A TR7 16V
-
Posts
157 -
Joined
-
Last visited
Content Type
Profiles
Forums
Blogs
Gallery
Downloads
Store
Events
Posts posted by A TR7 16V
-
-
@JohnD: Viz "PS You don't "Weigh" any number of newtons - it's a force, not a mass."
I accept that the use of the term "weight" in any context of SI units is problematic, and would not, for my own part, have introduced the term. But it already having been invited to the party, I felt I had to at least acknowledge its presence. And I didn't think anyone thought that weight and mass were the same thing.
By definition: "In science and engineering, the weight of an object, is the force acting on the object due to acceleration or gravity". The SI unit of force is the newton. Hence, in the context of any description in SI units, the property of weight has to be denoted in newtons. There are plenty of websites, from the BBC on, that state clearly that weight is measured in newtons - do a google.
By argument: If mass does not change with acceleration, and weight does, then weight cannot be a synonym for mass or measured in kg. If a 70 kg body goes to the moon, it still has a mass of 70 kg, but in the Moon's gravity (1.62 m/s2), it weighs 1/6 (1.62/9.81) of what it weighed on earth. So, to say it has a mass of 70 kilograms, but it only weighs 11.6 kilograms shows the nonsense in using the SI unit of the kilogram for weight; especially where acceleration is not fixed at 9.81 m/s2. Because, if you change acceleration, the force experienced/exerted by the unchanging mass, measured in newtons, does indeed change. So, the only SI unit in which weight can be measured, is the newton.
Outside the System International, and in those shops where gravity is a relatively constant 9.81 m/s2, one might use the unit of kilogram-force, (the force on one kilogram in a field of acceleration of 9.80665 m/s2) and abbreviate that to kilogram for convenience. But that unit is deprecated by the SI. So, in a context of SI units, the newton is it.
Graham
-
While you are correct that I was a bit lax in use of terms and capitalization of units, I wasn't expecting an actual peer review. In my defence, I did remember, correctly, that the SI symbol is N, not n, its origin, Newton, being a proper noun, and erroneously retained that capitalization.
But the point remains that 2.73 g is not a great deal of acceleration. But I stand by the fact that it's the shock, or jerk, that really matters in that context.
Moreover, you do not address the point I made, that there is no way on this earth or Fuller's that a 70 kg body would "weigh" anything like 14,000 kg at 2.73 g, i.e. decelerating at 26.8224 m/s^2 from 60 mph in 1 second. At that deceleration, a 70 kg body experiences the same deceleration force that a 191 kg body experiences as a downforce at 1g. As I said, to "weigh" 14,000 kg with a mass of 70 kg, you have to decelerate at something like 200 g.
Your error seems to have been that you divided the force on the 70 kg body decelerating at 2.73 g, i.e. 1890 N, by the force of 1 g on 1 kg, i.e. "just under 10 [9.81] newtons", then multiplied that by 70 to get (1890/9.81*70=) 13486.2, and rounded that up to "nearly 14000 kg". Whereas, the correct calculation is simply 70 * 26.8224 / 9.81 giving an equivalent 'weight' of 191 kg. I did use the rounded down value for the deceleration of 2.73 g, to give 191.1 kg; where, if you do use the more exact 26.8224/9.81, you do get 191.3 kg.
Graham
-
On 22/04/2024 at 10:42, JohnD said:
You trust your life to "old but good condition" seatbelts, johnny. Bye, bye, johnny.
I did fit to new seat belts, in my Silverback. I'm still here.
Force = Mass x acceleration. Stop in 1 second from 60 and that Force is 1890 newtons
[60-0mph/1 second = 26.8224 m/s^2
70kgs x 27m/s^2 = 1890 newtons]
The force of gravity is just under 10 newtons. So Instead of weighing 70 kgs (I wish), for a second I would weigh nearly 14000kgs. My seat belt/harness (and the rollcage) saved me.
Buy new seat belts, please.
