Wheel Bolts - Mystery Solved - I think!

for those with Series MM sidevalve cars produced between September 1948 and February 1953

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David53
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Wheel Bolts - Mystery Solved - I think!

Postby David53 » Sat Nov 06, 2010 10:33 am

I have been having lots of fun getting confused about the correct wheel bolts for my car. I have an ealry Series II which has MM style combined hub/drums. With the help of ESM I think I have solved the question...

There were three Part Numbers for the hubs. The part number is stamped on the face of the drum. So if you check the part number stamped on the drum you can determine which thread it should be:

Part Number 101845 (UNF) = car commencing no 501
Part Number 139285 (UNF) substituted at Car 31790 (bearing diameter size enlarged)
Part Number 183061 (BSF) substituted at Car 131858

In summary:

Beginning of MM manufacture up to Car 131858 = UNF
Car 131858 (MM) to Car 228266 (Series II) = BSF
Car 228267 (Series II) Switched to studs and wheel nuts.

I do have one question. Before I worked this out I have used BSF Bolts in my UNF Drums and tightened them - they were very stiff but I put this down to the drums being new. I have clearly used the wrong bolt in these hubs. Do you think I will have damaged the hub itself, or is it more likely the bolt will have become damaged? ie: Which is stronger - the cast iron hub or the steel bolt?
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David
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1953 Ser II Empire Green

katy
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Re: Wheel Bolts - Mystery Solved - I think!

Postby katy » Sat Nov 06, 2010 2:42 pm

Are you sure that the hub is cast iron?
I think it highly unlikely that they would have used cast iron in them days, more likely cast steel or steel forging.
Somebody correct me if I'm wrong.
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MarkyB
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Re: Wheel Bolts - Mystery Solved - I think!

Postby MarkyB » Sat Nov 06, 2010 8:17 pm

I've got a feeling that the thread pitch is the same with UNF and BSF but that there are differences in the shape of the threads themselves.
One is pointed at the top the other is rounded.
A quick search didn't bring up a direct comparison, but I don't think it's the end of the world to have mixed them up.

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mike.perry
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Re: Wheel Bolts - Mystery Solved - I think!

Postby mike.perry » Sat Nov 06, 2010 11:29 pm

I have to disagree. The first hubs had 18 TPI pitch bolts, BSF, and the later hubs had 20 TPI bolts, UNF. What I have not identified is the changeover point as there seems to be a disagreement between the Service Parts List and my collection.
I will now identify the parts with photos[frame]Image[/frame]
This is the first hub as fitted to SMM 584. It has 18 TPI (BSF) bolts with 3/8 Whit heads. I do not have the part no, I will try to find out tomorrow[frame]Image[/frame]
This hub has part no. 101845 cast on it. The grease cap fits over the centre like a milk bottle top and the bolt size on the one shown is 20 TPI (UNF)[frame]Image[/frame]
This hub has part no.139285 cast on it. The grease cap fits inside the centre and the bolt size is 20 TPI. The hubs on my 1952 MM have been fitted with 20 TPI studs and 3/4 A/F wheel nuts.[frame]Image[/frame]
20 TPI bolt[frame]Image[/frame]
Series MM wheel bolt 20 TPI, 5/8 A/F head.......... Series 11 wheel bolt 20 TPI, 3/8 Whit head[frame][img]



Two questions remain, what is the part no for the 1st hubs and does anyone have an example of hub no 183061 as listed in the parts book. Unfortunately the wheel bolts do not appear to be listed.
I have complete faith in Graham Holt's article on the Series MM website, As a retired design draughtsman he has a thorough knowledge of thread designs and used several references in writing his notes
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katy
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Re: Wheel Bolts - Mystery Solved - I think!

Postby katy » Sun Nov 07, 2010 2:05 am

The wheel bolts are listed on page P.1 of the service parts list as part # 102436

Methinks that the #s cast in the drums may be casting numbers or factory numbers only and not necessarily part #s.

We have this on the Model T Ford parts, where #s on the parts are factory #s and not actual part #s.
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Re: Wheel Bolts - Mystery Solved - I think!

