescoped completely to the lowered position. The latching pin was machined to a more tapered peg at the end so as to help it penetrate the convolutions of the semi-compressed spring.

That was one stay completed . . . so I fitted it to the car and did a test lower and lift. Disappointment reared it's ugly head! . . . There was no apparent/significant difference in weight to be lifted, but there was a loud scaping sound as the springs were compressed and released. Furthermore the latching pin was not as reliable as it had been previously.

I have spent many hours over the last couple of days and presently I've run out of time to complete the second stay . . . . that'll have to wait for another day. I may even revert to how they were!

[Forumadmin]

Leo,
When you compress the assembled stay it should be difficult to do so completely. For safety when doing this have the safety on as I said in a previous post.
Could the springs be moving inside each other or do they not have the correct strength?

[Jack]

Would it be heresy to suggest that we explore modern boot lid struts? It would get around the problem of the wire temptingly close to the spinning pulley, and once up if chosen correctly could avoid the problem of getting eaten by the car when the latches do not engage properly.

Given the problems we had with ours, and the right hand side still not being 100%, this might be something to consider, even if it would alter the under-bonnet appearance pretty significantly. With an appropriate finish they could be disguised a little to a casual observer, and help those who struggle with the heavy bonnet and the potential consequences of getting eaten with a running engine beneath you - we have a wooden stick behind the seat in the SC for exactly this reason.

Jack.

[Leo Bolter]

Keith, thanks for showing an interest.

You said:

Could the springs be moving inside each other

The Joiner prevents any misalignment and threading onto each other . . .

do they not have the correct strength?

* It’s hard for me to comment not having experienced lifting the bonnet of any other Jupiter (let alone one with original springs). I would hope that whoever had the current stocks made used a original for a pattern and “original” strength specifications . . . also, I would say, anything much longer or stronger would be a real struggle to assemble . . . it would be possible but difficult, I think!

The current state of play:
I should mention at the outset that there is a old scuff mark on the paint, which indicates the extent of the telescoping when in the fully down position.

The stay that I consider to be “finished” and working, albeit noisy and not very “strong”, was assembled, and behaves like this.
If the telescoping tubes are put together, large diameter (lower tube) resting on the floor and the smaller diameter one put into it, without any springs, it will drop to the bottom of the larger one . . . as one would expect. In fact it disappears into the tube to be about 1” below the top edge of the outer tube . . . well past the scuffmark. No problems there!

If I hold the tubes in the vice (soft-jaws of course) one at a time, then when I put a spring into each of the tubes, there’s about 8 or 9 inches of spring sticking out.
By putting a long skinny screwdriver down the inside of the exposed spring it can be compressed right into the tube without any trouble and by using a bit of pressure. A small screwdriver is used through the hole in the side to engage with the convolutions of the compressed spring to keep it from popping out again. When the “compression” screwdriver is removed almost all of the spring remains in the tube with just a 1” or so left protruding.

This is done with both tubes and springs.

The outer tube is held horizontally in the vice jaws and the aluminium “joiner” is fitted to one of the springs. The other spring is engaged with the joiner and the two springs are united. Sufficient pressure is put on the “loose” tube and spring to maintain the alignment of the two tubes as they are pushed together - positioned so as the latching holes will eventually line up. At that stage the small retaining screwdriver in the smaller tube’s orifice is removed, as is the one in the latching pin’s hole. Once the smaller tube has entered the larger tube and the two holes lined up, the small screwdriver can be re-inserted to retain everything.

Now, if the assembly is held vertically on the floor and a pad of cloth placed on the top (to protect one's palm!) and pressure is applied, and if the latching screwdriver is removed, the telescoping action can be tested by progressively pressing down. The inner tube goes right down to the old scuffmark . . . luvely jubberly! It makes a loud scrunchy noise as it does so though. But, with the sliding of the spring, some noise is to be expected . . . I’ll just have to get used to it!

The pegs on the latching plungers has been re-machined to have a 5 degree taper with a "ball end" small diameter of about 3/32" to assist it penetrating the spring convolutions. I intend to use a stronger spring behind them too.

* The force needed to fully compress to the scuffmark will tested and will be inserted here (in red) when next I have a stay off the car. Each stay, completely compressed, exerts a force of only about 9 kg !

The fact is that the bonnet MUST be less of a lift now . . . it’s just that it’s not as dramatic as I thought it’d be!

PS Hi Jack.
I just noticed you'd commented about using gas struts . . . a thought I'd had too. They certainly would have advantages, but out here they are horrendously expensive and don't seem to last very well either It may even be possible to find a sufficiently long one that's skinny enough to go within the existing telescopic tubes!

