Hymn to the 1928 Model C

[Vincent.vanGinneke]

Well, at least that Matchie has loooong pushrod tubes, just like my Model C.
back on the track now.

[nevhunter]

Lots of mods to the AJS/matchless frame swing arm and fuel tank. The motor still has the AJS oil pump that weakened the timing side main bearing The 350 motor would be lucky to put out 21 HP. Motors went just as hard in the Late 20's. Nev

[Karol Burger]

Well, at least that Matchie has loooong pushrod tubes, just like my Model C.
back on the track now.

20240206_234530.jpg

the 1928 OHV model is incredibly beautiful. It is such a tall giant in a simple frame. Beautiful lines.

[Vincent.vanGinneke]

The Clutch.

My Model C came with few parts from a original clutch.
the basket and the clutch centre.
Centre part needed the stud holes redone, welded them up and retapped the holes in a different position and made up new studs from some -I think- old Honda engine through bolts.
I dunno much about material specs so I just grab something that I think will be o.k. for my needs

Then on to the clutch basket, for a change, that was in a reasonable condition.
Although it will need new rubbers for the schock absorbers
As been written in another post on this forum, yes, the rollers stick out :

But I think I see on this drawing there were really slim rollers in there, the ones I have are 350 bigend rollers.

now I have a cunning plan

a cunning plan .....jpg (68.38 KiB) Viewed 376 times

grind them down one by one

Lets see if I can pull that off .....

[Karol Burger]

I did it that way too. I sanded each one separately and then it worked fine.

[dave.owen]

Available from Draganfly

[Vincent.vanGinneke]

Thanks Dave ! that's a escape route

[Vincent.vanGinneke]

The rocker box. (reader alert, section unfit for originality bum eyes, and professional moaners in general ! )

Although I have the original rockerbox I wanted to find out if I could use later rockers.
Hmmm, it looks like they would fit.
First task was altering later spindles, the diameter did not change over the years.

I used for the test a worn one, (no usable Ariel parts are being hurt in the test process) the one in the centre only needs shortening.

To get them fitting the repro casting, (from Karol) it needs some alterning.
as the (outside) rocker arm sit under an angle, the slot in the box needs to get wider.
Also a small amount needs to be taken away around the inside arm .

view from underneath :

Using rocker arm springs as the later rockers are shorter overall.


Ah! and there is always a 'but'.....

I found that the later ex rocker has a different angle ! (did you know that ?)
I assume it's because a twin lobe cam has the position of the pushrods not in line.
(but a '28 also has a twin lobe......making a different angle at the ex rocker arm is perhaps an advanced insight at the factory ?)
With the advent of the single lobe the pushrods went back in to one line.
I can only conclude that the Ariel factory in all it's wisdom decided that the ex rocker arm could stay put.
(I always forget : is with the twin lobe the ex lifter the last one to go on the spindle ? ehhhhhh )

Anyway, this was a surprise
At the yellow arrow you see that it sits too close.
Fitting the pushrod tube + pushrod jams the plot.

pic shows another ex rocker with paddle for lifter still attached.

Question :
Would it be o.k. to heat the rocker arm and give it a knock in the right direction ??
these parts are -I think- cast with no special treatment, so heating and bending would be o.k.
yours thoughts please !

[adrie.degraaff]

I wouldn't have a problem doing that.
It's working with footrests and brake paddles so why not with this.

[Roger Gwynn]

It should be a steel stamping or forging rather than a casting, so should be OK.....