Clevis Pins

[jja66uk]

My Nipper (G-ARFV) has just been through its permit (failed on undercarriage rings) and has had an 'advisery' to ream/drill out the control surface hinges and replace the 3/16" dia clevis pins with 5mm dia pins. Does anybody know where I might source some 5mm pins of an equivalent material to the originals? I've tried to look up the reference given in the Mk2 Owners manual (i.e. SP/4Z/B14-0 3/16") but I've drawn a blank. The brakes on my machine have been replaced at some time with bicycle brakes and have been approved by the PFA (as was). If anybody would like a copy of the bumf that had to be produced (mostly hand written calcs) to get this mod through I'll be happy to copy it and send it to them (it is very disorganised though).

Thanks

John

[Neil Spooner]

Hi John,

A 5mm straight reamer is available here:

http://uk.farnell.com/jsp/displayProduc ... 2-00001000

Do you have a material spec', if so I am sure a competant machine shop could make some, or do a search on the 'net, there are plenty of clevis pin suppliers out there. This outfit gives the material spec, but the pin would have to be drilled:

http://www.springfix.co.uk/purchase.php ... 8&method=a

Neil

[jja66uk]

Thanks Neil

I've sourced clevis pins at Boneham & Turner who seem to stock plenty of sizes and material specs. I'm regarding reaming out the holes as a short term solution, in the long term I plan to replace the hinge-bolts with oversize ones and to use replaceable bushes. However as this involves cutting fabric I'm hoping I'll be able to leave it until my Nipper is ready for recovering. I'd like to modify my engine to run inverted (only for very short periods to get me out of trouble). I believe you've extensively modified your old 1834 engine with an inverted oil and fuel system. Did you use a flop tube in the fuel tank?

Cheers

John

[Neil Spooner]

Hi John,

I am glad B&T sorted you out, were they good to deal with? It would be worth extending the reamer so you can be absolutely sure of aligning the reamer with the holes. My aileron hinges could do with new clevises.

The flop tube was already installed on my Nipper so I am unable to give you any detail on that other than it's fixed at the fwd end of the tank, if you need more detail then let me know. My oil system is now different to the std Barry Smith system, in that I have a "top tank" above the engine which is part of the inlet manifold. Let me know if you need more detail.

Neil

[Neil Spooner]

BTW, John, what are you doing re' your bungees? NeilD and myself are on the case and hope to get HD1080s approved subject to testing.

Neil

[JAB]

Neil

I am lucky in that I replaced my bungee's two years ago and all is well - so far, fingers crossed. although I am following your progress with interest.

I am also looking at replacing my brakes with ones from RST using DX disc brakes. I was shown these brakes by Chris Turner of Breighton fame, as fitted to a Fitlzer he is building. They look the part except for needing two levers, I am investigating the possibility of converting to one.

cheers

JAB

[jja66uk]

Hello Neil

I haven't ordered from B&T yet but when I do I'll let you know, you can download the catalogue from their site for sizes etc. The only problem I can forsee with them is that they might not do the correct length in imperial (I haven't measured the pins on mine yet, 50 mile trip to the airstrip so I try to bunch jobs together). I've ordered a set of rubber rings from NK&C. Alan's just taken delivery of the raw materials and he's having them machined. He says they'll be ready in about a week so I'll be expecting them sometime in January (I'll happily eat my words if they turn up next week) . I saw your post regarding the bungees and that seems the way to go in the future. I'd appreciate any info you can give me regarding inverted fuel and oil, one of my major worries is the engine stopping while inverted (no starter). How does the tank breath when upside down?

Thanks for the advice

John

[jja66uk]

Hello Neil

I had a chat with Alan of NK&C today, he's done a great job and he's posting my undercarriage rings on monday (still waiting for the first of the fuselage frames to come off the line though). I saw somewhere on the forum that you'd made a tool for changing the rings. Would you mind giving me the basic dimensions so that I can make one for myself? I've a feeling it'll be a pain of a job trying to lever the things into position.

Thanks

John

[Pat Blenkinsopp]

Greetings Jab,
Just for information ,( assuming that the brakes you are considering are small hydraulic ones)
I have found that my system using a single master cylinder mounted on the control column,
ie the brake handle (they are bicycle hydraulic disc brakes) running down to a 'Tee' piece in the
hydraulic line and splitting to each calliper. The Tee piece is secured in the region of the bungees.
This system works brilliantly and was the single best mod I did to ASXI.
I can secure some photos if you want. The discs themselves were made by me out of 1.2mm
4130 sheet steel using the original stainless ones as a pattern. They are sufficiently stiff so as
not to warp when hot as the originals were.
All the best.
Pat
G-ASXI

[JAB]

Thanks Pat

The brake system you are using appears to be very close to the one I am looking at.

I am out of area at the moment, but would be grateful for a pic or two.

johnsueb8@aol.com

many thanks

JAB

[Neil Spooner]

Hi John,

Probably the best thing to do is an "article" on the inverted oil/fuel system at some time. If you are running a carb' then flop tubes/breather mods won't help you, you MUST stay away from neg' G otherwise you risk an engine stoppage. Do your aero's over a landing site of some sort, please also make sure you are up to speed in spin recovery/unusual attitudes before you try it in the Nipper.

Neil

[jantar]

Hi John. I have fitted cycle disc hydraulic brakes to ZS-DUT and am quite pleased with the outcome. It sure was a long and hard development job and has yet to be seen by inspectors here in SA. I am interested in your offer of "bumph" as an organised set of calculations might help here. Can you E-mail same ? Eventually I will produce drawings for my mod. which suits the 6 bolt wheels, but involves longer bolts new discs and wheel spacer "doughnuts" & can make these available to the forum. Jantar

[jja66uk]

Hello Jantar

I'll scan the stuff and email it to you. Its a bit of a mess though, all hand written and not very organised.

John

[jantar]

Thanks . I presume you can get my adress from the forum. Presently breaking in the engine in ZS_DUT and getting all its systems to work. Tom H