Simes' FH Rebuild

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simon.holyfield
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Simes' FH Rebuild

Postby simon.holyfield » Fri Oct 26, 2018 10:02 pm

And here we go, the start of the FH rebuild! We had a preliminary look at the bike here:

viewtopic.php?f=21&t=8545

but now I want to start a new thread with the rebuild proper. This is what I am going to do:

  • Strip the top end and timing side off the engine, to release the head, barrel and engine plates for the dry build and to release the magneto and dynamo for reconditioning.
  • Put the frame on the bench, and assemble the gear box and empty cases into it
  • Start welding the mudguards, chain guards and seat pan to trial fit tinwear and frame components
  • Dry build, with fasteners from stock and no engine internals, wiring or cables.
  • Register, photograph and develop the 'missing & broken parts' list
  • Send black items (cycle parts) out for powdercoat
  • Rebuild the wheels
  • Send the levers and handlebars out for plating
  • Send the tanks, toolbox, and mudguards out for paint
  • Start the engine and gearbox rebuild
  • Reassemble when it's all back...
  • Wiring and cables
  • Shakedown!

So after finishing some woodwork, I lifted the engine onto the bench to start work using my chinese 1000 kg chain hoist, which made short work of the lift and saved my back:
IMG_20181026_162016.jpg

I've had an engine stand for some time. I described it here:

http://ariel-square-four.blogspot.com/2 ... stand.html

and I used it's built on flexibility to manoeuvre the FH into a suitable position:
IMG_20181026_163530.jpg

Of course, the purpose of getting it onto the bench was to have a look see. I hadn't noticed this broken bolt, or the worn splines before:
IMG_20181026_163831.jpg

These are not the original crankcases for the bike, so I'm not too worried about that bolt - I have the original cases in storage - but what do you think of the splines?
cheers

Simes

'51 Square Four,
'58 Huntmaster,
'42 W/NG,
'78 CX500
http://ariel-square-four.blogspot.com

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simon.holyfield
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Re: Simes' FH Rebuild

Postby simon.holyfield » Fri Oct 26, 2018 10:43 pm

So moving into the top end, I took a look at the rocker box. I've loosened everything, but will keep the rocker box in one piece for now. First issue is a stripped stud:
IMG_20181026_170615.jpg

Removing the inspection cover studs, I find one elegant Ariel stud with BSC threads at both ends, one 1/4" for the nut and one 5/16" for the rocker box. The other one, which has no nut is bent and is 5/16" both ends, one BSW, one BSC. Obviously a replacement but a shame, because the thread in the rocker box has been recut BSW. I'll be making a special on the lathe.
IMG_20181026_170130.jpg

Next issue, a broken fin. Not sure currently what I will do about this - I think it is the one under the head steady, so is hardly seen in service. Is it worth risking the head to try and weld it?
IMG_20181026_164557.jpg

Lastly, some cornflakes gaskets for general amusement!
IMG_20181026_164551.jpg
Last edited by simon.holyfield on Sat Oct 27, 2018 10:15 am, edited 3 times in total.
cheers

Simes

'51 Square Four,
'58 Huntmaster,
'42 W/NG,
'78 CX500
http://ariel-square-four.blogspot.com

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simon.holyfield
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Re: Simes' FH Rebuild

Postby simon.holyfield » Fri Oct 26, 2018 10:48 pm

Next up, cylinder head - a general view. Looks OK, bolts were very tight but came out with some effort:
IMG_20181026_171242.jpg

Springs are all sound. Here's the underside of the rocker box:
IMG_20181026_171257.jpg

Quick shot of the underside of the head
IMG_20181026_173731.jpg

Bores and pistons. After I took this shot I gave them a quick clean up - the bores are unmarked and have no ridges; pistons have no undersize showing.
IMG_20181026_173740.jpg
Last edited by simon.holyfield on Wed Oct 31, 2018 9:14 am, edited 1 time in total.
cheers

Simes

'51 Square Four,
'58 Huntmaster,
'42 W/NG,
'78 CX500
http://ariel-square-four.blogspot.com

Simon.Gardiner
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Re: Simes' FH Rebuild

