Anglian Rear Shocks

[Keith Beach]

My THS Anglian is currently fitted with Betor Rear Shocks 13 1/4 inches long between centre of bolt holes when extended. They are well overdue for replacement.

Obviously there is a fair degree of personal preference in suitable replacements but I would welcome comment and advice.

I like a soft travel ie light damping and quick reaction. I am thinking of NJB TrikShoxs. They have been recommended to me and I have found Norman Blakemore to be pretty helpful in the contact I have had with him.

I think originally the Anglian was fitted with 11.9 inch Girlings. Is that right? Norman tells me that he normally supplies 13" shocks for Anglians.

Many thanks

Keith

[Rob]

Keith,

I've got Betor on the back, about the same length as yours. You are right, the originals were 11.9" with 60/90 springs. I have 50lb springs on mine and wouldn't mind trying 40. However, they seem to work ok, I can't blame them for my poor riding unfortunately!

I have Norman's trik shocks on the front and they too are fine. I had a bit of fun fitting them because of the proximity of the fork loop to the spring but made up a couple of spacers to overcome that. The forks seemed fine in the 2 trials at the weekend and there were a few little logs to go over but the forks coped with them ok.

If you've got lots of money, you could try Rockshocks or Magicals!

[Don Morley]

Anglian Rear Shocks

The originals were 11.9" Girlings as Rob says, but the rear wheel size then was 19" with a smaller than usual WM2 section rim whereas most of our bikes now are on 18" and WM3 rear rims, meaning not only was the original tyre 1" bigger, but because the WM2 rim pinched it in further, the tyres circumference also stayed larger than it would have on a WM3 when you let air out, hence the need for at least 1" longer rear dampers if you wish to retain the Anglian's original steering geometry.

Going up much more than that though, for instance to 13.9, and you start to upset the handling as well as the need for quite massive chain slack due to the swinging arm being pushed so much further down. Certainly you will have to fit a sprung type rear chain tensioner to take care of this, and fit a much larger 64/66T rear sprocket (standard was 58 tooth) so as to raise the rear chains top run.

Failure to do this would result in the chain rubbing on, and eventually through the upper swinging arm cross member, and it will also catch or rub on the upper edge of the cross over brake pedal (Assuming you have a later Anglian).

Don Morley

[Keith Beach]

Absolutely right Don I have an 18" rear tyre. Now I understand why a 13" rear shock makes sense and I'll go for that I think. I bought the bike with a 64 tooth rear sprocket on it. I am going to change it down to less teeth. Would changing it down to a little less than 58 cause any problem ?

I had a look at the RockShoxs and Magicals Rob but they look a bit flash and un Anglian to me. Besides even if I was tempted by them, and I am not, I think people would think I was someone who could sort of ride ok on one of those newish trials bikes without proper seats but that I was not good enough to be competitive and so had bought a classic bike all tricked up and was then entering classic trials because I thought I had a better chance of winning. Truth is Ive never owned a newish trials bike, am rubbish on both types of bike and dont care.

Thank you Rob and Don. What a great website/forum this is. Just the kind of info I was looking for. I'll be able to call myself a "Greeves Anorak" in no time at all ! On a serious note I did wonder if any GRA member had surveyed Anglian owners preferences on a range of things Anglian and documented it anywhere, for example: timing BTDC, whether they had swapped to electronic ignition, jetting, changed carb, petrol/oil ratio, primary drive oil, fork oil sae, shocks, gearing etc etc.

Anyway my thanks again to you both.

[Dick F]

Anglian Shocks

Hi Keith,
If as you say , you will use it on road more than off, you must get it geared up a lot more. Rob has the same gearing as me and at 40mph it starts to ring its nuts off, also the riders as well.
I have had Betor shocks for several years now, and NJB also, I have interchanged these from front to back and the best I prefer is NJB front, and Betor rear, it is trial and error and to get it the best would take forever and a day. for road use only a chain tensioner is not that important Dicky

[Keith Beach]

Hi Dick

Thank you for that. Sorry I had to shoot off the other evening.

best wishes

Keith

[Kelvin]

Shock Absorbers

Hi,
Falcon shocks are very good and what the other people have said is correct you shold give Robin a call real nice guy,I am glad you are replacing them I saw your bike at Peter Savages

Regards
Kelvin

[Phil Hyde]

Shock length - ?

I have tried a few variations on the Triumph-Greeves over the years. I know this thread is about Anglians but the TFS with banana forks is very comparable. Even Don (Morley) agreed with that set-up in one of his books.

Longer shocks can start to alter steering geometry, so you need to think about what it is you are actually trying to achieve. I too spoke with Norman Blakemore and with his guidance went for longer shocks front and rear. I have the luxury of banana forks. It really does work and makes the bike steer better, especially on tight turns. The other advantage being more wheel contact.

Hope this helps

[Keith Beach]

Thanks Kelvin and Phil. Your comments are really helpful. I'll have a look at the Falcons although I think Im heading for another chat with Norman and some NJB shocks.

best wishes

[Don Morley]

Anglian Rear Shocks

I hate to disagree with Rob and Dick, but if you read the latest Forum home page you might just think it significant both of their own JACKED UP bikes suffered chain off troubles in the recent Downland Trophy Trial.

Anyway, as Dick says rear damper length it might not be quite as important if you are only using the bike on the road, but in my view it still is because by lengthening the dampers you will quite massively increase chain snatch even on a road bike, and this in turn increases chain and sprocket wear in addition to overloading the gearbox main bearing.

