MG-Cars.info

Welcome to our Site for MG, Triumph and Austin-Healey Car Information.

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG TD TF 1500 - Issue in what wrench size to use

I have been working to develop a complete listing of the fasteners on the TD body and frame.

I have run into a significant issue that I need input on.

We say our cars have whitworth nuts and bolts, but in fact they are mostly BSF. (I believe the only actual whitworth fastener is on the generator adjusting arm.)

Problem comes in that many of the wrenches we use are marked in whitworth and others are marked in BSF (some are marked in both).

There is a one size difference between the two systems.

The lists I have been using are using whitworth wrench sizes. Chris Coopers list is in BSF. My wrench set is BSF, so everything I have been measuring is in BSF.

My concern is I am unsure when you order a bolt if you will get the correct size if we list the Whitworth size. (the parts sellers list their fasteners as BSF)

Here is a chart that compares Whitworth to BSF, Metric and American. https://www.dropbox.com/s/rbpoebrgs8q35y5/Whitworth%20VS%20BSF%20VS%20Metric%20VS%20inches.xlsx?dl=0

It is possible to list the fastener in both Whitworth and BSF on my list, but it may be more confusing.

If we standardize this, it is going to mean some folks wrenches are not going to match our list.



Bruce Cunha

Bruce as bolt thread is BSF, the bolt head will be the appropriate BSF size, so I would think your list should show BSF wrench size
Stuart

ps. Have you looked at the Y type bolt and fastener list on the IMGYTR website?
Stuart Duncan

Bruce - the heads on the BSF bolts are one spanner size smaller for the same Whitworth bolts - i.e. 1/2 Whitworth bolt will have a head that is marked 1/2. The same 1/2 BSF bolt will have a head one size smaller than that of the Whitworth bolt. The set of Whitworth spanners that I have were all marked with the Whitworth sizes, requiring me to remember that the 1/2 BSF bolt has a head that has a head (7/16) one size smaller than the 1/2 Whitworth has a head that requres a 1/2 Whitworth spanner.

I have several sets of Whitworth spanners - the first set was marked with the correct Whitworth heads. I also have a set of Whitworth spanners that are marked with both the Whitworth head and also with the BSF heads. I am not sure if I have a set of spanners marked strictly for BSF heads.

I have to think that the Brits came up with the Whitworth bolt sizes just to confuse the hell out of us colonials.
Cheers,
DW DuBois

When using a BSF bolt use the BSF spanner size as the designator. For the dynamo adjusting bolt I would probably identify it with the BSW designator. You could side note that the BSW accepts the appropriate BSF sized wrench. I think most modern wrenches don’t differentiate the two and only list the BSF equivalent Older quality wrenches such as Snap-on used to have both sizes listed in them. It only served to make my newbie status more confusing when I first started dealing with T-Series cars. It took quite a bit of time to finally get my head wrapped around Brit thread nomenclature. When I first bought my tap and die sets I ended up buying both BSF and BSW sets not understanding what I really needed. But that’s for another conversation. Lol

As a side note to Bruce. It was good to see your chassis progress today. I’m anxious to see it rolling again soon. Let me know what the machining operations will cost me on the sprocket. I’ve got to try and keep the costs out of the stratosphere for my customer.

Bill Chasser
TD-4834
W A Chasser

My set is apparently BSF (no W after the size). They are made in Germany and just say Chrom-Vandium on them.

Stuart. Thanks for the tip on the Y. I will check it to see how it compares.

Dave. That appears to be the point exactly. For example, I asked for the bolt size for the Armstrong shock. The person that answered said it was a 3/8 bolt. He must have used a whitworth wrench. The shock bolts are 5/16 BSF.

I understand why the issue. During WWII when they changed the whitworth head to BSF, the mechanics all had whitworth wrenches. They could still use them.

Think I will just put a note on the list that says If you are using a whitworth wrench, the wrench size will be 1 size larger than the list.

Oh, and Dave. I am not touching the Engine. I think you have got that one covered.
Bruce Cunha

Bruce.
Sorry, but I think you are confusing the issue,forget about head size. All bolts are quoted or ordered by the diameter of the bolt, not the head size. That is, a 3/8 bolt is 3/8(0.3750")in diameter regardless of what thread is on it, whether it is BSF,Whitworth, Americian corse or Americian fine, or what head size is on it.

When Rob Granthan quoted 3/8 bolt for the armstrong shock bolt, that bolt is 3/8 in dia, not 5/16.

When people order bolts, they will get the diameter that they ordered.

Hope this helps.


Regards

Ralph.
R E J Stewart

Ralph, That is not what the suppliers are telling me. IF they list BSF. The size is head size from flat to flat.

