Metric studs

[seriesmm_1]

Can anyone tell me why the series mm 918 sidevalve engine has metric studs-head M10 x 1.5 pitch & manifold M8 x 1.0 pitch, nuts & bolts gear box to block again M8 fine
I'm just curious, I'm sure someone knows

[DAVIDMCCULLOUGH]

Originally a French design engine!!

[BLOWNMM]

Hi Guys
The early Morris motors were supplied by the Continental Motor Manufacturing Company of Detroit USA. Continental then decided they no longer wanted to supply motors to Morris so Morris purchased the drawings and tooling from Continental and engaged Hotchkiss to manufacture their motors. Hotchkiss had metric tooling and insisted on using metric threads. However upon the insistence of Morris the metric fastners were to have Whitworth/BSF head and nut sizes. The use of these threads continued until the release of the Series 2 OHV Minor which reverted to UNF/UNC fastners. All 10 mm. and 6 mm. threads are standard ISO metric coarse but all 8 mm. threads are metric fine - 1.0 mm pitch.
Cheers Bob

http://moreg.org.au/wordpress/home-2/ab ... s-engines/

[smithskids]

Spot on sport, I have just changed gearboxes on my sv mm and the gearbox No 18310 is unf threads I had expected it to be bsf. the engines are as you say Metric.

[BLOWNMM]

Hi all
The threads in the side valve gearbox are also metric - definately not UNF. They are mostly 8 mm. The 4 securing the top and the 6 securing the rear extension are 8 mm. fine. The three securing the front bearing retainer are 6 mm. ISO metric coarse ie. 6 mm. X 1 mm. pitch The differential threads are BSF. I'l never understand why Hotchkiss used 8 mm. fine pitch for the threads in the alloy sump and timing cover. All of the Morris 8 and MM motors I have worked on I have used stainless thread inserts.
Cheers Bob

[seriesmm_1]

Thanks for that information Bob, very informative & has satisfied my curiosity

Regards
BrianR

[mike.perry]

On my USHM3 engine I have re tapped the gearbox to sump threads and dynamo mounting threads to 3/8 UNC to avoid the risk of stripping the fine alloy threads

[TvdWerf]

Not only Morris was using the metric 8 fine, but also Massey Ferguson.
When I need bolts and nuts for the M8 fine, I go to the local MF dealer ;)

[smithskids]

This gearbox is definetly unf, the back axle I bought with it is also unf, including the wheel bolts!

[BLOWNMM]

Hi Smithskids
I cannot understand your explanation of UNF threads. The MM split case differential definately had BSF threads. In an amicable attempt to resolve the difference I would like to say that I have worked on 3 Series E gearboxes and am on the 4th MM box. The series E was identical to the MM except for the rear housing which had a different mounting arrangement and a differently shaped gearstick. All had metric threads. The only thing coming to mind is to ask what the material of the box is - ie. cast iron or aluminium alloy, and the diameter and pitch of the drain plug and or filler plug in the top of the box. The answer to this may reveal the solution.
Cheers Bob

[smithskids]

Hello Bob, I've just nipped out to the shed and checked two of the axles. Both are cast iron with steel tubes.The one I bought with the gearbox is No 102118 casting number on the axle casing and the threads are unf. Axle thread is 5/8 X18 tpi . axle No is 19956 8/43 5.375:1.
The original axle from my MM is No95046 axle casting No is 101505RR. Axle thread is 5/8 X14 bsf.ratio 9/41. 4.55:1. Both filler plugs are 3/4 bsp. and the drain plugs are 1/4 bsp. Where the axle and gear box came from in the beginning I don't know. The old guy I bought them from just said they were from an early MM he had scrapped. I have a 1935 series one since 1970 and I have had this MM tourer since1976. I sold a series E g,box to a friend of mine recently and was wishing I hadn't but the ratios are lower than the MM box except 4th which is 1:1. I will try for some photos when the weather clears up. I have asked questions about this axle and box before but no one has come up with any answers yet. The Brake drums are exactly the same as my MM ones except the bolts are unf, they came with the axle. Cheers Bob .Regards Iain.

[BLOWNMM]

Hello Iain
The plot is beginning to thicken. My Morris 8 Series E Nuffield workshop manual gives gearbox ratios as 1st/reverse 3.95:1,
2nd. 2.3:1, 3rd 1.54:1 top 1:1. These ratios are the exact same as those given in my Nuffield MORRIS MINOR Series MM and
Series11 workshop manual. The gearbox internals are interchangeable from the first Series E in 1939 to the last MM. There are numbers stamped on the top front left of the machined surface that the top bolts to. Two of mine are 37232 and 44654. When I asked for the drain or filler plug thread I meant on the gearbox. They both should be 30.00 mm. dia. X 2.0 mm. pitch. What material is the gearbox made from - cast iron or aluminium alloy. I am very curious to get to the bottom of this. The website for the Series MM Register of the MMOC lists various axle and wheel bolt threads. Would love to see pics of the gearbox and diff. Cheers for now Regards Bob