John
The average deceleration of 2.73 * g over the 1 second don't seem like a lot. We put fast jet jockeys through something like 4 times that when turning corners in flight, and that's sustained. The bigger issue for them, is taking an M&B powder (and yes, that is such an old joke).
I suspect what's more significant is the 'jerk', i.e. the rate of change of acceleration or third differential of displacement. Even if you went from 0g to only 2.73g in no time at all, then 1 second later went back from 2.73g to 0g in the same insignificant time, that would be a lot more than a bit uncomfortable... twice over.
Also, "The force of gravity is just under 10 [9.81] Newtons", but on each kilogram, so 686.7 Newtons on 70kg. If you did have a mass of 70kg, and weighed 686.7 Newtons at 1g; then you would still have a mass of 70kg at 2.73g, though you would then weigh 2.73 times as much, i.e. 1890 Newtons; which is the same as the force on a mass of 191.1kg at 1g, and nowhere near the force on 14,000kg at 1g. To mass 70kg and apply a force to what's holding you equivalent to having a mass of 14,000kg at 1g, i.e. 137,340 Newtons, you would need to pull 200g. And that is a lot, even briefly.
-
1
-
-
On 20/04/2024 at 15:16, Colin Lindsay said:
Well that was interesting!! I've had these for years, never really looked at them until just now. I had assumed they were new unused, just missing the common centre connector but there is light rust round the brackets and one slight pull on the outer edge, not quite fraying. The fitting kit has never been used and has a NOS bracket for the centre tunnel clip. I doubt the rust happened in storage but they've had very light usage. First time they've been out of the box in my garage, and that's got to be over 20 years on the shelf.
Not the ones I was thinking of. But the extensions with the plastic sleeves over them are interesting - I've added a set of those to the inertia reel belts in the Dolomite, so they plug into one of the centre blocks. But the one you show doesn't look like it's better than mine:
My 1973 black and yellow Sprint (#2065 of the first batch of 2000) has a later interior fitted by a PO; I'm keeping the seats with headrests whatever else I do. It worries me driving the Herald, that it has none. I have some leather effect Dolomite seats with head rests, but one of the seat pan covers is too far gone, and I'm struggling to find a way to get it fixed at a resonable price.
As to old seatbelts: I trust the material (assuming it's in good condition, just old) more than I trust any of the mountings to the bodywork, including those for the seats.
-
Hi Colin,
Which dolomite belts are these? Are they the gray coarse-weave type that go in the common centre block with the red buttons (done all the jokes about the actor, thanks). A pic of the buckle ends would be good.
Graham
-
Only a few years later:
Here's a 44D4 I've removed the vacuum advance unit from. What I wonder about Peter T's one is, how the plate the advance unit normally moves is held fixed? If you just take the advance unit off and blank the hole with one of these £4 plates, it would flop about massively. I've a vague memory that if you use a longer setscrew to hold the points plate down, it jams the moving plate against the fixed plate. Or perhaps the plate from a 43D fits.
So, as you can probably see, I've attached a long set screw to the pin and put a knurled nut on it, so I can change the advance without slackening the bolts holding the distributor to the block. There's a strongish coil spring on that setscrew, to hold it all tight. Gives about 20 degrees of adjustment, about 1 degree per turn.
It only fits under one of the points plates I have, one with a wide slot for the pin to move around. The one I have with a narrow slot pushes the setscrew down, so the spring fouls the tops of the mechanical advance mech pins. It seems a little odd that the plates are different, as they are both from 44D4 A's. But the trouble is Lucas...
That's a rotor arm from a 25D4 Herald dizzy, BTW. Needed it because the 45D electronic ignition unit fouls the normal 44D4 one and the 45D one is too long a reach. The mod to the advance would work with points and a std rotor arm as well.
I will be fitting it as soon as I can expect the rain to hold off long enough.