As an example. I just ordered philadis nuts from British Fasteners here in the US.

I ordered 1/4 BSF nuts. Nut fits the 1/4 BSF wrench. The diameter of the actual thread is smaller.
Bruce Cunha

Hi Ralph,

Thankyou for clarifying what I stated. I of course was referring to the diameter of the bolts used on the Shock Absorber !

Over here we are all still recovering from our West Coast Eagles fantastic win in the AFL 2018 Grand Final. (the equivalent of the USA Super Bowl winner).

Great to have your TF input again.

Cheers
Rob Grantham
TF3719("Aramis"),TF9177("Athos").
Rob Grantham

Bruce - Look at the Standard Threads and the Wrench Sizes FASTENERS AND WRENCHES ARTICLES FOR T-SERIES MGs: in the Other Tech Articles section of my Web site at: http://userwebs.donobi.net/sufuelpumps/index.html regarding BSF fasteners and Spanner sizes.
Cheers,
DW DuBois


Thanks for that clarification Bruce, but I must say I am surprised about that.
As far as I know if you order a 1/4" nut or bolt in any other part of the world it would be 1/4" in diameter, regardless of what thread form it had on it.

Anyway, best of luck in compiling your list.

Cheers.

Ralph.
R E J Stewart

Bruce -

Sounds like you are closing in on a format for your fastener list. I agree that the wrench size should be BSF plus that a note explaining the relationship between BSF and WW wrenches.

My Rolson 8-pc 12-pt combination wrenches are marked in Whitworth only. My Koken 8-pc 6-pt sockets are marked in Whitworth and in British Standard Fine. So, it's easy to see why some owners can be confused.

Regarding your conversation with suppliers ...
Not sure what you mean by the head size listed by suppliers is from flat to flat. The across-the-flats measurement of a 1/4" BSF nut/hex head is 0.445".

What was the diameter of the threads on the 1/4 BSF nut? How much smaller than 1/4"?

British Tool and Fastener lists nuts and bolts by the diameter of the shank. I didn't see any reference to head size for the nuts and bolts on their website except for thread profile - BSF or Whitworth, which defines the head size. I measured a 1/4" BSF bolt and nut. The diameter of the unthreaded shank was 0.245". The diameter of the threaded section was 0.241". Distance across the flats of the head and nut were 0.441".

>> My suggestion:
Don't trust MG owners to give you the correct fastener size. Ask them to measure the diameter of the bolt. If they can only tell you the wrench size, then ask them to confirm the marking on the wrench.

Thanks for taking on the huge task of updating the MG fastener list.

Lonnie
TF7211


LM Cook

Here is a write-up I found some time ago regarding sizes.

I recently bought an excellent set of BSF taps and dies for $264. it contains 3/16 to 1/2 in. BSF taper and bottoming taps and corresponding dies, and tap handles and die handles (21 pieces). I added 2BA and 4BA taps & dies for the small stuff ($!3.20 die, $6.50 tap). This covers everything except the axles.
try www.britishfastener.com, BSF Tap & Die set Code 4305

The most appropriate set is the BSF (British Standard Fine) in the following sizes: 3/16-32, 1/4-26, 5/16-22, 3/8-20, 7/16-18, 1/2-16. For the smaller sizes you might need 2 BA and 4 BA (British Association). I found for the windshield post bolts that I needed a 5/16-26.



I have had my TD since 1973. I have a set of 5 Whitworth sockets (3/16, 1/4, 5/16, 7,16, 3/8 and 1/2)

4 closed end angle wrenches (1/8 - 3/16, 3/16 - 1/4, 1/4 - 5/16, 5/16 - 3/8

One thin open end 1/4 - 5/16

If you want really good quality Whitworth/BSF tools then
contact SNAP-ON. They still sell sockets and combination
wrenches in Whitworth/ BSF sizes, guaranteed for life.
I have recently purchased such items as the socket that
fits the TD front wheel spindle for example.
These are the best tools made, and they cost as much!!!
They sell a socket set that covers from 4BA thru 0BA and
3/16 BSF (1/8 W) to 5/8 BSF (1/2 W). Larger sizes are available
as separate sockets. (cost like the devil!)
The combination wrench set is invaluable!

The T series body has only British Standard Fine threads (BSF) in the Whitworth pattern (56 degree rounded thread, Not 60 degree pointed thread as in US and ISO Metric threads) The bolt heads are Whitworth sizes and are categorized by the diameter of the bolt, , not the head)

Thus a 1/4 inch BSF bolt is a 1/4 inch in diameter with 26 threads per inch and has a head that is a little larger than 7/16 inch, whereas a US 1/4 in fine thread bolt has 28 TPI and a 7/16 US wrench fit s the head.
The corresponding BSF wrench is marked 1/4 BSF, the Whitworth wrench that fits is marked 3/16 W ( Historical problem).

