Gstan

How many four stroke owners use plastic spinners? I have read you should use metal only.

RCKen

My Feedback: (9)

Many will say that, but I've used plastic spinners on 4-stroke engines as large as 120 size with no problems at all with them.

Ken

horace315

My Feedback: (15)

i have used plastic spinners for a lot of years now on both 2 and 4 cycle engines,i would suggest you use the ones with the nut inserts in them over the ones with just screws.

agexpert

My Feedback: (1)

A spinner is optional......

Use whatever you like.

bigtim

My Feedback: (13)

I happen to like using aluminum spinners on my 4st engines for many reasons,I would think as long as your using a quality item it doesn't matter.
there is alot of junky plastic spinners out there, if you have had a 4st pop back at you you would know why people recomend the metal ones.

cruzomatic

My Feedback: (17)

I've used both plastic and metal spinners with my 4 strokes, like the above, no problems from either of them as well.

Deadeye

I've had a plastic spinner literally explode on a Saito 100. I'll never use plastic again. Ever.

scratchonly

Plastic is fine; don't let your prop touch the spinner prop opening, especially wood props.

Big feet

Plastic spinners don't like starters very much, and if overtightened they distort slightly throwing out the ballance.
Metal ones look better in my opinion, especially the chrome ones.

opjose

No problem with plastic... if you have the right starter cone insert, they work just fine with starters...

Overtightening plastic can be problematic, but then again, the same thing happens with aluminum...

I tightened down a 3 1/2" aluminum spinner four weeks ago, that kept loosening on me, and ended up breaking the aluminum backing plate on this expensive spinner.

I switched over to plastic on this plane and have not had problems since.

da Rock

Both me and a buddy of mine have lots of years experience with 2stokes, and we've both recently gotten 4cycles and used them.

Both of us had little trouble operating the suckers. And both of the engines ruined a number of plastic spinners. Was it our inexperience with 4strokes or the 4strokes themselves that ruined the spinners? Who cares. It happened with the 4strokes and we've yet to mess up spinners on 2strokers.

Here's the deal.
4strokes are apt to backfire. Very prone to do so from what I've seen at the club field. Matter of fact, a number of our members start their 4strokes by flipping them backwards to get them to "forward fire" into starting. And when an engine backfires it often loosens the prop nut. And of course, it happens so often with 4strokes, that almost all of them come equipped with TWO prop nuts to deal with the harsh backfiring.

And what happens to a plastic spinner when the prop backfires? Depends on some minor things, but some times the plastic cone takes a hard shot. One I've got simply sheared the locating pins. Another took damage at the prop openings where the cone mates with the backplate. They don't fit into each other anymore. Another one ruined the gripping surface of the backplate. It was plastic and was nowhere strong enough to handle the 4cycle load. It was also old and had been used on 2cycles for years and years.

Some plastic backplates distort when you tighten the propnut really tight. I'd suggest you avoid them for 4cycle use 100% of the time. Most of my plastic spinners have plastic backplates with almost no gripping serrations (on the drive washer side) worthy of the name. I wouldn't use any of them on a 4cycle. The plastic spinners with only plastic pins that locate the cone to the backplate don't go on my 4cycle any more. Matter of fact, right now, I simply don't have any plastic spinners that I'd put on the sucker. And if I ever put a spinner on another 4cycle, it'll be metal.

opjose

Heh... my aluminum backplated "distorted" when I tightened it to overcome the constant loosening that happened with it.

It bent then cracked.

Luckily I caught it before attempting to start the plane.... as I decided to take the cowl off to check something else...

Had I been in the line of fire for those metal fragements, well.... on this the plastic pieces would have caused less damage.

You can have problems with both materials as I found out the hard way.

Aluminum spinners are in no way immune to the same problems.

Deadeye

I disagree. The fastening system is different. If you set up your mating screw in surface (prop adapter) properly, it is nearly fool proof. If you bent the backplate, then you had some other problem. Nothing beats a prop adapter (properly set up), and an aluminum backplate and spinner. It would take God himself too tell me otherwise. I don't mean to be contrary, but that's how strongly I feel.

Big feet

I'm with you on this one Deadeye.

opjose

Well you can disagree... ( dunno what you are disagreeing about though... this was not speculation on my part, rather a recounting of something that has actually occurred. )

But the problem still happens on a "proper" setup, with the correct adapters.

The spinner is held by the spinner cap screw onto the adapter nut.

In turn this pushes the spinner cone against the backplate.

My spinner kept coming off during starts.

So I kept tightening it down, which eventually broke the backplate.

This is easy to do, and since the aluminum doesn't have as much give, it cracks quite easily which is extremely dangerous.

It's not that I dislike aluminum spinners, but they are simply not the end all, in terms of safety, as I've experienced first hand.

Deadeye

I wonder if your spinner was factory defective? Almost sounds like one of the pieces was the wrong size.

opjose

Why would this indicate a defect of some sort?

It's part of the stock design of most spinners.

The cap screw pulls the spinner down against the back plate.

If you tighten the spinner down too much ( which I did because of it loosening all the time ) then the outer part of the back plate is pushed backward while the central part is held fast by the prop screw.

That bends the back plate "back" to the point that you'll get stress fractures radiating out from the center.

Deadeye

I think I know what the problem is. On my prop adapters, they bottom out on the spinner when the screw is tight. I can see how a gap between the adapter and spinner could cause a deformity. You need longer prop adapters, then grind them until they mate with the spinner when tight. This effectively puts the strain on the prop shaft, where it belongs. I use the method of trial and error until I get them right.

Big feet

Try some thread lock, should help.

da Rock

Try flying 2cycles instead.

You don't have to tighten the spinner down so tightly it breaks the backplate.

You don't have to tighten the spinner down overly tight at all. Matter of fact, tightening the spinner cone has little or no effect on how tightly the backplate and prop are held to the thrust washer. So even if you are scared of your 4cycles backfiring everything loose, don't panic and overtighten the spinner cone hold-down screws.

opjose

Maybe...

I see everyone advising against thread lock on the prop shafts etc least they be impossible to remove...

As a result I've never tried it there... since I heeded the advice.

opjose

Eh, I'm cognizant that the spinner cone has no effect on the prop washer.

I've had the spinner itself come flying off and hit me in the head, which caused me to tighten it down firmly to prevent a repeat... and ultimately resulted in it cracking.

Maybe a little loc-tite would have been a better solution.

Big feet

There are a few different strengths of loc-tite. Don't use the, errrr red one, I think. It really is lock and forget stuff. The blue one is used to prevent a nut/bolt becomming loose due to vibration, but you can easily remove it when you need to. Check the different strengths out, I really can't remember which is which off the top of my head.

bruce88123

http://www.loctite.com/int_henkel/lo...id=19&layout=3

Thread-locker 222 would probably be a good choice. It's categorized as a "low strength" thread-locker.

Bill Lowen

boy, I saw a spinner and prop come off a 60 size mustang a couple of weekends back. Hit one of the guys in the shoulder. I suppose he was lucky, it was ugly though. turns out the ding dong only tightened the prop with a pair of pliers. He was a new guy and what he was doing with a Mustang (not a PTS mind you) in the first place was beyond me. I stay 100 feet away from him when his engines are turning now.