Postby mike.perry » Sun Nov 07, 2010 10:02 am

Thanks Katy. P. 37, 127923 from 501 to 131858 (RHD). 102436 from 131858 to 184760 (Original Morris Minor).
So 127923 is BSF with 3/8 Whit head, 102436 is UNF with 5/8 A/F head. From 184760 to 228267 UNF bolts with 3/8 Whit heads were fitted. After 228267 studs and nuts were fitted except Travellers which were fitted with studs from introduction.
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Re: Wheel Bolts - Mystery Solved - I think!

Postby katy » Sun Nov 07, 2010 5:36 pm

Mike, what material are those 1 piece hub and drums made from?
They look like cast iron, but do they have a steel insert(s) for the bolt threads?
TIA, Ken
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Re: Wheel Bolts - Mystery Solved - I think!

Postby mike.perry » Sun Nov 07, 2010 11:05 pm

The thought that they had been re threaded had occured to me but the ones shown are part of a random collection of front hubs from different sources and I find it highly unlikely that they have all been re threaded including the hubs on my car. There are no signs of helicoil inserts.
I have several sets of rear hubs which all have UNF bolts except for one pair which have BSF threads. I will try to identify the part nos
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Re: Wheel Bolts - Mystery Solved - I think!

Postby David53 » Tue Nov 09, 2010 10:47 am

OK, well now I am a little confused again!!

The hubs I have here are all 139285. According to Chris at ESM these hubs are definitely a UNF Thread. Here are the old hubs from my Series II:

Image

Here are the bolts purchased from ESM which are described as being BSF. They do not fit into the 139285 Hubs:

Image

And here they are next to the original bolts from the car which DO fit into the 139285 Hubs:

Image

The BSF bolts do seem to be "coarser" than the original ones which I am presuming are UNF.

If ESM's sequence of part numbers is correct, and the 139285 Hub is indeed UNF then it follows that the later hub 183061 would be BSF. 183061 is definitely the latest of the combined hubs, as my original Series II parts book lists this number as the hub for the series II (and therefore later MM's)

So......This would mean Mike that there are actually FOUR part numbers for the combined hub/drums!!! Going by your pictures:

First Pic = Unknown Part Number. This hub look very different from all the later ones. As you say, it is BSF
Second Pic = 101845. This is UNF.
Third Pic = 139285, also UNF. (Wheel bolts the same, but bearing size and grease cap changed)

And finally there is 183061, fitted to the last of the MM's and the first of the Series II. At this change they went back to BSF again. These are the bolts I purchased which are correctly described by ESM as "MM and series II"

I still can't quite tee all this up with Graham's findings....so as I say - still confused!!!

I have now ordered some UNF bolts from ESM and am going out tomorrow to buy a thread gauge!
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David
Sydney, Australia
1953 Ser II Empire Green

katy
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Re: Wheel Bolts - Mystery Solved - I think!

Postby katy » Tue Nov 09, 2010 3:29 pm

3/8" UNF are 24TPI, 3/8" BSF are 20 TPI
Also note that the thread angles are different, UNF (and UNC) use 60* threads, BSF (and Whitworth) use 55*
Plus the fact that UNF and UNC threads are sharp top and bottom, whereas BSF and Whitworth threads are rounded top and bottom.
HTH, Ken
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Re: Wheel Bolts - Mystery Solved - I think!

Postby MarkyB » Tue Nov 09, 2010 6:54 pm

Thanks Katy, that's what I was trying to say without having the details, based on the fact that the wrong bolt fitted without completely wrecking the threads.

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Re: Wheel Bolts - Mystery Solved - I think!

Postby Dean » Wed Nov 10, 2010 10:31 pm

I originally bought BSF and they wouldn't fit.. all the suppliers told me this is the size I should have. I then bought just the one UNF bolt and in it went lovely and snuggly. I think your car David was made just before mine (I remember us having a PM conversation), so I'll guess you will have UNF too
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David53
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Re: Wheel Bolts - Mystery Solved - I think!

Postby David53 » Thu Nov 11, 2010 7:31 am

Hi Dean, yes it's very confusing! I have ordered a set of UNF from ESM and have purchased a thread gauge so one way or the other I'll have the right bolts. But there is still some mystery about the hubs and which was changed when....

How's your car going?
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David
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mike.perry
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Re: Wheel Bolts - Mystery Solved - I think!

