Hi all..

I'm after some help. I've just purchased a set of 'used' (but supposedly only 6 - 7 times) Sierra Scale Retracts for a 1/5 scale MkV Tempest. Tried to test them today and found them fairly 'stiff' and reluctant to retract or extend .. We gave them a light oil with transmission fluid with not much of a positive effect.

I'm new to 'BIG' models and the friend who is assisting me in my project and who has experience in 'large scale' models suggested taking the Air cylinder apart. His thinking is that perhaps the rubber 'o' rings within the cylinder could be perished and need replacing.. I've dismantled the unit and removed the cylinder but am unable to see how it can be taken apart to renew/maintain whatever there may be inside. I have a 'watchmakers' eyeglass and even with it am unable to see a screw thread at one end where perhaps the cylinder screws into itself. Is the end cap a 'press' fit with some type of glue? Do I need to apply heat (I did a little but still no good and didn't want to over do that)..

Any advice will be most welcome!

Thanks,

Bruce Hoffmann

Any light oil on the outside is fine,
Where did you put Tranny fluid,, Not in the air lines I hope??

Well I was taking the lead from this friend - who has many large scale models with retracts - and yes, some of the tranny oil went into the air lines...

Depending on the o-rings used petroleum based oils can attack silicon based o-rings,, I'd email Sierra and see what they recommend before you put any type of oil in them

Thanks... was actually in the process of purchasing some tail wheel retracts from them - emailed 'Darrell' to tell him the money was on its way through Paypal and also told him briefly the problem with the main u/c. He suggested giving me a ring to explain 'what' can be done - which is really good of him. I'll be ringing him as I can do that for no cost to the USA at the moment..

Bruce

An update to this post...

As I mentioned... I had 'help' with this from a friend and we put a little transmission fluid in the cylinders to lubricate them. It seems it worked, they are operating much better now. Have also spoken again to 'Darrell' at Sierra and he's suggested squirting some of his special grease into the cylinder (he's supplying a syringe and grease with tail wheel retract I've purchased form him) - so I'm very thankful to him for his help. He says that 'most' of the time this is the problem - the cylinders/seals dry out and just need to be re-lubricated. Failing that the cylinders will need to be removed and returned to him for replacement - apparently they are manufactured as a 'press' fit (and probably a special glue) and cannot be taken apart - at least not by a backyard mechanic!

Plenly of time to get them right before they need to go in the model..

Bob Violet sells a retract, o-ring lubricant.

Ok - thanks I'll keep that in mind for next time... the grease that Darrell from Sierra is sending me would be 'specific' for his retracts - so hopefully there will be enough to last for a few 'lubes.'

Some pics of the tempest would be nice too bruce,good luck

There are some photos somewhere else on this site but here are just a couple to 'whet' your whistle.. I've now sheeted the stab, elevators, fin and rudder and about to start on the wing..I'm hoping the tail wheel assembly will arrive in the next few days..
I'll take some more photos shortly and get them on board..

Bruce

They look good,my interest comes from being a peirre closterman fan read his book the big show as a child building models and it left an impression would like to put my saito 220 in an arf but might glue a kit together if thats what it takes,i don't have that much time,good luck with yours

I've read the 'Big Show' many times - should probably get it out and read it again...more inspiration can't hurt.. I've been away a few days and when I returned today I found my new sierra tail wheel retracts sitting in the letter box.. (glad no-one decided to snatch it out of there while I wasn't around!) - a nice piece of engineering... now back to the model... Last week before going away i cut out all the ribs to accommodate the retracts etc and laminated them where needed... ready to start to lay the wing out now..
Bruce