The chain will of course still snatch to some degree even with Greeves's standard 15T to 58T sprockets and 11.9" damper set up, but only slightly by comparison this likewise would be much limited by fitting a modern style sprung chain tensioner. Indeed chain snatch need not be a major problem even with 13.9" dampers, but in my view a tensioner then is a ABSOLUTE MUST.

Likewise please do not forget to set the swinging arm rubber bushes up properly. I.E. It is quite vital to slacken off the swinging arm nuts or bolts (Holding the standard type footrests on) and rear damper bolts etc. Then hold your weight down hard over the very back of the machine so as to force the dampers down idally to the half travel point.(I even make a jig for this)

Next whilst still holding the back end down re-tighten the swinging arm nuts nuts and then nip up the damper bolts etc. The so important reason for this is so make sure the Metalastic bushes are in mid tension and at mid travel position when the machine is in the settled poition. I.E. when it is being ridden normally on the road rather than the rough with a rider of YOUR weight.

This also has a surprisinly noticable knock on effect on the chosen damper spring rates and settings as well (Try it and I am sure you will find a big difference if your machine was not set up properly before).And yes if you are using your Anglian mainly as a road bike then I do think you would not only be best to stick to 11.9" dampers, but also with modern Hagon Greeves Anglian replica dampers as they not only damp well, but also look original.

Finally back to Rob and Dick. Both they say they are using the same gearing but the machines are not nice to ride at anything over 40mph, but they do not say what sprockets combinations they are using? This worries me as my Anglian used to fly round the 100 mile British Bike Chamionship trials at a much faster rate than that. Making me suspect they are gearing for the more nadgery pocket handkerchief type trials rather than such as the Trials they are now entering?

Don

[Rob]

Don,

I know this thread is about spring units but just a bit about that Perce Simon section! There was something very strange lurking in that swamp because it also felled Mr Miller as well as the sidecars! I think the liquid mud was full of fine gravel especially as it was almost in the gravel pit!

With my little short legs (and even shorter pocket!), I would have liked 11.9" rear units but it seems most makes don't go down that small. Anyway, I have 50 lb Betors on the rear and NJB's on the front that Norman said would be OK and they are. The other weekend, there were a few small logs and the forks dealt with them very well.

Straying off thread again, my gearing was 20T engine, 15T gearbox and 60T rear wheel (30.96 first gear). I found this to be too tall at last year's Perce Simon. I have since changed the gearbox for a 14T (33.17 first gear) on the advice of another competitor and I found that perfect this year. For pocket-hankerchief sections, some people are using really low 1st's, I know there are 17T engine sprockets and 13T gearbox out there!

The standard 15/58 of the Anglian would have been too high for the Perce Simon but may have got away with it at the Downland (but only just). I'll find out a bit more at the Jack Thompson this weekend!

[Colin Sparrow]

Finally back to Rob and Dick. Both they say they are using the same gearing but the machines are not nice to ride at anything over 40mph,

Probably knackered engines....

[Don Morley]

Maybe too much body weight? Or very slow speedos?

Don Morley

[Keith Beach]

Thanks Don for the further comments and advice which I read with great interest and printed out for further reference.

I had a chat with Hagon and their shocks, as you probably know, are 300mm ie a tad over 11.8 inches. Im running an 18" rear wheel and I understand that is an inch less than the original Anglians which had 19" at the back with 11.9" Girlings. So if I fitted the Hagon's wouldn't I be altering the intended steering geometry and need to add an inch on to the shock length to retain it ie fit a shock that is about 13" like Rob's ? I have seen both Rob's and Dick's bikes and from my novice eyes they don't look jacked up though I haven't ridden theirs or compared them with a bike with 11.9" shocks.

I'm running a 14 tooth front and 64 tooth rear sprocket and the bike seems quite happy to accelerate crisply and cruise briefly on an open throttle up at 40mph but I slacken off because off the highish revs.

I'll check out the swinging arm as you suggest and incidentally do think I need to get a chain tensioner - with my current shocks and a large rear sprocket the chain does run over the swinging arm and I note the previous owner had fitted a rubber pad there..

best wishes

[Don Morley]

Anglian Rear Shocks

Hi Keith,

Three points. First you are forgeting the difference in machine height terms between a 18" and 19" rear wheel is NOT 1" because it has to be split half inch above the wheel spindle and half inch below, meaning all you are losing via the difference in wheel rim size alone is just half a inch.

Secondly this in turn is almost entireley cancelled out by fitting modern tyres as they have greater tread depth, and thus also thus a greater outer diameter than the original period tyres did when your Anglian was first made, so such as a genuine 1960's 19" Dunlop would have virtually the same outer diameter as a new 18" today, hence canceling out any geometry changes in practical terms.

Finally, and for instance, neither Mr Greeves or any other Trials motorcycle manufacturer could ever possibly know how heavy the purchaser would be of any new machine, so even the damper setting and 'As supplied' spring tension had to be fairly arbitary anyway.

So then or now if you set the rear or front dampers spring tensioning cam too softly for your own weight what happens is you will only have 8" dampers in very real terms EVEN if they actually measure a over long 13.9" when unloaded! Set them mid way and maybe they will be nearer 9" etc, and in your instance meaning if you set such as VERY slightly shorter modern Hagon's at max tension they will still retain more of this actual length than would a set of 13.9's set up too softly.

Best Wishes, Don