Ariel Owners Motorcycle Club

For anyone carrying out a rebuild of their Leader or Arrow I would strongly recommend that you check that the swinging arm is not bent or twisted so that you can get it straightened before you have it painted and fit it to the bike when you might notice the rear wheel is leaning over, or source a straight replacement, but be careful if buying unseen as I've been caught out. In particular the early 'D' shaped swinging arms are more prone to twisting than the latter 'Round' type although I've found some of the round type twisted also. Have had to have four straightened to use on rebuild projects of late but that still leaves me with a pile of twisted swinging arms, all these in the photo are twisted/bent.
Jess

What's the main cause of the twisting, Jess - I can't imagine its torque ?

Just not strong enough for side forces on Britain's pot-holed roads ??

Bob.

Just not strong enough Bob. Have a look at the attached photo, cross section cut of a 'D' shaped swinging arm at the thickness of the metal. You can see why the pillion footrests droop down eventually. Jess

Jess - have you got a 'tame' swing arm straightener who knows how to do these? I've got a twisted one as well ('D' section, I didn't realise there were two types or I might have avoided it.) Maybe at some point the Club ought to consider getting a stock of straightened swing-arms, I think there might be at least a dozen out-of-line examples in the two-stroke spares that John Ellis used to have (unless he binned them!)
Do the racers fix this by just putting in extra gussets on the cross-tube, I wonder....

SG

Simon, I do have a 'tame' swinging arm straightener, unfortunately having just spoken to him about straightening one for you, he can't, he cannot take on anymore work, he simply has too much on at the moment, he sends his apologies. The attached photo is of two Round type swinging arms that have been converted for rear set operation similar to how the Ariel Factory did it in 1961 for the Arrow Production racers that they made for Dealers who entered them in the long distance races, the Thruxton 500 miler and Silverstone 1000. As regards adding extra gussets, the most common way is to add a plate top and bottom of the front cross member, sometimes boxed in, the attached picture shows the style, this is a cardboard template that gives you an idea of what its like, note though this has an 18" wheel, the standard 16" wheel wont be so close. others add gussets down the sides also as per the third photo, perhaps not really needed but they are just making sure on their racer it wont twist. You will only be able to add the gussets at the front on a road bike if you are prepared to shorten the length of the inner mudguard, for a road bike go for a Round swinging arm and you should be o.k. Jess

Jess - thanks, I'll look out for a round one, and maybe have a think about gusseting it.
Might also experiment with straightening the twisted one!

SG

Hi Jess

The racing versions look good, may copy that but thinking it’s not so efficient to have feet on the moving suspension!
Think I might also angle the footrest pivots back to 45 degrees so they could fold up in the event of a spill...
I’m intrigues as to the purpose of the piece of Swiss cheese on the left side below the axle location?

Ivor

To be honest Ivor I've never found it a problem or concern to be using the footrests on the swinging arm, only on very rough surfaces do you become aware of the swinging arm moving up and down and then its only slight, your knees tend to automatically pivot your lower legs. That said you are stuck with the height they are at, some riders prefer a higher footrest, others a lower footrest, some further forward others further back, that is something you can account for when making brackets that bolt onto the crankcase for the rear footrests. Regarding rear footrests, to pass scrutineering both race and parade bikes have to have fitted non folding footrests so that they don't fold up in the event of a spill, my Salt Arrow failed scrutineering first time around as I didnt know this with it having folding footrests got it passed when I was able to show them by tightening up the nut and bolt that it was sufficiently tight not to fold up. Regarding the alloy bracket plate at the rear of the swinging arm, again this is an A.C.U requirement when racing and parade riding to have one fitted, they are known as, a Sharks Fin and is there to stop your foot getting trapped between chain and rear sprocket in the event of a spill. This is the Sharks fin on my Cafe racer. No set design as long as they can be seen to be capable of doing the job. Jess

Surely the easiest way around the folding rear footrest issue is to remove the actual rest for the parade?

Not really Tony, I would have nothing to put my feet on, this factory made Production Racer does not have rider footrests fitted only those on the rear swinging arm. Jess