20SA Scrambler/Trials Grumph

[David Muir]

Folks,
Here's photos of project in early stages i.e.now!

[also icluded photos of my Anglian!]

[Colin Sparrow]

Looks like a TC/TCS or a TD/TDS, yes?

What lump are you putting in it?

By the way, if you're planning to update as work progresses, we might move this post into "projects"...

[Stuart Baskill]

Looks like a TC/TCS or a TD/TDS, yes?

What lump are you putting in it?

By the way, if you're planning to update as work progresses, we might move this post into "projects"...

Its a 1958 20SA with a rear wheel from an MCS or MDS I think.The front wheel is after 1958.

[David Muir]

Paddle-type hub width vs. tin hub width

Hi,
Could someone measure these two sizes and see if they are (radically) different?........don't seem to have much room in the swinging arm for the paddle type!
Thanks,
Dave

[Brian Thompson]

'Paddle' and 'Tin' BHC Hubs.

Hi David,

As far as I know, the 'tin' hubs and the 'paddle' hubs are one and the same thing. As I understand it the 'paddle' is an aluminium 'shell moulding' that is 'shrunk' onto the standard 'tin' hub, primarily to increase strength and aid in cooling. I have seen one as a 'seperate' component (in amongst some Greeves jumble) and have copies of the factory drawings showing the details of the castings for front and rear 'paddles'.

These were fitted to both the 'plain' type and 'pie-crust' type hubs (as you have on your bike), and with regard to the later there might be some slight variation in width dimension to the 'plain' type hub, but I cannot say as I have no experience of this type. I know that the spoke flange and fitting arrangement (on the opposite side to the brake plate) is of course different on these due to to the sprocket mounting (i.e.'pie-crust'.) I wouldn't have thought they'd be much in it though, and clearance is often tight around the swingarm area with the earlier bikes, something which was addressed on later models (TD/TDS etc.)

In 'heavy' use (in the hands of BGS/Bickers et al) I believe it was found that the standard 'plain' tin hubs could be prone to distortion/ovality (through overheating and/or loss of spoke tension), so the idea for the 'paddle' was a Greeves (BGS?) modification to the 'over the counter' British Hub Company component to try and counter the problem, at the expense of added weight of course.

Interestingly, I once read that Brian Stonebridge was quoted as saying that he prefered to use the 'standard' tin hubs for wet conditions and the 'paddle' type for hot/dusty events.

Another 'dodge' was to fit suitably sized small washers over the end of the spokes, to help stop them pulling through the hub flange under heavy use/hard landings etc.

I'm sure our experts will correct me if I'm wrong on these points, but that is my understanding of it. I've attached a couple of pics of front hubs (plain and paddle types) to try and illustrate what I'm getting at.

Hope this helps a bit David.

Brian.

[Phil Hyde]

TriumphGreeves

Have you sorted out a set of engine plates for your Grumph?

I have plenty of advice, including some plate patterns. What is the frame number?

[David Muir]

Engine plates

Hi Phil,

No, no engine plates yet!
Patterns would be great.....frame number is 8236 SA!

Thanks,

Dave

[Phil Hyde]

Engine plates

I think SA means scrambler, which makes it a Hawkstone, but will check. Perhaps another member will confirm.

I will check to see if I have a pattern. Could you confirm the distance between centres from the swinging arm spindle to the bottom hole on the alloy beam?

Watch this space

[Brian Thompson]

Frame Number etc.

Here you go guys;

1958 20SA Hawkstone Scrambler

Engine; 197cc Villiers 9E

Model Number; M7

Frame Number; 8201/SA

Brian.

[David Muir]

Grumph

Hi Phil,
Sorry , not at home at moment so can't measure distance.......will do so when I go home!

Couple of other questions for you on Grumphs:-

1. is a head steady 'required' as per Triumphs?

2. is three/four pints of oil sufficient for a 500cc Triumph i.e. using a cub or C15 oil tank?

Thanks

[Phil Hyde]

Triumph-Greeves

David

You asked:-

Head Steady. Never seen one fitted yet. Thats not to say it can't or shouldn't be fitted. Provided the 350 or 500 engine is fitted well there is little scope for movement of the top end.

Oil tank. Any of the Cub tanks, C15, elc, will be fine. Minimum capacity 3 pints. Clearly, on a trials bike there is lot of stopping and starting. A road bike would need a larger capacity.

Hope this is of use

[David Muir]

Distance between Swinging Arm pivot and hole in front alloy beam

Hi Phil,
Have measured the above distance and it looks to be 'exactly' 400mm.....do you have engine plate templates for this frame(he asks hopefully!)?

Thanks,

Dave

[Phil Hyde]

Triumph Greeves engine plates

David

The most relevant drawing I have shows a dimension of 405mm (swinging arm to bottom hole) swinging arm to top hole is 450mm. This is reasonably close to your 400mm and because you have a bolt-up frame there will always be room for adjustment.



Phil

[MikeTizard]

Dave/Phil

I put a head steady on the Challenger simply because there was a bracket nearby that would take one. Like Phil says I'm not sure if it does anything but it just looks right. The bracket on the frame and the elongated stud on the head were just crying out to be joined .... so i did.

I've been running the Challenger with the C15 tank (is that right Phil?) with no problems for a good few months now. I recon it takes at least 3 to 4 pints. I'm using classic Halfords 20/50 ... it looks green like duckhams ... and is a fairly heavy oil when cold. I've had no problems at all.

Regards Mike

[David Muir]

20 SA/Triumph

Some conversions I have engineered have used the engine as a stressed member. The majority however, are passive. The shape/outline of the cases dictates that you add the plates to the engine, then the frame,............

Read with interest , the above (Triumph Greeves threads.)
Have got my plates cut out(thanks for templates , Phil), and am now offering engine/plates up to frame. Didn't realise how 'tight' it all would be but feel better seeing Phil refer to only millimetres clearance at swinging arm.
Do the plates get bolted 'hard' to engine and then the whole lot spaced as necessary or are there spacers twixt engine and plates?
Thanks