-
I've got a 13/60 one with no extra holes in it. But it's been re-varnished by a PO, and they may have gone through the veneer here and there. Also the glovebox lid don't match. So it may be a start if you're up for re-veneering one.
It's no use to me so just postage or free collect from St Annes, (too) near Blackpool.
Graham
-
Had another inside door handle brake on the Herald the other day. And while I turned it round 90 degrees to use the other set of holes, I found I didn't like it that way. So I bought a pair off eBay from ANG.
But the odd thing I did note is that they sell them with and without the plastic escutcheons, with the ones without being a few pence more expensive than the ones with. So I bought the ones with.
Interestingly, I did need the escutcheons, as the outside diameter of the bit of the new handle that goes through and the hole in the escutcheon is 16.25mm, where the old ones were 15mm. Hence, the new handles don't fit in the old escutcheons. Moreover, I reckon that if you file the holes out to take the new handles, the walls of the old escutcheons will a bit thin to hold the pin through the handle and drive shaft. I assume filing the new handles down to fit the old escutcheons is a bad idea: too much work and may weaken them.
I mention all that in case ANG spot the error and drop the price on the ones without or up that for the ones with escutcheons.
The other small problem I had was that one of the holes the pin should go through was a bit too small and I could get it through. The thing was that I hadn't checked the pin in the holes in the handle first, and trying to get it to fit in situ when the hole was too small was more than a bit annoying: it's a fiddly job in the first place and that problem caused a certain amount of blue air. I could have gone and got a drill, but as the pin went through the other way far enough to hold, narrow end of the pin into the driveshaft side of the smaller of the two holes, I just did that.
Anyway, with the new escutcheons and the pin in the way it fits, they seem fine – a slightly tight fit on the square shaft, but I don't see that as a bad thing.
Graham
-
6 hours ago, Colin Lindsay said:
If you've ever tried it, driving at night with no instruments gives a very good view of the road ahead with no glare from inside the car, and the instrument lights don't annoy your eyes when you're looking straight ahead and they're just hitting the edges of your receptors where they're more sensitive (the way you look at stars by looking to one side, not directly at them). Modern cars such as Saabs have a 'night' setting whereby the instrument lights extinguish just leaving you a portion of the speedo illuminated.
Nope, never had that problem or the desire to avoid seeing the instruments. Indeed, I was taught to continually look down at the instruments every few 10s of seconds or so while driving. Having them off while driving in the dark is dangerous madness in my book.
Turning them down a bit, despite the cost of the rheostat, might make some sense. But I've had enough cars with adjustable instrument lighting and never set that anywhere but full. The 73 Doly Sprint don't even have that, just on with the sides. Mind you I don't know if the early 1850 it's based on had such adjustment: that being a proper production car, not one where they made exactly enough (to within less than 100 in 73) to get and keep the FIA Group 1 homologation they needed for the British Saloon Car Championship becoming a Group 1a series from 1974. The "a" in that is another interesting subject.
-
4 hours ago, NonMember said:
That's not how the factory wired it. The original wiring has the connections on the master light switch the other way round, so you can drive with side-lights (or even main beam) but no instrument lights.
Why?
I'm sure that will be contentious, but I really don't see the point of separating sides and interiors either way. And, from what's said about later Spitfires, it sounds like Triumph/BL agreed.
What I have, even if it's wrong from the originality perspective (but still reversible) makes sense except for the third, side lights only, position of the column switch which replicates the first position out on the master. And even while that third position is currently pointless, I can see how I might use it if I fitted front (or front and rear) fogs.
In that case I would power the sides (and instruments) and the mains and dips (optionally through the column switch) off the first and second positions of the master and the fogs off the second only. I'd want another warning light for them though - I so hate those twits (or spelt with a different vowel) who drive on rear fogs cos it was a bit misty earlier in the year.
Graham
-
1
-
-
I just bought a LHD decal for the indicators and a RHD one for the lights - I had to keep the RH cowl on the right as I have an overdrive switch on the column. Cost more than £2.50 though.