Postby mike.perry » Thu Nov 11, 2010 9:32 am

Now to add even more confusion, I have been informed that the 1st hubs in the photos also have the part no 101845 and are BSF threaded.
The bolt threads are 7/16 BSF = 18 TPI and 7/16 UNF = 20 TPI. You will need an imperial thread gauge, not a metric one.
If anyone has any different part no hubs or anything with BSF bolts then I would like to hear from them.
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Re: Wheel Bolts - Mystery Solved - I think!

Postby Scott » Fri Nov 12, 2010 3:05 am

mike.perry wrote:[frame]Image[/frame]
Aha - my car has one of those & I've been looking for a 2nd one for the past 20 odd years. I have never seen another one until now.


Are they commonish in the UK?
Scott

[url=http://img133.imageshack.us/img133/523/bo16vy.jpg]1948 Series MM[/url]
[url=http://img133.imageshack.us/img133/2484/dcp001046qp.jpg]1962 1000[/url]
[url=http://img207.imageshack.us/img207/9625/19705bp.jpg]1970 1000[/url]
[url=http://img137.imageshack.us/img137/7259/nullabor25ns.jpg]1959 Van[/url]

[url=http://www.morrisdownunder.com/forum/index.php]Aussie Forum[/url]

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Re: Wheel Bolts - Mystery Solved - I think!

Postby mike.perry » Fri Nov 12, 2010 1:33 pm

I will try to investigate how many cars are likely to have the original brake drums, I suspect that the answer is very few. According to the parts book the 1st change was at LHD 12338, RHD 31790.
The owner of SMM 584 has gone to great lengths to track down the correct parts for the car. He has still not got the correct grease caps so if anyone has any spare please let me know..
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Scott
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Re: Wheel Bolts - Mystery Solved - I think!

Postby Scott » Sun Nov 14, 2010 8:56 pm

mike.perry wrote:According to the parts book the 1st change was at LHD 12338, RHD 31790.
I have a sneaking suspicion that this might have been the point in drum/hub where it changed to the push in grease cap.

I have seen a couple of other early cars locally but have yet to see another early, early drum/hub in the flesh.
Scott

[url=http://img133.imageshack.us/img133/523/bo16vy.jpg]1948 Series MM[/url]
[url=http://img133.imageshack.us/img133/2484/dcp001046qp.jpg]1962 1000[/url]
[url=http://img207.imageshack.us/img207/9625/19705bp.jpg]1970 1000[/url]
[url=http://img137.imageshack.us/img137/7259/nullabor25ns.jpg]1959 Van[/url]

[url=http://www.morrisdownunder.com/forum/index.php]Aussie Forum[/url]

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Re: Wheel Bolts - Mystery Solved - I think!

Postby markattard » Tue Mar 06, 2018 11:02 pm

may I please reopen this discussion!!

some time ago i purchased some wheel bolts for my 1953 split screen morris minor from esm
http://www.morrisminorspares.com/wheels ... ii-p831451

my car no 202554 (attached pic of tally plate)

It seems like my car uses bolts as those shown in the bolt pic on top (green paint) not the ones below that i purchased.

could someone advice which thread is on my bolt please? and hence which one is on the other bolt?
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bolts.jpg
bolts.jpg (84.33 KiB) Viewed 616 times

philthehill
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Re: Wheel Bolts - Mystery Solved - I think!

Postby philthehill » Wed Mar 07, 2018 6:50 am

The early BMC wksp manual had a very good section on the identification of Wheel nuts. Pages 37720 issue 2 & 35406 issue 2.

The early threads were ANF which are not marked with any identification.

Later UNF nuts are identified by a notch cut into the side of the head of the nut or the nut had a platform head.

There was an interim period (Nuffield Vehicles/Components) before UNF was adopted as standard of ANF nuts having the notch or platform head so can be confusing. ANF & UNF are interchangeable but BSF (or any other thread) threaded wheel nuts should not be used.


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Re: Wheel Bolts - Mystery Solved - I think!

Postby markattard » Wed Mar 07, 2018 8:02 am

thanks!! I guess mine are unf then from the look of it i'll ask ESM if they could replace the purchased bolts with the other type, hopefully there are only 2 types!!!


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