Thanks for your comments . . .

[Jack]

PS Hi Jack.
I just noticed you'd commented about using gas struts . . . a thought I'd had too. They certainly would have advantages, but out here they are horrendously expensive and don't seem to last very well either It may even be possible to find a sufficiently long one that's skinny enough to go within the existing telescopic tubes!

Thanks for your comments . . .

Firstly from your comments above the springs sound about right in strength - ours stuck out about the same, and ended up with two people involved to get it assembled safely. Two pairs of hands were definitely useful.

On the gas struts, the size and strength required seem to be approx £100 each. You'd need two for a Jupiter, but it doesn't sound outrageous. There are also adjustable struts that can be regassed, or companies who will regas an original one - the trick is getting a company that can regas it to factory spec and not overdoing it! I reckon a gas strut should stay within spec for 10 years. You probably could fit the original tubes over a modern gas strut, with both ends attached it would just slide inside the two tubes. Of course you wouldn't need the pull cord, but you could leave it on there for posterity I guess, or perhaps modify to form a locking mechanism.

Jack.

[Forumadmin]

Why not just use some hydraulic rams? Then you can just press a button and raise the bonnet.

Ah yes, another job to do Jack! Fix the bonnet stay....

[Srenner]

Leo:

My struts have a "stabilzer" fitted into the adjoining ends of the inner springs. It is a short section of solid rod matching the i.d. of the spring and has a washer brazed to the center to act as a land for the spring ends. This piece is in at least two sets of struts I have, although not present in a third or the remains of a fourth. An obscure Jowett part or perhaps a later addition?

Cheers,
Scott

[Leo Bolter]

Gidday Scott.

You said:

. . . a "stabilzer" fitted into the adjoining ends of the inner springs.

Sounds familiar, as that's what I came up with early in the saga. I called it a "joiner" in my earlier descriptions, but stabiliser would probably be a more apt name as it prevents the two adjoining spring ends from getting out of alignment.

I think that what you describe is a essential bit of the set-up and probably was used by the factory, but they are easily lost when the stays are dismantled and they may not have even been noticed before they get ejected!. Consequently the stays are now found to not have them in some cases. (I can now confess that I have made four as two have shot across the the garage and out the door until I "wised up" and draped a rag over the junction of the two tubes when dismantling)



I'm still working on my stays to try to get "satisfaction" . . . . so far it seems a long way off!

Cheers.
Leo.

[Leo Bolter]

Anyone want a FREE set of Jupiter bonnet stay springs?

I'm loathe to upset any future sales of the springs from the Spares Scheme, but really, the spring loaded stays (for me) are hopeless . . I've removed the springs and have returned to the situation that has done the job for me for the last 20 years.

When the stays were still containing the springs and off the car, I tested the "lifting power" on my new digital bathroom scales. Each stay exerted a measly 9 kg (if I'm generous!) when fully compressed and of course this diminishes as the stays extend . . . then there's the poor leverage situation working with the bonnet weight, caused by where they are mounted . . .

Tomorrow my car is off to be delivered to Robin Simpson who will drive it to the National Rally, so I decreed that "enough was enough" . . . . and I don't think I'll bother with further attempts.

[Forumadmin]

I know the feeling. I do not want to recall the amount of time we spent on trying to refurbish them. However, we will persevere and let you know if there are any secrets at making them useful and reliable.

[Jack]

10 months down the road, and we still have a temperamental drivers side strut. It just about clicks up, but cannot be relied upon when engine is running for someone to go under there without someone holding the bonnet or some kind of stay used as a backup.

Has anyone solved this problem, or indeed does anyone know of a strut or two for sale anywhere? Increasingly considering the gas strut options - with the tailgates on many cars becoming heavier I wonder if we can find a strut with the right amount of travel and a close match on force to lift the bonnet without too much effort. Amy's car will never be a concours original, and concerns over driving alone and being trapped by a dropping bonnet are probably outweighed by fairly minor loss of originality that could easily be disguised.

With diagram below it seems that there will be a strut to fit, but at what cost. Something with the kind of travel and force we would need for a Jupiter is looking increasingly like £80+



Jack.

[Chris Spencer]

Jack - Surely if you find the length of strut required - its then a quick visit to the local breakers yard - most modern vehicles have gas struts both on the tailgates and bonnets - if look at the size & weight of the tailgates on some of the van / mpv's there is going to be something that fits the bill - I would have thought that you could sort this for £30ish using this route - its certainly what I shall be doing once I get around to my Jupe Bitza project