What I would like to do is to put a two axis switch on the left side, up and down for turn lights; forward and back for mains and dip; and a spring biased pull for flash. But I can't even work out how to put a standard column light switch on the left in a spare overdrive cowl I have. If I could to that, I would then modify the original column light switch so mains gave normal wipers, dip gave intermittent and the biased pull powered an electric wash pump. The old wash switch then could be replaced with a control pot for the intermittent wipe speed.
Graham
-
On 01/10/2021 at 18:12, Prawnabie said:
when I flashed the main beam, all the sidelights came on too! I spent hours checking the wiring and switches etc and noticed it only happens when the master light switch in the dash is off and the column stalk is in the main beam position.
I didn't think that mine did that, and I checked and they don't. I worked out that's because a PO connected the sides to the same first position output of the master light switch as the instruments, so the side lights come on at the first pull of the master switch, and only connect to the feed into the column switch when the master is all the way out.
That the side lights should always be on with the instrument lights seemed so right and logical to me, that I never questioned it. And as I've never ever wanted to drive with just the instruments lights on and can't imagine why I ever would. I have no intention of "correcting" it.
Graham
-
4 hours ago, Pete Lewis said:
its easy enough to swap pushrods so long as the one you add is round holes not pre worn
Pete
I still want to know if swapping the master cylinder and keeping the push rod will move the pedal up or down. And the holes in mine are a bit worn - the 8mm clevis I think got sold is only tight in the pedal arm, and quite slack in the fork. I do see that replacement rods with forks are available, but I think I want a slightly bigger bore. However, I'm still worrying a bit that 3/4" is a more bigger than I want.
I got a reply on the 5/16 UNF thread fork to fit the LR 0.75" cylinder, and it takes and comes with an 8mm clevis pin. I really do like the look of the pin clip it comes with. I feel like the R clip on the one I got to replace the one in the car sticks out too far and might split the boot in time.
Graham
-
Think that this one might be better:
https://www.ebay.co.uk/itm/224547870126?hash=item34481895ae:g:g28AAOSwWl5dwqu-
I'll ask them what the pin diameter is, as that's not given in the listing.
Graham
-
1
-
-
4 minutes ago, Nick Jones said:
Just swap the push-rod from your original master. 1 circlip, takes under a minute…..
Nick
But then I lose the ability to adjust the pedal height. Will it naturally come to the same height with the same rod in a different cylinder?
Graham
-
The last two posts seem to suggest that increasing the pedal force by 1.44 won't be that big an issue.
In which case the next problem is to find a fork with a 5/16th thread? Lots of M8 x 1.25mm pitch.
Don't suppose anybody knows the thread on a Land Rover S2/3 handbrake link?
Graham
-
While I've got some clutch movement back by replacing the pedal, bracket, and clevis pin, I would like to see If I can get just a little more. So I was thinking of a bigger bore master cylinder then the 5/8th (0.625)" one I have in, which will get more slave travel for the same pedal movement, but stiffen the pedal a bit.
Pete Lewis suggested a 3/4"e LR one as a cheap option, which they are. But they don't have the fork for a clevis pin. They aren't expensive either, but I don't know what thread is on the piston pushrod on the LR cylinder. The good thing there is there's an opportunity to use the thread to set the position of the pedal. But I recon that 3/4" bore will take 1.44 times the force to move the pedal, but, obviously, 1.44 times as much clutch movement. 1.44 times sounds a fair bit more force, but it's leg work and the pedal is light enough now. So I wondered about a 0.7" bore TR cylinder, which would only take about 1.25 times the force and still give me a bit more clutch movement.
So, has anybody done any such thing and/or got opinions? And if anyone's used the LR one, can they give details of the clevis pin fork I would need and how much heavier the pedal becomes?
Graham
-
Thanks guys.
Graham
-
Just to check the size of thread on the outlet of the master cylinder is 3/8 unf?