[mike.perry]

Read http://seriesmm.mmoc.org.uk Technical info, Front Suspension, Stub Axle and Wheel Bolt Threads

[BLOWNMM]

Hi Iain
Have attached some pics of my spare box. All of the nuts are 8 mm> X 1 mm. with a 13 mm. head size. This is better as the head is smaller and makes the securing of the six rear nuts easier in the cramped space. The front three are 6 mm. cap screws.
You may also notice a new front cover machined to accept a lip type oil seal. The rear housing is also boored to fit a lip seal and the uni joint flange has the scroll machined off to suit the seal.
Cheers Bob

[colin addison]

Hotchkiss were a French company and opened a subsidiary in Coventry in the First World War, ref google!
Morris bought the Hotchkiss factory in Coventry in 1923. Hotchkiss - French, hence metric threads. The cylinder head threads are 'metric coarse' but there are also a lot of 'metric fine' threads on our cars, the conrod bottom bolts are fine, along with the gear knob! and probably others.
Colin

[smithskids]

Hi Bob, you are correct with the gearbox ratios, the book I quoted them from INCLUDED the diff ratio 1st-21:1, 2nd-12:1, 3rd-8:1, top direct drive 5.29:1. for the series E. it also quotes for the MM 1st-17.9:1, 2nd -10.45:1, 3rd-7:1 and top-4.55:1. The drain plug on the cast iron gear box is 7/8 BSP. as is the filler plug. I checked the filler plug on the gear box in the car and it is exactly the same. the studs in the grey box in the vice are 5/16 unf and the setscrews in the front are1/4 unf.as is the out put shaft unf. This box was in the car when I bought it but may not be the original box as this car according to the first log book is the 3rd engine it has had. There is no record of gear box changes as regulations in the early days didn't require it to be logged. The blue engine and gear box running in the test rig are in the car now whilst I rebuild them over the winter. I will try and get hold of the series E box I sold to my friend as I dont think he has fitted it yet. I suppose I could change the output end and it should go into the MM. I will get some photos of the axles on thursday.

Cheers Iain.[frame][/frame][frame][/frame][frame][/frame][frame][/frame][frame][/frame]

[BLOWNMM]

Hi Iain
Firstly the diff studs are indeed UNF – my stuff up. I have also edited my post of Dec 6 to correct the location of the stamped number to the left side. I am at present cannabilising a box to modify a set of synchro dog teeth to enable fast WOT gear changes. This box also has 8 mm. X 1.0 mm studs and 6 mm. ISO metric screws at the front. I am mystified as to why your boxes have UNF threads. The 7/8 BSP filler and drain plugs you mentioned are very similar to the 30 mm. X 2.0 mm. in my boxes. There is only 7 thou difference in diameter and the BSP at 14 TPI calculates out to be a pitch of 1.8 mm. Would you put a screw pitch gauge on them to see if they are 2.0 mm. pitch or 14 TPI. In my initial post of Dec 4 at 10-48 in the link in the 5th paragraph it states that Morris engines were built with all measurements in metric. Whether this continued through to the MM we do not know. It certainly did with all of the Series E and MM boxes I have worked on. Nevertheless the different threads is puzzling to say the least. I have attached some pics of the diff, box and gears I am modifying out of interest. I am wondering if any guys following this have a Series E or MM box that they could measure the threads on and report back. I believe the MM rear housing is directly exchangeable with the Series E.
Cheers Bob

[smithskids]

Hi Bob, Axle on rh. is No19956 all unf bolts and nuts, I suspect it is an overhauled unit as it has a nyloc nut(5/8X18tpi) on the propshaft coupling or maybe someone just changed it.casting No 102118. 8/43 ratio. Axle on Lh is No 95046 all bsf nuts and bolts, this is the axle that was on the car when I bought it. Casting No 101505RR . 9/41 ratio. Propshaft coupling nut is 5/8 bsf. You were right about the drain and filling plugs on the gearboxes. with a thread gauge they are 13 tpi or 2 mm pitch and not 14, and just a shade under 30mm !! good job I didn't wop my 7/8 tap down them. as you can see in the rear axle pics the plugs are bsp tapered Cheers Iain.[frame][/frame][frame][/frame][frame][/frame][frame][/frame][frame][/frame][frame][/frame]

[BLOWNMM]

Hi Iain
Thanks for the reply. It would be interesting to know why and when the diff threads changed. Would be also of interest to hear from others re the gearbox threads.
Cheers Bob

[BLOWNMM]

Iain
As an afterthought because of the way Morris Motors stuffed around with BSF/Whitworth head sizes on various threads, when working on the diff you say has BSF fastners make sure the studs and nuts aren't UNF with BSF head sizes.
Cheers Bob