Similarly, the 5/16 BSF bolt has a larger head and a thread that lies between US Fine and Coarse thread. The corresponding British Coarse thread (Whitworth) is the same as the US Coarse but with the different 56-degree profile. The wrench is marked 5/15 BSF or 1/4 W not 9/16.

The engine and transmission however are very different however as they have French Standard Metric (NOT ISO METRIC) bolts and nuts but with heads that Whitworth wrenches will fit (NOT METRIC OR US) These sizes are a mix of metric coarse and fine thread ( 6 x 1 mm, 8 x 1 mm, 10 x 1.5 mm, 12 x 1.5 mm, etc., but with Whitworth heads)

Late TD's and all TF's have Unified threads on the rear axle (same as US Fine
James Neel

The BSF thread angle is 55 degrees not 56 degrees.

https://britishfasteners.com/threads/bsf.html



Although never mentioned in this post, and just to add confusion the BA thread profile angle is 47.5 degrees.
These are the UK equivalents to the US machine screws #0 through #14, Most BA threads are neither Metric or Imperial. But the 0BA is 6X1 metric screw. All the others reduce both the diameter and pitch by 0.9 for each step.
Thus the 2 BA diameter is 0.9x0.9X6mm= 4.86 mm and the pitch is 0.9X0.9X1mm = 0.81.

I got my TD in 1966. I had no ides what kinds of wrenches to use. If an inch wrench did not fit I used an adjustable.

I was on company business (ITT) in Paignton (STC long gone now) England I think in 1968/1969. On a free Saturday, I got the UK hosting engineers to take me to an "Iron Mongers" and I got a set of box BSW/BSF box wrenches and sockets.

You should have seen the look on the custom officers when I cleared customs at JFK with a brief case full of tools.

One day, in Florida, my son and daughter , 5 and 4 years old came home with a BSF 5/16 Snap-on combination wrench they found in the road. From that point on I was sold on Snap-on.

I got a set of sockets and over the years I have acquired sets of short combinations, long combinations open end, short box and long box wrenches.
The only one I am missing is a long 1/4 BSF combination.

I have probably only used the Short combinations, a few of the open ends, 1/4, 5/16, and 3/8, and a few of the sockets.

I also have a set of BA sockets and a few BS ignition style wrenches from eBay.
I have a daily search of eBay for Snap-on BSF/
ba/Whitworth wrenches.


Jim B
JA Benjamin

Thanks All. What I will do is list shaft size in one column and wrench size (using a BSF wrench) in another.

I will put a note to clarify how a supplier is listing their bolts so correct ones are ordered.
Bruce Cunha

The purist in me wants to keep using the Whitworth bolt sizes since that is the tools that were provided with the car.

In fact the parts manual and workshop manual rarely spell out BSF except in rare cases. These were generally the Philadis/Simmons nuts on the drive shaft and front steering arms. Also interesting was the carriage bolt on the rear leaf spring clamps. There may be a few others but that was my quick pass.

So once Bruce updates his list we will merge it into the website and put some notes in on head and shaft sizes and what they represent. This way purists like me will be happy and those that need to order correct replacements won't be as confused hopefully.
Christopher Couper

Made my first work at purchasing correct nuts and bolts for the TD restoration. It is a bit of a trying process.

You can trust the big suppliers by buying their fastener "Kits" and hope they have the correct bolts/nuts, or you can try to order individual bolts.

If you use the search engine, you can find the BSF bolts/nuts on the Moss site, but I could not find that they had all the correct bolt lengths (at least in the US)

British fasteners (US) had most of them, but 1/8 sizes are missing (I called them and they said that manufacturers for some reason don't like making 1/8 sizes (EG. They have 1 1/4, but not 1 1/8). They also did not have the 5/16 x 7/8, which is one of the more common bolts on the TD frame.

Abingdon Spares has probably the best list. I was able to find all the fasteners I needed for this part of the restoration, but got turned off when the shipping cost was 1/2 the total for the fasteners ($118 in bolt/nut costs and $58 in shipping). That is a bit of a concern in that all of the order would fit into a US postal service prepaid large box, which goes for $18 regardless of the weight.

In the end, I used British Fasteners (they even had Philidas nuts in the correct sizes) for the majority of fasteners and Abingdon for the ones BF did not have.

Our friends in the UK appear to have a bit more choices. There seems to be a number of fastener companies in the UK.
Bruce Cunha

"That is a bit of a concern in that all of the order would fit into a US postal service prepaid large box, which goes for $18 regardless of the weight."