Postby Simon.Gardiner » Sat Oct 27, 2018 12:21 am

Pistons look to be dished, not flat-top? (Dished are the 6.5:1, flat-top the export/sports 7.25:1)
Strange that the bores are unworn standard size but the crank splines look to have seen a fair bit of service?
The splines aren't nice but it's difficult to find someone who can reclaim them and replacement cranks (with good splines!) are difficult to find. (Taht's been my experience - other people may well have loads of them.....).
Have you got two sets of cases and only one crank? The '58 model year introduced the 'big-bearing' crank (which at least is easy for bearing shells) but I don't think it fits the earlier crankcases without a mod to the oil return pipe so that the bigger crank webs don't clip it.
For the broken fin on the head I'd leave it as is - you'll probably feel like breaking the other one off by the time you've spent several long hours trying to get the head steadies on :D .
For the crank splines, I think in A10-land they use them until they get really really worn but I'd want a good look at what other people are running with, possibly especially Mr Carter (as he's got at least a couple of cranks!). It does cross my mind that maybe that belt-drive primary conversion is kinder on the drive-side (and I think you've already considered fitting it, Simes).
I'm very curious to see what the cam and followers look like....

Interesting days??

SG
'55 Huntmaster, '56 VH, ' 51 VH, '80 R100RT, '00 Sprint ST (but all those Ariel parts can only make one running bike...)

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Steven.Carter
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Re: Simes' FH Rebuild

Postby Steven.Carter » Sat Oct 27, 2018 8:16 am

Great stuff Simon, I'll enjoy this thread.


Screenshot_20181027-080257.jpg

A bolt here removes the worry of a nut coming loose here, just means you have to remove the stud holding the rocker cover on each time you need to take the rocker box off.


If your considering a belt drive I've a spare pulley you could borrow to try on your crank, you'll see how well it fits. Or not.

I had a head with a broken fin under the head steady as well, didn't realy show at all but I'm dont think any welding repair would do any damage. The head is a mighty beast :D

If you need pistons I can recomend IMD, I burn virtually no oil with them, I never have to top up the tank between oil changes. I've just had to replace mine which lasted around 70,000 miles. The new ones are now great although I did have a scare after 15 miles when they nipped up but that was my fault. They have now done over 1,000 miles.

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Steven.Carter
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Re: Simes' FH Rebuild

Postby Steven.Carter » Sat Oct 27, 2018 9:34 am

Solid copper rocker box gaskets are your friends.

https://eborbikes.com/index.php?route=p ... duct_id=66

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Eero.Korhonen
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Re: Simes' FH Rebuild

Postby Eero.Korhonen » Sat Oct 27, 2018 11:11 am

Great stuff, thanks!
Br, Eero
Ariel VH 1954, IZH 350 1962, H-D Sportster Hugger 1992, AOMCC Member 133

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simon.holyfield
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Re: Simes' FH Rebuild

Postby simon.holyfield » Sat Oct 27, 2018 1:34 pm

Thanks for the support and information guys. I'll write a bit more later but for now, today's news is that the bores measure around 2.82" in the centre of the stroke, for & aft. That's +60 thou.
cheers

Simes

'51 Square Four,
'58 Huntmaster,
'42 W/NG,
'78 CX500
http://ariel-square-four.blogspot.com

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simon.holyfield
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Re: Simes' FH Rebuild

Postby simon.holyfield » Sat Oct 27, 2018 1:37 pm

Another thought - I've discovered that the engine I'm stripping has an LF prefix. The original cases have a CNLF prefix which I think is 1958.

What does that tell us?
cheers

Simes

'51 Square Four,
'58 Huntmaster,
'42 W/NG,
'78 CX500
http://ariel-square-four.blogspot.com

Simon.Gardiner
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Re: Simes' FH Rebuild

Postby Simon.Gardiner » Sat Oct 27, 2018 2:28 pm

Tells us you need to check the year codes as they're clearly not 1958!
And have a good look at your parts inventory to see if you've got anything else that could be from the '58 engine, as well as the crankcases, 'cos your complete one is probably a small-bearing crank unit (although it might have been altered to take the later crank).
Get it apart and put some more photos up!
Once the barrels are off, I think if the crank webs are straight-edged it's big bearing, if slightly concave small bearing. For sure the flywheel on the big-bearing has 3 retaining bolts around the outside, you can see the heads. Small bearing crank has cross-bolts on the internal side of the flywheel, nothing showing on the outer circumference. (Don't ever try to undo them....)

SG
'55 Huntmaster, '56 VH, ' 51 VH, '80 R100RT, '00 Sprint ST (but all those Ariel parts can only make one running bike...)


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