Graham
-
I wondered if it would need some heat, but yours just pressed out. I'll give a try, though my vices are more modest than "Record" ones.
Graham
-
1 hour ago, PeteH said:
When I pulled Both the Clutch and Brake pedal/box units out of my "Crate of parts". They where both seized onto the spindle and where rotating on the Flange sides. where they had worn the holes slightly? 1/16"! Oval. I ran some weld into the oval,dressed it back and filed it to a tight fit. Now the pedal works properly again. I am tempted to put a bead of weld on one side to stop it hapening again?. The other option is to "D" the end of the pin and weld a strip over the hole to stop rotation but that will require modifying the pin too. The simple answer might be to drill an oil hole into the pedal, and a squirt of oil, now and again?. I think I like simple?.
Pete
How'd you unseize the pins from the arms?
Graham
-
If you mean STC500100, I see those really are cheap. Will need a fork fitting I see, But even so, that's still cheap. Wonder how much control I get in setting where the pedal sits and goes down to. Is it likely to need a stop on the pedal, or is whatever limits the travel in the cylinder strong enough?
Graham
-
3 hours ago, Pete Lewis said:
there room to mig a washer both sides of the bracket then you just need a nyloc nut to give it a nip
Pete
The issue with welding washers on both sides is the one, I think it was Colin, identified of the pin turning in the bracket rather than or as well as the pedal turning on the pin. But maybe shaketights would do instead of a welded nut and jam nut.
Anyway, the replacement is in now, and I can confirm that, in the 1970 13/60 I have, the brake pedal and it's bracket fit where the clutch pedal should go.
The old set was giving about 5mm of play at the pedal from the wear in the hole for the pin, which is seized in the bush, and another 8 or 10 from the assembly at the joint between the pedal arm and the master cylinder piston rod - a lot of that just from the clevis pin itself (is it meant to wear sacrificially?). The new 5/16th clevis was very tight in the replacement arm, if not so tight in the fork on the end of the rod.
So I think the loss in pedal movement due to slack in the mechanism is less than a 1/4 of what is was. It's enough that, for now, there's no grunting going into reverse.
BTW, has anyone fitted a bigger bore master cylinder, and are there any risks in pushing the slave too far?
Graham
Graham
-
I'm still looking at how I might fix the worn clutch pedal bracket that's in the car.
The replacement bracket and pedal arm do take a 5/8 bolt through the pivot - the unthreaded section of the 5/8ths bolt I have is the same diameter as the pin. i.e. 0.616" not the 0.625" I expected. In which case, a 3-1/4 DIN 931 bolt should have an unthreaded section the right length and can be shortened to the right length of exposed thread. It should have 1.5" of thread and 1.75" unthreaded, but the one I have is threaded 1.8" (like a DIN 931 over 6" should be) and only has 1.4" of unthreaded (so is too short). So a proper DIN 931 3.25" or a 3.5" threaded 1.8" like the one I've got at the moment. I don't think it will matter that the 3-1/4 bolt I have will have 3 or 4 mm of thread inside the bush.
So I'm thinking of getting a 5/8ths thin nut welded on one outside of the bracket, and a 5/8ths washer or maybe 2 welded on the other outside. The bolt can then be screwed in so it's tight on the welded on washer, but doesn't nip the pedal; then locked with a second thin nut jammed on. I am wondering if that needs a shaketight washer between them.
If the bush in the pedal arm is no good after being seized on the pin, that will need replacing. But at least they are available.
Spitfire MKIV complete seatbelts
in Parts Wanted
Posted
I wasn't really looking at the load on the webbing. I think there would be much work to do to get any sort of reasonable estimate for a peak value for that, as I suspect there's a big difference between the average deceleration and the peak, depending on what stops the car and how the forces reacting to it change over the period. I really just wanted to point out the error in the calculation that suggested an average of an effective weight of 14,000 kg, where it should be about a much less remarkable 191 kilograms-force (in none SI) or about 1800 newtons (in SI units).