1948 Sq4 basket job - help!

[RayBlack]

I am (cautiously) thinking of buying a 1948 Sq4 basket job (plunger 4G). I am pretty sure it is reasonably complete and original and the seller has a large collection of parts to hopefully supplement any deficiencies. It will be the first Sq4 I have restored. I have a very nearly completed '39 4G being restored for me which will be coming home in the near future. I've been quite involved in that project so this new '48 project would not be totally alien to me. I am still tinkering with my '28 Black Ariel and have a few other bikes to keep busy with at present meaning the '48 Sq4 project will be something for the future. Thus, I want to be sure I get all the correct parts whilst they are available. My plan was to peruse the pile of parts and optional bits and pieces with a copy of the parts book, but unfortunately, I do not see a parts book listed on the club website. I specifically need to be sure I am getting the right speedo, gearbox, tinware, and other rare and hard to find parts. Pictures of original and/or restored bikes appear to be thin on the ground here in Canada. Any advice would be greatly appreciated.

[chris.shearwood]

Although the 1948 Sq4 would have a chronometric speedometer, the rest of the bike should be pretty well the same as your 1939 model. Some of the other exceptions: different taillight, rear stand instead of a centre stand, connecting rods with steel backed bearing liners, telescopic forks. For my 1946 Sq4 I have used the 1939 Parts List as I don't think Ariel published post war Sq4 parts lists until the 1949 model year.

[JohnnyBeckett]

hi, Ray have you tried Drags they do copies of parts books they may have the one you need

[Roger Gwynn]

There is a 1947 parts book available at Draganfly. An excellent if somewhat laborious way of doing the job but one that I use with an unfamiliar machine. Not every last nut and bolt is listed in the parts book but nearly so. Details of Lucas parts are better found in Lucas publications, I can send you a copy of the relevant parts of my Lucas listing if you like, send me an email, membership@arielownersmcc.com

[RayBlack]

Thanks Roger. Email is on the way and I will be ordering the parts book.

[RayBlack]

Thanks to Chris and Johnny for the replies.

With regards identifying the correct BA gearbox: looking at Roger's notes it appears the BA gearbox went through something of a transition in '48 resulting in a variety of prefixes to the stamping numbers. Did all these variations use the chronometric speedo (I definitely do not have access to a 100mph PA)? If I can't locate a specific '48 model gearbox would one from another year fit and function correctly? My friend with the parts states he has a few Burman boxes some without stampings - any ideas about how to ID these???

A parts list for a 1947 model provided by Roger (thanks again) shows a 100mph chronometric speedo part number 5202-47. Does anyone know how to identify the speedo from the numbers on the face?

[paul.jameson]

When thinking about changes to BA gearboxes, remember that there are two versions of the gearbox throughout from 1937 to 1952. One version is for the singles (and also, eventually, the twins) while the other is for the Square Four. The fundamental difference between the two versions is the location of the mounting lugs. Immediately postwar, Ariel still used PA speedos. They then went to chronometric but got the gearing slightly wrong and had to revise it in January 1950. So there are 3 types of speedo gearing in BA boxes post war.

Remember also that Ariel bought in their gearboxes from Burman complete with the clutch. This too can lead to different gearbox numbers, the best example being the later GB5 and GB6 gearboxes where the only difference is that the GB5 has a 2 plate clutch and the GB6 a 3 plate one.

Roger's list https://draganfly.co.uk/wp-content/uplo ... el_vin.pdf is much the best guide to gearbox numbers and do remember that for postwar gearboxes, the A 46 (or equivalent) after the gearbox type number (eg G8) means made in January 1948. A = January, B = February, etc, letter I not used.

The letters and numbers on prewar gearboxes we can usually translate and I am slowly developing a tool which gives an idea of the date of manufacture of the gearbox but progress depends on finding more bikes which have their original engines, frames and gearboxes.

[RayBlack]

Thanks Paul. I understand the Sq4s had the heavy duty BA gearbox and there was a change to the chronometric speedometer in the mid-late '40s along with the change in lubricant. I have perused Roger's list both on the Draganfly and AOMCC site. What I need to know is: given a large pile of assorted Burman gearboxes which ones could I use for my potential '48 Sq4 project? And, if there are options of differing units all with '48 numbers, which would be the best one to pick? If there are no '48 units what would be an acceptable substitute? Also, if there are no numbers on a BA gearbox why would that be, and how could such a box be identified?

[nevhunter]

You have to GET the Main case that Provides the correct offset for the Sq 4. I've had cases with no numbers. I presume they were provided as spare parts (Even Paired Crankcases for W/NGs.). Nev

[nevhunter]

I've used a SQ4 case in a standard bike by machining two faces and making spacers for the other sides. It can be done the other way around also. The correct part is always preferable of course Nev