Did you ask them about that?

I wonder how much of a charge they have for "picking" the bolts from the bin?
Christopher Couper

From the AS web site:

"Remember, Abingdon Spares never charges a handling charge, we only charge you what the USPS charges us!"

"Abingdon Spares now offers free shipping on all orders
over $700.00"

(Continental USA only)
James Neel

I just spoke with Ed at Abingdon Spares and suggested that he might want to view this thread.

I also learned that their shipping is not based upon the use of USPS Flat-Rate boxes. (Where weight doesn't matter.)

Bud
Bud Krueger

Just Googled the USPS on Flat-Rate box fees. Seems that I could send a 70 pound Flat-Rate box (small, medium or large) across the USA for the standard fee ($7.20, $13.65 or $18.90). Standard Ground would be $130.51.

Bruce, did you ask A/S about Flat-Rate boxing? Bud
Bud Krueger

I didn't inquire with AS on the shipping. Just used their on-line system. The way I split the order, I saved $40.

Bud. That should be of interest to a lot of us. The large USPS prepaid will fit a lot of smaller parts. I would be interested in why they don't use it.


Back to the issue of wrenches.

I did a lot of reading and found I am mistaken. There is NOT a BSF wrench. All wrenches are Whitworth. The difference is that the Whitworth head size was reduced .

Here is what Moss says on the topic.

"In 1924 it was decided that the heads of the Whitworth bolts were too large, so they were down-sized.

The “new” bolts and nuts were made so that the old tools could still be used, but on different bolts. The old 3/8W wrench now fit the 7/16″ bolt. To enable the tools to be used easily, they are marked with both sizes. The old size, which stands for the diameter of the bolt’s shank, is marked with a “W”. The new size is marked with a “BS”, which stands for the bolt size and consequently the new wrench size. For example, the old 3/8W wrench also fits the “new” 7/16″ bolt, and is therefore also marked “7/16 BS"

So, BSF is a Whitworth thread, it just has a finer pitch meaning more threads per inch. What I thought was BSF on the wrenches is BS. Or the Bolt Size

The heads are all the same until you get below 1/8 and then we move to the BA system, which is based on a Swiss Standard and uses 0 to 22 with the larger the number, the smaller the screw.
Bruce Cunha

Bruce,
I have to disagree on the BS notation.
BS stands for British Standard and was used for all our standard thread forms.
British Standard, Whitworth, Fine, Brass, Cycle and Pipe.
I checked back in my 1928 issue of the Board of Trade Marine Text book to make sure I knew my facts.
All of these threads are used on our cars plus BA and AF and maybe some more I don't know about.
Just remembered the late TF temp gauge is American Pipe but the heater take off next to it is BSP (mix them up at your peril!)
Ray
Ray Lee

sorry, for AF read ANF or "unified"
Ray
Ray Lee

No issue Ray. It just points out the variety of information on this issue. If Moss does not get it correct, that says something.

How does the BS term fit in with the wrench size we use?
Bruce Cunha

Worth checking Wikipedia on this subject Bruce. Good write up on the derivation of the British thread types and also of the tools used on our cars. Ray is spot on with the meaning of BS. https://en.wikipedia.org/wiki/British_Standard_Whitworth. Cheers
Peter TD 5801
P Hehir

If the spanner (wrench) is marked BSW/BSF or W/BSF use the BSF for both Whit and BSF of that shank size.
If just BSF it fits both.
If W or Whit and newish then it fits both BSF and Whit.
If W or Whit and very old and worn it will only fit 1/16" larger in diameter bolt.
Very confusing as I found as a 16 year old apprentice in 1955 where some of the older large head BSW bolt were still in use.
We also had steam traction engines which had some square nuts just to confuse even more.
Ray
Ray Lee

Ray, what manner of wrench did the square bolt heads use?

Jim B.
JA Benjamin

They had just square jaws and different off sets as the square heads limited the amount of turn you could get.
We made up our own "ring" spanners with 8 point star holes to make life easier. When I tell youngsters I worked on steam lorries (trucks) and they were used on the highway I get looks of disbelief.
Ray
Ray Lee

Not one I worked on but a good example.
Ray

Ray Lee

Ray - 2004 we visited friends in Wiltshire. Of course, they took us to see the sights, one of which was a lift pump to transfer water into the canals in the area. The pump that you pictured looked very much like the pump we saw. The eerie thing about that pump, was that it made no noise except for a quiet click at the end of each stroke. Cheers - Dave
DW DuBois

This thread was discussed between 02/10/2018 and 07/10/2018

MG TD TF 1500 index

This thread is from the archives. Join the live MG TD TF 1500 BBS now