67 replies to this topic

[wot179]

http://en.wikipedia....ndard_Whitworth

[wot179]

I like this bit.

British Morris and MG engines from 1923 to 1955 were built using metric threads but with bolt heads and nuts dimensioned for Whitworth spanners (wrenches) and sockets.^[5] The background for this was that the engines were produced using machine tools of a previously French-owned company that was set up for metric production; for the average British motorist to be able to service his car, the bolt heads had to fit imperial-sized spanners.

[wot179]

Gedore is good gear.

Post some pics.

[Dr Terry]

I'm a fitter and turner too, and did my apprenticeship on fixed plant that was almost entirely Whitworth. And in some industries Whitworth fasteners are still pretty common. Whitworth spanners generally have two markings for each size - for example a spanner that fits a 5/8" bolt (thread size) will be marked 11/16" Whit and 5/8" BS. The BS size is always one step smaller than the Whitworth or BSW size. Eg. 3/8" BSW, 5/16" BS, or 1/2" Whit, 7/16" BS.

The original Whitworth standard used the bigger hex size, though it's very rare to come across such old stuff now. Then during the material shortages of WW2 a new British Standard was established that reduced the hex size by one step to reduce steel consumption. This is the BS size on the spanners.

This guy knows his sh!t.

Dr Terry

[bryanw]

this is why I carry an adjustable wrench, or was that spanner, shifter? and for when I round it off, I use my adjustable footprints, but not vise grips, unless the bolt falls out of my footprints while rattling round my tool box.
I have most sizes, the ones not lost!, but my toolbox is just to heavy, so just sits there. And grab a shifter.

wasn't it the vk that had half imperial, half metric? like the uc started getting some metric?

what about discuss threads?
unf unc imperial metric metric fine,std,course gas threads, plumbing threads, dinn? double dinn? really no end to it.

or why does the tap set have 7mm in it?
why do we call a panel van a "PANO" wtf is that?

[TerrA LX]

wasn't it the vk that had half imperial, half metric? like the uc started getting some metric?

I think you will find that all the body bolts etc went to metric around 1980 but the drive train (or is that power train) engine/motor etc stayed imperial right upto 1999. not sure what the LS engines are, they don't interest me.

[Dr Terry]

can he or anyone explain how the systems apply to the socket I have posted photos of in post 32?

I've read many of those links & none of them explain the derivation of the Whitworth hex size very well (if at all).

The way I was taught, was that the original standard sized the hexagon at 1.75 times the thread diameter. That means that a bolt with a 3/4" thread diameter will have a 1.3125" A/F hex. This would be the WHIT hex size.

Many of those links mention the downsizing of the hex standard around WWII. What is not explained very well is that all they did was to use the next hex size down (usually 1/16" down), so the new hex standard for a 3/4" bolt had the head from a 11/16" in the old standard, making it 1.203". This would then be the BS hex size.

Dr Terry.

[Dr Terry]

I think you will find that all the body bolts etc went to metric around 1980 but the drive train (or is that power train) engine/motor etc stayed imperial right upto 1999. not sure what the LS engines are, they don't interest me.

That's correct, basically Commodore bodies were metric from day 1, that's how they were designed in Germany. At the same time however all of the existing driveline bits were imperial, that's how they were designed.

Even when you get to VL, the entire bodywork is metric & the engine & gearbox is Japanese (metric) but there are still a few imperial bits. I believe that BW diff was essentially still imperial.

Dr Terry

[bryanw]

And that's why I should be banned from posting after drinking to much, interesting thread though

[TerrA LX]

That's correct, basically Commodore bodies were metric from day 1, that's how they were designed in Germany. At the same time however all of the existing driveline bits were imperial, that's how they were designed.

Even when you get to VL, the entire bodywork is metric & the engine & gearbox is Japanese (metric) but there are still a few imperial bits. I believe that BW diff was essentially still imperial.

Dr Terry

Agree, but if I may, the Holden motor was dropped from the line altogether in 1986 in favour of the Japanese RB series engine/gearbox as a stopgap till Holden got their act together for the introduction of unleaded (government enforced deadline of 1st Jan 1986) as the old faithful 202 just wasn't upto the task but there was soo much public backlash over the death of the Holden V8 option (My favourite motor) that there was a public campaign "V8s 'til 98" that saw the reintroduction of the Holden V8 to the VL range in October1986 (and the reintroduction of the imperial system).

[S pack]

to throw a spanner in the works.........there's quite a few imperial bolts left on the 3.8L v6(which they've sold quite a few of)j

Probably because it is basically an American design engine containing parts made in Canada.
The bolt threads might be UNC, UNF etc but the hex heads would be imperial A.F.

[TerrA LX]

Probably because it is basically an American design engine containing parts made in Canada.
The bolt threads might be UNC, UNF etc but the hex heads would be imperial A.F.

So would that be classed as a metric or imperial bolt?
There are some bolts on second generation commodores that i can never seen to get a snug fit with either metric of A/F sockets.

[S pack]

So would that be classed as a metric or imperial bolt?
There are some bolts on second generation commodores that i can never seen to get a snug fit with either metric of A/F sockets.

AFAIK the American thread sizes are imperial not Metric. However they are not exactly the same as the British Whitworth thread but in most cases they are close enough for the them to interchange.

I found it impossible to find a socket (metric or imperial) to fit correctly on the rocker cover bolts on our Ecotec V6, so I don't know what 's going on with that one yet.

Edited by S pack, 22 October 2012 - 11:15 PM.

[rodomo]

Whitworth and UNC threads are the same pitch and diameter up to a certain size. (7/16" rings a bell?) The only difference being the shape of the thread.

Also, buy a good quality brass battery terminal, you know the ones, with the square headed bolt that holds it's self still while you tighten the nut.
In 2012 only spanner that fits that nut properly is 1/4" Whitworth.

[TerrA LX]

^ funny you should say that, 1/4 whitworth is about the only one in my kit, just for those lil odd jobs.

[S pack]

Whitworth and UNC threads are the same pitch and diameter up to a certain size. (7/16" rings a bell?) The only difference being the shape of the thread.

Also, buy a good quality brass battery terminal, you know the ones, with the square headed bolt that holds it's self still while you tighten the nut.
In 2012 only spanner that fits that nut properly is 1/4" Whitworth.

Whitworth is 55 deg thread pitch, UNC is 60 deg.
I know 1/2" is different, one is 12 tpi and the other is 13 tpi.

Did I mention anything about battery terminals?
Looks like I need to get a 1/4" Whitworth socket for those bolts then.

Cheers
Dave.